重庆直辖以来乡村人居环境可持续发展力及其时空分异研究

乡村人居环境是一复杂巨系统,其可持续发展力是各子系统间物质、信息与能量相互流通与交换的结果,本文从经济发展、生产生活、生态环境3个子系统入手构建乡村人居环境可持续发展力的评价指标体系,以1997—2015年重庆市37个区县的面板数据为数据源,运用发展水平(衡量乡村人居环境可持续发展态势)、发展效率(反映乡村人居环境发展趋向可持续的快慢程度)和协调指数(反映各子系统发展水平均衡程度)构建乡村人居环境可持续发展力测度模型,分析了乡村人居环境可持续力并探究其时空分异特征,为因地制宜践行《农村人居环境整治三年行动方案》提供策略支持。结果表明：1997—2015年,乡村人居环境可持续发展力时序上总体态势向好,其中发展水平逐步上升,发展效率波动剧烈,协调性稳步提高,各子系统间可持续发展力差异性较大;乡村人居环境可持续发展力在空间上总体呈现西高东低、“中心-边缘”的分异格局,区县间差异性明显,其中经济发展子系统呈“多级核心-外围”辐射圈层式差异化增长格局、生产生活子系统呈自西向东扩散式增长格局,生态环境子系统总体上先降后升,呈波浪式不均衡增长格局;从政府“制导引导”、城乡“双轮”联动、“点-极-核”整治模式等方面提出了相关整治策略。     

区域一体化与制度距离作用下的中国企业跨境并购

在区域一体化蓬勃发展的背景下,研究企业跨境并购有助于更好地理解资本在区域间的流动。论文基于BVD-Zephyr数据库统计的2003—2017年中国企业跨境并购数据,分析了交易双方是否签订区域一体化协定和彼此间的制度距离对跨境并购成功率和交易金额的影响。通过Heckman两阶段回归,研究发现：① 区域一体化能够促进中国企业达成跨境并购交易,但不能提升交易金额;② 中国企业与正式制度距离远,即法律、规制层面差异大的国家内企业完成跨境并购的可能性更高,但正式制度距离的存在不利于交易规模扩大;③ 非正式制度距离与交易完成呈负相关关系,即文化层面上的差异过大不利于中国企业完成跨境并购。然而交易一旦完成,非正式制度距离大的贸易双方交易金额更高。此外,论文还认为,随着区域一体化进程的深化,内部成员国之间正式制度距离会衰减,其对交易规模的阻碍作用也会被削弱。     

大气污染物排放量与颗粒物环境空气质量的空间非协同耦合研究——以武汉市为例

针对区域大气污染物排放量与空气质量在时空分布上存在不完全协同、匹配的现象,论文选择SO₂、NO_X、PM_2.5、CO和VOCs作为大气污染物指标,选择气溶胶光学厚度(Aerosol Optical Depth, AOD)表征颗粒物环境空气质量,以武汉市为例,综合应用耦合模型和空间错位指数模型研究2类指标之间的空间非协同耦合规律。主要结论如下：① 武汉市大气污染物排放量与颗粒物空气质量具有不同空间分布特征,大气污染物排放量呈现由城市中心城区向远城区递减的趋势,其中SO₂、PM_2.5和VOCs的排放具有明显的中心聚集现象,而NO_X和CO聚集现象不显著,且与道路分布明显相关;AOD分布具有明显的空间差异性,总体上呈由西北向东南依次递减的趋势。② 武汉市大气污染物排放与颗粒物空气质量的空间非协同耦合规律：越靠近城市中心城区,空间协同耦合现象越显著,空间错位现象越弱;越远离主城区,空间非协同耦合现象越显著,空间错位现象越显著;SO₂排放量与AOD在武汉市远城区的空间错位指数均大于0.7,且耦合度指数小于0.3,呈现较强的非协同耦合特征,NO_X、VOCs、PM_2.5的排放量与AOD在武汉中心城区的空间错位指数均小于0.5,且耦合度指数大于0.5,协同耦合现象较为显著。③ 基于时空非协同耦合分析城市大气环境污染治理建议：针对污染物与AOD空间错位不显著的城市中心城区,以本地减排治理为主;针对污染物与AOD空间错位显著的远城区,应在污染溯源分析的基础上进行区域协调综合治理。     

西部欠发达城市人口空间分布与演变

探索西部欠发达城市人口空间格局及其演变特征,与东部发达城市人口分布形成对照,有利于认识城市人口分布规律,引导城市人口有序疏解。以西部欠发达城市兰州为例,对其乡镇街道尺度的常住人口数据进行空间化处理,在此基础上借鉴标准差椭圆分析思路,提出变形椭圆圈层法,并结合GIS空间分析和人口密度模型拟合等方法,多角度揭示2000-2010年兰州市人口空间分布格局及其演变特征。研究发现：兰州市人口分布呈现“带状集聚”特征和“圈层-分异”结构,形成“中心区和近郊区人口缓慢增长,外围区人口快速增长,远郊区人口明显减少”的格局;兰州市人口重心在10年间向东偏北方向移动,人口空间呈“西北-东南”分布格局,总体上表现出集聚态势,且10年间集聚态势有所强化;Smeed模型是刻画兰州市人口分布的最佳单中心模型,10年间人口分布的单中心趋势增强,人口多中心结构尚不成熟。     

Extraction of Lithium from Salt Lake Brine using N523-TBP Mixture System

In this work,problems encountered by tri-butyl phosphate( TBP) in the industrialization of lithium extraction from salt lake brine were discussed in detail. The behavior of N,N-bi-( 2-ethylhexyl) acetamide( N523) during lithium extraction was investigated,and its disadvantages were analyzed in the view of practical application. An N523-TBP mixture extraction system was proposed to alleviate or avoid the defects that N523 and TBP met when they were used separately. The optimal composition of this mixture extraction system was determined to be 20% N523-30% TBP-50% kerosene.The effects of brine acidity,Fe/Li molarity ratio,phase ratio and chloride ion concentration on lithium extraction efficiency were discussed. The operation conditions in single-stage extraction were optimized as brine acidity = 0. 05 mol/L,Fe/Li molarity ratio = 1. 3,and phase ratio = 2. The high concentration of chloride ions in brine was beneficial for the extraction of lithium. The structure of the extracted complex was proposed as( LiFeCl_4·n N523·m TBP)·( 2-n) N523·( 2-m) TBP( m + n = 2) by chemical analysis and slope-fitting methods. The extraction thermodynamic functions were calculated preliminarily,and the results suggested that the extraction process was an exothermic( ΔH 0) and spontaneous( ΔG 0) reaction,and the degree of disorder increased( ΔS 0) during the extraction process. This work will give some guidance to the lithium industry of Qinghai in both the fundamental theory and practical application.     

The Belt and Road: Geographical pattern and regional risks

Journal of Geographical Sciences - Building the Belt and Road is initiatives of China to promote win-win international cooperation in the new era, aiming at green, health, intellect and peace and...     

How changes of groundwater level affect the desert riparian forest ecosystem in the Ejina Oasis,Northwest China

Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins. This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling(WAVES) model to simulate the Ejina Desert riparian forest ecosystem changes,China, to assess effects of groundwater-depth change on the canopy leaf area index(LAI) and water budgets, and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest. Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes. The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest, and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases. Groundwater changes could significantly influence water budgets for T. chinensis and P. euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests. Maintaining the annual mean groundwater depth at around 1.7-2.7 m is critical for healthy riparian forest growth. This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin.     

Species Abundance Distribution Patterns of a Toona ciliata Community in Xingdoushan Nature Reserve

With the goal of model fitting species abundance distribution patterns of the tree, shrub and herb layers of the natural Toona ciliata community in Xingdoushan Nature Reserve, Enshi Autonomous Prefecture, Hubei Province, we used the data collected from the field survey and employed different ecological niche models. The models tested were the broken stick model (BSM), the overlapping niche model (ONM) and the niche preemption model (NPM), as well as three statistic models, the log-series distribution model (LSD), the log-normal distribution model (LND) and the Weibull distribution model (WDM). To determine the fitted model most suitable to each layer, the fitting effects were judged by criteria of the lowest value of Akaike Information Criterion (AIC), Chi-square and the K-S values with no significant difference (P>0.05) between the theoretical predictions and observed species abundance distribution values. The result showed: (1) The fitting suitability and goodness of fit of the tree, shrub and herb layers by using the three ecological niche models were ranked as: NPM>BSM>ONM. Of the three statistical models, by accepting the fitting results of the three layers, WDM was the best fitting model, followed by LND. By rejecting the fitting tests of the herb layer, LSD had the worst fitting effect. The goodness of the statistical models was ranked as: WDM>LND>LSD. In general, the statistical models had better fitting results than the ecological models. (2) T. ciliata was the dominant species of the tree layer. The species richness and diversity of the herb layer were much higher than those of either the tree layer or the shrub layer. The species richness and diversity of the shrub layer were slightly higher than those of the tree layer. The community evenness accorded to the following order: herb>shrub>tree. Considering the fitting results of the different layers, different ecological niche models or statistical models with optimal goodness of fit and ecological significance can be given priority to in studying the species abundance distribution patterns of T. ciliata communities.     

荒漠生态质量科学框架:概念、指标、监测及评估（英文）

荒漠生态系统是地球上最大的陆地生态系统,全球四分之一的人口生活在这一区域。清晰地定义荒漠生态系统生态质量,制定反映生态质量优劣的关键监测指标,集成"星–空–地"一体化监测技术、构建综合评价模型可为干旱区生态质量监测、促进区域可持续发展提供技术支撑。荒漠生态质量是指一定时空范围内荒漠生态系统要素、结构和功能的综合特征。该研究通过集成卫星、无人机和地面传感器网络的"星–空–地"一体化监测技术,在区域和站点两个尺度上对荒漠生态系统的生态要素、生物多样性和生态功能进行连续监测,通过标准化生态质量指标数值、厘定其阈值范围,构造判断矩阵建立生态质量综合评价模型,评价荒漠生态系统质量状况。本论文阐明了构建荒漠生态质量动态综合监测技术规范与评价方法的概念框架,为实现我国荒漠生态系统生态质量综合监测、科学诊断和定量评估提供理论基础。     

国家重点研发项目:中国陆地生态系统生态质量综合监测技术与规范研究（英文）

生态质量是指一定时空范围内生态系统要素、结构和功能的综合特征,具体表现为生态系统的状况、生产能力、结构和功能的稳定性、抗干扰和恢复能力。生态系统的质量是我国生态文明建设和生态环境监测的重要内容,多时空尺度观测技术的发展为生态系统质量监测与评价提供了新机遇,但同时也对国家尺度生态要素、生物多样性和生态功能的观测标准与技术规范提出了新的要求。本国家重点研发项目自2017年7月立项以来,围绕国家尺度生态质量监测技术与规范,开展了生态系统网络观测技术规范、台站生态要素监测、区域生物多样性和区域生态功能监测技术与规范的研究,在典型农林草湿地生态系统开展应用示范。项目在生态质量综合监测指标体系构建、生态系统研究网络观测技术、区域生物多样性和区域生态功能监测、基于无人机和机器学习的荒漠植被监测等方面取得了重要进展,促进了生态质量监测技术的发展。我们组织本专辑从不同视野集中系统介绍本项目已取得的生态质量监测技术和评价方法,以期促进生态学及其观测技术的发展。