Zablotowicz Robert M, Locke Martin A, Krutz L Jason, Lerch Robert N, Lizotte Richard E, Knight Scott S, Gordon R Earl, Steinriede R Wade
USDA Agricultural Research Service, Southern Weed Science Research Unit, Stoneville, MS 38776, USA.
Sci Total Environ. 2006 Nov 1;370(2-3):552-60. doi: 10.1016/j.scitotenv.2006.08.023. Epub 2006 Sep 26.
The Mississippi Delta Management Systems Evaluation Area (MD-MSEA) project was established in 1994 in three small watersheds (202 to 1,497 ha) that drain into oxbow lakes (Beasley, Deep Hollow, and Thighman). The primary research objective was to assess the implications of management practices on water quality. Monthly monitoring of herbicide concentrations in lake water was conducted from 2000 to 2003. Water samples were analyzed for atrazine, cyanazine, fluometuron, metolachlor, and atrazine metabolites. Herbicide concentrations observed in the lake water reflected cropping systems of the watershed, e.g., atrazine and metolachlor concentrations were associated with the level of corn and sorghum production, whereas cyanazine and fluometuron was associated with the level of glyphosate-sensitive cotton production. The dynamics of herbicide appearance and dissipation in lake samples were strongly influenced by herbicide use, lake hydrology, rainfall pattern, and land management practices. The highest maximum concentrations of atrazine (7.1 to 23.4 microg L(-1)) and metolachlor (0.7 to 14.9 microg L(-1)) were observed in Thighman Lake where significant quantities of corn were grown. Introduction of s-metolachlor and use of glyphosate-resistant cotton coincided with reduced concentration of metolachlor in lake water. Cyanazine was observed in two lakes with the highest levels (1.6 to 5.5 microg L(-1)) in 2000 and lower concentrations in 2001 and 2002 (<0.4 microg L(-1)). Reduced concentrations of fluometuron in Beasley Lake were associated with greater use of glyphosate-resistant cotton and correspondingly less need for soil-applied fluometuron herbicide. In contrast, increased levels of fluometuron were observed in lake water after Deep Hollow was converted from conservation tillage to conventional tillage, presumably due to greater runoff associated with conventional tillage. These studies indicate that herbicide concentrations observed in these three watersheds were related to crop and soil management practices.
密西西比三角洲管理系统评估区（MD-MSEA）项目于1994年在三个流入牛轭湖（比斯利湖、深谷湖和蒂曼湖）的小流域（202至1497公顷）设立。主要研究目标是评估管理措施对水质的影响。2000年至2003年对湖水中除草剂浓度进行了每月监测。对水样分析了莠去津、氰草津、伏草隆、异丙甲草胺及莠去津代谢物。湖水中观察到的除草剂浓度反映了流域的种植系统，例如，莠去津和异丙甲草胺浓度与玉米和高粱产量水平相关，而氰草津和伏草隆与草甘膦敏感型棉花产量水平相关。湖水中除草剂出现和消散的动态受到除草剂使用、湖泊水文、降雨模式和土地管理措施的强烈影响。在种植大量玉米的蒂曼湖观察到莠去津（7.1至23.4微克/升）和异丙甲草胺（0.7至14.9微克/升）的最高最大浓度。精异丙甲草胺的引入和抗草甘膦棉花的使用与湖水中异丙甲草胺浓度降低同时出现。在2000年，在两个湖泊中观察到氰草津，其含量最高（1.6至5.5微克/升），而在2001年和2002年浓度较低（<0.4微克/升）。比斯利湖伏草隆浓度降低与抗草甘膦棉花的更多使用以及相应地对土壤施用伏草隆除草剂的需求减少有关。相反，在深谷湖从保护性耕作转变为传统耕作后，湖水中伏草隆水平有所增加，推测这是由于传统耕作导致的更大径流量。这些研究表明，在这三个流域观察到的除草剂浓度与作物和土壤管理措施有关。
