Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 25, 2003
Publication Date: March 25, 2003
Citation: Angier, J., McCarty, G.W. 2003. Climatic controls on nutrient processing and export in a riparian wetland [abstract]. Abs. 9. BARC Poster Day. Technical Abstract: Riparian zones can sequester or remove agricultural contaminants from surface and ground water by microbial activity within the riparian wetland soil, through uptake by vegetation in the wetland, and by in-stream nutrient processing. However, this remediative function varies greatly according to weather conditions, especially rainfall. A small agricultural watershed in the BARC-East research area has been the site of a riparian zone study for six years. Nitrate exported by the first-order stream in the riparian zone is five times greater during a year with average rainfall than during a dry year. Increased nitrate in exported stream water is the result of a variety of factors. Contaminated groundwater emerges onto the land surface more rapidly, and to a greater extent, under wetter, higher rainfall conditions. This lessens the contact time between the groundwater and potentially nitrate-reducing wetland soil. A greater proportion of this emerging groundwater travels through subsurface preferential flowpaths (such as macropores), lessening the contact area between the groundwater and soil. Plant uptake of nutrients is not unlimited; excess water (beyond the amounts needed by vegetation) ends up in the stream channel, along with its contaminant load. Higher stream flows decrease the in-stream residence time and flush out those stagnant or slow-moving stream sections where nutrient processing is most likely to occur. Therefore, climate change is likely to impact the ability of riparian ecosystems to remove agricultural contaminants.