山地城市边缘土地利用格局与变化的地形梯度分布特征分析——以重庆市巴南区为例

地形作为重要的自然基底因子,在很大程度上影响土地利用变化与空间格局形成。以重庆市巴南区为例,借助GIS和RS手段,利用Landsat TM遥感数据和DEM数据,采用地形位指数、分布指数和土地利用程度综合指数等计算方法,对巴南区2000、2010和2015年土地利用格局与变化的地形梯度分布特征进行了分析,探讨了土地利用格局与变化和地形梯度的相互关系,以期为相似地形条件下的山地城市边缘区的人地关系研究提供支撑或参考。研究结果表明：（1）巴南区土地以中、高级地形位为主,海拔200 m以下,坡度8°以下的土地资源较为匮乏;（2）研究期内,中、低级地形位区间内大量耕地转变为建设用地,土地分布结构变化导致二者的分布优势区间均向更高级地形位区间转移;（3）土地利用程度综合指数曲线呈倒“V”型,波峰逐渐向中级地形位区间移动,可以印证在研究期内巴南区低丘缓坡区域内土地利用强度逐渐提升。     

云南喀斯特关键带植被时空变化特征及气候与人为影响因子解析

受自然环境及人类活动的影响,滇东南喀斯特地区石漠化问题严重,当地生态环境面临巨大压力.基于MODIS-NDVI数据通过像元二分模型提取植被覆盖度FVC,采用回归与残差分析等方法对2000 ～ 2016年植被覆盖时空变化特征和趋势进行了分析,并对影响其变化的气候和人为因子进行了解析.研究结果表明:近17年研究区FVC总体呈波动上升的趋势,增长速率为春季(0.005 0/a)＞冬季(0.004 3/a)＞秋季(0.004 0/a)＞夏季(0.000 3/a),年增长速率0.003 6/a.2000年以来FVC呈增加趋势的区域占研究区总面积比例在85％以上,而在市域、县域中心区以减少为主.研究区分别有56.41％、61.47％的FVC与气温、降水因子的相关系数通过0.05的显著性检验,主要呈正相关关系.2000～2016年研究区受人类活动影响持续增加的面积占总面积80.54％,持续减弱的面积占13％,影响不变的面积占6.46％,人类活动对FVC变化的影响呈持续加强的趋势.研究结果将为定量评估喀斯特区域石漠化综合治理工程和生态修复评估提供科学依据.     

长江口溢油数值模拟及对水源地影响

首先建立了一套基于非结构网格的长江口-杭州湾二维垂向平均潮流数学模型,又基于最新的实测资料重点对南支水域流速、流向和水位进行验证,充分证实了模型的可靠性。在潮流模型可靠的基础上为MIKE21 SA(溢油模块)提供水动力基础数据,建立了一套基于欧拉 拉格朗日体系的“油粒子”追踪技术,综合考虑油膜扩展、输移和风化过程的长江口溢油行为与归宿预测模型。并对长江口夏季和冬季大潮溢油事故发生后取水口油膜厚度的变化及油膜运动路径进行了模拟预测。研究表明：油膜在长江口受到往复流形式的涨落潮交替作用,油膜沿深槽向下游震荡漂移;〖JP2〗油膜在纵向上逐渐被拉伸,形成窄长的油带,覆盖面积逐渐增大;油膜的运动轨迹除了受到涨落潮流的主控外还易受风况和长江口水下地形等影响;夏季溢油对3个水库均有不同程度的影响,冬季溢油只威胁到陈行水库的取水;夏季油膜蒸发量大于冬季     

近15年来长江口控制站徐六泾悬沙变化特征研究

基于近15年的实测数据,分析给出了长江河口控制站徐六泾悬沙浓度和组成的变化特性。研究表明：徐六泾站多年平均表层（2003～2017年）、中层和底层（2010～2017年）含沙量分别为0.07、0.07和0.13 g/L;表层（2004～2017年）、中层和底层（2009～2017年）的中值粒径分别为7.3、9.4和11.0 μm。研究期间,年平均含沙量呈显著下降趋势,洪季较枯季降幅更明显。其中2015～2017年均洪枯季表层含沙量较2003～2005年均值分别降低了57%和20%;表层含沙量在2008年出现明显降低的拐点,2008年之后的洪枯季表层含沙量较之前分别降低56%和44%。悬沙粒度具有一定的波动变化,但没有显著趋势性变化特征,或与样本数量限制和流域内人类活动有关。     

川滇农牧交错区地形特征对土地利用空间格局的影响

川滇农牧交错区位于我国青藏高原的东南缘,地形地貌特征复杂,研究该区土地利用特征与地形之间的关系,有助于了解人类开发活动与自然地理条件之间的关系,对区域的资源开发和生态保护具有重要的现实意义。基于RS＼GIS技术,采用遥感调查、土地利用结构分析和GIS空间分析方法,研究了该区 1988～2000年的土地利用特征,以及不同土地利用类型的空间分布与地形因子之间的关系。初步结果发现：耕地、林地和草地是研究区内受人类活动影响的主要土地类型,也是类型转换相对频繁的土地类型;地形因子对不同土地利用类型的空间分布具有显著影响,其中,海拔在垂直方向上对土地利用空间布局具有控制性作用。研究结果同时表明,地形特征是川滇农牧交错区土地利用空间格局形成的基础,其原因在于地形因子通过影响水热条件及其他自然资源要素在本区内的再分配,进而影响着人类对土地资源的利用方式和利用程度.     

2006年特大枯水期间长江中下游河床沙与悬沙沿程变化特征

基于2006年10月长江中下游沿程不同断面的河床沙、悬沙以及流速等相关水文泥沙现场观测资料,采用数理统计学与泥沙运动力学相结合的方法,对极端气候与流域重大工程作用下,长江中下游水沙的沿程变化以及悬沙与河床沙交换等进行分析.流量自宜昌向下游方向总的趋势是沿程增大,观测时段与多年同期平均流量(33 500 m3/s)相比少了近57%,而在沙市河段流速最大值达1.1 m/s;近底层水体含沙量较低,平均值为0.079 kg/m3,与多年平均(50年)含沙量相比减少了90%.大通站实测悬沙含量与多年10月平均相比减少了近86%;河床沙组成以细砂和中砂为主,悬沙组成以粘土和粉砂类为主.与多年平均值相比,河床沙变化并不大,悬沙显著细化.中游河段河床沙中略细的粘土和细粉砂组分含量较上下游为多,而悬沙中略粗的中粗粉砂组分含量较上下游为多,断面垂向差异大;同时,从水流、含沙量、河床沙和悬沙颗粒组成及河道类型等多因素同步分析,表明长江中游河道泥沙交换相对频繁,河床稳定性相对较差,下游河道泥沙交换相对较少,河床稳定性相对较好.     

基于安徽省土地利用变化的地形梯度效应分析

为揭示地形因素与土地利用空间格局演变的关系,以安徽省2000年、2005年以及2010年Landsat TM影像和DEM数据为数据源,利用坡向、地形起伏度、坡度变率和地形位指数多种地形因子,并结合地学信息图谱分析理论从综合角度系统研究土地利用结构时空分异格局在地形梯度上的变化特点及其规律。结果表明:1)研究区主要的土地利用类型是耕地和林地,其次是建设用地和未利用土地,且建设用地面积逐期增加趋势显著。2)2000~2010年研究区不同土地利用类型在不同地形梯度区间的分异规律存在明显差异。低地形梯度范围是耕地、水域和建设用地的优势分布区;中地形梯度范围是草地的集中分布区;林地的优势分布区集中在高地形梯度范围。3)2000~2010年研究区土地利用图谱以稳定型和后期变化型为主,低地形梯度和高地形梯度是稳定型图谱的集中分布区,中低、中高和高地形梯度范围是后期变化型图谱的优势分布区。2000~2005年林地的优势分布区有向较低地形位梯度扩张的趋势,其中,耕地是主要的转入来源。2005~2010年耕地的优势分布区有向较高地形位梯度扩张的趋势,变化模式主要为:"林地–耕地"、"未利用地–耕地"和"草地–耕地"。     

杭州湾南岸滨海平原土地利用/覆被空间格局变化分析

杭州湾南岸滨海平原位于沪、杭、甬经济金三角的中心地带,是我国沿海经济最发达的地区之一。研究其土地利用/覆被空间格局变化对合理利用土地资源,促进沿海地区的可持续发展具有重要意义。利用1987年和2000年2个时期的TM影像,分析了杭州湾南岸滨海平原土地利用/覆被数量及空间格局变化特征。结果表明,杭州湾南岸滨海平原建设用地、水体和养殖用地呈现明显的增长趋势,水田、旱地、滩地、林地和盐田呈减少趋势。受自然和人类活动的共同影响,土地利用/覆被类型斑块平均面积由0.245 km2降至0.173 km2,斑块密度则由4.081个/km2提高到5.781个/km2,斑块数量增加了42%。由于斑块的破碎化,大部分土地利用/覆被类型的边界密度、形态指数、分维数和斑块密度都有不同程度的增加。城市化和非农化的发展使得建设用地格局指数变化表现出一定的特殊性。     

长江口南支邻近水域碎波带仔稚鱼群落结构的差异及关联

为探明长江口南支及邻近水域碎波带仔稚鱼群落结构的差异及相互联系,分别对长江口南支、杭州湾北岸与泗礁沙滩碎波带进行小型拖网（1 m×4 m,网目1 mm）取样调查,样品在实验室内进行种类鉴定及数量统计。结果显示：种类组成方面,3处水域分别采集到仔稚鱼11科40种、23科59种与28科46种,共有种7种;洄游性种类、河口性种类与海洋性种类分别为3者优势类群;单位捕捞努力量渔获量（CPUE）长江口南支最高,为41.45 ind./haul,泗礁沙滩最低,为5.72 ind./haul;长江口南支仔稚鱼各发育阶段个体分布相对均匀,杭州湾北岸以稚鱼个体为主,泗礁沙滩以后弯曲期仔鱼占优势;多样性指数杭州湾北岸最高,为2.19,泗礁沙滩最低,为1.75;长江口南支与杭州湾北岸群落相似度较高。数量变动方面,3处水域种类数均为8月最高,CPUE分别于8月、9月与5月达到峰值。生境功能方面,长江口南支兼具定居地、保育场与暂居地等功能,杭州湾北岸与泗礁沙滩则仅为保育场与暂居地;3处水域共有种中国花鲈（Lateolabrax maculatus）分别在不同时间段及不同发育阶段进入3处水域栖息保育,长江口南支及其邻近水域碎波带是其向岸及溯河洄游过程中的重要保育场与中转站。 关键词： 长江口南支;邻近水域;碎波带;仔稚鱼;群落;差异与关联     

基于SPOT_NDVI的甘肃省植被覆盖变化及其与气候、地形因子的关系

植被覆盖时间序列特征体现了气候变化和人类活动对环境的影响,利用2000~2018年SPOT_NDVI并结合气象和地形数据,采用趋势分析、偏相关分析、地形面积修正等方法探究甘肃省植被覆盖的变化特征及与气候、地形的关系。研究表明：近19年来,甘肃省植被覆盖整体呈恢复状态,但低覆盖区面积仍为最大,空间分布总体呈现南高北低的状态。降水对省内植被生长总体起到促进作用,特别是黄土高原地区,植被覆盖度与降水有显著的正相关性;在南部湿润区和北部干旱区,气温对植被生长分别起到促进和抑制作用。就地形而言,海拔2 500~3 000 m、坡度大于25°的半阳坡地区最适宜植被生长。进行植被覆盖研究,有利于区域生态建设和持续性发展,同时对人地关系以及经济发展的统筹规划也有重要的理论与实际意义。     

Attributable risk, probability of causation, assigned shares, and uncertainty

Calculations of attributable risks, probabilities of causation, and assigned shares attracted increasing interest recently, particularly since the enactment of the Orphan Drug Act. Although efforts have been limited mostly to radiation as the toxic agent, the concept is general to all toxicants. In this paper, the systematic and random uncertainties in calculations of assigned shares are reviewed globally, and possibilities for their reduction are discussed. In addition, an algebraic study is made of the influence of random uncertainties in the input parameters on the random error of the assigned shares. Three dose-effect functions, appropriate for the low-dose, low-effects regions that are of interest here, are chosen for this investigation, and the algebraic properties of the random errors of the assigned shares are discussed. For shares near 0 and 1, the errors are shown to be small and to depend linearly on the value of the shares; the errors are largest for values of the shares near 50%, that is, in the region of almost equal or equal shares.     

Separation and measurement of thorium, plutonium, americium, uranium and strontium in environmental matrices

A technique for the isolation of thorium (Th), plutonium (Pu), americium (Am), uranium (U) and strontium (Sr) isotopes from various environmental matrices has been adapted from a previously published method specific to water samples (Maxwell, 2006). Separation and isolation of the various elemental fractions from a single sub-sample is possible, thereby eliminating the need for multiple analyses.The technique involves sample dissolution, concentration via calcium phosphate co-precipitation, rapid column extraction using TEVA™, TRU™ and Sr-Spec™ resin cartridges, alpha spectrometry for Th, Pu, U and Am and Cerenkov counting for Sr.Various standard reference materials were analysed and chemical yields are in the range of 70-80% for Th, Am, U and Sr and 50-60% for Pu. Sample sizes of up to 10 L for water, 5 g for dry soil and sediment and 10 g for dry vegetation and seaweed can be processed using this technique.     

Revision and meta-analysis of selected biosphere parameter values for chlorine, iodine, neptunium, radium, radon and uranium

There is a continual supply of new experimental data that are relevant to the assessment of the potential impacts of nuclear fuel waste disposal. In the biosphere, the traditional assessment models are data intensive, and values are needed for several thousand parameters. This is augmented further when measures of central tendency, statistical dispersion, correlations and truncations are required for each parameter to allow probabilistic risk assessment. Recent reviews proposed values for 10-15 key element-specific parameters relevant to (36)Cl, (129)I, (222)Rn, (226)Ra, (237)Np and (238)U, and some highlights from this data update are summarized here. Several parameters for Np are revised downward by more than 10-fold, as is the fish/water concentration ratio for U. Soil solid/liquid partition coefficients, Kd, are revised downward by 10-770-fold for Ra. Specific parameters are discussed in detail, including degassing of I from soil; sorption of Cl in soil; categorization of plant/soil concentration ratios for U, Ra and Np; Rn transfer from soil to indoor air; Rn degassing from surface water; and the Ca dependence of Ra transfers.     

Blood cadmium,mercury, and lead in children: An international comparison of cities in six European countries,and China,Ecuador, and Morocco

Children's blood-lead concentration (B-Pb) is well studied, but little is known about cadmium (B-Cd) and mercury (B-Hg), in particular for central Europe. Such information is necessary for risk assessment and management. Therefore, we here describe and compare B-Pb, B-Cd and B-Hg in children in six European, and three non-European cities, and identify determinants of these exposures. About 50 school children (7–14 years) from each city were recruited (totally 433) in 2007–2008. Interview and questionnaire data were obtained. A blood sample was analyzed: only two laboratories with strict quality control were used. The European cities showed only minor differences for B-Cd (geometric means 0.11–0.17 μg/L) and B-Pb (14–20 μg/L), but larger for B-Hg (0.12–0.94 μg/L). Corresponding means for the non-European countries were 0.21–0.26, 32–71, and 0.3–3.2 μg/L, respectively. For B-Cd in European samples, traffic intensity close to home was a statistically significant determinant, for B-Hg fish consumption and amalgam fillings, and for B-Pb sex (boys higher). This study shows that European city children's B-Cd and B-Pb vary only little between countries; B-Hg differs considerably, due to varying tooth restoration practices and fish intake. Traffic intensity seemed to be a determinant for B-Cd. The metal concentrations were low from a risk perspective but the chosen non-European cities showed higher concentrations than the cities in Europe.     

Distribution of PCBs, HCHs and DDTs, and their ecotoxicological implications in Bay of Bengal, India

Analyses of environmentally persistent pollutants like polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) isomers, and dichlorodiphenyltrichloroethane (DDT) and its metabolites in seawater and sediment samples collected from six locations along the east coast of India were carried out using High-Resolution Gas Chromatograph with High-Resolution Mass Spectrometer (HRGC-HRMS). Sediment and water from Chennai harbour and Cuddalore fishing harbour contained higher concentration of all the compounds. The highest concentration (6570 pg/g dry weight) of total PCB was found in sediment from Chennai harbour followed by sediments sampled in Chennai (opposite to Cooum River mouth) (505 pg/g), Cuddalore fishing harbour (335 pg/g) and Mandapam (251 pg/g). Concentrations in other locations were two orders of magnitude lower than Chennai harbour. A distinct PCB distribution pattern in sediment was observed between harbours and other locations. Greater concentrations of tetra-, penta- and hexachlorobiphenyls were observed in sediments of harbours and opposite to Cooum river mouth, but in other locations lower chlorinated biphenyls (di, tri and tetra-) were more. In seawater, HCH concentration was greater than DDT, but it was quite opposite in sediments. Elevated levels of DDT in sediment were observed only at highly populated urban locations, reflecting the local usage and input of this pesticide. Based on sediment/water quality criteria/guidelines, some coastal locations of the Bay of Bengal could be designated as being polluted by DDTs and gamma-HCH (lindane), but not by PCBs. This investigation reveals the declining trend on the environmental burden of persistent pesticides in Indian marine environment. Data on the organochlorine concentrations found in this survey can be used as reference levels for future POPs monitoring programme.     

Kinetics of the adsorption and desorption of radionuclides of Co, Mn, Cs, Fe, Ag and Cd in freshwater systems: experimental and modelling approaches

The sorption and release kinetics of 54Mn, 58Co, 59Fe, 109Cd, 110mAg and 134Cs by freshwater suspended particles were investigated to better identify the biogeochemical processes involved and to obtain suitable data for improving models describing radionuclide migration in freshwater streams. In order to observe any seasonal variability in the interaction of radionuclides with natural particles, experiments were performed both in winter and in summer during a phytoplanktonic bloom. Two kinetic models are compared in this paper: the "one-step reversible" model, based on the hypothesis that the transfer of radionuclides between water and suspended solids is governed by a reversible reaction, and the "two-successive-step reversible" model, which assumes two distinct types of sites or reactions on the solid phase. The "one-step reversible" model is generally unable to describe properly the exchange kinetics; this result shows that at least two processes are generally involved in radionuclide exchange between water and suspended particles. On the contrary, a model involving the existence of two successive reversible reactions properly simultes both the sorption and release kinetics. The determination of the kinetic coefficients allows quantitative assessment of the relative importance and kinetics of the processes. In particular, it has been shown that, except for Cs and Cd, major fractions of the radionuclides are associated at equilibrium with particulate sites involving strong interactions. The kinetics to reach this equilibrium depend on seasonal conditions, especially for Co and Mn: the transfer of Co and Mn to particulate sites involving strong interactions is much slower in winter. The distribution of the radionuclides between water and particulate sites involving weak interactions also shows seasonal variations for Co, Mn, Fe and Ag: the capacity to associate radionuclides is much higher in summer for Co and Mn, while the inverse tendency is observed for Fe and Ag. For Cs and Cd, no significant seasonal differences were observed.     

Naming,Mourning, and the Work of Earthly Coexistence

Setting out from Jacques Derrida’s assertion that every act of naming is “a foreshadowing of mourning” ([2008. The animal that therefore I am. (M.-L. Mallet, Ed., D. Wills, Trans.). New York, NY: Fordham University Press], p. 20), this paper argues that the work of earthly coexistence is underwritten by the intertwined practices of naming and mourning. The paper demonstrates that names provide access to and shape our perceptions of earthly entities; that the act of naming prepares us for the work of mourning; that the proper names given to endlings provide poignant points of access to species on the edge of extinction; that species names disclose species as such and, thus, enable us to grieve not just particular living organisms but entire ways of life; and that the name given to the current geological epoch, the “anthropocene,” simultaneously reflects and engenders a mode of awareness which enables us to relinquish those ways of being human that no longer seem sustainable and carry forth those that promise to enrich earthly coexistence.     

Crisis,Coherence, and the Promise of Critical Rhetoric

This essay responds to the keynote address by Cox by discussing the ways in which critical rhetoric is implicated in environmental communication (EC) as a crisis discipline, as well as the ways in which EC, so positioned, is implicated within a broader coherentist epistemology. Issues of exigency, representation, and sustainability are considered, along with an examination of the concepts of nominalism and doxa as they relate to the enterprise of EC research. The critical cultural politics embedded in much EC scholarship are also addressed in terms of their intersections with the increasingly unscrupulous abuse of language within antienvironmental administrative rhetorics.