Rosen Michael R, Lapham Wayne W
U.S. Geological Survey, 2730 North Deer Run Rd., Carson City, NV 89701, USA.
J Environ Qual. 2008 Sep-Oct;37(5 Suppl):S190-8. doi: 10.2134/jeq2008.0049.
Assessment of temporal trends in national ground-water quality networks are rarely published in scientific journals. This is partly due to the fact that long-term data from these types of networks are uncommon and because many national monitoring networks are not driven by hypotheses that can be easily incorporated into scientific research. The U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) since 1991 has to date (2006) concentrated on occurrence of contaminants because sufficient data for trend analysis is only just becoming available. This paper introduces the first set of trend assessments from NAWQA and provides an assessment of the success of the program. On a national scale, nitrate concentrations in ground water have generally increased from 1988 to 2004, but trends in pesticide concentrations are less apparent. Regionally, the studies showed high nitrate concentrations and frequent pesticide detections are linked to agricultural use of fertilizers and pesticides. Most of these areas showed increases in nitrate concentration within the last decade, and these increases are associated with oxic-geochemical conditions and well-drained soils. The current NAWQA plan for collecting data to define trends needs to be constantly reevaluated to determine if the approach fulfills the expected outcome. To assist this evaluation, a comparison of NAWQA to other national ground-water quality programs was undertaken. The design and spatial extent of each national program depend on many factors, including current and long-term budgets, purpose of the program, size of the country, and diversity of aquifer types. Comparison of NAWQA to nine other national programs shows a great diversity in program designs, but indicates that different approaches can achieve similar and equally important goals.
关于国家地下水质量监测网络时间趋势的评估很少在科学期刊上发表。部分原因在于,这类网络的长期数据并不常见,而且许多国家监测网络并非由能够轻易纳入科学研究的假设驱动。自1991年以来,美国地质调查局(USGS)的国家水质评估计划(NAWQA)截至2006年一直专注于污染物的出现情况,因为用于趋势分析的足够数据才刚刚可得。本文介绍了NAWQA的首批趋势评估,并对该计划的成效进行了评估。在全国范围内,1988年至2004年期间,地下水中硝酸盐浓度总体上有所上升,但农药浓度的趋势不太明显。在区域层面,研究表明,高硝酸盐浓度和频繁检测到农药与化肥和农药的农业使用有关。在过去十年中,这些地区大多硝酸盐浓度有所上升,且这些上升与氧化地球化学条件和排水良好的土壤有关。当前NAWQA收集数据以确定趋势的计划需要不断重新评估,以确定该方法是否能实现预期结果。为辅助这一评估,对NAWQA与其他国家地下水质量计划进行了比较。每个国家计划的设计和空间范围取决于许多因素,包括当前和长期预算、计划目的、国家规模以及含水层类型的多样性。将NAWQA与其他九个国家计划进行比较表明,计划设计存在很大差异,但也表明不同方法可以实现相似且同样重要的目标。