Petroleum hydrocarbons in sediments of Upper Laguna Madre

The Laguna Madre system is the largest hypersaline coastal basin in the United States. This system supports the Gulf Intracoastal Waterway (GIWW), and petroleum production wells and pipelines. Sediments from 52 Upper Laguna Madre (ULM) sites were analysed for petroleum hydrocarbons to assess the extent of contamination in the area. The resolved aliphatic hydrocarbons were C7---C21 (0.75–198 μg g−1 dry wt), phytane (16.1–116 μg g−1 dry wt), and pristane (14.9–89.8 μg g−1 dry wt). Aliphatic hydrocarbons with odd and even carbon chain lengths were found to be equally distributed throughout the study sites. The aromatic hydrocarbons resolved were benzene (30.8–44.5 μg g−1 dry wt), methyl naphthalene (9.4–81 μg g−1 dry wt), and dimethyl naphthalene (8.5–721 μg g−1 dry wt). Biogenic and anthropogenic sources are probably contributing to aliphatic hydrocarbon contamination. The sources of aromatic hydrocarbons include leaching from petroleum wells and pipelines and industrial surface run-off.