HUMAN HEALTH RISKS ASSOCIATED WITH HEAVY METAL-CONTAMINATED SOIL AND FOOD PLANTS IRRIGATED WITH WASTEWATER
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Date
2011
Authors
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Journal ISSN
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Publisher
Department of Environmental Sciences
Abstract
Long-term wastewater irrigation is not only a way of contaminations of soil with heavy
metals (HMs) but also accumulates HMs in food crops. Samples of both soil and
vegetables were collected from wastewater irrigated sites of Peshawar, Pakistan in winter
and summer seasons for analysis of HMs concentrations in them and to investigate the
health risk of associated with HMs contaminated vegetable. The mean concentrations
(mg/kg dry weight) of selected HMs like Cu, Pb, Cd, Ni, Zn, Mn, Cu, Co and Hg in soil
irrigated with wastewater in winter, summer seasons and preference soil were 56.9, 37.01
and 13, 61.28, 62.1 and 10.4, 7.68, 8.9 and 1.2, 100.78, 106.64 and 23, 159.55, 193.4 and
12, 341.33, 387.7 and 14, 40.54, 41.1 and 24, 61.64, 88.2 and 15 and 459.455, 93.1 and
23 mg/kg, respectively
Similarly the mean concentrations (mg/kg dry weight) of studied HMs like Cu, Pb, Cd,
Ni, Zn, Co, Cr, Hg, Mn and Fe in the vegetables grown in wastewater irrigated soil in
winter, summer season and preference soil were 26.8, 24.69 and 13 63.7, 44.7 and 11.45,
8.3, 13.98 and 3, 38.31, 34.and 32.4, 64.1.128.1, and 33, 25, 21.77 and 11, 20.7, 57.45
and 31.68, 421.76, 497.55 and 100.01, 41.1, 32.26 and 17 and 576.85, 632.3 and 300
respectively.
The concentrations of studied HMs were significantly higher in both soil and vegetables
samples collected in summer season than their concentrations in winter’s samples. The
concentrations of Pb, Cd, Ni and Cr exceeded their respective permissible limits set by
WHO/FAO. Transfer factor (TF) values of selected HMs from soil to vegetables and the
target hazard quotients (THQs) to the possible health risks to local population through the
food chain were also calculated. The mean values of root transfer factor (RCFs) ranged
from 0.3-1.4, 0.2-1.4, 0.4-3.7, 0.4-1.1, 0.3-0.6, 0.004-0.18, 1-1.8, 0.12-1.5 and 0.4-1.08
for Pb, Cu, Cd, Ni, Zn, Mn, Co, Cr and Hg, respectively in vegetables of study area..
Similarly, values of shoot transfer (SCFs) for Pb, Cu, Cd, Ni, Zn, Mn, Co, Cr and Hg
ranged from 0.2-1.4, 0.2-4, 0.3-4.7, 0.2-0.8, 0.47-2.46, 0.02-0.45, 0-1.2, 0.34-2.2 and 0.5-
2.01, respectively in the samples of vegetables.