Associations and mobility of uranium in soils near a depleted uranium （DU） weapons testing site, SW Scotland     

Margaret C. Graham John G. Farmer Ian W. Oliver Angus B. MacKenzie Robert M. Ellam 《中国地球化学学报》2006,25(B08):112-112

Natural uranium has three isotopes, ^238U, ^235U and ^234U, with natural abundances of 99.27 atom %, 0.72% and 0.0055%, respectively. Only ^235U is fissile and the production of nuclear fuel and nuclear weapons involves enrichment of uranium in ^235U. This process also results in separation of ^234U from ^238U, leaving depleted uranium （DU）, with typical ^234U/^238U and ^235U/^238U activity ratios of about 0.19 and 0.013, respectively, as a waste product. The high density, high melting and boiling points and chemical stability of uranium and the availability of DU in relatively pure form mean that DU has many uses, including armour-piercing munitions. Such munitions have been developed in the UK since the 1960s and testing has been carried out by the Ministry of Defence （MoD） at firing ranges such as Dundrennan, SW Scotland and Eskmeals, NW England. The firing of DU munitions can result in the dispersion of DU and its combustion products （oxides） as aerosols or as larger fragments, with the potential for human exposure either directly at the site of detonation or via post-depositional migration in the environment. The aim of this work was to investigate the potential environmental mobility of DU by characterizing the associations of U in soil porewaters with increasing distance from a firing site. To this end, several soil cores located down-wind of the firing site at Dundrennan, near Kirkcudbright, SW Scotland, were collected in May 2006. These were sectioned on-site into 1- or 2-cm depth intervals and porewaters were isolated by centfifugation （10 minutes; 8873 g） on return to the laboratory. Following filtration through 0.2-micron cellulose nitrate filters, the porewaters were analyzed by ICP-QMS （U concentration） and ICP-OES （Fe, Al, Ca, Mg, Mn concentrations）. Sub-samples were also subjected to centrifugal ultrafiltration （100, 30, and 3 kD） and to gel electrophoretic fractionation （agarose; 0.045 M Tris-borate; 20 mA, 30 minutes）. Results showed that U was present at up to 4 μg/L in the soil porewater and that the associations of U varied with sample location and soil depth.  相似文献   

Possibility of degradation of phenylarsonic acid in the presence of ferrihydrite     

Yoko Shimamoto Yoshio Takahashi 《中国地球化学学报》2006,25(B08):114-114

Although inorganic species are predominant in natural systems, but there are many kinds of organoarsenic species such as methylated and phenylated arsenic compounds. Phenylarsonic acid （PA） is a degradation product of organoarsenics used for chemical warfare agents, which has been detected in well water at the disposal site of the agents in Japan. There are few reports studying behavior of PA in soil. In this study, PA was adsorbed onto ferrihydrite and its chemical forms were determined using high performance liquid chromatography connected to inductivity-coupled plasma mass spectrometry （HPLC-ICP-MS）. 100 mg/kg of PA was mixed with 0.03 g of 2-line ferrihydrite. For each suspension, pH was adjusted by HNO3 or NaOH. Each sample was incubated for more than 19 hours and the final pH was measured. After filtration, the chemical form of arsenic in the filtrate was measured using HPLC-ICP-MS. In addition, ferrihydrite separated by filtration was dissolved by 3 ml of 0.5 M HCI and the arsenic species in the solution was detected by HPLC-ICP-MS （column： Tosoh TSKgel SuperlC-AP, eluent： 0.01 M HNO3）. It was verified that PA is not degraded by heating in 0.5 M HCl solution. At pH 3.1, any arsenic compounds were not detected from the solution, because almost all arsenic species were adsorbed onto ferrihydrite at lower pH. At pH= 12, however, 7%-10% of inorganic arsenic was detected in the solution. In solid phase, there are some problems to determine the precise ratio of inorganic and organic species. When the solution includes Fe ion at 0.01 M level, the retention time of arsenic species drifted compared to those in standard solution, which makes it difficult to determine precisely the arsenic species adsorbed on ferrihydrite. Therefore, more study is needed to determine the ratio of inorganic and organic species in the system.  相似文献   

Assessment of marine pollution in Daya Bay, South China： Nutrients, heavy metals and persistent organic pollutants     

《中国地球化学学报》2006,25(B08):166-166

  相似文献   

DDT residue in soil and water in and around the abounded area of DDT manufacturing factory     

Mohammad Rasul Jan Mahmood A Khawaja Jasmin Sha Kashif Gul 《中国地球化学学报》2006,25(B08):182-182

Due to the persistent nature of DDT, a persistent organic pollutant and its adverse environmental and health impacts, the present study was undertaken to examine the residual DDT in and around DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. The factory was established in 1963 and remained in operation till 1994. Composite samples of soil, sediments and water were collected in and around the factory area, nearby DDT stores, main factory drain leading to river and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analysis. Physical parameters for the collected water samples measured were temperature, pH and conductance. Extraction of each sample for DDT analyses was carried out in triplicates using soxhlet extraction apparatus. The extract was transferred to well washed, clean; dry glass vial, sealed and put in the refrigerator. Gas Chromatograph with electron capture detector and capillary column was used for analysis. DDT in the samples was identified on the basis of their retention time and quantified on the basis of peak areas. It is evident from the analytical data obtained in the present study that both water and soil in and around the factory area are still contaminated with DDT, despite the closure of the factory since the past few years.  相似文献   

Occurrence of microorganic pollutants in the atmosphere of Singapore during haze and non-haze periods     

Rajasekhar Balasubramanian Chanbasha Basheer Kang Lisa Siao Wei See 《中国地球化学学报》2006,25(B08):183-183

Microorganic pollutants such as polycylic aromatic hydrocarbons （PAHs）, organochlorine pesticides （OCPs）, polychlorinated biphenyls （PCBs） and total petroleum hydrocarbons （TPHs） are known to be present in urban ambient air. These organic compounds are prone to atmospheric transport and deposition over long distances, thus enabling them to accumulate even in regions remote from their sources. Deposition from the atmosphere can be via direct deposition and exchange with crops that may be directly or indirectly ingested by humans. It can also take place via wet and dry deposition and air-water exchange. Following their deposition, these microorganic pollutants tend to accumulate in soils, sediments and in human and ecological food chains. There are many reports in the literature on the atmospheric concentrations of microorganic pollutants, but there are few reports and data in Asia. This study was performed in Singapore to determine the relative amounts of persistent organic pollutants and TPHs in ambient aerosols. One of the important sources of these organic compounds in Southeast Asia is thought to be biomass burning （vegetation fires）. Hence, air sampling was conducted during both smoke haze and non-haze periods. The data obtained from this study will be presented and discussed.  相似文献   

Water chemical behavior at Yangtze （Changjiang） River estuary     

Sivaji Patra Congqiang LIU Siliang LI Fushun WANG Baoli WANG 《中国地球化学学报》2006,25(B08):269-270

Geochemical cycling has received wide attention due to the need to understand the pathways of pollutants through our present environment. In this regard the Yangtze River plays a significant role in putting those pollutants into the East China SeafWorld Oceans. The Yangtze River is of high sedimentation rate and water discharge. The watershed covers variable climate regions from temperate to subtropical and from semiarid to humid. Twenty three （23） sampling locations at the estuary have been selected for understanding the dynamic relationships. The elements （Cl^-, SO4^2-, Na^＋, K^＋, and Ca^2＋） show conservative behavior during mixing of fresh water with saline water whereas Mg^2＋, Mn^2＋ show a non-conservative pattern . The relationships between Na^＋/SO4^2- and Cl^-/SO4^2- molar ratios show a mixing of more than two water sources.  相似文献   

紫色丘陵区不同土地利用方式下土壤活性有机碳垂直分布特征     

《山地学报》2006,24(B10):21-26

  相似文献   

马朗凹陷马1井储层长石中有机包裹体研究          下载免费PDF全文

张小青  伊海生  危国亮  张小芹 《沉积与特提斯地质》2005,25(4):83-86

根据对马朗凹陷马1井储层长石中有机包裹体的基本特征、均一温度、荧光及荧光光谱分析，得出有机包裹体均一温度为60～90℃．120～140℃，其对应的荧光颜色分别为黄色和蓝绿色。认为储层的油气运移经历了两期，第一期为烃类的主要运移、聚集期，油气为低成熟油；第二期为少量的烃类聚集，并判断出二叠系条湖组该段储层为油气产层。  相似文献   

北方某城市浅层地下水中有机污染物迁移转化的数值模拟研究   总被引：2，自引：1，他引：2       下载免费PDF全文

刘明柱  陈鸿汉胡丽琴 《中国地质》2005,32(3):507-511

在3次野外取水样分析的基础上，分析了研究区域有机污染特征，并根据室内实验和国内外文献资料所获取的参数，利用地下水模拟系统软件（GMS）对研究区三氯乙烯（TCE）和四氯乙烯（PCE）在地下水中的运移转化进行数值模拟研究，模拟结果表明：研究区地下水中TCE和PCE存在生物降解作用，但是反应速率很小，这表明在相当长的时间内，其浓度仍可能保持在相当的水平上。  相似文献   

中国西北内陆盆地水分垂直循环及其生态学意义   总被引：11，自引：0，他引：11       下载免费PDF全文

周爱国  马瑞  张晨 《水科学进展》2005,16(1):127-133

中国西北内陆盆地中的地下水系统,对维系其浅表水分、热量、盐分均衡以及地表的生态平衡、土壤的资源属性和局部地域气候相对稳定性具有不可或缺的调节作用,这种调节作用是通过饱和带水、包气带水(土壤水)、近地表大汽水和植物体内水("四水")之间的垂直循环来实现的.目前的相关研究主要侧重于地下水与地表植被类型间对应关系的统计分析,较少涉及水分运移的机制;而以水分垂直循环的动力学机制为研究对象的SPAC系统(土壤-植物-大气连续体),则对地下水的重视程度不够,且存在着尺度转换的困难,更为完整的应该是GSPAC系统(地下水-土壤-植物-大气连续体).干旱区内陆盆地地下水生态效应的研究需要开展以下的工作:"四水"垂直循环的动力学过程与机制研究,尤其是饱水带-包气带界面水、汽、热转化过程的研究;人类活动影响下地下水系统演化特征的研究,它不仅是实现水分垂直循环研究的最终目的——水资源合理开发利用的中间环节,更是将"四水"垂直循环这一微观水文循环过程与区域水文循环过程相结合,实现尺度转化的关键所在.  相似文献