Dissolved Pesticide and Organic Carbon Concentrations Detected in Surface Waters, Northern Central Valley, California, 2001-2002

Field and laboratory studies were conducted to determine the effects of
pesticide mixtures on Chinook salmon under various environmental conditions in
surface waters of the northern Central Valley of California. This project was a
collaborative effort between the U.S. Geological Survey (USGS) and the
University of California. The project focused on understanding the
environmental factors that influence the toxicity of pesticides to juvenile
salmon and their prey. During the periods January through March 2001 and
January through May 2002, water samples were collected at eight surface water
sites in the northern Central Valley of California and analyzed by the USGS for
dissolved pesticide and dissolved organic carbon concentrations. Water samples
were also collected by the USGS at the same sites for aquatic toxicity testing
by the Aquatic Toxicity Laboratory at the University of California Davis;
however, presentation of the results of these toxicity tests is beyond the
scope of this report. Samples were collected to characterize dissolved
pesticide and dissolved organic carbon concentrations, and aquatic toxicity,
associated with winter storm runoff concurrent with winter run Chinook salmon
out-migration. Sites were selected that represented the primary habitat of
juvenile Chinook salmon and included major tributaries within the Sacramento
and San Joaquin River Basins and the Sacramento San Joaquin Delta. Water
samples were collected daily for a period of seven days during two winter storm
events in each year. Additional samples were collected weekly during January
through April or May in both years. Concentrations of 31 currently used
pesticides were measured in filtered water samples using solid-phase extraction
and gas chromatography-mass spectrometry at the U.S. Geological Survey's
organic chemistry laboratory in Sacramento, California. Dissolved organic
carbon concentrations were analyzed in filtered water samples using a Shimadzu
TOC-5000A total organic carbon analyzer.

[Summary provided by the USGS.]

本研究开展野外调查与实验室研究，旨在明确加利福尼亚州中央谷地北部地表水环境中，农药混合液对奇努克鲑（Chinook salmon）的影响效应。本项目由美国地质调查局（U.S. Geological Survey, USGS）与加利福尼亚大学联合实施，核心为探究影响农药对幼鲑及其猎物毒性的环境因子。
2001年1月至3月、2002年1月至5月期间，研究团队在加利福尼亚州中央谷地北部的8处地表水采样点采集水样，由USGS分析其中溶解态农药与溶解态有机碳的浓度。USGS亦在上述采样点采集水样，供加利福尼亚大学戴维斯分校水生毒性实验室开展水生生物毒性测试；但本报告未涵盖该类毒性测试结果的呈现内容。本次采样旨在表征与冬季风暴径流相关、且与冬季洄游型奇努克鲑洄游同期的溶解态农药、溶解态有机碳浓度及水生毒性特征。所选采样点覆盖奇努克鲑幼鱼的主要栖息生境，涵盖萨克拉门托河与圣华金河盆地的主要支流，以及萨克拉门托-圣华金三角洲。
在每年的两次冬季风暴事件期间，连续7日每日采集水样；两年的1月至4月或5月期间，额外每周采集一次水样。
研究人员在加利福尼亚州萨克拉门托的USGS有机化学实验室，采用固相萃取-气相色谱-质谱联用法对过滤后水样中的31种现行使用农药进行浓度测定。
采用岛津（Shimadzu）TOC-5000A总有机碳分析仪对过滤后水样的溶解态有机碳浓度进行分析。
[由美国地质调查局（USGS）提供摘要]