Sourcing of Dioxins from the San Jacinto Waste Pit Superfund Site into the Galveston Bay System

In 1965 and 1966, dioxin laden paper mill wastes were disposed of in the San Jacinto River Waste Pits (SJWP) on the banks of the San Jacinto River (SJR). Regional land subsidence has caused submergence of portions of the waste pits, directly exposing the wastes to the SJR. This thesis is aimed at quantifying the contribution of the SJWP to the observed dioxin pollution in water, sediment, and tissue samples collected from the Galveston Bay System (GBS). A qualitative investigation of dioxin fingerprints in sediments identified 3 primary source profiles most likely representing dioxins from a) SJWP (paper mill), b) the Houston Ship Channel (HSC) upstream of its confluence with the SJR, and c) Houston’s urban air. A quantitative source apportionment model, positive matrix factorization (PMF), identified similar source profiles and indicated that industrial point sources have a significant impact on nearby sediment quality within the HSC and SJR; however, atmospheric deposition is the dominant source of dioxins observed in the more open waters of Galveston and Trinity Bays. PMF results also indicate the locations within the GBS where the SJWP affected sediment quality. An EFDC model of the GBS was used to aid in the understanding of the complex hydrodynamics of the system. Model results provide supporting evidence of SJWP dioxin laden sediment transport and deposition within the GBS.