What is a common indicator of nutrient pollution in water?

The choice of nitrate concentration as a common indicator of nutrient pollution in water is rooted in its significant influence on aquatic ecosystems. Nitrates are a major component of nutrient pollution, which can lead to excessive growth of algae and other aquatic plants, a process known as eutrophication. This phenomenon can deplete oxygen levels in water bodies, adversely affecting fish and other aquatic life.

Nitrates enter water systems primarily from agricultural runoff, which includes fertilizers, as well as from wastewater discharges. High levels of nitrate can indicate that nutrient loads are entering a water body, which can result in serious ecological consequences. This makes monitoring nitrate concentration an important aspect of managing water quality.

While phosphates (mentioned in the first choice) are also a critical indicator of nutrient pollution, nitrates are particularly common in many freshwater and coastal environments, often leading to concerning levels of algae blooms. Chlorine, used primarily as a disinfectant in water treatment processes, is less directly tied to nutrient pollution concerns. Ammonia can also indicate nutrient pollution, but it primarily affects water quality in different contexts and is less commonly monitored than nitrate in relation to nutrient loading.