山西襄汾农田土壤磁化率和养分空间变异性

应用地统计学方法研究了山西省西南部襄汾县农田土壤的环境磁学和养分特征。结果表明:土壤低频磁化率、高频磁化率、频率磁化率、pH值、有机质、全氮和全钾平均含量分别为92.54×10-8 m3·kg-1、86.93×10-8 m3·kg-1、6.03%、8.26、1.94%、1.02 g·kg-1和2.39%;变异函数分析显示,土壤低频磁化率的空间相关距离最大为14.33 km,说明在一个较大的距离范围内存在空间相关性;块金系数比为23.41%,说明土壤磁化率主要取决于土壤母质、土壤性质、地形等结构因素。耕作和施肥等人为活动虽对土壤磁化率有一定的影响,但未改变其原有空间结构。本结果揭示土壤磁化率和养分的空间分布规律,为农田土壤环境质量评价和管理提供重要依据。     

中国工业中小企业省区分布及其影响因素

20 世纪90 年代乡镇企业改革以来,中国中小企业空间格局发生了显著变化。现有地理学文献主要关注中小企业空间集聚、集群研究以及八九十年代的中小企业空间分布问题,对于近20 年来宏观层面中小企业空间分布的研究比较薄弱,实证研究尤为缺乏。基于文献回顾,运用GIS 空间分析、测算变差系数CV等方法,分析1997-2010 年中国工业中小企业省区分布的时空格局变化;在此基础上,选取20 个影响因素并建立计量模型,运用SPSS及Eviews软件,系统测算导致中国工业中小企业省区分布变化的影响因素,并根据研究结果提出相关政策建议。研究表明：① 1997-2010 年间,中国工业中小企业的省区分布更加集中、空间差异不断扩大;② 中国工业中小企业省区分布格局是多因素综合作用的结果,其中地区经济实力、金融环境、市场环境及技术创新是首要因素,信息化、劳动力、铁路密度及农业资源是次要因素。     

华南冬春降水的年际变化及其与水汽输送的联系

利用1960—2008 年华南47 个基准站降水资料和NCEP/NCAR 再分析资料,研究了华南冬春降水的年际变化特征及其与水汽输送的联系。结果表明,1960 年代—1970 年代和1990 年代末至今,华南冬、春降水明显偏少。华南冬春降水异常以“ 全区冬春同号型” 居多,且冬春连旱频率较高。影响华南冬春连续旱/涝的水汽输送存在季节性差异,冬季水汽输送变化主要来源于孟加拉湾和南海,春季水汽输送变化则来源于南海和我国北方。进一步探讨海温异常的影响发现,与华南冬春连续旱(涝)事件相关的Niño3.4 海温存在正、负异常型,海温异常中心分别偏向Niño4(Niño3)区和Niño3(Niño4)区。Niño3.4 区海温正异常时,孟加拉湾和南海水汽输送与华南冬春连续旱涝有密切联系;Niño3.4 区海温负异常时,冬季自西北太平洋经南海的水汽输送及春季自菲律宾海经南海的水汽输送和北方水汽输送对华南冬春连续旱涝有重要影响。以上水汽输送在两种海温异常情况下,连涝(旱)年均异常偏强(弱)。因此,Niño3.4 海温异常的变化及分布与华南冬春持续旱/涝事件存在联系,在此气候背景下,水汽输送异常是影响华南冬春降水异常的重要物理因子,其中南海是水汽输送异常显著相关区。      

Quantifying the Spatial Characteristics of the Moisture Transport Affecting Precipitation Seasonality and Recycling Variability in Central Asia

Moisture contribution and transport pathways for Central Asia(CA)are quantitatively examined using the Lagrangian water cycle model based on reanalysis and observational data to explain the precipitation seasonality and the moisture transport variation during 1979-2015.Westerly-related(northwesterly and westerly)transport explains 42%of CA precipitation and dominates in southwest CA,where precipitation is greatest in the cold season.Southeast CA,including part of Northwest China,experiences its maximum precipitation in the warm season and is solely dominated by southerly transport,which explains about 48%of CA precipitation.The remaining 10%of CA precipitation is explained by northerly transport,which steadily impacts north CA and causes a maximum in precipitation in the warm season.Most CA areas are exposed to seasonally varying moisture transport,except for southeast and north CA,which are impacted by southerly and northerly transport year-round.In general,the midlatitude westerlies-driven transport and the Indian monsoon-driven southerly-related transport explain most of the spatial differences in precipitation seasonality over CA.Moreover,the contribution ratio of local evaporation in CA to precipitation exhibits significant interdecadal variability and a meridionally oriented tripole of moisture transport anomalies.Since the early 2000s,CA has experienced a decade of anomalously low local moisture contribution,which seems jointly determined by the weakened moisture contribution from midlatitudes(the Atlantic,Europe,and CA itself)and the enhanced contribution from high latitudes(West Siberia and the Arctic)and tropical areas(South Asia and the Indian Ocean).     

Variability and management patterns of range resources in the Baro River plain, Ethiopia

The biophysical environment of rangelands in the arid and semi-arid lowland parts of Africa is customarily viewed as a homogenous entity. Such notion has encouraged employing a blanket management approach. However, there are perceptible variations within them which necessitate site-specific range management. This study has attempted to identify the variability of soil and forage attributes and assess the existing management practices of those resources in the Baro River plain, Ethiopia. Sample transects, representing pre- and post-fire conditions, were used to collect composite soil samples and vegetation attributes. Alongside the physical survey, a household survey was undertaken to validate the laboratory-generated information. The result showed significant differences of soil and forage attributes among different management regimes, distances from river course and dominant cover types. In general, the distribution of soil nutrients showed a 'distance decay effect', while the distribution of pH showed the reverse pattern. Application of heavy fire load and congested grazing are the principal range management related factors. About 80 per cent of sample pastoralists employ heavy fire without due consideration for the sustainability of the range resource and without considering the local variability. Recognition of site-specific information is the key to effective management of range resources in the study area.     

犯罪热点时空分布研究方法综述

犯罪在地理时空内并不是均匀分布的,而是表现出明显的时空聚集特性,这种聚集性常用“犯罪热点”表述.基于对犯罪热点的理解,从犯罪热点时空分布模式、犯罪热点成因分析以及犯罪热点时空转移及预测等3 个方面总结了当前国内外犯罪热点时空分布相关研究方法的进展.最后,对该领域研究进行了总结与展望.总体上,国内相关研究较少,尚需进一步结合中国国情,提出适用方法.另外,也需要通过相关犯罪理论的深入研究以及其他领域研究方法的借鉴,实现犯罪热点时空分布研究方法的突破与创新.     

珠江口西部海域表层沉积物重金属元素多尺度空间变化特征

笔者应用因子克里格分析方法,研究了珠江口西部海域388个表层沉积物中7种重金属元素Cd, Ni,Cu,Zn,Pb,Cr和As的空间结构特征,识别并分离了重金属元素不同尺度的空间主成分及其分布特征,探讨了不同空间尺度重金属的物源及控制因素。结果显示,研究区7种重金属元素在空间上存在块金尺度、局部尺度(变程为60 km的球状结构)和区域尺度(变程为160 km的球状结构)3种尺度的空间变化。以迭代算法模拟了研究区重金属元素线性协同区域化模型。根据不同尺度上区域化因子的主成分得分分布特征可知:局部尺度上,F₁因子(Zn,Cr,Ni,Cu)和F₂因子(As)的高值区表现为"牛眼"状局部特征,并分布在陆地沿海的河口或者港湾区,指示了可能受人为污染成分影响的重金属区域。其中,雷州半岛东部沿海是最可能的重金属污染区,其空间分布主要受控于局部的地形、海流等因素。F₂因子不同于F₁的空间分布,主要在于As不同于Zn,Cr,Ni,Cu等的地球化学行为。区域尺度上,F₁(Zn,Cr,Ni)和F₂(As)因子主要反映了不同陆源母岩物质的影响。Zn,Cr,Ni等主要源于华南大陆陆源母岩物质,而As主要受到海南岛陆源母岩物质的控制。F₁和F₂因子得分高值区整体上表现为NNE向自陆地向较深海域延伸的"片状"分布特征,推测其主要受到海平面变化及NNE向区域性海洋环流的控制。     

Guidelines for sampling bedload transport with minimum uncertainty

The stability of river channels and their suitability as habitat for aqueous organisms is strongly controlled by the rate of bedload transport. Quantification of bedload transport rates in rivers is difficult, not only because of the temporal variation in transport, but also because of the cross‐channel variation in transport. The objectives of this study were: (i) to determine the effect of cross‐channel variation in bedload transport on the uncertainty of width‐integrated transport rates; and to use this knowledge (ii) to improve guidelines for bedload sampling. This was done through a thorough statistical evaluation of stochastic and systematic uncertainties involved in bed‐load transport measurements. Based on this evaluation, new guidelines are presented for determination of the number of samples and sampling positions across the channel that are required for bedload measurements in several types of sand‐bed rivers and gravel‐bed rivers. The guidelines relate to bedload measurements made with pressure‐difference (Helley‐Smith type) samplers that require numerous bedload samples of short duration at several positions across the channel. The results show that generally more sampling positions across the channel are required in gravel‐bed rivers than in sand‐bed rivers. For gravel‐bed rivers with unknown cross‐channel distribution of transport, at least 10 sampling positions are recommended, whereas for most sand‐bed rivers five positions suffice. In addition, at least 12 short‐duration samples are required at each position to obtain bedload estimates with uncertainties below 20%. If the same level of uncertainty is desired in the case of high spatial and temporal variation in transport rates, the number of short‐duration samples needed per sampling position increases to 40.     

智慧城市时空信息云平台评价指标体系研究

为明确评估在开展智慧城市时空信息云平台建设过程中城市相关智能化能力的保障水平及建设带来的实际成效,以及为开展智慧城市建设工作提供依据,本文依据《国家智慧城市评价指标体系》及其对部门评价指标建立的要求,研究并提出了智慧城市时空信息云平台建设评价指标体系的总体框架和评价要素,在试点城市进行了评分试验;并根据试验结果进行了指标的修订和完善,以引导和推动城市有目的、有计划、有步骤地开展智慧城市时空信息云平台建设。