What are the environmental consequences of nutrient runoff?

The selection of the consequence that nutrient runoff can cause water pollution, eutrophication, and harm aquatic ecosystems highlights the significant environmental impact of excess nutrients entering water bodies. When fertilizers and other nutrient-rich substances wash off fields into rivers, lakes, or oceans, they can lead to an increase in nutrient levels, particularly nitrogen and phosphorus.

This over-enrichment of water bodies causes eutrophication, a process where excessive nutrients stimulate algal blooms. These blooms can deplete oxygen levels in the water, leading to hypoxic or anoxic conditions, which are detrimental to aquatic life. Species that rely on oxygen, such as fish and invertebrates, can suffer from reduced populations or even die-off events due to these low-oxygen conditions.

In addition to creating harmful conditions for aquatic ecosystems, nutrient runoff contributes to water quality issues that can affect drinking water sources and recreational waters. The resulting degradation of aquatic habitats significantly impacts biodiversity, altering food webs and leading to a decline in fish and other aquatic species.

The other options, while related to environmental concerns, do not accurately capture the specific and direct consequences of nutrient runoff in the same way. For instance, while soil erosion is a significant issue, it is not a primary consequence of nutrient runoff alone.