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871.
Discovery of Cinnabar in Soils in Hg Anomalous Zones in City and Town Areas and Their Surroundings and Its Significance 总被引:1,自引:1,他引:0
ZHU Lixin MA Shengming WANG Zhifeng China University of Geosciences Beijing Institute of Geophysical Geochemical Exploration Chinese Academy of Geological Sciences Langfang Hebei 《《地质学报》英文版》2005,79(2):286-290
As a result of systematic study on heavy minerals in soils at city and town areas and their surroundings,cinnabar was discovered for the first time in areas of Hg anomalies in China, and it was found that the distribution of cinnabar was basically coincident in scope with that of Hg anomalies, showing that Hg anomalies were‘closely related to cinnabar. This finding provides a theoretical basis for a verification of Hg anomalies in soils in city and town areas and their surroundings, as well as evaluation of its ecological effects, and is significant to revealing the occurrence modes and origin of Hg in soils. 相似文献
872.
运用小波变换与支持向量机耦合模型(WA-SVM)预测干旱区地下水埋深 总被引:2,自引:2,他引:0
准确预测干旱区地下水埋深,对区域地下水资源的合理开发利用与生态环境保护具有十分重要的意义。以额济纳盆地3个地下水埋深观测井为对象,运用小波变换与支持向量机耦合模型(WA-SVM)对观测井未来1个月的地下水埋深进行了短期预测。为检验WA-SVM的有效性,将模拟结果与未经小波变换的SVM模型进行了对比。结果表明:在对干旱区地下水埋深进行短期预测时,相较于SVM模型,WA-SVM模型的预测精度显著提高。WA-SVM模型在干旱区地下水埋深预测中有更好的适用性,可以为干旱地区地下水埋深动态预测提供新的方法和思路,是资料有限的条件下地下水埋深预测的有效方法。 相似文献
873.
针对中国西北干旱区普遍存在的土壤盐渍化,以渭干河-库车河绿洲TM影像数据,建立BP神经网络结合Adaboost算法的土壤盐渍化预警度评价模型。首先,根据研究区实际情况设置该模型的4个预警指标(地下水埋深、海拔、盐分指数、归一化干旱指数),分别提取其连续表面信息,结合BP神经网络作为弱预测器进行预测,将通过不同训练集得到的弱预测器结果结合成强预测器。在利用该模型训练样本时,依据各评价因子对分类结果的贡献率调整其权重,预测的结果能客观反映每个评价因子对该地区土壤盐渍化的贡献程度。结果表明,研究区警情总体情况较严重,绿洲北部内部耕地周围的荒地以及含水量少的区域,盐渍化危险度较高。 相似文献
874.
Jun Niu Bellie Sivakumar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(4):857-865
The East River in South China plays a key role in the socio-economic development in the region and surrounding areas. Adequate understanding of the hydrologic response to land use change is crucial to develop sustainable water resources management strategies in the region. The present study makes an attempt to evaluate the possible impacts of land use change on hydrologic response using a numerical model and corresponding available vegetation datasets. The variable infiltration capacity model is applied to simulate runoff responses to several land use scenarios within the basin (e.g., afforestation, deforestation, and reduction in farmland area) for the period 1952–2000. The results indicate that annual runoff is reduced by 3.5 % (32.3 mm) when 25 % of the current grassland area (including grasslands and wooded grasslands, with 46.8 % of total vegetation cover) is converted to forestland. Afforestation results in reduction in the monthly flow volume, peak flow, and low flow, but with significantly greater reduction in low flow for the basin. The simulated annual runoff increases by about 1.4 % (12.6 mm) in the deforestation scenario by changing forestland (including deciduous broadleaf, evergreen needleleaf, and broadleaf, with 15.6 % of total vegetation cover) to grassland area. Increase in seasonal runoff occurs mainly in autumn for converting cropland to bare soil. 相似文献
875.
ZHANG ChenChen ZHANG Shun WEI Wei WU ChaoDong LIANG JiangPing NIU Wen DU JinXia FU XiuLi CUI KunNing WANG Chao WANG Hui 《中国科学:地球科学(英文版)》2014,57(2):278-296
The Nenjiang Formation in the Songliao Basin is a symmetrical sequence of progradation-retrogradation,and is formed in the transgression cycle and regression cycle(T-R cycles)of the base level of deposition.We analyzed the drilling,well logging,core data,and seismic profiles of basin level,and by using the sequence stratigraphy,identified one secondary sequence boundary,two third-order sequence boundaries,and eight fourth-order sequence boundaries in the Nenjiang Formation.These eleven sequence boundaries can be divided into structural unconformity,depositional unconformity,flooding surface,and forced regression surface.Therefore the Nenjiang Formation can be subdivided into one secondary sequence,three third-order sequences,and ten fourth-order sequences.We have restored the sedimentary filling evolution within the stratigraphic framework of fourth-order sequences in the Nenjiang Formation.The sedimentary period of the first member of the Nenjiang Formation was corresponded to the global transgression period,which is also the development period of transgression cycle(T cycle),when the lake basin had the largest scope and deepest sedimentary water,the SB07(the maximum flooding surface)was formed on the top of strata during this period;covering above the SB07,there developed a set of condensation layer-oil shale,which is distributed in the whole basin and is the important source bed and regional cover.Therefore,a retrogradation sequence was formed in the T cycle of the first member of the Nenjiang Formation,characterized by the retrograding delta at a low angle.The delta has a giant front,a small plain,and many underwater distributary channels.Meanwhile,large gravity flow channels and sublacustrine fans are developed in the front of the delta.During the depositional period of the second member of the Nenjiang Formation,the R cycle began to develop due to the compression of the pacific tectonic domain;the source direction rotated 90°along with the eastern uplifting of the basin,and formed a series of east-west prograded and forced retrogradations.The prograding delta at high angel was developed in the interior of the sequence;the delta had a small front,a giant plain,and fewer underwater distributary channels,with the collapse at the foreslope,forming a series of slump fans.The slump fans can be divided into three types:discrete type,superimposed type,and fluid type.We built a whole"triad model"of the slump fan.Pointed out that the sequence of forced retrogradation formed by R cycle is a good structural mark of basin optimization,and rejected the viewpoint of"transgression"in the Nenjiang Formation of the Songliao Basin. 相似文献
876.
江汉盆地为中国东部典型的中、新生代盐湖盆地,近些年在新沟油田古近系新沟嘴组发现致密油藏,储集层主要为与盐韵律相关的白云岩和粉砂岩层。为了探究盐韵律的发育特征及其意义,作者以岩心精细观察为基础,结合测录井、分析化验资料,根据盐矿物种类、剖面结构和厚度,对新沟嘴组盐韵律发育规模进行了不同级别的划分,对各级韵律的剖面特征进行了描述,并对其形成机理进行了分析。在此基础上,从古气候及油气2个角度探讨了盐韵律的地质意义。盐韵律的形成是湖平面上升-下降不断变化的直接响应。新沟嘴组盐韵律中广泛发育广温相盐类矿物白云石、方解石,指示江汉盆地古近系新沟嘴期的气候特征为古温度介于寒冷和炎热之间的过渡型半干旱-干旱气候;一个完整的盐韵律可以形成一个生储盖组合,对油气生成、储集和保存具有重要意义。 相似文献
877.
古地貌对渤海石臼坨凸起古近系沉积体系的控制作用 总被引:1,自引:0,他引:1
渤海湾盆地石臼坨凸起沙一、二段所发育的扇三角洲储层,在沉积演化过程中由于古地貌特征的不同,造成储集砂体形态特征及分布规律的不同,储层认识困难。通过分析断裂活动对古地貌格局的控制作用进行古地貌恢复,研究不同地貌单元与沉积体系的匹配关系,阐明了古地貌对沉积体系发育类型和沉积特征的控制作用,揭示了扇三角洲的沉积过程。在此基础上结合地震属性分析技术,精细描述了各沉积期次扇体的展布特征,并对沉积演化过程中扇三角洲沉积体系发育的差异性进行了解析。最终明确了盆地边缘沟谷和古地形发育特征对物源的控制作用,形成了"大沟对大扇,小沟对小扇"的沉积模式指导依据;同时确定了斜坡带上扇三角洲的沉积规律和砂体分布的控制机理。 相似文献
878.
为提高好氧污泥颗粒化速度, 采用微生物絮凝剂, 探讨在好氧颗粒污泥培养过程中微生物絮凝剂的投加方式对颗粒污泥理化性能及生物降解效能的影响。结果表明:微生物絮凝剂每隔2、3、5、7 d投加一次时, 均可培养出成熟的好氧颗粒污泥, 微生物絮凝剂的投加方式对好氧污泥颗粒化的影响较显著;微生物絮凝剂最佳投加方式为每5天投加一次, 此时颗粒化速度快, 颗粒形成时间由未投加的60 d缩短为42 d, 好氧颗粒污泥疏水性好, 污泥体积指数稳定在40 mL/g左右, 沉降速度达35.06 m/h, COD、氨氮和总磷的去除率分别为96.55%、93.29%和87.29%。 相似文献
879.
880.
关于气象与人体健康研究的几个问题 总被引:2,自引:0,他引:2
关于气象、环境与健康问题的研究可总结为如下几个问题:1)气候变化及其影响,2)天气、气候变化与人类健康,3)大气污染与人类健康,4)关于气象条件与疾病的机理研究,5)环境与健康危险度评价。作者认为以下几个问题值得我国学者予以关注:1)气象与健康问题的检测,2)气侯变化与人类健康,3)气象与人类健康关系的机理研究,4)应用数值模式研究气象与健康问题,5)环境与健康危险度评价,6)疾病预测和预警研究,7)多学科交叉研究和更多部门对气象与健康问题的介入。 相似文献