Associations between distance lags,groundwater velocities,and detection efficiencies in groundwater monitoring networks

Effects of distance lags between landfills and monitoring wells on contaminant detection capability were quantified in several groundwater velocity settings. Detection efficiency calculations were made with and without imposing a time limit on contaminant travel. In general, longer distance lags yieldedhigher detection efficiencies. However, detection efficienciesdecreased as monitoring wells approached a buffer zone boundaryimposing a maximum permissible contaminant transport distance.Imposing a time limit on contaminant travel substantially reduced detection efficiency in low velocity settings, especiallyat longer distance lags. Time limits were less significant in high velocity settings where contaminants more quickly reachedmonitoring wells. Detection efficiencies also decreased as velocity increased, but decreases were minor once the velocityreached a threshold value.     

利用自养煤矸石砖技术治理铬渣初步研究

本研究通过焙烧试验 ,对利用自养煤矸石砖技术治理铬渣进行了初步研究。结果表明 ,在自养煤矸石砖的焙烧过程中 ,其中炭和自身热量能将铬渣中六价铬还原成 (三价铬 )。本研究确定了该铬渣治理方法工艺简单、成本低、解毒彻底、稳定性强 ,具有广泛的应用前景。     

Leaf area development, dry weight accumulation and solar energy conversion efficiencies of Phaseolus vulgaris L. under different soil moisture levels near Nairobi, Kenya

Leaf area development, dry weight accumulation and solar energy conversion efficiencies of Phaseolus vulgaris L. cv GLP-2 under two soil moisture levels in two contrasting seasons near Nairobi, Kenya were investigated. The experiment confirms that dry weights and yields of Phaseolus vulgaris are limited by a drought induced decrease in leaf area, leading to less radiation interception as a source for assimilation. However, photosynthetic efficiency in Phaseolus vulgaris also appears to decrease and to contribute to these effects. Finally, an even larger decreases of economic efficiency as obtained in the second season, where stress lasted much later into the season, reveals that such a drought also limits considerably the partitioning and translocation of assimilates to the seeds of Phaseolus vulgaris. The efficiencies obtained are in line with the better literature data for other crops.     

Impact of land-use types on nitrate concentration and δN in unconfined groundwater in rural areas of Korea

An understanding of the long-term changes in the nitrate contamination pattern of unconfined groundwater is critical to conservation of drinking water in rural areas supporting mixed land-use activities such as cropping, livestock farming, and residence. To examine the effect of different land-use activities on nitrate contamination, groundwater samples were collected monthly for 3 years (1997–1999) from 12 wells in rural areas with different land-use activities and analyzed for the concentrations and N isotopic ratios (δ¹⁵N) of nitrate. The characteristics of nitrate contamination clearly differed with land-use activities. The percentages of samples that had a nitrate concentration exceeding the national standard for drinking water (10 mg N L⁻¹) were 0, 23, 43, and 67% for the uncontaminated natural area, cropping area, cropping-livestock farming complex area, and residential area, respectively. The range of δ¹⁵N values was between +1.4 and +4.5‰ for groundwater nitrate from the uncontaminated natural area. In the cropping area, the δ¹⁵N values were slightly different with the type of fertilizer applied to fields in the vicinity of the well, and the values ranged between +8.7 and +14.4‰ for the compost-applied area and between +4.5 and +8.5‰ for the area where urea was applied with compost. The δ¹⁵N values of the cropping-livestock farming complex area ranged from +1.0 to +17.7‰, probably resulting from mixed contamination sources (inorganic fertilizer and livestock manure). The well located closest to the livestock feedlot had relatively higher δ¹⁵N values, with a range between +8.7 and +17.6‰. In the residential area, a higher δ¹⁵N (most frequently above +10‰) of nitrate suggested that the major source of contamination was effluent from leaky septic tanks. Our data showed that unconfined groundwater is susceptible to land-use activities above the aquifers, and the impacts of the activities could be more precisely inferred from long-term data on the concentration and δ¹⁵N of nitrate. By determining the impacts, more effective (specific to contamination sources) measures for preventing groundwater quality could be implemented.     

指标计算法在环境经济损益分析中的应用

以上海市江桥和闸北2座生活垃圾焚烧厂建设项目为例,采用指标计算法对这2家在不同选址区的建设项目环境经济损益进行了分析。结果表明：江桥生活垃圾焚烧厂项目具有较好的环境经济效益,其环保年净效益为670．69万元,效费比达到1．10。闸北生活垃圾焚烧厂项目的环保年净效益为－764．48万元,效费比为0．64,说明其环境污染控制方案存在明显的不经济性。江桥生活垃圾焚烧厂已投入建设。指标法为2个项目的环境经济损益分析提供了货币量化。     

纵横复合收尘极板电除尘器特性的研究

电除尘器由于体积大 ,成本高而制约其在企业中应用。根据电流体力学收尘场原理 ,提出一种新型的纵横复合收尘极板电除尘器 ,它把纵向和横向电除尘器有机结合起来。通过正交试验与单因素试验 ,得出这种新型电除尘器的最佳运行参数。它能有效提高单位体积电除尘器收尘极板面积 ,对减小电除尘器体积、改善电除尘器性能具有较大的现实意义     

声波反吹清灰对除尘效率的影响

声波反吹清灰会使除尘效率略有降低，已被实验和统计资料所证实。为减小其对除尘效率的影响，又要达到降低除尘器运行阻力的目的，必须选择合适的鸣喇叭次数。对于较难脱落的粉尘应选较多的鸣喇叭次数，而对较易脱落的粉尘则不需每次清灰都鸣喇叭，仅需偶而启动一次。本文通过实验证明，对本实验所用的除尘系统，每四次反吹清灰后鸣喇叭一次是合适的。     

对壳幔二元混合模型的讨论

壳幔二元混合模计算结果的意义是多解的。对该模型所获得的“壳幔比”,并不象一些研究者所认为并强调的那样具有定量意义。所以,将f_M视为岩浆形成时地幔物质直接参与的质量比是不正确的;实质上,它只能被用来定性地反映岩浆源区岩石的成熟程度。     

试论执行力文化的构建与政府行政效率的提高

首先论述了执行力文化的提出及内涵,随后说明了导致政府行政效率低下的3个原因,由此引出了在政府中倡导构建执行力文化是提高政府效率的有效手段,最后以秦皇岛市为例,说明了在政府中如何构建执行力文化的几个方面内容.     

高邮地磁台加卸载响应比与江苏及邻近地区的地震预测

研究分析了高邮地磁台1980～2001年观测资料的加卸载响应比异常与江苏及邻近地区ML5.0以上地震之间的关系,提出了适用于高邮地磁台的地震分析预报参数,并对其内检预报效能进行了评价。