A stable isotope approach to nitrate contaminant tracing in the Great Miami River Watershed
The global population has been increasing exponentially and has caused several challenges surrounding sustainability, including the need for greater food production. To meet these demands and boost agricultural productivity, mechanized, more efficient agricultural practices and chemical fertilizers are used. These chemicals have resulted in water pollution and water quality degradation. Much of the Great Miami River Watershed's streams and aquifers are impacted by excessive amounts of nutrients such as nitrate originating from anthropogenic sources including use of fertilizers for agriculture, human wastes (domestic, industrial, and municipal wastes), and urbanization. High nitrate concentrations can cause ecological disturbances and affect organisms across all trophic levels. It also poses a danger to human health (nitrate levels greater than 10 mg/l) if the contaminant reaches drinking water sources. Although a network of water quality monitoring stations report nitrate concentrations in surface and groundwater, contaminant source tracing has not been done. Here we used isotope fingerprinting techniques to trace sources of nitrates. Isotopes of nitrogen (δ15N) and oxygen (δ18O) are used to identify unique nitrate isotopic signature from different sources. Our results show distinct δ15N and δ18O isotopic signatures from different land use and sources such as agriculture, septic systems, and animal waste. Further analysis of boron isotopes (δ11B) is used to distinguish anthropogenic sources (synthetic fertilizer, wastewater) from natural sources (organic fertilizer). Preliminary data has shown that different nitrate sources have different ranges of δ15N, δ18O, and δ11B values. The collective data from our first-round of sampling suggests that the isotopic composition of these sources can be used to quantify contaminants in groundwater that comes from those sources. The outcome of this research could provide a regional baseline for nitrate contaminant tracing and help to inform state and local water quality management and public health policies related to nitrate resources.
Zelalem K Bedaso
Primary Advisor's Department
Stander Symposium poster
"A stable isotope approach to nitrate contaminant tracing in the Great Miami River Watershed" (2018). Stander Symposium Posters. 1235.