Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/24/2005
Publication Date: 3/12/2005
Citation: Ouyang, Y., Ou, L.T., Sigua, G.C. 2005. Characterization of pesticide chlordane in estuarine river sediments. Journal of Environmental Quality. 34:544-551. Interpretive Summary: Organic contaminants are ubiquitous in surface environments throughout the world. Most of these contaminants are highly hydrophobic and persist in sediments of rivers and lakes long after their release. The purpose of this study was to investigate the characteristics and spatial distribution of pesticide chlordane in sediments from the Cedar and Ortega rivers. In general, higher chlordane concentrations were found in the Cedar River sediments as compared to those in the Ortega River. This occurred because the water flow velocity in the Cedar River is lower than that of the Ortega River due to the narrower span of the Cedar River. A lower water flow velocity is a favorable condition for sediment associated chlordane accumulations. Our study further revealed that the Cedar River and the north end of the Ortega River had total chlordane concentrations above the PEL value (4.79 ug/kg), which could pose a potential risk to aquatic life. Technical chlordane entering the Cedar and Ortega rivers can remain in the water column adsorbed to suspended solids, which can be transported downstream with normal water flow. Restoration and protection of the Cedar and Ortega rivers have been a challenge and our study may provide crucial information to ensure cost effective remediation. Removing the sediments and associated contaiminants by dredging may be considered to restore the environmental health of the rivers.
Technical Abstract: Sediments are increasingly recognized as both carrier and potential source of contaminants in aquatic environments. This study investigated the characteristics and spatial distribution of total chlordane and its three most abundant compounds, including a-chlordane, y-chlordane, and trans-nonachlor, in sediments from the Cedar and Ortega rivers, Florida, USA using GIS-based kriging analyses and field measurements. Kriging analysis showed that two areas, one from the Cedar River area and the other from the north end of the Ortega River area, were contaminated. The maximum concentrations of total chlordane, y-chlordane, a-chlordane, and trans-nonachlor in the sediments were, respectively, 101.8, 20.1, 26.3, and 19.2 ug/kg in the river sediments. A plot of total organic carbon normalized chlordane concentrations showed that effects of grain size on sediment chlordane contamination were negligible. This study further revealed that a linear correlation existed between y-chlordane and total chlordane (R2 = 0.94) as well as between a-chlordane and total chlordane (R2 = 0.71), whereas no correlation existed between trans-nonachlor and total chlordane (R2 = 0.02). Comparison of total chlordane concentration with Florida Sediment Assessment Guidelines showed that the Cedar River and the north end of the Ortega River had total chlordane concentrations above the probable effect level (4.79 ug/kg), which could pose a potential risk to aquatic life.