Submitted to: United States Environmental Protection Agency Chesapeake Bay Program Report
Publication Type: Abstract Only
Publication Acceptance Date: October 28, 2000
Publication Date: N/A
Technical Abstract: Riparian buffer zones should remove agricultural contaminants before they reach a stream, through storage and sequestration within the riparian soils, or by intrinsic bioremediation by soil microbial activity. In this study, we are assessing the function of a riparian wetland by measuring the amount of agricultural contaminants in the groundwater, surface runoff, and dwithin the stream. Our results show that significant contamination of surface water can occur even with filtering of agricultural waters through riparian buffers. Structural heterogeneity within the wetland soils can greatly affect overall function. There is considerable spatial variability in soil biological activity within the wetland. If nitrate-enriched groundwater travels preferentially through discreet soil zones of limited activity, the nutrient removal capabilities of the system are substantially reduced. An extensive network of macropores (large defined pores or conduits within the soil structure) delivers nutrient-rich water directly into primary and secondary stream channels within the flood plain. The presence of these preferential flow paths (interconnected macropores and highly conductive sand layers) can significantly reduce the capacity of a riparian buffer strip to remove agricultural contaminants.