环境污染与城乡收入差距:作用机制与基于中国经济事实的检验

环境污染是与居民健康水平紧密相关的,并且会导致处于不同收入阶层的居民的健康人力资本投资决策呈现出异质性特征,从而影响居民收入差距。本文通过构建跨期经济模型研究环境污染对城乡收入差距的影响,研究发现:环境污染导致城镇居民和农村居民出现相同比例的健康损害,这种损害会拉大城乡居民绝对收入差距;处于低收入阶层的农村居民应对环境污染带来的健康损害会进行相对较少的健康人力资本投资,因而城乡居民的健康水平差异会逐渐拉大,所以城乡收入的相对差距也会随着环境污染的加剧而扩大。基于理论研究结果,运用中国2002—2013年的省级面板数据进行实证研究发现:(1)环境污染对中国城乡收入差距的影响显著为正,并且基于人均二氧化硫排放量和人均废水化学需氧量排放量的计量检验结果是一致的,这表明研究结论是稳健的;(2)运用门槛面板模型的计量结果表明当滞后一期的城乡收入差距增加到临界点之后,环境污染对城乡收入差距的正效应会明显增强,表明环境污染对处于不同收入阶层的城镇居民和农村居民的健康人力资本投资决策有显著的影响,环境污染进一步拉大城乡居民的相对收入差距;(3)本文的研究结果证明了在教育、政府行为、城镇化等影响城乡收入差距的核心因素之外,环境污染也是影响中国城乡居民收入差距的显著性因素,并且其影响会随着环境污染的加剧和期初收入差距的拉大而变得更加严重,因此在治理中国城乡收入差距的过程中,相关政策应该平衡环境污染成本在城镇居民和农村居民之间的分配。     

Heterogeneity of farmers' preferences towards agri-environmental schemes across different agricultural subsystems

Specialised literature on the uptake of agri-environmental schemes (AES) has paid little attention to how this can be influenced by the different types of agricultural systems. This paper analyses the heterogeneity of farmers' preferences towards these schemes, distinguishing between different subsystems within the same agricultural system. We use the choice experiment method to analyse the case study of three olive grove subsystems in southern Spain, with the subsystems ranging from extensive to intensive. The results reveal inter- and intra-subsystem heterogeneity of farmers' preferences towards AES, both in general and specifically related to scheme attributes. A variety of factors appear to lie behind inter-subsystem heterogeneity, especially those associated with subsystem specificities (principally, the type of joint production). Likewise, numerous factors play a role in intra-subsystem heterogeneity, most of them related to farm/farmer socio-economic and physical characteristics. These findings will help in the design of more efficient AES.     

Does the presence of wind turbines have negative externalities for people in their surroundings? Evidence from well-being data

Throughout the world, governments foster the deployment of wind power to mitigate negative externalities of conventional electricity generation, notably CO₂ emissions. Wind turbines, however, are not free of externalities themselves, particularly interference with landscape aesthetics. We quantify these negative externalities using the life satisfaction approach. To this end, we combine household data from the German Socio-Economic Panel Study (SOEP) with a novel panel dataset on over 20,000 installations. Based on geographical coordinates and construction dates, we establish causality in a difference-in-differences design. Matching techniques drawing on exogenous weather data and geographical locations of residence ensure common trend behaviour. We show that the construction of wind turbines close to households exerts significant negative external effects on residential well-being, although they seem both spatially and temporally limited, being restricted to about 4000 m around households and decaying after five years at the latest. Robustness checks, including view shed analyses based on digital terrain models and placebo regressions, confirm our results.     

基于MODIS的华东地区气溶胶光学厚度时空变化特征分析

选用2001年1月-2015年12月MODIS数据,运用线性趋势等方法研究华东地区气溶胶光学厚度(AOD)的变化特征及影响因素。结果表明,2001-2015年华东地区AOD平均值变化范围在0.4~0.7之间,且呈现递减趋势。山东省西部、安徽省北部及江苏省AOD相对较高;福建省、浙江省南部及江西省南部地区AOD较低。华东地区气溶胶最低值出现在12月,最高值出现在6月;虽然冬季AOD变化趋势增长较高,但最高值仍出现在夏季。AOD主要受地形、NDVI、风速及人类活动等因素的影响,地形、NDVI、风速均与AOD呈负相关。     

Gender differences in wayfinding in virtual environments with global or local landmarks

This study assesses gender differences in wayfinding in environments with global or local landmarks by analyzing both overall and fine-grained measures of performance. Both female and male participants were required to locate targets in grid-like virtual environments with local or global landmarks. Interestingly, the results of the two overall measures did not converge: although females spent more time than males in locating targets, both genders were generally equivalent in terms of corrected travel path. Fine-grained measures account for different aspects of wayfinding behavior and provide additional information that explains the divergence in overall measures; females spent less time traveling away from the target location, a higher proportion of time not traversing, and made more rotations when stopping than males did. Rather than unequivocally supporting male superiority in wayfinding tasks, both the overall and fine-grained measures partially indicate that males and females are differentially superior when using global and local landmark information, respectively. To summarize, males moved faster than females but did not necessarily navigate the spatial surroundings more efficiently. Each gender showed different strengths related to wayfinding; these differences require the application of both overall and fine-grained measures for accurate assessment.     

Toward a Sustainable Utilization of Land Resources in China: Problems,Policies, and Practices

China’s economy is growing explosively with double-digit rates of growth. However, behind the scenes of this economic miracle, a dark underbelly exists. The potential impact of the unsustainable use of land resources is increasing. Each parcel of land has a stationary geographic location, while its utilization is optional. The re-adjustment and optimization of land use patterns ought to be encouraged. Spatial reconstruction refers to the combination of various land elements, which can promote the rational and efficient allocation of land resources through a four-layer action framework: the development of unused land, urban renewal, ecological reconstruction, and spatial displacement. The feasibility and validity of these methods are illustrated by practical cases in different provinces in China. We thus propose that pursuing sustainable development and building an ecological civilization will be necessary for China in future decades.     

Integration of Land-Sharing and Land-Sparing Conservation Strategies Through Regional Networking: The Mesoamerican Biological Corridor as a Lifeline for Carnivores in El Salvador

Nations with little remaining natural habitat and small extent are challenged when trying to achieve biodiversity targets. We show that the Central American nation of El Salvador cannot viably sustain populations of 87 % of its extant carnivores, especially in the case of large-bodied species with low population densities. Current land-sparing strategies will not suffice; therefore we propose that land-sharing strategies be implemented in tandem with protected areas to expand current conservation efforts via new regional networks. In Central America such a network can be established by linking international protected area systems in a way that implements the existing vision for the Mesoamerican Biological Corridor. Specifically, we propose a re-envisioning of the Mesoamerican Biological Corridor in which land-sharing practices are adopted throughout the agricultural matrix while ensuring formal protection of the remaining natural habitat. Such an integration of land-sparing and land-sharing could result in the creation of an effective network of protected areas, thereby increasing the probability of safeguarding species with populations that overlap national borders.     

Distribution of perfluorinated compounds in surface water from Hanjiang River in Wuhan,China

This study provided the first spatial distribution of perfluorinated compounds (PFCs) in Hanjiang River in Wuhan, China (HR). Surface water samples, collected from 23 sites in HR were analyzed for eight PFCs. The total concentrations of PFCs ranged from 8.90 to 568 ng L⁻¹, while perfluoropentanoic acid (PFOA, <LOQ − 256 ng L⁻¹) and perfluorooctane sulfonate (PFOS, <LOQ − 88.9 ng L⁻¹) dominated. All data were found to be normally distributed in the river. Similar spatial distribution tendencies were found among perfluorocarboxylates (PFCAs) and significant correlations were observed among PFCAs, while no significant correlations were found between PFOS and PFCAs. The distributions of PFCs were highly influenced by the industrial discharge and urban activities. The flux of PFCs from HR to the Yangtze River was estimated in the range of 16.9–127 kg yr⁻¹. More than a half of the samples studied could not meet the drinking water standards and avian wildlife values, suggesting further studies of characterizing PFCs and their potential risk to human were needed.     

武汉市耕地景观游憩功能与可达性的空间匹配格局

揭示耕地景观游憩功能的供给能力与其可达性的空间匹配格局,可以为耕地景观游憩功能的合理布局、开发与利用提供依据。以武汉市为例,采用指标评价法和专家打分法,结合GIS空间分析,建立了耕地景观游憩功能的空间格局研究框架,对耕地景观游憩功能的供应潜力、可达性、及两者空间匹配等方面开展了研究。结果表明:(1)武汉市耕地景观游憩功能供应潜力的空间分布呈现从中心城区边缘向外逐渐降低的格局;(2)武汉市耕地景观游憩功能可达性呈现"中西部高,边缘低"的分布格局;(3)根据耕地景观游憩功能的供应潜力与可达性的空间匹配关系,将武汉市耕地景观游憩服务分为四类:高供应-高可达,高供应-低可达,低供应-高可达,低供应-低可达;这四类面积分别占研究区域的26.17%、25.24%、17.33%、31.26%。对耕地景观游憩功能的合理开发与利用、促进耕地利用的多功能化具有重要的现实意义。