Recent studies analyze variations in pesticide retention and leaching through soils of different textures. Sample collection procedures are based on these results showing faster leaching and less retention in coarser-grained, organic-poor soils, relative to fine-grained, organic-rich soils. However, these studies deal with soils formed over long periods of time, characterized by vertical transport of pesticides. Engineered wetlands are a means of reducing surface water contamination from pesticides. To assess the effectiveness of this technology, input of pesticide-laden sediment must be determined. Undisturbed cores within the prograding delta at Blue Creek wetland are correlated using visual and physical descriptions and characterized using GC-ECD to determine influx of adsorbed pesticide during delta development. Because the delta forms much faster than soil horizonation, delta sediments allow data correlation with distinct periods of time and season. Data indicate a better correlation of pesticide content with season than with texture or organic matter content for these sediments. Analyses of only the fine-grained or organic-rich sediments would have resulted in misleading data on loading or degradation rates within the wetland. Through careful monitoring of the progression of the delta throughout the coming years, a very accurate assessment of contaminant fate within the wetland will be documented.
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