Origin and depositional environments of source rocks and crude oils from Niger Delta Basin: Carbon isotopic evidence     

《China Geology》2020,3(4):602-610

Thirty-nine crude oils and twenty-one rock samples from Niger Delta Basin, Nigeria have been characterized based on their isotope compositions by elemental analysis-isotope ratio mass spectrometry and gas chromatography-isotope ratio mass spectrometry. The bulk carbon isotopic values of the whole rock extracts, saturate and aromatic fractions range from –28.7‰ to –26.8‰, –29.2‰ to –27.2 ‰ and –28.5 ‰ to –26.7 ‰, respectively while the bulk carbon isotopic values of the whole oils, saturate and aromatic fractions range from –25.4 ‰ to –27.8 ‰, –25.9 ‰ to –28.4 ‰ and –23.5 ‰ to –26.9 ‰, respectively. The average carbon isotopic compositions of individual alkanes (nC₁₂-nC₃₃) in the rock samples range from –34.9‰ to –28.2‰ whereas the average isotopic values of individual n-alkanes in the oils range from –31.1‰ to –23.8‰. The δ¹³C isotope ratios of pristane and phytane in the rock samples range from –29.2 ‰ to –28.2 ‰ and –30.2 ‰ to –27.4 ‰ respectively while the pristane and phytane isotopic values range from –32.1‰ to –21.9‰ and –30.5‰ to –26.9‰, respectively. The isotopic values recorded for the samples indicated that the crude oils were formed from the mixed input of terrigenous and marine organic matter and deposited under oxic to sub-oxic condition in lacustrine-fluvial/deltaic environments. The stable carbon isotopic compositions were found to be effective in assessing the origin and depositional environments of crude oils in the Niger Delta Basin.  相似文献   

新时代的国土空间规划体系重建与制度环境改革     

王开泳  陈田 《地理研究》2019,38(10):2541-2551

在全面推进生态文明建设背景下,急需建立适合中国国情的国土空间开发保护制度和国土空间规划体系,这是新时期建立空间治理体系的重要任务。在国务院新一轮的机构改革背景下,空间类规划的编制职能向自然资源部集中,急需探索和建立全国国土空间规划体系的总体框架和制度环境改革的推进路径。研究表明：国家国土空间规划体系的重建取决于三个方面,一是依赖于部门的职能整合,二是国土空间规划体系的整合与重构,三是依赖于制度环境改革。因此,在机构改革逐步完成的形势下,需要从国土空间规划体系重建与制度环境改革两个路径着手,从国家、省域、市县等层面阐述了中国国土空间规划体系的重建思路,构建五级四类、上下衔接、分级管理的国土空间规划体系。从确定国土空间开发保护制度、专业人才培养、规划资质管理、推进立法等几个方面推进制度环境改革。最后从推进国土空间规划立法、审批程序前置和推进相关法律法规修改完善等方面提出具体举措,以确立国土空间规划的法定地位与统领作用。结合新时期国土空间规划编制,提出了尽快出台国土空间规划编制办法和技术规程、重新调整中国国土空间规划编制的时序安排、加强技术队伍建设等若干建议。  相似文献   

Land Resource Carrying Capacity in Xilin Gol Grassland Transects: A Perspective on Food Nutritional Demand     

YANG Wanni  ZHEN Lin  LUO Qi 《资源与生态学报(英文版)》2019,10(6):614-620

Food safety is an important issue for the development of the national economy and society. Studying regional food supply and demand from the perspective of land resource carrying capacity can provide new references for regional resource sustainability. This study uses the data from farmer and herdsmen household questionnaires, statistical data, land use data, and other sources to construct a land resource carrying capacity (LCC) assessment framework, targeting the food supply and demand of residents in representative areas, specifically the typical grassland pastoral areas, sandy pastoral areas and agro-pastoral areas on the Xilin Gol grassland transects. The three food nutritional indicators of calories, protein and fat were selected for analyzing the balance of land resource carrying capacity. We found that: 1) Along the Xilin Gol grassland, the main local food supply showed a shift from meat and milk to grains, vegetables and fruits. 2) From north to south along the grassland transects, the calorie intake increased gradually, while the intake of protein and fat was highest in pastoral areas and lowest in agricultural areas. 3) The overall land resource carrying capacity of the Xilin Gol grassland transects was in a surplus state, but the land carrying capacity of typical grassland pastoral area was higher than the two other types of areas. This study provides an empirical reference for the sustainable development of regional food nutrition.  相似文献   

中国市域居民住房支付能力时空演变及影响因素          下载免费PDF全文

康珈瑜  索志辉  梁留科  买哲  方明 《干旱区地理》2019,42(5):1153-1165

利用泰尔指数、σ系数、莫兰指数和空间回归模型等方法，对2012—2017年中国大陆346个市域单元收入房价比的时空演变规律进行分析，并探究其影响因素。结果表明：2012—2017年，中国市域单元收入房价比排名整体表现为东部>中部>东北>西部，其相对差异和绝对差异均随时间呈现增大趋势，居民住房支付能力稳步增强。2012—2017年，中国市域单元收入房价比的空间集聚性显著增强，空间分布不均衡性有逐渐增强的趋势。经济水平、城镇化水平、房地产投资水平、城市规模是影响中国市域住房支付能力的主要影响因素，其中，经济水平和城镇化水平对居民住房支付能力具有较大的正向影响，而房地产投资水平和城市规模为负向影响；2012—2017年我国东北和东中西部则不同程度上受不同影响因素的影响。  相似文献   

Analog simulation of urban construction land supply and demand in Chang-Zhu-Tan Urban Agglomeration based on land intensive use     

Xiong  Ying  Chen  Yun  Peng  Fen  Li  Jingzhi  Yan  Xiaojing 《地理学报(英文版)》2019,29(8):1346-1362

Journal of Geographical Sciences - Urban land intensive use is an important indicator in harmonizing the relationship between land supply and demand. The system dynamics (SD) can be used to...  相似文献   

新疆和田地区耕地面源污染生态风险评价          下载免费PDF全文

田丰收  刘新平  原伟鹏 《干旱区地理》2019,42(2):295-304

随着化肥、农膜等在农业生产中的过量投入，耕地面源污染的程度随之加重。文章选取塔里木河流域上游和田地区为研究区域，依据P-S-R框架理论，构建和田地区耕地面源污染生态风险评价指标体系，加入土壤理化数据，使用生态风险评价模型对和田地区1980 年及2016 年耕地面源污染状况进行生态风险评价，运用耕地生态风险模型、生态风险转移矩阵、Arcgis分析和田地区耕地面源污染时空分异状况。研究结论如下：和田地区1980 年耕地生态风险等级均为II级或III级，呈“中间高，两侧低”分布；2016 年耕地生态风险等级上升至IV级或V级，呈“倒W型”分布，各县耕地面源污染程度较1980 年均有较大幅度的上升，其中墨玉县和于田县在2016 年耕地生态风险等级达到最高的V级，而民丰县因自身生态环境的强脆弱性，同样需要提高关注。根据面源污染“从源头治理”的原则，应切实推进和田地区耕地生态环境保护与治理，提高政府重视程度，增强技术指导，开展试点工作，改善和田地区耕地面源污染现状。  相似文献   

Entrepreneurial causation and effectuation logics in a regional context: Assessing the importance of population density     

Jarle Aarstad  Stig-Erik Jakobsen 《Norsk geografisk tidsskrift. Norwegian journal of geography》2019,73(5):290-300

ABSTRACT

The purpose of the article is to assess whether an entrepreneurial causation or effectuation logic is a function of geographical location in densely populated economic regions versus sparsely populated economic regions. A causation logic implies that the entrepreneur primarily focuses on a predefined goal and further aims to identify the means to reach that goal. By contrast, an effectuation logic implies that the entrepreneur to a larger extent focuses on the means at hand, which she or he aims at materialising into one or more goals that are not necessarily predefined. The empirical data for the study are based on an investigation and evaluation of Norwegian entrepreneurs in business incubation that are located in many different economic regions of the country. Multilevel regression analyses showed that geographical location in sparsely populated economic regions is associated with a causation logic, whereas a location in densely populated economic regions is associated with an effectuation logic. An implication of the article is that entrepreneurial stakeholders, such as policymakers, incubator managers, public and private partners, and entrepreneurs themselves should be aware of differences in causation and effectuation logics between entrepreneurs located in densely versus sparsely populated economic regions.  相似文献   

13世纪以来中国海洋盐业动态演变及驱动因素     

鲍俊林  高抒 《地理科学》2019,39(4):596-605

海洋盐业是中国海洋经济的重要部分,也是沿海传统产业之一,13世纪以来不断发展演变。将沿海分为北、东、南3个地带,搜集整理与海盐经济相关的多种历史文献及方志资料,运用地理学方法分析评估了海洋盐业百年尺度的动态演化过程,并比较了资源环境与管理政策的驱动作用及其差异。研究表明：① 沿海盐业表现为传统煎法长期主导、逐步废煎改晒的过程,不同盐区的演化进程存在显著差异,北部盐区最快,东部次之,南部整体发展缓慢;② 海盐生产重心长期位于东部的两淮盐区,19世纪后期向北部盐区快速迁移;③ 资源环境与生态差异促进了各岸段海盐生产演化分异,垄断性管理政策迟滞了海洋盐业的空间集聚进程,未来沿海开发与海洋盐业的可持续发展将主要依靠基于资源生态约束的管理政策与技术。  相似文献   

Political ecology of tiger conservation in India: Adverse effects of banning customary practices in a protected area     

Nitin D. Rai  Tor A. Benjaminsen  Siddhartha Krishnan  C. Madegowda 《Singapore journal of tropical geography》2019,40(1):124-139

Protected areas have had significant impacts on local communities primarily through the physical removal of people. In some instances, people continue to live within protected areas due to the inability of the state to evict them. The restrictions on livelihoods placed on people living inside protected areas lead to in situ displacement. We show how conservation enclosures in the Biligiri Rangaswamy Temple Tiger Reserve have produced a class of people that the state ‘lets die’ by banning customary practices such as fire use, hunting and harvesting of forest produce. Using longitudinal ethnographic, socio‐economic and ecological data, we demonstrate that conservation policy has alienated indigenous forest dwellers from their agricultural and forest‐land. The outcomes of conservation policy include dispossession through increased crop losses, reduced income from agriculture and forest produce, as well as a forest that is dominated by weeds due to fire suppression. The ban on hunting in particular has increased wildlife densities, which has enabled the state to accumulate revenues through the establishment of wildlife tourism facilities. All in all, centralized protected area governance has changed the relationships among people, forest and the state in a way that has produced adverse effects for both livelihoods and the ecosystem.  相似文献   

内蒙古干湿环境演变与地区生态建设优势气候背景分析   总被引：1，自引：0，他引：1       下载免费PDF全文

代海燕  李丹  娜日苏  陈素华  都瓦拉 《干旱区地理》2019,42(4):745-752

通过内蒙古地区近46 a降水和潜在蒸散量以及湿润度在气温突变前后的倾向率和差值变化分析，得出该区域主要植被类型干湿环境演变的时空变化特征。研究结果表明：降水在气温突变前“东增西减”，突变后呈相反的变化趋势。46 a降水倾向率增加区域主要集中在呼伦贝尔市东部和乌兰察布市以西大部地区；潜在蒸散量在气温突变前呈减少趋势，突变后有增加趋势，突变后潜在蒸散量明显小于突变前。内蒙古46 a潜在蒸散量倾向率大部地区偏小，偏大区域仅存在于中东部偏北地区，气温突变后全区大部地区存在明显的“蒸发悖论”；大兴安岭西麓和乌兰察布市以西地区突变后湿润度增加明显，暖湿的气候环境有利于当地植被建设和生态恢复，内蒙古东南部、呼伦贝尔草原和锡林郭勒盟草原区有暖干化趋势，上述草原区存在潜在退化风险。  相似文献