海洋碳汇经济价值核算研究

海洋碳汇经济价值核算是推动海洋碳汇市场交易、促进海洋环境保护和生态修复的前提和基础。本文探讨了海洋碳汇及海洋碳汇价值内涵,提出海洋碳汇经济价值分狭义与广义两种,重点分析了广义海洋碳汇价值的特点和构成,运用“总经 济价值法”核算广义海洋碳汇价值,构建了分类价值指标体系和分类核算方法。最后从海洋碳汇资源调查监测方法学、评估与核算标准体系、海洋增汇项目开发、海洋碳汇政策保障等角度提出海洋碳汇发展的具体建议。     

China and the changing economic geography of coffee value chains

For the past three centuries, the economic geography of the global coffee sector has been characterized by the supply of beans from tropical countries for consumption in North America and Europe, with various modes of value chain coordination enacted by lead firms to ensure reliable and affordable supply. This pattern is now fundamentally changing, with growth in coffee consumption in emerging markets, including China, exceeding that in established markets. But China is not only a growing consumer market, it is less well known that rapidly increasing agricultural production in Yunnan province of southwest China has also inserted the country as an important source region for coffee, and this has been pivotal in facilitating the emergence of Chinese lead firms in the sector. This article presents the emergence of China, and Chinese firms, at a critical juncture for the structure and governance of the global value chain for coffee. The processes through which this is occurring are outlined, and the implications for regional development prospects across Southeast Asia are discussed. We argue that the changing economic geography of coffee value chains, and their increasing driven‐ness by Chinese actors, is starting to reshape the regional coffee industry in profoundly new ways.     

三大海洋经济区的海洋产业结构变动对海洋经济增长的贡献研究

20世纪90年代后期以来,我国海洋产业发展迅速,海洋产业结构变动巨大,各地区海洋经济差异显著。文章基于多部门经济模型,对1996—2015年我国三大海洋经济区的海洋产业结构变迁对海洋经济增长的贡献能力进行研究,运用回归分析对海洋三次产业结构变动的贡献度进行测算。结果表明:1996—2005年海洋产业结构变动剧烈,2006—2015年趋于平稳。三大海洋经济区中环渤海地区海洋产业结构总体变动较大,长三角次之,珠三角最小。海洋三次产业结构变动对海洋经济增长具有显著正向推动作用,1996—2005年海洋第一产业贡献能力明显,2006—2015年海洋第三产业贡献能力最大,第二产业次之。     

经济全球化、全球金融危机与中国——基于金融地理学的视角

2008—2009年的全球金融危机对西方发达国家尤其是英美经济体的影响是深远的,反映在经济、政治和社会的各个层面。相关学科的学者从不同的视角对金融危机的爆发作出了解释。论文尝试从金融地理学的角度分析经济全球化与全球金融危机之间的关系并探讨危机对中国的影响。首先,研究考察了经济全球化背景下新的国际劳动力分工的形成,指出了金融危机的传导机制,并描绘了金融危机对世界经济地理塑造的空间差异。对中国来说,全球金融危机是外部性的,西方发达国家的经济衰退和消费收缩直接影响了中国的出口,但危机并没有动摇中国的金融体系。其次,解释了为什么全球金融危机没有动摇中国的金融体系。制度的空间异质性、市场经济制度的多样性、政府积极的宏观调控和中国以银行主导的金融体系都是重要因素。第三,金融危机之后中西方金融地理学家对中国问题的兴趣逐渐增加,文章总结了最新的研究进展并指出其存在的不足之处。最后,在西方金融地理学最新研究进展的基础上,对中国金融地理学的学科构建提出了建议。     

Changes in air temperature over China in response to the recent global warming hiatus

The 1998-2012 global warming hiatus has aroused great public interest over the past several years. Based on the air temperature measurements from 622 meteorological stations in China, the temperature response to the global warming hiatus was analyzed at national and regional scales. We found that air temperature changed -0.221℃/10a during 1998-2012, which was lower than the long-term trend for 1960-1998 by 0.427℃/10a. Therefore, the warming hiatus in China was more pronounced than the global mean. Winter played a dominant role in the nationwide warming hiatus, contributing 74.13%, while summer contributed the least among the four seasons. Furthermore, the warming hiatus was spatial heterogeneous across different climate conditions in China. Comparing the three geographic zones, the monsoon region of eastern China, arid region of northwestern China, and high frigid region of the Tibetan Plateau, there was significant cooling in eastern and northwestern China. In eastern China, which contributed 53.79%, the trend magnitudes were 0.896℃/10a in winter and 0.134℃/10a in summer. In the Tibetan Plateau, air temperature increased by 0.204℃/10a, indicating a lack of a significant warming hiatus. More broadly, the warming hiatus in China may have been associated with the negative phase of PDO and reduction in sunspot numbers and total solar radiation. Finally, although a warming hiatus occurred in China from 1998 to 2012, air temperature rapidly increased after 2012 and will likely to continuously warm in the next few years.     

Exploring the uncertainty of activity zone detection using digital footprints with multi-scaled DBSCAN

ABSTRACT

The density-based spatial clustering of applications with noise (DBSCAN) method is often used to identify individual activity clusters (i.e., zones) using digital footprints captured from social networks. However, DBSCAN is sensitive to the two parameters, eps and minpts. This paper introduces an improved density-based clustering algorithm, Multi-Scaled DBSCAN (M-DBSCAN), to mitigate the detection uncertainty of clusters produced by DBSCAN at different scales of density and cluster size. M-DBSCAN iteratively calibrates suitable local eps and minpts values instead of using one global parameter setting as DBSCAN for detecting clusters of varying densities, and proves to be effective for detecting potential activity zones. Besides, M-DBSCAN can significantly reduce the noise ratio by identifying all points capturing the activities performed in each zone. Using the historic geo-tagged tweets of users in Washington, D.C. and in Madison, Wisconsin, the results reveal that: 1) M-DBSCAN can capture dispersed clusters with low density of points, and therefore detecting more activity zones for each user; 2) A value of 40 m or higher should be used for eps to reduce the possibility of collapsing distinctive activity zones; and 3) A value between 200 and 300 m is recommended for eps while using DBSCAN for detecting activity zones.     

1956-2018年中国江河径流演变及其变化特征

地表水资源是维系区域生态平衡和促进经济社会发展的制约性要素,河川径流是地表水资源的主要形式,二者的丰枯变化均直接影响流域水资源管理。基于江河实测径流量资料和水资源公报资料,初步分析了1956—2018年中国主要江河实测径流量和中国十大水资源区地表水资源的变化和演变特征。结果表明:①除长江大通站外,中国主要江河代表性水文站实测年径流量均呈现下降趋势。②黄河上游唐乃亥站实测年径流量为非显著性减少趋势,黄河花园口站实测径流量呈现显著性减少趋势;1980—2000年和2001—2018年唐乃亥站实测径流量较基准期1956—1979年分别变化1.8%和-5.9%,而同时期花园口站实测径流量分别减少26.7%和41.0%。③地理分布上,黄河是中国南北地区径流变化的分水岭,黄河以南地区江河径流量为非显著性变化,黄河以北江河径流量为显著性减少趋势,特别是海河流域,实测径流量减少最为显著;21世纪以来,黄河以北河流实测径流量较1980年之前减少幅度超过25%,海河减幅高达80%以上。④1956—2018年全国地表水资源量约为27266亿m 3,较第二次全国水资源评价结果偏少122亿m 3。21世纪以来,海河、黄河、辽河地表水资源明显减少,进一步加重了区域水资源供需矛盾。     

堰塞坝漫顶溃决过程溃口纵向下切与溯源

为进一步了解堰塞坝溃坝过程,开展了9组水槽模型试验,对溃口纵向下切和溯源发展过程进行了系统分析,并讨论了上溯源点移动速度与溃口水深之间的关系。研究发现：非黏性堰塞坝溃坝过程中,冲刷面与底床的夹角时刻发生变化,上、下溯源点位置不固定但也不能完全发展到坝踵;上、下坡面坡度增大到最大值1：1.5时,下溯源点到下游坝趾的最大距离与坝体沿水流方向长度的比值（x_p^*/x_d^*,反映下溯源点最终相对位置）对应降低到最小值0.24和0.18;坝体相对尺寸从1减小到1/2时,x_p^*/x_d^*值从0.38增大到0.47。上溯源点的无量纲移动速度是不断变化的,在无量纲时刻为0.13时,其x,y分量分别达到峰值0.94和0.32;上溯源点处溃口水深出现时刻相对移动速度峰值点出现时刻有延迟,大概延迟0.04个无量纲时间。     

三门湾主要经济贝类胃含物中微、小型藻类组成

本文对采自三门湾泥滩、沙滩、岩礁潮间带的主要经济贝类彩虹明樱蛤、缢蛏、僧帽牡蛎、青蚶、光滑河篮蛤胃含物中的微、小型藻类组成进行了鉴定分析。结果表明, 5种经济贝类胃含物中共鉴定出微、小型藻类143种,其中,硅藻占75.5%;甲藻占12.6%;绿藻门和金藻门占5.6%;蓝藻门和隐藻占4.2%;其他类占2.1%。胃含物中出现的细胞个体中,小于20μm的主要微型藻类是中肋骨条藻、盔状舟形藻、尤氏直链藻、小环藻、海链藻等;细胞个体大于20μm的主要小型藻类是琼氏圆筛藻、海生斑条藻、短柄曲壳藻、钝角齿状藻等。