水环境中六溴环十二烷的光降解研究

<span>研究了模拟太阳光和500W紫外灯两种光源下,水中六溴环十二烷(HBCDs)的光降解动力学,同时还研究了紫外光下pH、腐植酸(HA)、Fe(Ⅲ)、过氧化氢(H2O2)和二氧化钛(TiO2)纳米颗粒对HBCDs降解效率的影响.研究表明,在模拟太阳光和紫外光照下,HBCDs的降解速率常数和半衰期分别是7.5&times;10-3h-1、0.11h-1和92h、6.5h.在紫外光下,溶液的初始pH对HBCDs的光降解几乎没有影响.而HA、Fe(Ⅲ)和H2O2对HBCDs的光降解均有一定程度的促进作用,但作用较弱,促进作用由大到小的顺序为HA&gt;Fe(Ⅲ)&gt;H2O2.而TiO2纳米颗粒对HBCDs光降解的催化作用则非常显著.结果表明,直接光解是HBCDs光解的主要途径.在TiO2纳米颗粒的催化下,自然水体中HBCDs可在紫外光照射下快速而有效地去除.&nbsp;</span><span><a id="ChDivSummaryMore" style="display: none"><font color="#002b82">更多</font></a><a id="ChDivSummaryReset" style="display: none"><font color="#002b82">还原</font></a></span><span>The degradation kinetics of HBCDs under simulated sunlight and UV lamp(500 W) were studied.And the effect of initial pH,humic acid(HA),Fe(Ⅲ),peroxide hydrogen(H2O2) and TiO2 nanoparticles on the photolysis of HBCDs in water under UV lamp was also examined.It was found that the rate constant and half-life under simulated sunlight and UV lamp were 7.5&times;10-3 h-1,0.11 h-1,92 h and 6.5 h,respectively.Under UV lamp,the effect of initial solution pH was minimal,and the effect of HA,Fe(Ⅲ) and H2O2 was no</span

Dissolution of Uranium-Bearing Minerals and Mobilization of Uranium by Organic Ligands in a Biologically Reduced Sediment

<p>The stability and mobility of uranium (U) is a concern following its<br />reductive precipitation or immobilization by techniques such as bioremediation at contaminated sites. In this study, the influences of complexing organic ligands such as citrate and ethylenediaminetetraacetate (EDTA) on the mobilization of U were investigated in both batch and column flow systems using a contaminated and bioreduced sediment. Results indicate that both reduced U(IV) and oxidized U(VI) in the sediment can be effectively mobilized with the addition of EDTA or citrate under anaerobic conditions. The dissolution and mobilization of U appear to be correlated to<br />the dissolution of iron (Fe)- or aluminum (Al)-bearing minerals, with EDTA being more effective (with R2&ge;0.89) than citrate (R2 &lt; 0.60) in dissolving these minerals. The column flow experiments confirm that U, Fe, and Al can be mobilized by these ligands under anoxic conditions, although the cumulative amounts of U removal constituted ～0.1% of total U present in this sediment following a limited period of leaching. This study concludes that the presence of complexing organic ligands may pose a long-term concern by slowly dissolving U-bearing minerals and mobilizing U even under a strict anaerobic environment.</p

Spatial distribution, electron microscopy analysis of titanium and its correlation to heavy metals: Occurrence and sources of titanium nanomaterials in surface sediments from Xiamen Bay, China

&nbsp; <p>Titanium nanomaterials are likely to sink into sediments in substantial quantities due to their wide use in a number of applications for decades. To assess the potential environmental consequences, a better understanding is required of the occurrence and sources of titanium (Ti) nanomaterials in sediments. In this research, we provide the first report of the Ti concentrations and the morphology and composition of Ti-based solids in surface sediments from Xiamen Bay, China. Results indicated that the anthropogenic Ti concentrations in the surface sediments from Xiamen Bay reached approximately 2.74 g kg^&minus;1. Ti nanomaterials could be found in sediments with elevated Ti concentrations, which were often aggregated to a few hundred nanometers (&lt;300 nm) and were composed of several spherical particles, less than 50 nm in size, that were made solely of TiO_<em>x</em>. However, Ti particles (approx. 300&ndash;700 nm) could be also found in sediments with lower Ti concentrations, which were presumably components of the natural clay mineral kaolinite. Ti nanomaterials could be easily distributed in sediments associated with elevated levels of organic matter and preferentially attach to those sediments with elevated fine fractions. As a sentinel, or tracer, for other nanomaterials, the field-scale investigation of Ti nanomaterials would contribute to increasing our knowledge on the behavior of engineered nanomaterials in an aquatic environment.</p

Complete genome sequence of a marine roseophage provides evidence into the evolution of gene transfer agents in alphaproteobacteria

Roseophage RDJLF1 is a siphovirus isolated from South China Sea on Roseobacter denitrificans OCh114. Its virion encapsulates 62.7 kb genome that encodes 87 gene products. RDJLF1 shares similar genome organization and gene content with the marine bacteriophage FJL001 and Pseudomonas phages YuA and M6, which are different from those of typical l- or Mu-like phages. Four hallmark genes (ORFs 81 to 84) of RDJLF1 were highly homologous to RcGTA-like genes 12 to 15. The largest gene (ORF 84) was predicted to encode a tail fibre protein that could be involved in host recognition. Extended phylogenetic and comparative genomic analyses based on 77 RcGTA-like element-containing bacterial genomes revealed that RcGTA-like genes 12 to 15 together appear to be a conserved modular element that could also be found in some phage or prophage genomes. Our study suggests that RcGTA-like genes-containing phages and prophages and complete RcGTAs possibly descended from a same prophage ancestor that had diverged and then evolved vertically. The complete genome of RDJL phage 1 provides evidence into the hypothesis that extant RcGTA may be a prophage remnant

人工湿地组合生态工艺对规模化猪场养殖废水的净化效果研究

<dd>研究了表面流、水平潜流和垂直潜流人工湿地以及地下渗滤系统组合生态工艺对模拟和实际猪场养殖废水的净化效果.结果表明,在进水P(COD)=709.2mg&middot;L-1,P(TN)=597.1 mg&middot;L-1,P(NH4+-N)=560.4mg&middot;L-1和P(TP)=42.5mg&middot;L-1的质量浓度条件下组合生态系统对于COD、TN、NH4+-N和TP的去除率分别可以达到87%、95%、97%和95%,其中COD的去除主要在第一级表面流人工湿地,NH4+-N和TN去除主要是在水平潜流和垂直潜流人工湿地,水平潜流和垂直潜流人工湿地对溶解性磷酸盐去除效果明显,地下渗滤起到进一步稳定出水水质的作用.水平潜流和垂直潜流人工湿地的运行结果对比表明,后者对污染物的去除率均高于前者.</dd

Effects of engineered nano-titanium dioxide on pore surface properties and phosphorus adsorption of sediment: Its environmental implications

<p>Understanding the environmental safety and human health implications of engineered nanoparticles (ENPs) is of worldwide importance. As an important ENPs, engineered nano-TiO(2) (Enano-TiO(2)) may have been substantially deposited in aquatic sediments because of its widely uses. Sediment pore surface properties would be thus significantly influenced due to the large surface area of Enano-TiO(2). In this study, Enano-TiO(2) was found to greatly impact on sediment pore surface properties. The attachment of Enano-TiO(2) particles to sediment surfaces enhanced markedly BET specific surface area and t-Plot external specific surface area, and thereby increased sediment phosphorus (P) adsorption maximum (S(max)). Contrarily, the fill of Enano-TiO(2) particles into the micropores of sediments could significantly reduce t-Plot micropore specific surface area, and cause slight decrease in sediment P binding energy (K). Clearly, P sorbed in sediment would be easily released because of the decreasing P binding energy of the sediment with elevated Enano-TiO(2). Enano-TiO(2) would thus cause aggravated endogenous pollution in water if such sediment was re-suspended on disturbance. The results obtained in this study contribute to our increasing knowledge of how to regulate physicochemical behavior of pollutants in sediments under the influences of Enano-TiO(2) and/or similar ENPs.</p

Contamination and source differentiation of Pb in park soils along an urbanerural gradient in Shanghai

Urban soil Pb contamination is a great human health risk. Lead distribution and source in topsoils from 14 parks in Shanghai, China were investigated along an urban-rural gradient. Topsoils were contaminated averagely with 65 mg Pb kg-1, 2.5 times higher than local soil background concentrations. HCl extracts contained more anthropogenic Pb signatures than total sample digests as revealed by the higher 207/206Pb and 208/206Pb ratios in extracts (0.8613 and 2.1085 versus total digests 0.8575 and 2.0959). This suggests a higher sensitivity of HCl-extraction than total digestion in identifying anthropogenic Pb sources. Coal combustion emission was identified as the major anthropogenic Pb source (averagely 47%) while leaded gasoline emission contributed 12% overall. Urbanization effects were observed by total Pb content and anthropogenic Pb contribution. This study suggests that to reduce Pb contamination, Shanghai might have to change its energy composition to clean energy