Major Goals and Objectives

it is usually not obvious where a lake’s fixed N comes from. Therefore, understanding the ratios of nitrogen and oxygen isotopes (δ15N and δ18O) in nitrate is crucial for comprehending many environmental media interactions. Fixed N for many lakes comes from fertilizer application, sewage discharge, and atmospheric deposition. But these sources’ exact contribution to the Southern Lake Michigan nitrogen budget is unknown. Recently, several studies have demonstrated the effectiveness of a stable isotope approach in identifying the nitrate sources in various ecosystems, specifically, approaches that utilize dual isotopes to simultaneously analyze δ15N and δ18O nitrate values.

We propose to utilize a dual isotope approach to conduct a comprehensive research study aimed at addressing the environmental issues brought on by nitrate contamination in southern Lake Michigan. The following scientific questions will be the focus of this study.

• What is the concentration of the nitrate pollutant in Southern Lake Michigan?
• What are the contributions of different nitrate pollutant sources?
• How do nitrate pollutant levels vary within Southern Lake Michigan, such as those nearSouth Haven compared to Lake Michigan near Chicago during a single summer season?