Abstract
A speciation study of selected heavy metals in soil and stream sediments around a hospital waste dumpsite was investigated. Sequential extraction procedure was used to fractionate the metals into 4 fractions: Exchangeable and bound to carbonate, oxyhydroxide of Fe and Mn, organic matter and the residual fraction. Speciation analysis of Fe, Mn, Zn, Cu, Cd and Pb in soil revealed that a major portion of the metals were associated with the residual fraction. The exchangeable and carbonate fraction was the most important fraction for Mn(Dry/Wet) and Zn(Dry/Wet) with an average of (27%, 35.6%) Mn and (20.8%, 27.3% ) Zn. Cd, Fe and Cu were associated with the oxyhydroxide of Fe and Mn fraction with an average of (61%, 44.2%) Cd(Dry/Wet), (41%, 21%) Fe(Dry/Wet) and (25.3%, 22.5%) Cu(Dry/Wet). A significant amount of Pb(Dry/Wet) (10.7%, 21.8%) was bound to organic fraction during dry and wet season respectively. In sediments, Mn(Dry/Wet) occurred mainly in exchangeable and carbonate fraction (45.2%, 29.3%), Fe(Dry/Wet) and Cd(Dry/Wet) in the oxyhydroxide of Fe and Mn fraction were (41%, 31.2%) and (26.6%, 93.6%) respectively and the amount of Pb(Dry/Wet) bound to the organic fraction was (86.9%, 27.3%). A significant amount of Cu(Dry/Wet) (20.8%, 29.4%) was bound to the organic fraction and Zn(Dry/Wet) (35.5%, 73%) was retained in the residual fraction. In soil and sediments, Mn was potentially more bioavailable. However, the level of lead in organic matter fraction of soil suggest that it may be remobilized under oxidizing condition, hence, bioavailable. Keywords: Speciation, hospital waste, heavy metal, sediments, soil.
Highlights
Hospital wastes are waste generated within the hospital environment which comprises of pharmaceutical, radioactive, general, sharp, laboratory waste and radioactive materials capable of causing infectious diseases resulting from patient investigation, treatment and diagnosis (Akter, 2000; Abor and Bower, 2008)
Zinc in the sediments was mostly retained in the residual fraction (35.5 and 73%), lesser amount of zinc was found in the organic matter fraction (39 and 9.8%), exchangeable and carbonate fraction (21 and 5.6%) was found in the hydrated iron and manganese oxide fraction (4.5 and 11.8%) during the dry and wet seasons, respectively
Speciation study of metals has been investigated in soil and sediments
Summary
Hospital wastes are waste generated within the hospital environment which comprises of pharmaceutical, radioactive, general, sharp, laboratory waste and radioactive materials capable of causing infectious diseases resulting from patient investigation, treatment and diagnosis (Akter, 2000; Abor and Bower, 2008). Open dumping of hospital waste is an important cause of natural environmental degradation and constitute a health hazard due to the release of heavy metals, chemical solvents, preservatives and infectious substances into the underlying soil and possibility of leachate entering an acquifer or nearby surface water (Akter, 2000). Toxic heavy metals are arsenic, cadmium, chromium, lead and mercury Because of their high degree of toxicity, these five elements rank among the priority metals that are of great public health significance. The bioavailability of heavy metals may be influenced by physical factors such as temperature, phase association, adsorption and sequestration It is affected by chemical factors that influence speciation at thermodynamic equilibrium, complexation kinetics, lipid solubility and water partition coefficients. Biological factors such as species characteristics, trophic interactions and biochemical/ physiological adaptation, play an important role (Verkleji, 1993)
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