| A study was conducted at a site adjacent Roy E. Larsen Sandyland Sanctuary to determine if a suspected oil and brine spill had contaminated the native vegetation at the site. The study site is located on a conservation easement managed by The Nature Conservancy of Texas. An additional oil and brine spill was suspected to have occurred following the landfall of Hurricane Rita in September 2005. The purpose of this study was to determine if an impact had occurred, and if so, to determine the severity of the impact.;Soil samples (0-15cm) were taken in November 2005 and April 2006 from an area of suspected impact and a surrounding forest that was assumed to be non-impacted. The geographic extent of the suspected spill area was determined by observing a 6-acre sized area of saturated soil in the middle of a native forest. Data from soils taken from the area presumed to be impacted was compared to data taken from the surrounding forest soil. Soil was analyzed for moisture concentration, Na, Ca, Mg, NO3, pH, and electrical conductivity (EC). The sodium absorption ration (SAR) was also calculated for all soil samples.;Soil microbiological activity was also assessed to determine if soil microflora had been impacted by the suspected spill. Soil respiration, esterase activity, nitrifying bacteria populations, and soil denitrifying bacteria population were evaluated. Vegetation cover was also assessed to quantify the variation in plant species observed between the water-saturated area of suspected impact and the surrounding forest.;Soil SAR, Mg, NO3, and EC was not significantly different between the two sites, indicating that brine contamination was not a serious threat to native ecology at the site. Soil moisture concentration, Na, Ca, and pH were significantly different between the saturated soil versus the surrounding forest. No soil biological parameters were significantly different between the two sites. Plant species richness and diversity were significantly different. Plant species growing in the study area were identified.;Based on the results of this study, it is concluded that the study site was not contaminated with brine. While an impact may have occurred in the past, current conditions on the site suggest no brine contamination exists. Soil hydrological differences between the suspected impacted site and the surrounding forest probably account for the variation in plant species at the site. It is recommended that no remediation effort be directed at the site. Future studies should determine if hydrocarbon contamination is present at the site. |
