Geochemistry of soils derived from black shale, central Hunan, China     

Bo PENG Shurong XIE Meilian XIAO Zhi SONG 《中国地球化学学报》2006,25(B08):85-86

The black shale formed under anoxic conditions usually contains high concentrations of many metals. Weathering of such black shale might cause the emission of many metals. Moreover, soils derived from black shale （SBS） are believed to be affected by black shale weathering. In recent years, many studies such as Lee et al. （2002）, Woo et al. （2002）, Fang et al. （2002）, Pasava et al. （2003）, and Peng et al. （2004） have approached the heavy metal contaminations of SBS, but systematical geochemical study is rare. Presently, the SBS and its corresponding black shales （CBS） were both sampled from central Hunan （China）, and analyzed for a large number of elements, using an Elan6000 ICP-MS/AES machine at Guangzhou Institute of Geochemistry, CAS. In this paper, some preliminary results are reported. The analytical results show that the SBS in central Hunan contains very high concentrations of heavy metals such as Co, Cu, Hg, Mo, Pb, Zn, U, Th, Sb, T1, Cd, Cr, Sc, V, Sn, As, Se, and Ni.  相似文献   

Selenium contamination in the Colorado River Basin, western USA： Remediation by leaching and nanof＇dtration membranes     

YousifK. Kharaka Evangelos G. Kakouros James J. Thordsen David L. Naftz 《中国地球化学学报》2006,25(B08):100-101

Selenium （Se） is an essential micronutrient to biota, but can become a potent toxicant at elevated concentrations. The natural sources and chemical properties of Se species make the boundary between deficiency and toxicity narrow for some biota, with both phenomena common around the globe. Large areas of farmland in the Colorado River Basin （CRB） generate salinized drainage water with Se concentrations much higher than 5 μg/L, the U.S. Environmental Protection Agency chronic water-quality criterion for the protection of aquatic life. We have carried out detailed field and laboratory studies to investigate Se geochemistry and remediation in two of these areas： the Middle Green River Basin, Utah and the Salton Sea Basin, California, located respectively in the Upper and Lower CRB. Results from these and other studies show that approximately 90% of the dissolved Se in the Colorado River and its tributaries originally is derived from the Upper Cretaceous Mancos Shale and equivalent pyritic marine units that outcrop in the Upper CRB. Selenium is mobilized commonly by biogeochemical oxidation of this pyritic shale and is concentrated mainly as selenate （SeO4^2-） in soils and agricultural drainage water of dry climates by evaporation. Minor （0%-5%） amounts of Se are present as the selenite species （HSeO3^-） and （SEO3^2-）, but these species and the more reduced species, elemental Se （SeO） and selenide （Se^2-）, have much lower solubility and/or have high sorptive affinity towards organic matter, clay minerals and iron oxyhydroxides. The concentration of dissolved Se （-2.5 μg/L） and salinity in the Lower Colorado River water are among the highest of the world major rivers. Because of low precipitation （7 cm/a） and extreme evapotranspiration （-1.8 m/a） rates in the Salton Sea Basin, California, Se values in irrigation water imported from the Colorado River increase to 〉300 μg/L in drainage wastewater. Removal of Se from contaminated wastewater by nanofiltration membranes was demonstrated in laboratory and pilot-scale field experiments.  相似文献   

Research on soil erosion prediction of highway rebuilding project in Tibet     

《中国地球化学学报》2006,25(B08):108-109

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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   

Effects of low molecular weight organic acids on sorption and desorption behavior of p-chlorophenol by yellow earth     

Daoyong ZHANG Xiangliang PAN Shuimu LIAO Chenglin HUANG Jingmei ZHANG 《中国地球化学学报》2006,25(B08):133-133

Low molecular weight organic acids （LMWOAs） are important components of root exudates. They play an important role in immobilizing and remobilizing contaminants in rhizospheric soil. Effects of four LMWOAs on the sorption and desorption behavior of p-chlorophenol by yellow earth was studied in batch mode. The results showed that the previous application of LMWOAs to enhanced adsorption capacity of p-chlorophenol of the soil in the order of maleic acid〉malic acid〉oxalic acid〉citric acid. However, when LMWOAs were applied to soil where p-chlorophenol had been previously adsorbed, substantial p-chlorophenol was desorbed from soil by oxalic acid, whereas citric acid, malic acid and maleic acid didn＇t desorb as much p-chlorophenol from soil as deionized water.  相似文献   

Analysis of the effect of geology, soil properties, and land use on groundwater quality using multivariate statistical and GIS methods     

Jin-Soo Lee Kyung-Seok Ko Tong-Kwon Kim Jae Gon Kim Seong-Hyun Cho In-Suk Oh 《中国地球化学学报》2006,25(B08):152-152

The regional survey of groundwater used as a small water supply system was performed to know the effect of geology, soil properties and land use on groundwater quality at Nonsan City, Korea. A total of 126 groundwater samples were collected and analyzed at the study area. The multivariate statistical methods, principal components analysis and discriminant analysis, and GIS technique were used for the quantitative interpretation of groundwater quality. The study area is mainly composed of Precambrian gneiss, Jurassic granite, and Cretaceous volcanics, and metasedimentary rocks of the Ogcheon zone. The land use was grouped as paddy, upland, grassland, resident, point source, industrial area, and water system. The soil properties were classified as 4 major groups, Entisols, Alfisols, Inceptisols, and Ultisols, by the degree of development, and reclassified as 11 subgroups. The modified and simplified geologic map, soil map, and land use map were made by using ARCGIS soft-ware. The area of geology, soil property, and land use affecting the groundwater quality for each well were also calculated by ARCGIS soft-ware to acquire the quantitative parameters for multivariate statistical analysis. The monitoring results of groundwater in the study area showed that 13%-21% of the groundwater samples exceeded the portable water guideline and the main causes were turbidity, bacteria, arsenic and nitrate-N. The spatial distribution of each component showed the close relationship between groundwater quality and geology reflecting the topography, land use.  相似文献   

长白山北坡垂直植被带表土植硅体组合研究   总被引：3，自引：0，他引：3  

张新荣  胡克  介冬梅 《地球学报》2006,27(2):169-173

长白山垂直分布的植被是欧亚大陆从温带到寒带植被水平地带性的缩影。对其北坡不同海拔高度植被带土壤中的植硅体进行初次研究,结果发现,该山北坡海拔700m到2630m的土壤中发育了形态和数量丰富的植硅体。不同植被带植硅体组合的含量各不相同,主要特征表现为随海拔升高示冷型的植硅体含量整体呈上升趋势,而示暖型的植硅体含量整体呈下降趋势。温泉附近土壤中的植硅体则表现出明显的与其上下相邻地点不同的特点。它对中国东北第四纪沉积物中植硅体组合的研究及第四纪古植被和古环境的重建可提供重要的基础性资料。  相似文献   

重庆金佛山表层岩溶生态系统土壤的CO2释放规律   总被引：2，自引：2，他引：2  

李林立  向颢  况明生  谢世友  张远瞩  蒋勇军  刘玉 《地球学报》2006,27(4):329-334

采用碱溶液吸收法通过对重庆金佛山林地、裸地表层岩溶生态系统土壤CO2释放量进行野外监测,研究了影响土壤CO2释放量变化的主要因素,揭示土壤CO2释放变化规律。土壤CO2释放量的变化主要随着温度而变化,即气温降低,土壤CO2释放量减少,在昼夜时段,土壤CO2也随温度而变化,但相比温度变化有明显滞后性;降雨对土壤CO2释放有比较复杂的影响,但非简单的线性相关;同时植被也会影响到土壤CO2的释放,总体上,相比裸地而言,林地的土壤CO2的释放量大,但在不同时间段内土壤CO2释放强度与气温的关系有较大差异。一天时间段内林地土壤CO2释放强度与温度的关系较裸地灵敏,这是因为林地本身生物量大,对温度反应敏感,温度很小的变化就能引发土壤CO2释放量的大幅度地改变。而在以月为单位观测时间段时,裸地土壤CO2释放强度与气温的关系较林地灵敏,这可能是因为植被覆盖减缓气温对土温的影响,对土温有较强的调节作用。这种不同植被系统下,在不同时段土壤的CO2释放量动态差异在讨论岩溶作用与碳循环时应充分注意。  相似文献   

大兴安岭火烧迹地土壤动物生态地理分析   总被引：20，自引：2，他引：20  

张雪萍  张淑花  李景科 《地理研究》2006,25(2):327-334

不同恢复年份森林火烧迹地的土壤动物群落特征明显不同。火烧过后的前1³年,大型土壤动物的种类和数量很少,特别是常见类群中的线蚓所占的比例很小,但运动能力较强的蜈蚣、蜘蛛等所占比例较高。火烧3⁵年后,土壤中线蚓数量才逐渐增多并趋于稳定。中小型土壤动物中的原尾虫只出现在16年迹地和对比样地中,表明原尾虫确是稳定生境的指示动物。火烧过后,土壤环境中最先侵入的是运动能力较强的大型土壤动物,之后中小型土壤动物才逐渐得到恢复。火烧后6⁷年是中小型土壤动物发展的盛期,随后土壤动物种类和数量开始减少并趋于稳定。火烧的强度对土壤动物群落的恢复有一定的影响,轻度火烧影响地区的土壤动物恢复较快,经过6⁷年,土壤动物种类和数量能超过未受火烧影响的地区;而中、重度火烧地区,土壤动物恢复到正常水平则需要超过16年的更长的时间。  相似文献