What should be monitored to determine contamination in water sources?

Monitoring nitrate nitrogen concentrations is crucial for determining contamination in water sources because elevated levels of nitrates can indicate agricultural runoff or wastewater contamination. Nitrates often originate from fertilizers, sewage, and septic systems, and their presence in drinking water can pose health risks, particularly to infants, as it can lead to a condition known as methemoglobinemia, or "blue baby syndrome."

Nitrate testing is a common practice in water quality assessments because it helps identify both point and non-point source pollution. Regular monitoring of these concentrations allows for the detection of contamination trends over time and helps to implement necessary actions to mitigate the risks associated with high nitrate levels.

While other factors such as oxygen levels, mineral levels, and fluoride levels can also provide information about water quality, they do not specifically identify contamination as directly or effectively as nitrate nitrogen concentrations do.