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631.
基于物元模型的土地整理项目绩效评价方法与案例研究 总被引:8,自引:0,他引:8
随着新公共管理理念的普及和土地整理在我国社会经济发展中重要性的日益显著,对土地整理项目绩效评价理论、方法及实证研究意义重大。针对已有研究的不足,在界定土地整理项目绩效内涵基础上构建了基于“流程逻辑”框架的土地整理项目绩效评价指标体系,结合物元分析法建立了物元评价模型,并以浙江省永康市石柱镇土地整理项目为例,展开了实证研究。结果表明物元评价模型适合用于土地整理项目绩效评价。综合评价显示永康市石柱镇项目总体绩效水平为“较差”,绩效值为0.014 4。单指标评价显示:该项目只有4个指标绩效水平达到“良好及以上”,1个指标处于“一般”,其他的都处于“较差”水平;研究项目区的绩效水平主要受耕地面积增加率、土地利用提高率等9个因素影响。永康市在今后的土地整理项目建设中应该针对这些绩效影响因素采取相应措施,不断改善项目的整体绩效水平 相似文献
632.
基于F-AHP的产业转移后可持续发展评价模型构建与实证研究 总被引:2,自引:0,他引:2
本着系统思想, 运用F AHP法,依据现有相关数据和多位专家意见,从产业自身发展、产业与区域经济发展、产业与区域社会发展、产业与区域资源环境发展4个模块30个指标构建产业转移后可持续发展评价指标体系,建立包含指标间模糊关系矩阵和面向参评产业的模糊评价矩阵的评价模型。通过模型评价了2006~2009年江苏苏北各市转移产业的可持续发展水平和能力。模型结果表明:苏北五市近年来承接的产业已获得较好的生存能力和可持续发展能力,但从可持续发展度的分值来看,苏北各市转移产业的可持续发展水平还不高;相比于传统产业,各市目前转移产业的可持续发展水平普遍较高,但苏北五市承接的产业有较大的同构性。因此,苏北各市下一阶段应优先发展比较优势产业,错位承接转移产业并考虑其可持续发展能力的培育 相似文献
633.
Foliar uptake of airborne lead is one of the pathways for Pb accumulation in plant organs. However, the approximate contributions of airborne Pb to plant organs are still unclear. In the present study, aerosols (nine-stage size-segregated aerosols and total suspended particulates), a wild plant species (Aster subulatus) and the corresponding soils were collected and Pb contents and isotopic ratios in these samples were analyzed. Average concentration of Pb was 96.5 ± 63.5 ng m−3 in total suspended particulates (TSP) and 20.4 ± 5.5 ng m−3 in the fine fractions of size-segregated aerosols (SSA) (<2.1 μm), higher than that in the coarser fractions (>2.1 μm) (6.38 ± 3.71 ng m−3). Enrichment factors show that aerosols and soils suffered from anthropogenic inputs and the fine fractions of the size-segregated aerosols enriched more Pb than the coarse fractions. The order of Pb contents in A. subulatus was roots > leaves > stems. The linear relationship of Pb isotope ratios (206Pb/207Pb and 208Pb/206Pb) among soil, plant and aerosol samples were found. Based on the simple binary Pb isotopic model using the mean 206Pb/207Pb ratios in TSP and in SSA, the approximate contributions of airborne Pb into plant leaves were 72.2% and 65.1%, respectively, suggesting that airborne Pb is the most important source for the Pb accumulation in leaves. So the combination of Pb isotope tracing and the simple binary Pb isotope model can assess the contribution of airborne Pb into plant leaves and may be of interest for risk assessment of the exposure to airborne Pb contamination. 相似文献
634.
van der Ploeg MJ Baveco JM van der Hout A Bakker R Rietjens IM van den Brink NW 《Environmental pollution (Barking, Essex : 1987)》2011,159(1):198-203
Effects of C60 nanoparticles (nominal concentrations 0, 15.4 and 154 mg/kg soil) on mortality, growth and reproduction of Lumbricus rubellus earthworms were assessed. C60 exposure had a significant effect on cocoon production, juvenile growth rate and mortality. These endpoints were used to model effects on the population level. This demonstrated reduced population growth rate with increasing C60 concentrations. Furthermore, a shift in stage structure was shown for C60 exposed populations, i.e. a larger proportion of juveniles. This result implies that the lower juvenile growth rate due to exposure to C60 resulted in a larger proportion of juveniles, despite increased mortality among juveniles. Overall, this study indicates that C60 exposure may seriously affect earthworm populations. Furthermore, it was demonstrated that juveniles were more sensitive to C60 exposure than adults. 相似文献
635.
Quantification of nitrate leaching from German forest ecosystems by use of a process oriented biogeochemical model 总被引:1,自引:0,他引:1
Kiese R Heinzeller C Werner C Wochele S Grote R Butterbach-Bahl K 《Environmental pollution (Barking, Essex : 1987)》2011,159(11):3204-3214
Simulations with the process oriented Forest-DNDC model showed reasonable to good agreement with observations of soil water contents of different soil layers, annual amounts of seepage water and approximated rates of nitrate leaching at 79 sites across Germany. Following site evaluation, Forest-DNDC was coupled to a GIS to assess nitrate leaching from German forest ecosystems for the year 2000. At national scale leaching rates varied in a range of 0–>80 kg NO3–N ha−1 yr−1 (mean 5.5 kg NO3–N ha−1 yr−1). A comparison of regional simulations with the results of a nitrate inventory study for Bavaria showed that measured and simulated percentages for different nitrate leaching classes (0–5 kg N ha−1 yr−1:66% vs. 74%, 5–15 kg N ha−1 yr−1:20% vs. 20%, >15 kg N ha−1 yr−1:14% vs. 6%) were in good agreement. Mean nitrate concentrations in seepage water ranged between 0 and 23 mg NO3–N l−1. 相似文献
636.
637.
大宝山矿区水体和沉积物中重金属的污染评价 总被引:2,自引:0,他引:2
分别于丰水期和枯水期对广东省大宝山矿区铁龙拦泥坝至凉桥河段水体中溶解态的重金属进行了调查,应用EPA推荐的健康风险评价模型发现,水体中非致癌物通过饮水途径所导致平均个人年风险排列顺序是Cu〉Pb〉Zn,最大值的平均个人年风险在丰水期和枯水期的平均值分别是2.14×10-7 a-1和4.13×10-7 a-1,小于国际防辐射委员会(ICRP)推荐的最大可接受平均个人年风险5.0×10-5a-1。致癌物Cd的平均个人年风险在丰水期和枯水期的平均值分别是3.52×10-4 a-1和4.53×10-4 a-1,大于ICRP推荐的最大可接受值,同时也大于非致癌物3~4个数量级。另外,通过对枯水期沉积物的重金属总量分析,发现凉桥槽对坑支流受水体pH的影响,导致其沉积物重金属的浓度最高。根据Long和Macdonald利用生物效应数据库法建立的沉积物质量基准,发现除冷水泾外,其他采样点的平均效应中值指数(mERMQ)值都大于1.5,可见沉积物中的重金属会对当地底栖生物产生毒害作用。 相似文献
638.
Fernández-Macho J 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2947-2953
Underlying levels of atmospheric pollutants, assumed to be governed by smoothing mechanisms due to atmospheric dispersion, can be estimated from global emissions source databases on greenhouse gases and ozone-depleting compounds. However, spatial data may be contaminated with noise or even missing or zero-valued at many locations. Therefore, a problem that arises is how to extract the underlying smooth levels. This paper sets out a structural spatial model that assumes data evolve across a global grid constrained by second-order smoothing restrictions. The frequency-domain approach is particularly suitable for global datasets, reduces the computational burden associated with two-dimensional models and avoids cumbersome zero-inflated skewed distributions. Confidence intervals of the underlying levels are also obtained. An application to the estimation of global levels of atmospheric pollutants from anthropogenic emissions illustrates the technique which may also be useful in the analysis of other environmental datasets of similar characteristics. 相似文献
639.
宁波市大气可吸入颗粒物PM1o和PM2.5的源解析研究 总被引:2,自引:0,他引:2
在宁波市布设4个代表性点位,于2010年春季、夏季和冬季进行大气PM10和PM2.s的采样,同时采集了多种颗粒物源样品,建立了PM10、PM2.5和源样品的化学成分谱.采用化学质量平衡模型(CMB)对宁波市PM10、PM2.5进行源解析.结果表明,城市扬尘、煤烟尘、机动车尾气尘是宁波市PM10、PM2.5的3大污染源,... 相似文献
640.
为探索浅水湖泊水动力扰动作用对底泥再悬浮影响的规律,在室内矩形水槽内模拟了各种水动力条件下太湖底泥的起动规律,得到了太湖底泥在3种不同起动标准下的起动流速,通过考察上覆水中悬浮物浓度的变化,建立了底泥沉积物再悬浮通量与水体流速的定量化关系。结果表明:太湖底泥在个别动、少量动、普遍动3种标准下的起动流速分别为15、30和40 cm/s,且底泥沉积物再悬浮通量与流速呈现线性正相关关系,再悬浮通量随流速增大而增大,且相关性较好。将该试验结果应用于太湖的水量水质数学模型中,并和太湖实测资料进行了对比,取得了比较满意的效果。该模拟装置能够在室内可控条件下较好地反映太湖沉积物再悬浮特征,对太湖的富营养化治理具有重要意义。 相似文献