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1.
Hg、As、Sb是土壤和河流沉积物的常规测定项目。本文采用新型三通道原子荧光分析仪,建立了同时测定土壤和河流沉积物中这三种元素的新方法。通过优化仪器工作条件,选择合适的样品处置方法,得到Hg、As、Sb的检出限分别为0.03mg/kg、0.009mg/kg和0.03mg/kg,精密度分别为3.5%、7.8%和5.5%,准确度分别为95%～103%、91%～107%(加标回收率)和±6.4%。与现有测定方法相比,本方法的样品消化完全,实验简便,分析速度和准确度高,能充分满足分析要求。 相似文献
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氢化物—原子荧光法测定大洋沉积物中的砷 总被引：14，自引：0，他引：14
试验了常用酸及还原剂用量对测定Ａｓ的影响，选择了仪器的最佳工作条件，考察了大洋沉积物中主量及常见元素对测定的干扰情况，并给出了这些元素不干扰测定的允许存在量。方法用于测定海底沉积物标准样品，结果与标准值吻合，相对标准偏差（ｎ＝１２）小于５％。 相似文献
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铁盐絮凝法对阳宗海湖泊水体的除砷效果及底泥的稳定性考察 总被引：1，自引：0，他引：1
2008年,昆明阳宗海受到严重砷污染,砷浓度高达0.134 mg/L。项目组充分考虑其受污染水体容量大、砷浓度低的实际情况,提出了安全、廉价、高效的FeCl3絮凝法治理方案。实验室小试结果表明,提出的FeCl3絮凝法对As(Ⅲ)及As(V)均有理想的去除效果,并且湖水中大量存在的阴离子HCO-3可使治理过程中水体pH值基本保持不变。因此该方案摒弃了文献普遍报道所需要的预氧化及调节pH值的工艺步骤,将固体FeCl3·6H2O溶解、用湖水稀释后通过喷洒船将最终浓度为1%左右的FeCl3水溶液喷洒到湖面上,使湖水中的AsO3-4及AsO-2与FeCl3水解过程产生的Fe(OH)3胶体絮凝形成稳定的沉淀物被固定于底泥中。在对阳宗海进行降砷工程化治理期间,2009年11月-2010年9月砷浓度从0.117 mg/L快速下降到0.021 mg/L并可持续达到Ⅱ-Ⅲ类水标准(<0.05 mg/L),总除砷率高达 82.05%。沉积物中的As绝大部分以残渣态的形式被固定在沉积物中,生态风险很低。 相似文献
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Costa Larissa Mirlean Nicolai Quintana Guilherme Adebayo Segun Johannesson Karen 《Aquatic Geochemistry》2021,27(2):79-103
Arsenic (As), iron (Fe), and manganese (Mn) contents were measured in sediment nodules and associated pore waters obtained from sediment cores collected from a salt marsh on Pólvora Island (southern Brazil). Sediment cores were obtained when brackish water dominated the estuary, at two different environments: an unvegetated mudflat colonized by crabs (Neohelice granulata), and a low intertidal stand vegetated by Spartina alterniflora. We determined the percentage of nodules in each depth interval of the cores, along with redox potential, and As, Fe, and Mn contents of the nodules. The mineralogy of the nodules was investigated, and results showed they are mainly composed by quartz, phyllosilicates, and amorphous Fe–Mn oxides/oxyhydroxides. Pore water results showed that bioturbation by local crabs supports oxygen penetration to depths of ca. 25 cm below the salt marsh surface, with lower Fe contents in pore water associated with the brackish period. However, S. alterniflora growth appears to have a greater impact on sediment geochemistry of Fe, Mn, and possibly As due to sulfate reduction and the associated decrease in pore water pH. Higher Fe concentrations were observed in the pore waters during the period of brackish water dominance, which also corresponded to the S. alterniflora growth season. The study demonstrates that differences in geochemical conditions (e.g., Fe content) that can develop in salt marsh sediments owing to different types of bioirrigation processes (i.e., bioirrigation driven by crabs versus that related to the growth of S. alterniflora) play important roles in the biogeochemical cycling of As.
相似文献6.
Reactive Transport Modeling of Subaqueous Sediment Caps and Implications for the Long-Term Fate of Arsenic, Mercury, and Methylmercury 总被引：1，自引：0，他引：1
Brad A. Bessinger Dimitri Vlassopoulos Susana Serrano Peggy A. O’Day 《Aquatic Geochemistry》2012,18(4):297-326
A 1-D biogeochemical reactive transport model with a full set of equilibrium and kinetic biogeochemical reactions was developed to simulate the fate and transport of arsenic and mercury in subaqueous sediment caps. Model simulations (50?years) were performed for freshwater and estuarine scenarios with an anaerobic porewater and either a diffusion-only or a diffusion plus 0.1-m/year upward advective flux through the cap. A biological habitat layer in the top 0.15?m of the cap was simulated with the addition of organic carbon. For arsenic, the generation of sulfate-reducing conditions limits the formation of iron oxide phases available for adsorption. As a result, subaqueous sediment caps may be relatively ineffective for mitigating contaminant arsenic migration when influent concentrations are high and sorption capacity is insufficient. For mercury, sulfate reduction promotes the precipitation of metacinnabar (HgS) below the habitat layer, and associated fluxes across the sediment–water interface are low. As such, cap thickness is a key design parameter that can be adjusted to control the depth below the sediment–water interface at which mercury sulfide precipitates. The highest dissolved methylmercury concentrations occur in the habitat layer in estuarine environments under conditions of advecting porewater, but the highest sediment concentrations are predicted to occur in freshwater environments due to sorption on sediment organic matter. Site-specific reactive transport simulations are a powerful tool for identifying the major controls on sediment- and porewater-contaminant arsenic and mercury concentrations that result from coupling between physical conditions and biologically mediated chemical reactions. 相似文献
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Stefano Signorelli 《Environmental Geology》1997,32(4):239-244
Total arsenic contents were determined in volcanic gases by analysis of fumarolic condensates collected in the period 1984–1992
from different volcanoes around the world. Arsenic concentrations range from <0.006 to 30 μg/g. The highest values (1.2–30 μg/g)
were found at Vulcano, Aeolian Islands (southern Italy). The analytical data show that volcanic gases have a large variability
of arsenic contents possibly related to both the different physicochemical features of magma source and rock properties within
the volcanic system.
Received: 2 October 1996 · Accepted: 29 January 1997 相似文献
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从两个方面,即水环境中的泥沙问题和泥沙运动引起的环境问题出发,说明了环境中泥沙问题的普遍性,指出了结合泥沙运动研究环境问题和结合环境科学研究泥沙问题的重要性和必要性,并将这方面的工作概括为“环境泥沙学”.它研究受泥沙运动影响的污染物(包括泥沙颗粒本身)在环境中的迁移转化规律、控制及其应用,其核心是将水利工程科学主要是水力学、泥沙运动力学和环境科学的某些学科,如环境化学、环境地球化学等结合起来,研究与泥沙运动有关的环境问题,并对其研究内容和方法进行了探讨.这方面工作的深入,必然推动环境科学的加快发展,在某种程度上,也将推动泥沙科学的向前发展和丰富泥沙科学的研究内容. 相似文献
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微生物对砷的地球化学行为的影响--暨地下水砷污染机制的最新研究进展 总被引：7，自引：0，他引：7
砷在自然界中广泛存在,近年来砷污染对人类健康造成的危害越来越引人关注。微生物在自然界中长期与砷共存,进化出不同的生物转化机制,在自然水体中微生物主要参与砷的不同氧化价态之间的转化过程,即As(V)和As(III)之间的氧化还原作用。砷酸盐异化还原菌（Dissimilatory Arsenate Respiring Prokaryote, DARP）可以将As(V)还原为As(III),化能自养亚砷酸盐氧化菌（Chemoautotrophic Arsenite Oxidizer, CAO）和异养亚砷酸盐氧化菌（Heterotrophic Arsenite Oxidizer, HAO）可以将As(III)氧化为As(V)。这些砷代谢微生物在分类和代谢能力上都具有很大的多样性,它们广泛参与了砷的生物地球化学循环的关键步骤,对特定环境条件下砷的地球化学行为产生重要影响,进而参与了砷的全球循环。在盐碱湖莫诺（Mono）湖中砷的不同价态分层存在,CAO与DARP的紧密偶联共同参与了莫诺湖中的砷的地球化学循环。在孟加拉三角洲的地下含水层中,微生物参与了将砷从固相迁移到水相的关键步骤,最终导致了地下水中的砷污染。 相似文献
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The efficiency of Australian laterites in arsenic adsorption has been examined using three laterite samples collected from
different locations in South Australia. The characteristics such as electrical conductivity, pH, mineral compositions, and
isoelectric point of laterite samples have been measured. The laterite samples are mainly composed of iron and aluminum oxides,
and rutile (TiO2). Two batch experiments have been performed to compare the efficiencies of different laterites to remove AS (III) from water
at two different doses, and to examine whether pH influences arsenic adsorption. For 50 mg/l arsenic solution, at doses 1,000 g
(laterite)/l (arsenic solution) and 200 g/l, the laterites removed more than 97% and 87–97%, respectively. At the dose of
200 g/l, adsorption capacity has been found to be 200–243 mg/kg. Out of the laterite samples from three localities, the Kangaroo
Island laterite performed the best. This is probably related to its high content of gibbsite. It has been found that arsenic
adsorption by laterite is not significantly affected at the examined pH ranges of 4.7–10.0. 相似文献
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考察了在野外工作条件下，砷氢化物发生的各种影响因素，对氢化物发生-新银盐光度法测定砷的样品分解方法进行了简化和改进，配合自行研制的光导分光光度计，实现了砷的野外快速测定。样品经王水封闭溶解后，加入混合试剂以消除干扰，在调整酸度后，加入硼氢化钾将砷还原，呈AsH3选出，使硝酸银还原成胶体银，用光导分光光度计进行测定。方法检出限（3s）为0.20μg／g，加标回收率为92．0％～108％。方法经水系沉积物国家一级标准物质验证，分析结果与标准值相符，11次测定的相对标准偏差（RSD）小于10％。 相似文献
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电感耦合等离子体质谱法同时测定地质样品中痕量碘溴硒砷的研究：Ⅱ.土壤及沉积物标准物质分析 总被引：11，自引：8，他引：11
样品用碳酸钠和氧化锌混合熔剂半熔，热水提取，然后用强酸性阳离子交换树脂将阴离子形式存在的分析元素与溶液中大量钠、锌等阳离子分离，采用电感耦合等离子体质谱法直接同时测定溶液中的碘、溴、硒、砷。用0.07mol/L的氨水溶液清洗进样系统，有效减少了碘等元素的记忆效应和清洗时间。方法检出限（10σ，DF=100）溴、碘分别为0.15和0.028μg/g，砷、硒分别为0.04和0.004μg/g。用土壤和沉积物等地质标准物质分析验证了方法的准确度和精密度，绝大多数分析结果在标准值的允许误差范围之内。样品10次测定的RSD为0.8%～2.8%。 相似文献
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Sediment deposition from flocculated suspensions 总被引：3，自引：0，他引：3
KATE KRANCK 《Sedimentology》1975,22(1):111-123
Suspended sediment in coastal environments with high inorganic content have characteristic broad size distributions and are composed of both single grains and flocculated aggregates. These flocculated suspensions have stable size distributions the modal size of which is dependent on the modal size of the deflocculated single grain distributions. Comparison between theoretical settling speeds of quartz grains and the settling speed of particles in natural suspensions indicates that most grains smaller than the deflocculated single grain mode settle as part of flocs, whereas the particles larger than the mode settle as single grains. As a result the size distribution curves of sediment populations which settle out during consecutive intervals are composed of a modal peak of larger grains and a low flat portion of smaller grains and resemble the asymmetrical non-normal curves common for muddy sediments. 相似文献
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Sediment diffusion during overbank flows 总被引：5，自引：0，他引：5
JAMES E. PIZZUTO 《Sedimentology》1987,34(2):301-317
Distinctive overbank sediments deposited since European settlement on the floodplain of the Brandywine Creek, Pennsylvania, are used to calibrate and test a diffusion model of overbank deposition. The predictions of the model can be calibrated to reproduce the topography of the post-settlement lithosome with an average error of 7%. The model also correctly predicts the decrease in mean grain size away from the channel. The model greatly underestimates the ability of floodwaters to transport sand away from the channel. Apparently, sand is transported across the floodplain by bedload transport and by advective suspended sediment transport as well as by diffusion. If flow duration data for 1912–1981 and the present rating curve for the Brandywine Creek at Chadds Ford, Pennsylvania, are assumed to apply throughout the post-settlement period, the model may be used to estimate palaeohydraulic characteristics of post-settlement floods. Calculations indicate that 212 post-settlement floods covered the floodplain to an average depth of 1.6 m, transported an average excess suspended sediment concentration of 6200 ppm, and deposited an average thickness of 1.4 cm of sediment on levees next to the channel. 相似文献
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《International Journal of Coal Geology》2005,61(3-4):141-196
The review presented covers: (a) historical introduction; (b) some analytical comments; (c) some peculiarities of the As geochemistry in environment; (d) an estimation of coal Clarke value of As; (e) some coals enriched in As; (f) mode of As occurrence in coal; (g) factors influencing the As distribution in coal matter and coal bed; (h) genetic topics; (i) some topics related to environmental impact of As by the coal combustion.The World average As content in coals (coal Clarke of As) for the bituminous coals and lignites are, respectively, 9.0±0.8 and 7.4±1.4 ppm. On an ash basis, these contents are higher: 50±5 and 49±8 ppm, respectively. Therefore, As is a very coalphile element: it has strong affinity to coal matter — organic and (or) inorganic but obligatory authigenic. The coalphile affinity of As is like that for Ge or S.There is strong regional variability of As distribution due to geologic variability of the individual coal basins. For example, bituminous coals in Eastern Germany, Czech Republic and SE China are enriched in As, whereas the coals in South Africa or Australia are very depleted compared to coal Clarke of As. In general, some relationship exists between As content and its mode of occurrence in coals. Typically, at high As content, sulphide sites dominate (pyrite and other more rare sulphides), whereas at low As content, Asorg dominates, both being authigenic. A contribution of the terrigenic As (in silicates) is usually minor and of the biogenic Asbio (derived from coal-forming plants) is poorly known.Both organic and inorganic As can exist not only as chemically bound form but also in the sorbed (acid leacheable) arsenate form. With increasing coal rank, sorbed exchangeable arsenate content decreases, with a minimum in the coking coals (German data: the Ruhr coals).Relations of As content in coal to ash yield (or its partitioning in sink–float fractions) and to coal petrographic composition are usually complicated. In most cases, these relations are controlled by main site (form) of As — Aspyr or Asorg. If Aspyr dominates, an As accumulation in heavy fractions (or in high-ash coals) is observed, and if Asorg dominates, it is enriched in medium-density fractions (or low- and medium-ash coals). Arsenic is in part accumulated in the inertinite vs. vitrinite (Asorg ?).There are four genetic types of As accumulation on coal: two epigenetic and two syngenetic: (1) Chinese type—hydrothermal As enrichment, sometimes similar to known Carlin type of As-bearing telethermal gold deposits; (2) Dakota type—hypergene enrichment from ground waters draining As-bearing tufa host rocks; (3) Bulgarian type—As enrichment resulting from As-bearing waters entered coal-forming peat bogs from sulphide deposit aureoles; (4) Turkish type—volcanic input of As in coal-forming peat bog as exhalations, brines and volcanic ash.During coal combustion at power plants, most of the initial As in coal volatilizes into the gaseous phase. At the widely used combustion of pulverized coal, most of Asorg, Aspyr and “shielded” As-bearing micromineral phases escape into gaseous and particulate phase and only minor part of Asclay remains in bottom ash. The dominant fraction of escaping As is in fly ash. Because 97–99% of the fly ash is collected by electrostatic precipitators, the atmospheric emission of As (solid phase and gaseous) is usually assumed as rather minor (10–30% from initial As in coal). However, fly ash disposal creates some difficult environmental problems because it is potentially toxic in natural waters and soils. The As leaching rate from ash disposal is greatly controlled by the ash chemistry. In natural environment, As can be readily leached from acid (SiO2-rich) bituminous coal ashes but can be very difficult from alkali (CaO-rich) lignite ashes.If the Aspyr form dominates, conventional coal cleaning may be an efficient tool for the removing As from coal. However, organic-bound or micromineral arsenic (“shielded” grains of As-bearing sulphides) are not removed by this procedure.Some considerations show that “toxicity threshold” of As content in coal (permissible concentration for industrial utility) may be in the range 100–300 ppm As. However, for different coals (with different proportions of As-forms), and for different combustion procedures, this “threshold” varies. 相似文献