基于多时相主被动遥感的漓江水面监测与水质参数反演(2016-2020年)

以漓江流域为研究区域,以2016-2020年Landsat 8 OLI、GF-1、Sentinel-2A及Sentinel-1A逐月影像为数据源,选用归一化水指数(NDWI)、改进型归一化水指数(MNDWI)、增强型水体指数(EWI)、归一化差值池指数(NDPI)、后向散射系数(S)与主被动遥感加权指数(JQ)提取漓江...     

利用深度学习填补双偏振雷达回波遮挡

广州S波段双偏振天气雷达低仰角多方位存在遮挡,高仰角也存在部分遮挡。基于卷积神经网络等深度学习方法,构建垂直填补（vertical echo-filling,VEF）和水平填补（horizontal echo-filling,HEF）网络架构,基于两种架构,利用无遮挡区的反射率因子ZH、差分反射率ZDR,差传播相移率KDP构建训练集,填补遮挡区的ZH和ZDR。针对仅0.5°仰角存在遮挡的区域,基于VEF架构,利用上层多个仰角、径向、距离库的三维数据,分距离段训练垂直填补模型。针对遮挡仰角较高的区域,则基于HEF架构,利用同一仰角左右相邻的多个径向、距离库的数据,分遮挡径向训练水平填补模型。根据解释方差、平均绝对偏差和相关系数3个指标和3个个例,对模型效果进行评估。结果表明：ZH填补模型的解释方差最大为0.92,平均绝对偏差最小为1.69 dB,相关系数最高为0.96;ZDR填补模型的解释方差最大为0.92,平均绝对偏差最小为0.12 dB,相关系数最高为0.96。利用该研究构建的深度学习填补架构,可有效填补偏振雷达遮挡区域回波,提高雷达数据质量。     

Groundwater pollution containing ammonium,iron and manganese in a riverbank filtration system: Effects of dynamic geochemical conditions and microbial responses

Bench-scale experiments were conducted to investigate the effect of hydraulic loadings and influent concentration on the migration and biotransformation behaviour of three groundwater pollutants: ammonium (NH₄⁺), iron (Fe²⁺) and manganese (Mn²⁺). Columns packed with aquifer media collected from a riverbank filtration (RBF) site in Harbin City, NE China were introduced synthetic groundwater (SGW) or real groundwater (RGW) were at two different constant flow rates and initial contaminant concentrations to determine the impact of system conditions on the fate of the target pollutants biotransformation. The results showed that the biotransformation rate of Fe²⁺ Mn²⁺ and NH₄⁺ decreased by 8%, 39% and 15% under high flow rate (50 L d⁻¹) compared to low flow rate (25 L d⁻¹), which was consistent with the residence-time effect. While the biotransformation rate of Fe²⁺ Mn²⁺ and NH₄⁺ decreased by 7%, 14% and 9% under high influent concentration comparing with original groundwater. The 16S rRNA analysis of the aquifer media at different depths after experiments completion demonstrated that the relative abundance of major functional microbes iron-oxidizing bacteria and manganese-oxidizing bacteria under higher flow rate and higher influent concentration decreased 13%, 14% and 25%, 24%, respectively, whereas the ammonium-oxidizing bacteria and nitrite-oxidizing bacteria exhibited minimal change, compared to the lower flow rate. Above all results indicated that both high flow rate and high concentration inhibit the biotransformation of NH₄⁺, Fe²⁺ and Mn²⁺. The biotransformation of Fe²⁺ and Mn²⁺ occurs primarily in the 0–40 cm and 20–60 cm depth intervals, respectively, whereas the NH₄⁺ biotransformation appears to occur relatively uniformly throughout the whole 110 cm column. The biotransformation kinetics of NH₄⁺ in RGW and SGW, Mn²⁺ in RGW at different depths accords with the first order kinetics model, while Fe²⁺ in RGW and SGW, Mn²⁺ in SGW presented more complicated biotransformation process. The results should improve understanding of the transport and fate of common groundwater pollutants in RBF and other groundwater recharge environments.     

上扬子西缘晚二叠世宣威组凝灰岩： 对峨眉山大火成岩省火山活动及古特提斯弧火山作用的约束

扬子西缘二叠系—三叠系之交凝灰岩的研究对探讨峨眉山大火成岩省及古特提斯周缘岩浆弧火山活动的时限约束具有重要意义。本次工作在上扬子西缘永善地区晚二叠世宣威组中发现多层凝灰岩。对其底部和顶部凝灰岩进行LA- MC- ICP- MS锆石U- Pb测年和Hf同位素研究显示:底部凝灰岩加权平均年龄为258. 9±0. 7 Ma，锆石Th/Nb比值为2. 53~13. 05，εHf(t)值为3. 0~5. 0，TDM2为988~871 Ma；锆石微量元素、Hf同位素及二阶模式年龄显示其具有与峨眉山玄武岩相关的特征，为峨眉山大火成岩省后期产物。顶部凝灰岩加权平均年龄为254. 9±0. 6 Ma，锆石Th/Nb比值为36. 50~311. 85，εHf(t)值为-7. 4~-6. 9，TDM2为1573~1529 Ma；锆石微量元素、Hf同位素及二阶模式年龄特征表明其形成于宋马- 哀牢山- 金沙江构造带弧火山活动。研究表明:宣威组下部凝灰岩为峨眉山大火成岩省后期酸性火山活动的产物，研究区峨眉山火山活动至少持续到了258. 9±0. 7 Ma。古特提斯弧火山作用至少于254. 9±0. 6 Ma就已启动。     

垃圾堆放场氯代脂肪烃对浅层地下水的污染特征初步分析

研究区是浅层地下水主要补给区，通过区内地下水监测说明，受垃圾淋滤液影响的地下水中氯代烃高值点主要集中在研究区中部；地下水中氯代烃检出值和检出率有季节性变化特征，与垃圾堆放时间和该井距垃圾场堆放场距离有密切关系，堆放时间越长，离垃圾堆放场越近，检出率、检出值越高；对地下水污染的敏感性和影响氯代烃迁移的机理方面进行了分析。     

Contribution of glacier melt to sea-level rise since AD 1865: a regionally differentiated calculation

 The contribution of glacier melt, including the Greenland ice-sheet, to sea-level change since AD 1865 is estimated on the basis of modelled sensitivity of glacier mass balance to climate change and historical temperature data. Calculations are done in a regionally differentiated manner to overcome the inhomogeneity of the global distribution of glaciers. A distinction is made between changes in summer temperature and in temperature over the rest of the year. Our best estimate of the ice melt in the period 1865–1990 in terms of sea-level change equivalent is 5.7 cm (2.7 cm for glaciers and 3.0 cm for the Greenland ice-sheet). Additional calculations show that simpler methods, like using annual or even global mean temperature anomaly give estimates that differ by up to 55%. Consequently, a regionally differentiating approach is advised for making projections of glacier melt with GCM output. Received: 6 December 1996/Accepted: 30 May 1997     

江西中生代晚期火山岩区岩石地层划分

江西中生代晚期存在江南、北武夷和赣南三个地层分区,各地层分区的地层特征存在明显区别。根据不整合面和岩石组合特征,结合岩石地层单位“群”与火山旋回或沉积旋回相对应的原则,江南地层分区可划分出火把山群和圭峰群;北武夷地层分区可划分出武夷群、罗塘群和圭峰群;赣南地层分区可划分出余田群、莲花寨群、版石群和圭峰群。根据岩性岩相特征,结合岩石地层单位“组”与火山—沉积复合岩相或沉积岩相相对应的原则,各群可进一步划分为若干个组。     

黄河以北地区东线引江问题的探讨

南水北调东线一期工程1990年完成后,长江之水将被引至黄河南岸的东平湖,设计入东平湖的流量为50立方米/秒^[1]。第一期工程完成后,要不要扩大调水规模,把江水北送过黄河?江水调过黄河以后环境后效如何?引江穿黄与黄河水沙资源利用的关系如何?这些问题关系到南水北调东线第二期工程的规划与最终调水的规模,本文从黄河以北地区的现实情况出发,对几个有关的问题进行了分析。     

情理整合视角下旅游者环境责任行为与 意愿悖离研究——基于Logistic-ISM模型

基于对岳麓山景区447位旅游者的实地调研,运用拓展的计划行为理论并结合Logistic回归模型,分析影响两者发生悖离的因素,并进一步利用ISM解释结构模型分析各因素之间的逻辑关系.从Logistic回归结果看,旅游者的行为态度、感知行为控制等相关理性认知越好,发生悖离的可能性越低;旅游者积极环境情感和消极环境情感对悖离...     

基态修正模型的时空数据组织和快照查询方法研究

基态修正模型是目前应用较广的一种时空数据模型.本文分析了基态修正模型中的时空数据特点,采用shapefile文件作为基态数据文件,自主设计差文件格式来存储和组织变化数据.在此基础上设计了快照查询的算法、流程和查询结果的显示方法.为了给用户提供更直观、更充分的时空信息,本文提出了一种双屏幕多视图的时空数据显示模式.采用VC.NET从底层开发了一个时态地理信息系统平台,并以中南大学主校区的时空数据为实验数据对上述算法和模式进行了检验.实验表明,本文所设计的算法可行,快照显示模式能够提供更直观、更丰富、对比性强的信息内容,是时空信息显示的一种可行模式.