Fractionation and mobility of cadmium and zinc in urban vegetable gardens of Kano, Northern Nigeria

Abdu, N. and Agbenin, J.O. and Buerkert, A. (2012) Fractionation and mobility of cadmium and zinc in urban vegetable gardens of Kano, Northern Nigeria. Environmental Monitoring and Assessment, 184 (4). pp. 2057-2066.

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Metal fractionation provides information on mobility and stability of various metal species which can be used to evaluate the movement of such metals in soils. The effect of wastewater irrigation on the fractions, spatial distribution, and mobility of cadmium (Cd) and zinc (Zn) was investigated in five urban gardens in Kano, Nigeria. Concentration of total Zn in the surface soils (0–20 cm) ranged from 121 to 207 mg kg − 1 while Cd concentration was 0.3–2.0 mg kg − 1. Speciation of both heavy metals into seven operationally defined fractions indicated that the most reactive forms extracted with ammonium nitrate and ammonium acetate, also considered as the bioavailable fractions, accounted for 29–42% of total Cd and 22–54% of total Zn, respectively. The weakly bound fractions of Cd and Zn reached up to 50% of the total Cd and Zn concentrations in the soils. Such high proportions of labile Cd and Zn fractions are indicative of anthropogenic origins, arising from the application of wastewater for irrigation and municipal biosolids for soil fertility improvement. Thus, given the predominance of sandy soil textures, high concentrations of labile Cd and Zn in these garden soils represent a potential hazard for the redistribution and translocation of these metals into the food chain and aquifer.

Item Type: Article
Additional Information: The authors are grateful to the Volkswagen Stiftung, Hannover, Germany, for supporting this research financially under the UrbanFood project within the collaborative program “Resources, their dynamics, and sustainability-capacity-development in comparative and integrated approaches” (no. I/82 189).
Uncontrolled Keywords: Heavy metals, Metal mobility, Metal speciation, Soil contamination
Author Affiliation: Department of Soil Science, Faculty of Agriculture, Ahmadu Bello University, PMB 1044, Zaria, Nigeria
Subjects: Plant Physiology and Biochemistry > Plant Physiology
Divisions: Other Crops
Depositing User: Mr Balakrishna Garadasu
Date Deposited: 28 May 2013 05:21
Last Modified: 28 May 2013 05:21
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