What is a common cause of nitrate contamination in water?

Nitrate contamination in water is often linked to the use of fertilizers in agricultural practices. Fertilizers typically contain high levels of nitrates, which can leach into groundwater and surface water through runoff and infiltration. When it rains or when water is applied for irrigation, excess nitrates from fertilized soil can be washed away, leading to elevated nitrate levels in nearby water sources.

In addition to fertilizers, the processes associated with oil and gas exploration can also contribute to nitrate contamination, though this is typically not as common as agricultural sources. The extraction processes may release various chemicals that can alter the geochemical balance in surrounding areas, potentially leading to increased nitrate levels in nearby water systems.

While leaking septic tanks can also lead to the introduction of nitrates into groundwater due to the breakdown of organic matter, agricultural fertilizers are generally the primary and more pervasive source of nitrate contamination, particularly in rural areas. Thus, the connection of fertilizers and oil and gas processes to nitrate contamination makes this the most accurate choice.