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Pesticides in Stream Sediment and Aquatic Biota Distribution, Trends, And Governing Factors - Chapter 7

Cuốn sách này đánh giá hơn 400 nghiên cứu về thuốc trừ sâu trong trầm tích giường và sinh vật thủy sản của Hoa Kỳ sông tiến hành trong ba thập kỷ qua. Xem xét cùng nhau, các tài liệu hiện có cung cấp một cơ sở để đánh giá một phần ít nhất là về mức độ ô nhiễm thuốc trừ sâu của các dòng sông và cửa sông tại Hoa Kỳ, mặc dù có những lĩnh vực mà sự hiểu biết hiện tại của chúng tôi là không đầy đủ. Phần lớn các nghiên cứu xem xét giám. | CHAPTER 7 Summary and Conclusions This book reviews more than 400 studies of pesticides in bed sediment and aquatic biota of United States rivers conducted over the last three decades. Considered together the existing literature provides a basis for at least partial assessment of the extent of pesticide contamination of rivers and estuaries in the United States although there are areas where our current understanding is incomplete. The majority of studies reviewed were monitoring studies ranging in scale from local to national. There was little consistency among the studies reviewed in terms of site selection strategy sample collection methods species of organisms sampled tissue type analyzed and analytical detection limits. In contrast there was great consistency in the types of pesticides that were target analytes in bed sediment and aquatic biota studies the vast majority of studies focused on organochlorine insecticides. Since the 1960s there has been a decrease in processtype studies or field experiments designed to assess the general environmental fate and persistence of individual pesticides and an increase in monitoring-type studies that focused on analytes known to be present in bed sediment and aquatic biota as the environmental fate of hydrophobic pesticides became more generally understood . Results of the hundreds of state and local monitoring studies are difficult to compare because of the large variability in study design which includes factors such as site selection sampling methods and analytical detection limits . However several national programs have been conducted that constitute individual data sets large enough to provide a nationwide perspective on pesticide occurrence and distribution. Together these national monitoring studies have provided good geographic coverage of pesticides in bed sediment and aquatic biota of United States rivers and estuaries. Temporally the national studies have provided the fewest data for freshwater sediment .