长江上游和中下游地区空中水汽资源气候特征对比分析

利用ERA 40再分析资料通过多种统计诊断方法对比分析了长江流域上、中下游空中水汽资源的气候变化特征。研究表明：1958～2001年以来长江流域上游以及中下游地区年平均大气可降水量均呈显著减少趋势,减少率分别为025和026 kg/(m2·10 a);年平均状态下,长江流域上中下游地区均为水汽汇,上游地区年平均收入水汽226×105 kg/s,中下游地区收入124×105 kg/s;1958～2001年长江上游地区的年平均总水汽收入呈显著减少趋势,每10 a减少98×105 kg/s;中下游地区则呈显著增加趋势,每10 a增加115×105 kg/s。夏季水汽收入变化是影响长江流域水汽收支的重要因素,44 a来,长江上游地区水汽总收入减少和该区域夏季南边界上输入的水汽减少密切相关;而中下游地区水汽总收入的增加则主要是由夏季北边界上输出的水汽显著减少所导致;1958～2001年长江流域上、中下游地区水汽收支的变化和该时期夏季风北扩强度的变化有密切关系,其携带的南来水汽扩展变化则是最直接的影响因子。     

Microbial reduction of nitrate in the presence of nanoscale zero-valent iron

Microbial reduction of nitrate in the presence of nanoscale zero-valent iron (NZVI) was evaluated to assess the feasibility of employing NZVI in the biological nitrate treatment. Nitrate was completely reduced within 3 d in a nanoscale Fe(0)-cell reactor, while only 50% of the nitrate was abiotically reduced over 7 d at 25 °C. The removal rate of nitrate in the integrated NZVI-cell system was unaffected by the presence of high amounts of sulfate. Efficient removal of nitrate by Fe(II)-supported anaerobic culture in 14 d indicated that Fe(II), which is produced during anaerobic iron corrosion in the Fe(0)-cell system, might act as an electron donor for nitrate. Unlike abiotic reduction, microbial reduction of nitrate was not significantly affected by low temperature conditions. This study demonstrated the potential applicability of employing NZVI iron as a source of electrons for biological nitrate reduction. Use of NZVI for microbial nitrate reduction can obviate the disadvantages associated with traditional biological denitrification, that relies on the use of organic substrates or explosive hydrogen gas, and maintain the advantages offered by nano-particle technology such as higher surface reactivity and functionality in suspensions.     

Anti-oxidant and hepatoprotective effects of Salvia officinalis essential oil against vanadium-induced oxidative stress and histological changes in the rat liver

Environmental Science and Pollution Research - The present study was designed to evaluate the protective effects of Salvia officinalis essential oil (SOEO) against vanadium-induced hepatotoxicity...     

Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces

This study examines the adsorption isotherms, kinetics and mechanisms of Pb2(+) sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb2(+) in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb2(+) with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca2(+) and PO?3? concentrations during the metal sorption processes. The Pb2(+) sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb(+). The sorption isotherm results indicated that Pb2(+) sorption onto the Langmuir and Freundlich constant q(max) and K( F ) is 9.52 and 8.18 mg g?1, respectively. Sorption kinetics results indicated that Pb2(+) sorption onto WCBP was pseudo-second-order rate constants K? was 1.12 g mg?1 h?1. The main mechanism is adsorption or surface complexation (≡POPb(+): 61.6%), co-precipitation or ion exchange [Ca?(.)?? Pb?(.)?? (PO?)? (OH): 21.4%] and other precipitation [Pb 50 mg L?1 and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb2(+) removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb2(+) indicates its potential as another promising way to remediate Pb2(+)-contaminated media.     

The protective potential of Nitraria retusa on penconazole-induced hepatic injury in adult rats

The protective effect of Nitraria retusa fruit extract against hepatotoxicity induced by penconazole at a dose of 67 mg/kg body weight given intraperitoneally every two days to male Wistar rats was investigated. Penconazole exposure increased malondialdehyde, hydrogen peroxide, and advanced oxidation protein product levels. Hepatic biomarkers as well as enzymatic (catalase, superoxide dismutase and glutathione peroxidase) and nonenzymatic (vitamin C, non-protein thiols and metallothioneins) antioxidant status were also altered. Treatment with N. retusa extract improved all parameters cited above. Liver histological studies confirmed the biochemical parameters. These results provide a scientific basis for the use of N. retusa fruit against hepatotoxicity.     

Physicochemical factors affecting the sensitivity of Ceriodaphnia dubia to copper

The effects of physicochemical conditions, such as pH, water hardness, flow rates and natural organic substances on the sensitivity of Ceriodaphnia dubia to the toxic effects of copper were investigated using static bioassay cups and specially designed flow-through bioassay chambers. We found that C.dubia was very sensitive to pH changes and the total copper LC50 values of C. dubia neonates increased by 15-fold as the pH increased from pH 7 to 10. It was also observed that the LC50 values increased sharply upon increasing the water hardness value to 2.4 meq. In addition, increasing flow rates from zeroto 50 mL hr^-1 also increased its sensitivity to copper, which was possibly due to hydrodynamic stress.The presence of natural organic substances (humic acid and dissolved organic matter) and suspended particles decreased thetoxic effect of copper. This significant decrease in the toxicity of copper in the presence of natural organic materialscan be explained by a reduction in the free ion concentration due to complexation. Furthermore, we observed that the kinetics of copper interactions with natural organic materials are a significant factor in the toxic effect of copper and that the acute LC50 values increased with increasing reaction time betweensolubilized copper and water-borne organics.     

不同干扰下阿拉善荒漠啮齿动物群落格局的变动特征

干扰广泛被认为是影响物种多样性变化的最主要的因素。近年来,物种多样性对干扰的响应是生态学家关注和研究的热点问题之一。2002-2011年,在内蒙古阿拉善荒漠区对人为不同利用（干扰）方式形成的禁牧、轮牧、过牧和开垦4种不同区域中,通过对啮齿动物群落的物种数、物种总捕获率、Shannon-Wiener多样性指数和Pielou均匀性指数等4个变量的时间序列资料的比较,分析了这些变量的年间变动特点及在不同干扰条件下的变动规律,并对不同干扰区各变量的趋势进行分析,探讨啮齿动物群落对不同干扰过程的响应。结果表明：4个变量的最高值均出现在受中等干扰的轮牧区中,物种总捕获率2003年出现了各区的第1个高峰,总捕获率分别为过牧区10.75%、轮牧区19.60%、禁牧区11.20%、开垦区10.55%;2008年出现第2个高峰,4个区物种总捕获率均达到了各区的最高峰,捕获率分别为过牧区29.60%、轮牧区34.15%、禁牧区14.20%、开垦区27.10%。过牧区与轮牧区群落物种总捕获率、Shannon-Wiener指数和Pielou均匀性指数显著相关（p〈0.05）,变动规律相似。过牧区与轮牧区、禁牧区与过牧区、轮牧区与禁牧区之间的物种总捕获率呈极显著正相关（p〈0.01）。过牧区与轮牧区相似度较高（I=0.8568）;过牧区Shannon-Wiener指数表现为有显著的下降趋势（Y=-0.142 lnt＋1.487,F=6.320,p＜0.05）,表明随着过牧时间的积累,对生境的干扰逐步加重,啮齿动物群落的多样性会逐渐降低。     

Process control factors for continuous microbial perchlorate reduction in the presence of zero-valent iron

Process control parameters influencing microbial perchlorate reduction via a flow-through zero-valent iron （ZVI） column reactor were investigated in order to optimize perchlorate removal from water. Mixed perchlorate reducers were obtained from a wastewater treatment plant and inoculated into the reactor without further acclimation. Examined parameters included hydraulic residence time （HRT）, pH, nutrients requirement, and perchlorate reduction kinetics. The minimum HRT for the system was concluded to be 8 hr. The removal efficiency of 10 mg. L-1 influent perchlorate concentration was reduced by 20%-80% without control to the neutral pH （HRT = 8 hr）. Therefore pH was determined to be an important parameter for microbial perchlorate reduction. Furthermore, a viable alternative to pH buffer was discussed. The microbial perchlorate reduction followed the first order kinetics, with a rate constant （K） of 0.761 hr-1. The results from this study will contribute to the implementation of a safe, cost effective, and efficient system for perchlorate reduction to below regulated levels.