kemi seminal 2(1)

7/26/2019 Kemi Seminal 2(1)

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1.0 INTRODUCTION

Lagoons are shallow brackish bodies of water separated from the ocean by a barriers

island or sand bank and connected at least intermittently to the open ocean by one or

more restricted tidal inlets, found on all continents, usually oriented parallel to the coast,

Lagoon system vary greatly on size from as small as hectare in area to more than

10,000km2 eg Lagoa dos patos, Brazil) ) and north merica !1"#$%), the coast of sia

!1'%) south merica 12#2% ustralia 11#(% and urope !*#&%) +he most etensive

stretch of coastal lagoons is along the atlantics and -ulf coastal united states, where day

cover . 2#'00 km of shoreline however there also common along the eastern coasts of

/outh merica and ndia, /outhern Britain and western rance, the western coast of

frica, and south eastern ustralia as well as along the shores of the Baltic, Black,

aspian and 3editerranean seas, n 4igeria, there are ten lagoons found only in south5

western 4igeria !Lagos) +hey are the 6loge, 7ewa, Badagry, yagbe, 8uramo, 6ni9edi,

Lagos, pe, Lekki and 3ahin lagoons these lagoons run parallel to the -ulf of -uinea

coastline over a distance of about 2&"km# 6ni9edi lagoon is the only closed lagoon in the

region while the 8uramo lagoon is seasonally closed and flows into the sea in the wet

season via the 8uramo ll the other eight, are open lagoons# lagoon may or may not be

sub9ect to tidal miing, and salinity can vary from that of a coastal fresh5water lake to a

hyper saline lagoon, depending on the hydrologic balance# Lagoons formed as a result of

rising sea level mostly during the :olocene and the building of coastal barriers by marine

processes# +hey are often highly productive and ideal systems for a;uaculture pro9ects

but are, at the same time, highly stressed by anthropogenic inputs and human activities#

Lagoons are common in the coastal environment of many islands# +hey are areas of water

with some link to the sea, but sufficiently cut off or protected so that there are special

environmental conditions inside them# +hey therefore present special problems forenvironmental management# +he types of lagoon depends on the form and origin of the

island and often the stage of coral reef development, since it is often coral reefs growing

up to the surface that cut off and protect an area of water, making a lagoon# ven a

fringing reef may have a depression between the reef crest and the shore, forming a

narrow shallow lagoon# barrier reef can be up to several kilometers offshore, creating a

large lagoon which may be tens of meters deep and contain island and patch reefs#

!4wilo, 1


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Figure 1: Lagoon system showing Lagos Lagoon Source: Onyema !00"#

$%ate 1: Image o& the Lagos Lagoon Source: UN'$ 1""(#

+he Lagos Lagoon is a ma9or geographical feature in Lagos, being the largest of the

network of lagoons that stretch from =epublic of Benin through to the 4igerian 4iger

>elta# ?arts of the lagoon waterfront have degenerated into slums, with mainly shanties at

various points, wood preservation, markets and sand dredging activities, robbing the area

of potential urban tourism revenue# -rowing statistics indicate financial gains in

eploiting water tourism# n recognition of this, the Lagos -overnment is pursuing an

aggressive tourism and waterfront development strategy for Lagos 3etropolis# +o


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determine the place of landscape features of the Lagos Lagoon on its viability for

tourism, the research evaluates the lagoon@s landscape characteristics and answers

;uestions of landscape perception of the area !69olowo, 2012)#

Lagos lagoon is a ma9or water body in the Lagos metropolis# t cuts across the southern

part of the metropolis, linking the tlantic 6cean !in the west and south) and Lekki

Lagoon !in the east)# t is about $&*(#"0' s;# km in area and 2'* km in perimeter#

reaA 20's; km

>epth A verage of 1m !ecept for areas that are dredged)

Length A *0km

idthA 1&km

BridgesA +hird mainland bridge, ko bridge, arter bridge

t also provides a good platform for inland waterways transportation which has

potentialities of reducing transportation problems in Lagos metropolis and a place of

abode for the some of the indigenous fishing communities such as the la9es and 9aws

!/tilts housing)# +he Lagos lagoon is one of the four ma9or lagoons in the 4igerian

coastal system, and a significant tourist attraction centre in Lagos /tate# >ue to the level

of primary production in the lagoon, it is usually inhabited periodically by fish species of

fresh water and marine origins, in search of food and good nursery ground !mmanuel,

2010)# t has been reported that about &(% of fishes observed in this ecosystem are of

freshwater origin and the remaining being marine# 3ullets, sardine and bonga

!lupeidae) were classified as permanent fishes in this habitat# +he fisheries productivity

of the Lagos Lagoon system is put above "* kgChaCyear and the fishermen from the

4igerian coastal lagoon and estuaries contribute more than *0% of the current domestic

fish production of about '00,000 metric tons# t was also reported that about 2' metric

tonnesChaCyear of oysters are produced annually from this ecosystem# s a result oflagoon@s rich fauna, especially in fishes, fishing activities are usually witnessed on a daily

basis# =ecently, the state government is proposing using the Lagos Lagoon for cage

culture as a form of contribution to food security and research# ish and fisheries

products are generally regarded as an important part of a healthy diet# n the developing


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ountries, fish and fisheries products apart from being a source of cheap animal protein,

are widely consumed as they have high ;uality protein and other essential nutrients, and

are low in saturated fat while containing 6mega & fatty acids# n 4igeria, most

investigations of the Lagos Lagoon have focused on the sediments and benthic

communities, the diversity and density of macrobenthic fauna in the western part of the

lagoon, trend of heavy metals concentrations are in the Lagos Lagoon, the food and

feeding interrelationships of the fishes and the biology of some fishes and the fisheries#

+here is however, a need to update most of these studies and provide current information

on the diversity of the edible fishery and the effects of pollutants on the health and

abundance of these organisms inhabiting the Lagos Lagoon# By virtue of its position, the

Lagos Lagoon is surrounded by the densely populated !about fifteen million people) and

highly industrialized Lagos metropolis, making it a convenient dumping site for

numerous industrial and domestic wastes, an estimated 10,000 m& of industrial effluents

are discharged into the Lagos Lagoon per day# +hese estimates also confirmed that the

industries are the ma9or source of metal contaminants in the drains, streams and lagoon,

since the graded prominence of metal types was similar in the sampled effluents and

a;uatic systems !delegan, 200()#

+he continued discharge of all sorts of untreated waste materials into the lagoon threatens

the state of ecological e;uilibrium and diversity of fisheries resources in the lagoon, theuse of the lagoon as a dump for waste materials has reduced annual fish production in the

Lagos Lagoon by over five folds between 1


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Lagos Lagoon have focused on the sediments and benthic communities, the diversity and

density of macrobenthic fauna in the western part of the

Lagoon, trend of heavy metals concentrations are in the Lagos Lagoon, the food and

feeding interrelationships of the fishes and the biology of some fishes and the fisheries#

+here is however, a need to update most of these studies and provide current information

on the diversity of the edible fishery and the effects of pollutants on the health and

abundance of these organisms inhabiting the Lagos Lagoon# By virtue of its position, the

Lagos Lagoon is surrounded by the densely populated !about fifteen million people) and

highly industrialized Lagos metropolis, making it a convenient dumping site for

numerous industrial and domestic wastes, an estimated 10,000 m& of industrial effluents

are discharged into the Lagos Lagoon per day# +hese estimates also confirmed that the

industries are the ma9or source of metal contaminants in the drains, streams and lagoon,

since the graded prominence of metal types was similar in the sampled effluents and

a;uatic systems !delegan, 200()# +he Lagos lagoon system is the largest of the four

lagoon systems of the -ulf of -uinea !hukwu, 2002)# +his a;uatic ecosystem is habitat

to a variety of biota which include the plankton, nekton and benthos in a comple trophic

interrelationship !mmanuel and 6nyema, 200")# +he Lagos lagoon ecosystem is habitat

to a variety of biota which include the plankton, nekton and benthos in a comple trophic

interrelationship !mmanuel and 6nyema, 200")#

ccording to by 6nyema !200


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FIN )ND S*'LL FIS*

ommon fin and shellfish in the Lagos lagoon include our species of cichlidae were

identified# +hey are Sarotherodon melanotheron, !emichromis fasicatus and "ilapia

guineensis# 6ther species include larias gariepinus hrysichthys nigrodigitatus

aran$ hippos, %ugil cephalus,Bathygobius soporator, &leotris vitata, Batanga

lebretonis and Gobioides africanus, 'phichthus rufus and Li(a falcipinnis# /ome

common shellfishes were allinectes amnicola, Penaeus notialis, %acrobrachium

vollenhoevenii and%acrobrachium macrobrachion#

+he continued discharge of all sorts of untreated waste materials into the lagoon threatens

the state of ecological e;uilibrium and diversity of fisheries resources in the lagoon, the

use of the lagoon as a dump for waste materials has reduced annual fish production in the

Lagos Lagoon by over five folds between 1


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Lagoons that are open to the sea may have many of the same corals, fish and other sea

life as well as the ocean itself !?edro, 200()# s the conditions in a lagoon get more

variable and more etreme, the number of kinds of things that can live there will get

smaller and smaller, although those things that can live there may get to be more

common# +he life of lagoons may be more productive and abundant than in the sea

outside if there are nutrients that go into it from the land, or if it is able to accumulate

nutrients because it is protected# +he shallow lagoon bottom is often covered with beds of

sea grass or sea weed and reef corals may grow on the lagoon edges and on patch reefs

within it# t may provide important breeding or feeding areas for fish or other animals

outside the lagoon as well# /ome lagoons support fisheries that are very important for the

island# +hey may have bait fish that can be used to fish while some certain lagoons have

important beds of pearl oyster others may have shell fish that are collected locally for

food !Lawal, 200')# f a lagoon becomes too closed, however, there may not be enough

water echange and the lagoon may become stagnant and support much less life# +here

may even be no oygen left on the bottom for animals to live, because the lagoon

environment is often less managed there may be big changes in the kinds of plants and

animals that grow there something may multiply until it seems to be everywhere then it

may die off, to be replaced by something else# +hese changes may follow the season or

they may happen without any apparent reason !6yewo, 200()#

Lagoons like the other parts of the coastal system may go through important changes over

a long period of time the coral reef may grow up and cut them off more and more from

the ocean !Brown, 2012)# +hey may gradually fill up with sediment until they become

part of the land# f the island is sinking, a lagoon may gradually lose its protective barriers

and become part of the ocean shoreline, if the island is rising, the lagoon may be lifted up

until its bottom is dry land, sometimes a natural change may seem sudden, as when a

growing reef finally stops the flow of the ocean water into a lagoon#

astes and run off from the land may also collect in a lagoon and pollute it# /ome islands

have had cholera epidemics spread by the pollution of seafood caught in the lagoon#

Lagoons are particularly vulnerable to the development of towns or cities around their

edge !E4?, 200()#


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Lagoons are epenses of shallow coastal salt water of varying salinity and water volume,

wholly or partially separated from the sea by sand banks or less fre;uently by rocks#

/alinity may vary from brackish water to hypersanility depending on rainfall, evaporation

and through the addition of fresh sea water from storms, temporary flooding of the sea in

winter or tidal echange# n addition, salinity is one of the ma9or factors that determine

the types of plants and animal that lives in a lagoon#

+he characteristics of many lagoons !e#g# low fishing or high retention times, fine

sediments stratification species restricted to lagoons)# n lagoons the low fishing times

means that internal processes !biological and geochemical) will have a significant effect

!?earce, 2012)# Biological processes will include increased phytoplankton growth in

response to nutrient inputs, subse;uent death and retention of the resulting organic

particulate matter and retention of nutrient arising from breakdown of this organic

material# ?articulate nitrogen in the forum of detritus , for eample, from benthic and

floating macrophytes that respond opportunistically to nutrient enrichment, is also likely

to contribute to the internal source of nutrients for subse;uent to take by algae# 6ther

eamples that contribute to a perpetuating state that affect a lagoon include reduction in

benthic pelagic coupling, changes to benthic food webs and the uncoupling on

nitrification identification !6nyema, 200$)# s a conse;uence of the few case studies of

lagoons and observations in similar systems to lagoons in con9unction with the

characteristics of lagoons, it is concluded that many, if not most saline lagoons would

have a low recovery potential from water ;uality impact and eutrophication impacts

within accepted management and planning time frames#

fter a long day in the full sun, lagoon temperatures can rise ;uite high# f the lagoon is

deep enough and the water miing caused by the wind does not reach to the bottom, thena thermocline may develop !E4/6, 200


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+ransportation !boats and canoes are involve in transporting goods and humans from one

part to another)#

ishing activity !fishing operation is purely at artisanal level)#

n ideal centre for education and scientific research#

Lagoons can also create avenues for harbours and ports development s natural

environment of fishing activity is always very high however, fishing operation is purely

at artisanal level#

=ecreational uses of lagoons involve boating in lakes and natural swimming pools mainly

because of their shelter and conse;uent lack of strong wave action#

Lagoons can be considered as models of the larger marine ecosystem#

Lagoons can also create avenue for harbour@s and ports development#

Im+ortance o& Lagoons

1# oastal lagoons have eceptional ecologic, recreational and commercial value

2# +hey provide diverse habitats !open water, submerged a;uatic vegetation, creeks

and fringing wet land)

+hey serve as nursery, feeding and refuge areas for numerous estuaries, marineand terrestrial orgs many marine sp# 6f recreational and commercial imp# /pend at

least a portion of their life cycles in lagoon and ad9oining coastal wetland habitats#

(# side from the value of their fisheries, coastal lagoons are used by humans for

a;uaculture, electric power generation, biotechnology, transportation and shipping

industries in9ect billions of dollarsCnaira into the economies of coastal region

worldwide#

*# Lagoons serve as number of vital physical and chemical functions involving the

trampy and transformation of nutrient and wastes, filtering of contaminant, and

biogeochemical cycling of substance# +hey therefore can strongly influence the

enital ;uality of coastal :2os#

6. Lagoons also protect coastal watershed are buffering the infrastructure from the

damaging effects of storms, floods and erosion.


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6n the aspect of conservation, it is important we manage and conserve biological

diversity and succession in our coastal waters in order to avail ourselves of the capacity

to counteract negative impacts caused by human beings# lot more effort needs to be

made in order to create awareness about the environment# e should learn from

eperiences of the developed world where they are relatively poor in biodiversity because

they have gained their current ;uality of life at the epense of their biodiversity of

neighbouring countries# ?eople should develop positive attitudes and conserving

behaviour towards the natural resources#


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2#0 T,$'S OF L)-OONS

orms and types of Lagoons !Base on lassification)#

89efre !1


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.0 F)CTORS )FF'CTIN- L)-OONS

?ollution is the introduction by man directly or indirectly of substances or energy into the

a;uatic environment resulting in such deleterious effect as to harm living resources,

hazard to human health, hindrance to a;uatic activities including fishing and impairment

for use of water and reduction of amenities# +he ma9or sources of pollution in the lagos

lagoon are land based#!onyema et al#,200&)# :owever, they may be grouped into twomain sources depending on their mode of entry into the water

i# ?oint source !direct discharge)

ii# 4on5point source !diffuse)#

+he point source include the domestic waste, human and solid waste, waste arising from

petroleum related industries, commercial and industrial activities# +he non5point source

includes agricultural runoff containing nutrients and pesticides, urban run5off and soil

erosion# +hese pollutants can be either natural or unnatural substances and can be

grouped into four types depending on their nature and mode of eistence,

i# ?hysical pollutantsA including discarded ob9ects, weeds, silt clay, other sediments

and decaying organic matters#

ii# hemical pollutantsA toic heavy metals such as cadmium, nickel, organic

pollutantH pesticides, phenols#

iii# 3icrobial pollutantsA microorganism resulting from pollution !sewage) of waters

e#g scherichia coli#

iv# =adioactive pollutantsA include radioactive substances such as radium 22$#

Listed below are the ma9or sources of land based pollution

>omestic waste

ndustrial wastes

gricultural runoff

Erban runoff

/olid and human waste

Domestic wastes


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/ewage pollution of surface waters !lagos lagoon) is a common and consistent

occurrence# +he carter bridge end of the lagos harbour served as a disposal site for

untreated domestic sewage in the lagos municipality# or years, the deterioration and

etrophication of the lagos lagoon water have been steadily accelerating which is primarily

due to the etensive pollution by large ;uantities of industrial and domestic sewage

introduced into the water# +he abundance and distribution of faecal bacterial in the lagos

lagoon is influenced by the salinityof the water# Lower counts of # coli were observed at

the southward area of the lagoon which reccieved seawater from the harbour, while

higher counts were recorded in areas which receive freshwater from river ogun# lso

seasonal variations were observed in the distribution of faecal indicator bacterial in lagos

lagoon# :igher counts were observed during the rainy season when the salinity of the

water is low and the lagoon receives runoff from land#

kundayo !1ifferent industries produce different kinds of products and the type of industrial activity

determines the pollutant generated# 6f all the industrial effluents from various industries,

the waste waters from the petroleum related industry and oil spillage constitute a ma9or

land based source of pollution of 4igerian coastal waters# ctivities of crude oil

eploration and eploitation are to a very large etent going on in all parts of the 4iger

delta# 6il spills originate from sources which includeH oil wells, refineries, oil terminals

and 9etties#

6ther sources of oil pollution include petrochemical plants, numerous oil servicingcompanies which pollute the waters with spent oil grease and other chemical mitures

!adhekpukoli, 1


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$%ate 2: Fish /eath associate/ to chemica% +oisoning &rom in/ustria% +o%%ution.

Source: Se%& ac3uire/ !014#


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)gricu%tura% runo&&

+he campaigning for increased food production in 4igeria has resulted in the

establishment of large farms by a number of individual and companies# Large scale

agriculture often involves the use of fertilizers for improved growth of crops and

pesticides for control of pests# +hese fertilizers could be a source of water pollution

especially during rainy seasons when they are washed from farmlands into wetlands#

Lagos has some odour and taste in 3ay, 1


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2.0 )D)$T)TION OF OR-)NIS7 IN L)-OONS


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4.0 $*,SIO6C*'7IC)L $)R)7'T'R OF T*' L)-OONS

?:7/L 4> :3L +6=/ D=+64/ 4 L-664/

$*,SIC)L

+ides

+emperature

urrents and waves

>epth

+ransparency

olour

urrent

C*'7IC)L

/alinity

p:

4utrients

onductivity

>issolved 6ygen


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8.1.1 7)N)-'7'NT )ND STR)T'-I'S ON *O TO I7$RO9'

'N9IRON7'NT)L ST)T' OF L)-OOS

The &o%%owing management strategies are o&ten +ro+ose/ to im+roe theenironmenta% state estuaries an/ coasta% %agoons:

ncrease monitoring and research to identify impacts and to develop remedial actions thatrestore natural environmental conditions#

?ursue open space ac;uisition and smart development in coastal watersheds to protecthabitat# mplement effective restoration efforts to revitalize altered habitat#

ormulate tighter regulations to limit nutrient and chemical contaminant inputs to estuar5ies and lagoons#

stablish more estuarine reserves to minimize anthropogenic impacts, and to provide pro5tected areas for basic and applied research#

mprove the management of estuarine fisheries to preclude ecessive use or overharvestcommercially and recreationally important finfish and shellfish populations#

3onitor, assess, and remediate water ;uality and habitat degradation associated with a;uHculture operations#

ncrease the interactions between scientists, resource managers, and policy makers tensure informed decisions regarding estuaries and coastal lagoons#

>evelop education and outreach programs that inform students and the general public theimportance of maintaining healthy and viable estuarine and lagoonal environments#

Organi;ations an/ 5o/ies such as

ederal nvironmental ?rotection gency !?)

>epartment of ?etroleum =esources !>?=)

4igerian nstitute for 6ceanography and 3arine =esearch !463=)

ll these bodies including -overnment ministries of transportation, works and

agriculture have a key role to play in the protection and conservation of environment#


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(.0 R'F'R'NC'

)/am= $.7. D. >ertness= ). ?. Day= an/ @e/%er ?.>. !00(#. Sa%tmarsh. In: N. 9. C.

$o%unin e/.#=Aquatic ecosystems: Trends and global prospects.

Cam5ri/ge: Cam5ri/ge Uniersity $ress. $+. 14oca Raton= F%ori/a: CRC $ress. . $+.1168!.

>ere= $.R. an/ 7anta6Conroy= 7. !000#. )re we +%anning &or sustaina5%e /ee%o+mentE

)n ea%uation o& 0 com+rehensie +%ans. J. Am. Plan. Assoc.88: $+!16.

>a/si= h. O%i%a/a%i= *. Lou/ii 7. '%ha&a= 7. Cha%i= R. an/ )amiri= ). !010# 'co%ogica%

&actors a&&ecting the /istri5ution o& ;oo+%anton community in the 7)SS)

%agoonSouthern 7orocco#African Journal of environmental science and technology.

9o%211#= $+


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)ag5e F.'.= Osi5ona O.). an/ Otito%ou= ).). !01!#.Diersity o& the e/i5%e &ishes o& the

Lagos

%agoon.Internationa% ourna% o& &isheries an/ a3uacu%ture. 241#: 24642.

)ao= '. ).= Oyewo= '. an/ Unyima/u= ?. $. 1""8#. ) reiew o& the $o%%uton o& Coasta%

aters in Nigeria . NIO7R Tech $a+er.No. 10o%+s.

Inestment Limite/= Lagos= Nigeria. !18++.

>ir/= '. C. F. 1"(!. Changes on 5arriers an/ s+its enc%osing coasta% %agoons.

'ceanologica Acta2464.

>ir/= '. C. F. 1""2. $hysica% setting an/ geomor+ho%ogy o& coasta% %agoons. $+. "6"= In: >.

er&e e/.#= Coastal lagoon processes.)mster/am: '%seier.

*ein; Center= !00!.!uman lin(s to coastal disasters.ashington= D.C.: The *. ?ohn*ein; III Center &or Science= 'conomics an/ the 'nironment.

$h%eger= F. >. 1"8". Some genera% &eatures o& coasta% %agoons. $+. 46!8= In: ).

)ya%a6Castaneres e/.#= agunas costeras" unsimposio= Uniersi/a/

Naciona% )utonoma /e 7eHico= 7eHico= DF.


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O/iete= .O.= Nwaooro. R.C. an/ )/aramo%a= T. !00#. >io%ogica% assessment o& &our

water courses in Lagos metro+o%is receiing in/ustria% an/ /omestic waste

/ischarges.Journal of #igerian Environment Society.11#: 1612.

OUTLIN'

1.0 INTRODUCTION

De&inition o& %agoons

Im+ortance o& %agoons

!.0 T,$'S )ND FOR7 OF L)-OONS >ase on c%assi&ication#

.0 F)CTORS )FF'CTIN- L)-OON

2.0 )D)$T)TION OF LIF' IN L)-OONS

4.0 $*,SIO6C*'7IC)L $)R)7'T'R OF T*' L)-OONS

8.0 7)N)-'7'NT )ND STR)T'-I'S ON *O TO I7$RO9'

'N9IRON7'NT)L ST)T' OF L)-OONSS


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kemi seminal 2(1)

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