ABSTRACT: PurposeSmelting activity produced tons of slags with large quantities of highly toxic metals, resulting in contamination in adjacent
soils and sediments as well. This study investigated the fractionation and sources of metals Pb, Zn, and Cd in polluted soils
and sediments in a region with once prosperous Zn smelting activities in southwestern China. Soils with varying land uses
were of a special concern due to their connection to the food chain. Obtained data would offer a valuable reference to the
development of land-use management strategy in this region.
Materials and methodsIn total, 130 soils and 22 stream sediments were sampled in the studied region. After air-dried and passed through a 2mm
sieve, soils and sediments were subjected to a three-step sequential extraction for the fractionation of Pb, Zn, and Cd. Besides,
66 slags were sampled, and acid-digested for the determination of total Pb, Zn, and Cd. Soils/sediments with extremely high
Pb, Zn, and Cd concentrations were selected for observation and analysis using a scanning electron microscopy equipped with
energy dispersive X-ray spectroscopy. Stable lead and sulphur isotope techniques were applied for source tracing of metals
in soils and sediments. Data were pooled for analysis of variance together with a post-hoc multiple comparison procedure.
Results and discussionHigh concentrations of Pb (∼46,219mgkg−1 with medians of 846mgkg−1 in soil, 7,415mgkg−1 in sediment, and 8,543mgkg−1 in slag), Zn (∼57, 178mgkg−1 with medians of 1,085mgkg−1 in soil, 15,678mgkg−1 in sediment, and 14,548mgkg−1 in slag), and Cd (∼312mgkg−1 with medians of 29.6mgkg−1 in soil, 47.1mgkg−1 in sediment, and 47.9mgkg−1 in slag) were measured. Soils with no cultivation had greater concentrations of Pb (16,686mgkg−1 in median), Zn (13,587mgkg−1 in median), and Cd (44.1mgkg−1 in median) than those with cultivation. Al-normalized enrichment factors for Pb, Zn, and Cd were in 40.6–1,066, 11.6–382,
and 128–647 in sediments, and in 58.0–1,771, 10.1–450, and 88.6–1,035 in soils. Greater Pb/Cd and Zn/Cd ratios in slags (241
and 386 in median) than in soils (uncultivated (187 and 267 in median) > cultivated) or sediments (106 and 260 in median)
were observed, indicating extra atmospheric borne Cd in soils and sediments from smelting dust emission. Pb, Zn, and Cd were
mainly associated with Fe/Mn oxides/hydroxides in soils and sediments, with their mobile fractions varying with land use in
soils that had a close relation to pH (r = −0.569, p < 0.01). In 206Pb/207Pb∼ 208Pb/206Pb diagram, plots of soils and sediments constructed a satisfactory linear model (p < 0.01) with wall rock, coal, and ore samples. Four different domains can be identified in the δ34S–206Pb/207Pb diagram, in which soils and sediments formed a domain with middle δ34S (−2.79 ∼ +10.3‰) and 206Pb/207Pb ratios (1.1823 ∼ 1.1853).
ConclusionsSmelting activities result in great enrichments of Pb, Zn, and Cd in surveyed soils and sediment. Mobile fraction of these
metals was controlled by land use type as well as soil pH, which is informative for land use management to prevent toxic substance
from potentially menacing human health. Bean cultivation and low pH can result in more Cd of mobile fraction in soils, therefore,
alternative cultivation and pH elevation are recommended for the studied region. This would help reduce the remobilization
and uptake of Cd from the polluted soils.
KeywordsChemical fractionation-Isotope tracing-Land use-SEM-EDS
Journal of Soils and Sediments 04/2012; 10(8):1527-1539. · 1.86 Impact Factor
ABSTRACT: Lead, Zn, and Cd in vegetables/crops were investigated in a zinc smelting region in China, and their daily dietary intake by local residents was estimated. It is observed that Pb, Zn, and Cd were in 34.7-91.1, 242-575, and 0.199-2.23 μg g(-1) dry weight in vegetables/crops with their greatest concentrations in leafy vegetable. The daily dietary intake of Pb, Zn, and Cd by adult residents reached 3, 646, 59,295, and 186 μg day, respectively, and lettuce and cabbage together contributed 75% of the Pb, 50% of the Zn, and 70% of the Cd.
Bulletin of Environmental Contamination and Toxicology 08/2011; 87(5):586-90. · 1.02 Impact Factor
ABSTRACT: Plants grown in contaminated areas may accumulate trace metals to a toxic level via their roots and/or leaves. In the present study, we investigated the distribution and sources of Pb and Cd in maize plants (Zea mays L.) grown in a typical zinc smelting impacted area of southwestern China. Results showed that the smelting activities caused significantly elevated concentrations of Pb and Cd in the surrounding soils and maize plants. Pb isotope data revealed that the foliar uptake of atmospheric Pb was the dominant pathway for Pb to the leaf and grain tissues of maize, while Pb in the stalk and root tissues was mainly derived from root uptake. The ratio of Pb to Cd concentrations in the plants indicated that Cd had a different behavior from Pb, with most Cd in the maize plants coming from the soil via root uptake.
Environmental pollution (Barking, Essex: 1987) 01/2009; 157(3):834-9. · 3.43 Impact Factor
ABSTRACT: Historical zinc smelting in Hezhang, southwestern China, has resulted in significant heavy metal contamination of the surrounding ecosystems. The Caohai wetland system, which is an important national nature reserve close to the Hezhang zinc smelting area, was investigated in the present study. Results showed that sediments from the Caohai wetland system have been seriously contaminated by Cd, Pb and Zn with the highest concentrations in the surface sediments being up to 71, 160 and 1,200 microg g(-1), respectively. The heavy metals in the sediments were strongly associated with the organic/sulphide and residual fractions. A more oxidized condition induced by aquatic plants tended to cause the Cd, Pb and Zn bound to the Fe-Mn oxide fraction to become more dominant. Pb isotopic compositions in the sediments indicated that the inventories of Pb in the Caohai wetland sediments were mainly derived from the historical zinc smelting in the Hezhang area, although other anthropogenic sources, such as the gasoline Pb, also made a substantial contribution to the Pb in the sediments. Heavy metal contamination in aquatic plants was also studied and the results indicated that heavy metals accumulated by plants may pose a potential threat to the higher trophic-level organisms, including humans.
Science of The Total Environment 12/2007; 387(1-3):257-68. · 3.29 Impact Factor
ABSTRACT: Total heavy metal (Cd, Cr, Cu, Pb and Zn) concentrations were evaluated in smelting waste, soil, crop and moss samples collected from the Hezhang artisanal zinc smelting areas, Guizhou, China. Soil samples from the cornfield near the smelting sites contained extremely high Cd (5.8-74 mg kg(-1)), Pb (60-14,000 mg kg(-1)) and Zn (260-16,000 mg kg(-1)) concentrations. Elevated heavy metal concentrations were also found in corn plants and total Pb (0.80-1.5 mg kg(-1)) and Cd (0.05-0.76 mg kg(-1)) concentrations in corn grain have totally or partially exceeded the national guidance limits for foodstuff. Thus, the soil-to-crop transfer of heavy metals might pose a potential health risk to the local residents. Similar to the high heavy metal levels in soil and corn, Cd, Cr, Cu, Pb and Zn concentrations in moss samples collected from the smelting sites ranged from 10 to 110, 10 to 55, 26 to 51, 400 to 1200 and 330 to 1100 mg kg(-1), respectively, exhibiting a local spatial pattern of metals deposition from the atmosphere. Based on examination of Zn/Cd and Pb/Cd ratios of the analyzed samples, we have distinguished between the flue gas dust derived and smelting waste derived metals in different environmental compartments.
Environment International 10/2006; 32(7):883-90. · 5.30 Impact Factor
Chinese Journal of Geochemistry 02/2006; 25:41-42.