tailieunhanh - RESTORATION AND MANAGEMENT OF LAKES AND RESERVOIRS - CHAPTER 16

Thuốc diệt cỏ thuốc trừ sâu hóa học được sử dụng để quản lý thực vật. Thuốc diệt cỏ cây trồng chết hay bị gián đoạn quá trình phát triển bình thường của họ. Một công thức thuốc diệt cỏ bao gồm một thành phần hoạt động, tàu sân trơ, và có lẽ một số hóa chất khác, chẳng hạn như tá dược làm cho thuốc diệt cỏ hiệu quả hơn. "Hôm nay của dụng cụ (thuốc diệt cỏ) hiện đại phấn đấu để chọn lọc điều trị các loài ngoại lai khuyến khích các loài bản địa tái lập,. | 1 6 Chemical Controls INTRODUCTION Herbicides are chemical pesticides used for plant management. Herbicides kill plants or severely interrupt their normal growth processes. An herbicide formulation consists of an active ingredient an inert carrier and possibly other chemicals such as adjuvants that make the herbicide more effective. Today s modern herbicide applicator strives to selectively treat exotic species encouraging native species re-establishment and to treat other excessive vegetation in more direct use areas leaving less-utilized areas of native species as nutrient and habitat buffers in the ecosystem. This quote by Kannenberg 1997 suggests that the role of herbicides in lake and reservoir management is threefold 1 eradicate exotic species 2 change plant community composition and 3 treat excessive vegetation growth in direct or high-use areas. The decision to use herbicides should be based on the same criteria efficacy cost health safety and environmental impacts regulatory appropriateness and public acceptability- that are used for other management techniques Chapter 11 . This was not always the case. Because herbicide and other pesticide treatments were fast relatively cheap and many times very effective they were used in inappropriate ways regarding health safety and environmental impacts. This influenced public perception about the acceptability of using pesticides. One of the more striking historical cases of overuse of a toxic but very effective aquatic herbicide was the use of sodium arsenite. Between 1950 when the Wisconsin Department of Natural Resources began keeping records and 1970 when it was no longer used approximately 798 799 kg of sodium arsenite were added to 167 lakes Lueschow 1972 . The environmental impacts of these treatments were not monitored. However the use of sodium arsenite causes long-term problems for further management in some lakes where it was heavily used. The sediments in these lakes are a hazardous waste so other .