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811.
我国渔港沉积物的重金属污染及潜在生态风险评价   总被引:6,自引:1,他引:5  
分析了青岛、宁波、舟山、厦门、深圳、珠海、澳门、茂名和三亚共9个渔港(包括综合港口区)表层沉积物中的Cd、Cu、Pb、Zn、Co和Ni等典型重金属元素的含量,探讨了其可能的来源。采用沉积物质量基准法和Hakanson潜在生态风险指数法,评价了各渔港重金属的污染状况和潜在生态风险。结果表明:(1)渔港沉积物中重金属Cu、Zn、Pb和Cd的富集较为严重,位于珠江三角洲的渔港重金属含量显著高于其他渔港,尤其是Cu和Zn,最高含量分别达到1249mg/kg和664mg/kg,而Cd和Pb的污染也不容忽视;(2)珠三角渔港具“高”或“中等”潜在重金属生态风险,其中Cu和Cd具有高的潜在生态风险,其他渔港均属低生态风险,渔港总的潜在生态风险由高至低顺序为:澳门〉深圳〉珠海〉茂名〉三亚〉厦门〉青岛〉宁波〉舟山;(3)渔港沉积物中重金属主要来自工业废水、生活污水、污灌土壤以及大气沉降的污染和渔船防护漆的使用。而船体防护漆中Cu/氧化亚铜的大量使用是渔港中Cu污染的主要来源。  相似文献   
812.
In the Yangbajing area, southern Tibet, several monogenic volcanoes were conformably superimposed on the Linzizong calc-alkaline volcanic successions. According to their petrologic and geochemical characteristics, these monogenic volcanoes are composed of three rock varieties: tephritic phonolitic plugs and shoshonitic and trachytic lavas. Their geochemical systematics reveals that low-pressure evolutionary processes in the large voluminous Linzizong calc-alkaline magmas were not responsible for the generation of these potassic–ultrapotassic rocks, but the significant change in petrologic and geochemical characteristics from the Linzizong calc-alkaline to potassic–ultrapotassic magma is likely accounted for the change of metasomatic agents in the southern Tibetan lithospheric mantle source during the Paleocene to Eocene. The tephritic phonolites containing both leucite and plagioclase show primary ultrapotassic character similar to that of Mediterranean plagioleucititic magmas. Radiogenic Sr increases with SiO2 in the xenolith-bearing trachytes strongly suggesting significant crustal assimilation in the shoshonitic magmas. The Yangbajing ultrapotassic rocks have high K2O and Al2O3, and show depletion of high field strength elements (HFSEs) with respect to large ion lithophile elements. In primitive mantle-normalized element diagrams, all samples are characterized by positive spikes at Th (U) and Pb with negative anomalies at Ba, Nb–Ta and Ti, reflecting the orogenic nature of the ultrapotassic rocks. They are characterized by highly radiogenic 87Sr/86Sr(i) ratios (0.7061–0.7063) and unradiogenic 143Nd/144Nd(i) (0.5125), and Pb isotopic compositions (206Pb/204Pb = 18.688–18.733, 207Pb/204Pb = 15.613–15.637, and 208Pb/204Pb = 38.861–38.930) similar to the global subducting sediment. Strong enrichment of incompatible trace elements and high Th fractionation from the other HFSEs (such as Nb and U) clearly indicate that the Th-enriched sedimentary component in a network veined mantle source was mainly introduced by sediment-derived melts. In addition, the ultrapotassic rocks have significant Ce (Ce/Ce* = 0.77–0.84) and Eu (Eu/Eu* = 0.72–0.75) anomalies, suggesting a subduction sediment input into the southern Tibetan lithospheric mantle source. In contrast, high U/Th (> 0.20) and Ba/Th (> 32) and low Th/La (< 0.3) in the shoshonites indicate that the Eocene potassic magma originated from partial melting of the surrounding peridotite mantle pervasively affected by slab-related fluid addition from the dehydration of either the subducting oceanic crust or the sediment. Thus, at least two different subduction-related metasomatic agents re-fertilized the upper mantle. According to the radiometric ages and spatial distribution, the Gangdese magmatic association shows a temporal succession from the Linzizong calc-alkaline to ultrapotassic magmas. This indicates a late arrival of recycled sediments within the Tibetan lithospheric mantle wedge. The most diagnostic signatures for the involvement of continent-derived materials are the super-chondritic Zr/Hf (45.5–49.2) and elevated Hf/Sm values (0.81–0.91) in the ultrapotassic rocks. Therefore, the occurrence of orogenic magmatism in the Gangdese belt likely represents the volcanic expression of the onset of the India–Asia collision, preceding the 10 Ma Neo-Tethyan slab break-off process at 42–40 Ma. The absence of residual garnet in the mantle source for the ultrapotassic volcanism seems to imply that the southern Tibetan lithosphere was not been remarkably thickened until the Eocene (~ 50 Ma).  相似文献   
813.
814.
李伍铜矿床控矿构造地质特征及演化模式探讨   总被引:11,自引:1,他引:11  
四川李伍铜矿床是我国西南地区一个中型富铜矿床,其矿床历经了多期次的构造演化和叠加。江浪穹隆体的变形变质对早期的矿源层具改造、矿液初步富集作用;构造岩性层控制了李伍铜矿床的产出与分布,S3期沿S2面理发育起来的大型平卧褶皱控制了矿体的空间形态,成穹阶段形成的滑脱剪切带是矿液运移的通道,也是找矿的有利场所,该带中次级逆冲断面及EW向挤压时期形成的S3面理挠曲是容矿空间,变形与成穹作用双重机制对该矿床构造的形成至关重要。  相似文献   
815.
侯龙君  祝田多娃  李法军 《地下水》2010,32(6):12-12,20
阐述了水文地质参数的重要性,及其发展和尚需完善的方面。推出可以解决基岩裂隙、溶隙含水层坐标距离与水力距离不一致问题的导水系数计算方法。该方法的特点是简捷,能较直观地判别含水层主要水文地质参数的大小,具有很高的可靠性。  相似文献   
816.
将有限元强度折减理论应用于边坡稳定性分析中,运用ANSYS大型有限元分析软件,基于Drucker-Prager(D-P)屈服准则,采用力和位移的收敛标准作为破坏判据,进行边坡的稳定性分析。当折减系数达到某一数值时,非线性有限元静力计算将不收敛,滑面上的位移将产生突变,边坡内一定幅值的广义剪应变自坡底向坡顶贯通,此时认为边坡已破坏,并定义此时的折减系数即为稳定系数。文中以韩城煤矿节理岩质边坡为例,运用该方法进行了稳定性分析并与并与传统的Bishop法、Janbu法等方法对比。计算结果表明,有限元强度折减法能更加真实地反映边坡的实际情况,求得的边坡稳定系数更接近边坡的实际稳定状态,显示出其在边坡稳定性分析中的一定优势。  相似文献   
817.
寒武系下统牛蹄塘组黑色岩系广泛分布于鄂西地区,层内现已发现众多的钼钒矿床(点),其形成条件具有热水沉积与正常海相沉积双重特征,成矿系统总体上处在海侵体系域陆棚盆地还原沉积环境,期间由区域性断裂构造的热水喷流提供多种金属元素来源,经炭质、粘土矿物吸附作用沉积成矿,其中Ni、Mo与喷流作用最为密切,钒与生物化学作用密切,具有较好的找矿远景。  相似文献   
818.
渤海湾西岸细砂质潮间带的成因分析   总被引:1,自引:1,他引:0  
根据在海河口南缘至独流减河岸段潮间带地区采集的36个表层和1个无扰动柱状沉积物样品的粒度分析结果,探讨了该岸段的粒度分布特征.结果表明:平面上(自南向北),该潮间带表层沉积物由粉砂质砂变为细砂,呈逐渐变粗、分选性变好的趋势;垂向上,潮间带表层45 cm以下主要为粉砂质砂和粘土质粉砂的互层沉积,向上,渐变为细砂或极细砂,显示向上变粗、分选性变好的趋势.这一向北、向上变粗、分选变好的总趋势,是近半个世纪以来因海河防潮闸的修建而使河流泥砂输运能力降低、近岸海洋影响增强的海河三角洲退化的现代过程的反映.  相似文献   
819.
Hybrid anaerobic baffled reactor for treatment of desizing wastewater   总被引:3,自引:3,他引:0  
Polyvinyl alcohol-containing desizing wastewater discharged within final textile wastewater has a great impact to the environment due to its poor biodegradability. An improved lab-scale hybrid anaerobic baffled reactor was developed to treat desizing wastewater. The modification was achieved by increasing the height of hybrid anaerobic baffled reactor and application of proper effluent recycle enabled to increase the ability of entrapping microbe-rich small particles in the reactor and prompted the formation of granules. The significant difficulty in hybrid anaerobic baffled reactor operation is the slow start-up procedure, which is crucial to the overall polyvinyl alcohol-containing desizing wastewater treatment. Therefore, the ability of a hybrid anaerobic baffled reactor, treating desizing wastewater, to achieve a prompt start-up was studied at lab-scale. Results showed that inoculated with anaerobic granular sludge and adoption of effluent recycle during start-up, the system demonstrated a good performance of polyvinyl alcohol removal efficiency (above 17.2 %) and satisfactory stability of pH and alkalinity in effluent (range around 7.4–8.0 and 700–920 mg/L, respectively) and the sludge appeared obviously granulation. Thus, the prompt start-up was achieved after 60 days. The start-up strategy used for this process has achieved its goals by creating an active microbial population. The improved lab-scale hybrid anaerobic baffled reactor proved to be an efficient reactor configuration for the treatment of desizing wastewater, which favored the prompt start-up of hybrid anaerobic baffled reactor. The results also provide evidence to modify the design of anaerobic baffled reactor to improve reactor performance.  相似文献   
820.
煤矿巷道围岩稳定性动态工程分类技术研究与应用   总被引:4,自引:0,他引:4  
基于围岩质量计算,柱状图数字化与重组,围岩结构诊断,采动应力作用后围岩结构演化等研究成果,采用“工程要求,基本结构,演化结构、为一级指标,提出了巷道围岩稳定性动态工程分类技术,分类结构的表在技术及分类结果的应用方法。  相似文献   
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