Semester of Graduation
2023 Fall
Degree
Master of Science (MS)
Department
School of Renewable Natural Resources
Document Type
Thesis
Abstract
The Calcasieu River is an important shipping channel for petrochemical industries in Louisiana to the northern Gulf of Mexico. There are concerns over metal pollution in the river water and sediment. To better understand the pollution potential of metals in the estuarine river, we measured concentrations of metals in the river water and riparian sediment. Water and sediment samples were collected at six sites along the last 88 km reach of the Calcasieu River monthly between May 2013 and November 2015, during which salinity ranged from 0.02 to 29.5 ppt from upstream to downstream. The samples were analyzed for aluminum (Al), arsenic (As), boron (B), cadmium (Cd), calcium (Ca), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lithium (Li), magnesium (Mg), manganese (Mn), nickel (Ni), silicon (Si), titanium (Ti), vanadium (V), and zinc (Zn). In the freshwater portion of the river, Si, Ca, Al, Fe, and Mg showed the highest concentration (8, 5, 4, 2, and 2 mg/L, respectively), while Li, As, Zn, Ti, and B had the lowest concentration (6, 16, 27, 34 and 50 μg/L, respectively). The concentrations of Al and Si in the river water declined by more than 30% from the freshwater to the river mouth, but the concentrations of Li and B increased by 61 and 66 times, respectively. None of these metals’ concentrations were found to exceed US EPA standards. The average concentration of heavy metals in riparian sediments were in the decreasing order of: Zn > Cr > Cu > Pb >As > Ag > Cd. Contamination factor (CF) demonstrated that most sediment samples were moderately to heavily contaminated by As, Cd, and Ag. The pollution load index (PLI) values of these metals were above one (>1), indicating progressive deterioration of the sediment quality. Further studies on metal transport are needed to understand the metal sources and their potential effects on coastal aquatic ecosystems.
Date
8-21-2023
Recommended Citation
Wu, Zhenwei, "Geochemical Study on Metal Distribution in a Lowland River from Freshwater to Saltwater near the Northern Gulf of Mexico" (2023). LSU Master's Theses. 5838.
https://repository.lsu.edu/gradschool_theses/5838
Committee Chair
Xu, Yi-Jun