Sediments and Water Column Contamination by Heavy Metals in Ekulu River, Nigeria: Ecological and Human Health Risk Assessment

Abstract

Acid mine drainage from a defunct coal mine, agricultural run-off and indiscriminate waste disposal constitute major threat to the quality of Ekulu river of Enugu State, Nigeria. In this study, Ekulu river sediments and water column pollution by heavy metals and the associated ecological and human health exposure risks were assessed. The heavy metals were measured using atomic absorption spectrometry. The parameters used in assessing the pollution of the sediments were contamination factor, contamination degree, geochemical accumulation index and pollution load index whereas the ecological risk of the heavy metals in the sediments was assessed using potential ecological risk index. The parameters employed in assessing the carcinogenic and non-carcinogenic risks of exposure by humans to the heavy metals were hazard index and risk index. The results obtained indicate that the chromium and lead input into the sediments around the defunct coal mine area during the wet season was significant and most probably due to the discharge of acid coal mine drainage into the river. Elevated values of ecological and human health exposure risks around 4 km distance away (Damija) from the defunct coal-mine area are most likely due to anthropogenic activities.

Ecological pollution and health risk monitoring assessment of polycyclic aromatic hydrocarbons and heavy metals in surface water, southeastern Nigeria

“…The total mean concentration of heavy metals is presented in Table 8 , as we can see that arsenic was absent across the three sampled stations A, B and C, which could be low detection limit of instruments, which is in agreement with previous studies conducted by Ugochukwu et al [ 31 ] in urban groundwater and water supply system in Enugu state, Nigeria. Cadmium was present in station A only, which was within USEPA and WHO limit of 0.005mg/l and 0.003mg/l.…”

“…However, limited similar studies have been carried out in surface water from Ekulu at the Enugu metropolis. Ugochukwu et al [ 31 ] and Ugochukwu et al [ 32 ] only studied heavy metals and PAHs on sediments from Enugu. No reports have been given on pollution status and public health assessment of heavy metals and PAHs in cumulative surface water from River Ekulu flowing across production industries in Enugu city which is about 1.5 – 3 kilometers away from the river.…”

“…The coal fields (Iva valley, Onyeama, and Ribadu mines) are situated at the upper course of the Ekulu River with an inflow of acid mine drainage from these abandoned coal fields whereas, in the lower course, the river is utilized by Abakpa and Emene populace for refuse dumping, agricultural, industrial, domestic and swimming [ 35 - 36 ]. Effluent runoffs from paint, abandoned coal mines, allied, pharmaceutical, automobile, and food processing industries sited within the locations of the river bank loaded with various forms of pollutants are leached into the water body [ 31 ], thus calls for serious concern. The inhabitants within the River settlements also use the river as a dumping medium for waste and domestic effluents.…”