钼矿区选矿场周边农田土壤重金属污染状况分析与评价

以葫芦岛市钼矿区为例,分析钼矿区选矿场周边农田土壤重金属污染状况并对其污染现况进行评价.选择选矿场周边受污染农田土壤样本20个,采用HNO3-HF-HClO4混酸对土壤样品进行处理,运用等离子体发射光谱仪(ICP-AES)测定土壤样品中Mo、Pb、As、Hg、Cr、Cd、Zn、Cu、Ni的全量并进行评价.结果表明:钼矿区选矿厂周边农田土壤重金属Nemerow综合指数8.46,综合评价结果为该区土壤已受严重污染;主要污染物为Cd、Cr、Hg、Zn,并伴有Ni、Cu污染;选矿厂周边农田土壤重金属元素全量中化学形态分布为:残余态＞有机结合态＞氧化结合态＞酸可提取态;农田酸可提取态、氧化结合态、有机结合态三种形态的重金属可能来源于不同外援污染;重金属Hg的有效态比例较大,可能会影响农作物的正常生长;钼矿区选矿区周边农田土壤重金属污染除来源于污染地下水的浇灌,还来源于大气降尘、汽车尾气以及矿物运输过程中矿石的遗落.     

有机废水制取氢气及COD的去除

针对当前能源紧缺以及有机废水治理和回收再利用的需求,采用驯化的河底污泥发酵模拟有机废水,研究了不同有机废水制取氢气和去除有机物的效果.结果表明:在相同条件下,糖源质量浓度均为1.67 g·L-1、废水体积为300 mL、pH=5.5、θ=40℃时,糖源为葡萄糖、蔗糖和淀粉的三种有机废水总产氢气量分别是309.36 mL,318.18 mL,8.20 mL,含蔗糖的废水总产氢气量最高.含蔗糖和葡萄糖的废水COD去除率分别是78.00%和76.92%,而含淀粉的废水COD去除率仅为55%.此外,废水产氢规律与从污泥里筛选出的产氢菌生长曲线有密切的关系.厌氧发酵产氢是一个复杂的过程,它受底物种类、底物浓度、pH值和温度等因素的影响.用驯化的污泥来发酵含糖浓度较高的有机废水,不仅可以收集到大量的生物质能氢气,而且一定程度上缓解了有机废水污染环境的问题.     

黄土高原地区水资源承载力动态变化及灰色拓扑预测——以山西、陕西、宁夏、甘肃四省为例

研究水资源承载力对促进区域水资源的合理开发和保证经济可持续发展具有十分重要的作用.文章采用模糊综合评价方法,以水资源利用率、降水量、人均占有水量和生态用水量作为评价因素,首次对黄土高原水资源承载力进行了大尺度综合评价,并建立灰色拓扑预测模型对其动态变化进行预测,在此基础上提出了黄土高原水资源可持续利用对策.结果表明:黄土高原四省水资源承载力在1994-2004年间总体上呈缓慢上升趋势,水资源开发潜力呈微弱增大趋势;但值得注意的是,黄土高原水资源开发已有一定规模,其水环境仍十分脆弱,需要进一步作好节水和水资源的保护工作.     

长期单施NK肥条件下几种典型土壤磷的演化

为探讨我国典型土壤长期单施氮钾肥对土壤全磷和Olsen-P磷的影响,研究了不同气候条件、不同耕作制度下,7种典型土壤类型长期定位试验单施氮钾肥下土壤全磷和Olsen-P变化及其影响因素.结果表明,在长期单施氮钾肥条件下,除杭州水稻土全磷含量稳定在1.0g·kg-1左右外,其余6种耕作土壤全磷含量和土壤Olsen-P均呈显著下降趋势,全磷含量下降幅度在13.6%～44.9%之间;土壤Olsen-P下降速率比全磷高几倍,Olsen-P下降有一定阈值,这一阈值大约为5 mg·kg-1.土壤全磷含量与土壤Olsen-P含量呈极显著直线相关关系.因此,长期单施氮钾肥在很大程度上减少了土壤磷素养分库.     

城市生活垃圾渗透系数测试研究

采用常水头测渗实验,对不同压实密度和水力梯度下的新鲜垃圾与陈垃圾的渗透系数进行测试,根据达西定律求得渗透系数值。由于垃圾的不均匀性、小颗粒的运动和大孔隙沟道流的形成和改变,实验初始阶段渗透系数值先增大至峰值,然后缓慢降低直至趋于稳定。实验稳定后,新鲜垃圾压实密度为0.75~0.95 t/m3时,渗透系数值约为1.26E-03~1.43E-03 cm/s。陈垃圾在压实密度分别为1.2和1.4 t/m3时,渗透系数为8.29E-04和1.35E-04 cm/s。     

Recycling of the hyperaccumulator Brassica juncea L.: synthesis of carbon nanotube-Cu/ZnO nanocomposites

The methods of synthesizing carbon nanotube (CNTs)-Cu/ZnO nanocomposites using a Cu hyperaccumulator (Brassica juncea L.) constitute a new insight into the recycling of hyperaccumulators and provide a new route for the further development of green nanostructure syntheses. In this paper, CNTs-Cu/ZnO nanocomposites have been synthesized using B. juncea plants as the sources of C, Cu, and Zn. The synthesized CNTs-Cu/ZnO nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectra (EDS). The synthesized CNTs were characterized further by selected area diffraction (SAD) patterns and Raman spectroscopy. The results demonstrated that the structure of individual CNTs was middle-hollow, with an outer diameter of about 80 nm. The synthesized CNTs were not at all crystalline and there were a few defects in the walls. The outer diameter of CNTs-Cu/ZnO nanocomposites was 110 nm. The diameters of Cu/ZnO nanoparticles were 29.5/32.7 nm, respectively. Cu/ZnO nanoparticles that had grown onto the CNT surface were nonuniform and agglomerated. The Cu/ZnO nanoparticles were pure.     

Enhanced removal of humic acid from micro-polluted source water in a surface discharge plasma system coupled with activated carbon

Surface discharge plasma (SDP) combined with activated carbon (AC) was employed to eliminate dissolved organic matter from micro-polluted source water, with humic acid (HA) as the model pollutant. Synergistic effect on HA removal was observed in the SDP-AC system; HA removal efficiency reached 60.9% within 5-min treatment in the SDP-AC system with 5.0 g AC addition, whereas 16.7 and 17.4% of HA were removed in sole SDP system and AC adsorption, respectively. Scanning electron microscope and Boehm titration analysis showed that chemical reactions between active species and functional groups of AC occurred. The existence of isopropanol or benzoquinone exhibited inhibitive effects on HA removal in the SDP system, while these inhibitive effects were weakened in the SDP-AC system. The influences of AC on ozone equivalent concentration and H₂O₂ concentration were evaluated, and there were approximately 39 and 20% decline in ozone equivalent concentration and H₂O₂ concentration within 6-min treatment in the SDP-AC system, respectively, compared with those in the sole SDP system. Dissolved organic carbon, specific ultraviolet absorbance, and UV absorption ratios analysis demonstrated that the SDP treatment destroyed the chromophoric groups, double bonds, and aromatic structure of HA molecules, and these destructive actions were strengthened by AC.     

集中式饮用水源地风险管理及应急监测研究——以靖江市为例

饮用水安全是关系民生的一个重要问题,作为城市饮用水重要供给区的地表水源地,其安全问题直接影响一个城市的正常运行。水源地的风险规划,就要从发现水污染事件、组织人员设备、现场处置、信息发布及后勤保障等方面全部有明确规定,形成一套较完善的水污染突发事件应急监测体系,本文以靖江市集中式饮用水源地风险管理为例,探讨如何将水源地保护工作规范化,防患于未然,一旦发生污染事故时,能指导监测人员立即采取有效措施。     

厌氧发酵产氢的研究进展

厌氧发酵产氢具有很多优越性,发展潜力巨大,具有高效、节能、成本低等优点.全文介绍了国内外发酵产氢的研究情况,厌氧发酵产氢的影响因素,并提出了厌氧发酵产氢的发展趋势.     

基于AHP的炼化设备管理模糊综合评价模型研究

依据层次分析法(AHP)理论,建立设备管理多层次评价指标,结合各指标重要性确定权重,建立适用于炼化企业的模糊综合评价模型,并以某炼化企业为例,使用该模型对企业设备管理进行定性与定量评估,进行了管理薄弱项的确认及改进措施的制定.