which is the worst type of pollution?
24 Nov 08
They are all bad, but to my mind one of the worst is agricultural pollution from fertiliser and insecticide run-off. Quite apart from the fact that the chemical insecticides create immunity in pests, the run-off from both kills river and other marine environment. Then there is the problem of bio-magnification: for example, DDT has become part of the food chain, and biomagnifies the further down the chain it goes, to the extent of appearing now in nursing mothers’ milk, as well as in many other species. This biomagnification was unpredictable, but means that levels of thousands of times the original expected level are being found in nature. I did the fieldwork element of my PhD with commercial fishermen in a fishery considered by every agency concerned as "the jewel in the crown" of Australian fisheries. It was a very small operation, about 15 two-man boats in a quite large inlet using seine-net fishing methods which are extremely efficient in allowing undersize fish to escape and causing the minimum of by-catch problems. But the fishery has shrunk in recent years because the habitat, primarily the sea-grass that feeds the money-fish, the King George Whiting, was dying out. The main reason for this seemed to be agricultural run-off, not so much because it poisoned anything, but because it was too rich in nutrient. A naturally occurring microbe, Pfiesteria piscicida, which is normally benign but which in four of its 24 stages of development is highly toxic, has created havoc in continental USA waterways. The toxicity is apparently triggered by the combination of high nutrients in the water, and large schools of fish. Under specific conditions, such as high nutrient levels and the presence of large schools of fish, Pfiesteria’s population increases. This is referred to as a “bloom.” During a bloom, this organism changes into a free swimming form that may produce toxin(s) which numbs fish and enables Pfiesteria to feed on fish. High levels of toxic Pfiesteria can cause deep, ulcerative lesions on fish, and/or may kill fish. Humans have suffered as well, since the toxins can cause skin irritation; memory loss and other cognitive impairments; nausea and vomiting; and respiratory, kidney, liver, vision, and immune system problems, and it appears that many of these symptoms are both extremely serious and irreversible, and a number of commercial fishermen have been affected. In North Carolina and Maryland, scientists suspect - but have not yet confirmed - that the explosion of Pfiesteria and its toxic relatives is linked to unprecedented amounts of runoff of farm fertilizers and manure. So, the agricultural pollution carries over into so many other areas of our lives, through the food we eat. Lash
24 Nov 08
I agree that agriculture has a lot to answer for. All of these chemicals are leaching out into our water ways and getting eventually to the sea. I do not know the ins and outs like you obviously do but I think it is pretty obvious that this is a bad situation. I know in the UK pregnant women are being recommended to cut their fish eating down and to stay away from shell fish all together. This is not good as years ago when I had my children it was thought that fish was the best food for pregnant women along with plenty of fruit and vegetables. Now you wonder about the vegatables too. I always try to buy organic veg myself but I eat a lot of fish. Maybe that is why my brain powere is slowing down or maybe it is just old age!!
24 Nov 08
I could not choose, they are all bad and they all destroy our world but I am scared of the toxic waste that is going around the world on rusty ships and I dread that one day they will sink and our oceans will be totally destroyed. I cannot understand that no one has done anything to solve this problem. It is like the sword of Damocles hanging over our heads and one day it will fall and when does we are doomed..