散射光下铁(III)-丙酮酸盐配合物还原铬(VI)的研究

研究了在散射光下铁(III)-丙酮酸盐配合物对铬(V I)的光还原反应;考察了溶液pH、铁(III)、丙酮酸钠、铬(V I)浓度对反应的影响;分析了铬(V I)光还原反应的动力学。实验结果表明:铁(III)-丙酮酸盐配合物体系能在较弱的散射光下还原铬(V I)。在铬(V I)浓度为19.2μm o l/L、铁(III)浓度为10.0μm o l/L、丙酮酸钠浓度为240μm o l/L、pH为3.0、光照240m in的条件下,铬(V I)的还原率达到99.7%。从表观动力学方程的反应级数看,铁(III)的级数(0.83)最高,铁(III)浓度是影响铬(V I)光还原反应速率的主要因素,铁(II)是铬(V I)光还原的主要还原剂。     

Short-duration hydrothermal fermentation of food waste: preparation of soil conditioner for amending organic-matter-impoverished arable soils

Environmental Science and Pollution Research - Soil conditioners can be used to compensate for the insufficient soil nutrition and organic matter (OM) of arable soils. However, the traditional...     

Toxicity of urban highway runoff in Shanghai to Zebrafish (Danio rerio) embryos and luminous bacteria (Vibrio qinghaiensis.Q67)

Pollution from urban highway runoff has been identified as one of the major causes of the deterioration of receiving water quality. The purpose of this study is to assess the toxicity of urban storm water samples in Shanghai using the zebrafish (Danio rerio) embryo test and the bacterial luminescence (Vibrio qinghaiensis) assay. The toxicity of highway runoff from seventeen storm events was investigated in both grab and composite samples. Zebrafish embryos were exposed to the runoff samples and development parameters including lethality, spontaneous movements in 20 s, heart beat rate, hatching rate, and abnormality of zebrafish embryos were observed after 24, 48, 72, and 96 h of exposure. Inhibition rates of luminescence intensity were also recorded. The results showed that in the zebrafish embryo toxicity tests, both grab and composite samples increased the lethality, reduced the percentage with spontaneous movements and heart beats, inhibited the hatching of embryos, and induced morphological abnormalities. In the Vibrio qinghaiensis toxicity test, all the grab samples inhibited the luminescence, while some of the composite samples promoted it, which indicated that different types of toxicants might have been affecting the species. The multivariate statistics analysis indicated that heavy metal (zinc, manganese, and copper) and PAHs might mainly contribute to the toxicity of runoff samples.     

Evaluation of combined developmental neurological toxicity of di (n-butyl) phthalates and lead using immature mice

Environmental Science and Pollution Research - In this study, the immature mice were taken to assess the potential neurological toxicity of lead (Pb) and di (n-butyl) phthalates (DBP) combination...     

Mercury uptake by Paspalum distichum L. in relation to the mercury distribution pattern in rhizosphere soil

Environmental Science and Pollution Research - Paspalum distichum L. was tested to evaluate their phytoremediation capacity for Hg contaminated soil through analyzing the dissipation of Hg in soil...     

Salinity and nutrient modulate soil bacterial communities in the coastal wetland of the Yellow River Delta,China

The Yellow River Delta is the largest and youngest estuarine and coastal wetland in China and is experiencing the most active interactions of seawater and freshwater in the world. Bacteria played multifaceted influence on soil biogeochemical processes, and it was necessary to investigate the intermodulation between the soil factors and bacterial communities. Soil samples were collected at sites with different salinity degree, vegetations, and interference. The sequences of bacilli were tested using 16S rRNA sequencing method and operational taxonomic units were classified with 97% similarity. The soil was highly salinized and oligotrophic, and the wetland was nitrogen-restricted. Redundancy analysis suggested that factors related with seawater erosion were principal to drive the changes of soil bacterial communities and then the nutrient level and human disturbance. A broader implication was that, in the early succession stages of the coastal ecosystem, seawater erosion was the key driver of the variations of marine oligotrophic bacterial communities, while the increasing nutrient availability may enhance in the abundance of the riverine copiotrophs in the late stages. This study provided new insights on the characteristics of soil bacterial communities in estuarine and coastal wetlands.

     

广西都安县耕地土壤重金属污染风险评价

为全面了解广西都安瑶族自治县耕地土壤重金属污染特征和生态风险状况,通过实地调查采样及土壤重金属含量分析,利用单因子指数、内梅罗综合指数、Hakanson潜在生态危害指数对都安县耕地土壤中Cd、As、Ni、Zn、Cr、Sb、Cu、Pb这8种重金属进行污染和生态风险评价.结果表明,都安县耕地土壤重金属总体污染严重,74.6%的耕地土壤点位超标,Cd、As、Ni、Zn、Cr、Sb、Cu、Pb的超标率依次为70.6%、42.9%、34.9%、19.8%、19.6%、2.94%、1.59%、0.79%,其中Cd和As超标率远远超过全国和广西水平,是都安县主要的污染元素.都安县耕地土壤总体呈现"中度"生态风险,其中Cd对生态风险贡献率达到88%;九渡乡东南部和保安乡与东庙乡结合部存在高生态风险.都安县耕地土壤重金属污染来自两个主要污染源,其中刁江流域两岸受污灌耕地土壤中As、Sb污染可能主要来源于刁江上游的矿业活动.     

Microbial reduction of uranium (VI) by Bacillus sp. dwc-2: A macroscopic and spectroscopic study

The microbial reduction of U(VI) by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES). Our studies indicated that approximately 16.0% of U(VI) at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter (NOM) played an important role in enhancing the bioreduction of U(VI) by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states (U(VI) and U(IV)) after bioreduction, which was subsequently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy (HRTEM) analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wall. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.     

Effect of oxide nanoparticles on the morphology and fluidity of phospholipid membranes and the role of hydrogen bonds

Engineered oxide nanoparticles (NPs) are widely applied in insulators, catalyzers, paints, cosmetic products, textiles and semiconductors. Their attachment on cell membrane may lead to cytotoxicity. The effects of Al₂O₃, Fe₂O₃, SiO₂, TiO₂ and ZnO NPs on membrane integrity and fluidity were studied using giant or small unilamellar vesicles in this study. Al₂O₃ and SiO₂ NPs disrupted the oppositely charged membrane, indicating the important role of electrostatic attraction. However, Fe₂O₃, TiO₂ and ZnO NPs did not cause serious membrane disruption as Al₂O₃ and SiO₂ NPs. Membrane fluidity was evaluated by the generalized polarity (GP) values of Laurdan fluorescent emission. SiO₂ NPs induce the membrane gelation of both positively and negatively charged membrane. Al₂O₃ and ZnO NPs induced the gelation of the oppositely charged membrane, but did not cause obvious membrane gelation to the like charged membrane. The phospholipid molecular structural changes after NP exposure were analyzed by Fourier transform infrared (FT-IR) spectroscopy. FT-IR spectra revealed the hydrogen bond formation between NPs and the carbonyl/phosphate groups of phospholipids. Al₂O₃ and SiO₂ NPs showed strongest evidence of hydrogen bonding on their FT-IR spectra. It was consistent with the microscopic observation and fluorescent data that Al₂O₃ and SiO₂ NPs caused more serious membrane disruption and gelation. This study on membrane damage provides further knowledge on the cytotoxicity of nanomaterials and the safety of NP application.     

湖北省PM2.5与PM10比值分析及PM2.5时空分布特征研究

基于2012年-2014年湖北省大气污染物监测数据,通过数据反演方法,得到湖北省17个城市的PM2.5年均浓度.利用ArcGIS绘制出各城市不同年份的颗粒物浓度空间分布图,并对其进行分析.结果表明,2012年-2014年间,湖北省17个城市PM2.5与PM10年均浓度比值为0.66,PM2.5年均浓度超出国家二级标准,整体呈现上升趋势.城市方面,在多数城市PM2.5与PM10浓度上升的同时,仅武汉、黄冈和天门3个城市颗粒物浓度2014年较2013年有所下降,且武汉市PM2.5浓度下降率达12.8%,表明武汉市近两年来采取的政策措施具有较好的可行性和有效性.