A study of heavy metals in soils of the former United States naval base, Argentia, Newfoundland

Palanisamy, Giriprakash (2001) A study of heavy metals in soils of the former United States naval base, Argentia, Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

In contaminated landfill sites, sorption, desorption and mobility of contaminants are important properties that should be studied thoroughly before taking any remedial measures. Samples from five soil sections were taken from a landfill site at the former United States Naval facility at Argentia, Newfoundland. Total metal contents were analyzed by XRF and ICP-MS. Available cadmium content was determined by the EDTA extraction method using GF- Atomic Adsorption Spectrometry. High levels of Sr, Zn, Pb, Fe, Ti and Zr were found in these soil samples. Soil samples have variable pH (4.64 to 7.78), organic carbon content (0.03 to 7.49 %), CEC (0.6 to 10.2 cmole(+)/Kg), bulk density (0.994 to 0.638 Mg/m³) and soil texture (as sandy, sandy loam, sandy clay loam, loamy sand, loam, silty loam and clay loam). They are classified using USDA soil textural classification. -- Batch sorption and desorption experiments were carried out for all samples, and Freundlich isotherms and equations were developed. The results showed that Cd sorption increased with increasing depth in two sections and decreased in another section, whereas the other sections showed a variable behavior. Cadmium sorption increased with increasing soil pH, organic carbon content and clay content, whereas it decreased with increasing sand percentage. -- The results revealed a possible relationship between Cd sorption and associated anions. In particular, sorption decreased with increasing C1 content of the soil samples in section V. This was attributed to the formation CdC1⁺, which is less readily sorbed than Cd. The results of desorption experiments showed a positive relationship between sand content and Cd²⁺ desorption. The amount of Cd retained in profile IV decreased with increasing calcium content, which might be due to the competition of calcium for Cd sorption sites. -- A possible relationship between the pH and sand content with Cd mobility was studied by soil thin layer chromatography. The soil samples that showed lower pH values and higher sand percentage also showed high Cd mobility; therefore, the lower the pH and higher the sand percentage, the higher will be the Cd movement to the lower soil layers and groundwater.

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