Rayne Todd W, Bradbury Kenneth R, Krause Jacob J
Wisconsin Geological and Natural History Survey, University of Wisconsin - Extension, 3817 Mineral Point Rd, Madison, WI 53705.
Ground Water. 2019 Mar;57(2):279-291. doi: 10.1111/gwat.12666. Epub 2018 May 8.
A rural subdivision in south central Wisconsin was instrumented with monitoring wells and lysimeters before, during, and after its construction to examine the impacts of the unsewered subdivision on groundwater quality and quantity. Prior to construction, the 78-acre (32 ha) site was farmland. Sixteen homes were constructed beginning in 2003. Initial monitoring from 2002 to 2005 showed that groundwater beneath the site had been impacted by previous agricultural use, with nitrate-N values as high as 30 mg/L and some detections of the herbicide atrazine. Our 12-year study shows that the transition from agricultural to residential land use has changed groundwater quality in both negative and positive ways. Although groundwater elevations showed typical seasonal fluctuations each year, there were no measurable changes in groundwater levels or general flow directions during the 12-year study period. Chloride values increased in many wells, possibly as a result of road salting or water softener discharge. Nitrate concentrations varied spatially and temporally over the study period, with some initial concentrations substantially above the drinking water standard. In some wells, nitrate and atrazine levels have declined substantially since agriculture ceased. However, atrazine was still present at trace concentrations throughout the site in 2014. Wastewater tracers show there are small but detectable impacts from septic effluent on groundwater quality. Particle traces based on a groundwater flow model are consistent with the hypothesis that septic leachate has impacted groundwater quality.
在威斯康星州中南部的一个乡村分区建设之前、期间和之后，都安装了监测井和蒸渗仪，以研究这个没有下水道系统的分区对地下水质量和水量的影响。在建设之前，这个78英亩（32公顷）的场地是农田。从2003年开始建造了16所房屋。2002年至2005年的初步监测表明，该场地下方的地下水受到先前农业活动的影响，硝酸盐氮值高达30毫克/升，还检测到了除草剂阿特拉津。我们为期12年的研究表明，从农业用地向住宅用地的转变对地下水质量产生了正负两方面的影响。尽管每年地下水位都呈现出典型的季节性波动，但在为期12年的研究期间，地下水位或总体水流方向没有可测量的变化。许多井中的氯化物值有所增加，可能是道路撒盐或软水器排放的结果。在研究期间，硝酸盐浓度在空间和时间上有所变化，一些初始浓度大大高于饮用水标准。在一些井中，自农业活动停止以来，硝酸盐和阿特拉津水平大幅下降。然而，2014年整个场地仍有痕量浓度的阿特拉津存在。废水示踪剂表明，化粪池污水对地下水质量有微小但可检测到的影响。基于地下水流模型的颗粒追踪结果与化粪池渗滤液影响地下水质量这一假设一致。
