改性氢氧化镁对地下水中铅镉的稳定化性能研究     

史弋  张梦玥  李博文  范娇  马秀兰 《世界地质》2015,34(1):254-258

为研究OH-缓释剂对铅、镉污染地下水修复的可行性,通过室内实验制备改性氢氧化镁,并对其去除地下水中Pb和Cd的性能进行研究。实验结果表明,重金属的稳定化机理主要为沉淀反应。在去除单一重金属(Pb或Cd)实验中,Pb和Cd的去除率都可达到99%以上,反应符合一级反应动力学,反应速率常数分别为0.173 7 min-1和0.003 7 min-1。改性氢氧化镁在处理Pb和Cd的复合污染时Pb优先于Cd反应,Pb的存在会对Cd的沉淀起到抑制作用。  相似文献   

Mired in the past — looking to the future: Geochemistry of peat and the analysis of past environmental changes     

Richard Bindler   《Global and Planetary Change》2006,53(4):209

Peat cores from ombrotrophic bogs have been used as a valuable archive to study environmental change for over a century. Much of this focus on the peat record has been on biological proxies of environmental change, such as pollen and peat-forming macrofossils, but there is growing interest in the geochemical record to study environmental changes. Several studies of long-term peat records in Europe have reconstructed past changes in atmospheric lead pollution, for example, and the general cohesiveness of the results and their agreement with known historical trends in metal production exemplify the best potential of peat geochemistry as an environmental archive. Based on the success with lead, a current emphasis in peat reconstructions is to assess the record of past mercury deposition and results thus far show generally consistent trends, e.g., a pre-anthropogenic mercury accumulation rate of about 0.5–1.5 μg Hg m^− 2 year^− 1. Despite this general consistency there is increasing concern that there may be diagenetic effects on the quantitative record of some metals, which can be inferred based on a strong relationship between mercury and other organically bound elements and proxies for peat decomposition (C/N ratio). However, it is possible that changes in decomposition and the alteration of some metal records could provide climatic information. A few recent studies show that closer examination of the geochemical matrix, in some cases along with biological proxies, can provide valuable information on landscape changes and climate; for example, partitioning metals into different weight fractions and source regions can be applied to climate studies. The best interpretations of the peat geochemical record in the context of environmental and climate change will likely come when geochemical and biological records are considered simultaneously.  相似文献   

Physico-chemical Speciation of Lead in South San Francisco Bay     

P.B. Kozelka  S. Sañudo-Wilhelmy  A.R. Flegal  K.W. Bruland 《Estuarine, Coastal and Shelf Science》1997,44(6):649-658

The speciation of lead at a site in the South San Francisco Bay was determined using a combination of physical size fractionation and electrochemical analyses. The ‘ total dissolvable ’ Pb was 8·1 nM from analysis of an acidified unfiltered sample. The ‘ dissolved ’ Pb was equal to 0·20 nM (41 ng l⁻¹), only 2·5% of the ‘ total dissolvable ’ Pb. The difference yielded the ‘ particulate ’ Pb equal to 7·9 nM (1·6 μg l⁻¹). Results from crossflow ultrafiltration indicated that almost all (0·19 nM) of the dissolved Pb was ‘ in solution ’ [<10K nominal molecular weight (MW)] and that colloidal Pb (10K MW to 0·2 μm)accounted for onlyc. 1% of the dissolved Pb at this station. This small concentration (0·01 nM) of colloidal Pb may be attributed to the low amount of organic carbon associated with colloid size fraction as determined by dissolved organic carbon analyses.The chemical speciation of lead was determined in the dissolved sample and ultrafiltered sub-sample. Differential pulse anodic stripping voltammetry (DPASV) on a thin mercury film (TMF) rotating glassy carbon disk electrode (RGCDE) was used to distinguish the kinetically labile inorganic species (Pb′) from the Pb-chelated by organic ligands (PbL_i). Lead titration results were similar for both samples revealing that Pb′, PbL_iand excess unbound ligands were present primarily in the ultrafiltrate, rather than in the colloidal phase. The titration data can be interpreted as dissolved Pb being influenced by two classes of Pb-binding ligands. In the dissolved sample, the concentration of the stronger class of ligands was [L₁]=0·89±0·35 nM, with a conditional stability constant ofK^cond_L1,Pb′=3±1×10¹⁰M⁻¹. The weaker class was [L₂]=12·8±1·9 nM, withK^cond_L1,Pb′=4±1×10⁸ M⁻¹. The presence of these ligands, in excess of the dissolved Pb, resulted in [Pb′]=7±2 pM and [Pb²⁺]=0·3 pM (62 pg l⁻¹). While less than 2·4% of the ambient Pb was ‘ in solution ’, it existed chiefly in the form of organic complexes with [PbL₁]=0·15 nM and [PbL₂]=0·03 nM. More significantly, there were large concentrations of unchelated Pb-binding ligands, (L_i′), available to buffer the free Pb²⁺concentration in the event of perturbations in dissolved Pb.  相似文献   

Effects of metals and sediment particle size on the species composition of the epifauna of Pinna bicolor near a lead smelter,Spencer Gulf,South Australia     

Trevor J. Ward  Peter C. Young 《Estuarine, Coastal and Shelf Science》1984,18(1):79-95

Pinna bicolor (Mollusca: Pelecypoda) were transplanted between four sites near a lead smelter. The species composition of their epifauna (sessile and mobile) was examined in relation to characteristics of both sediments and seston at the sites. Seventy-two taxa were distinguished in the epifaunal community. Substantial differences were found in the short-term sensitivity of some of the species to concentrations of Cd, Pb and Zn in sediments and to sediment particle size. The short-term sensitivity of many species to metals or sediment particle size explained their long-term distribution pattern. Twenty-three taxa were identified as significantly characterizing the faunal differences. Of these, eleven (four molluscs, four bryozoans, two barnacles and one ascidian) were affected by both sediment metal concentration and particle size, and eight (four molluscs, one bryozoan, one polychaete, one hydroid and one barnacle) were affected by metal contamination but not particle size. Of all fauna examined, the Bryozoa were the most metal-sensitive. Four species, Smittina raigii (Bryozoa), Galeolaria sp. 1 (Polychaeta), Epopella simplex (Cirripedia) and Monia ione (Pelecypoda) were identified by their short- and long-term sensitivity to metal contamination, and absence of sensitivity to sediment particle size, as suitable species for monitoring the effects of metal contamination on the epifauna. The implications of the results for toxicity-testing are discussed.  相似文献   

氢化物原子荧光光度法测定地球化学样品中的微量铅     

韦德平 《国土资源》1992,(4)

拟定了用铅空心阴极灯为激发光源,氢化物原子荧光光度法测定地球化学样品中微量铅的方法。在2％HCl-0.08％K_3[Fe(CN)_6]-2％KBH_4体系中,铅的测定灵敏度有明显地提高。该方法操作简便、快速、准确,检出限为8.89×10~(-9)g/ml,精密度为4.12％(n=11)。  相似文献   

Zinc, Lead and Cadmium Content in Meadow Plants and Mosses Along the M3 Motorway (Hungary)     

T. Naszradi  A. Badacsonyi  N. Németh  Z. Tuba  F. Batiĉ 《Journal of Atmospheric Chemistry》2004,49(1-3):593-603

The heavy metal content was investigated in meadow plants located in a cultivated area and situated along the M3 motorway (Hungary). In addition to the meadow plants used as passive bioindicators, active bioindicators were also exposed to examine the accumulation rate of air pollutants. Tortula ruralis (Hedw.) Geartn. ssp. ruralis was applied to monitor the status of the environment. Meadow plant samples were collected at distances of 5, 10, 25, 50 and 100 m from the motorway and moss samples were exposed at the same distances. The zinc, lead and cadmium content of meadow plants and moss samples were analysed by ICP spectrophotometry. It was found that the zinc, lead and cadmium contents of the meadow plants decreased as the distance increased from the motorway. There was a significant difference even between values measured at the distances of 5 m and 10 m. The heavy metal contents in the moss samples exceeded those of the meadow plants. The heavy metal content in moss samples decreased with distance from the motorway. On comparing the data with Hungarian standards, it was found that measured values did not exceed the maximum allowed concentration levels.  相似文献   

超大型会泽富锗铅锌矿复合成因   总被引：4，自引：0，他引：4  

薛步高 《云南地质》2006,25(2):143-159

会泽富锗铅锌矿。是近年老矿山深部找矿取得重大突破的典范,而其成因则是当前研究、讨论的热点。笔者认为该矿之形成,既非“MVT型”,亦非“VMS型”,而是与深部隐伏燕山期酸性岩有关的中温岩浆热液叠加、改造、富化的复成因矿床。自加里东期起长期处于张裂环境。深部昭通．弥勒硅镁层隆起,既是幔源玄武岩（热地幔柱）上涌的前奏,又为深部矿源上升创造畅通空间。与多旋回活动的小江深断裂相沟通的NE向矩形断裂网,是导矿、输矿、储矿的有利构造。继火山热液成矿之后,伴随燕山期褶皱、断裂和深部酸性岩浆的上升,发生第二期叠加矿化．矿石中伴生与酸性岩有关的元素组合．并以与酸性岩有关的锗富集为特征。  相似文献   

铅对不同土壤中青菜生长的影响     

汤莉莉  牛生杰  徐建强  晏培  杨雪贞  谢学俭 《南京气象学院学报》2008,31(1):104-108

采用盆栽试验,研究了南京和北京土壤中Pb污染对青菜生长的影响。结果表明：土壤质地对青菜生长有明显的影响;在土壤Pb含量低的处理水平下,对青菜的生长有一定影响;低含量范围内,青菜中Pb含量随土壤Pb处理含量的增加出现先升后降的变化趋势;在100mg／kg时,青菜的生长受到抑制,植株中Pb的含量高于对照组和200mg／kgPb处理。  相似文献   

Regional stratigraphy and distribution of epigenetic stratabound celestine, fluorite, barite and Pb–Zn deposits in the MVT province of northeastern Mexico     

Francisco González-Sánchez  Antoni Camprubí  Eduardo González-Partida  Rafael Puente-Solís  Carles Canet  Elena Centeno-García  Viorel Atudorei 《Mineralium Deposita》2009,44(3):343-361

Northeastern Mexico hosts numerous epigenetic stratabound carbonate-hosted low-temperature hydrothermal deposits of celestine, fluorite, barite and zinc-lead, which formed by replacement of Mesozoic evaporites or carbonate rocks. Such deposits can be permissively catalogued as Mississippi Valley-type (MVT) deposits. The deposits studied in the state of Coahuila are associated with granitic and metasedimentary basement highs (horsts) marginal or central to the Mesozoic Sabinas Basin. These horsts controlled the stratigraphy of the Mesozoic basins and subsequently influenced the Laramide structural pattern. The Sabinas Basin consists of ~6,000-m-thick Jurassic to Cretaceous siliciclastic, carbonate and evaporitic series. The MVT deposits are mostly in Barremian and in Aptian-Albian to Cenomanian formations and likely formed from basinal brines that were mobilized during the Laramide orogeny, although earlier diagenetic replacement of evaporite layers (barite and celestine deposits) and lining of paleokarstic cavities in reef carbonates (Zn–Pb deposits) is observed. Fluid inclusion microthermometry and isotopic studies suggest ore formation due to mixing of basinal brines and meteoric water. Homogenization temperatures of fluid inclusions range from 45°C to 210°C; salinities range from 0 to 26 wt.% NaCl equiv., and some inclusions contain hydrocarbons or bitumen. Sulfur isotope data suggest that most of the sulfur in barite and celestine is derived from Barremian to Cenomanian evaporites. Regional geology and a compilation of metallogenic features define the new MVT province of northeastern Mexico, which comprises most of the state of Coahuila and portions of the neighboring states of Nuevo León, Durango and, perhaps extends into Zacatecas and southern Texas. This province exhibits a regional metal zonation, with celestine deposits to the south, fluorite deposits to the north and barite and Zn–Pb deposits mostly in the central part.  相似文献   

广东云浮含Tl硫酸冶炼堆渣场土壤Tl污染的元素-Pb同位素示踪研究     

刘敬勇  常向阳 《地球化学》2009,38(3):251-261

利用元素总量和Pb同位素示踪技术对广东云浮硫酸厂含Tl黄铁矿冶炼堆渣场周围土壤中Tl的污染程度和迁移行为进行了研究。研究发现堆渣场周围土壤中Tl污染物主要集中于表层土壤约16．5cm深度内,并且表现出沿垂直方向向下迅速下降的特点。堆渣场周围土壤中Tl与Pb呈显著线性相关,表明自然条件下田与Pb在土壤中的迁移相似性,并且都以横向迁移为主。堆渣场固结层周围土壤至少44cm范围已经受到废渣中Tl释放的影响,Tl污染物平均下渗速率达到2．75cm／a。酸性雨水的淋滤作用及废渣自身不断酸化的特性是废渣中．Tl迁移释放入土壤的主要因素,土壤铁氧化物胶体及有机质是土壤对Tl产生吸附的主要载体。  相似文献