february 2017 ecg bulletin - the royal society of chemistry 2017 bulletin_tcm18-249106.pdf ·...

February 2017

ECG Bulletin

Environmental outreach. ECG com-mittee members have been involved in exciting meetings and events aimed at engaging the general public, including the week-long “Into the blue” event in Manchester (pp. 8-9) and an interactive event in Oxford exploring possible fu-tures under climate change (pp. 10-11). Environmental Briefs. We continue our series of short primers on important methods in environmental science with articles on how to assess the indoor

human health risks from volatile organ-ic compounds (pp. 21-22) and on the properties, risks, and remediation of non-aqueous phase liquids (pp. 23-24). Also in this issue. We revisit the dan-gers from neonicotinoids for bees (pp. 16-17) and the environmental impacts of rare earth elements (pp. 12-15), an-nounce three exciting upcoming meet-ings (pp. 18-20), and discuss the impli-cations of changes to the A-level sylla-bus (pp. 5-6).

Royal Society of Chemistry—Environmental Chemistry Group—Bulletin—February 2017 2

ECG Bulletin ISSN1758‐6224 Print 2040‐1469 Online Published by the Royal Society of Chemistry’s RSC Environmental Chemistry Group ECG , BurlingtonHouse,Piccadilly,LondonW1J0BA,UKExecutiveEditorJuliaFahrenkamp‐Uppenbrinkecgbulletin@hotmail.co.ukProductionEditorsRowenaFletcher‐Wood,ScienceOxfordrowena. letcher‐[email protected],[email protected],UniversityofBirminghamZoëFleming,UniversityofLeicesterIanForber,Scienti icAnalysisLaboratoriesBrianGraham,NationalHouseBuildingCouncil,MiltonKeynesMartinKing,RoyalHolloway,UniversityofLondonSteveLeharne,GreenwichUniversityRupertPurchase,HaywardsHeathRogerReeve,UniversityofSunderlandJamieHarrower,INEOS

Environmental Chemistry Group www.rsc.org/ecg,Twitter:@RSC_ECG,Facebook:RSCEnvironmentalChemistryGroupChair:ZoëFleming,[email protected] Vice‐Chair:MartinKing,RoyalHolloway,UniversityofLondon [email protected] HonorarySecretary:TomSizmur,[email protected] HonoraryTreasurer:IanForber,Scienti icAnalysisLaboratories [email protected] ForECGmembershipdetails,visitwww.rsc.org/MembershipECG.ThisandpreviousissuesoftheECGBulletinareavailablewithoutchargeatwww.rsc.org/ecg.Bulletin©RSC–ECG2017RegisteredCharityNumber207890

Contents

Chair’sreportfor2016:NewsfromtheECG,byZoëFleming 3

TheECGInterview:MartinKing 4

Article:Inthebin Appliedandenvironmentalsciencesatschool,byRowenaFletcher‐Wood 5

Meetingreport:Environmentalchemistryofwater,sedimentandsoil,bySteveLeharneandTomSizmur 7

Outreach:EnvironmentalchemistryteamattheNERC’s“Intotheblue”publicevent,byZoëFleming 8

Meetingreport:Mastersofdisaster Clicktochangetheworld,byRowenaFletcher‐Wood 10

Article:Rareearthelements:Chemistry,fateandenvironmentalimpact,byTomSizmur 12

Article:Neonicotinoidsupdated,byRowenaFletcher‐Wood 16

Forthcomingmeeting:Insidetheengine Fromchemistrytohumanhealth 18

Forthcomingmeeting:What’snewintheanalysisofcomplexenvironmentalmatrices? 19

Forthcomingmeeting:Emergingcontaminantsinwatersandsoils publichealthimplications 20

ECGEnvironmentalBriefNo14:Volatileorganiccarbonsandvapourintrusion,byJamesLymer 21

ECGEnvironmentalBriefNo15:Non‐aqueousphaseliquids:properties,riskreductionandremediation,

bySteveLeharne 23

TheECGBulletinisprintedonpapermadefromwoodpulpsourcedfromsustainableforests,andissuitableforarchivalstorage.ThisissueoftheECGBulletinwasprintedbyPrizmaticPrintSolutions,www.prizmatic.co.uk;01444239000.Allarticlesrepresenttheinformedviewoftheauthor s atthetimeofwriting,notthatoftheECGortheRSC.Theywerenotpeerreviewedandnoguaranteeregardingtheaccuracyorotherwisecanbegivenbytheauthor s ,theECGortheRSC.

Coverimage:Astudentanalysesabugonaworktable.AsRowenaFletcher‐Woodex‐plainsonpp.5‐6,upcomingchangestotheUK’sGCSEandA‐levelcoursesinenviron‐mentalandappliedscienceshavewideimplicationsforindividualstudentsandsociety.Credit:ComaniciuDan/Shutterstock

http://www.rsc.org/Membership




http://www.prizmatic.co.uk


During 2016, your committee arranged a number ofsuccessfulmeetings,eventsandactivitiesacrossarangeof topics and formats, in some cases jointlywith otherinterestgroups,andorganisations.In early March, Professor Bill Bloss University ofBirmingham organised an event on Atmosphericozonolysis chemistry.This twohalf‐daymeetingheld inBirminghamwasattendedby ifteenresearchers.This was followed by the 2016 Distinguished GuestLecture and Symposium on 22ndMarch, on the topic ofGeoengineering the climate. Professor Joanna HaighImperialCollege introducedthesymposiumandspokeon the fundamental scienti ic ideas behindgeoengineering the climate. Professor MichaelStephensonfromtheBritishGeologicalSurveyreviewedcarbon capture and storage, followed by Dr DavidSantillo of Greenpeace Research Laboratories, whotalked about policy aspects of the geoengineeringchallenge. The 2016 ECG Distinguished Guest Lecturewas delivered by Professor Alan Robock RutgersUniversity, USA , who spoke on the symposium title.Detailed reports from themeetingmaybe found in theJuly 2016 edition of the ECG Bulletin. Ninety‐sixdelegates with diverse scienti ic and environmentalinterestsattendedthisevent.TheECGhasbeenveryactive inengagingwithyoungerscientistsandearlycareerenvironmentalchemistsoverthe last year. Rowena Fletcher‐Wood attended the RSCEarlyCareersSymposiuminGlasgowinJulytoshowcaseoutreach volunteering opportunities with the ECG. Wealsobroughttogetherninevolunteerstoworkona ive‐day NERC Public Outreach event in Manchester, with ahands‐onenvironmentalchemistrystall.Theveryyoungvisitors to our stall were most fascinated by diggingaround in our soil trays, seeing dry ice in action, andtestingpH.Ourearlycareervolunteersareinterestedintakingpartinfutureevents,andourabilitytoadvertiseforvolunteershasbeenaidedbyoursocialmediaposts.DrTomSizmur University ofReading resurrected theearlycareersymposiumformat forasuccessfulmeetingontheenvironmentalchemistryofwater, sedimentandsoil, which was held at Burlington House on 14thNovember. A similar symposium is being planned forautumn2017.

DrRowenaFletcher‐Wood ScienceOxford organisedapublic science talk with audience participation entitled

“Mastersofdisaster”.Thisevent,arrangedinconjunctionwith Science Oxford, was linked to the University ofOxfordEnvironmentalChangeInstituteseriesofevents.Thenovelformatallowedleadingscientiststopitchtheirviewsoncertaintopicsinafutureworld,andinteractivevotingenabledtheaudiencetovoteonthem.Alongside our programme of events, ECG Committeemembers Julia Fahrenkamp‐Uppenbrink, RowenaFletcher‐Wood,TomSizmur,RupertPurchaseandRogerReeve continue to produce the biannual ECG Bulletin.Professor Martin King Royal Holloway is active indeveloping the ECG Environmental Briefs, a series ofshort reports providing succinct information on allaspects of environmental chemistry. Fifteen ECGEnvironmental Briefs have been produced to date,including two in this issue, and all are available on theRSCECGwebsite.WewelcomesuggestionsandpotentialauthorsforfutureEnvironmentalBriefs.Todate,theECGhasarrangedthreemeetingswhichwilltake place in 2017 at Burlington House, Piccadilly: the2017 ECG Distinguished Guest Lecture and Symposium“Insidetheengine:fromchemistrytohumanhealth”on1

March 2017; a meeting entitled “What's new in theanalysisofcomplexenvironmentalmatrices?”,organisedjointlybytheECG,SeparationSciencegroup,andWaterScienceForum,tobeheldon3March;andameetingon“Emergingcontaminantsinwatersandsoils:publichealthconcerns”,which isbeingorganised inconjunctionwiththeRSC’sToxicologyGroupandWaterScienceForum,on5April.ECG membership has grown to just under 1900members. We are aiming to recruit more committeemembers in 2017.Anyonewishing to helpwith editingthe ECG Bulletin is particularly welcome as we arelookingforaneweditorthisyear.Wewouldalsoliketoputmoreeffortintooursocialmediaoutlets,anewECGwebsite,anddigitisingandcataloguingsomeoftheECGNewsletterandECGBulletinarchive 1995–2017 .The committee is always keen to hear from members,including feedback on events, suggestions for futureactivities,andotherideas,andwelookforwardtoseeingyou in 2017. I would like to thank the committee andthosewho have participated in the diverse activities ofECGfortheirenthusiasmandforvolunteeringtheirtime.ZoëFlemingNCAS,UniversityofLeicester

Chair’s report for 2016

News from the ECG


ECG committee member Martin King is Professor of Atmospheric and Cryo-spheric Chemistry in the Earth Sciences Department, Royal Holloway, University of London. What inspired you to become a scientist? DuringmyA‐levelsstudies,Iattendedatalkatthe Cavendish Physics Laboratory inCambridgebyJoeFarnhamaboutozoneholechemistry.Iwastheyoungesttherebyatleasttenyearsandwhatfeltlike thirty years.The talkwas abit dry for a seventeenyearold.But three truths suddenly cameclear tome: afew simple chemical reactions could have an enormouseffecton theplanet, sciencecouldbemy ticket to someinterestingplaces in theworld– includingAntarctica–andchemistrywasnotallaboutmakingnewcompounds,butcouldbeusedtoexplainthenaturalworld.

How did you come to specialise in atmospheric and cryospheric chemistry? I wanted to go to Antarctica. My 4thyear degree supervisor Professor Richard Waynestudiedatmosphericchemistryandozone.Iwonderedifthis wasmy ticket, and it was: by applyingmy love ofphysical chemistry to the real world. I enjoyedmy 4thyear research so much that I stayed on to complete aDPhil in Atmospheric/Physical Chemistry, and gave upmyotherdesiretobeafastjetpilot. Icarriedoutpost‐doctoral work in Fairbanks, Alaska, where I wasintroducedtothechemistryofsnowandice.IlatertookupanappointmentinLondon,andsubsequentlyworkedinAntarcticawithItalianscientistsinTerraNovaBay.

Could you describe your current job? Icould say that I am a Professor of Atmospheric andCryosphericChemistryintheEarthSciencesDepartment,RoyalHolloway,UniversityofLondon,butthatdoesnothelpdescribewhatIdo.Abetterquestionmightbe:whatdidyoudolastweek?AndIwouldsaythatonMonday,Iixed the leak on a two‐tonne sea ice tank used formeasuringtheeffectofvolcanicashonplanetaryalbedo.On Tuesday, I was an examiner for a PhD viva thestudentpassedwith lyingcolours .OnWednesday,Imet

withthreePhDsstudentstoexplorethespectroscopy of ice‐bound nitrate,derived the error equation for anopticaltweezersexperiment,andfounda bug in a radiative‐transferprogramme. I also taught crystalstructures of simple silica minerals toirst year students and attended afaculty teachingmeeting.OnThursday,I completed risk assessments forreacting ozone with organic chemicalsfrom tree leaves tomake atmosphericaerosol,workedonagrantapplication,andattendedaplagiarismmeeting.OnFriday, I taught statistics to third year

students and then drove to the Rutherford‐Appletonneutron facility to spend three days and nights of theweekendbouncingneutronsoffanoily ilmonemoleculethick found at the air‐water interface between cloudwaterandtheatmosphere.

What is your advice for anyone considering a career in this area? Theadvice Igiveregularly tostudents is tonotspecialise intheenvironmentalaspects tooquickly. Inmyopinion, itismuchbettertoundertakeaphysics,chemistry,biologyor engineering degree and then specialise inenvironmental aspects later. Whilst this is the route Ihave taken, and soof course I think it is thebestone, IindthatnearlyeverydayIamusingskillsfrommycoresubjectappliedsuccessfullytoenvironmentalproblems.

What are some of the challenges facing the environmental science community? There is a lack of diversity in topicsstudied,andtoomuchpressureforgroupsandteamstoconformwithcommonideas.Inmyopinion,thisleadstoalackofdiversityof ideasandtoomucheffortspentonone topic, when there are so many other interestingproblemsthatneedstudying.

What is the most rewarding aspect of your career so far? WorkingwithPhDstudents.

If you weren’t a scientist what would you do? IstillthinkIwouldhavemadeagreatfastjetpilot.

The ECG Interview: Martin King


In yet another recent Ofqual overhaul of GCSE and A level examinations, changes have been made to the way in which school science labs are run and assessed, and subjects including environmental science and applied science A levels are under threat of being scrapped from 2017. Interdisciplinary collaboration is a rising trend inscienti ic research, from bioinformatics to enzyme‐directed chemical synthesis to geoengineering orplanetary astronomy – and for good reason: it iseffective. By con ining ourselves to narrow ields anddeclining to engage in research that transgresses theboundariesofourdisciplines,wemissoutoneverythingthatcannotbeunderstoodintermsofsingledisciplines,which is most things. Researchers are more and moreawareof this–andyetat the same time, in schoolsweareheadingbacktotraditionalsubjects.The loss of so‐called “soft” subjects such asenvironmental science has provoked criticism https://www.theguardian.com/education/2015/mar/03/ofqual‐provokes‐government‐scrap‐science‐practicals ,suggesting that less academic students will beunderserved,unabletoobtaintherequiredgradesinthetraditional science subjects physics, chemistry andbiology that will allow them access to scienti ic orrelated ieldssuchasnursingorconservation.However,Ofqual claims that their decision to eliminate themhasnothingtodowiththesesubjectsbeing“soft”,butarisesfromdif icultieswithstandardisingexams.AsonlyafewthousandstudentssittheseappliedAlevels,thedemandisnotconsideredsuf icienttowarrantkeepingthem.

Environmental Science This subject covers such topics as energy resources,sustainabilityand theenvironmental impactsonhealth.It overlaps overtly with biological, geological,geographical,atmospheric,physical,andchemicaltopics,whilst entwining the scienti ic information into itspolitical, sociological and economic context. And the

importance of this shouldbe heavily underlined, as thecontextual placement of science is often overlooked bythe traditional subjects, where the story of progress isone of uncovering something absolute thatwas alwaystherewaiting.Instead, I believe the decision‐making complicationsintegral to industries such as nuclear energy should beintroduced in parallel, if nothing else so that thescientistscansympathisewithpublicconcerns asmanydon’t and the policymakers responding to them arescienti ically literate which feware .Also important inthe courseare the researchand investigativeskills thatallow students to develop an understanding of thedemands in data and measurement rigour and how toappropriatelyweighandassess scienti ic evidence.Andnaturally, the topic of environmental science demandsbeinguptodatewithrecentadvances,meaningthatthecourse’s factual content ismore frequently revised andthequalitystandardishigh.

Applied Science This subject,which I am currently teaching, focuses onindependent research conducted by the students, thelegalandpracticaldeliveryofhealthandsafetyatwork,

Article

In the bin – Applied and environmental sciences at school Rowena Fletcher-Wood (Science Oxford, [email protected])

Studyingscience.UpcomingchangestotheUK’sGCSEandA‐levelcoursesinscienti icsubjectshavewideimplicationsforindividualstudentsandsociety.Credit:ComaniciuDan/Shutterstock

https://www.theguardian.com/education/2015/mar/03/ofqual-provokes-government-scrap-science-practicals










case studies into medical, environmental, educational,industrial and service science, andhands‐on laboratorywork.Although thecourse is sparinglyexplained in thespeci ication, with no example case studies and hugelexibility, it is designed to allow the deliverer to caterfortheinterestsofthestudentswhoaretakingit,bothasagroupandindividually,workingtoastandardisedleveltoexploreanythingfrompaintmanufacturetoradiology,anddevelopingskillsthatonewouldnormallybetrainedinwhilstworkingordoingpostgraduateresearch.Thesemaybesoftskills,but theyareessentialones,andonesthat donot come irst in the academic route but eitherlater during postgraduate study , or sometimes not atall. Whilst the scienti ic knowledge acquired isunpredictable and cantherefore only be tested viacoursework, the course doesinclude hard scienti icknowledgeandamathematicalrequirement.Insteadoftestingfacts, the exams focus oncritical and creative problem‐solving using taught scienti ictechniques, methodology andrigour, engaging in principlesratherthancrammedfacts.Inmyopinion,theappliedsciencecourseopensthedoortoaperspectiveofsciencedifferent fromthe true/falseblack/white image that puts off many children whowouldmakevaluablescientists.Insteadit isresourcefulandimaginative,likeahardcrosswordpuzzlethatsucksyou in andmakes you determined to inish it. I wouldargue that by eliminating applied subjects we are notmerely underserving the less academic students, buteverybody,reducingthegaininappliedskillsthatare,intherealworld,asvaluableasacademicones.Infact,weare underserving them already, because studentscapable of taking the traditional subjects are steeredaway from considering applied ones on theunderstandingthattheywilllowertheirtradingvaluebystooping to soft subjects. In school, Iwouldneverhavetakenanappliedlesson,andyetIwouldhavelovedtheindependent learning and practical dimensions andthrivedunder it. And if I’d never taught, Iwouldneverhave read the courses and reconsidered the hard/softsubjectstory.

Wider implications There are other ways I think in which these changesunderserve–andthatissocioeconomically.Nowthatallstudentshave todoA levels,by limiting thebreadthofsciencesandscienceskillsweareindangerofcreatingabottle‐neck.Subjectslikephysics,chemistryandbiologyprepare students to go touniversity and studyphysics,chemistry, biology or medicine or biochemistry , but

nottogetjobs.Thesestudentsarestillmissingmostjobskills.Sotheyhavetogotouniversity.Andthosewhodoless well in traditional subjects and get lower gradeswon’t get university places or won’t embrace theexperience; they will be stuck, in a climate with massunemployment and not enough apprenticeships,with abunchofAlevels,noworkingskillsandnoexperience.The traditionalway to get out of this scenario is to dovolunteerwork,but thiscreatesanothersocioeconomicproblem–classdivide.Whilst thewelloffcanaffordtodo endless internships for free whilst paying for theirown food and travel to gain invaluable industryexperience, many can’t, especially when faced with

pressures such as family illnessor children of their own andthe less well off and less wellquali ied tend to have babiesyounger . This can only haveone consequence: thediminution of the worth of thedegree, and a one‐route‐to‐any‐careermentality, forcingpeopleto go back and retrain or buyback into the old‐fashionedcareer‐for‐lifeprospect.

Although some exam boards are planning to overhaultheenvironmentalsciencecourseinthehopesofsavingit from the ruthless sword of Ofqual, it remains underthreat, whilst applied science is almost certainlydoomed.Newchangesto laboratorysessionsalsomeanthat therearenopractical exams,onlya labquota thatteachersmustsignoff.Crucially,thismeansthatpoorerschools with fewer resources can and will do fewerlabs, redistributing their budgets to save on sciencepracticalsandsoproducestudentswith lessexperienceand less complete understanding than their privatelyschooledpeers–and this, inmyopinion, is thekindofconsolidating understanding that makes all thedifference in university interviews and bridging theschool‐universityleap.This is well summarised by the Wellcome Trust, who,afterconsultationwithOfqualontheirproposalsforthediscontinuation of some subjects, asked, “Who choosesto study them?” Ofqual: GCSE reform consultationResponseby theWellcomeTrustAugust2013;https://wellcome.ac.uk/sites/default/ iles/wtp055604.pdf .Byreducingaccesstoenvironmentalandappliedsciencecourses or abolishing them, we thus risk exacerbatingsocial divisions, as well as reducing the life chances ofstudentswhoarelesswelloff.

the applied science course opens the door to a perspec-tive of science ... that is re-sourceful and imaginative, like a hard crossword puzzle that sucks you in and makes you determined to finish it.

https://wellcome.ac.uk/sites/default/files/wtp055604.pdf





Twenty-nine delegates attended this ECG event on 14 November at Burlington House. The aim was to provide a supportive environment for doctoral and postdoctoral researchers and early career scientists in industry to present recent research findings, network with fellow early career researchers, and hear about the career opportunities available to professional environmental chemists. Eight oral and eleven poster presentations were made by early career researchers. Themeeting startedwith a presentation fromKaterinaKademoglou Reading University on a novel analyticalmethod, which used a dialysis membrane containingTenaxtomeasurethebioaccesibilityof lameretardantsinindoordust.HelenBalshaw SwanseaUniversity thendescribed the possible use of pyrene – a luorescentprobe – to examine the polarity and viscosity of theorganic environment in water repellent soils, andAbdolbaset Karim University of Nottingham reportedon an investigation of 129I bioavailability in vegetablesgrowninsoilstakenfromNorthernIraq.Acoffeebreakprovidedanopportunityfordelegatestoview and discuss the posters, whose contents rangedfrom soil micronutrient de iciency to organic pollutantuptake by plants, and the fate of plasticisers andpharmaceuticals in the environment.Aposter by SaeedAhmad UniversityofNottingham onthegeochemistryof iodine and selenium in North East Pakistan wasjudgedtobethebestposterondisplay.The meeting proceeded with former ECG committeememberDr CeciliaMcLeod DirectorGeo‐Environment,WYG Global Consulting describing her work as anenvironmental chemist in ameliorating a toxic waste

dumpgeneratedbyIrishSteelonHaulbowlineIslandinCorkHarbour,Ireland.The irst afternoon session heard presentations onevaluating land ills for theirresourcepotential StevenWarwick, Cardiff University ; examining the effects ofphysicochemical parameters on the bioavailability ofmetals and hydrocarbons in soil mesocosms SabrinaCipullo, Cran ield University ; and on the coupling ofphyto‐ and myco‐remediation on petroleumcontaminated soils in the Niger Delta, Nigeria UdemeDickson,NottinghamTrentUniversity .The inalsessioncommenced with a presentation by Heather SandersNottinghamUniversity on the interactions of 129I and

77Se with humic acids, followed by AlunJames’ Aberystwyth University account of the use ofbiochar derived from reeds to treat minewater in anuplandenvironment.Alun’spresentationwas judged tobethebestoralpresentationofthemeeting.The meeting concluded with Professor Chris CollinsReading University recalling his life as anenvironmental chemist in an academic environment. Inparticular, he emphasisedhis interests in theuptake oforganic chemicals by plants; the fate and transport ofpollutantsinsoils;andtheuseofahumangutsimulatortomeasurethebioavailabilityofsoilcontaminants.

Saeed Ahmad receives his prize for the best posterpresentation.

Meeting report

Early careers researchers meeting on the environmental chemistry of water, sediment and soil Steve Leharne (University of Greenwich, [email protected]) and Tom Sizmur (University of Reading, [email protected])


A team of ten young scientists helped out at the NERC “Into the blue” environmental science showcase event in Manchester during half-term in October 2016. These are our experien-ces of the five days of demonstrations and talking to the public, and our motivations for sharing our enthusiasm for the subject with parents and children. The Natural Environment Research Council NERC organisedalargeoutreacheventthisyear.Thisfollowedthe success of allowing visitors on board the NERC’sDiscovery research vessel last year, whilst it wasanchoredintheThamesinLondon.Thisyear,membersof the public were allowed to inspect the NERC’sdedicated aeroplane for atmospheric and oceanicresearchatManchesterairport.Inanadjacenthangar,ahost of environmental science outreach activities andstallswereondisplay.Thewholeeventattractedmuchmedia interest BBC Newsround, Sky News and BBCeveningand regionalnewsprogrammes . Justover ivethousandmembers of the public visited over ive days,and two hundred stakeholders and VIPs attended theeveningevents.Each of the ive NERC research centres had beenencouraged to come upwith an idea for a stall for the

exhibition.Ourteamdecidedonageneralenvironmentalchemistrytheme,whichincludedsomeofthesuccessfulactivities we had used for previous RSC‐sponsoredoutreachactivities:1 Ocean acidi ication adding dry ice to an alkalinesolutionandseeingtheindicatorchangethepHtoacid .2 Soil testing pickingoutmicroplastics in thesoilandinvestigating themwith a smart phonemicroscope andthentestingthesoilforpH,nitratesandphosphates .3 Introducing zeolites to extract Fe‐ or Co‐contaminatedsolutions.4 Atmosphericchemistry smallsensorsmeasuringairpollution .ThevolunteerswererecruitedthroughECGsocialmediaplus friends and colleagues, and ranged from teachers,science communicators, environmental consultants, anundergraduate, a PhD student, an early career RSCcommitteemember, andpost‐doctoral researchers.TheRSC NW region education of icer, Charlotte Still, alsojoinedin.Weallshareda latlocally,soenjoyedtheraredowntimewe had at the end of the long days.Wewillkeep in touch for future outreach opportunities as theteamworkedwelltogether,andeachindividualbroughttheirownperspectivetothedemonstrations.

Volunteers’ impressions Callum Taylor I am currently on my placement year of my degree inForensic and Analytical Science at the University of

RowenaFletcherWood,ZoëFleming,BethDowler,MatthewSavageandMariosPanagiwereamongthevolunteerswhohelpedatthestall.

Outreach

Environmental chemistry team at the NERC “Into the blue” public event Zoë Fleming (University of Leicester, [email protected])

EloisedeSpretter,NikitaBhallaandCallumTayloralsovolunteered.Twoothervolunteers,AliceUghiandCharlotteStill,arenotinthephotos.


Hudders ield.IhavebeenamemberoftheRSCforoverayearnow,andIjumpedatthisopportunitytovolunteerforafewdays.Insomeareasofscience,keepingthepublicinvolvedandupdated with developments in specialised research isperhaps not too important. However, in theenvironmental sciences, it is crucial because everyone,fromachildinprimaryschooltotheCEOofaFTSE100company, contributes to the environmental challengesfacedbysociety.Outreacheventssuchas“Into the blue”stimulate interest andawarenessamong thepublic andevenamongotherscientistsaboutthistopic.Thiseventopenedmyeyes to the scaleof environmental researchin the UK, particularly the monitoring programmes inoceanic and atmospheric research. I also found theBritishAntarcticSurveystallverystimulating.VolunteeringfortheECGatthiseventhasshownmethevarietyofcareerpathsavailabletotheyoungerscientist.Forexample,monitoringpollutionor inding innovativesolutions to handling disposal. I learnt thatcommunicating your scienti ic discoveries to the publiccan be dif icult due to varying levels of education andinterest. To engage younger generations with scienceandtheenvironmentwithdemonstrationsandfunhands

on experiments, such as our dry ice experiment, willsurelyspark interest forsomeof themtocontinuewithsciencelaterinlife.Intermsofmyowncareer,thiseventhasshownme that therearemanypathsavailable,andso being bound to a rigid plan for the future is notnecessarilymorebene icialthana lexibleone.ToadaptJohnDonne, it isnooneperson’sduty to lookafter theearth,itisallofours.

Eloise de Spretter I graduated in July with integrated Masters Degree inEnvironmental Science, and am now working in theagriculturesectorasascienti icdataadministrator.

I too jumped at this chance to help with theEnvironmentalChemistryGroup’sstandatthe“Into theblue”event.Itwasanexcitingopportunitytotalktothepublic about something I careabout, and tomeet thoseconducting research in the environmental sciences.Communicating science to the public is extremelyimportantandalsochallenging.Thisisparticularlytrueof environmental science, which incorporates so manydifferent concepts. “Into the blue” succeeded incommunicating these ideas to the public, through fun,gamesandhands‐onexhibits. AttheECGstand,Ifoundchildrenwereexcitedtodiginthesoiltoseewhattheycould indandwereasking,“Howdidplasticgetthere?”Parents asked what they personally could do to helpmakeadifferenceandreducetheamountofplasticsthatendupinouroceans.Manypeoplecommentedthattheevent had opened their eyes to a whole world ofenvironmental challenges that they had not consideredbefore.It wasn’t just visitors who had the chance to see theresearchpresentedatthisevent; Ihadanamazingtimemeeting and speaking to the other exhibitors. Iparticularly enjoyed the tour of the NERC researchaeroplaneandvisitingtheBritishAntarcticSurveystall,where you could see the amount of preparation, work,

time and effort that takes place before an expedition.Sometimes studying the environment can feel all doomand gloom. However, this event has inspired me and Ibelieveitinspiredmanyofthevisitorstoo.

Further information NERC research aircraft in Manchester in the News:http://www.bbc.co.uk/news/video_and_audio/headlines/37770945NERC’s“Intotheblue”website:http://intotheblue.nerc.ac.uk/manchester/

Callumdemonstratestheoceanacidi icationdemo. Eloisehelpschildrentotestsoilforpollution.

http://www.bbc.co.uk/news/video_and_audio/headlines/37770945




http://intotheblue.nerc.ac.uk/manchester/


This interactive, public event was hosted by Science Oxford and the ECG. It took place in Lady Margaret Hall, Oxford, on Monday 21 November 2016 and was attended by thirty-two participants. The event diverged from other events by making use of interactive technology and by encouraging academic speakers to speculate about the future based on their expert knowledge. The audience was able to steer the direction of the debate and explore possible futures. Imagine yourself a hundred years in the future. Nofurther changes have been made to mitigate climatechange and we are now in anenergycrisis,placeslikeOxfordare looded continuously, andfood scarcity is a globalproblem. What can we do toaddress and prioritise theseissues?Atthestartoftheevent,each speaker gave a 5‐10minutetalkor“pitch,”followedby an audience vote usingTurningPointhandsets–an interactive technology thatallows live vote collection and data display inPowerpoint presentations. Following the revelation ofthe votes, the speakers responded, and the story of thefuture’scrisisunfolded.SpeakingattheeventwereDrCasparHewett NewcastleUniversity ,ProfessorMylesAllen UniversityofOxfordEnvironmental Change Institute , and Dr MarcusSpringman Oxford Martin School . The event waschairedbyDrMichaelaLivingstonefromOxfordSparks,a public engagement platform for science at theUniversityofOxford.Dr Caspar Hewett irst put forward the case for bothlarge‐andsmall‐scale loodinterventions,fromdrainingreservoirs before predicted heavy rainfall and digging

holes to divert excess water and delay its entry intorivers, to planetary‐scale geoengineering approaches.The two geoengineering methods that he supportedwere the use of “Salter’s ships” spraying seawater intotheairto increaseEarth’salbedo,therebyre lectingthesun’s rays back into space and cooling the planet, andCO2 sequestration using arti icial trees for moreinformationongeoengineeringseetheJuly2016editionoftheBulletin,whichreportsontheDistinguishedGuestLectureonthistopicheldinMarch2016 .Thebene itofthese technologies, Dr Hewett argued, was that theyunlike other proposed geoengineeringmethods couldbe turnedoff at any time,werewe to realise that theirnegativeeffectsoutweightheirpositiveones.Professor Myles Allen took a rather unusual stance onenergy,arguingthatthepublicshouldnotfootthebillormaketheefforttosaveenergy.Instead,weshouldcreatepressure and convince government to make energy

companies responsible formitigating the CO2 they putout into the environment –not by paying a carbon tax,butbymitigatingallofit.Thismitigation could be done byplanting arti icial or realtrees, or through under‐ground carbon storage innatural rock cavities. On the

other hand, Professor Allen argued against theintroductionofgeoengineeringviaalbedochanges:“It’llnever catch on”, he declared, outlining the problemsassociatedwithswitchingitoffagain,aswellascon lictsover governance and the varying effects that it wouldproduceacrosstheworld.Dr Springman’s arguments for a food‐based focusinitiallyalsocenteredonclimatechangemitigation.Thespeaker argued for a reduction in methane emissions,whichcontributearoundaquarterofthegreenhousegaseffect because methane is a much more potentgreenhouse gas than carbon dioxide. He proposedseveralsolutionsforthis,beginningbycuttingredmeatconsumptionby10%toseea fall inmethaneemissionsby20to30%andaconcomitantimprovementinpublichealth.

Meeting report

Masters of disaster – click to change the world Rowena Fletcher-Wood (Science Oxford, [email protected])

Professor Allen declared the ener-gy problem virtually fixed, with no more net CO2 emissions and with clean-up underway via the already

proposed artificial trees.


In the initial audience vote that followed these pitches,theproposedenergymeasuresobtainedthemostvotes,with food interventions a close second and loodinginterventions trailingbehind Figure1 .ProfessorAllendeclared the energy problem virtually ixed, with nomorenetCO2emissionsandwithclean‐upunderwayviathe already proposed arti icial trees. Dr Hewettbemoaned the widespread disasters that would resultfrom neglecting looding, causing him to propose hissamemeasuresagain.Followingthe irstvote,DrSpringmanfocussedmoreonthe human health element of meat consumption andargued for taxing foodstuffs according to their healthimpactsandmethanecontent.Sucha taxwouldheavilyincentivise micronutrient‐rich diets, with signi icantlylowermeatanddairyconsumption,escalating thepriceofaburgertoaround£30.Thissuggestion,however,wasnotpopular.Thesecondroundofvotingsawaswinginthe opposite direction, with overwhelming support forloodinginterventions.However, the vote rapidly yo‐yoed again aftergovernance issues in geoengineering were explored inmore depth, “Meat freeMondays”were introduced andDrSpringmanwentontoproposeimprovingsustainableeating education to caterers, especially in schools,including choosing foodwith health bene its and lowercarbon footprints. The audience were quite taken withthis softer approach in the third round of voting;however, Dr Springman argued during questions thateducation actually has a negligible impact given theresources that go into it, and that taxation, howevermuch we may like burgers and dislike taxing theirconsumption,isactuallymuchmoreeffective.ProfessorAllenendedbyproposingarescuemissionforGreenland. He argued that, given delays ingeoengineering and carbon cleanup according to thevote,theicemaynowbemeltingatacriticalrate,riskingsealevelrisesofupto20meters,causinghugelossesofland worldwide well beyond the localised looding weheard about earlier, changing sea temperatures anddevastatingecosystems.Ending on “a silly note”, Dr Hewett proposed meetingloodingissueshalfway,abandoningcitiesthathadbeenaffected and developing new island colonies thatemployedVenetian‐styleoceantransport.The inalvotesaw46% for “waterworldadaptions”and32% to saveGreenland Figure1 .Whilstthevotingpatternsappearindecisive,theymightalsoindicatethatallissuesweresimilarlyimportant.Butthiswasnot the last vote: no eventwouldbe completewithoutevaluationdata,andthehandsetscameinhandy

forcollectinginformation.44%oftheaudiencevotedtheeventexcellent,and25%admittedtheyhadneverbeento a science event before. Attendeesweremostly local,with 87% coming from Oxford/Oxfordshire, 10% fromfurther a ield, and 3% from abroad, most havingconnected to the event through Oxford University orScienceOxford. Science Oxford runs a year round programme of eventsfor adults and families, which can be explored atscienceoxford.com/events.

Figure1.Votesfromthefourrounds.


The use of rare earth elements (REEs) in industrial, medical and consumer products is increasing rapidly. REEs are important components of the new technologies such as wind turbines and electric vehicles, that are vital to the transition to a low carbon economy. Because of their chemistry and speciation, REEs are rarely present in a form that can cause toxicity, but REE concentrations are noticeably elevated in surface waters and sediments globally. This article explores the current and future uses of REEs and discusses the possible environmental impacts of REE emissions. REEs, also known as the lanthanide elements, are agroup of 15 elements with atomic numbers 57 to 71Figure1 .Despitetheirname,theyarenotparticularlyrare.Forexample,Ce themostabundantREE ismoreabundant than Cu or Pb and several REEs are morecommon than Sn, Mn, Ag or Hg. The REEs often occurtogetherbecausetheyarechemicallysimilar allhaveanoxidation state of 3 , have similar ionic radii and allinhabit the same row in the periodic table , whichenables them to substitute for each other in crystals.There is, however, a small but consistent decrease inionic radius with increasing atomic number whichoccurs alongside a decrease in abundance. REEs withatomic numbers 57 to 63 are considered light REEsLREEs while thosewithatomicnumbers64 to71areconsideredheavyREEs HREEs .TheREEswithaneven

atomic number are more abundant than REEs with anodd atomic, according to the Oddo‐Harkins rule thatdescribesprotonpairingduringstarformation.PureformsofREEstendnottoexistintheenvironmentbecause they are very reactive and form part of thecrystalline lattices of minerals. Even after weathering,they are usually incorporated into secondary mineralsand remain immobilised. Many REEs were originallyisolatedinthe18thand19thcentury,butonlyef icientlyinthe20thcentury.ApartfromCe,La,andNd,REEswerenot commercially available until 1940s. Themarket forREEs has arisen in the last ifty years, and demand isexpected to increase exponentially in the next twenty‐ive years. Up until 1985, most REEs originated frommineralsminedatMountainPassinCalifornia.However,China emerged as amajor producer in the 1990swithextraction of REEs from ores located at the BayanOboIron deposit, Inner Mongolia. As a result, China nowsuppliesmorethan90%oftheglobaloutputofREEs.ThepropertiesofREEsareexploitedtoproduceawiderange of consumer products. REEs have been used inChina in fertilisers and as feed additives for livestock.There is some evidence linking this application toincreasedcropyields,andtogainsinanimalbodyweightand enhanced milk/egg production 2 . REEs areincorporatedintocatalystsforpetroleumcrackinginoilre ineries.Ceriumcarbonateandceriumoxideareusedin diesel fuel additives and in catalytic converters,resulting in thereleaseofCeO2nanoparticles invehicleexhausts. Phosphors for luorescent lighting containseveral REEs Tb, Ce, and La for green and blueemissions, and Eu for red emission . However, theenvironmental impact of REEs in these phosphors isoftenoverlookedbecause they also containHg, used toproducenaturalwhite light. SomeMRI contrast agents,e.g.gadopenteticacid,containGdasacomplexion.Oral

Article

Rare earth elements: Chemistry, fate and environmental impact Tom Sizmur (University of Reading, [email protected])

Figure1.Thelanthanidesandactinoidsarereferredtoasrareearthelements.


or intravenous administration of the contrast agentresultsinurinaryexcretionoftheabsorbedGd,whereitenterswastewatertreatmentplants seebelow .Severalapplications of REEs are a direct result of legislation toimproveairquality e.g.Ceincatalyticconverters orthetransitiontoalowcarboneconomy.Forexample,Nd,Dyand Sm are used in themanufacture ofmagnetic alloysfor hybrid engines and in permanentmagnets forwindturbines as well as a whole host of consumer electricgoods such as headphones, computer hard drives, andelectric motors . Nickel‐metal hydride rechargeablebatteriesforelectricandhybridvehiclesmaycontainLaCe,Nd,orPrastheanode.

Environmental fate Therearevery fewstudiesof theenvironmental fateofREEs.Because theyareconsidered less toxicthanmanyother elements e.g. As, Cd, Cr, Hg, Pb , theenvironmentalimpactofREEsisoftenovershadowedbythese other elements. Forexample,whenREEore ismined,themajor hazards are associatedwithothertoxicmetalspresentintheREE‐bearingoreandinwastestreams. Waste materials fromREE processing are naturallyradioactiveduetothepresenceof,for example, thorium anduranium radioisotopes. Clean‐upcosts for spillages of radioactivewastewater from the processingof REE ore at the Mountain Passmine inCaliforniacontributedto itsdeclineandclosurein the 1990s. Despite these hazards, REE mining isgenerally considered to have a low environmentalimpact. REEs tend to be present in carbonatemineralsrather than in sulphides, meaning that acid minedrainage is less common at REE mines than othermetalliferousmines.TheimpactontheenvironmentfromtheuseofREEswasirst detected in the early 1980s. Analysis of sedimentcores collected from the San Pedro Shelf, just south ofLosAngelesinCalifornia,revealed890‐6900timesmorelight REEs La, Ce, Nd and Sm than present in crustalmaterial 3 . The REEs were traced to a wastewateroutfalldischargingintothebasinthatserved3.5millionpeople, tens of thousands of businesses and industries,and, importantly, seventeen oil re ineries. Mostwastewater is discharged into rivers where REEcontaminants may be deposited on land during loodevents or carried out to sea. About 1.5 tonnes ofanthropogenicLa isdischarged into theNorthSea fromthe river Rhine every year. The source of this

contamination is an industrial plant near the city ofWorms in Rhineland‐Palatinate, which uses luidcatalyticcrackingagents.Laconcentrations 49ppm inthe plant ef luent exceed levels known to causeecotoxicologicaleffects 4 .Gadolinium from MRI contrast agents is the mostubiquitous REE discharged into rivers via wastewatertreatment plants. The relatively stable Gd complex issoluble in aquatic ecosystems. As a result, in luent andef luentofwastewatertreatmentplantsisoftenenrichedinGd, but an elevatedGd concentration is not found insewage sludge. Nozaki et al. 5 found evidence forelevated Gd concentrations in three rivers, whichdischargedintoTokyoBay.Theyconcludedthatnotonlypopulationsize,butalsothedegreeofmodernisationofmedical treatments affects REE enrichment in theenvironment. It has been suggested that, due to itssolubility and ubiquity, Gd could be used as a tracer of

other emerging contaminantsdischarged from wastewatertreatmentplants,whicharemoredif icult to analyse, such aspharmaceuticals or personal careproducts 6 .InanecologicalriskassessmentofREEs on aquatic organisms inrivers, ecotoxicity tests wereperformed for several aquaticinvertebrates. From the dose‐response curves, Predicted NoEffect Concentrations PNECs

were computed for Ce, Gd and Lu. These PNECs wereused to produce risk quotients by comparison with aglobal dataset of REE concentrations in rivers 7 . Riskquotientswereabove1 for some locations e.g. ef luentfrom a wastewater treatment plant downstream of ahospital or residential area , indicating that REEswerepresentatconcentrationsabovetheirPNECs.

Toxicity Because REEs are chemically similar, onemight expecttheirecotoxicologicaleffectsalsotobesimilar.However,a current lack of knowledge on the mechanisms oftoxicity of REEs precludes this assumption. Mostecotoxicology studies have focused on freshwaterorganisms,andthereareonlyafewpublishedsaltwaterorterrestrialstudies 8 .Toxicityseemstodecreasewithincreasing atomic number due to higher stabilityconstants of the heavier REEs, indicating that thespeciation of the element is of greater importance thanits chemical identity. The in luence of speciation andthusbioavailability ontoxicityisparamountastheREEs

Toxicity seems to decrease with increasing atomic

number due to higher sta-bility constants of the heav-ier REEs, indicating that the speciation of the element is of greater importance than

its chemical identity.


areusuallypresentinthe3 oxidationstatesotheycanform soluble complexes with nitrates, chlorides, andsulphates. In highly complexing media, REEs forminsoluble species with carbonates, phosphates andhydroxides, which means their toxicity could beunderestimated in these solutions. REE complexesbecome less soluble with decreasing temperature andincreasing pH or redox potential. Thus, chemicalspeciationmodellingisrequiredtoestimatethefreeionconcentrationinsolutionsandtopredicttoxicity.Most toxicologicaldata relate toCe andLa,with a littleinformationonGdandNd,butvirtuallynothing for theotherREEs.REEshavea similar ionic radius to calciumand so can replace Ca in cell functions or block Cachannels.However,themostwidelyreportedmechanismof toxicity is a redox imbalance in cells that leads tooxidative stress. Several studies have used reactiveoxygen species ROS or antioxidant activitiessuperoxidedismutase, catalase,andglutathioneperoxidase asatoxic endpoint 9 . There arereports that REEs have a bene‐icialeffectatlowconcentrationsand adverse effects at higherconcentrations hormesis . Forexample, the stimulation ofantioxidant enzymes in plantswith low La levels could beinterpreted as a toxic response,but theeffecthasbeen found tobe positive at low concentra‐tions,helpingtheplanttodefendagainst ROS caused by other stresses 8 . This me‐chanismmayberesponsiblefortheincreasedcropyieldandlivestockgrowthratesobservedinresponsetoREEadditionstofertilisersandfeedadditivesinChina 2 .Relatively little attentionhasbeenpaid to theeffectsofREE exposure on human health. Studies have primarilyfocused on monitoring populations who reside next toREEmines inChina.An investigationof residents livingclose to the Bayan Obo Iron deposit in Inner Mongoliafound REE levels in hair samples above those from acontrol area 10 . Concentrations were higher in malehairthanfemale,andhigherinminersthannon‐miners,indicating occupational exposure. Accumulation of thelightREEsalsoincreasedwithage,whichsuggestsaslowexcretion rate and the potential for bioaccumulation. Asimilar study conducted in a large‐scale mining arealocated in Hetian Town of Changting County, FujianProvince, Southeast China showed that REEs frommining were present in the soil, water and vegetablesproduced in the vicinity of the mine, and these wereassociatedwith elevated concentrations in the hair and

bloodof local farmers 11 .Ariskassessment indicatedthat the ingestion of contaminated vegetables did notexceedvaluesknowntobehazardousforhumanhealth,butthatlongtermexposureshouldbeconsidered.

Recycling and recovery Chinaproducesmorethan90%oftheglobalREEoutputand imposes a quota on the export of REEs. Thisrestriction is encouraging the recovery and reuse ofREEs.Lessthan1%ofREEsin‘end‐of‐life’productswererecycled in 2011, but there is considerable scope forrecycling the REEs used in permanent magnets, lampphosphors, rechargeable batteries and catalysts 12 .Because REEs usually occur together in a ixed ratio,somemaybestockpiledwhilethereisahighdemandforothers, and thus their demand is controlled by theelementinmostscarcesupply.Forexample,becauseNdismuch less common than La or Ce,mining ore forNd

produces an over‐supply of Laand Ce. Future demand forelectric vehicles and windturbines will rely heavily on Dyand Nd, which are used inpermanent magnets. Becausethesetechnologiesareimportantcomponents of our strategy totransition to a low carboneconomy,thesupplyofREEshasbeen highlighted as critical toachieving carbon neutrality. Ithas been predicted that thesupplyofDyandNdwillneedtoincrease by 700% and 2600%,

respectively,between2010and2035ifatmosphericCO2istobestabilisedat450ppmusingcurrenttechnologies13 . The REEs of greatest concern are therefore thosethatareofhighimportancetocleanenergyandalsohaveahigh supply risk Nd,Dy,EuandTb .Oneof thebestopportunitiesforrecyclingispermanentmagnetswhichare based upon neodymium‐iron‐boron NdFeB alloysandalsocontainDy,Pr,GdandTb,representingsomeofthe most critical REEs in terms of future supply risk.There are also opportunities for recycling REEs fromnickelmetal‐hydridebatteriesandlampphosphors.Severalstudieshavesoughttoidentifytheopportunitiesfor recovering REEs from mixed waste streams.Commercially recoverable quantities of REEs, primarilyCe,havebeendetectedinland illsbyGutiérrez‐Gutiérrezet al. 14 , but recovery would only be economicallyfeasible if other valuablematerialswere also recoveredsimultaneously.Bottomand lyashfrommunicipalsolidwaste incineratorsmayprove tobeapromisingsource,as strong enrichment of Eu, La, Gd, and Tb correlates

Less than 1% of REEs in ‘end-of-life’ products were

recycled in 2011, but there is considerable scope for recy-cling the REEs used in per-

manent magnets, lamp phos-phors, rechargeable batteries

and catalysts


withphosphoruspentoxide P2O5 andindicatesthatthesourceofREEanomalies in theashare likely fromREEphosphors present in luorescent materials 15 . REEswerefoundtobepresentatseveralordersofmagnitudehigher in acidmine drainage water than natural water16 presentinganopportunitytoprovideamodestbutcontinuoussupplyofpotentiallyvaluableresourcesasaby‐product of otherwise costly remediation activities.SewagesludgeonlyseemstobeapromisingsourceofGdthough presumablydue to itsuseasaMRIcontrastingagent , since other REEs show enrichment factors nearunityindicatinggeogenicorigin 17 .The maturation of technologies for recovering REEsfrom waste streams and recycling them in ‘end‐of‐life’products may result in lower concentrations releasedinto environmental media. However, this must becontrastedagainstananticipatedexponentialgrowth intheiruse in consumableproducts. It isunlikely that theenvironmentalimpactofREEs,whichseemstobelowerthanmanyothermetallic elements,will drive increasesin recycling and recovery. Therefore, the adoption oftechnologiestoexploit“second‐hand”REEresourceswilllikely be dependent on the price of REEs on the globalmarket. References 1. ECG Bulletin, July 2013, pp. 3‐5 and pp. 10‐20, see

http://www.rsc.org/images/ECG‐Bulletin‐July‐2013_tcm18‐233368.pdf.

2. G. Pagano et al., Rare earth elements in human andanimal health: State of art and research priorities,EnvironmentalResearch142,215‐220 2015 .

3. I. Olmez, E. R. Sholkovitz, D. Hermann, R. P.Eganhouse, Rare earth elements in sediments offsouthern California: a new anthropogenic indicator.Environmental Science & Technology 25, 310‐3161991 .

4. S.Kulaksız,M.Bau,RareearthelementsintheRhineRiver, Germany: irst case of anthropogeniclanthanum as a dissolved microcontaminant in thehydrosphere,EnvironmentInternational37,973‐9792011 .

5. Y. Nozaki, D. Lerche, D. S. Alibo, M. Tsutsumi,Dissolved indium and rare earth elements in threeJapanese rivers and Tokyo Bay: evidence foranthropogenic Gd and In, Geochimica etCosmochimicaActa64,3975‐3982 2000 .

6. P. L. Verplanck et al., Evaluating the behavior ofgadolinium and other rare earth elements throughlarge metropolitan sewage treatment plants.EnvironmentalScience&Technology44,3876‐38822010 .

7. V. González et al., Lanthanide ecotoxicity: First

attempt to measure environmental risk for aquaticorganisms, Environmental Pollution 199, 139‐1472015 .

8. V. Gonzalez, D. A. Vignati, C. Leyval, L. Giamberini,Environmental fate and ecotoxicity of lanthanides:are they a uniform group beyond chemistry?,EnvironmentInternational71,148‐157 2014 .

9. G. Pagano, M. Guida, F. Tommasi, R. Oral, Healtheffects and toxicity mechanisms of rare earthelements—Knowledge gaps and research prospects,Ecotoxicology and Environmental Safety 115, 40‐482015 .

10.B.Wei, Y. Li, H. Li, J. Yu, B. Ye, T. Liang, Rare earthelementsinhumanhairfromaminingareaofChina.EcotoxicologyandEnvironmentalSafety96,118‐1232013 .

11.X.Li,Z.Chen,Z.Chen,Y.Zhang,Ahumanhealthriskassessment of rare earth elements in soil andvegetables from a mining area in Fujian Province,Southeast China, Chemosphere 93, 1240‐12462013 .

12.K.Binnemansetal.,Recyclingofrareearths:acriticalreview, Journal of Cleaner Production 51, 1‐222013 .

13.E. Alonso et al., Evaluating rare earth elementavailability:A casewith revolutionarydemand fromclean technologies, Environmental Science &Technology46,3406‐3414 2012 .

14.S. C. Gutiérrez‐Gutiérrez, F. Coulon, Y. Jiang, S.Wagland, Rare earth elements and critical metalcontentofextractedland illedmaterialandpotentialrecoveryopportunities,WasteManagement42,128‐136 2015 .

15.V. Funari, S. N. H. Bokhari, L. Vigliotti, T. Meisel, R.Braga, The rare earth elements in municipal solidwaste incineratorsashandpromising tools for theirprospecting,JournalofHazardousMaterials301,471‐479 2016 .

16.C.Ayoraetal.,RecoveryofRareEarthElementsandYttrium from Passive‐Remediation Systems of AcidMineDrainage,EnvironmentalScience&Technology50,8255‐8262 2016 .

17.P. Westerhoff et al., Characterization, recoveryopportunities, and valuation of metals in municipalsludges from US wastewater treatment plantsnationwide.EnvironmentalScience&Technology49,9479‐9488 2015 .


In a previous issue of the ECG Bulletin, the editors wrote about the possible detrimental effects of neonicotinoids on pollinator populations and the impacts on biodiversity and human food security (1). In interviews with Dr Ben Woodcock (Centre for Ecology and Hydrology) and Professor Simon Potts (Reading University), I asked about the evidence supporting a risk to food security, and the role played by bees in pollination. About88%ofnutritionallyimportantfoodcropssuchasfruits,vegetables,nutsandseedcropsarepollinatedbyanimals 2 . Neonicotinoid impacts on pollinationservices will thus have widespread consequences forecosystems and species biodiversity, and also affecthuman food security. Animal‐pollinated plantscontributemostofthevitaminsandmineralsinourdiet.Thus, although calorie‐containing foods such as wheatandricearemostlywindpollinated,thenutritionalcoreofourdietcouldbethreatenedbyfallingbeenumbers ifbees,whichpollinate threequartersof theworld’s foodcrops,arerepresentativeofotherpollinatorspecies .Inhisinterview,DrBenWoodcockexplainedthathewaspart of the CEH cohort involved in a large‐scale,independent study of neonicotinoid impactscommissioned by pesticide giants Syngenta and Bayer3 . The study took place over one growing season ateleven sites in the UK, Germany, and Hungary, eachcontaining three sets of 40 to 70 hectare oilseed rapeields. The ield sizes were a compromise betweenhoneybee foraging ranges and the limits set byregulatory authorities when applying pesticides thatwereunderatemporaryban.Ineachsetofthree ields,one ield was planted with seeds treated withClothianidin, the second with seeds treated withThiamethoxam, and the thirdwith untreated seeds. Sixhoneybee hives, twelve bumblebee colonies, and iftycocoonsofasolitaryRedMasonbeewereplacedateachsite. The study sparked public criticism because of theperceived con lict of interest from using funding fromthepesticidegiantsSyngentaandBayer.Theresultshavebeensubmittedforpeer‐reviewpublication.

Simultaneously, Dr Woodcock contributed to a paperthat assessed the long‐term impacts of ield‐level dosesof neonicotinoids 4 . This paper applied statisticalmethods multi‐species dynamic Bayesian occupancyanalysis to 18 years of UK bee distribution data,spanning 62 species of wild bee and supplied by theBees,AntsandWaspsRecordingSocietyoftheBiologicalRecord Centre. This robust body of qualitative data iscollectedchie lybyamateurentomologistswithspeci icbeeexpertise.Beedistributionswerecorrelatedagainstthe locations of neonicotinoid‐treated oilseed rape anddemonstrateda relationshipbetweenneonicotinoiduseand large‐scale loss of populations, particularly amongspeciesthatforageonoilseedrape.As Dr Woodcock explained, this second study is avaluablecompaniontothe irstbecausesmallandlarge‐scale studies only jointly provide results that canelucidatethefullimpactofneonicotinoidsonpollinators.Many ieldstudiesarelimitedtorelativelysmallareasoftreatedcropsforpracticalreasonsandmaynotcapturethefullextentofbee‐neonicotinoidexposure,asbeescanforageoverlargeareas honeybeesregularlyforage2kmfrom hives . Other ield studies are limited to singlespecies. Across time scales of one to two years, naturalchanges in animal populations, weather conditions andvariationinrealworldagriculturalconditionsmeanthatmeasured responses may be dominated byenvironmentalconditions.Ontheotherhand,laboratoryand small‐scale ield experiments allow better controland replication that is not achievable in larger‐scalecorrelativestudies.Inthelattercase,itismuchhardertocontrol for environmental differences, and results areoften in luenced by a wide range of factors such asdestruction of habitats to produce ields for oilseedrape ,manyofwhicharenotunderinvestigation.Thisisaclassicproblemwithcorrelativestudies 3 .In his interview, Professor SimonPotts toldme that hewas seconded to the UN for two years to co‐chair areporton“Pollinators,PollinationandFoodProduction,”which evaluated the global evidence on the causes ofpollinator declines and identi ied effective policy andpractice responses tomitigate pollinator losses 5 . Healso took part in a study assessing the effects of aneonicotinoid on the pollination services thatbumblebees provide to apple trees, a crop of globaleconomic signi icance 2 . Under semi‐ ield conditions,pre‐exposure of bumblebees to 10 ppb Thiamethoxam

Article

Neonicotinoids updated Rowena Fletcher-Wood (Science Oxford, [email protected])


pesticideledtofewervisitstotheapple lowers.Thisnotonly meant less ef icient pollen collection, but alsoimpacted theapple trees, producing fewer seeds. Seedsareconsideredakeyindicatorofquality formostapplevarieties. The study suggested effectswere likely to beon the level of the bee colony, rather than individualbees. This could have serious implications for othercropsandecosystems.Professor Potts argued that if effects on bees can beextrapolated to other pollinators, these results couldhave worrying consequences. Loss of pollinators couldbe a major challenge for global food security, possiblyentirely driven by bees. Some foodstuffs like chocolateprimarilypollinatedbymidges andcoffeeontheglobalmarket could fall and couldreturn to being luxury, andconsumers would moregenerally have more limitedchoice and scarcer access tomicronutrientrichfoods.Thiscould have furthersociological effects, dividingconsumers between thoseable and unable to affordtheseproductsandincreasingthe risk of malnutritionamongst lower incomeearners, especially indevelopingcountries.Neonicotinoids contribute80% of the world’s seedtreatment market and 20% of the world’s pesticidemarket. Many crops that they are applied to, such asoilseed rape, cannot be easily grown organically. The“cabbage”ofcerealcrops,justaboutanythingeatsrape,making it a work‐intensive, low‐yielding crop to growwithout the assistance of pesticides. But this does notmean theeffectsofneonicotinoids cannotbemitigated.Overall pesticide use can and should be reducedworldwide. Professor Potts and Dr WoodcockrecommendedanIntegratedPestManagementapproachthat combines pest monitoring with a range of pestcontrol methods, such as crop rotation, ield marginmanagement, and biological control 6 . This meansreforming our paradigm of pesticide use and movingaway from continuous prophylactic application to last‐resort use only when other strategies are insuf icient.Another way to reduce risk is with new technologies,such as reduce‐drip nozzles on pesticide sprays tominimisewasteandavoidhighconcentrationdrops 6 .Buttheseinterventionsmaynotenoughontheirowntoprotect bees and other pollinators. Professor Potts andDr Woodcock suggest that ecological intensi ication of

farmingcouldmakeasigni icantdifference.Thismeansworkingalongsidebiodiversitytoincreasesoilandcropfertility, such as by creating land strips populated bywild lowersandsupportingbene icialinvertebrates 7 .Research suggests that even if you takeout8%of landfor theseuses, theboost innativebiodiversitymeansaboostinpollinationandnaturalpredatorslikeladybirdsthateataphids,andinturnsustainableintensi icationofcrops–producingjustasmuchproduct 5 .Wecanalsohelp bees directly by supporting habitats, creatingnesting sites and introducing foraging resources thatfostermorerobustpopulationsbetterabletostanduptothepesticidestheydoencounter 7 .However, changeover requires work, and farmers are

naturally risk‐averse. It maybe that top down regulatorymethods are required toimplement ecologicalfarming. Some, like my vegboxproviders,haveturnedtoorganic farming instead, butthis has its own problems:organic farming usuallyrequires more land for thesame volume of produce andso is less ef icient, and asmost of our remaininguncultivated land is highvalue nature sites, thesefarms would be unable toexpand without causingfurther loss of habitat and

damagetonativebiodiversity.So it looks like promoting ecological intensi ication thekey – this doesn’tmean banning pesticides, but it doesmeanencouragingadjacentbiodiversityandusesmartertechnologyandmethods.

References 1. Howharmfulareneonicotinoidstotheenvironment?

ECGBulletin,July2015,pp.3‐4.2. D.A.Stanleyetal.,Nature528,548 2015 .3. NERC Centre for Ecology and Hydrology, A large‐

scale ield experiment to quantify the impacts ofneonicotinoids NNIs on honeybees andwild bees,Version2.1 4June2015 .

4. B.A.Woodcocketal.,NatureComm.7,12459 2016 .5. S. G. Potts et al., The assessment report on

pollinators, pollination and food production:summary for policymakers 2016 , seewww.ipbes.net/sites/default/ iles/downloads/pdf/spm_deliverable_3a_pollination_20161124.pdf

6. L.V.Dicksetal.,Science354,975 2016 .

Honeybeesreturntotheirhives.Recentstudieshaveinvestigatedtheimpactsofneonicotinoidpesticidesonhoneybeesandotherinsectpolli‐nators.Credit:Photogra iero/Shutterstock


Forthcoming meeting: ECG Distinguished guest lecture and symposium

Inside the engine: From chemistry to human health

When: Wednesday 1 March 2017

Where: Library and Council Rooms, The Royal Society of Chemistry,

Burlington House, Piccadilly, London W1J 0BA

Thisone‐daysymposiumorganisedbytheEnvironmentalChemistryGroupoftheRoyal Society of Chemistry explores the chemistry of diesel engines emissions,emissions policy, and how it's affecting human health. The 2017 ECG Distin‐guishedGuestLecturewillbeprovidedbyProfessorFrankKelly King’sCollegeLondon .Programme12.00LunchandCoffee13.00SymposiumisopenedbyECGChairZoeFlemingDrClaireHolman independentconsultant :"Dodieselvehiclescausepoorairquality?"DrHolmanwillprovidetheintroductiontotheseminar,speakingonthelinksbetweendieselandairquality,vehicleregulationsandgeneralemissionslegislation.DrJacquelineHamilton UniversityofYork :“Airpollutionandtraf ic:Searchingforthemissingemissions”DrHamiltonwillspeakonorganiccompoundsfrompetrolanddieselemissions.Manymoderncarsemitlevelsofnitrogendioxide NO2 aboveregulationswhendrivenunderrealworldconditions.Isthisalsotrueforsomeotherpollutantsemittedbyroadtransport?Thesespeciesaremuchmoredif iculttomeasure,butarecurrentlyseverelyunderestimated.Doweneedtolookagainatemissionstestingandurbanmonitoring?14.30Tea/CoffeeandtheECGAnnualGeneralMeeting15.30SymposiumresumesMrSimonBirkett CleanAirinLondon :“EmissionsPolicyandAirPollution”MrBirkettwillspeakonthehistoryoffavouringdieselfuelbasedonCO2emissions.Hewilladdressissuessur‐roundingemissionssurchargesandultralowemissionzonesandtheopportunityandneedtobandiesel,likecoalwasbanned60yearsago.ECGDistinguishedGuestLecture2017:ProfessorFrankKelly King’sCollegeLondon :"Traf icPollutionandHealthinLondon,UmeaandBeijing."Incitiesacrosstheglobe,roadtransportremainsan importantsourceofairpollutants thatare linkedwithacuteandchronichealtheffects.ProfessorKellywillspeakonhisworkoverthelast20yearsinvestigatingtheseassocia‐tionsinhumanchallengechamberstudiesinUmea,Sweden;real‐worldexposurescenariosinLondonandrecentlythelinkbetweentraf icemissionsandhealthinthemegacityBeijing,China.Hewillreviewhisgroup’s indingsandthosefromothergroupstoconvinceyouweneedtoadvancebeyondafossilfuelbasedroadtransportsystem.17:15meetingcloseReportsonthesymposiumwillbeincludedinthenextissueoftheECGBulletinJuly2017.Fees:EARLYBIRDbefore1stFebruary2017:£50/£35forECGmembers RSCmemberscanjointheECGforfree ;STANDARD£65/£50Registration:http://www.rsc.org/events/detail/24566/inside‐the‐engine‐from‐chemistry‐to‐human‐health

Credit:Olegusk/Shutterstock


Forthcoming meeting

What’s new in the analysis of complex environmental matrices?

When: Friday 3 March 2017

Where: Science Suite, Royal Society of Chemistry, Burlington House,

Piccadilly, London W1J 0BA

A joint mee ng organized by the RSC’s Environmental Chemistry Group, Water Science Forum, and Separa on Science

Group.

Programme9.00‐9.40amRegistrationandcoffee9.40‐9.45amGrahamMills UniversityofPortsmouth,UK :Openingandwelcometomeeting9.45‐10.15amLeonBarron King'sCollegeLondon,UK :Screeningofcomplexforensicandenvironmentalsamplesusinghighresolutionanalysisandinsilicodataminingtools10.15‐10.45amAndrewSweetman LancasterUniversity,UK :UseofpassivesamplersasapotentialcompliancetoolwithintheEUWaterFrameworkDirective10.45‐11.15amCoffeebreak11.15‐11.45amColinCreaser LoughboroughUniversity,UK :Combiningionmobilityspectrometrywithmassspec‐trometryfortheanalysisofcomplexsamples:thepotentialforenvironmentalanalysis11.45‐12.15pmStuartHarrad UniversityofBirmingham,UK :Brominated lameretardantsinwasteconsumerarti‐cles12.15‐1.00pm KeynoteLecture JaroslavSlobodnik EnvironmentalInstitute,SlovakRepublic :Non‐targetscreen‐ingofenvironmentalpollutantsinthecontextofriskassessmentofEuropeanriverbasins:theNORMANnetworkper‐spective1.00‐2.15pmLunchbreakandvendors’exhibition2.15‐3.00pm KeynoteLecture JacobdeBoer VrijeUniversiteitAmsterdam,Netherlands :Humanexposuretoenvi‐ronmentalcontaminants:directprobetime‐of‐ lightmassspectrometryrevealsamultitudeofchemicalsindoors3.00‐3.30pmGavinMills SevernTrentLtd.,UK :Advances in thedeterminationof tasteandodourcompounds indrinkingwater3.30‐4.00pmBarbaraKasprzyk‐Hordern UniversityofBath,UK :Howcanurbanwaterpro ilinginformourunder‐standingofthestateoftheenvironmentandpublichealth?4.00‐4.30 pmMark Perkins Anatune, UK : VOCmeasurements in ambient air using Selected Ion FlowTubeMassSpectrometry SIFT ‐MS‐automationandcalibrationconsiderations4.30pmRogerReeve UniversityofSunderland,UK :MeetingcloseAbstractsfromthesymposiumwillbeincludedinthenextissueoftheECGBulletinJuly2017.Fees:Members£90 andofBMSSorChromatographicSociety ;Non‐members£120.00;Students,retiredmembersandunwaged£25Registration:www.rsc.org/events/detail/24280/whats‐new‐in‐the‐analysis‐of‐complex‐environmental‐matricesContact:ProfessorGrahamMills,UniversityofPortsmouth,Tel 442392842115,[email protected],UniversityofSunderland,Tel 441915152596,[email protected]

mailto:[email protected]

mailto:[email protected]


Forthcoming meeting

Emerging contaminants in waters and soils – Public health implications When: 5 April 2017

Where: Royal Society of Chemistry, Burlington House, Piccadilly,

London W1J 0BA

This joint mee ng is organised by the RSC’s Water Science Forum, Toxicology Group, and Environ-

mental Chemistry Group.

The one-day seminar will discuss the chemistry of Contaminants of Emerging Concern (emerging

contaminants), which are those that have recently been discovered in soil and water environments

and are considered to be a poten al risk to the environment and/or and human health.

There will also be poster presenta ons with this theme, together with a poster prize.

This is the second joint ECG mee ng on this topic. For details of the previous mee ng please see the

July 2015 edi on of the ECG Bulle n:

h p://www.rsc.org/images/ECG-Bulle n-July-2015-final_tcm18-246976.pdf

For more informa on please contact:

Brian Graham, NHBC, [email protected]

Anexpertanalysestakesawatersampletotestforcontami‐nants.Credit:Shutterstock


The UK, along with other industrialised nations, has a legacy of land contaminated with materials from previous use or naturally occurring sources. Here I outline methodologies for assessing human health risks from volatile organic compounds (VOCs) through indoor inhalation.VOCs are organic compounds with vapour pressures10Pa;organiccompoundswithlowervapourpressure

are referred to as semi‐volatile organic compoundsSVOCs . VOCs can be present on brown ield sites, forexampledue topoor storagepracticesor solvent spills.VOCs may be present in the ground beneath existingbuildingsoronvacantsitesintendedforredevelopment.ExamplesofVOCsincludenon‐chlorinatedhydrocarbonse.g. benzene , chlorinated hydrocarbons e.g.trichloroethene , and nitrogen‐, oxygen‐ and sulphur‐containinghydrocarbons e.g. dimethylsulphide .

Factors in luencing the volatilisation of VOCs into thevapour phase from the subsurface includephysicochemical properties that in luence thepartitioningofthesubstanceintodifferentstates,suchasvapour pressure and air‐water partition coef icientbased on Henry’s Law Constant ; soil and aquiferpropertiessuchasporosity,organiccarboncontentandpermeability; and microorganisms in soil andgroundwater.

Indoor inhalation of vapoursGiventheirhighvapourpressures,VOCshavetendedtobethemaincontaminantsofconcernwhenassessingtherisktohumanhealthviainhalationofvapoursfromsoiland groundwater sources. Elevated indoor vapourconcentrations of a hazardous substance can cause chronicandacutehealtheffects,anodournuisanceand/or a lammable hazard. VOCs migrate through theground via transport mechanisms of advection anddiffusion.Vapoursaccumulatebeneathbuildingsandcanmigrateinsideviacracksinfoundationsand loorslabs.

Assessment methodologiesAnassessmentoftherisktohumanhealthfromvapourintrusion incorporates several considerations, includingsource properties toxicity and physicochemicalparameters of the substance or substances , pathwayproperties site measurements, vapour modellingapproach, soil and aquifer properties, vertical/horizontal distance between source and receptor , andreceptorproperties buildingdesign,resident,worker .UK:Contaminatedlandexposureassessment CLEA The Environment Agency CLEA model 1 has beendeveloped to derive assessment criteria for soilcontaminants. It incorporates multiple exposurepathways,includingtheinhalationofvapours.TheCLEAmodelcanbeusedtoderiveseparateassessmentcriteriafortheinhalationofvapourspathwayonly.An Environment Agency EA review of models forpredicting vapour intrusion into buildings 2 recommended that an approach based on the JohnsonandEttinger J&E screeningmodelshouldbeincludedin the CLEA model 3 . The J & E model uses a one‐dimensional analytical solution to diffusive andadvective transport of vapours and calculates anattenuation factor that relates steady state gasconcentrationsatthesourcetoindoorairconcentrationsbased on soil and building characteristics. It has anumber of simplifying assumptions regardingcontaminant distribution and occurrence, subsurfacecharacteristics, transport mechanisms and buildingconstructionanddesign 3 .TheJ&Emodelisgenerallyrecognised to be over‐conservative in many cases,particularly as it assumes no degradation or sourcereductionovertime.UnitedStates:EnvironmentalProtectionAgency EPA The US EPA has produced technical guidance on thevapour intrusion pathway 4 , including a database ofvapour concentrations recorded at sites in the USA. Ithas developed a tool to derive vapour intrusionscreening levels VISL for groundwater, soil gas andindoorair indefaultexposurescenarios 5 .Thevaluesderived by the VISL tool are based on a generic

ECG Environmental Briefs ECGEB No 14

Volatile organic carbons and vapour

intrusion James Lymer (Wardell Armstrong, [email protected])


conceptual model, which assumes a groundwater orunsaturatedzonesourceofvapoursthatdiffusethroughunsaturatedsoils toward thesurfaceand intobuildings,theoccupiersofwhichare thereceptors. It isassumedthat sub‐surface conditions will reduce or attenuatevapour concentrations as vapours migrate toward thebuilding,and thatdilutionofvapourswilloccuras theymixwithairinthebuilding.The screening levels are used to assist in determiningwhethervolatilesubstancesinthesubsurfaceposearisktohumanhealthviathevapourintrusionpathway.Theyare not intended to be used as clean‐up levels orremediationtargets.Thetoolallowsforthederivationofsitespeci icvalues.

Site measurementsTypically in the UK, soil and groundwater samples areanalysed for VOCs during routine intrusive siteinvestigation works. An initial vapour intrusionassessmentcan thenbecarriedoutbycomparing theseconcentrations with genericassessment criteria GAC . Thisapproach is focussed oncharacterising the VOC sourcearea and is limited by the use ofgeneric screening tools, with nosite‐speci ic conditions such asinclusionofpreferentialpathwaysordegradationofvapours.Site measurements can also betakentosupportamoredetailedassessmentandreduceuncertainty byproviding insight into actual site vapourconditions.Thesemeasurementsmayincludesoilvapoursampling,sub‐slabvapoursampling takenbeneath loorslaborfoundations ,andindoorairmeasurements.Thesetechniquesareintrusiveandcanbeproblematicifthere are occupier concerns and access constraints.Indoor air measurements can be in luenced bybackground VOC concentrations from sources such ascleaning luids,furnishings,andcigarettes.Theanalyticalmethods should be appropriate for comparison withrelevant target concentrations in air. At vacant siteswhere the proposed buildings are not yet in place, sitemeasurementpossibilitiesaremorelimited;forexample,soilvapoursamplesmaynotberepresentativeofvapourconcentrationsunder futurebuildings and sub‐slab andairsamplingisnotpossiblepriortoconstruction.Documents published in 2009 and 2012 present a UK‐based approach to the investigation, monitoring andremediationofVOCsinground 6,7 .

Non-chlorinated and chlorinated hy-drocarbonsVapourintrusioncanbeakeypathwayforhumanhealthexposure from chlorinated and non‐chlorinatedhydrocarbons 8 .Volatilepetroleumhydrocarbonstendto readily biodegrade under aerobic environmentalconditionsifsuf icientoxygenandmicrobesarepresent,whereas volatile chlorinated hydrocarbons tend tobiodegrade much more slowly and prefer anaerobicconditions.

MitigationConventionalremediationtechniquessuchasexcavationand ex situ treatments biological, physical, andchemical may be appropriate to reduce the VOCconcentrations at vacant sites prior to redevelopment.Alternatively, the design of the proposed buildings canincorporatemitigationmeasures such as sealing cracksin foundations, installing vapour membranes,depressurisationandventing.

Mitigating VOC contaminationbeneathexistingbuildingscanbeproblematic and more expensivethan at redevelopment sites.Reasons include likely limitedaccess to the source area,limitations and cost of in situtechniques for removing VOCcontamination beneath thebuilding such as soil vapourextraction and air sparging , and

dif iculties with retro itting a passive membrane to anexistingbuilding. References 1. JamesLymer,ECGBulletinJuly2013,23‐24 2013 .2. EA, Vapour Transfer of Soil Contaminants, R&D

TechnicalReportP5‐018 2002 .3. EA,UpdatedTechnical Background to CLEAModel,

SR3 2009 .4. US EPA, Technical Guide For Assessing And

MitigatingTheVaporIntrusionPathway 2015 .5. USEPA,VaporIntrusionScreeningLevels 2014 , www.epa.gov/vaporintrusion6. CIRIA,TheVOCsHandbook,C682 2009 .7. CIRIA, Remediating and mitigating risks from

volatileorganiccompound VOC vapoursfromlandaffectedbycontamination,C716 2012 .

8. US EPA, Vapor Intrusion: Petroleum HydrocarbonsAnd Chlorinated Hydrocarbons Differ In TheirPotentialForVaporIntrusion 2012 .

An assessment of the risk to human health from va-pour intrusion incorporates several considerations, in-cluding source, pathway, and receptor properties.

http://www.epa.gov/vaporintrusion


The term non-Aqueous Phase Liquids (NAPLs) describes a class of organic liquids that are immiscible with water. NAPLs are among the most common organic contaminants in the sub-surface environment as a result of their ubiquitous use, accidental release during handling or transport, leakage from storage tanks, and poor disposal practices. Thekeyde iningpropertiesofNAPLsaretheirchemicalcomposition,density,wettabilityandinterfacialtension,viscosity, solubility, and vapour pressure. Density isparticularly important, as NAPLs are usually furthercategorised as Light NAPLs LNAPLs , which are lessdensethanwater,anddenseNAPLs DNAPLs ,whicharedenserthanwater.ThemostcommonLNAPLsare fuelsandoils,suchaspetrol gasoline ,diesel,heatingoilsandjet fuel kerosene .TypicalDNAPLs includechlorinatedsolvents,coaltarsandpolychlorinatedbiphenyloils.

Environmental Behaviour WhenanNAPLisintroducedintothesoilenvironmentitnormally migrates downward. The path taken can,however,bequitecomplexanddependson theporeorfracture size of the soil and the concomitant capillaryforcesgeneratedwhentheNAPLcomesintocontactwithwater in the soil’s unsaturated zone and at the watertable. LNAPLs normally cannot penetrate below thewater table because of buoyancy forces, although asuf iciently large LNAPL mass will depress the watertable.DNAPLs,ontheotherhand,canandveryoftendopenetratethewatertable.At the trailing edge of the NAPL body, NAPL dropletstermed residuals and encountered as blobs or gangliastretching through several pore spaces becomedetachedandarenormallyheldintheseporespacesbycapillary forces. This happens both in the unsaturatedand saturated zonesof the sub‐surface environment. In

theunsaturatedzone,vaporisationofNAPLcomponentsproduces a mobile contaminant plume in the vapourphase. Residuals in the unsaturated zone may alsodissolve in in iltrating rainwater, which eventuallyprovidesasourceofgroundwatercontamination. Inthesaturated zone, NAPL residuals slowly dissolve inlowinggroundwatertocreateacontaminantplume.

Capillary Forces TheentryofaNAPL intoanair‐orwater‐ illedporeorfractureisdeterminedbytwoimportantpressureterms.The irstisthecapillarypressure,Pc,whichisde inedbythefollowingequation: Pc Pnw Pw 1 where P represents pressure and the subscripts c, nw,and w refer to capillary, non‐wetting, and wetting,respectively. Awetting luid is one that spreads over asurface in competition with another luid. In soils androcks, water is usually the wetting luid when incompetition with a NAPL. However, when in contactwithair,NAPLsarethewetting luids.Wettingbehaviour ischaracterisedbythecontactangleFigure 1 . The contact angle is the angle made by atangent to the non‐wetting luid and the solid surfaceproceedingfromthepointwherethethreephasescome

ECG Environmental Briefs ECGEB No 15

Non-aqueous phase liquids: proper-

ties, risk reduction and remediation Steve Leharne (University of Greenwich, [email protected])

Figure1.ThecontactangleandporethroatsizeplaykeyrolesinthedynamicsofNAPLsthroughsoils.


intocontact.Thiscontactpointisinrealityacontactlinewhenviewedinthree‐dimensionalspace.Thesecondpressuretermistheentry ordisplacement pressure,Pe,andisgivenbytheLaplaceequation: Pe 2σcos θ /r 2 Hereσ is the interfacial tensionbetweenwaterandtheNAPL, θ is the contact angle, and r is the pore throatradius.Thecontactangletermappearsasacosineterm.Ifθis0°thenthecosinetermis1.Ontheotherhand,acontactangleof90°givesacosineofzero,implyingthata positive entry pressure only arises at a curvedinterface. For the NAPL to displacewater from a pore,thefollowinginequalitymustholdtrue: Pnw Pw 2σcos θ /r 3 Thus, in soil media with large grain size, the entrypressureissmallandNAPLs—especiallyDNAPLs—tendto displace water from pores. On the other hand, inlocationswith small grain sizes NAPLs ind it farmoredif icult to displace water. Thus, if a highly permeablelayer such as sand overlays a less permeable layersuch as silt or clay , NAPLs will migrate verticallydownwardinthetoplayerbutthenmigratehorizontallywhen encountering the bottom layer. Identifying themigrationpathwayofaNAPLthereforerequiresagoodunderstandingofsub‐surfacelithology.

Solubilisation and vaporisation Key concerns after a NAPL spill are its impacts on theenvironment and the resulting liabilities of site ownerswhere the release has occurred. Density and viscositycontrolthelengthoftimeduringwhichaNAPLbodywillremainmobile.Chlorinatedsolventshavehighdensitiesand low viscosities therefore do not remainmobile forlong. In contrast, creosotesandcoal tarshavedensitiesonly slightly greater than that of water and largeviscosities and can therefore continue to migrate forconsiderableperiodsoftime.ThepartialpressureofNAPLcomponentsinthevapourphaseoftheunsaturatedzoneisanimportantriskdriverfor contaminant migration to off‐site targets. In theabsence of a complete understanding of the physicalchemistryofaNAPLmixture,itisgenerallyassumedthatRaoult’s Law gives the partial pressure, pi, of acomponentinthevapourphase:

pi xipisat 4

Here,xiisthemolefractionofcomponentiandpisatisthesaturated vapour pressure of component i. Clearly, low

molecularmasscomponentswithlowboilingpointsareparticularlymobileinthevapourphase.Raoult’s Law is also used to estimate componentsolubilities, using an analogous equation to equation 4wheresreferstothesolubility:

si xisisat 5

Thereadershouldbegintounderstandfromtheforgoingdiscussion that although NAPL releases result in thecreation of a contaminant source zone, it is theappearanceofNAPLcomponentseitherinthevapouroraqueous phase that is usually irst detected and thatprovides the background to environmental riskassessments.

Risk Reduction and Remediation Removal of the source or breaking the pathway can beused to reduce chemicalhazardexposure to acceptablelimits. For LNAPLs like petroleum, vapour phaseextractionisveryofteneffectiveforsourceremoval.Forexample,vacuumenhancedrecoverytechniquesrelyonthevaporisationofvolatileLNAPLcomponentsfromtheorganic liquid phase and volatilisation of componentsfromthewaterphase.Additionally,applicationofahighvacuum to the sub‐surface induces air to enter, whichprovides fresh supplies of oxygen and thereby aids thebiodegradationofthehydrocarboncomponentspresentinthesourcezone.ForchlorinatedhydrocarbonsolventsDNAPLs , some success has been achieved with thejointapplicationofanelectrondonorsystem emulsi iedsoya oil, methanol and lactate and a halo‐respiringbacterium.OtherapproacheshavebeenuseddependingonthelocationandtypeofNAPLspill 1,2 . References 1. B. H. Keuper, G. P. Wealthall, J. W. N. Smith, S. A.

Leharne, D. N. Lerner, An Illustrated Handbook ofDNAPL Transport and Fate in the SubsurfaceEnvironmentAgency,2003 ,availableathttps://clu‐in.org/conf/itrc/dnaplpa/dnapl_handbook_ inal.pdf

2. M.O.Rivett,D.W.Tomlinson,S.F.Thornton,A.O.

Thomas,S.A.Leharne,G.P.Wealthall,AnIllustratedHandbookofLNAPLTransportandFateintheSubsurface CLAIRE,2014 ,availableat

www.claire.co.uk/LNAPL