Determinants on Rural-Urban Labor Migration in China： Empirical Analysis on the Effect of Rural Cooperate Medical Insurance based on Cross-Sectional and Longitudinal Data

This paper studies factors influencing rural-urban labor migration in China,particularly the implementation of rural cooperative medical insurance(RCMI) in the year 2003.With the support of data analysis from the year 2000,2004 and 2006,clear linear correlations are found between gender,income,health condition and rural-urban labor flow,whereas the impact of education and employment status are more complicated.More importantly,results from regression show that the establishment of RCMI in countryside of China not only inhibits rural residents from seeking employment outside the village,but also pulls back rural people who have already worked in cities.When regional dimension is concerned,the pure composite effect of RCMI on rural labor flow is less significant in coastal areas with better economic performance and medical service.     

硬岩金属矿山开采活动与矿山地震活动的关系研究

以冬瓜山微震监测的数据为基础,结合开采、地质条件等因素,运用统计学和线形拟合方法,研究了开采活动与矿山地震活动的关系特征。其结果发现:累积矿震事件数与累积采掘体积、爆破药量存在着双对数线性的正比例关系;而累积矿震能量却与开采体积存在着斜率为负的双对数线性关系;较大矿震事件主要发生在开采爆破活动之后的时间内,震级大于0的矿震事件在时间上要超前爆破事件,矿震活动在开采活动之后呈现从强到弱再从弱到强的变化过程。该结果对硬岩金属矿山的矿震活动研究有一定的参考价值。     

Source Apportionment of Particulate Matter (PM10) and Indoor Dust in a University Building

A study on source apportionment of indoor dust and particulate matter (PM₁₀) composition was conducted in a university building by using chemometrics. The objective of this study was to investigate the potential sources of selected heavy metals and ionic species in PM₁₀ and indoor dust. PM₁₀ samples were collected using a low-volume sampler (LVS) and indoor dust was collected using a soft brush. Inductively coupled plasma spectrometry (ICP-MS) was used to determine the concentration of heavy metals, while the concentration of cations and anions was determined by atomic absorption spectrometer (AAS) and ion chromatography (IC), respectively. The concentration of PM₁₀ recorded in the building throughout the sampling period ranged from 20 ± 10 μgm^?3 to 80 ± 33 μgm^?3. The composition of heavy metals in PM₁₀ and indoor dust were dominated by zinc (Zn), followed by lead (Pb), copper (Cu), and cadmium (Cd). Principle component analysis (PCA) and multiple linear regression (MLR) showed that the main sources of pollutants in PM₁₀ came from indoor renovations (73.83%), vehicle emissions (16.38%), earth crust sources (9.68%), and other outdoor sources (0.11%). For indoor dust, the pollutant source was mainly earth crust. This study suggests that chemometrics can be used for forensic investigation to determine the possible sources of indoor contaminants within a public building.     

水环境质量评价的模糊识别方法

在水环境质量评价中,本文运用模糊识别方法,通过建立因子集、隶属度和权重集,实现了对水体的质量等级评判.并且对指标权重、评价结果的最大隶属度原则进行了改进.     

不确定性下区域规划环评方案优化方法框架研究

为了弥补以往规划环评方案中存在的两个缺陷,构建了不确定性条件下融合型和调整型区域规划环评方案优化方法框架,从而消除规划方案本身潜在的环境影响,且实现了规划方案和环境保护补救措施的系统优化及其不确定性风险决策.同时,从方法学上,基于强化区间优化模型建立了不确定性条件下规划方案和补救措施的双层优化方法.最后,针对郑州市土地利用总体规划(1997～2010年)的规划环评,以生态系统服务功能价值的最大化为目标,以郑州市土地资源、经济发展(GDP)和环境指标(土地承载COD排放总量)为约束条件,得到不同风险水平下土地利用规划优化方案.结果表明:①优化后的规划方案的生态系统服务功能价值高于原规划方案,约为原规划方案的1.45～1.52倍,且完全能满足郑州市2010年GDP目标;②有必要在未来融合型或调整型规划环评融入不确定性优化思想,且需要为决策者提供不同环境风险水平下的决策方案.     

Single and joint stress of acetochlor and Pb on three agricultural crops in northeast China

In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.     

应用线性自由能关系估算药用活性化合物的生物碳质-水吸附系数

线性自由能关系(LFER)可以用来预测生物碳质对水中药用活性化合物(Ph ACs)的吸附系数,并确定不同分子间作用力对生物碳质吸附性能的相对贡献.利用商业水稻秸秆生物碳质(碳化温度400~500℃,200目)与14种带有不同表面官能团的Ph ACs(羧酸类、羟基类、氮杂环类)进行了吸附等温实验.各物质的等温吸附实验数据均可用Freundlich方程进行很好地拟合.通过建立的LFER模型,可以预测吸附质任一化学饱和水平(CW/SW)下的lg Kd,activity.利用复相关系数(R2=0.93)、回归系数标准偏差(SE=0.23)、F统计量(268)、去一法交叉验证系数(Q2LOO=0.90)以及外部样本交叉验证相关系数(Q2EXT=0.92)等方法对该模型进行验证,结果表明,其显著性与稳健性较好,具有预测能力.模型结果表明在低浓度范围内,空穴作用(V)与氢键碱作用(B)在整个吸附过程中起到主导作用,其中空穴作用为正贡献,氢键碱作用为负贡献.     

1982—2021年黄河流域植被覆盖时空演变及影响因素研究

通过科学认识黄河植被覆盖的空间格局、时间规律,揭示气候变化与人类活动对植被覆盖率空间演化的影响与机理,对于提出科学的生态防护方法、进行生态安全评价,以及推进黄河战略有着重大的理论意义与应用意义。本文以1982—2015年GIMMS NDVI和2000—2021年MODIS NDVI为主要数据源,通过最大值合成法、平均值法、Theil-Sen Median和Mann-Kendall等方法分析了黄河流域1982—2021年植被覆盖空间格局、月际和年际变化规律。结合同时段的年平均气温和年降水量,采用二元线性回归分析和残差分析等方法,探讨了黄河流域植被覆盖的主要影响因素。根据时空变化分析,1982—2021年黄河流域多年NDVI均值变化趋势由西北向东南依次增加,年际变化呈现波动增长趋势,增长速率为0.019 ? (10a)^?1,月际变化呈现先增后减的单峰曲线状分布,8月(0.50)为峰值。根据变化趋势分析,1982—2021年黄河流域77.35%的区域植被覆盖呈增加趋势。根据影响因素分析,黄河流域植被覆盖以气候变化和人类活动共同作用为主要影响因素,其中受人类活动促进作用较...     

空气污染健康损失中统计生命价值评估研究

采用权变评价法(CVM)评估了我国空气污染健康损失中的统计生命价值,并分析了其影响因素.结果表明,我国空气污染健康损失中的统计生命价值约为100万元/a.区间值线性回归模型分析显示,年龄、受教育程度、人均年收入、健康和家庭规模等因素对统计生命价值均有显著影响,但是城市的不同对统计生命价值并没有显著影响.     

Spatial pattern of impervious surfaces and their impacts on land surface temperature in Beijing, China

Land surface temperature （LST）, which is heavily influenced by urban surface structures, is a significant parameter in urban environmental analysis. This study examined the effect impervious surfaces （IS） spatial patterns have on LST in Beijing, China. A classification and regression tree model （CART） was adopted to estimate IS as a continuous variable using Landsat images from two seasons combined with QuickBird. LST was retrieved from the Landsat Thematic Mapper （TM） image to examine the relationships between IS and LST. The results revealed that CART was capable of consistently predicting LST with acceptable accuracy （correlation coefficient of 0.94 and the average error of 8.59%）. Spatial patterns of IS exhibited changing gradients across the various urban-rural transects, with LST values showing a concentric shape that increased as you moved from the outskirts towards the downtown areas. Transect analysis also indicated that the changes in both IS and LST patterns were similar at various resolution levels, which suggests a distinct linear relationship between them. Results of correlation analysis further showed that IS tended to be positively correlated with LST, and that the correlation coefficients increased from 0.807 to 0.925 with increases in IS pixel size. The findings identified in this study provide a theoretical basis for improving urban planning efforts to lessen urban temperatures and thus dampen urban heat island effects.