references regarding the arsenic

1. GR
O
U
N
D
W
A
T
E
R
CONTAMINATION

2. GROUPM
E
M
B
E
R
S
N
A
M
I
T
HAM.R. 2011-02-028
NIDHINJ.K. 2011-02-029
S
A
H
L
AN. 2011-02-030

3. POLLUTION
vs.
C
O
N
T
AMINA
TIO
N
 Pollutionsignifies anydegradationofnatural
groundwater quality while contaminationis
reservedfor pollutionthat constitutesahazard
tohuman health

4. POLLUTIONOFGROUNDW
A
T
E
R
 Defined astheartificially induceddegradation
ofnatural groundwater quality
 Pollutioncanimpair theuseofwater andcan
createhazardstopublichealththroughtoxicity
or thespreadof disease

5.  In contrastwith surfacewater pollution,
subsurfacepollutionisdifficult todetect
andcontrol,andmaypersistsfor
decades.
 Effortsare increasingtoprevent, reduce
andeliminatewater pollution

6. Pollutioninrelationto
wateruse
 Thepossiblepollutantsin groundwater are
virtually limitless
 Thesourcesandcausesofgroundwater
pollutionare closelyassociatedwith humanuse
of water

7.  Groundwater contaminationscenarios :-
a. Point sources :Storagetanks,landfills,
pipeline releasesetc.
b. Nonpointsources:Agriculturalactivities
 Contamination originatesfrom thedisposalof
groundwaterfollowing itsusefor awidevariety of
purposes

9. SOURCESANDCAUSESOF
POLLUTION
 All sourcesandcausesofpollutioncanbeclassified
astotheir geometry
a. Point sources :Originatesfrom asingle location
b. Line sources :Predominantlylineararrangement
c. Diffuse sources:Occupiesanextensivearea

10.  Principalsourcesandcausesofpollutionwith
regard totheir occurrence:-
a. Municipal sourcesand causes
b. Industrial sourcesand causes
c. Agricultural sourcesandcauses
d. Miscellaneoussourcesandcauses

11. 1.Municipalsourcesandcauses
a) Sewerleakage
 Sources:Poorworkmanship,defectivesewer
pipe,breakagebytreeroots,rupturesfrom
heavyloads,earthquakes,lossoffoundation
supportetc.
 Results: Introduce high concentrationsof
BOD,COD,nitrate, organicchemicals,bacteria
andheavymetalsinto groundwater

12. b) Liquidwastes
 Sources:Domesticwastes,Disposalwells
industries,storm,runoff etc.
 Results:Introducebacteria, viruses,trace
elementsandheavymetals,inorganic and
organicchemicals etc.

13. c) Solidwastes
 Sources:Landfills
 Results:
 Leachatefrom landfills canpollute groundwater
 Leachateincludeiron manganese,nitrate, trace
elementsetc.

14. 2. Industrialsourcesandcauses
a) Liquidwastes
 Sources:Industrial wastewater dischargedinto
pits,ponds,lagoons etc.
 Results:Introduction ofhazardousandtoxic
industrial wastesinto thegroundwater

15. b) Tankandpipeline leakage
 Sources: Gasoline stations, fuel oil tanks,
petroleum and petroleum products from
industrial pipelinesand tanks
 Results:Immiscibleliquidslike oil andpetroleum,
liquid radioactivewastesetc.reachesthewater
tableandpollutesthe groundwater

16. c) Mining activities
 Sources:-
 Coal,phosphateanduranium mines
 Stone,sandandgravelquarries
 Results:LowpH, increasein iron, aluminium
andsulphatecontentin the soil

17. d) Oil-field brines
 Sources:-
 Substantialdischargesofwastewaterin the
form of brine
 Constituentsofbrine includesodium,calcium,
ammonia,boron,chloride,tracemetalsand
high total dissolvedsolids
 Results:Groundwaterbecomesaline

18. 3. Agriculturalsourcesandcauses
a) Irrigation ReturnFlows
 Sources:Irrigation return flow drainstosurface
channelsor joinstheunderlying water
 Results:-
 Increasessalinityof groundwater
 Increasestheamountofbicarbonate,sulphate,
chlorides,nitratesetc.in the groundwater

19. b) Animal wastes
 Sources:Wastesfrom slaughterhouses
 Results:-
 Thenatural assimilativecapacityofthe soil
becomeovertaxed
 Salts,organicloadsandbacteriaare transported
into the soil
 Nitrate-nitrogen isthemostimportant persistent
pollutantthat mayreachthewater table

20. c) FertilizersandSoil Amendments
 Sources:
 Leachateofphosphateandpotassium
fertilizers
 Leachateofsoilamendmentslike lime,
gypsumand sulphur
 Results:Increasessalinityofsoil

21. d) Pesticides,insecticidesand herbicides
 Sources:Leachateofpesticides,insecticidesand
herbicidesusedin agriculturalfields
 Results:Causesseriousconsequencesin relation
totheportability of water

22. 4. Miscellaneoussourcesand causes
a) Urbanisation
 Groundwaterpollutioncanoccurbothin rural
aswell asurban areasandisaffectedby
differencesin chemicalcomposition,biological
andchemicalreactions,densityanddistance
from dischargeareas

23. b) SpillsandSurface Discharges
 Causalactivitiesincludesleaksfrom pipesand
valves, uncontrolled wastedisposal,intermittent
dumpingoffluids onground,flushinghazardous
andflammableliquidsinto water etc.
 Washing aircraft with solventsand spills of fuel at
airports can form a layer of hydrocarbons floating
onthewater table.

24. c) Stockpiles
 Solidmaterialsarefrequently stockpiled
near industrial plants,constructionsite etc.
 Precipitationfalling onunshelteredstockpiles
causesleachingofheavymetals,saltsandother
pollutantsinto the groundwater

25. d) Septictanksand Cesspools
 Septictank:Awatertight basinintended
todecomposethedomesticsewageand to
dischargethisinto thebiologicallyactivezone
of thesoilmantlethrough asubsurface
percolationsystem
 Cesspools:large buried chamberwith porouswalls
designedtoreceiveandpercolateraw sewage

26. e) Roadwayde-icing
 Resultsfrom theapplication ofde-icing saltsto
streetsandhighwaysin winter
 Sodiumchloride andcalciumchloride are
generallyused
 Saltreachesthegroundwaterin solutionafter
spreadingonroadwaysandalsofrom stockpiles

27. g) Interchangethrough wells
 Becausewellsform highly permeablevertical
connectionsbetweenaquifers,theycanserveas
avenuesfor groundwaterpollutionwhere
inadequateattentionisgiventotheproper
construction,sealingor abandonmentof wells

28. f) Salinewater intrusion
 Saltwater mayinvadefreshwateraquifersto
createpointor diffusepollution sources
g) Surfacewater
 Pollutedsurfacewater bodiesthat contributeto
groundwaterrechargebecomesourcesof
groundwater pollution

29. Attenuationofpollution
 Pollutantsin groundwatertendtobe
removedor reducedin concentrationwith
time andwith distance travelled
 Therate ofpollutionattenuationdependson
thetypeofpollutantandonthelocalhydro
geologicsituation

30.  Mechanismsinvolved include:-
 Filtration
 Sorption
 Chemical processes
 Microbiological decomposition
 Dilution

31. conclusion
 Theprincipal sourcesandcausesofgroundwater
pollutioncanbecategorized- municipal, industrial,
agricultural andmiscellaneous
 With thegrowingrecognitionoftheimportanceof
undergroundwater resources,effortsare increasing
toprevent,reduceandeliminategroundwater
pollution.

32. T
H
A
N
KY
O
U