Search

Gold mine tailing is an important source of arsenic pollution. There are great differences in the arsenic forms of mine tailings formed by different smelting processes. Different arsenic form directly affects its migration and transformation in the environment. Confirming the existing form of arsenic is an important method in the study of repairing arsenic contamination sites. Based on mine tailings generated by two different leaching methods (flotation process and biological oxidation process) for gold, pH meter and Eh meter was used to measure the physical properties of mine tailings (pH, Eh), X-ray Diffraction and X-ray Fluorescent to analyze the mineral phases and main compositions of the mine tailings and Electro-probe Microanalysis to analyze the arsenic existing form. The characterization result shows that the physical properties of flotation mine tailing and biological oxidation mine tailing change with the stacking environment. pH, Eh and pHpzc are almost equal, ie pH≈8.5 and pHpzc≈8.5. The choice of repair method is also restricted because both min tailings belong to the alkaline condition. For example, the electric repair method is only suitable for the acid condition but not for the two main mine tailings. Meanwhile the choice of repair reagent must be alkaline substance and iron oxide (hydroxide). The main mineral compositions of flotation mine tailing are quartz, dolomite and clay minerals and their chemical components are mainly Si and Al. The color of mine tailing is off-white. The arsenic content of this mine tailing is about 754 μg/g, mainly existing in the form of arsenopyrite (FeAsS). However, the main mineral type of biological oxidation mine tailing is gypsum. The main chemical components are Fe, Ca and S with a reddish-brown colour. The arsenic content is about 26350 μg/g. The existing forms of arsenic of this mine tailing are mainly arsenopyrite (FeAsS) and arsenic pentoxide (As2O5). There are many differences in mineral phase, main chemical components and arsenic forms of two kinds of mine tailings because every procedure step of the two-gold leaching processes is different. Therefore, in the in-situ repair work of mine tailings, it should be considered that different methods of gold leaching will influence the piled-up environment of mine tailings and arsenic forms and should be taken into consideration in order to choose a more appropriate, cheap and efficient repair method and choice of reagents.

We aimed to explore changes in basic soil productivity ( BSP) under different fertilization regimes in the Poyang Lake region, Jiangxi Province, China. Soil samples were collected from a long-term fertilization experiment (since 98) that included treatments of no fertilization (CK), chemical fertilization ( NPK), and combined chemical and organic fertilization ( NPKM) . Then, a three-year pot experiment (from 0 to 0) with double rice cropping was conducted with two different fertilization regimes (no fertilization, F0; fertilization, F1) using CK, NPK and NPKM soils. Grain yield and BSP were analyzed among soils with different fertilization regimes to identify the key factors driving changes in BSP. Results showed that grain yields in NPKM soil were higher than in NPK and CK soils regardless of fertilization in the pot experiment. Under the F0 condition, annual grain yields of NPKM soil were 7.7%-.9% and 0.8%-66.7% higher than CK and NPK soils, respectively. The BSP values of CK, NPK and NPKM soils in three years were .8%-5.%, 5.%-6.6% and 59.%-88.%, respectively. NPKM soil had significantly higher BSP than NPK and CK soils. Furthermore, there were significant positive correlations between soil organic matter and BSP as well as between organic carbon balance and BSP. These results suggested that long-term application of chemical and organic fertilizers could improve BSP in the double rice cropping system of the Poyang Lake region. In addition, soil organic matter and organic carbon balance are important factors for improving BSP in this region. [ABSTRACT FROM AUTHOR]

In the present study, the eutrophic level of 30 water samples collected from Lake hongze in August 2014 were analyzed, and the abundance of toxic and non-toxic Microcystis sp., together with their spatial distribution, was investigated by quantitative real-time PCR techniques. The results showed that the average concentrations of total nitrogen and total phosphorus were 1.63 and 0.11 mg x L(-1), respectively. The trophic state index ( TSI) ranged from 58.1 to 73.6, and the water quality was in the state of eutrophication based on TSI. Toxic Microcystis was widely distributed in Lake Hongze, and its abundance varied sharply, from 1. 13 x 10(4) to 3.51 x 10(6) copies x mL(-1), and the abundance of total Microcystis ranged from 1.06 x 10(5) to 1.10 x 10(7) copies x m(-1), meanwhile, the proportion of toxic Microcystis in the total Microcystis ranged from 8.5% to 38.5%, with the average value of 23.6%. Correlation analysis indicated that there was a significant positive correlation among total Mirocystis, toxic Microcystis and the toxic proportion (P < 0.01). The abundance of total and toxic Microcystis was significantly positively correlated to chlorophyll a ( Chl-a) concentrations and TSI (P < 0.01), but was negatively correlated to transparency (SD) (P < 0.01). The ratio of toxic Microcystis to total Microcystis was significantly positively correlated to Chl-a, TN, TP and TSI (P < 0.01), but significantly negatively correlated to the ratio of TN to TP and SD (P < 0.01). Therefore, reducing total nitrogen and phosphorus concentrations could not only lower the eutrophication level of Lake Hongze, but also inhibit the competition advantage of the toxic Microcystis over non-toxic Microcystis.

After "5.12" earthquake, 5 128 reconstruction people from schistosomiasis endemic areas were surveyed for schistosome infection from 2009 to 2001. There were 261 seropositive persons with the positive rate of 5.09%, but there were no persons with positive stool examination. The seropositive rate was higher in reconstruction persons from schistosomiasis endemic areas than that in local residents, therefore, we still should strengthen the active schistosomiasis surveillance of reconstruction people from schistosomiasis endemic areas in order to prevent input of infection source so as to consolidate the achievements of schistosomiasis control.