river pollution pollution is an addition to the environment with consequent adverse effects to that...
TRANSCRIPT
River PollutionPollution is an addition to the
environment with consequent adverse effects to that environment
The main causes of pollution in rivers are:• Agricultural Pollution - the effects of excess fertilisers and
pesticides and farm slurry• Industrial Pollution - inorganic and organic waste that directly
contaminates rivers• Dumps - spoil heaps and refuse tips release harmful chemicals
that may leach into rivers• Domestic Pollution - treated effluent from sewage works is
discharged into many of our rivers• Thermal Pollution - warm waste water from cooling towers
and other industrial processes raises the temperature of the water and lowers oxygen solubility
• Atmospheric Pollution - pollution of the atmosphere with nitrogen and sulphur oxides produces acid rain that modifies the pH of rivers which, in certain conditions, has lethal effects on the river organisms
• Oil Pollution - can result from river traffic
Water tumbling downa hillside from its source
is crystal clear and unpolluted
As rivers flow through towns, agricultural land and industrial areas, various pollutants enter the water
body and influence the distribution andcomposition of aquatic life
As pollution loads increase, species diversity declines and the abundance of pollution-tolerant species increases
This river is becoming increasingly polluted as organic and inorganic materials ‘run off’ from the surrounding agricultural land
Thermal Pollutionfrom cooling towers
IndustrialWaste
FarmyardWaste
Effluent fromsewage works
Fertiliserrun off
Acid Rain
Oil Pollution
Measuring River Pollution
Methods for detecting and measuring river pollution include:
• Sampling the populations of river invertebrates; river invertebrates are indicator organisms that serve as indicators of the state of the river by their presence or absence
• Chemical testing to determine the amount of dissolved oxygen in the water
• Chemical testing for determining levels of specific chemicals such as ammonia, nitrates and phosphates
• Physical testing such as measurements of the turbidity of the water and the quantity of suspended solids
The amount of dissolved oxygen in the water is a major determinant for the presence and abundance of
invertebrates in river ecosystemsThe discharge of organic material into rivers lowers the oxygen
availability and sensitive organisms are unable to survive
PlecopteraStonefly nymphs
EphemeropteraMayfly nymphs
These invertebrates areintolerant of pollution
and low oxygen concentrations; they feed
on detritus and otherinvertebrates and have
flattened bodies and clawsfor crawling over the
surface of stones
Mayfly and stonefly nymphs are clean water fauna and
indicators of well-oxygenated unpolluted water
TrichopteraCaddis-fly larva
Gammarus pulexFreshwater Shrimp
These invertebrates are tolerant of mild pollution and reappear in rivers polluted with organic material as
oxygen levels return to normal
Asellus aquaticuswater hog-louse
LimnaeaFreshwater Snail
HirudineaFreshwater Leech
These invertebrates are tolerant of moderate pollution and reappear downstream from the polluting source
AnnelidaTubificid worms
in cases
Eristalis teneaxLarva of bee-fly
(rat-tailed maggot)
Chironomus thummiBloodworm – midge larva
These invertebrates are tolerant of high pollution and are adapted to survive the low oxygen levels in polluted water
Tubificid and Chironomus larvae possess a form of haemoglobin in their blood that exhibits a high affinity for oxygen
Rat-tailed maggots possess a breathing tube at their rear end which penetrates the river surface enabling these organisms to obtain
oxygen from the atmosphere
Clean water organismsintolerant of pollution
Organisms tolerant of mild pollution that reappear as rivers recover from organic pollution
Organisms tolerant of mild pollution that reappear as rivers recover from organic pollution
The bright-red colour of Chironomus is due to the presence of haemoglobin,
adapting this organism for survival in conditions of low oxygen concentration
Clean water faunaFauna tolerantof high
pollution
Fauna tolerantof moderate
pollution
Fauna tolerant of slight pollution Fresh water fauna return
The Effectof Organic
Pollution onRiver Fauna
• http://www.youtube.com/watch?v=UGqZsSuG7ao
• http://www.youtube.com/watch?v=h-zncNp-X-E (song)
Dissolvedoxygen
Ammonium ions
(NH4+)
Nitrates(NO3)
Suspended solidsBiologicalOxygenDemand(BOD)C
on
ce
ntr
ati
on
(A
rbit
rary
Un
its)
SEWAGE
DISTANCE DOW NSTREAM
The Effect of Raw Sewage on the Chemical Compositionof a River Ecosystem
Explain the graph
Dissolvedoxygen
Ammonium ions(NH4
+)
Nitrates(NO3)
Suspended solids
Co
nc
en
tra
tio
n (
Arb
itra
ry U
nit
s)
SEWAGE
DISTANCE DOW NSTREAM
BiochemicalOxygenDemand(BOD)
Entry of sewage intothe river increases the quantity of suspended
solids, and light availability to oxygen-
producing aquatic plants is reduced
Organic material in the discharge
provides an abundant source of food for bacteria and other
decomposers resulting in a rapid growth of their populationsThe oxygen level falls dramatically as it is utilised
by decomposers for respiration and the BOD is highThe Biochemical Oxygen Demand reflects the demand for oxygen by the decomposers; it is a measure of the
dissolved oxygen taken up by microorganisms in decaying the available organic matter
Ammonium ions are released as decomposers oxidise the organic matter and these are rapidly oxidised to
nitrates by nitrifying bacteria
Nitrates stimulatethe growth of algae
Organic material is gradually broken
down and the river recovers from the
polluting effects as it flows
downstream
River invertebrates are indicators of the degree of pollution in the river
Species diversity decreases with high pollution and graduallyincreases again as the river recovers
The increased nitrate levels, resulting from
microbial decomposition of organic material,
stimulates the growth of algae
Pollution from Nitrogen Fertilisers
• Nitrogen based fertilisers have many benefits such as increased productivity in plants/crops but they have had detrimental effects:
• Reduced species diversity – grass/nettles prefer nitrogen rich soil, so they out compete other species e.g. silage fields
• Leaching – Rain water removes nitrates from soil and then into streams/rivers. This can be harmful if water is a source of drinking water. High nitrate levels can lead to inefficient oxygen transport in babies and stomach cancer.
• Eutrophication – Fertilisers leaching into watercourses.
Eutrophication• Eutrophication is a natural process but can be made worse by over use of
fertilisers (usually inorganic).• In most lakes and rivers, nitrates exist in low amounts and are limiting factor
for plant and algal growth• Over use of fertiliser on agricultural land near watercourses can lead to
leaching of nitrates into lakes and rivers, leading to nitrate levels increasing.• Algal and plant growth increases exponentially. Algal growth is mainly on
surface and upper layers – leads to ‘algal bloom’• This dense layer absorbs most sunlight and prevents it from penetrating lower
layers. Light is now limiting factor for lower plant life – starts to die.• Dead plants and algae provide food for saprobiotic bacteria, so their
population number grows exponentially.• These decomposers require more oxygen for respiration, so the concentration
of oxygen decreases but nitrates increase due to decomposition.• Oxygen levels are now limiting factor for population of aerobic organisms
(fish, invertebrates) and these die off.• Less competition for anaerobic organisms. These continue to grow in
numbers.• Dead material is further broken down releasing more nitrates and toxic waste
such as Hydrogen Sulphide – Water becomes putrid.
• Complete troubled waters activity
Biotic DataBiotic data was used to calculate the
Simpson’s Diversity Index and the Trent Biotic Index for each site
The Biotic Index is given as a Roman Numeral which describes the quality of the stream, from 0 for
very polluted, to X for very clean
The index is dependent upon the presence or absence of certain indicator species, as well as the
composition of the community
Instructions for determining the index are provided in the workbook
TRENT BIOTIC INDEXAfter F Woodiwiss, Trent River Authority
0-1 2-5 6-10 11-15 16+
-0 I II -
VI
I II III IV -
II III IV V
VII
III IV V VI VII
IV IV V VI
VIII
- V VI VII VIII
- V VI VII
IX
- VI VII VIII IX
- VI VII VIII
Composition Score
- VII VIII IX XHow many species of Plecoptera
(stoneflies) in sample?
How many species of Ephemeroptera (mayflies)
excluding Baetis rhodani (olive mayfly larvae)?
How many species of Trichoptera (caddis flies) (include B.rhodani
here if present)?
Were Gammarus (freshwater shrimps) present in sample?
Were Asellus (water hog lice) present?
Were Tubifex worms and/or red chironomid larvae (bloodworms)
present?
All above animals absent. Were any macro invertebrates present?
Biotic Index 0.Very polluted
START
None
None
No
No
No
No
No
The Biotic Index is given as a Roman Numeral which describes the quality of the stream, from 0 for very polluted, to X for very clean. The index is dependent on the presence or absence of certain indicator species, as well as the composition of the community.
To work out the Index from the table on the right you need to add up a Community Composition Score , and then work through the flow chart. The intersection of the appropriate flow box row and column gives the Biotic Index for the site.
Community Composition Score : You score points for taxonomic groups of animals which are relatively easy to identify. Score one point for each of the following in the sample.
Each species of Platyhelminthes (flatworms)The phylum Annelida (true worms and leeches)Each species of Hirudinae (leeches)Each species of Mollusca (snails etc)Each species of Crustacea (water louse, shrimps) excluding the Cladocera (water fleas)Each species of Plecoptera (stoneflies)Each species of Ephemeroptera (mayflies)Each family of Trichoptera (caddis flies)Each species of Neuroptera (alderflies)The family Chironomidae (midge larvae) excepting Chironomus thummi (bloodworms)Chironomus thummi if presentThe family Simulidae (black flies)Each other species of Diptera (true flies), eg crane fliesEach species of Coleoptera (beetles and beetle larvae)Each species of Hydracarine (water mites)
More than one
More than one
More than one
One
One
One
Yes
Yes
Yes
Yes
Trent Biotic index (After F. Woodiwiss, Trent River Authority