Discuss the causes, effects and control measures for water pollution.

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Causes  of  water  pollution  are  varied:  industrial  effluents;  have  heavy  metals  that  poison  aquatic organisms;  untreated  organic  matter  has  phosphates/sulphates/nitrates/salts;  that  cause eutrophication;  causing  algal  bloom  that  deprives  the  water  of  nutrients;  when  the  algae  die, they  lead  to  an  increase  in  putrefying  bacteria  whose  decomposition  activities  lead  to  the release  of  awful  smells/odours;  oil  effluents  clog  respiratory  surfaces  of  aquatic organisms/death  due  to  suffocation;  domestic  effluents/sewage;  form  a  habitat  of  pathogens that  spread  water  borne  diseases;  decomposing  sewage  promotes  eutrophication  leading  to algal  bloom;  death  promotes/attracts  saprophytic  bacteria  that  use  up  oxygen  in  water;  causing suffocation/death  to  aquatic  organisms;  agrochemicals/fertilizers;  phosphates/nitrates;  cause eutrophication;  heavy  metals  in  agrochemicals  (herbicides/pesticides);  affect  respiratory surfaces/cause  breathing  problems;  Hot  water;  raise  temperature  of  water;  killing  organisms; dissolves  less  oxygen;   reducing  its  content  in  water;  Oil  spillage;  in  oceans  from tanks/refineries;  soak  feathers  of  marine  birds  preventing  flight;  clogs  respiratory  surfaces leading  to  death;  coats  photosynthetic  phytoplanktons;  reduces  light  penetration  hampering photosynthesis;  Sediments;  from  soil  erosion  makes  water  dirty;  making  it  unfit  for consumption;  clogs  respiratory  surfaces  hindering  gaseous  exchange;  reduces  light  penetration hindering  photosynthesis;  Control  methods:  Enforcement  of  environmental  laws;  Use  of unleaded  fuel/petroleum  products;  Proper  treatment  and  disposal  of  sewage  wastes;  Treatment of  industrial  effluents  before  release;  Public  education  on  correct  use  of  inorganic  fertilizers and  agrochemicals;  and  use  of  alternatives  such  as  biological  control  of  weeds/pests/organic manure;  Use  of  undersea  pipelines  instead  of  tankers  to  transport  oil  products;  Cooling  hot water  before  release  to  water  bodies;  Max.  20  mks 

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