漓江水系汞的分布和污染研究   总被引：1，自引：0，他引：1  

钱建平  张力  曹超  牛云飞  梁桂莲  江文莹  许明  江沙 《地球化学》2010,39(4):314-325

对漓江水系干流、支流、连体湖泊、较大的孤立湖塘和近岸水井设置40个采样点。水样采样周期为2个水文年,分枯水季和丰水季两次采样,现场测定水温、电导率、pH值等理化参数。系统采集水样112件、底泥样40件、水草样40件、近岸土壤样40件。底泥样用逐步浸提法进行不同形态汞分析。研究结果显示,干流河水、底泥和水草中汞的平均含量分别为0．12μg／L、0．20μg／g和0．032μg／g;主要支流河水、底泥和水草中汞的平均含量高于干流,分别为0．15—0．23μg／L、0．38～1．7μg／g和0．028—0．044μg／g。底泥中汞含量均高于近岸土壤汞含量。无论是干流还是支流,河水汞含量与底泥、水草汞含量有明显的相关关系。由上游至下游,漓江水系干流、主要支流河水样汞含量均不断增高,可高出源头河水汞含量的1．5—5倍。相应地指示重金属离子污染的参考指标——电导率值不断增高,河水的pH值亦逐渐增高。丰水期（5月至6月）河水中的汞含量（0．12—0．28μg／L）明显高于枯水期（9月至11月）河水中的汞含量（0．091—0．28μg／L）。不同断面河水汞含量均高于相应近岸井水汞含量。不同水体底泥中汞的形态分布一般顺序为：残渣态〉难氧化降解有机质结合态〉腐殖酸结合态〉碳酸盐和铁锰氧化物吸附态〉交换态〉易氧化降解有机质结合态〉水溶态。综合各项资料分析,认为漓江干流是桂林城市汞污染最大的汇。根据地表水环境质量标准（GB3838--2002）,仅汞而言,漓江水系均达到Ⅳ类水质标准（河水中汞含量≤1μg／L）。漓江支流汞污染高于干流,对干流存在较大的污染风险。  相似文献   

矿山投料井施工难点与对策          下载免费PDF全文

邱文权  彭金灶  陈惠明  吴灿辉 《探矿工程》2010,37(4):31-33

结合福建省武平某银多金属矿施工填充站TZK1、TZK2投料井工程,详细介绍了矿山投料井施工的难点与对策：通过对钻探设备的优化组合,结合钟摆钻具原理,辅以护壁堵漏,研制分离式注浆专用阀,顺利下入套管及注浆固井,圆满完成了该投料井工程的施工任务。  相似文献   

河南舞阳铁矿铁古坑矿段岩心钻探施工工艺   总被引：1，自引：0，他引：1       下载免费PDF全文

祁新堂 《探矿工程》2010,37(5):22-24

针对舞阳铁矿铁山矿床铁古坑矿段的复杂地层,详细介绍了在渣堆上钻探、堵漏等具体的施工技术措施,以期对今后的钻探施工有所指导。  相似文献   

地下连续墙技术在深基坑围护中的应用     

刘永杰  左新明  王建华 《探矿工程》2010,37(7):44-49

结合某高层建筑深基坑围护的工程实例,介绍了地下连续墙施工技术在深基坑围护工程中的具体应用,阐述了地下连续墙施工的工艺流程和技术要点,提出了施工的注意事项和特殊问题的预防处理方法。  相似文献   

A Bingham-plastic model for fluid mud transport under waves and currents     

刘春嵘  吴博  呼和敖德 《中国海洋工程》2014,28(2):227-238

Simplified equations of fluid mud motion, which is described as Bingham-Plastic model under waves and currents, are presented by order analysis. The simplified equations are non-linear ordinary differential equations which are solved by hybrid numerical-analytical technique. As the computational cost is very low, the effects of wave current parameters and fluid mud properties on the transportation velocity of the fluid mud are studied systematically. It is found that the fluid mud can move toward one direction even if the shear stress acting on the fluid mud bed is much smaller than the fluid mud yield stress under the condition of wave and current coexistence. Experiments of the fluid mud motion under current with fluctuation water surface are carried out. The fluid mud transportation velocity predicted by the presented mathematical model can roughly match that measured in experiments.  相似文献   

Dispersal of the Zhujiang River (Pearl River) derived sediment in the Holocene   总被引：2，自引：1，他引：1  

GE Qian  LIU J. P.  XUE Zuo  CHU Fengyou 《海洋学报(英文版)》2014,33(8):1-9

High-resolution Chirp profiling and coring reveals an elongated(ca. 400 km) Holocene Zhujiang River(Pearl River)-derived mud area(maximum thickness 20 m) extending from the Zhujiang River Delta, southwestward off the Guangdong coast, to the Leizhou Peninsula. Two depo-centers, one proximal and one distal, are identified. On the continental shelf off the west Guangdong Province, the mud is deposited in water depth shallower than 50 m; while to the southeast of the Zhujiang River Estuary, the mud area can extend to the-120 m isobath. A combined analysis with the stratigraphic sequences of other muddy deposits in the Western Pacific marginal seas(mainly Changjiang(Yangtze) and Huanghe(Yellow) Rivers derived) indicates that the initiation of the Zhujiang River muddy deposit can be further divided into two stages: Stage 1 is before the mid-Holocene sea-level highstand(ca. 7.0 cal. ka BP), the proximal mud was mostly deposited after 9.0 cal. ka BP, when the sea-level rose slowly after the Meltwater Pulse-1C; Stage 2, after the mid-Holocene sealevel highstand, clinoform developed on the continental shelf off the west Guangdong Province, extending ca. 400 km from the Zhujiang River Estuary. The proximal clinoform thins offshore, from ca. 10 m thickness around 5–10 m water depth to less than 1–2 m around 20–30 m water depth. In addition, we also find a developed distal clinoform in the east of the Leizhou Peninsula.  相似文献   

松辽盆地东南隆起区青山口组一段泥页岩地球化学特征及地质意义   总被引：1，自引：0，他引：1  

李翔  刘招君  孙平昌  李宝毅  柳蓉  张明明  甄甄  杨小红 《世界地质》2014,33(4):746-757

松辽盆地青山口组一段主要为暗色泥岩,并发育多层品质较好的油页岩。对盆地东南隆起区NGN1井泥岩系统取样测试,地球化学分析结果显示:w(Si O2)为44.88%~57.75%,w(K2O)一般比w(Na2O)高,w(Mg O+Fe2OT3)为4.5%~10.01%,表明泥岩中含有较多的含钾矿物和一定的铁镁质成分。样品微量元素PAAS标准化配分曲线显示样品中元素富集、亏损均呈现基本一致的趋势,表明泥岩沉积时期存在一种主要物源。稀土元素球粒陨石标准化后呈现出明显的右倾趋势和Eu的负异常,显示物源来自上地壳。泥岩CIA指数为48~62,Th/U值大都集中在1.48~4,表明泥岩源区经历了低等的风化作用;Th/Sc--Zr/Sc图解显示泥岩中的沉积碎屑没有经历沉积再循环,受原岩成分控制,表明地球化学数据可以进行物源类型和构造环境判断。根据原岩和构造背景判别图解,松辽盆地东南隆起区青一段泥岩物源主要为中—晚侏罗世中酸性喷发岩,并混有海西期和燕山期花岗岩;原岩的构造背景为大陆边缘造山运动形成的大陆岛弧。  相似文献   

岩溶峰丛洼地不同环境水土流失差异及防治研究——以广西果化岩溶生态研究基地为例   总被引：3，自引：0，他引：3  

罗为群  张辉旭  蒋忠诚  金克谟  李衍青  王志广 《地球学报》2014,35(4):473-480

与碎屑岩地区相比,特殊的岩溶水文地质结构,导致岩溶区存在不同的水土流失过程和特点,尤以峰丛洼地区最具代表性。通过广西平果县果化岩溶峰丛洼地土壤地表侵蚀和地下漏失的调查研究显示:洼地不同地貌部位水土流失差异较大,从山峰、垭口、山坡、山麓到洼地底部,土壤地下漏失模数分别为49.09 t/(km2·a)、212.06 t/(km2·a)、727.71 t/(km2·a)、1104.03 t/(km2·a)、909.11 t/(km2·a),分别占该点年均总土壤侵蚀模数的92.43%、96.24%、78.57%、70.88%和38.68%;不同土地利用方式下的土壤侵蚀存在差异,其土壤侵蚀模数大小依次为坡耕地苦丁茶地苏木林地灌草坡牧草地。通过对该地区水土流失防治及石漠化综合治理,山峰主要涵养水源林、山坡主要发展生态产业防治水土漏失、洼地修建排水系统工程得到良好的效果,治理区土壤侵蚀模数从2003年到2010年下降了65%。  相似文献   

真空预压法在珠江流域某冲填土场地的应用     

秦皎 《岩土工程技术》2014,(1):45-47,55

依托珠江流域某冲填土场地工程实例,介绍了真空预压法的施工参数及应用效果,另对“薄弱部位”泥浆搅拌桩密封墙处地层的强度进行了定量分析,结果表明真空预压法适用于此类场地,加固效果明显,但密封墙位置强度降幅较大,需采取换填等措施二次处理后才能使用,可为其他类似工程提供参考经验.  相似文献   

Mud dispersal across a Cretaceous prodelta: Storm‐generated,wave‐enhanced sediment gravity flows inferred from mudstone microtexture and microfacies     

A. Guy Plint 《Sedimentology》2014,61(3):609-647

Determining sediment transport direction in ancient mudrocks is difficult. In order to determine both process and direction of mud transport, a portion of a well‐mapped Cretaceous delta system was studied. Oriented samples from outcrop represent prodelta environments from ca 10 to 120 km offshore. Oriented thin sections of mudstone, cut in three planes, allowed bed microstructure and palaeoflow directions to be determined. Clay mineral platelets are packaged in equant, face‐face aggregates 2 to 5 μm in diameter that have a random orientation; these aggregates may have formed through flocculation in fluid mud. Cohesive mud was eroded by storms to make intraclastic aggregates 5 to 20 μm in diameter. Mudstone beds are millimetre‐scale, and four microfacies are recognized: Well‐sorted siltstone forms millimetre‐scale combined‐flow ripples overlying scoured surfaces; deposition was from turbulent combined flow. Silt‐streaked claystone comprises parallel, sub‐millimetre laminae of siliceous silt and clay aggregates sorted by shear in the boundary layer beneath a wave‐supported gravity flow of fluid mud. Silty claystone comprises fine siliceous silt grains floating in a matrix of clay and was deposited by vertical settling as fluid mud gelled under minimal current shear. Homogeneous clay‐rich mudstone has little silt and may represent late‐stage settling of fluid mud, or settling from wave‐dissipated fluid mud. It is difficult or impossible to correlate millimetre‐scale beds between thin sections from the same sample, spaced only ca 20 mm apart, due to lateral facies change and localized scour and fill. Combined‐flow ripples in siltstone show strong preferred migration directly down the regional prodelta slope, estimated at ca 1 : 1000. Ripple migration was effected by drag exerted by an overlying layer of downslope‐flowing, wave‐supported fluid mud. In the upper part of the studied section, centimetre‐scale interbeds of very fine to fine‐grained sandstone show wave ripple crests trending shore normal, whereas combined‐flow ripples migrated obliquely alongshore and offshore. Storm winds blowing from the north‐east drove shore‐oblique geostrophic sand transport whereas simultaneously, wave‐supported flows of fluid mud travelled downslope under the influence of gravity. Effective wave base for sand, estimated at ca 40 m, intersected the prodelta surface ca 80 km offshore whereas wave base for mud was at ca 70 m and lay ca 120 km offshore. Small‐scale bioturbation of mud beds co‐occurs with interbedded sandstone but stratigraphically lower, sand‐free mudstone has few or no signs of benthic fauna. It is likely that a combination of soupground substrate, frequent storm emplacement of fluid mud, low nutrient availability and possibly reduced bottom‐water oxygen content collectively inhibited benthic fauna in the distal prodelta.  相似文献