Environmental Health Risks Due to Anthropogenic Metals in Mtoni Estuary Ecosystem and its Environs, Tanzania


  • M. J. Mihale


Mangrove sediment samples from Kizinga and Mzinga creeks of Mtoni estuary were analysed for metals (Al, Fe, Mn, Cr Ni, Cu, Zn, As, Sr, Cd and Pb) to determine their current levels and their anthropogenic impact in a tropical estuarine environment. Standard sampling techniques were used. Samples were digested using a CEM Microwave Accelerated Reaction System (MARS) and analysis was carried out using a High Resolution Inductively Coupled Plasma Mass Spectrometer (HRICP-MS). Sandy particles were dominant, with < 6% of OM in estuary and < 9% in tributaries. Metal levels showed neither distinct depth gradient nor variation between seasons. A clear gradient from upstream of Kizinga and Mzinga rivers to estuarine mouth was observed. Pearson correlation matrix, Principal component analysis (PCA) and Enrichment factors (EF) indicated that most metals in Mtoni estuary probably originated from anthropogenic activities except Sr that was probably derived from natural origin. Levels of anthropogenic pollutants are indicative of human induced environmental change and have repercussions on environmental and human health as well as future status of estuary.

Author Biography

M. J. Mihale

Department of Physical Sciences, Open University of Tanzania,  P. O. Box 23409, Dar es Salaam


Acevedo-Figueroa, D., Jiménez, B. D., Rodríguez-Sierra, C. J. (2006). Trace metals in sediments of two estuarine lagoons from Puerto Rico, Environmental Pollution141 (2): 336-342.

Ak’habuhaya, J., and Lodenius, M. (1988). Metal pollution of River Msimbazi, Tanzania, Environmental International, 14: 511-514.

Alaoui, A. M., Choura, M., Maanan, M., Zourarah, B., Robin, M., Conceição, M. F., Andrade, C., Khalid, M., and Carruesco, C. (2010). Metal fluxes to the sediments of the Moulay Bousselham lagoon, Morocco, Environ Earth Sci, 61: 275–286.

Baeyens W, S. Panutrakul, M. Leermakers, J.,and Navez, M. E. (1991). Geochemical processes in sandy and muddy sediments, Geo-Marine Letters 11-3/4: 188-193.

Chatterjee M, Silva Filho, E. V., Sarkar, S. K., Sella, S. M., Bhattacharya, A., Satpathy, K. K., Prasad, M. V. R., Chakraborty, S., and Bhattacharya, B. D. (2007). Distribution and possible source of trace elements in the sediment cores of a tropical macrotidal estuary and their ecotoxicological significance, Environment International, 33 (3): 346356.

Chen, C. W., Kao, C. M., Chen, C. F., and Dong, C. D. (2007). Distribution and Accumulation of Heavy Metals in Sediments of Kaoshiung Harbor, Taiwan, Chemosphere 66: 1431-1440.

Chi, K. H., Chang, M. B., and Kao, S. J. (2007). Historical trends of PCDD/Fs and dioxin-like PCBs in sediments buried in a reservoir in Northern Taiwan. Chemosphere, 68(9), 1733–


Cuong, D.T., Bayen, S., Wurl, O., Subramanian, K., Wong, K.K.S., Sivasothi, N., and Obbard, J.P. (2005). Heavy metal contamination in mangrove habitats of Singapore, Marine Pollution Bulletin 50: 1713–1744

Davies, O.A., and Tawari, C.C., (2010).Season and tide effects on sediment characteristics of trans-okpoka creek, upper bonny Estuary, Nigeria. Agric. Biol. J. N. Am. 1 (2), 89.

De Gieter, M. and Baeyens, W. (2005). Arsenic in fish: implications for human health. Reviews in food and nutrition toxicity, CRC Press, Boca Raton, 4: 57-83.

De Wolf, H., and Rashid, R. (2008). Heavy metal accumulation in Littoraria scabraalong polluted and pristine mangrove areas of Tanzania, Environmental Pollution, 152: 636-643.

De Wolf, H., Ulomi, S.A., Backeljau, T., Pratap, H.B., and Blust, R. (2001). Heavy metal levels in the sediments of four Dar es Salaam mangroves Accumulation in, and effect on the morphology of the periwinkle, Littoraria scabra (Mollusca: Gastropoda), Environment International 26: 243-249.

Defew, L. H., Mair J.M., Guzman, H. M (2005). An assessment of metal contamination in mangrove sediments and leaves from Punta Mala Bay, Pacific Panama, Marine Pollution Bulletin 50: 547–552.

Dell’Anno, A., Mei, M. L., Ianni, C., and Danovaro, R. (2003). Impact of bioavailable heavy metals on bacterial activities in coastal marine sediments, World Journal of Microbiology & Biotechnology19: 93–100.

EPA: Environmental Protection Agency of United States, (2001). Methods for Collection, Storage and Manipulation of Sediments for Chemical and Toxicological Analyses. Technical Manual, Office of Water (4305), EPA-823-B-01-002, U.S. Environmental Protection Agency, Washington, DC 20460.

Essien, J. P., Antai, S. P., and Olajire, A. A. (2009). Distribution, Seasonal Variations and Ecotoxicological Significance of Heavy Metals in

Sediments of Cross River Estuary Mangrove Swamp, Water Air Soil Pollut 197: 91-105.

Guzzella, L., Roscioli, C., Viganò, L., Saha, M., Sarkar, S. K., and Bhattacharya, A. (2005). Evaluation of the concentration of HCH, DDT, HCB, PCB and PAH in the sediments along the lower stretch of Hugli estuary, West Bengal, northeast India. Environment international, 31(4), 523–34.


Holmer, M. (2003). Mangroves of Southeast Asia in: Black K. D. & Shimmield G. B., (Eds.) Biogeochemistry of Marine Systems. Blackwell Publishing Ltd, CRC Press

Kamaruzzaman B.Y., Ong, M.C., Noor Azhar, M.S., Shahbudin, S., and Jalal K.C.A. (2008). Geochemistry of Sediment in the Major Estuarine Mangrove Forest of Terengganu Region, Malaysia, Am. J. Applied Sci., 5 (12):1707-1712.

Kamau, J.N. (2002). Heavy Metal Distribution and Enrichment at Port-Reitz Creek, Mombasa, Western Indian Ocean J. Mar. Sci. 1 (1): 65-70.

Kruitwagen G, Pratap, H. B., Covaci, A., Wendelaar, B. S. E. (2008). Status of pollution in mangrove ecosystems along the coast of Tanzania, Marine Pollution Bulletin 56: 1022–1042.

Kruitwagen, G., Hecht, T., Pratap, H.B., Wendelaar B. S.E., (2006). Changes in morphology and growth of the mudskipper (Periophthalmus argentilineatus) associated with coastal pollution. Marine Biology 149, 201–211.DOI 10.1007/s00227-005-0178-z

Kumar, K. S., Sajwan, K. S., Richardson, J. P., and Kannan, K. (2008). Contamination profiles of heavy metals, organochlorine pesticides, polycyclic aromatic hydrocarbons and alkylphenols in sediment and oyster collected from marsh/estuarine Savannah GA, USA. Marine pollution bulletin, 56(1), 136–49.


Lee, S.-J., Kim, J. -H., Chang, Y.-S., and Moon, M. H. (2006). Characterization of polychlorinated dibenzo-p-dioxins and dibenzofurans in different particle size fractions of marine sediments. Environmental pollution (Barking, Essex : 1987), 144(2), 554–61.


Li X, Wai, O. W. H., Li, Y.S., Coles, B.J., Ramsey, M.H., and Thornton, I. (2000). Heavy metal distribution in sediment profiles of the Pearl River estuary, South China, Applied Geochemistry, 15 (5): 567-581.

MacFarlane, G.R., and Burchett, M.D. (1999). Zinc distribution and excretion in the leaves of the grey mangrove, Avicennia marina (Forsk.) Vierh, Environmental and Experimental Botany 41: 167–175.

MacFarlane, G.R., and Burchett, M.D. (2001). Photosynthetic Pigments and Peroxidase Activity as Indicators of Heavy metal Stress in the Grey mangrove, Avicennia marina (Forsk.), Marine Pollution Bulletin, 42 (2): 233-240.

Machiwa, J.F. (1992). Anthropogenic pollution in the Dar es Salaam harbour area, Tanzania. Marine Pollution Bulletin 24: 562–567.

Machiwa, J.F. (2000). Heavy metals and organic pollutants in sediments of Dar es Salaam harbour prior to dredging in 1999. Tanz. J. Sc.26: 29–46.

Mangion, P., (2011). Biogeochemical Consequences of Sewage Discharge on Mangrove Environments. PhD Thesis, VUB, Belgium

Marchand, C., Lallier Verges, E., Baltzer, F., Alberic, P., Cossa, D., and Baillif, P. (2006). Heavy metals distribution in mangrove sediments along the mobile coastline of French Guiana, Marine Chemistry, 98 (1): 1-17.

Mlay, A.P., Wagner, G.M., and Mgaya, Y.D. (unpublished). A comparative study of the ecology of four sandy/muddy shores in the Dar es

Salaam area. Accessed on 23th August 2012 at



Moon, H.-B., Choi, M., Choi, H.-G., Ok, G., and Kannan, K. (2009). Historical trends of PCDDs, PCDFs, dioxin-like PCBs and nonylphenols in dated sediment cores from a semi-enclosed bay in Korea: tracking the sources. Chemosphere, 75(5), 565–71. http://dx.doi.org/doi:10.1016/j.chemosphere.2009.01.064

Mremi, S. D., and Machiwa, J. F. (2003). Heavy metal contamination of mangrove sediments and the associated biota in Dar es Salaam, Tanzania. Tanz. J. Sc. 29: 61–76.

Mtanga, A,, and Machiwa, J. (2007). Assessment of Heavy Metal Pollution in Sediment and Polychaete Worms from the Mzinga Creek and Ras Dege Mangrove Ecosystems, Dar es Salaam, Tanzania, Western Indian Ocean J. Mar. Sci. 6, (2): 125–135.

Müller, J. F., Haynes, D., McLachlan, M., Böhme, F., Will, S., Shaw, G. R., Mortimer, M., et al. (1999). PCDDs, PCDFs, PCBs and HCB in marine and estuarine sediments from Queensland, Australia. Chemosphere,

(10), 1707–21. Retrieved from


Nobi, E.P., Dilipan, E., Thangaradjou, T., Sivakumar, K., and Kannan, L. (2010). Geochemical and geo-statistical assessment of heavy metal concentration in the sediments of different coastal ecosystems of Andaman Islands, India, Estuarine, Coastal and Shelf Science 87: 253– 264.

Pan, J., Yang, Y., Geng, C., Yeung, L. W. Y., Cao, X., and Dai, T. (2010). Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans in marine and lacustrine sediments from the Shandong Peninsula, China. Journal of hazardous materials, 176(1-3),

–9. http://dx.doi.org/doi:10.1016/j.jhazmat.2009.11.024

Praveena, S.M., Aris, A.Z., and Radojevic, M. (2010). Heavy Metals Dyanamics and Source in Intertidal Mangrove Sediment of Sabah, Borneo Island, EnvironmentAsia 3: 79-83.

PUMPSEA: Peri-urban mangrove forests as filters and potential phytoremediators, of domestic sewage in East Africa (2007). Distribution and fate of heavy metals and indicator pathogens in sewage exposed mangroves, Specific Targeted Research Project Report for Project No. INCO – CT2004 – 510863.

Rumisha, C., Elskens, M., Leermarkers, M., and Kochzius, M, (2012). Trace metal pollution and its influence on the community structure of soft bottom molluscs in intertidal areas of the Dar es Salaam coast, Tanzania Mar. Pollut. Bull., doi: 10.1016/j.marpolbul.2011.12.025

Tam, N.F.Y., and Wong, Y.S. (2000). Spatial variation of heavy metals in surface sediments of Hong Kong mangrove swamps, Environmental Pollution 110: 195-205.

Taylor, M., Ravilious, C., Green, E.P., (2002). Mangrove of East Africa. Biodiversity Series, No. 13, Vol. 12, UNEP World Conservation Monitoring Centre, 26 pp.

Tranchina, L, Basile, S., Brai, M., Caruso, A., Cosentino, C., and Miccichè, S. (2008). Distribution of Heavy Metals in Marine Sedimentsof Palermo Gulf (Sicily, Italy), Water Air Soil Pollut. 191: 245–256.

URT: United Republic of Tanzania, 2013. Population and Housing Census: 2012 Population Distribution by Administrative Areas. National Bureau of Statistics, Dar es Salaam, 264 pp

Van Camp, M., Mjemah, I. C., Al Farrah, N., and Walraevens, K. (2013). Modelling approaches and strategies for data-scarce aquifers: example of the Dar es Salaam aquifer in Tanzania, Hydrogeology Journal 21: 341–356

Zhao, L., Hou, H., Zhou, Y., Xue, N., Li, H., and Li, F. (2010). Distribution and ecological risk of polychlorinated biphenyls and organochlorine pesticides in surficial sediments from Haihe River and Haihe Estuary Area, China. Chemosphere, 78(10), 1285–93.http://dx.doi.org/doi: