Jianming Zhu

Distribution of selenium in a mini-landscape of Yutangba, Enshi, Hubei Province, China

Yutangba, where a sudden incidence Se poisoning occurred in 1963, is located in the northern part of Shuanghe Town of Enshi City in the SW of Hubei Province, China. In a small area of 0.01 km2 in Yutangba, the mean concentrations of Se in soil and corn were: soil, 4.06±1.24 μg g−1; total corn, 6.47±4.29 μg g−1; root, 4.36±3.27 μg g−1; stalk, 3.06±2.24 μg g−1; leaf, 9.79±7.62 μg g−1; and seed, 8.07±5.02 μg g−1. the spatial distribution of Se in soil and corn is significantly uneven. Selenium is an active element in the supergene moderate-strong chemical weathering environment. relatively low-Se, median-Se and high-Se subregions can be distinguished according to Se concentrations in soil and corn. Microtopographic features and leaching conditions are the primary factors affecting Se content and distribution in soil and corn. Increased incidence of Se poisoning is likely to occur in the low-Se subregions where Se easily accumulates. Selenium concentrations differ significantly among the organs of corn and decrease in the following order: tassel (male flower), silk (female flower)>leaf>seed>root>stalk>leafy husk of the ear. The Se concentrations in the upper leaves and stalks were greater than in their lower cognates and the outer leafy husk of the ear had a greater Se concentration than the inner leafy husk. This distribution not only indicates that Se is probably an essential element for corn, but also that, under high-Se background and no Se-accumulating indicator plant occurrence, these plant organs with relatively high Se concentrations may be used as a sensitive indicator of Se levels in the environment.

Selenium in Soil Inhibits Mercury Uptake and Translocation in Rice (Oryza sativa L.)

A great number of studies have confirmed that mercury-selenium (Hg-Se) antagonism is a widespread phenomenon in microorganisms, fish, poultry, humans, and other mammals. However, by comparison, little attention has been paid to plants. To investigate the influence of Se on the uptake and translocation of methylHg/inorganic Hg (MeHg/IHg) in the rice-soil system, we determined the levels of Se, IHg, and MeHg in different parts of rice plants (including the root, stem, leaf, husk, and grain (brown rice)) and corresponding soils of root zones collected from a Hg mined area, where Hg and Se co-occur due to historic Hg mining and retorting activities. The results showed that, in general, the Se levels were inversely related to the levels of both IHg and MeHg in the grains. In addition, a consistent reduction in translocation of both IHg and MeHg in the aerial shoots (i.e., the stem, leaf, husk, and grain) with increasing Se levels in the soils was observed. Furthermore, the Se levels were positively correlated with the IHg levels in the soils and the roots. These results suggest that Se may play an important role in limiting the bioaccessibility, absorption, and translocation/bioaccumulation of both IHg and MeHg in the aerial rice plant, which may be related to the formation of an Hg-Se insoluble complex in the rhizospheres and/or roots.

Distributions, sources and pollution status of 17 trace metal/metalloids in the street dust of a heavily industrialized city of central China

A series of representative street dust samples were collected from a heavily industrialized city, Zhuzhou, in central China, with the aim to investigate the spatial distribution and pollution status of 17 trace metal/metalloid elements. Concentrations of twelve elements (Pb, Zn, Cu, Cd, Hg, As, Sb, In, Bi, Tl, Ag and Ga) were distinctly amplified by atmospheric deposition resulting from a large scale Pb/Zn smelter located in the northwest fringe of the city, and followed a declining trend towards the city center. Three metals (W, Mo and Co) were enriched in samples very close to a hard alloy manufacturing plant, while Ni and Cr appeared to derive predominantly from natural sources. Other industries and traffic had neglectable effects on the accumulation of observed elements. Cd, In, Zn, Ag and Pb were the five metal/metalloids with highest pollution levels and the northwestern part of city is especially affected by heavy metal pollution.

Enrichment of Arsenic in Surface Water, Stream Sediments and Soils in Tibet

Groundwater in sedimentary deposits in China, Southern, and Southeast Asia down gradient from the Tibetan plateau contain elevated As concentrations on a regional scale. To ascertain the possibility of source region As enrichment, samples of water (n=86), stream sediment (n=77) and soil (n=73) were collected from the Singe Tsangpo (upstream of the Indus River), Yarlung Tsangpo (upstream of the Brahmaputra River) and other drainage basins in Tibet in June of 2008. The average arsenic concentration in stream waters, sediments and soils was 58±70 μg/L (n=39, range 2-252 μg/L), 42±40 mg/kg (n=37, range 12-227 mg/kg), and 44±27mg/kg (n=28, range 12-84 mg/kg) respectively for the Singe Tsangpo and was 11±17 μg/L (n=30, range 2-83 μg/L), 28±11 mg/kg (n=28, range 2-61 mg/kg), and 30±34 mg/kg (n=21, range 6-173 mg/kg) respectively for the Yarlung Tsangpo. A dug well contained 195 μg/L of As. In addition to elevated As levels in surface and shallow groundwater of Tibet, hot spring and alkaline salt lake waters displayed very high As levels, reaching a maximum value of 5,985 μg/L and 10,626 μg/L As, respectively. The positive correlation between [As] and [Na]+[K] in stream waters indicates that these surface water arsenic enrichments are linked to the hot springs and/or salt lakes. Further, 24% of As in stream sediment is reductively leachable, with bulk As displaying a positive correlation with stream water As, suggesting sorption from stream water. In contrast, the fraction of reductively leachable As is negligible for soils and several rock samples, suggesting that As in them are associated with unweathered minerals. Whether the pronounced As anomaly found in Tibet affects the sedimentary As content in deltas downstream or not requires further study.

Distribution of uranium and thorium in Irtysh River and the upriver wastewater from a rare metal mine impact on it

lag/g) was about 3 times higher than in the control (0.60 lag/g). Conclusions: This study indicated that smelters in a Chinese mercury mine were exposed to extremely high levels of Hg0 vapor, and that miners were estimated to be also exposed to higher levels of MeHg than those in controls. Further study is needed to determine the origin of such the comparatively high hair MeHg concentrations in the exposed group.