Total mercury in terrestrial systems (air-soil-plant-water) at the mining region of San Joaquín,Queretaro, Mexico     

Sergio Martínez-Trinidad  Gilberto Hernández Silva  Juventino Martínez Reyes  Gregorio Solorio Munguía  Sara Solís Valdez  Martha Elena Ramírez Islas  Rocío García Martínez 《Geofísica Internacional》2013,52(1):43-58

Deficient management of cinnabar mining left the San Joaquín region with high concentrations of mercury in its soils (2.4 – 4164 mg kg^-1). Numerous cinnabar mines have contributed to the dispersion of mercury into agricultural (0.5 –314 mg kg^-1) and forest (0.2 – 69 mg kg^-1) soils. Sediments are a natural means of transportation for mercury, causing its spreading, especially in areas near mine entrances (0.6 – 687 mg kg^-1). The nearness of maize crops to mines favors mercury accumulation in the different plant structures, such as roots, stems, leaves, and grain (0.04 – 8.2 mg kg^-1); these being related to mercury volatilization and accumulation in soils. Mercury vapor present in the settlements could indicate a constant volatilization from lands and soils (22 – 153 ng m^-3). The mercury levels found in the soils, in maize grain, and in the air resulted greater than the standards reported by the Official Mexican Norm (NOM) and the World Health Organization (WHO). Mercury in rainwater is due mainly to the presence of suspended atmospheric particles, later deposited on the surface (1.5 – 339 μg |^-1). Mercury dissolution was found in the drinking water (10 – 170 ng |^-1), with concentrations below those established by the NOM and the WHO. The contamination existing in the San Joaquín region does not reach the levels of the world’s greatest mercury producers: Almaden (Spain) and Idrija (Slovenia). It is, however, like that found in other important second degree world producers such as Guizhou (China). The population of San Joaquín, as well as its surrounding environment, are constantly exposed to mercury contamination, thus making a long term monitoring necessary to determine its effects, especially to people.  相似文献   

Large roughness element effects on sand transport,Oceano Dunes,California     

John A. Gillies  Nicholas Lancaster 《地球表面变化过程与地形》2013,38(8):785-792

The effect of large roughness elements on sand transport efficiency was evaluated on a coastal sand sheet by measuring sand flux with two types of sand traps [Big Spring Number Eight (BSNE) and the Cox Sand Catcher (CSC)] at 30 positions through a 100 m‐long × 50 m‐wide roughness array comprised of 210 elements each with the dimensions 1·17 m long × 0·4 m high × 0·6 m wide. The 210 elements were used to create a roughness density (λ) of 0·022 (λ = n bh/S, where n is the number of elements, b the element breadth, h the element height, and S is the area of the surface that contains all the elements) in an area of 5000 m². The mean normalized saltation flux (NSF) values (NSF = outgoing sand flux/incoming sand flux) at the furthest downwind distance for the two trap types were 0·44 and 0·41, respectively. This is in excellent agreement with an empirical model prediction of 0·5. The reduction in saltation flux is similar to an earlier separate study for an equivalent λ composed of elements of similar height (0·36 m), even though the roughness element forms were different (rectangular in this study as opposed to circular) as were the horizontal porosity of the arrays (49% versus 16%). This corroborates earlier results that roughness element height is a critical parameter that enhances reduction in sand transport by wind for similar λ configurations. The available data suggest the form of the relationship between transport reduction efficiency and height is likely a power relationship with two limiting conditions: (1) for elements ≤ 0·1 m high the effect is minimized, and (2) as element height matches and then exceeds the maximum height of the saltation layer (≥ 1 m), the effect will stabilize near a maximum of NSF ≈ 0·32. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

矿区三维地质建模与地裂缝成因分析     

文晔  徐爱功  杨帆 《测绘科学》2013,38(4):43-45

为了分析在复杂地质条件下采煤引起的大规模地表裂缝的形成原因,本文以某矿区地裂缝为研究对象、数字化软件SURPAC为技术平台、岩体为主要区域变量,建立关于开采工作面、火成岩、地裂缝及断层的三维地质模型,并进行开采沉陷影响预计,通过分析裂缝成因中各相关地质条件的作用影响,得出了煤炭开采导致地下应力平衡被打破后造成地裂缝的主要因素,为预防和治理地裂缝提供了参考。  相似文献   

Development of a data mining method for land control     

Wang Shuliang  Wang Xinzhou  Shi Wenzhong 《地球空间信息科学学报》2013,16(1):68-76

Land resources are facing crises of being misused, especially for an intersection area between town and country, and land control has to be enforced. This paper presents a development of data mining method for land control. A vector-match method for the prerequisite of data mining i. e., data cleaning is proposed, which deals with both character and numeric data via vectorizing character-string and matching number. A minimal decision algorithm of rough set is used to discover the knowledge hidden in the data warehouse. In order to monitor land use dynamically and accurately, it is suggested to set up a real-time land control system based on GPS, digital photogrammetry and online data mining. Finally, the means is applied in the intersection area between town and country of Wuhan city, and a set of knowledge about land control is discovered.  相似文献   

Analysis of spatial clustering optimization     

Jianfeng Yang  Puliu Yan  Delin Xia  Qing Geng 《地球空间信息科学学报》2013,16(4):302-307

Spatial clustering is widely used in many fields such as WSN (Wireless Sensor Networks), web clustering, remote sensing and so on for discovery groups and to identify interesting distributions in the underlying database. By discussing the relationships between the optimal clustering and the initial seeds, a clustering validity index and the principle of seeking initial seeds were proposed, and on this principle we recommend an initial seed-seeking strategy: SSPG (Single-Shortest-Path Graph). With SSPG strategy used in clustering algorithms, we find that the result of clustering is optimized with more probability. At the end of the paper, according to the combinational theory of optimization, a method is proposed to obtain optimal reference k value of cluster number, and is proven to be efficient.  相似文献   

Change detection of surface mining activity and reclamation based on a machine learning approach of multi-temporal Landsat TM imagery     

George P. Petropoulos  Panagiotis Partsinevelos  Zinovia Mitraka 《国际地球制图》2013,28(4):323-342

Being able to quantify land cover changes due to mining and reclamation at a watershed scale is of critical importance in managing and assessing their potential impacts to the Earth system. In this study, a remote sensing-based methodology is proposed for quantifying the impact of surface mining activity and reclamation from a watershed to local scale. The method is based on a Support Vector Machines (SVMs) classifier combined with multi-temporal change detection of Landsat TM imagery. The performance of the technique was evaluated at selected open mining sites located in the island of Milos in Greece. Assessment of the mining impact in the studied areas was based on the confusion matrix statistics, supported by co-orbital QuickBird-2 very high spatial resolution imagery. Overall classification accuracy of the thematic land cover maps produced was reported over 90%. Our analysis showed expansion of mining activity throughout the whole 23-year study period, while the transition of mining areas to soil and vegetation was evident in varying rates. Our results evidenced the ability of the method under investigation in deriving highly and accurate land cover change maps, able to identify the mining areas as well as those in which excavation was replaced by natural vegetation. All in all, the proposed technique showed considerable promise towards the support of a sustainable environmental development and prudent resource management.  相似文献   

应用遥感影像制作矿区大比例尺地形图     

林楠  姜琦刚  刘德利 《测绘科学》2013,38(3):178-180

本文在专业的遥感和地理信息系统软件平台支持下,利用Aster立体像对和IKONOS高分辨率遥感影像分别提取矿区地形信息和地物信息,结合矿区的实际特点,参照地形图制作规范对矿区大比例尺地形图的制作进行了分析和探讨,结果表明利用遥感影像进行矿区大比例尺地形图制作不但周期短、速度快、时效性强,而且精度完全能够满足生产需要,是一种实用可行的方法。  相似文献   

鲁豫交界地区深井水位持续大幅度下降原因分析   总被引：4，自引：2，他引：2  

孙小龙  刘耀炜  马玉川  晏锐 《中国地震》2013,29(1):132-141

鲁豫交界地区豫01、11井和鲁27井等3口地震观测深井的水位于2006年后出现了准同步的异常下降变化,下降幅度3 ～12m不等.经调查落实,发现该地区近年来地热开采活动日益增强,开采量逐年增大,并且开采层与异常井水位观测层同属于奥陶系热储层.为此,本文依据聊城-兰考断裂带附近区域的水文地质构造特征,建立了三维地下水流动模型,基于周边地热开采量数据和相关含水层参数,运用有限差分方法计算了地热开采所引起的区域水位降落漏斗,并分析了水位下降异常的时间演化和空间分布特征.结果显示,聊城-兰考断裂带附近区域自1995年开始地热开采活动以来,其逐年增加的地热开采量与地震观测井水位的下降幅度之间存在较好的对应关系,分析认为鲁豫交界地区3口深井水位的准同步异常下降与周边地热开采活动有关.  相似文献   

Petrography of alluvial sands as a past and present environmental indicator: Case of the Loire River (France)     

Jean-Jacques MACAIRE  Isabelle GAY-OVEJERO  Michel BACCHI  Constantin COCIRTA  Luc PATRYL  Stéphane RODRIGUES 《国际泥沙研究》2013,28(3):285-303

Four sample sets of the Upper and Middle Loire river sands were analyzed in order to study the impact of natural and anthropogenic factors on their petrographic composition in space (on an 800 km stretch) and time. Composition was determined by modal analysis of three sand-size fractions using a polarizing optical microscope and calculated for each sample (“standard sand” = Sst). The watershed is composed mainly of endogenic (Massif Central) and sedimentary (southern Parisian Basin) rocks. B-set sands collected in channels for different water flows in 1996 show that Sst compositions vary by only 5 %. Present-day sands in the Upper Loire and Middle Loire have very high petrographic immaturity comparing to others worldwide fluvial sands, although bio-climatic conditions favor sand maturation by source-rock weathering in the watershed. This shows the strong impact of the Massif Central on sediment yield due to relief rejuvenation as a consequence of the formation of the Alps during the Quaternary. Fluvial sands stored during the Weichselian and the Holocene in the Middle Loire floodplain, although partly weathered since their deposition, show higher inputs from the endogenic rocks of the Massif Central than present-day deposits. This can be explained by Weichselian periglacial conditions and the development of crop farming since the Neolithic, which favored mechanical erosion, particularly in the Massif Central which is characterized by a cold, humid climate and steep slopes. The upstream-downstream change in the composition of presently deposited sand is low in the diked area. It shows however that basalt and some heavy mineral grains are vulnerable to abrasion during transport and indicates a marked sediment yield from ancient sediment stored in the floodplain. This is in line with the high incision of the river bed over the last 150 years partly due to dam construction and aggregate mining.  相似文献   

老挝波乔省某磁铁矿区磁法勘探     

陈载林  左琼华  王建飞 《地球物理学进展》2013,28(3)

勘查区位于老挝西北部之波乔省,地表风化严重、浮土掩盖厚、深林茂密、基岩露头少,虽然局部地段出露有大量的铁帽,但不敢判断该区是否有大规模的磁铁矿.为此,我们采用1∶10000地面高精度磁法测量以了解磁铁矿的有无、范围、延伸、规模.后期勘探阶段开展2.5D人机交互正反演工作以了解深部磁铁矿的有无.结果表明,在老挝西北部地质勘查程度低的地区开展高精度磁测扫面工作是寻找磁铁矿产行之有效的方法,能够解决基础地质问题,矿山勘查问题,后期运用2.5D人机交互正反演能够解决一定的矿层预测工作.  相似文献