西藏鄂雅错盐湖砷和汞的分布特征研究          下载免费PDF全文

陈嘉琪  王建萍  张耀玲  凌智永 《盐湖研究》2022,30(2):61-69

本研究对西藏鄂雅错盐湖和主要支流中不同形态的砷(亚砷酸盐As(Ⅲ)、砷酸盐As(Ⅴ)、一甲基砷酸MMA、二甲基砷酸DMA)和总汞(THg)含量进行了测定,并与主要水质参数进行相关性分析研究,结果表明鄂雅错盐湖As主要以As(Ⅴ)形态存在,其次分别为As(Ⅲ)、DMA和MMA,其中无机砷的含量明显大于有机砷。相比较其他砷的形态,盐湖中As(Ⅲ)与主要水质参数的相关性显著,与总溶解性固体(TDS)、总溶解态氮(DTN)呈显著的强正相关性,与水温、溶解氧 (DO)、氧化还原电位(Eh)、pH呈显著负相关性。总汞浓度较低,且与主要水质参数相关性不显著。通过风险评价发现鄂雅错湖水中砷存在一定的致癌健康风险,汞不存在风险。本研究丰富了西藏盐湖和支流水体中砷、汞分布特征及其环境影响因素的认识,对于环境保护具有一定的意义。  相似文献   

Are the circular, dark features on Comet Borrelly's surface albedo variations or pits?     

Robert M Nelson  Laurence A Soderblom 《Icarus》2004,167(1):37-44

The highest resolution images of Comet 19P/Borrelly show many dark features which, upon casual inspection, appear to be low albedo markings, but which may also be shadows or other photometric variations caused by a depression in the local topography. In order to distinguish between these two possible interpretations we conducted a photometric analysis of three of the most prominent of these features using six of the highest quality images from the September 22, 2001 Deep Space 1 (DS1) flyby. We find that: 1. The radiance in the darkest parts of each feature increases as phase angle decreases, similarly to the radiance behavior of the higher albedo surrounding terrain. The dark features could be either fully illuminated low albedo spots or, alternatively, they could be depressions. No part of any of the three regions was in full shadow. 2. One of the regions has a radiance profile consistent with a rimmed depression, the second, with a simple depression with no rim, and the third with a low albedo spot. 3. The regolith particles are backscattering and carbon black is one of the few candidate regolith materials that might explain this low albedo. We conclude that Borrelly's surface is geologically complex to the limit of resolution of the images with a combination complex topography, pits, troughs, peaks and ridges, and some very dark albedo markings, perhaps a factor of two to three darker than the average 3-4% albedo of the surrounding terrains. Our technique utilizing measured radiance profiles through the dark regions is able to discriminate between rimmed depressions, rimless depressions and simple albedo changes not associated with topography.  相似文献   

基于数学形态学的第四系地层遥感影像分割     

梁俊  薛重生  张旺生  陈于  张利华 《测绘科学》2007,32(5):152-153,113

利用数学形态学的方法对遥感影像的第四系地层进行了影像分割实验。经实验结果得出,利用数学形态学的基本运算组合成的各种算子:高、低帽变换、滤波与阈值截取相结合的增强方法,通过选择合适的结构元素,对图像进行预处理后,就可以用形态学方法对第四系地层进行影像分割。经过处理的遥感影像,能够更有效地提取影像的目标。实验结果表明了本文所提的方法的有效性。最后,对形态学方法的不足之处和将来的研究方向展开了讨论。  相似文献   

Experimental investigation of hydrate formation in water-dominated pipeline and its influential factors     

Li Huang  Jia-le Kang  Xiao-dong Shen  Jian-ye Sun  Qing-guo Meng  Qiang Chen  Gao-wei Hu  Chang-ling Liu  Neng-you Wu 《China Geology》2022,5(2):310-321

Blockage in water-dominated flow pipelines due to hydrate reformation has been suggested as a potential safety issue during the hydrate production. In this work, flow velocity-dependent hydrate formation features are investigated in a fluid circulation system with a total length of 39 m. A 9-m section pipe is transparent consisted of two complete rectangular loops. By means of pressurization with gas-saturated water, the system can gradually reach the equilibrium conditions. The result shows that the hydrates are delayed to appear as floccules or thin films covering the methane bubbles. When the circulation velocity is below 750 rpm, hydrate is finally deposited as a “hydrate bed” at upmost of inner wall, narrowing the flow channel of the pipeline. Nevertheless, no plugging is observed during all the experimental runs. The five stages of hydrate deposition are proposed based on the experimental results. It is also revealed that a higher driving pressure is needed at a lower flow rate. The driving force of hydrate formation from gas and water obtained by melting hydrate is higher than that from fresh water with no previous hydrate history. The authors hope that this work will be beneficial for the flow assurance of the following oceanic field hydrate recovery trials.©2022 China Geology Editorial Office.  相似文献   

北京、郑州和深圳三城市空气中气溶胶单颗粒特征的扫描电镜分析   总被引：1，自引：0，他引：1  

赵承美  邵龙义  侯聪  幸娇萍  胡颖  王文华 《岩石矿物学杂志》2015,34(6):925-931

分别采集北京、深圳和郑州3个城市气溶胶样品,使用场发射扫锚电镜-能谱仪观察气溶胶单颗粒的显微形貌和元素组成,并利用图像分析系统对PM2.5的粒径进行了分析。结果表明,城市气溶胶单颗粒类型以矿物颗粒、烟尘和球形颗粒(飞灰和二次粒子)为主。对比3个城市气溶胶中不同颗粒类型数量百分比发现,矿物颗粒数量最多的城市是北京,飞灰和烟尘数量最多的城市是郑州,而规则矿物颗粒数量最多的城市是深圳。3个城市气溶胶单颗粒的数量-粒径分布均呈单峰分布。深圳气溶胶中颗粒物的粒径相对较小,其次为郑州、北京。3个城市气溶胶中颗粒物来源不同程度上都受到交通污染源影响,而燃煤源对北京和郑州气溶胶中颗粒物来源影响仍然不容忽视。  相似文献   

河北中南部平原土壤重金属元素存在形态及生物有效性分析   总被引：9，自引：3，他引：6       下载免费PDF全文

崔邢涛  王学求  栾文楼 《中国地质》2015,(2):655-663

本文以河北省中南部平原农田表层土壤为研究对象,对表层土壤中7种重金属元素的形态含量进行了统计和分析,对重金属元素的生物有效性进行了评价,并运用相关分析法,对影响重金属元素生物有效性的因素进行了研究。结果表明,研究区表层土壤7种重金属元素的有效态含量以Cd最高,达36.83%,潜在生态危害性较大;其次为Pb,达13.37%,其中碳酸盐结合态达到12.38%,由于土壤呈中性或偏碱性,Pb元素的迁移能力较弱,其潜在危害性较小;Cu、Hg、Cr、As、Zn重金属元素含量均以稳定态的含量存在,之和均在90%以上,表明其潜在危害性较小;研究区土壤重金属元素的活性系数和迁移系数大小顺序为:CdPbHgCuZnAsCr和CdHgAsCuPbZnCr,其中Cd的活性系数和迁移系数平均值分别达到0.330和0.160,展现出较强的生物活性、不稳定性和迁移能力,其他重金属元素在土壤中活性系数(Pb除外)和迁移系数均较小,生物活性较弱,在土壤中稳定存在,由土壤中向植物中的迁移能力弱;研究区不同的重金属的生物有效性与其影响因素的关系不尽相同,其主要因素是土壤重金属元素全量,其次为p H、TOC、CEC、粘粒含量等,二者关系复杂。  相似文献   

Strenulagus (Mammalia: Lagomorpha) from the Middle Eocene Irdin Manha Formation of the Erlian Basin, Nei Mongol, China     

?ucja FOSTOWICZ-FRELIK  LI Chuankui  LI Qian  MENG Jin  WANG Yuanqing 《《地质学报》英文版》2015,89(1):12-26

New material of Strenulagus solaris, a stem lagomorph, from the lower part of the Middle Eocene Irdin Manha Formation at the Irdin Manha and Huheboerhe localities, Erlian Basin, Nei Mongol, China includes remains of isolated cheek teeth, fragmentary upper incisors(d I2) and postcranial elements, reported from the species for the first time. The tarsal bones display advanced features, such as a wide calcaneofibular articulation surface and, along with an increase in hypsodonty, the new data document the early stage of lagomorph evolution in the Middle Eocene of the Erlian Basin. This finding is stratigraphically well constrained and probably predates that of the type material of S. solaris from the Khaychin Formation, Bugin-Tsav Basin, Mongolia.  相似文献   

融合光谱-空间信息的高光谱遥感影像增量分类算法   总被引：1，自引：1，他引：0  

王俊淑  江南  张国明  李杨  吕恒 《测绘学报》2015,44(9):1003-1013

提出了一种融合光谱和空间结构信息的高光谱遥感影像增量分类算法INC_SPEC_MPext。通过主成分分析(PCA)提取高光谱影像的若干主成分,利用数学形态学提取各主分量影像对应的形态学剖面(MP),再将所有主分量影像的形态学剖面归并联结,组成扩展的形态学剖面(MPext)。将MPext与光谱信息相结合以增加知识,最大限度地挖掘未标记样本的有用信息,优化分类器的学习能力。不断从分类器对未标记样本的预测结果中甄选置信度高的样本加入训练集,并迭代地利用扩大的训练集进行分类器构建和样本预测。以不同地表覆盖类型的AVIRIS Indian Pines和Hyperion EO-1Botswana作为测试数据,分别与基于光谱、MPext、光谱和MPext融合的分类方法进行比对。试验结果表明,在训练样本数量有限情况下,INC_SPEC_MPext算法在降低分类成本的同时,分类精度和Kappa系数都有不同程度的提高。  相似文献   

地理国情水系要素的自动提取     

张瑞  王圣尧  刘善磊  石善球  周佳 《测绘与空间地理信息》2015,(6):59-61

在地表覆盖水系图斑采集的基础上,利用Rosenfeld细化算法实现地理国情水系要素中心线的自动提取。首先兼顾提取质量确定图像由矢量转换为栅格的最佳像素值,然后根据内存访问效率和图像块大小的关系选择图像分块处理技术。此外,采用图像形态学的膨胀与腐蚀算法、线段长度条件约束和曲线节点抽稀等技术确保中心线提取质量。试验结果表明,本文提出的方法准确、高效,在生产实践中具有一定的应用价值。  相似文献   

结合Gabor纹理与几何特征的高分辨率遥感影像城区道路提取方法     

胡华龙  吴冰  黄邵美 《测绘科学技术学报》2015,(4):395-400

在充分考虑道路频谱在不同频带、不同方向上能量分布的基础上,提出一种基于Gabor纹理与几何特征相结合的高分辨率遥感影像城区道路提取方法。首先通过Gabor滤波器组得到遥感影像不同频带、不同方向上的Gabor纹理特征,并利用K-means方法对遥感影像进行分割;然后利用形态学方法分割与道路相连的地物,并选取适当的几何特征剔除非道路地物;最后利用形态学方法对道路网进行修整。实验结果表明,该方法可以有效、便捷地从高分辨率遥感影像中提取城区主干道路网。  相似文献