The influence of atmospheric Hg on Hg contaminations in rice and paddy soil in the Xunyang Hg mining district,China

To date, the Xunyang mercury(Hg) mining district is the only ongoing large-scale Hg mining district in China. To understand the influence of Hg contamination mode from the Hg mining and smelting activities, 27 sampling sites in the Xunyang Hg mining district were chosen in this study. Total gaseous mercury(TGM) in ambient air was measured using a Lumex-RA915 automatic Hg analyzer in2011. Rice samples and soil samples from rhizosphere were collected systematically and simultaneously. Total Hg(THg) and methylmercury(Me Hg) concentrations in rice grain and soil samples and Hg speciation with modified sequential selective extractions were measured. The local environment was seriously polluted with Hg. The TGM(302 ± 376 ng·m-3, ranging from 24 to 2220 ng·m^(-3)) in the local ambient air, THg(28 ± 30 mg·kg^(-1), ranging from 0.31 to 121 mg·kg^(-1)) and Me Hg(2.3 ± 1.9 lg·kg^(-1),ranging from 0.24 to 8.9 lg·kg^(-1)) in soil samples were at the sample level with Hg contaminated area. The THg concentration(26 ± 16 lg·kg^(-1)ranging from 4.5 to 71 lg·kg^(-1)) in most of the rice grain samples clearly exceeds the threshold level(20 lg·kg^(-1)) in the Chinese national guidelines for cereals(NY 861-2004). The inorganic mercury(IHg)(9.1 ± 5.6 lg·kg^(-1), ranging from 1.2 to 24 lg·kg^(-1)) and Me Hg(14 ± 9.8 lg·kg^(-1), ranging from 2.1 to 59 lg·kg^(-1))concentration in rice grain samples were at the same level with Hg contaminated area. The main species of Hg in paddy soils reveal strong complex Hg and residue Hg. According to the correlation analysis, a Hg pollution mode from local Hg mining and smelting was hypothesized, including Hg emission, transportation, methylation, and uptake process.

Influence of litter decomposition on iron and manganese in the sediments of wetlands for acid mine drainage treatments

Plant litter will influence the bioavailability of heavy metals in sediments of wetlands used to treat acid mine drainage. To investigate the effect of plant litter on sediments in wetlands and define the comprehensive and continuous role of plant litter, different mass ratios(0%,5%, 20%) of litter were added into the sediments to study the influence of litter decomposition on the overlying water and sediments. The changes in pH, EC, Eh, Fe, and Mn of the overlying water and the organic matter in the sediments and the forms of Fe and Mn after 1, 7, 14, 21, and 28 days of litter decomposition were studied. The results indicated that litter decomposition increased the pH, EC, and reduced Eh of the overlying water. Litter decomposition promoted the release of Fe and Mn from the sediments into the overlying water and with the continuous decomposition of litter, the concentration of Fe and Mn in the overlying water declined. Litter decomposition increased the content of the organic matter in the sediment, and the forms of Fe and Mn indicated that litter decomposition could significantly affect the transformation of the forms of Fe and Mn.Reducible Fe was the main form in the sediments. Litter decomposition promoted the transformation of reducible Fe, the main form found in the sediments, intoexchangeable and oxidizable Fe, but had no effect on residual form. Exchangeable Mn was the main form in the sediments, and litter decomposition accelerated the transformation of reducible Mn, most commonly found in the sediments, into oxidizable Mn and had little influence on the exchangeable and residual forms.

Effects of a proline solution cover on the geochemical and mineralogical characteristics of high-sulfur coal gangue

Batch experiments tively evaluate the inhibition were conducted to compara- effects and mechanisms of a low-concentration （1%） proline solution cover on the release of pollutants from high-sulfur coal gangue. High- sulfur coal gangue was continuously immersed in a proline solution and in deionized water （as a control treatment） for 540 days. The results showed that the coal gangue in the control treatment was oxidized and generated leachate with poor water qualities, i.e., the leachate exhibited lower pH values, higher redox potential values, higher pollutant concentrations （804^2-, Fe, Mn, Cu, and Zn）, and high levels of acidophilic sulfur-oxidizing bacteria. However, compared to the control treatment, the addition of the proline solution （1%） significantly improved the water quality of the leachate by significantly reducing the Eh values, the pollutant concentrations （804^2-, Fe^2＋, Fe, Mn, Cu, and Zn）, and the activity of acidophilic sulfur-oxidiz- ing bacteria and by significantly increasing the pH value to neutral. The proline treatment significantly inhibited the oxidation of coal gangue and the release of pollutants, mainly by inhibiting the activity of acidophilic sulfur-ox- idizing bacteria and by altering the heavy metal fractions and the mineralogical characteristics. Therefore, in engi- neering practice, workers should consider using an envi- ronmental friendly aqueous proline solution cover to achieve the in-situ control of pollutant releases from coal gangue dumps.

MicroRNAs and cancer

MicroRNAs (miRNAs) belong to a class of noncoding, regulatory RNAs that are involved in oncogenesis and show remarkable tissue specificity.miRNAs are approximately 22 nt non-coding RNAs, which regulate gene expression in a sequence-specific manner via translational inhibition or messenger RNA (mRNA) degradation, thus affecting various cellular processes.Since the discovery of their fundamental mechanisms of action, the field of miRNAs has opened a new era in the understanding of small noncoding RNAs.Recent evidence has shown that miRNA controls cell growth, apoptosis, and differentiation.Cancer is a complex genetic disease caused by abnormalities in gene structure and expression, moreover, miRNA expression correlates with cancers and could have a crucial function in tumor progression.Bioinformatic data indicate that each miRNA can control hundreds of target genes, but identification of the accurate miRNA targets will be crucial to exploit the emerging knowledge of miRNA contribution to cancer process.