Date of Award

May 2020

Degree Type

Thesis

Degree Name

Master of Science

Department

Geosciences

First Advisor

Shangping Xu

Second Advisor

Yin Wang

Committee Members

Shangping Xu, Yin Wang, Timothy J Grundl

Abstract

The professional lawn care business has developed into a multibillion-dollar industry over the last few decades with a rise in home and garden market sector for urban/suburban use. Some homeowners purchase and apply the pesticides themselves while others hire professional lawn care companies. The US EPA states that “all pesticides are toxic to some degree” and the prevalent, widespread use of pesticides is both a major environmental problem and a public health issue. There have been many studies tracing agricultural pesticides application and contamination of public drinking water, and less on (sub)urban, residential pesticide application. This study targets active, private wells within four Wisconsin counties in the Milwaukee metropolitan area: Milwaukee, Ozaukee, Washington, and Waukesha, which consist of large portions of non-agricultural, suburban land use. The groundwater samples collected were tested for seven pesticide compounds that are active ingredients in some of the most commonly applied residential pesticides: 2,4−Dichlorophenoxyacetic Acid (2,4-D), Carbaryl, Dicamba, imidacloprid, Malathion, 2-methyl-4-chlorophenoxyacetic acid (MCPA), and methylchlorophenoxypropionic acid (MCPP). Of these seven compounds, only three (2,4-D, Carbaryl, and Dicamba) have health-based enforcement standards, and none of them have a maximum contaminant level.

In this study, 16 active, private wells were sampled; two in Milwaukee county, four in Ozaukee county, six in Washington county, and four in Waukesha county. These wells were selected primarily based on their location within well-kept, more densely populated, suburb neighborhood, away from agricultural fields, to ensure the groundwater collected was representative of residential pesticide application. Samples were collected during June/July, August/September, and November of 2019, and February 2020 and analyzed for 2,4-D, carbaryl, dicamba, imidacloprid, malathion, MCPA, and MCPP. There were seven wells that detected one or more of the targeted pesticides between June and August, no other sampling event resulted in any pesticide detections. The pesticide most frequently detected being 2,4-D, showing up in three separate wells, followed by malathion showing up in two wells; carbaryl, dicamba, MCPA, and MCPP each making an appearance once.

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