Which of the following pollutants in water is not generally attributed to agriculture?

Mercury is the correct answer, as it is typically not associated with agricultural practices. This heavy metal is primarily introduced into water bodies through industrial processes, mining activities, and the combustion of fossil fuels. While agricultural activities can lead to the runoff of nutrients and chemicals such as nitrogen, phosphorus, and pesticides, mercury contamination usually originates from environmental pollution unrelated to farming.

In contrast, nitrogen and phosphorus are commonly linked to agricultural runoff as they are widely used in fertilizers to promote crop growth. Pesticides, used for pest and weed management, can also reach water sources through agricultural runoff. Thus, mercury stands out as a pollutant not generally attributed to agricultural sources.