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971.
采用渔网及土工布挂片双层材料以及填充的水花生构建了生态围隔,对藻类进行拦截,降低取水口藻类密度,同时通过水花生的吸收和拦截,以及土工布挂片形成的附着生物群落的降解和吸收作用,降低颗粒态以及溶解态营养盐,达到取水口水质的改善效果.生态工程实施后,取水口内悬浮颗粒物显著降低了29.8%,同时透明度提高了27.5%.对藻类的拦截效果研究表明,围隔对叶绿素a的去除率为23.0%,对总藻类数量的去除率为20.7%.通过对围隔内外蓝藻数量在藻类数量的比例分析,生态围隔对蓝藻的去除率高于总藻类的去除率,说明了对于藻类拦截的效果具有一定的选择性.对营养盐的改善效果主要体现在颗粒态物质上,其中颗粒态氮磷的去除率分别为48.4%和31.3%. 相似文献
972.
石化行业废水种类多样、毒性较大,给排水系统的设计会直接影响石化项目建成后周边地表及地下水环境质量。设计文件的环保审查是环境监理的重要依据之一,其中,相关的设计图纸对下一步建设工作具有指导作用,是所有施工单位的施工依据。以某石化行业为例,对给排水系统设计文件的收集进行了分析,并根据设计图纸环保审查中存在的问题,对环境监理如何提高在设计会审中的作用,设计阶段如何对设计图纸进行审查以及审查的重点内容等进行了阐述。 相似文献
973.
974.
975.
976.
通过泥石流灾害模拟模型与灾害损失率计算方法了解旅游景区的损失状况,研究自然灾害对旅游景区的破坏作用。旅游景区洪灾模拟模型由分流模型与汇流模型构成,根据泥石流多相流成分中固液两相分离原则构建泥石流分流模型;引用DEM数据得到泥石流流域栅格的汇流方向,根据经验模型计算汇流用时,采用八方向方法获取河道信息,基于这些数据构建泥石流模拟的汇流模型,采用ArcGis软件实时呈现该模型的泥石流灾害模拟效果;结合ArcGis软件显示的灾情数据,采用洪灾损失率计算方法获取旅游景区自然灾害损失率。实验结果表明,该模型计算旅游景区建筑损失率误差均小于5%,在有效模拟泥石流灾害的同时,可准确描述自然灾害对旅游景区的破坏作用。 相似文献
977.
G. Shi Z. Chen C. Bi J. Teng S. Xu 《Environmental pollution (Barking, Essex : 1987)》2010,158(3):694-703
A set of toxic metals, i.e. As, Hg, Pb, Cd, Cu, Zn, Ni and Cr, in urban and suburban SDSs were investigated comparatively in the biggest metropolitan area of China, Shanghai. Results showed that all of the metals except As were accumulated greatly, much higher than background values. Geo-accumulation index indicated that metal contamination in urban SDSs was generally heavier than that in suburban SDSs. Potential ecological risk index demonstrated that overall risks caused by metals were considerable. Cd contributed 52% to the overall risk. Multivariate statistical analysis revealed that in urban SDSs, Zn, Ni, Cd, Pb, Cu and Cr were related to traffic and industry; coal combustion led to elevated levels of Hg; soil parent materials controlled As contents. In suburban SDSs, Pb, Cu, As and Cd largely originated from traffic pollution; Zn, Ni and Cr were associated with industrial contaminants; Hg was mainly from domestic solid waste. 相似文献
978.
Spatial distribution of nonylphenol polyethoxylates (NPEOs) and nonylphenol (NP) was investigated in a field study in Lanzhou Reach of the Yellow River. NPEOs and their metabolites were found in the river, with the maximum dissolved concentrations of 6.38 nmol/L for NPEOs, 0.19 nmol/L for nonylphenol ethoxy acetic acids (NPECs) and 0.79 nmol/L for NP, respectively. The maximum concentrations in the sediment and suspended particle samples were 1.50 and 5.09 nmol/g for NPEOs and NP, respectively. The effects of particles, light and microorganism on the dissipation of NPEOs in the river water were investigated based on lab-scale experiments. When natural particles were removed, 72% and 22% degradation of NPEOs were achieved at 120 h in non-sterile and sterile conditions with light, respectively. Different concentrations of NPECs were also observed in these experiments. When suspended particle matters (SPMs) were present, about 38-50% of NPEOs were sorbed to the particulate phase in only 1 h. As a result, the degradation of NPEOs and production of NPECs were inhibited. However, the combined sorption and degradation in the presence of SPMs resulted in lower dissolved NPEO concentrations than those in the absence of SPMs. Biodegradation was the most important pathway for NPEOs degradation in the river water, while NPECs seemed to be produced through both biological and abiological pathways. 相似文献
979.
Huijing Qian Yanjun Wu Yong Liu Xinhua Xu 《Frontiers of Environmental Science & Engineering》2008,2(1):51-56
The kinetics of Cr(VI) reduction to Cr(III) by metallic iron (Fe0) was studied in batch reactors for a range of reactant concentrations, pH and temperatures. Nearly 86.8% removal efficiency for Cr(VI) was achieved when Fe0 concentration was 6 g/L (using commercial iron powder (< 200 mesh) in 120 min). The reduction of hexavalent chromium took place on the surface of the iron particles following pseudo-first order kinetics. The rate of Cr(VI) reduction increased with increasing Fe0 addition and temperature but inversely with initial pH. The pseudo-first-order rate coefficients (k obs) were determined as 0.0024, 0.010, 0.0268 and 0.062 8 min?1 when iron powder dosages were 2, 6, 10 and 14 g/L at 25°C and pH 5.5, respectively. According to the Arrehenius equation, the apparent activation energy of 26.5 kJ/mol and pre-exponential factor of 3 330 min?1 were obtained at the temperature range of 288–308 K. Different Fe0 types were compared in this study. The reactivity was in the order starch-stabilized Fe0 nanoparticles > Fe0 nanoparticles > Fe0 powder > Fe0 filings. Electrochemical analysis of the reaction process showed that Cr(III) and Fe(III) hydroxides should be the dominant final products. 相似文献
980.
钢铁行业是我国主要的能源消费及CO2排放行业,推动钢铁行业低碳绿色发展已成为实现我国碳达峰、碳中和的重要环节。为此,研究围绕能源结构调整、工艺结构优化、节能减排技术推广和CCUS技术应用4方面,通过设置基础情景、稳定发展情景和强化减排情景3类情景,利用边际减排成本曲线对我国钢铁行业34项减排技术的减排成本和减排潜力进行分析。结果表明:在稳定发展情景下,我国钢铁行业平均减排成本为433元/tCO2,所有技术的总减排成本为2100亿元,总减排潜力为4.9亿t。在各项减排技术中,废铁-电弧炉炼钢具有较高的减排经济效益,其以较低的单位减排成本贡献了钢铁行业近50%的碳减排量。未来,我国应加快推进长流程炼钢向短流程炼钢的发展,推动钢铁行业生产工艺的结构性调整。 相似文献