Trong lưu vực nông nghiệp, số lượng lớn các chất dinh dưỡng thường ngấm từ trồng các lĩnh vực. Tăng ứng dụng phân bón thương mại đã dẫn đến cao nồng độ của contaminators. Trong số contaminators nước, nồng độ nitrat và thuốc trừ sâu thường xuyên nhất để phân tích kể từ khi sự hiện diện của các thành phần này trong các nguồn cung cấp nước cấu thành một mối đe dọa trực tiếp đến sức khỏe con người. Nghiên cứu lâu dài về sinh thái cảnh quan được thực hiện bởi Trung tâm nghiên cứu Nông nghiệp và Môi trường rừng ở. | CHAPTER 7 Dissolved Organic Substances in Water Bodies of Agricultural Landscapes Barbara Szpakowska CONTENTS Introduction Terminology and Methodology Source and Origin of Dissolved Organic Substances Concentrations of Dissolved Organic Substances in Waters Humic Substances in Aquatic Environments Amounts of Humic Substances in Ground Waters Amounts of Humic Substances in Surface Waters Concentration of Polysaccharides and Polypeptides in Water Effect of Meadow Width on Humic Substances Concentration in Dry Years Effect of Meadow Width on Organic Substances Concentration in Wet Years Effect of Humic Substances on Heavy Metals Speciation Total Concentration of Heavy Metals in Natural Waters Concentration of Different Forms of Metals Association of Metal Ions with Humic Substances in Natural Water The Effect of Meadow Belt on Heavy Metal Speciation Conclusion References INTRODUCTION In agricultural watersheds large amounts of nutrients are usually leached from cultivated fields. Increased application of commercial fertilizer has resulted in elevated concentrations of contaminators. Among water contaminators concentrations 2002 by CRC Press LLC of nitrates and pesticides are most frequently subjected to analysis since the presence of these components in water supplies constitutes a direct threat to human health. Long-term studies on landscape ecology carried out by the Research Centre for Agricultural and Forest Environment in Poznan have indicated that the spatial pattern of landscape elements can modify migration of mineral components. By restructuring uniform field landscapes into mosaic ones through installing biogeochemical barriers such as shelterbelts meadows small ponds and other nonagricultural components it is possible to decrease the output of phosphates and nitrates from a watershed Ryszkowski 1994 Ryszkowski et al. 1997 . On the other hand there is little data on the leaching and migration of dissolved organic matter DOM in waters situated in agricultural
