Assessment of Some Heavy Metals and Physico-Chemical Parameters of Surface Water of Matara-Uku Wetlands

Abstract

The study assessed the levels of Nitrogen, Phosphorous and some heavy metals in Matara-Uku wetland. Twenty water samples were collected from surface water of Matara-Uku using polyethene plastic container, the physicochemical parameters of the samples were measured and the samples were analyzed for Nitrogen, Phosphorous and heavy metals. Results from physicochemical analysis are obtained as; pH (7.6 – 8.0), total dissolve solid (70.82 - 84.26 mg/l), electric conductivity (105.0 – 163.0 μs/cm) and temperature (24.4 – 25.4ºC). All the results are in line with World Health Organization standard of 6.5 - 8.5, <600 mg/l, 400 μs/cm and ambient temperature respectively.  The Nitrogen and phosphorous were analyzed using UV- Visible spectrophotometer. From the results, it was found that all the samples had Nitrogen level below the World Health Organization maximum contaminant level of 10 mg/L with a mean concentration range (0.2293 ± 0.0057) mg/L to (2.2455 ± 0.0216) mg/L. Phosphorus was also analyzed and the results indicated that all the sampling sites had phosphorus level above the WHO maximum contaminant level of 0.03 mg/L with a mean concentration range (3.8208 ± 0.4109) mg/L to (4.56 ± 0.1325) mg/L. The water samples were digested using concentrated HCl and HNO3, in which the digested samples were used for heavy metals analysis using Atomic Absorption Spectrophotometer (AAS). The mean concentrations of the heavy metals analyzed were between the ranges Pb (0.1272 ± 0.0445) mg/L to (0.2727 ± 0.1285) mg/L, Cd (0.0026 ± 0.0024) mg/L to (0.0053 ± 0.0054) mg/L and Ni (0.0705 ± 0.0235) mg/L to (0.1411 ± 0.0819) mg/L respectively. Concentrations of Cd and Ni are generally below the maximum permissible limit of 0.03 mg/L and 0.02 mg/L, whereas concentrations of Pb exceeded the maximum permissible limit of 0.01 mg/L for surface water. It was concluded that the surface water of Matara-Uku is polluted with respect to Pb, which is known to bio-accumulate and even undergo bio-magnification in organisms such as fishes and even plants with serious health implications to human being.