Paper No. 79
Presentation Time: 4:30 AM


CONTRERAS, Mara1, LAW, Joshuah D.2, DELGADO, Bianca2 and HEISE, Elizabeth A.2, (1)Department of Environmental Engineering, Texas A&M University - Kingsville, Kingsville, TX 78363, (2)Chemistry and Environmental Sciences, University of Texas at Brownsville, One West University Boulevard, Brownsville, TX 78520,

Located near Brownsville, Texas, San Martin Lake serves as an estuarine water body that receives runoff from drainage ditches that carry, treated effluent, brine concentrate from a brackish groundwater desalination plant, as well as municipal, industrial, and agricultural runoff. San Martin Lake is also connected to the Brownsville Ship Channel were it receives a daily tidal inflow from the Gulf of Mexico up through the ship channel. San Martin Lake's sediment composition is dominated with fine sands and clay. In addition, carbonates were found at the freshwater inlet and ship channel, which can be associated with the presence of oyster beds. The lake is heavily used for recreational activities and fishing because of this water and sediment quality of the area needs to be evaluated.

This study analyzed metal concentrations in the lake water and sediment in June and December 2009, May and August 2010 and March-April 2011. Arsenic, copper and lead were metals found in measurable quantities in both total and dissolved water phases as well as in sediment concentrations. Dissolved water metal concentrations were either above or below standard screening levels computed for dissolved metals depending on the sample collection locations and sampling date. Sediment samples analyzed for these metals were all below standard screening levels. In addition, high variability of metal concentration could be due to the seasonal work performed at the nearby Port of Brownsville. The results suggest that long-term concerns for this area require continued monitoring.