Submitted to: American Water Resources Association Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2004
Publication Date: 6/29/2004
Citation: Angier, J., McCarty, G.W., Rice, C., Bialek-Kalinski, K.M. 2004. Critical areas in riparian buffers: Improving contaminant remediation function by identifying zones with limited mitigation capacity [abstract]. American Water Resources Association Conference Proceedings, June 2004.
Technical Abstract: First-order riparian buffers are often considered the best line of defense in mitigating potential agricultural pollution, but the capacity for contaminant remediation can vary spatially and temporally within a single ecosystem. Research conducted at a small watershed in the mid-Atlantic coastal plain of Maryland indicated that certain areas in the riparian zone consistently contributed disproportionately to total exported stream contaminant loads. Source areas of groundwater-contributed agrochemicals were relatively small, focused, and stable. One area of the riparian floodplain, a zone of enhanced groundwater exfiltration to the surface, accounted for ~35% of total annual exported stream nitrate, but comprised 0.006% of the riparian zone. Pesticide metabolites that were transported through groundwater also tended to surface in these foci of groundwater exfiltration. Areas such as these ("critical areas") limit the mitigation capacity of the entire ecosystem. Preferential subsurface flow appeared to be responsible for determining where these areas occurred. Identifying critical areas is necessary to assess the impact of agrochemicals on the environment. Current regulations and design specifications that assume uniform mitigation capacity within a riparian zone are not optimal; reevaluating riparian buffers in terms of critical and non-critical areas should allow more resources to be allocated for limiting the contamination potential from critical areas and thus improve overall riparian zone mitigation capability.