水污染(Water Pollution)

详细内容

'

waterpollutioniscausedbywastefromfactoriesandcities.oceansareabletocleanthemselves,butcertainseas,oncetheybeedirty,arenotabletodoso.oneexampleisthemediterraneanwhichliesbetweeneuropeandafrica.ithasonlyeonenarrowentrancetotheoceaninthewest.

onquarteroftheshoresofthemediterraneanarepollutedandarenolongersafeforswimming,asalotofdiseasesarepresentinthewater.inmostplacesitisnotsafetoeatthefish.

lakesalsohavethesameproblems.lakebaikalinasiawasoncethecleanestintheworld,withover700differentkindsofplantandanimallife.now,however,thewatersofthisgreatlake,whichisalsotheworld＇sdeepest(over1,740metres),havebeendirtiedbywastefromachemicalfactory.

in1989anoiltankerhitarockoffthenorthwestcoastofalaska.35,000tonsofoilpouredintothesea.theaidentwasoneoftheworstinhistory.morethan34,000birdsand10,000animalswerekilled.4,800squarekilometresofoceanwerepolluted.