Sprague Lori A, Nowell Lisa H
US Geological Survey, Denver Federal Center, Lakewood, CO 80225, USA.
Environ Toxicol Chem. 2008 Feb;27(2):288-98. doi: 10.1897/07-276R.1.
To examine the effect of urban development on pesticide concentrations in streams under low-flow conditions, water samples were collected at stream sites along an urban land use gradient in six environmentally heterogeneous metropolitan areas of the United States. In all six metropolitan areas, total insecticide concentrations generally increased significantly as urban land cover in the basin increased, regardless of whether the background land cover in the basins was agricultural, forested, or shrub land. In contrast, the response of total herbicide concentrations to urbanization varied with the environmental setting. In the three metropolitan areas with predominantly forested background land cover (Raleigh-Durham, NC, USA; Atlanta, GA, USA; Portland, OR, USA), total herbicide concentrations increased significantly with increasing urban land cover. In contrast, total herbicide concentrations were not significantly related to urban land cover in the three remaining metropolitan areas, where total herbicide concentrations appeared to be strongly influenced by agricultural as well as urban sources (Milwaukee-Green Bay, WI, USA; Dallas-Fort Worth, TX, USA), or by factors not measured in the present study, such as water management (Denver, CO, USA). Pesticide concentrations rarely exceeded benchmarks for protection of aquatic life, although these low-flow concentrations are likely to be lower than at other times, such as during peak pesticide-use periods, storm events, or irrigation discharge. Normalization of pesticide concentrations by the pesticide toxicity index -- an index of relative potential toxicity -- for fish and cladocerans indicated that the pesticides detected at the highest concentrations (herbicides in five of the six metropolitan areas) were not necessarily the pesticides with the greatest potential to adversely affect aquatic life (typically insecticides such as carbaryl, chlorpyrifos, diazinon, and fipronil).
为研究城市发展对低流量条件下溪流中农药浓度的影响，在美国六个环境异质的大都市区，沿着城市土地利用梯度在溪流站点采集了水样。在所有六个大都市区，无论流域的背景土地覆盖是农业用地、林地还是灌木地，随着流域内城市土地覆盖的增加，总杀虫剂浓度总体上显著增加。相比之下，总除草剂浓度对城市化的响应因环境背景而异。在三个以林地为主要背景土地覆盖的大都市区（美国北卡罗来纳州罗利 - 达勒姆、美国佐治亚州亚特兰大、美国俄勒冈州波特兰），总除草剂浓度随着城市土地覆盖的增加而显著增加。相反，在其余三个大都市区，总除草剂浓度与城市土地覆盖没有显著关系，在这些地区，总除草剂浓度似乎受到农业以及城市来源（美国威斯康星州密尔沃基 - 格林贝、美国得克萨斯州达拉斯 - 沃思堡）的强烈影响，或者受到本研究未测量的因素（如水资源管理，美国科罗拉多州丹佛）的影响。农药浓度很少超过保护水生生物的基准，尽管这些低流量浓度可能低于其他时期，如农药使用高峰期、暴雨事件或灌溉排放期间。通过农药毒性指数（一种鱼类和枝角类动物相对潜在毒性指数）对农药浓度进行归一化处理表明，检测到的浓度最高的农药（六个大都市区中的五个地区的除草剂）不一定是对水生生物具有最大潜在不利影响的农药（通常是杀虫剂，如西维因、毒死蜱、二嗪农和氟虫腈）。
