中亚水热资源匹配特征及敏感性分析

从水热积指数出发,基于1931—2019年Climatic Research Unit（CRU）再分析资料,运用多时序分析方法,从多时间尺度分析中亚水热资源匹配空间特征和时序变化,并进行敏感归因探究。结果表明：（1）空间上中亚水热匹配条件存在相对优劣,优势区多分布于高纬及高山高原地带,水热资源匹配较差区域分布于南部沙漠。优势区多和同期降水高值区、潜在蒸散低值区和气温低值区重合,年际水热积指数变化不明显或呈弱下降趋势;较差区域多为同期潜在蒸散和气温高值区,降水低值区,水热积指数降低且年际变幅较大。（2）中亚水热资源匹配年内存在季节差异,春秋较好、冬季次之、夏季较差;在年际尺度上,1931—1974年,水热匹配条件呈现上升趋势;1974—2000年左右,水热匹配条件波动上升;2000—2019年,水热匹配条件下降,且在1971—1980年、1981—1990年、1990—2000年发生匹配条件突变。春夏秋季水热匹配变化趋势同年际趋势大致相同,冬季波动幅度较小。（3）在春、夏及年尺度上,主导敏感性因子为平均气温因子,在秋冬两季为降水因子;在高纬、高原高山区,水热积指数变化敏感性气候因子多为降水因子;中亚南部水热积指数变化对降水敏感性减弱,平均气温敏感性增加,且北部平均气温敏感性系数绝对值略低于南部;高山高原区域对极端温度变化较为敏感。     

Spatial distribution of organic geochemical record in the core sediments along the prominent zones of Central Kerala,India

The study investigated the origin, quality, composition, and trophic state of sedimentary organic matter (SOM) in core samples collected from three zones (Munambam, Vypin, Chettuva) of Central Kerala, India. The SOM exhibited enhanced levels for carbohydrate (CHO) followed by protein (PRT) and lipid (LPD); and phytopigment in the sediment followed the trend: Pheophytin (Pheo) > Carotenoid (carotend) > Chlorophyll-a (Chl-a) > Chlorophyll-b (Chl-b) > Chlorophyll-c (Chl-c). The low PRT: CHO ratio indicated a large amount of nonliving or aged organic matter in the sedimentary environment. Whereas the low Chl-a: Pheo ratio interprets the abundance of dead plant materials in the sediments. Correlation matrix showed strong association between organic matter and clay fraction of sediment. Furthermore, the strong interrelationships between biochemical components and chloropigments in all the zones suggested that SOM is strictly connected to phytodetritus deposition. Vypin zone near Vallarpadam Container Terminal revealed the presence of high biopolymeric carbon content. Besides, the PRT: CHO > 1 reflected the eutrophic condition at the same site but the low PRT: CHO ratio in the remaining stations displays the oligotrophic nature.     

滇中经济区生态环境现状及改善对策

以滇中经济区为研究对象,探讨和分析了滇中经济区目前的土地石漠化、水土流失、水资源短缺、水体污染、矿业污染以及重金属污染的生态环境现状,并从经济、社会以及生态环境协调发展的理念,从水土保持、石漠化的治理和开发、科技推广力度、生态环境建设的执法力度以及环保教育等方面提出了滇中经济区生态环境改善的对策。     

中部粮食主产区城镇化进程中农村土地变化的GIS分析和对策研究——以江西省为例

以中部地区的江西省为例,在分析其粮食产量变化轨迹基础上,选取1980、1995、2000年3个年份经过解译的LandsatTM遥感影像土地利用数据,应用GIS软件提取各年份土地利用类型及其面积数据,分析不同土地利用类型的变化轨迹,以及农业用地向城镇建设用地转变的面积及其分布。江西省的粮食总产量1978年开始不断提高,1985年后,年粮食总产量随年播种面积变化的趋势较明显,即播种面积高的年份,粮食的总产量也高。GIS分析结果显示,改革开放以来江西省绝大部分地区都出现了农业用地向城镇建设用地转变的现象,鄱阳湖平原地区成为农业用地向城镇建设用地转变的集中地区,农业用地向城镇建设用地转变较大的土地利用单元出现于京九铁路、浙赣铁路和湘赣铁路等交通沿线的大、中型城市周围。城镇化导致了耕地大面积减少,从而影响了粮食产量,协调对策主要有提高播种面积,引种优良作物品种,提高农民的种粮积极性等。     

区域分异视角下乡村企业入城意愿分析——基于浙、豫、川三省193家企业的实证研究

乡村企业入城是实现我国城镇化发展的基本路径。利用浙江、河南、四川三省193家乡村企业的实地调查数据,运用多元有序Logistic回归模型进行相关验证,实证分析我国东中西部三个省份的乡村企业入城意愿及其影响因素。通过对调研数据的描述统计发现:有58.55%的乡村企业主有入城意愿,仅有21.24%的乡村企业主不愿意或非常不愿意搬迁,集群环境、土地价格、运输成本等是企业愿意搬迁的主要原因,土地价格政策、当地经济发展水平、产品产销信息、集群环境是影响企业搬迁方向的重要因素,当地的土地、税收和融资等政府政策对于企业是否入城产生重要影响。通过多元有序Logistic回归模型估计结果表明:企业总资产、土地价格、运输成本、集群环境、与政府关系对入城意愿有显著负向影响,税收政策有显著正向影响,这些影响因素主要是通过影响企业的显性成本(土地价格、运输成本),以及企业的交易成本、寻租成本等隐性成本(集群环境、与政府关系和税收政策),进而影响企业的迁移意愿,且浙江、河南与四川三地计量结果差异显著。在上述研究的基础上,本文提出相应的政策建议。     

加强铁路集中空调通风系统管理的探讨

为避免集中空调通风系统传播、扩散空气传播性疾病的安全隐患,在概述集中空调通风系统在某铁路局集团公司客运站应用的基础上,从首选自然通风、确保供风安全、加强通风系统清洗消毒等方面说明加强铁路客运站通风系统管理的措施,提出明确责任分工、健全卫生管理制度、开展卫生学评价、做好监督检查和应急处理等保障措施,从而有效阻断传播途径,保障广大旅客和铁路工作人员身体健康。     

Impact of the 1998 Central American fires on PM2.5 mass and composition in the southeastern United States

The impact of the Central American fires on PM_2.5 mass concentration and composition in the Tennessee Valley region during portions of May, 1998, has been quantified. Elevated concentrations of smoke aerosol tracers—fine potassium, (and to a lesser extent, calcium and silicon) and, where available, organic and elemental carbon—were observed in the region during times in which satellite imagery (TOMS and GOES-8) showed regional transport of hazy, smoky airmasses from southern Mexico and adjacent areas of Central America. Back-trajectories from network sites in the Tennessee Valley network were consistent with this regional transport. The extent of transport of extra-regional fine particle mass during May, 1998, is discussed relative to the new US fine particle mass-based standards for fine particulate matter.     

Cattle Grazing Mediates Climate Change Impacts on Ephemeral Wetlands

Abstract:  Climate change impacts depend in large part on land-management decisions; interactions between global changes and local resource management, however, rarely have been quantified. We used a combination of experimental manipulations and simulation modeling to investigate the effects of interactions between cattle grazing and regional climate change on vernal pool communities. Data from a grazing exclosure study indicated that 3 years after the removal of grazing, ungrazed vernal pools dried an average of 50 days per year earlier than grazed control pools. Modeling showed that regional climate change could also alter vernal pool hydrology. Increased temperatures and winter precipitation were predicted to increase periods of inundation. We evaluated the ecological implications of interactions between grazing and climate change for branchiopods and the California tiger salamander (  Ambystoma californiense ) at four sites spanning a latitudinal climate gradient. Grazing played an important role in maintaining the suitability of vernal pool hydrological conditions for fairy shrimp and salamander reproduction. The ecological importance of the interaction varied nonlinearly across the region. Our results show that grazing can confound hydrologic changes driven by climate change and play a critical role in maintaining the hydrologic suitability of vernal pools for endangered aquatic invertebrates and amphibians. These observations suggest an important limitation of impact assessments of climate change based on experiments in unmanaged ecosystems. The biophysical impacts of land management may be critical for understanding the vulnerability of ecological systems to climate change.     

面向SDGs的城市扩张多情景模拟——以“一带一路”中亚区为例

在全球倡导可持续发展目标（SDGs）的背景下,城市作为人类活动的主要场所,既是SDGs的聚焦区域,更是世界各国落实SDGs的着力点。以“一带一路”沿线中亚五国首都城市区为例,面向SDGs设定发展情景和相应参数,采用Markov-FLUS模型模拟2030年自然发展、生态优先与经济优先情景下的城市发展格局,权衡SDGs与多情景城市格局演化规律,从空间视角协调城市的社会、生态与经济,提供城市发展的决策依据。结果表明：（1）2010—2015年来,研究区均出现建设用地总量增加、生态用地总量减少的现象。（2）未来情景模拟中均表现出由建设用地扩张引致的生态用地破碎化;生态优先情景有效抑制了建设用地扩张;经济优先情景下转化为裸地的土地有所减少,建设用地出现连片扩张。（3）未来城市发展应协调生态保护与经济发展,将生态保护理念融入城市建设,实现国家政策推动土地资源可持续利用,促进实现2030年全球可持续发展目标。     

The Effects of Long-Term Grazing Exclosures on Range Plants in the Central Anatolian Region of Turkey

Over the last fifty years, almost half of the steppe rangeland in the Central Anatolian Region of Turkey (CAR) has been converted to cropland without an equivalent reduction in grazing animals. This shift has led to heavy grazing pressure on rangeland vegetation. A study was initiated in June 2003 using 6 multiscale Modified-Whittaker plots to determine differences in plant composition between areas that have not been grazed in 27 years with neighboring grazed plant communities. A total of 113 plant species were identified in the study area with the ungrazed plots containing 32 plants more than the grazed plots. The major species were Astragalus acicularis, Bromus tomentellus, Festuca valesiaca, Genista albida, Globularia orientalis, Poa bulbosa, and Thymus spyleus ssp rosulans. Grazing impacts on forbs were more pronounced than for grasses and shrubs. Based on Jaccard’s index, there was only a 37% similarity of plant species between the two treatments. Our study led to four generalizations about the current grazing regime and long-term exclosures in the steppe rangeland around the study area: (1) exclosures will increase species richness, (2) heavy grazing may have removed some plant species, (3) complete protection from grazing for a prolonged period of time after a long history of grazing disturbance may not lead to an increase in desirable plant species with a concomitant improvement in range condition, and (4) research needs to be conducted to determine how these rangelands can be improved.