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971.
对某公路节理岩质边坡的安全稳定性进行分析,并提出支护措施。通过FLAC3D建立计算模型,采用强度折减法计算安全系数,得到边坡在未支护情况下的安全系数为0.67,处于不稳定状态。采用全长注浆锚杆进行支护。建立正交试验,以安全系数和工程造价为目标,以锚杆的长度和倾角为因素,得到6 m,2 m,20°的参数优化方案。计算表明,边坡支护后安全系数为1.29,处于稳定状态。同时,得到边坡在开挖扰动和锚杆支护情况下,各个部位的静态位移和动态位移响应,表明:锚杆支护有效地限制了位移的发展,有利于边坡稳定。 相似文献
972.
973.
Ningombam Linthoingambi Devi Ishwar Chandra Yadav Q. I. Shihua Surendra Singh S. L. Belagali 《Environmental monitoring and assessment》2011,177(1-4):23-33
Pulp and paper mills generate varieties of pollutants depending upon type of the pulping process being used. This paper presents the characteristics of wastewater from South India Paper Mill, Karnataka, India which is using recycled waste paper as a raw material. The raw wastewater consists of 80?C90 mg L???1 suspended solid and 1,010?C1,015 mg L???1 dissolved solid. However, pH varied from 5.5?C6.8. The biochemical oxygen demand and chemical oxygen demand ranged from 200?C210 and 1,120?C1,160 mg L???1, respectively. Aerobic treatment of raw effluent attribute to significant reduction in suspended solid (range between 25 to 30 mg L???1) and total dissolved solid (range between 360 to 390 mg L???1). However, pH, temperature, and electrical conductivity were found superior after treatment. Copper, cadmium, iron, lead, nickel, and zinc were found in less quantity in raw effluent and were almost completely removed after treatment. The dendrogram of the effluent quality parameters clearly indicate that South India Paper Mill does not meet Minimal National Standard set by central Pollution Control Board to discharge in agricultural field. 相似文献
974.
Tu C Ma LQ Zhang W Cai Y Harris WG 《Environmental pollution (Barking, Essex : 1987)》2003,124(2):223-230
Arsenic speciation is important not only for understanding the mechanisms of arsenic accumulation and detoxification by hyperaccumulators, but also for designing disposal options of arsenic-rich biomass. The primary objective of this research was to understand the speciation and leachability of arsenic in the fronds of Chinese brake (Pteris vittata L.), an arsenic hyperaccumulator, with an emphasis on the implications for arsenic-rich biomass disposal. Chinese brake was grown for 18 weeks in a soil spiked with 50 mg As kg(-1) as arsenate (AsO4(3-)), arsenite (AsO3(3-)), dimethylarsinic acid (DMA), or methylarsonic acid (MMA). Plant samples were extracted with methanol/water (1:1) and arsenic speciation was performed using high performance liquid chromatography coupled with atomic fluorescence spectrometry. The impacts of air-drying on arsenic species and leachability in the fronds were examined in the laboratory. After 18 weeks, water-soluble arsenic in soil was mainly present as arsenate with little detectable organic species or arsenite regardless of arsenic species added to the soil. However, arsenic in the fronds was primarily present as inorganic arsenite with an average of 94%. Arsenite re-oxidation occurred in the old fronds and the excised dried tissues. Arsenic species in the fronds were slightly influenced by arsenic forms added to the soil. Air-drying of the fronds resulted in leaching of substantial amounts of arsenic. These findings can be of significance when looking at disposal options of arsenic-rich biomass from the point of view of secondary contamination. 相似文献
975.
976.
Small hydropower (SHP) is promoted as a pro-poor renewable energy source that does not have the negative social impacts of large dams. This article challenges these claims, using data from a household survey in China’s upper Red River Basin. We find that SHP can fragment river systems in ways that reduce irrigation water availability, provoke changes to agricultural practices, and negatively impact river health. These social impacts of river fragmentation mainly occur in villages situated between a plant’s intake and outflow. The frequency of plant water diversions due to continued generation in the dry season significantly predicts all social impacts; installed capacity of the plant and the quality of the village’s irrigation infrastructure predict some impacts. Villages with strong local governance can negotiate with the plant to temporarily halt generation when irrigation water is needed, lessening social impacts. Our findings reveal that SHP plants are not as benign as they are made out to be; they must be built and managed according to community needs. 相似文献
977.
改性污泥活性炭对水中镉离子的吸附性能 总被引:3,自引:0,他引:3
以城市污水处理厂的剩余污泥为原料,氯化锌为活化剂制备污泥活性炭,对一部分污泥活性炭用6.0 mol/L的硝酸进行改性,并研究了未改性和改性的污泥活性炭对Cd2+的吸附行为的影响。结果表明,在pH为5.0、Cd2+初始浓度为100 mg/L、吸附剂投加量为2.0 g/L、反应温度为25℃时,未改性的污泥活性炭吸附容量为8.45 mg/g,硝酸改性的污泥活性炭吸附容量达到了23.35 mg/g。改性和未改性的污泥活性炭对Cd2+都有较好的吸附容量,硝酸改性大幅度提高了污泥活性炭对Cd2+的吸附性能。常温下改性污泥活性炭对Cd2+的吸附符合Langmuir吸附等温式。 相似文献
978.
电渗析法处理低浓度乙酸废液的研究 总被引:7,自引:0,他引:7
用电渗析法处理配制的乙酸质量分类为2.5%左右的乙酸水溶液,浓缩液乙酸质量分数达到20%,稀相出水乙酸质量分数至0.02%;对影响处理过程的因素进行了探讨。 相似文献
979.
980.
典型农业活动区土壤重金属污染特征及生态风险评价 总被引:7,自引:0,他引:7
联合野外采样和室内分析,以典型农田土壤为研究对象,分析土壤中重金属Cr、Ni、Cu、Zn、Cd、Pb、As和Hg的含量及污染特征,并采用单因子污染指数法、内梅罗污染指数法及潜在生态危害指数法,对农田土壤进行生态风险评价,同时利用主成分因子分析法,提取出3主因子,分析土壤重金属可能来源。结果表明,研究区农田土壤各重金属含量均高于背景值,表层污染程度高于底层;各重金属单因子污染指数对应污染等级均为清洁,内梅罗污染指数为0.46,污染等级为安全。潜在生态风险评估结果显示,研究区土壤重金属污染的潜在生态风险危害程度为中等,各重金属的潜在生态危害程度依次为Cd> Hg> As> Cu> Pb> Ni> Cr> Zn。主成分因子分析显示,研究区土壤中Hg、As和Cr主要由工业污染源贡献,土壤中Cd、Pb的污染主要来源于不合理的农业生产活动和居民生活,Ni、Zn和Cu与自然成土过程密切相关。综合评价表明,尽管研究区农田土壤目前重金属污染情况较轻,未达到警戒水平,但由于城市化的发展及长期现代化农业耕作活动造成农田土壤重金属的富集,因此,增强农田土壤安全性生产管理、严控土壤污染源与推行标准农业生产是十分必要的。 相似文献