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(I geo ) 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 I geo 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.
KeywordsAnthropogenicHeavy MetalPollutionSedimentOrange River
Mateo-Sagasta, J., Zadeh, S., Turral, H. and Burke, J. (2017) Water Pollution from Agriculture: a Global Review. Food and Agriculture Organization of the United Nations and the International Water Management Institute, Rome.
World Wildlife Fund (2022) Freshwater Systems. https://www.worldwildlife.org/industries/freshwater-systems
Addo-Bediako, A., Tebatso, M., Millicent, K. and Wilmien, L.-P. (2021) Assessment of Heavy Metal Pollution in the Sediments of Dwars River, South Africa. Research Square. (Preprint) https://doi.org/10.21203/rs.3.rs-891267/v1
Tchounwou, P.B., Yedjou, C.G., Patlolla, A.K. and Sutton, D.J. (2012) Heavy Metal Toxicity and the Environment. In: Luch, A., Ed., Molecular, Clinical and Environmental Toxicology, Vol. 101, Springer, Basel, 133-164. https://doi.org/10.1007/978-3-7643-8340-4_6
Yan, T., Zhao, W., Yu, X., Li, H., Gao, Z., Ding, M. and Yue, J. (2022) Evaluating Heavy Metal Pollution and Potential Risk of Soil Around a Coal Mining Region of Tai’an City, China. Alexandria Engineering Journal, 61, 2156-2165. https://doi.org/10.1016/j.aej.2021.08.013
Fashola, M.O., Ngole-Jeme, V.M. and Babalola, O.O. (2016) Heavy Metal Pollution from Gold Mines: Environmental Effects and Bacterial Strategies for Resistance. International Journal of Environmental Research and Public Health, 13, Article No. 1047. https://doi.org/10.3390/ijerph13111047
Srivastava, V., Abhijit, S., Sonu, S., Pooja, S., De Araujo, A.S. and Rajeev, S.P. (2017) Agroecological Responses of Heavy Metal Pollution with Special Emphasis on Soil Health and Plant Performances. Frontiers in Environmental Science, 5, Article No. 64. https://doi.org/10.3389/fenvs.2017.00064
Li, F., Li, X., Hou, L. and Shao, A. (2018) Impact of the Coal Mining on the Spatial Distribution of Potentially Toxic Metals in Farmland Tillage Soil. Scientific Reports, 8, Article No. 14925. https://doi.org/10.1038/s41598-018-33132-4
Singh, N., Gupta, V.K., Kumar, A. and Sharma, B. (2017) Synergistic Effects of Heavy Metals and Pesticides in Living Systems. Frontiers in Chemistry, 5, Article No. 70. https://doi.org/10.3389/fchem.2017.00070
Maanan, M., Mohammed, S., Mehdi, M., Mohamed, C., Omar, A. and Bendahhou, Z. (2015) Environmental and Ecological Risk Assessment of Heavy Metals in Sediments of Nador Lagoon, Morocco. Ecological Indicators, 48, 616-626. https://doi.org/10.1016/j.ecolind.2014.09.034
Aucott, M. (2006) the Fate of Heavy Metals in Landfills: A Review. New Jersey Department of Environmental Protection, New Jersey.
Jan, A.T., Azam, M., Siddiqui, K., Ali, A., Choi, I. and Haq, Q. (2015) Heavy Metals and Human Health: Mechanistic Insight into Toxicity and Counter Defense System of Antioxidants. International Journal of Molecular Sciences, 16, 29592-29630. https://doi.org/10.3390/ijms161226183
Li, F., Yu, X., Lyu, J., Wu, Q. and An, Y. (2022) Assessment of Heavy Metal Pollution in Surface Sediments of the Chishui River Basin, China. PLoS ONE, 17, Article ID: e0260901. https://doi.org/10.1371/journal.pone.0260901
Yan, A., Yamin, W., Tan, S.N., Mohd, Y.M., Ghosh, S. and Chen, Z. (2020) Phytoremediation: A Promising Approach for Revegetation of Heavy Metal-Polluted Land. Frontiers in Plant Science, 11, Article No. 359. https://doi.org/10.3389/fpls.2020.00359
Osamu, W. (2004) What Are Trace Elements?—Their Deficiency and Excess States. Journal of the Japan Medical Association, 47, 351-358.
Bhattacharya, P.T., Misra, S.R. and Hussain, M. (2016) Nutritional Aspects of Essential Trace Elements in Oral Health and Disease: An Extensive Review. Scientifica, 2016, Article ID: 5464373. https://doi.org/10.1155/2016/5464373
Xiao, H., Shahab, A., Xi, B., Chang, Q., You, S., Li, J., Sun, X., Huang, H. and Li, X. (2021) Heavy Metal Pollution, Ecological Risk, Spatial Distribution, and Source Identification in Sediments of the Lijiang River, China. Environmental Pollution, 269, Article ID: 116189. https://doi.org/10.1016/j.envpol.2020.116189
Mahurpawar, M. (2015) Effects of Heavy Metals on Human Health. International Journal of Research-Granthaalayah, 3, 1-7. https://doi.org/10.29121/granthaalayah.v3.i9SE.2015.3282
Alghamdi, A.G., El-Saeid, M.H., Alzahrani, A.J. and Ibrahim, H.M. (2022) Heavy Metal Pollution and Associated Health Risk Assessment of Urban Dust in Riyadh, Saudi Arabia. PLoS ONE, 17, Article ID: e0261957. https://doi.org/10.1371/journal.pone.0261957
Onjefu, S.A., Shaningwa, F., Lusilao, J., Abah, J., Hess, E. and Kwaambwa, H.M. (2020) Assessment of Heavy Metals Pollution in Sediment at the Omaruru River Basin in Erongo Region, Namibia. Environmental Pollutants and Bioavailability, 32, 187-193. https://doi.org/10.1080/26395940.2020.1842251
Abah, J., Mashebe, P. and Onjefu, S.A. (2016) Preliminary Assessment of Some Heavy Metals Pollution Status of Lisikili River Water in Zambezi Region, Namibia. International Journal of Environment and Pollution Research, 4, 13-30.
Du Plessis, A. (2015) Assessment of Heavy Metal Concentrations in Water and Sediment of Dams in Central Namibia and Bioaccumulation of Copper in Locally Occuring Crabs and Fish. Master’s Thesis, University of Namibia, Windhoek.
Dahms, S., Van Der Bank, F.H. and Greenfield, R. (2014) A Baseline Study of Metal Contamination along the Namibian Coastline for Perna perna and Choromytilus meridionalis. Marine Pollution Bulletin, 85, 297-305. https://doi.org/10.1016/j.marpolbul.2014.05.037
Taylor, M.P. and Kesterton, R.G.H. (2002) Heavy Metal Contamination of an Arid River Environment: Gruben River, Namibia. Geomorphology, 42, 311-327. https://doi.org/10.1016/S0169-555X(01)00093-9
Onjefu, S.A., Kgabi, N.A. and Taole, S.H. (2016) Heavy Metal Seasonal Distribution in Shore Sediment Samples Along the Coastline of Erongo Region, Western Namibia. European Journal of Scientific Research, 139, 49-63.
Mufenda, M. and Ellmies, R. (2009) Characterization of Contamination of Stream Sediments and Surface Water at Otjihase Mine, Namibia. Communications of the Geological Survey of Namibia, 14, 41-55.
Muzungaire, L., Mebelo, W., Shuuluka, D. and Omoregie, E. (2012) Preliminary Investigation of Biomagnifications of Trace Metals in the Okavango River, North-Eastern Namibia. Research Journal of Agricultural and Environmental Management, 1, 34-42.
Moisès, D.J., Kgabi, N. and Lewis, E. (2021) Developing a Contamination Susceptibility Index for the Goreangab Dam in Namibia. Physics and Chemistry of the Earth, Parts A/B/C, 124, Article ID: 102916. https://doi.org/10.1016/j.pce.2020.102916
Green Times (2013, December 13) Human Waste, Litter & Chemicals Drown the Orange Rive. Green Times. https://thegreentimes.co.za/human-waste-litter-chemicals-drown-the-orange-river/
Smith, S. (2020) Grape Crop Brings in Millions But Farmworkers Live a Harsh Life. https://www.dailymaverick.co.za/article/2020-12-14-grape-crop-brings-in-millions-but-farmworkers-live-a-harsh-life/
Smith, S. (2020, December 14) Vineyards Pampered, Farmworkers Struggle. The Namibian. https://www.namibian.com.na/207147/archive-read/Vineyards-pampered-farmworkers-struggle
New World Encyclopedia (n.d.) Orange River. https://www.newworldencyclopedia.org/entry/Orange_River
Sullivan, C.A., Dickens, C., Mander, M., Bonjean, M., Macfarlane, D., Bharwani, S., Matin, N., Van Nieukerk, K., Diederichs, N., Taylor, A. and King-Okumu, M.S. (2010) The Orange River Basin. In: Mysiak, J., Jorgen Henrikson, H., Sullivan, C., Bromley, J. and Pahl-Wostl, C., Eds., The Adaptive Water Resource Management Handbook, Earthscan, London, UK, 169 p.
Ramollo, P. (2014) Lower Orange River Forum-Maintaining South Africa’s Largest River. Water Wheel, 13, 40-41.
Geiger, M. (1999) An Explanation of the Geological Map 1: 10000 of the Namibian Borderland Along the Orange River at Zwartbas-Warmbad District-Karas Region-Namibia. Maximilian University of Würzburg, Wuerzburg.
Nakashole, A.N. (2017) Heavy Minerals in the Palaeo and Modern Orange River and Offshore Southern Namibia. PhD Thesis, University of Leeds, Leeds.
Malsiu, A., Shehu, I., Stafilov, T. and Faiku, F. (2020) Assessment of Heavy Metal Concentrations with Fractionation Method in Sediments and Waters of the Badovci Lake (Kosovo). Journal of Environmental and Public Health, 2020, Article ID: 3098594. https://doi.org/10.1155/2020/3098594
Luo, H., Wang, Q., Guan, Q., Ma, Y., Ni, F., Yang, E. and Zhang, J. (2022) Heavy Metal Pollution Levels, Source Apportionment and Risk Assessment in Dust Storms in Key Cities in Northwest China. Journal of Hazardous Materials, 422, Article ID: 126878. https://doi.org/10.1016/j.jhazmat.2021.126878
Withanachchi, S.S., Ghambashidze, G., Kunchulia, I., Urushadze, T. and Ploeger, A. (2018) Water Quality in Surface Water: A Preliminary Assessment of Heavy Metal Contamination of the Mashavera River, Georgia. International Journal of Environmental Research and Public Health, 15, Article No. 621. https://doi.org/10.3390/ijerph15040621
Munyika, S., Kongo, V. and Kimwaga, R. (2014) River Health Assessment Using Macroinvertebrates and Water Quality Parameters: A Case of the Orange River in Namibia. Physics and Chemistry of the Earth, Parts A/B/C, 76-78, 140-148. https://doi.org/10.1016/j.pce.2015.01.001