Analysis Of Physico-Chemical Parameters And Selected Heavy Metals In Aquatic Ecosystems

Abstract

Abstract The quality of aquatic ecosystems is of great concern. Elevation of pollutants in water could cause health disorders in human and destabilize the aquatic ecosystem. The case study investigated quality of water from five sites of Lake Turkana selected based on proximity to potential anthropogenic pollution sources. Temperature,

pH, electrical conductivity (EC), dissolved oxygen (DO), salinity, total dissolved solids (TDS) and Oxidation- Reduction Potential (ORP) were measured at the site using YSI Pro 1030 Multiparameter electrode while

nitrates and phosphates were determined at Kenyatta University’s food science laboratory using Vis 130 Spectrophotometer. Selected heavy metals (lead, cadmium and chromium) were determined using flame atomic absorption spectroscopy. Sampling was performed in triplicates during the dry season. The results were: temperature (28.24±0.96 to 28.86±0.38°C), pH (9.04±0.21 to 9.46±0.06), electrical conductivity (281.57±0.41 to 289.46±3.95 Ωcm-1

), dissolved oxygen (6.3±0.79 to 7.04±0.05 mg/L), salinity (1.67±0.00 to 1.70±0.01 ppt), TDS (2093.4±0.39 to 2135.8±4.86 mg/L), ORP (-54.22±0.12 to 588.14±0.51 mV), nitrates (5.52±0.31 to 10.04±1.82 mg/L) and phosphates (0.47±0.06 to 0.72±0.15 mg/L). Water lead (0.11±0.01 to 0.12±0.00 mg/L), cadmium (0.00±0.00 to 0.03±0.00 mg/L) and chromium (0.01±0.00 to 0.03±0.01 mg/L). The results showed that pH and TDS were beyond WHO standard of 6.5-8.5 and 600.0 mg/L respectively while phosphates exceeded USEPA limit of 0.024 mg/L in all sites. The electrical conductivity and nitrates complied with WHO standards of 400.0 Ωcm-1 and 50.0 mg/L respectively while the other parameters were not guided by WHO. The lead levels in water exceeded WHO standard of 0.01 mg/L in all sites. The cadmium levels in Impressa and Long’ech beaches in the upstream section exceeded WHO standard of 0.003 mg/L. However, chromium complied with WHO standard of 0.05 mg/L in all sites. These calls for measures keep all the parameters under surveillance to ensure water quality is maintained.