Crop uptake of heavy metals in response to the environment and agronomic practices on land near mine tailings in the Zambian Copperbelt Province

被引:0
作者
Belinda Kaninga
R. Murray Lark
Benson H. Chishala
Kakoma K. Maseka
Godfrey M. Sakala
Scott D. Young
Andrew Tye
Elliott M. Hamilton
Michael J. Watts
机构
[1] Mount Makulu Central Research Station,Zambia Agriculture Research Institute
[2] University of Zambia,School of Agricultural Sciences
[3] Copperbelt University,Inorganic Geochemistry, Centre for Environmental Geochemistry
[4] British Geological Survey,School of Biosciences
[5] University of Nottingham,undefined
来源
Environmental Geochemistry and Health | 2021年 / 43卷
关键词
Heavy metals; Pumpkin leaves; Maize; Lime; Manure; Mine tailings; Agronomic amendments;
D O I
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学科分类号
摘要
A field experiment was undertaken on farmers’ fields adjacent to a large mine tailings dam in the Zambian mining town of Kitwe. Experimental plots were located close to the tailings (≤ 200 m) or further away (300–400 m) within the demarcated land farmed by the same community. This study evaluated the uptake of Cd, Cu, Ni, Pb and Zn by pumpkin leaves and maize grown in soil amended with lime and manure applied at agronomic rates, and the subsequent risk of dietary exposure to the local community, typical of many similar situations across the Zambian Copperbelt. Treatments, combinations of lime and manure (present or absent), were applied to subplots selected independently and randomly within each main plot, which represented variable geochemistry across this study site as a result of windblown/rain-driven dust from the tailings. Total elemental concentrations in crops were determined by ICP-MS following microwave-assisted acid digestion. Concentrations of Cu and Pb in pumpkin leaves were above the prescribed FAO/WHO safe limits by 60–205% and by 33–133%, respectively, while all five metals were below the limit for maize grain. Concentration of metals in maize grain was not affected by the amendments. However, lime at typical agronomic application rates significantly reduced concentrations of Cd, Cu, Pb and Zn in the pumpkin leaves by 40%, 33%, 19% and 10%, respectively, and for manure Cd reduced by 16%, while Zn increased by 35%. The uptake of metals by crops in locations further from the tailings was greater than closer to the tailings because of greater retention of metals in the soil at higher soil pH closer to the tailings. Crops in season 2 had greater concentrations of Cu, Ni, Pb and Zn than in season 1 due to diminished lime applied only in season 1, in line with common applications on a biannual basis. Maize as the staple crop is safe to grow in this area while pumpkin leaves as a readily available commonly consumed leafy vegetable may present a hazard due to accumulation of Cu and Pb above recommended safe limits.
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页码:3699 / 3713
页数:14
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