The Impact of a Major Hurricane on Sediment Geochemistry and Organic Contaminants of a Shallow Subtropical Estuary Through Strong Resuspension.

Major hurricanes can greatly affect sediment biogeochemical processes in coastal bays and estuaries through strong storm surges and resuspension, yet the impacts on sediment geochemistry have rarely been evaluated. Here, the sediment geochemistry of the Mission Aransas Estuary, Texas, was systematically evaluated prior to and after Hurricane Harvey, a Category 4 storm. The median grain size of the surface sediments in the estuary significantly increased, but the bulk sediment total organic carbon content (TOC%) remained relatively constant. The concentration and composition of several organic chemical classes in the sediment were altered in distinctly different patterns. Accessory pigments showed that cyanobacterial materials in surface sediments increased immediately after Harvey, but returned to pre-Harvey levels 5 months post-hurricane. Pheophorbide decreased significantly after Harvey, but also recovered within 7 months, suggesting resilience of the benthic community. In contrast, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes decreased (5–10 folds) 5 months after Hurricane Harvey and remained low 1 year later. The loss of PAHs and n-alkanes from the sediment might be related to increased solubility due to decreased salinity and strong resuspension during the storm surge. Overall, the strong storm surge and resuspension of sediment by Hurricane Harvey presented a major disturbance to the geochemistry of surface sediment in the MAE, but the impact on individual organic chemical classes depended on their sources, chemical properties, and/or association with fine clay minerals. [ABSTRACT FROM AUTHOR]