tailieunhanh - PESTICIDES IN AGRICULTURE AND THE ENVIRONMENT - CHAPTER 5

Đánh giá việc vận chuyển và số phận của thuốc bảo vệ thực vật trong môi trường phức tạp. Có vô số các đường giao thông và số phận tại các cấp địa phương, khu vực và toàn cầu. Thuốc trừ sâu tự đại diện cho một nhóm đa dạng các loại hóa chất rộng rãi các đặc tính khác nhau và các mô hình sử dụng. Và môi trường, tất nhiên, đa dạng trong trang điểm và luôn thay đổi, từ một địa điểm khác và từ một trong những thời gian khác. Khoa học môi trường đã phát. | 5 Environmental Fate of Pesticides James N. Seiber Western Regional Research Center Agricultural Research Service . Department of Agriculture Albany California . 1 RATIONALE Assessing the transport and fate of pesticides in the environment is complicated. There are a myriad of transport and fate pathways at the local regional and global levels. Pesticides themselves represent a diverse group of chemicals of widely varying properties and use patterns. And the environment is of course diverse in makeup and ever-changing from one location to another and from one time to another. Environmental sciences have evolved as a means of understanding and dealing with the complexities in nature by sorting out and defining underlying principles. These can serve as starting points or steps in the assessment of chemical processing important to the health of the environment humans and wildlife. In the past particularly from roughly the 1940s to 1970 knowledge of how pesticides and other chemicals behaved in the environment was obtained by retrospective analysis for these chemicals after they had been used for many years. By analyzing soil water sediment air plants and animals environmental scientists were able to piece together profiles of behavior. Dibromochloropropane DBCP ethylene dibromide EDB and chemicals with similar uses as soil ne maticides and similar properties came to be recognized as threats to groundwater in general use areas. DDT and other chlorinated insecticides and organic compounds of similar low polarity low water solubility and exceptional stability threatened some aquatic and terrestrial animals because of their potential for undergoing bioaccumulation and their chronic toxicities. The chlorofluorocarbons CFCs and methyl bromide were found to be exceptionally stable in the atmosphere and able to diffuse to the stratosphere where they entered into reactions that result in destruction of the ozone layer. But as large a testimony as these examples and .