What is an example of non-point source contamination of ground water?

Non-point source contamination refers to pollution that does not originate from a single, identifiable source. Instead, it comes from widespread areas and often results from precipitation or runoff that carries pollutants into groundwater or water bodies.

Pesticides that dissolve and leach through soil after it rains are a prime example of non-point source contamination. When these pesticides are applied to agricultural fields or landscapes, rain can wash them away, allowing them to penetrate the soil and reach the groundwater. This process is not concentrated in one spot but instead is influenced by the characteristics of the surrounding area, making it difficult to pinpoint a specific source of contamination.

In contrast, options like leaking storage tanks or the direct application of pesticides to water bodies represent point source contaminations, as they can easily be traced back to a singular location. Similarly, improper disposal of pesticide containers falls under point source pollution, because the contamination can be directly linked to the act of disposal. Non-point source contamination, highlighted in the correct answer, reflects the cumulative and diffuse nature of pollution, particularly in agricultural settings.