Date of Award
Master of Science - Natural Sciences
Chemistry and Biochemistry
Dr. Michael Janusa
Dr. Kenneth Farrish
Dr. Xiaozhen Han
Dr. Kefa Onchoke
The concentrations of metals (Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, Zn) were investigated in soil and water samples collected over four different sites in the southern part of Lake Nacogdoches over one year from August 2018 through June 2019. Water samples were analyzed using the USEPA method 200.8 part 11.2 for total recoverable metals. Soil samples were analyzed using the USEPA method 3050B for total recoverable metals. Although the total concentration gives some indication of the level of contamination, it is not enough to give information on the bioavailability or mobility of the element. A modified Tessier soil sequential extraction procedure was used to determine the speciation of metals in soil samples. Thus, elements in soils are present in various physicochemical forms, which in turn influences its bioavailability. In this study, soil samples were separated into five fractions: exchangeable, adsorbed, organic bonded, carbonate, residual fraction (F1-F5). The reliability of the total metal concentration from the digestion of bulk sediment were summed and compared withthe sequential extractions of the same bulk sediment for the metal concentrations of the fractions F1–F5. High recovery rates (≥ 5 mg metal/kg soil) indicate a good reliability for majority of metals studied using the sequential extraction procedure. The metal concentrations at the ppb level were determined by using inductively coupled plasma mass spectrometry (ICP-MS). The results indicate that the water samples had Ba, Mn, and Sr at concentrations greater than 35 ppb for majority of samples. The soil samples had Ba, Co, Cr, Mn, Ni, Pb, V, and Zn at concentrations greater than 10 mg metal/kg soil for majority of samples, with Ba, Mn, and V showing the highest values (greater than 60 mg metal/ kg of soil). All metal concentration was well below the WHO and EPA drinking water standards for metals and in the typical range found in natural waters.
Taiwo, OLawunmi, "Evaluation of Metal Concentration in Water and Soil in the Southern Region of Lake Nacogdoches" (2020). Electronic Theses and Dissertations. 332.
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