In 1945, a booming chemical industry launched a new, effective tool for dealing with insect pests: DDT. It held great promise, including the hope of saving crops and eradicating disease-carrying insects. Twenty years later, DDT and other similar chemicals had indeed benefited agriculture and relieved some of the problems associated with insects in many areas of the world. However, these gains came at a price, as DDT is toxic to many more organisms than those it was intended to kill. In particular, birds of prey had trouble reproducing, and their populations declined in many polluted parts of the world.
As early as 1970, when it was detected in the blubber of ringed seals, it was evident that DDT was present in the Arctic. By the mid-1970s, DDT and other pesticides had been detected in beluga whale, polar bear, and fish. Moreover, birds of prey declined in northern areas that were thought to be uncontaminated.
In addition to pesticides, most tests of animals also found traces of industrial oil made of chemicals known as PCBs. By 1980, there was evidence that these chemicals had reached the Arctic via long-range transport. In the late 1980s, there was evidence that human mother's milk at a location in the Northwest Territories of Canada contained enough PCBs to cause concern about effects on human health. The most likely source was the food the woman had eaten.
Long-range transport via the atmosphere is the most likely source of these persistent organic pollutants in the Arctic. However, efforts to quantify the amount of POPs transported in this way and to determine source regions, are quite limited.
As early as 1970, when it was detected in the blubber of ringed seals, it was evident that DDT was present in the Arctic. By the mid-1970s, DDT and other pesticides had been detected in beluga whale, polar bear, and fish. Moreover, birds of prey declined in northern areas that were thought to be uncontaminated.
In addition to pesticides, most tests of animals also found traces of industrial oil made of chemicals known as PCBs. By 1980, there was evidence that these chemicals had reached the Arctic via long-range transport. In the late 1980s, there was evidence that human mother's milk at a location in the Northwest Territories of Canada contained enough PCBs to cause concern about effects on human health. The most likely source was the food the woman had eaten.
Long-range transport via the atmosphere is the most likely source of these persistent organic pollutants in the Arctic. However, efforts to quantify the amount of POPs transported in this way and to determine source regions, are quite limited.
The article :
http://www.arctic.noaa.gov/essay_calder.html
By:
Wu Jiahao
http://www.arctic.noaa.gov/essay_calder.html
By:
Wu Jiahao