What does leaching refer to in the context of pesticides?

Leaching refers specifically to the process through which pesticides are carried away from the target application area, often down through the soil profile, and into the groundwater or surface water systems. This movement can occur when rainwater or irrigation water percolates through the soil, dissolving the pesticides and allowing them to travel downward and potentially affect water quality. Understanding leaching is critical for environmental protection and ensuring that pesticide use does not adversely affect water resources.

The other options describe different processes related to pesticides. For example, absorption involves how plants take in pesticides through their roots or leaves, while breakdown and chemical alteration pertain to the degradation processes that affect pesticide efficacy and environmental persistence. However, they do not encapsulate the concept of leaching itself, which is focused on the transport and potential dispersal of chemicals away from the original application area into other environmental compartments.