Chemical pollution is when fluids, often toxic, get released into the water. Chemicals can find their way into the sea in many ways and come from all sorts of places. Lets take a look -
Industry - Sometimes factories and industry will allow waste products to flow into streams and rivers which eventually get to the sea. Sometimes chemicals are dumped at sea. Chemicals are used in millions of processes whether it is making food, plastic toys, CDs building materials, gadgets or electricals. Through rivers and streams some pollutants enter marine food chains, building up their concentrations until they reach toxic levels.
It often takes human casualties to alert us to pollution and such was the case in Minimata Bay in Japan when many people died as a result of a pollutant building up in food chains. A factory was discharging waste containing methyl mercury in low concentrations into the sea and as this pollutant passed through food chains it became more concentrated in the tissues of marine organisms until it reached toxic levels. As a consequence over a thousand people died from eating fish and shellfish contaminated with mercury and around two thousand people suffered from mercury poisoning.
Farming - Pesticides and herbicides are chemicals sprayed onto food crops to control insects and weeds. These chemicals are often toxic as they are designed to kill or repel animals and contain some synthetic (man-made) chemicals. When sprayed onto crops these substances get left in the soil and can easily find their way into freshwater streams and rivers and end up in the sea. Once in the sea these chemicals often do not disappear by biodegrading as they are resistant to natural breakdown processes but stay in the sea and enter the food chain.
Medicine - Sometimes medicines that humans and animals take also contain bad chemicals and these make their way into the sea through our toilets, into sewage treatment plants and then out into rivers into the sea. For us these chemicals are tolerable in small doses but in aquatic environments they can build up and cause fertility problems in fish.
At home - In our homes we use many different sorts of cleaning, washing and polishing products which all contain various chemicals which often end up down the drain when washed out of dishclothes or used in the bath or kitchen sink. These chemicals may be harmful to wildlife and marine environments as they can contain harmful substances such as sodium hypochlorite, petroleum distillates, phenol and cresol, ammonia and formaldehyde. Buying cleaning products that contain natural soluble/biodegradable ingredients helps to prevent these nasty fluids from ending up in natural water sources. To find out how our washing machines contribute to sea pollution see the Plastic pollution section below. See How to Clean Up our Water for twelve handy tips from the Natural Resources Defense Council.
There are concerns about exactly how these chemicals, that are now mixing together in rivers and oceans, are affecting marine environments and little is known about the effect this may have in humans.
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