排序方式: 共有38条查询结果,搜索用时 15 毫秒
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区域地下水水质是水质评价的重要内容,也是合理制定地下水开发利用及保护治理方案的基本前提。以科尔沁沙地奈曼地区地下水水质为研究对象,选取2005-2014年地下水水质监测数据,分析地下水水质时空变化特征。结果表明:近10年来奈曼地区地下水水质各指标均值均低于地下水Ⅱ类标准,pH值、NO3-含量、化学需氧量(CODcr)在局部地区出现超标现象,但水质总体较好;该地区地下水矿化度(TDS)与Ca2+、Mg2+、Na+、HCO3-、SO42+浓度及CODcr具有明显的正相关关系,即随着Ca2+、Mg2+、Na+、HCO3-、SO42+、CODcr浓度的增加,TDS也会增加;各主要指标浓度随时间呈下降趋势,SO42+、Na+、HCO3-浓度及TDS较稳定,而Ca2+、Mg2+、Cl-、PO43-浓度及CODcr随时间变化较为明显;Ca2+、Mg2+ 、HCO3-、SO42+浓度及TDS农田非灌溉井> 农田灌溉井> 沙地水位井,Na+、CODcr浓度沙地水位井> 农田非灌溉井> 农田灌溉井,NO3-浓度沙地水位井> 农田灌溉井> 农田非灌溉井;该地区地下水水质变化主要与碳酸盐岩溶解、农药化肥的使用、工业及生活污水排放有关。 相似文献
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Paleozoic Epithermal Au and Porphyry Cu Deposits in North Xinjiang, China: Epochs, Features, Tectonic Linkage and Exploration Significance 总被引:31,自引:1,他引:31
Kezhang Qin Shu Sun Jiliang Li Tonghui Fang Shulai Wang Wei Liu 《Resource Geology》2002,52(4):291-300
Abstract. Based on field investigation of large number of ore deposits including some latest discoveries and multidiscipline comprehensive research, we demonstrated the general features of metallic deposits and we suggest that Paleozoic archipelago-type collisional orogen at North Xinjiang, northwestern China show intimate similarity with the metallogenesis of Southeast Asia Cenozoic archipelago. We briefly described the characteristics of major porphyry-type, skarn-type Cu deposits and typical high-sulfidation type (HS-type) and low-sulfidation type (LS-type) epithermal Au deposits as well as some latest discoveries. Systematic isotopic age-dating on the Tuwu-Yandong superlarge porphyry Cu deposits revealed that they formed in Late Devonian to Early Carboniferous in an accretionary arc setting. The tectonic settings of epithermal Au deposits and its linkage with porphyry Cu deposits are further discussed. The formation condition for porphyry Cu deposits is more strict than epithermal Au deposits. The distribution width for porphyry Cu deposits in the orogenic belts is more limited than epithermal Au deposits. The discovery and prospecting progress of the Kalatage HS-type Cu-Au deposit were reported. The significance in further exploration was suggested. 相似文献
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WANG Zhaolin YAN Jiayong ZHENG Xiaoming TANG Hejun YUAN Lulu DENG Zhen FANG Tonghui 《《地质学报》英文版》2023,97(3):727-743
The Hongshishan chromitite deposits are situated to the north of the Beishan orogenic collage, in the southern part of the Central Asian Orogenic Belt. This study describes the mineral chemistry, Re-Os isotopes and platinum-group elements geochemistry of the Hongshishan chromitites for the purpose of constraining the origin, evolution and composition of their parental melts. The restricted ranges of Al2O3, Cr2O3 and Cr#-Mg# variation of chromite-cores ... 相似文献
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渤海湾盆地东营凹陷沙河街组页岩油储层微观孔隙特征 总被引:3,自引:0,他引:3
通过场发射环境扫描电镜、低温氮气吸脱附实验、高分辨率背散射电子图像定量分析等技术方法,对渤海湾盆地东营凹陷沙河街组页岩油储层的微观孔隙类型、结构特征及孔隙分布进行了系统研究。结果表明:沙河街组页岩油储层微观孔隙类型多样,包括粒间孔、粒内孔、晶间孔、溶蚀孔和晶内孔5类孔隙。有利储集空间为孔径在100~3000nm的孔隙,以粒间孔、粒内孔和溶蚀孔为主。泥岩类和灰岩类孔隙形态包括细颈瓶状(墨水瓶状)和平行板状;白云岩类孔隙形态为平行板状,连通性最好。白云岩类定量面孔率最大且孔隙发育最好,其次为泥岩类,灰岩类较差。影响微观孔隙特征的主要因素包括矿物成分及含量、有机质生排烃和热液作用,其中黏土矿物和泥级颗粒有利于储层微孔发育,方解石的胶结作用和重结晶作用不利于孔隙发育。生排烃产生的有机酸和热液作用增进了次生孔隙的形成。 相似文献
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Effects of grazing and livestock exclusion on soil physical and chemical properties in desertified sandy grassland,Inner Mongolia,northern China 总被引:3,自引:1,他引:2
Yuqiang Li Halin Zhao Xueyong Zhao Tonghui Zhang Yulin Li Jianyuan Cui 《Environmental Earth Sciences》2011,63(4):771-783
Heavy grazing is recognized as one of the main causes of vegetation and soil degradation and desertification in the semiarid
Horqin sandy grassland of northern China. Soil physical and chemical properties were examined under continuous grazing and
exclusion of livestock for 8 years in a representative desertified sandy grassland. Exclosure increased the mean soil organic
C, total N, fine sand and silt + clay contents, inorganic C (CaCO3), electrical conductivity, and mineral contents (including Al2O3, K2O, Na2O, Fe2O3, CaO, MgO, TiO2, MnO), microelements (Fe, Mn, Zn, B, Cu, Mo), and heavy metals (Pb, Cr, Ni, As, Hg, Cd, Se), and decreased the coarse sand
content, bulk density, and SiO2 in the top 100 cm of the soil. Livestock exclusion also improved available N, P, K, Fe, Mn, and Cu, exchangeable K+, and the cation exchange capacity, but decreased pH, exchangeable Na+, and available S, Zn, and Mo in the top 20 cm of the soil. The greatest change in soil properties was observed in the topsoil.
The results confirm that the desertified grassland is recovering after removal of the livestock disturbance, but that recovery
is a slow process. 相似文献
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试验了温室葡萄超氧化物气化酶(SOD)活性、过氧化氢酶(CAT)活性、游离脯氨酸(Pro)含量、丙二醛(MDA)含量和果粒生长对地表覆盖的响应。结果表明:整个生育期内,砂土覆盖、秸秆覆盖、秸秆+白地膜覆盖及秸秆+黑地膜覆盖都对0~40 cm土层土壤有显著的保水作用,其中秸秆+黑地膜保水性能最强(土壤含水量比无覆盖的提高14.53%,P<0.05),且各覆盖方式的保水能力随着土层的加深而增强。秸秆+白地膜覆盖下葡萄细胞的抗氧化酶活性最高。砂土覆盖极显著(P<0.01)提高果粒内Pro含量(约增加42.40%)。砂土覆盖后葡萄果粒粒径最大,秸秆+地膜覆盖、秸秆覆盖下的果粒粒径均小于无覆盖的粒径。秸秆覆盖能够提高土壤水分含量,抑制果粒的增长。砂土覆盖可以作为温室葡萄适宜覆盖方式。 相似文献
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为了分析珠江口区域海岸线近年来的发展变化情况,文章基于分形理论,分别对珠江口及深圳段大陆海岸线2005-2019年的变迁趋势采用网格法进行分形分析,得出14年间,珠江口及深圳段海岸线分维数的变化情况。通过对计算结果的分析对比发现,近年间珠江口海岸线整体因开发强度大,人工岸线居多,分维数值变化较小;而深圳段海岸线分维数较整个珠江口有较大幅度增加。深圳段海岸线曲折度提高的原因主要为修复类工程的实施。海岸线分形维数与海岸线曲折程度的正相关系,与海岸带开发利用规划管理要求相符,提出分维数可作为规划用海的重要评估参数。 相似文献
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