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721.
Variation of CH4, CO2, and O2 concentrations in layers of different depths in semi-aerobic and anaerobic landfills was analyzed over a period of 5 years. The results showed that most of the municipal solid waste became basically stable after 5 years of landfill disposal. In the upper and middle layer, the concentration of CH4 in the semi-aerobic landfill was significantly lower than that in the anaerobic landfill in different landfill periods, while in the lower layer, there was little difference in the CH4 concentration between the semi-aerobic and anaerobic landfills. The average concentration of CH4 and CO2 in the anaerobic landfill was always higher than that in the semi-aerobic landfill, while the O2 concentration showed an opposite variation in different landfill periods. This was related to the aerobic reaction of landfill waste around the perforated pipe in the semi-aerobic landfill, which inhibited effective landfill gas generation. 相似文献
722.
化学品环境管理实践中,化学品危害特性和暴露评估相关数据涉及的化学品所有者的商业保密信息(CBI)是管理部门和企业重点关注的焦点之一.通过信息的公布,可以让公众了解化学品的有毒有害特性,提前防范其环境和健康风险,实现管理目标,但同时也可能影响化学品企业的商业利益、竞争地位和技术优势,损害企业的利益.美国和欧盟的化学品管理法规均对CBI提出了规定和要求,其管理实践对完善中国化学品环境管理中保密信息的管理具有积极的借鉴意义. 相似文献
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726.
北京市郊污灌区镉、铜在小麦中的富集特征 总被引:1,自引:0,他引:1
为探讨污灌农田重金属Cd、Cu在小麦中的迁移富集特征及对人类健康的安全性影响,选取北京城郊污灌区17块代表性小麦(Triticum aestivum)样地,运用BCR顺序提取法和高分辨电感耦合等离子体质谱仪(HR-ICP-MS)测定了土壤中Cd、Cu不同化学形态质量比和土壤及小麦根、茎、颖壳、籽粒中消解态全量.结果表明,污灌土壤中Cd、Cu质量比均值分别为0.25mg·kg-1和26.67 mg·kg-1,高于北京土壤元素背景值,已出现积累现象.小麦植株各组织中中Cd质量比从大到小为:根(210.09 μg·kg-1)、茎(100.19 μg·kg-1)、颖壳(60.71μg·kg-1)、籽粒(38.33 μg·kg-1).植株地上部分Cd质量比的加权平均值为52.62 μg·kg-1.Cu质量比从大到小为:根(9.47mg·kg-1)、籽粒(6.03mg·kg-1)、茎(3.53 mg·kg-1)、颖壳(2.94mg·kg-1).植株地上部分Cu质量比的加权平均值为5.30mg·kg-1.Cd、Cu富集系数(BCF)分别为0.38和0.27,转移系数(TI)分别为0.25和0.69.土壤中Cd酸提取态(生物有效态)比例和风险评价(RAC)值显著高于Cu.小麦Cd和Cu的有效性系数(BEC)均值分别为0.18和0.28,表明Cu向地上部分转移能力强于Cd,Cu容易被小麦籽粒吸收;小麦籽粒中Cd、Cu最大质量比分别为0.125mg·kg-1和15.48 mg·kg-1,高于食品中污染物限量标准值25%和50%,应对食品安全给予更多关注.从保证粮食安全性角度出发,建议选择种植有效性系数较低的作物品种(如玉米、豆类),以减少重金属向食物链的迁移. 相似文献
727.
针对三峡库区工业源污染排放量大,对库区水生态环境安全危害大的特点,以库区湖北段工业源为研究对象,采用实际监测和企业申报监测数据方式,辅以排污系数计算方法,统计分析了1995-2007年工业废水量和主要污染物COD的排放量,并采用灰色-马尔柯夫链模型预测2008-2020年的污染负荷.结果表明,自2005年以后,工业废水的排放量呈现逐渐下降的趋势,在2007年达到1 857.13万t,2008年以后逐渐增加.COD的排放量总体呈逐渐下降的趋势,只是在2001年出现上升,到2007年底COD的排放量为611.21 t.随着工业源污染物全防全控的加强,预计工业污染负荷会逐步减少. 相似文献
728.
Xue Song Wang Guang Chao Zhu Shu Jun Wang Wen Ya Wan Ye Bin Tan 《Environmental monitoring and assessment》2011,177(1-4):263-272
The concentrations and chemical partitioning of heavy metals (Co, Cr, Ni, Zn, Cu, and Pb) in the marine near-shore sediment cores were investigated. Typically, the mean concentrations from Core B sediment samples were 98.6, 21.1, 47.0, 46.4, 107.6, and 31.9 mg kg???1 for Cr, Co, Ni, Cu, Zn, and Pb, respectively. The heavy metal concentrations were normalized to commonly used reference elements Al, Li, Sc, and total organic carbon. Based on Pearson coefficients, Li was found to be a good normalizer for Co (r?= 0.974), Cr (r?= 0.967), Ni (r?= 0.898), and Zn (r?= 0.929) in 80 sediment samples from three sampling sites. However, the correlation coefficients between Li and Cu, and Li and Pb were relatively low. Multivariate statistic approaches (Principal Component Analysis and Cluster Analysis) were adopted for data treatment, allowing the identification of two main factors controlling the heavy metal variability in the sediments. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. The results showed that the residual, Fe/Mn oxides and Organic/sulfide fractions were dominant geochemical phases in the enriched sections, indicating low bioavailability of heavy metals in sediments. 相似文献
729.
Nitrogen contamination is a serious concern to sustainable environmental management, and one important source of nitrogen contaminant is due to wastewater treatment using onsite sewage treatment and disposal systems (OSTDS, a.k.a., septic systems). This paper presents a study in which numerical modeling is used to support sustainable decision-making and management of nitrogen contamination by utilizing a recently developed GIS-based software, VZMOD, a Vadose Zone MODel for simulating nitrogen transformation and transport in vadose zone between drainfield of septic systems and water table. VZMOD is based on a physical model of unsaturated flow and nitrogen transformation and transport, and the model is solved numerically using the finite element methods. This is the major difference between VZMOD and other GIS-based software of nitrogen modeling. Using GIS techniques, VZMOD considers spatial variability of a number of hydrogeologic parameters such as hydraulic conductivity and porosity. A unique feature of VZMOD is that VZMOD addresses spatial variability of water table by using VZMOD together with ArcNLET, an ArcGIS-based software developed to simulate groundwater flow and nitrate load from septic systems to surface water bodies. VZMOD is designed to execute in different modes to be compatible with different levels of data availability in various management projects of nitrogen contamination. This paper presents an application of VZMOD at a neighborhood with hundreds of septic systems and heterogeneous hydraulic conductivity, porosity, and water table depth. The modeling results indicate that using septic systems at the considered neighborhood is unsustainable and more management means are necessary. 相似文献
730.
中国耕地资源利用效益研究 总被引:23,自引:0,他引:23
本文认为耕地数量平衡质量下降的错位是当前我国耕地资源利用中存在的一个不可忽视的问题,文章选取了耕地产出效益系数,耕地消耗回报系数、耕地当局染替代系数、耕地利用集约化系数等指标,对我国现有耕地利用效益进行了定量分析,在此基础上,从观念更新,技术进步,财政投资、产权制度优化等角度,提出提高我国耕地资源利用效益的对策,以级解我国人地矛盾的压力。 相似文献