汕头地区农业生态系统中有机氯农药的研究

有机氯农药（Organochlorine Pesticides,OCPs）是一类由人工合成的杀虫广谱、毒性较低、残效期长的化学杀虫剂。本文以汕头市为研究区域,探讨了土壤OCPs的残留现状和特征,并对该区的土壤进行了环境质量评价和初步的生态风险评价。结果表明：（1）汕头地区土壤中OCPs的检出率高达99.13％,OCPs残留量的平均值是113.37 ng·g^-1,主要的OCPs污染物为DDTs和硫丹类;南澳县OCPs残留量平均值最高（174.68 ng·g^-1）,其次为龙湖区,濠江区含量平均值最低（69.24 ng·g^-1）;（2）与国内外一些地区土壤中OCPs的残留量对比,本研究区域土壤中的OCPs处于中等污染残留水平;与美国马里兰州标准、纽约州可容许的土壤浓度标准和我国的土壤环境质量标准相比较,OCPs基本没有超标;（3）本研究地区土壤存在较高的生态风险,OCPs可能对环境造成一定的危害,其中生态风险最高的是DDTs,BHCs的生态风险较低。     

基于栖息地模拟的重口裂腹鱼繁殖期适宜生态流量分析

介绍了栖息地模拟方法原理及步骤,以姜射坝水电站减水段为例,应用栖息地模拟模型PHABSIM计算了重口裂腹鱼繁殖期适宜生境需水量。结果表明,该河段内重口裂腹鱼繁殖期适宜生态流量为40.6m3/s,其与水文学法的结果对比表明,该流量可以满足维持水生生物良好的生存条件的要求。指出当工程河段涉及珍稀鱼类关键生境时,采用栖息地模拟法确定受影响河段的生态需水量,可以更好地保护珍稀鱼类关键生境。研究结果可为已建电站减水河段生态修复工作提供依据,为拟建电站水生生态环境影响评价工作提供借鉴。     

外绝缘用液体硅橡胶老化现象的微观表征

本文针对近年来出现在一些变电站SF6电压、电流互感器的液体硅橡胶绝缘护套出现龟裂老化这一现象,对发生老化的硅橡胶材料进行了性能测试和试验,并利用红外光谱分析、XPS分析、热失重等手段分析了其微观结构和物质组成的变化。研究发现老化后的液体硅橡胶中Si-C、Si-O官能团和Si、C、O元素的相对含量发生了变化,且随着老化程度的增加呈现出较为明显的规律,老化越严重,Si-C键含量越少,C元素的含量越少,O元素含量越多。本文认为,用官能团含量、元素相对含量可以准确地表征液体硅橡胶材料的老化程度。通过对不同老化程度的液体硅橡胶进行的憎水性、耐漏电起痕性能的试验也证实了本文的观点。     

加速溶剂萃取-超高效液相色谱（UPLC）测定土壤中苯并（a）芘

本文优化了加速溶剂萃取-超高效液相色谱测定土壤中苯并（a）芘的方法。样品经加速溶剂提取,逐级减压浓缩,0.25um滤膜过滤净化,超高效液相色谱（UPLC）测定。结果表明,标准溶液苯并（a）芘含量在3.125～lOOug／L范围内,苯并（a）芘的线性呈良好的线性关系,相关系数为0.9999,该方法的检出限和测定下限分别为0.015μg/kg和0.060μg/kg。将该方法用于4个地区土壤样品的测定,苯并（a）芘含量在0.04～6.26ug／kg之间,空白加标回收率为75.2％～96.4％之间,各项指控指标符合检测要求。     

2001-2010年三峡库区（重庆段）相对资源承载力时空格局动态演变研究

运用相对资源承载力理论,并结合库区实际扩展了传统指标体系,改进了权重算法,研究了2001-2010年三峡库区（重庆段）自然资源、经济资源、生活水平的相对承载力与综合承载力的时空动态演变过程.研究表明：①近10年,三峡库区（重庆段）综合承载力偏低,人口严重超载.②随着库区经济社会的快速发展,自然资源承载力严重不足.③库区相对资源承载力空间差异显著.研究结果对把握库区资源承载力变化规律和空间分异特征具有重要意义,同时为三峡库区控制人口数量、调整人口分布,合理有效配置资源提供科学依据.     

Evaluation of the ecological status with benthic indices in the coastal system： the case of Bohai Bay （China）

Based on biologic and environmental materials collected from coastal areas of Bohai Bay （China） in April, 2008, three biotic indices （AZTI＇s Marine Biotic Index （AMBI）, Shannon-Wiener Index and W-statistic） were applied together to evaluate the ecological status of the sampling area. The results showed a clear spatial gradient from a worse ecological status in the near-shore areas （especially around Haihe and Jiyun River Estuaries） to a better status in the offshore areas. While all the three indices could assist decision makers in visualizing spatial changes of organic pollutants in Bohai Bay, two indices, i. e., AMBI and Shannon-Wiener index, were effective in distinguishing sites from Haihe River Estuary, Jiyun River Estuary and other area. However, W-statistic can＇t tell the differences between estuaries and other area. It would be explained that organic pollutants and/or other environ- mental stresses in Bohai Bay were not strong enough to reduce the size ofmacrozoobenthos, which may cause both of the abundance and biomass curves crossed. To our knowledge, this is the first time that several benthic indices were used to assess the benthic ecological status in Bohai Bay, which gave the similar results. Furthermore, there is indication that the ecological status is related to excess input of wastewater along main rivers and outlets. In a word, AMBI, Shannon-Wiener Index and W-statistic could be able to assess the benthic ecological status of Bohai Bay under the organic pollutants pressure.     

Effect of seawater salinity on the synthesis of zeolite from coal fly ash

A novel method for the synthesis of zeolite was developed in this paper. The synthesis was carried out by hydrothermal activation after alkali fusion and coal fly ash （CFA） was used as raw material with seawater of different salinities. Seawater salinity was varied from 32 to 88 for zeolite crystallization during the hydrothermal process. The results show that seawater salinity plays an important role in zeolite synthesis with CFA during hydrothermal treatment. The products were a mixture of NaX zeolite and hydroxysodalite; seawater salinity more strongly affected the crystallization than the type and chemical composition of the zeolites. The yield of CFA transformed into zeolite gradually rose with the increase in salinity, reaching a transformation rate of 48%--62% as the salinity increased from 32 to 88, respectively. The proposed method allows for the efficient disposal of by-products; therefore, the application of seawater in zeolite synthesis presents promising economic and ecological benefits.     

Cation exchange resin supported nanoscale zero-valent iron for removal of phosphorus in rainwater runoff

Self-made cation exchange resin supported nanoscale zero-valent iron （R-nZVI） was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial concentration of 0.72 mg. L-1 phosphorus when the dosage of R-nZVl is 8 g per liter rainwater, while only 26% of phosphorus was removed when using cation exchange resin without supported nanoscale zero-valent iron under the same condition. The adsorption capacity of R-nZVI increased up to 185 times of that of the cation exchange resin at a saturated equilibrium phosphorous concentration of 0.42 mg. L-1. Various techniques were implemented to characterize the R-nZVI and explore the mechanism of its removal of phosphate. Scanning electron microscopy （SEM） indicated that new crystal had been formed on the surface of R-nZVI. The result from inductive coupled plasma （ICP） indicated that 2.1% of nZVI was loaded on the support material. The specific surface area was increased after the load of nanoscale zero-valent iron （nZVI）, according to the measurement of BET-N2 method. The result of specific surface area analysis also proved that phosphorus was removed mainly through chemical adsorption process. X-ray photoelectron spectroscopy （XPS） analysis showed that the new product obtained from chemical reaction between phosphate and iron was ferrous phosphate.     

Novel synthetic approaches and TWC catalytic performance of flower-like Pt/CeO2

A novel Ultrasonic Assisted Membrane Reduction （UAMR）-hydrothermal method was used to prepare flower-like Pt/CeO2 catalysts. The texture, physical/chemical properties, and reducibility of the flower-like Pt/CeO2 catalysts were characterized by X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）, Transmission Electron Microscope （TEM）, N2 adsorption, and hydrogen temperature programmed reduction （HE-TPR） techniques. The catalytic performance of the catalysts for treating automobile emission was studied relative to samples prepared by the conventional wetness impregnation method. The Pt/CeO2 catalysts fabricated by this novel method showed high specific surface area and metal dispersion, excellent three-way catalytic activity, and good thermal stability. The strong interaction between the Pt nanoparticles and CeO2 improved the thermal stability. The Ce4＋ ions were incorporated into the surfactant chains and the Pt nanoparticles were stabilized through an exchange reaction of the surface hydroxyl groups. The SEM results demonstrated that the Pt/CeO2 catalysts had a typical three-dimensional （3D） hierarchical porous struc- ture, which was favorable for surface reaction and enhanced the exposure degree of the Pt nanoparticles. In brief, the flower-like Pt/CeO2 catalysts prepared by UAMR-hydrothermal method exhibited a higher Pt metal dispersion, smaller particle size, better three-way catalytic activity, and improved thermal stability versus conven- tional materials.     

Effects of bicarbonate and cathode potential on hydrogen production in a biocathode electrolysis cell

A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell （MEC）. The strategy for fast biocathode cultivation was demonstrated. An exoelectrogenic reaction was initially extended with an H2-full atmosphere to enrich Ha-utilizing bacteria in a MEC bioanode. This bioanode was then inversely polarized with an applied voltage in a half-cell to enrich the hydrogen-evolving biocathode. The electrocatalytic hydrogen evolution reaction （HER） kinetics of the biocathode MEC could be enhanced by increasing the bicarbonate buffer concentration from 0.05 mol·L-1 to 0.5 mol· L-1 and/or by decreasing the cathode potential from -0.9 V to - 1.3 V vs. a saturated calomel electrode （SCE）. Within the tested potential region in this study, the HER rate of the biocathode MEC was primarily influenced by the microbial catalytic capability. In addition, increasing bicarbonate concentration enhances the electric migration rate of proton carriers. As a consequence, more mass H＋ can be released to accelerate the biocathode-catalyzed HER rate. A hydrogen production rate of 8.44 m3. m 3. d1 with a current density of 951.6 A. m-3 was obtained using the biocathode MEC under a cathode potential of - 1.3 V vs. SCE and 0.4 mol· L-1 bicarbonate. This study provided information on the optimization of hydrogen production in biocathode MEC and expanded the practical applications thereof.