Abstract
Global water shortage is caused not just by the physical scarcity of water, but also by gradual deterioration of the quality of water resources such as lakes, streams and rivers with heavy metals. This present study evaluated the status of Mn, Fe, Cr, Cu, Ni, As, Zn, Pb and Cd in sediments from the lower Orange River by Inductively Coupled Plasma Atomic Emission Spectrometry technique by collecting a total of eleven samples, each weighing 1 - 2 kg at the depth of 15 - 20 cm from two observations sites along the lower Orange River and applying pollution indicators such as contamination factor(CF), pollution load index(PLI), index of geo-accumulation(Igeo) and enrichment factor(EF) to assay the nature and extent of heavy metals contamination in sediments. The sequence of the total heavy metal content in descending order was Fe > Mn > Cr > As > Zn > Ni > Cu > Pb > Cd. The results of CF and Igeo showed Mn, Cd, Ni, Zn and Pb were minor sources of sediment contamination since most of the samples were unpolluted and moderately polluted by these metals. However, most sediments were moderate to considerably polluted with Cr, As and Fe suggesting that these were the major pollution sources. The value of PLI at one of the two observation sites was equivalent to the value of baseline level, while the next site indicted quality deterioration of the sediments. The EF revealed that Cr was moderately enriched and arsenic (As) significantly enriched in all the sediments, which suggested contamination due to anthropogenic intervention. Hence, it is recommended that sediment quality be evaluated on a regular basis to avoid further deterioration of the Orange River’s health, which might have detrimental repercussions for both aquatic life and local communities along the river.
Highlights
Despite the fact that global emphasis has been focused on water capacity, efficiency, and distribution, incompetent wastewater management has resulted in major water-quality issues in many regions of the world, exacerbating the water crisis
Global water shortage is caused not just by the physical scarcity of water, and by gradual deterioration of the quality of water resources such as lakes, streams and rivers with heavy metals. This present study evaluated the status of Mn, Fe, Cr, Cu, Ni, As, Zn, Pb and Cd in sediments from the lower Orange River by Inductively Coupled Plasma Atomic Emission Spectrometry technique by collecting a total of eleven samples, each weighing 1 - 2 kg at the depth of 15 - 20 cm from two observations sites along the lower Orange River and applying pollution indicators such as contamination factor(CF), pollution load index(PLI), index of geo-accumulation(Igeo) and enrichment factor(EF) to assay the nature and extent of heavy metals contamination in sediments
Based on the results obtained from the analysis of physicochemical parameters of sediments from the lower Orange River, it was found that the pH of all samples was within the World Health Organization (WHO) and Environmental Protection Agency (EPA) recommended range for domestic use
Summary
Despite the fact that global emphasis has been focused on water capacity, efficiency, and distribution, incompetent wastewater management has resulted in major water-quality issues in many regions of the world, exacerbating the water crisis (water insecurity). Global water shortage is caused not just by physical scarcity, and by the gradual degradation of water quality in many countries and the amount of water that is safe to use is of a limited amount [1] Freshwater bodies such as lakes, reservoirs, ponds, rivers, streams, wetlands and groundwater which represent only 3% of all the water on earth are under threat from a myriad of anthropogenic forces [2]. Large volumes of waste are produced and discharged in the environment in various paths including waste runoff as a result of mineral processing and metallurgical extraction to retrieve the needed elements [6] Agricultural works such as the application of fertilizers, pesticides, waste water, biosolid and manure contribute to the accumulation of heavy metals in the ecosystem [7]. Practices such as discharge of domestic effluents into water bodies and improper disposal of domestic waste by open dumping and poor management of landfills introduce heavy metals in the natural environment [10] [11]
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