Techniques for assessing spatial heterogeneity of carbonate δ13C values: Implications for craton‐wide isotope gradients

The sedimentary record of carbonate carbon isotopes (δ¹³C_carb) provides one of the best methods for correlating marine strata and understanding the long‐term evolution of the global carbon cycle. This work focuses on the Late Ordovician Guttenberg isotopic carbon excursion, a ca 2·5‰ positive δ¹³C_carb excursion that is found in strata globally. Substantial variability in the apparent magnitude and stratigraphic morphology of the Guttenberg excursion at different localities has hampered high‐resolution correlations and led to divergent reconstructions of ocean chemistry and the biogeochemical carbon cycle. This work investigates the magnitude, spatial scale and sources of isotopic variability of the Guttenberg excursion in two sections from Missouri, USA. Centimetre‐scale isotope transects revealed variations in δ¹³C_carb and δ¹⁸O_carb greater than 2‰ across individual beds. Linear δ¹³C_carb to δ¹⁸O_carb mixing lines, together with petrographic and elemental abundance data, demonstrate that much of the isotopic scatter in single beds is due to mixing of isotopically distinct components. These patterns facilitated objective sample screening to determine the ‘least‐altered’ data. A δ¹⁸O_carb filter based on empirical δ¹⁸O_carb values of well‐preserved carbonate mudstones allowed further sample discrimination. The resulting ‘least‐altered’ δ¹³C_carb profile improves the understanding of regional as well as continental‐scale stratigraphic relations in this interval. Correlations with other Laurentian sections strongly suggest that: (i) small‐scale variability in Guttenberg excursion δ¹³C_carb values may result in part from local diagenetic overprinting; (ii) peak‐Guttenberg excursion δ¹³C_carb values of the Midcontinent are not distinct from their Taconic equivalents; and (iii) no primary continental‐scale spatial gradient in δ¹³C_carb (for example, arising from chemically distinct ‘aquafacies’) is required during Guttenberg excursion‐time. This study demonstrates the importance of detailed petrographic and geochemical screening of samples to be used for δ¹³C_carb chemostratigraphy and for enhancing understanding of epeiric ocean chemistry.     

Some age measurements on micas from broken hill,Australia

K‐Ar measurements were carried out on 24 mineral concentrates, mostly biotite, from rocks in the Broken Hill district of New South Wales; Rb‐Sr measurements were carried out for comparison on eight of these. The results range from 430 to 1360 m.y. for K‐Ar, and from 460 to 550 m.y. for Rb‐Sr. They indicate that the last event of sufficient intensity to affect the biotites of this area occurred in the Lower Palaeozoic. This may be correlated, as a first hypothesis, with the event which caused emplacement of the secondary “Thackaringa‐type” lead deposits.     

Evaluation of In Situ Heterogeneity of Elements in Solids: Implications for Analytical Geochemistry

A general method for the evaluation of in situ heterogeneity of geochemical materials is described and the significance of the results discussed, by using three case studies and earlier data sets. The heterogeneity of Pb in soil (expressed as RSD due to sampling, RSD_samp) varies from < 5 to > 100% between different sites, in a way that relates to the mode of deposition of the element. The heterogeneity of an element also varies systematically as a function of the distance scale at some sites. This variation can be modelled using linear regression, accounting for over 90% of the experimental variance, at seven scales over three orders of magnitude. Variation in heterogeneity between elements at the same site, seems to be somewhat diagnostic of the origin of the element, lithogenic being less than anthropogenic, although the later is also being modified by the mode of deposition. Where the heterogeneity is large (RSD > 30%), it is proposed that it can be expressed more accurately as a heterogeneity factor (10^GSDsamp), to reflect its frequency distribution, which is positively skewed towards higher concentration values.     

中国森林乡村的多尺度分异特征与分区优化

国家森林乡村建设是实施乡村振兴战略和改善农村人居环境的重要措施,但森林乡村在不同尺度的分异特征及优化方向尚不明晰。本文综合运用探索性空间数据分析、耦合度模型和Voronoi图分析等研究方法,从全国、区域和行政尺度分析了国家森林乡村空间格局、数量规模和内部分异特征,并基于森林乡村与人口耦合关系及乡村可达类型识别,分析了全国森林乡村的分区格局及其优化方向。结果表明：全国森林乡村密度具有明显的东高西低分异特征,长江三角洲地区是森林乡村高密度集中分布最大的连片区。基于县域单元的省域森林乡村泰尔指数差异较大,东南区域森林乡村分布相对均衡,西南和东北区域内部差异显著。森林乡村空间可达性呈现自东向西的梯度递减,森林乡村与人口密度的耦合类型分布具有较强的内部分异性。文章基于森林乡村可达类型与耦合分区的组合分析,将全国划分为重点发展区、特色挖掘区、集聚提升区、适度引导区和功能转型区五类,明确了不同类型区森林乡村建设的重点方向,将为面向乡村振兴的全国森林乡村建设与分区优化提供决策依据。     

叶面积指数遥感尺度效应与尺度纠正

由于地表空间异质性的普遍存在,遥感反演模型的非线性必然会导致不同分辨率观测的遥感结果不一致,从而产生遥感产品尺度效应。本文研究了遥感产品尺度效应概念、模拟方法和定量计算模型,并利用锡林浩特草原研究区的实测数据,对尺度效应模型和方法进行了定量计算与验证分析。首先,基于不同升尺度方法与多尺度遥感成像机理之间的机理联系,通过“先反演再平均”与“先平均再反演”之间的差异,可计算“高”分辨率与“低”分辨率之间的遥感产品尺度差异。其次,分别以红光、近红外两波段反射率和归一化植被指数(NDVI)为自变量,对叶面积指数(LAI)非线性遥感模型进行泰勒展开,研究了模型非线性、遥感数据空间异质性对LAI遥感产品尺度差异的影响,发现高阶项可忽略,利用二阶导数项和遥感数据方差项可定量计算遥感产品尺度差异,经过二阶导数项纠正后的尺度差异相对偏差从5.6%分别降低到0.78%和1.45%。最后,分析了LAI遥感产品尺度效应的特征规律,得出以下结论:随着植被覆盖的增大,同等遥感空间异质性的LAI遥感产品尺度差异越大,且红光波段比近红外波段的尺度差异敏感性高近2个数量级;对于绝大部分陆地植被区域,存在“低分辨率低估”尺度效应,且遥感产品尺度差异的主导要素为LAI模型非线性,NDVI变量自身非线性对尺度效应贡献占23.5%;对于湿地类植被与水体混合情形,NDVI变量非线性的贡献为主导贡献,出现“低分辨率高估”尺度效应,必须利用红光、近红外两波段的二阶导数项非线性尺度差异,才能解释这一类型的LAI遥感产品尺度效应。本文建立了具有一定普适意义的遥感产品尺度效应定量模拟与尺度纠正方法,对推动定量遥感的尺度问题研究有一定参考价值。     

青海高原西宁城镇社区家庭能耗直接碳排放研究

选取青海高原城市西宁为研究对象,开展家庭能源消费问卷入户调查,建立高原城市家庭能源消费数据库(N=500),采用探索性空间数据分析方法,总结分析家庭能耗碳排放的空间特征与驱动因素,得出以下结论：(1)西宁市家庭人均能源消费量与人均能耗碳排放平均值分别为10.57 kgce/d和6.11 kg/d,取暖、厨房设备及热水器设备是家庭能耗及碳排放的主要来源;(2)西宁市人均家庭能源消费碳排放总体呈现出高值区(HH)、低值区(LL)相对集聚,而局部地区也存在高低值区(HL)和低高值区(LH)集聚现象,其空间规律呈现明显的异质性;(3)家庭收入、地理环境以及建筑特征等因素是人均家庭能源消费碳排放空间异质性形成的主要因素。     

海南自贸港金融服务实体经济效率的时空异质性及其驱动机理

提升金融服务实体经济效率是海南自贸港建设亟待研究和突破的“靶点”。论文通过测算2011—2020年海南自贸港18市县金融服务实体经济效率,利用Dagum基尼系数与Kernel密度估计方法刻画效率的时空异质性,并借助随机森林模型揭示其驱动机理,创新性地从时空视角挖掘海南自贸港金融服务实体经济效率分异机制。研究发现：(1)海南自贸港金融服务实体经济效率时空非平衡性明显,时序上阶段性显著,空间上呈西高东低、高值聚集、中部“洼地”的分布特征,西北部市县与中部市县各自逐步形成高值、低值聚集区;(2)总体及沿海市县梯度分化特征逐步加强,而非沿海市县内部差距则逐步缩小,沿海区域金融服务实体经济效率的空间分异是总体分异的主要来源;(3)政府干预是效率分化的主导因素,含金融集聚度在内的影响因素对效率均呈非线性影响且作用趋势与阈值各异,各因素的边际产出能力及各市县对要素的吸收与应用能力的动态差异是时空异质性的主要来源。研究结论可为优化海南自贸港金融资源的空间配置、提升金融服务实体经济效率提供科学依据。     

Spatial distribution and the scale effect of influencing factors of specialized and sophisticated enterprises that produce new and unique products in the Yangtze River Delta region: Based on the buffer and MGWR analyses北大核心CSCD

High-quality cultivation of specialized and sophisticated enterprises that produce new and unique products is an important starting point for consolidating the security foundation of China's industrial chain and supply chain. Using buffer zone analysis and the multi-scale geographically weighted regression (MGWR) model, this study explored the spatial distribution of specialized and sophisticated enterprises that produce new and unique products in the Yangtze River Delta region and influencing factors in 2021. The study found that: 1) Spatially, Shanghai is the main area where specialized and sophisticated enterprises that produce new and unique products are concentrated, followed by provincial capitals and cities on the coast and along rivers; The overall composition of the industry is unbalanced, and the real economic industries such as machinery and equipment manufacturing and high-tech manufacturing account for a relatively high proportion, but there are differences in different regions. 2) In terms of spatial agglomeration, differences between circles and the scale effect are obvious. Within each province, the spatial distribution of specialized and sophisticated enterprises that produce new and unique products in different cities is uneven. Region-wide, the overall spatial distribution pattern of "one pole and multiple cores" is evident. Shanghai is the main agglomeration area for these enterprises, and the provincial capital cities and cities that are the regional economic centers are the secondary agglomeration areas of these enterprises. 3) The four dimensions of influencing factors—physical geography, government, market, and society—have a scale effect on the spatial distribution of specialized and sophisticated enterprises that produce new and unique products. The degree of land development acts at a small scale, which is a local variable, and shows a large difference in the impact on the spatial distribution of these enterprises across the region. Factors such as elevation, government-business relationship, degree of marketization, number and scale of enterprises, degree of openness, logistics development level, and innovation environment are global variables, and except that the degree of marketization and the number of enterprises have a significant negative impact on the spatial distribution of these enterprises, the impact of all other factors is significantly positive. The research results can provide support for the optimization of the layout of new special expertise enterprise space in the Yangtze River Delta region, in order to provide reference for the formulation of new special expertise policies and industrial planning. © 2023, Editorial office of PROGRESS IN GEOGRAPHY. All rights reserved.     

地形起伏度最佳分析区域预测模型

地形起伏度指分析区域内最高点和最低点之差,反映宏观区域内地形的起伏特征,是描述地貌形态的定量指标。确定最佳分析区域是地形起伏度提取算法的核心步骤,以及决定地形起伏度提取结果有效性的关键。本文以全国范围内随机选取的78个实验区域、三种不同尺度的DEM数据作为实验对象,分别进行系列分析区域尺度的地形起伏度计算,建立了基于微观地形特征因子的地形起伏度最佳分析区域预测模型。实验表明：相同区域、不同尺度的DEM数据提取的地形起伏度存在差异,DEM尺度相差较小时,地形起伏度的差异也较小;地形起伏度和实验区域的最大高程、区域高差、平均坡度和平均坡度变率等地形特征因子存在强相关关系;当置信水平为0.05时,预测模型拟合参数的准确率达到95%以上,证明预测模型可以有效地确定最佳分析区域的取值范围。     

Neighborhood-Based social capital and life satisfaction: the case of Rotterdam,The Netherlands

ABSTRACT

In this study, we examine the relationship between neighborhood-based social capital and residents’ life satisfaction by considering resident heterogeneity. Using a database of the city of Rotterdam, The Netherlands, we find a small but significant positive association between neighborhood-based social capital and individual life satisfaction. However, we also find considerable differences among residents because neighborhood-based social capital is important mainly for people who are more likely to spend considerable time in the neighborhood or who are more neighborhood dependent (i.e. less-educated people, people who live on welfare, people with poor health, retired people, and those who are divorced or widowed). Our results confirm the importance of neighborhood-based social capital for residents’ life satisfaction in terms of both actual social contacts with neighbors and the perceived social cohesion within a neighborhood. At the same time, the importance of neighborhood-based social capital varies among different groups of residents. These findings have important implications for policy-makers.