南京市不同时间尺度温度变化特征

利用南京市1951～2005年的气温资料,研究了南京市不同时间尺度的气温变化特征。结果表明：1951～2005年,南京市温度的年变化呈现上升趋势,年平均最高温度的上升幅度较年平均最低温度高,温度日较差（DTR）的年平均值为下降趋势,1992年可作为近55a南京地区冷暖期的转折点。温度的季节变化也多数呈现上升趋势,四季的平均气温增暖幅度最大是春季,最小的是夏季;四季的平均最高气温与平均最低气温多数都表现为上升的趋势,只有夏季的平均最高温度表现为下降的趋势。因此,近55a南京市在温度总体呈现上升趋势的情况下,夏季有变凉的趋势。四季的DTR的变化中,只有春季为上升趋势,其余季节都是下降的趋势。极端年份的日平均温度变化趋势基本一致,但各年份的DTR变化趋势却不相同。     

基于农业用地和地形约束的陇南山区适宜人口规模估算

陇南山区地形复杂,耕地不足,经济贫困,人口对资源环境的压力较大。研究适度人口容量对于地震灾后重建、缓解贫困以及保护长江上游的生态安全具有重要意义。以人均粮食和经济水平两个指标来估算温饱、宽裕和小康3个水平上的人口承载量,测度人口和农业资源的关系。并基于地形复杂度计算劳动用工及可抚养人口。结果表明:目前陇南10县(区)的人口在温饱生活水平下尚有超载。以小康生活为标准,适宜人口规模约为135万。经营现有的农耕地和林地需要100.81万劳动力,可抚养人口191.54万人,加上城镇人口总人口为231.03万。这个人口规模实现温饱有余而宽裕不足,难达小康目标。"人口-农业用地-劳动力"之间形成了一个怪圈,决定了陇南山区农村实现小康目标的艰巨性和复杂性。为此,陇南山区的灾后重建和区域可持续发展需要创新思路,多方并举。     

Economic assessment of microbial biodiesel production using heterotrophic yeasts

The production of biodiesel using oleaginous microorganisms is investigated as promising alternative to produce a truly sustainable and renewable transportation fuel. While the feasibility of this approach has been shown on the laboratory scale, a commercial scale implementation is to date inhibited due to economic restraints. In order to evaluate the current cost situation and to develop suggestions to reduce production related costs, a simple cost analysis of the proposed microbial oil production process has been carried out. For closed fermentation in large-scale fermenters a break-even price of 2,350 US$ t^–1 for microbial oil was calculated. In the context of a sensitivity analysis it was shown that especially alterations in capital cost can lead to overall cost reductions. Accordingly, an open pond cultivation approach was designed, cutting the cost for equipment almost in half and decreasing the break-even price to 1,723 US$ t^–1. However, these reductions are only feasible when stable biomass and lipid yields can be ensured in open-pond systems, because the sensitivity analysis identified these yield parameters as leading factors influencing the break-even price. Even under very optimistic assumptions, it was not possible to reduce the break-even price below that of conventional plant oils as competitive products. Therefore, economic feasibility of the process will probably only occur if on one hand considerable technical development and efficiency improvements of the production process are made while on the other hand plant and crude oil prices are continuously increasing.     

基于DEA—Malquist模型对煤炭企业全要素生产率的分析

通过2005--2007年数据,选取27家煤炭企业作为研究对象,对其进行效率评价。首先运用DEA方法分析了27家煤炭企业的总体效率状态,结论是效率不理想。分析找出煤炭企业效率低的原因,主要包括煤炭企业人员冗余严重、科研投入不足、煤炭企业自主创新能力低和体制改革不够彻底,最后分析了煤炭企业进行技术效率创新动力不足的原因。     

Using native epiphytic ferns to estimate the atmospheric mercury levels in a small-scale gold mining area of West Java, Indonesia

Mercury pollution is caused by artisanal and small-scale gold mining (ASGM) operations along the Cikaniki River (West Java, Indonesia). The atmosphere is one of the primary media through which mercury can disperse. In this study, atmospheric mercury levels are estimated using the native epiphytic fern Asplenium nidus complex (A. nidus) as a biomonitor; these estimates shed light on the atmospheric dispersion of mercury released during mining.Samples were collected from 8 sites along the Cikaniki Basin during September-November, 2008 and September-November, 2009.The A. nidus fronds that were attached to tree trunks 1-3 m above the ground were collected and measured for total mercury concentration using cold vapor atomic absorption spectrometry (CVAAS) after acid-digestion. The atmospheric mercury was collected using porous gold collectors, and the concentrations were determined using double-amalgam CVAAS.The highest atmospheric mercury concentration, 1.8 × 10³ ± 1.6 × 10³ ng m⁻³, was observed at the mining hot spot, and the lowest concentration of mercury, 5.6 ± 2.0 ng m⁻³, was observed at the remote site from the Cikaniki River in 2009. The mercury concentrations in A. nidus were higher at the mining village (5.4 × 10³ ± 1.6 × 10³ ng g⁻¹) than at the remote site (70 ± 30 ng g⁻¹). The distribution of mercury in A. nidus was similar to that in the atmosphere; a significant correlation was observed between the mercury concentrations in the air and in A. nidus (r = 0.895, P < 0.001, n = 14). The mercury levels in the atmosphere can be estimated from the mercury concentration in A. nidus using a regression equation: log (Hg_A.nidu/ng g⁻¹) = 0.740 log (Hg_Air/ng m⁻³) − 1.324.     

东北地区开发规模扩张的资源环境响应演变及影响因素

提出"区域开发规模扩张的资源环境响应"的概念,并构建了区域开发规模扩张的资源环境响应指数、响应度模型及评价指标体系,通过定量分析1995-2008年东北地区开发规模扩张的资源环境响应变化及影响因素,得出以下结论:1995年以来东北地区开发规模不断扩大,而资源环境水平总体呈现出"先升后降"的波动变化态势。资源环境对东北地区开发规模扩张具有由"正响应"向"负响应"转变的特征,与此相对应,区域开发规模扩张对资源环境的影响程度也呈现出由"弱促进"向"强胁迫"变化的态势,这说明近年来在东北地区开发规模加速扩展的同时,其对区域资源环境造成的压力也日益增大。1995-2008年由经济快速增长导致的资源环境压力增长是引致东北地区开发规模扩张对资源环境影响由"正向促进"向"负向胁迫"转化的重要内部因素,而区域投资的不断增长以及工业的快速发展是东北地区开发规模扩张对资源环境影响由"弱促进"向"强胁迫"变化的主要因素。     

电磁阻垢技术在火电厂大型循环水系统中的适用性研究

通过电磁阻垢技术在火电厂大型循环水系统中的应用情况进行研究分析,发现火电厂大型循环冷却水系统单独采用电磁阻垢处理方式和传统化学加药处理方式相比尚有欠缺,电厂在选择电磁阻垢处理方式进行循环水系统处理时应持谨慎态度,应用前应进行考证和试验。对于已采用电磁阻垢处理方式的电厂应加强循环水水质监督和机组热力参数监督,一旦发生异常情况,应立即恢复化学加药处理或进行两种方式的联合处理。     

The significance of heterogeneity on mass flux from DNAPL source zones: an experimental investigation

Understanding the process of mass transfer from source zones of aquifers contaminated with organic chemicals in the form of dense non-aqueous phase liquids (DNAPL) is of importance in site management and remediation. A series of intermediate-scale tank experiments was conducted to examine the influence of aquifer heterogeneity on DNAPL mass transfer contributing to dissolved mass emission from source zone into groundwater under natural flow before and after remediation. A Tetrachloroethylene (PCE) spill was performed into six source zone models of increasing heterogeneity, and both the spatial distribution of the dissolution behavior and the net effluent mass flux were examined. Experimentally created initial PCE entrapment architecture resulting from the PCE migration was largely influenced by the coarser sand lenses and the PCE occupied between 30 and 60% of the model aquifer depth. The presence of DNAPL had no apparent effect on the bulk hydraulic conductivity of the porous media. Up to 71% of PCE mass in each of the tested source zone was removed during a series of surfactant flushes, with associated induced PCE mobilization responsible for increasing vertical DNAPL distributions. Effluent mass flux due to water dissolution was also found to increase progressively due to the increase in NAPL-water contact area even though the PCE mass was reduced. Doubling of local groundwater flow velocities showed negligible rate-limited effects at the scale of these experiments. Thus, mass transfer behavior was directly controlled by the morphology of DNAPL within each source zone. Effluent mass flux values were normalized by the up-gradient DNAPL distributions. For the suite of aquifer heterogeneities and all remedial stages, normalized flux values fell within a narrow band with mean of 0.39 and showed insensitivity to average source zone saturations.     

Can Basin Land Use Effects on Physical Characteristics of Streams Be Determined at Broad Geographic Scales?

The environmental setting (e.g., climate, topography, geology) and land use affect stream physical characteristics singly and cumulatively. At broad geographic scales, we determined the importance of environmental setting and land use in explaining variation in stream physical characteristics. We hypothesized that as the spatial scale decreased from national to regional, land use would explain more of the variation in stream physical characteristics because environmental settings become more homogeneous. At a national scale, stepwise linear regression indicated that environmental setting was more important in explaining variability in stream physical characteristics. Although statistically discernible, the amount of variation explained by land use was not remarkable due to low partial correlations. At level II ecoregion spatial scales (southeastern USA plains, central USA plains, and a combination of the western Cordillera and the western interior basins and ranges), environmental setting variables were again more important predictors of stream physical characteristics, however, as the spatial scale decreased from national to regional, the portion of variability in stream physical characteristics explained by basin land use increased. Development of stream habitat indicators of land use will depend upon an understanding of relations between stream physical characteristics and environmental factors at multiple spatial scales. Smaller spatial scales will be necessary to reduce the confounding effects of variable environmental settings before the effects of land use can be reliably assessed.