What are major pathways by which phosphorus moves from soils to streams in non-point source pollution?

What are major pathways by which phosphorus moves from soils to streams in non-point source pollution?

• A. Surface runoff carrying phosphate bound to soil particles
• B. Erosion of soil containing phosphorus
• C. Leaching under certain conditions
• D. All of the above

Answer: (D)

Phosphorus moves from soils to streams through several pathways that can occur under different conditions. When rainfall creates surface runoff, phosphorus attached to soil particles is carried with that runoff into streams. Erosion removes soil, and the resulting phosphorus-rich sediment can be flushed or washed directly into water bodies, bringing the nutrient with the eroded material. In addition, phosphorus can move downward through the soil profile by leaching, especially in certain soil types or moisture conditions where dissolved phosphate is less tightly bound; this dissolved phosphorus can enter groundwater and later reach streams via baseflow or springs. Because each of these routes—surface runoff with attached P, erosion of P-containing soil, and leaching to groundwater—can transport phosphorus from soils to streams, all of the above is the correct understanding of major pathways in non-point source pollution.

Phosphorus moves from soils to streams through several pathways that can occur under different conditions. When rainfall creates surface runoff, phosphorus attached to soil particles is carried with that runoff into streams. Erosion removes soil, and the resulting phosphorus-rich sediment can be flushed or washed directly into water bodies, bringing the nutrient with the eroded material. In addition, phosphorus can move downward through the soil profile by leaching, especially in certain soil types or moisture conditions where dissolved phosphate is less tightly bound; this dissolved phosphorus can enter groundwater and later reach streams via baseflow or springs. Because each of these routes—surface runoff with attached P, erosion of P-containing soil, and leaching to groundwater—can transport phosphorus from soils to streams, all of the above is the correct understanding of major pathways in non-point source pollution.