利用黏土矿物计算背景值评估沉积物重金属污染

综合考虑样品性质及粒度的影响,提出利用黏土矿物计算背景值的方法。实例研究表明,研究区沉积剖面不同深度样品的背景值存在一定的差异。将实测值与背景值之比视为富集因子,发现As、Cr、Cu在剖面的中下部弱富集;Pb在剖面中部弱富集;Zn与Cd在剖面的不同位置的富集程度变化较大,在中部显著富集,表层及底部中度富集。与传统方法相比,该方法综合考虑了粒度和样品性质的影响,并且可以计算出不同位置样品的背景值,使得评估结果更加准确。     

Impact of AMD on water quality in critical watershed in the Hudson River drainage basin: Phillips Mine,Hudson Highlands,New York

A sulfur and trace element enriched U–Th-laced tailings pile at the abandoned Phillips Mine in Garrison, New York, releases acid mine drainage (AMD, generally pH < 3, minimum pH 1.78) into the first-order Copper Mine Brook (CMB) that drains into the Hudson River. The pyrrhotite-rich Phillips Mine is located in the Highlands region, a critical water source for the New York metro area. A conceptual model for derivation/dissolution, sequestration, transport and dilution of contaminants is proposed. The acidic water interacts with the tailings, leaching and dissolving the trace metals. AMD evaporation during dry periods concentrates solid phase trace metals and sulfate, forming melanterite (FeSO₄·7H₂O) on sulfide-rich tailings surfaces. Wet periods dissolve these concentrates/precipitates, releasing stored acidity and trace metals into the CMB. Sediments along CMB are enriched in iron hydroxides which act as sinks for metals, indicating progressive sequestration that correlates with dilution and sharp rise in pH when mine water mixes with tributaries. Seasonal variations in metal concentrations were partly attributable to dissolution of the efflorescent salts with their sorbed metals and additional metals from surging acidic seepage induced by precipitation.     

湖南锡矿山土壤重金属污染评价

在前人工作的基础上,运用地质累积指数等环境地球化学研究的方法,对锡矿山土壤及其农作物中重金属污染进行了分析与评价.结果表明: (1)土壤中以Sb、Hg、Cd污染最为严重,其污染程度达强度以上;Zn、Cu、As、Pb次之,Cr未受到污染. (2)萝卜中元素的生物吸收系数顺序为Zn＞Cd＞Pb=As＞Cu＞Sb＞Hg＞Cr,其吸收程度与土壤污染程度并不一致,除与土壤中元素的浓度有关外,且受元素的生物吸收能力的控制.     

Micro-scale sulfur isotope and chemical variations in sphalerite from the Bleiberg Pb-Zn deposit,Eastern Alps,Austria

The Bleiberg Pb-Zn deposit in the Drau Range is the type locality of Alpine-type carbonate-hosted Pb-Zn deposits. Its origin has been the subject of on-going controversy with two contrasting genetic models proposed: (1) the SEDEX model, with ore forming contemporaneously with sedimentation of the Triassic host rocks at about 220 Ma vs. (2) the epigenetic MVT model, with ores forming after host rock sedimentation at about 200 Ma or later. Both models assume that, on a deposit or even district scale, a fixed paragenetic sequence of ore minerals can be established. The results of our detailed petrographic, chemical and sulfur isotope study of two key ore-samples from two major ore horizons in the Wetterstein Formation at Bleiberg (EHK02 Erzkalk horizon and Blb17 Maxer Bänke horizon) demonstrate that there is no fixed paragenetic sequence of ore minerals. Small-scale non-systematic variations are recorded in textures, sphalerite chemistry and δ³⁴S. In each sample, texturally different sphalerite types (colloform schalenblende, fine- and coarse-grained crystalline sphalerite) co-occur on a millimeter to centimeter scale. These sphalerites represent multiple mineralization stages/pulses since they differ in their trace element inventory and in their δ³⁴S. Nonetheless, there is some correspondence of sphalerite micro-textures, sulfur isotope and chemical composition between the two samples, with microcrystalline colloform schalenblende being Fe-rich, having high Fe/Cd (15 and 9, respectively) and a light sulfur isotope composition (δ³⁴S −26.0 to −16.2‰). Cadmium-rich and Fe-poor sphalerite in both samples has relatively heavier sulfur isotope composition: in sample EHK02 this sphalerite has Fe/Cd of ∼0.5 and δ³⁴S from −6.6 to −4.6‰; in sample Blb17 Fe/Cd is ∼0.1 and δ³⁴S ranges from −15.0 to −1.5‰. Barite, which is restricted to sample EHK02, has δ³⁴S ≈ 17‰. The large variations in δ³⁴S recorded on the mm to cm-scale is consistent with variable contributions of reduced sulfur from two different sulfur reservoirs. The dominant reservoir with δ³⁴S values <−20‰ likely results from local bacteriogenic sulfate reduction (BSR), whereas the second reservoir, with δ³⁴S about −5‰ suggests a hydrothermal source likely linked with thermochemical sulfate reduction (TSR). Based on this small- to micro-scale study, no simple, deposit-wide paragenetic and sulfur isotope evolution with time can be established. In the Erzkalk ore (sample EHK02) an earlier Pb-Zn-Ba stage, characterized by heavy sulfur isotope values, is succeeded by a light δ³⁴S-dominated Zn-Pb-F stage. In contrast, the several mineralization pulses identified in the stratiform Zn-Pb-F Maxer Bänke ore (sample Blb17) define a broad trend to heavier sulfur isotope values with time. The interaction documented in these samples between two sulfur reservoirs is considered a key mechanism of ore formation.     

Heavy metal transport in large river systems: heavy metal emissions and loads in the Rhine and Elbe river basins

Pollutant transport and management in the Rhine and Elbe basins is still of international concern, since certain target levels set by the international committees for protection of both rivers have not been reached. The analysis of the chain of emissions of point and diffuse sources to river loads will provide policy makers with a tool for effective management of river basins. The analysis of large river basins such as the Elbe and Rhine requires information on the spatial and temporal characteristics of both emissions and physical information of the entire river basin. In this paper, an analysis has been made of heavy metal emissions from various point and diffuse sources in the Rhine and Elbe drainage areas. Different point and diffuse pathways are considered in the model, such as inputs from industry, wastewater treatment plants, urban areas, erosion, groundwater, atmospheric deposition, tile drainage, and runoff. In most cases the measured heavy metal loads at monitoring stations are lower than the sum of the heavy metal emissions. This behaviour in large river systems can largely be explained by retention processes (e.g. sedimentation) and is dependent on the specific runoff of a catchment. Independent of the method used to estimate emissions, the source apportionment analysis of observed loads was used to determine the share of point and diffuse sources in the heavy metal load at a monitoring station by establishing a discharge dependency. The results from both the emission analysis and the source apportionment analysis of observed loads were compared and gave similar results. Between 51% (for Hg) and 74% (for Pb) of the total transport in the Elbe basin is supplied by inputs from diffuse sources. In the Rhine basin diffuse source inputs dominate the total transport and deliver more than 70% of the total transport. The diffuse hydrological pathways with the highest share are erosion and urban areas. Copyright © 2002 John Wiley & Sons, Ltd.     

原子荧光法测定天然矿泉水及地下水中的痕量锗

将地下水及矿泉水水样蒸发浓缩后,于10％磷酸介质中,利用无色散原子荧光法的原理,选择了XDY—Ⅱ型原子荧光光度计仪器的最佳工作条件,试验了各种条件对锗测定结果的影响。测定结果表明,该方法的检出限为6.69μg/l,相对标准偏差为4.5％,锗的回收率为96.45％—105.0％。本法快速、灵敏、准确,可用于大批量天然矿泉水及地下水中痕量锗的测定。     

表生地球化学研究若干方面现状

表生地球化学研究十分广泛。表生地质地球化学的研究包括有表生地球化学过程中各种动力学模型的研究，微生物对各种元素地球化学循环的控制作用及机理研究，岩石风化过程中定量指标的研究与应用，稀土元素在表生作用过程中的地球化学行为及有机质在表生矿产特别是金属矿产成矿机制中的作用的研究。上述诸方面的研究近年来已取得了不少新的成果，对表生矿产的形成机制及合理地开发和利用作出了应有的贡献。     

广东南部地理景观中土壤重金属垂直分异及其地球化学分层性

本文研究热带亚热带土壤中重金属分布的垂直分异及其分层性特征.土壤剖面中,水溶态、可交换态和有机结合态的重金属浓度自上层向底层降低.水溶态和有机结合态重金属的分布与有机质一致,而与pH值相反.Fe-Mn氧化物结合态的重金属分布与粘粒一致.残渣态分布的差异极小.     

Groundwaters of Florence (Italy): Trace element distribution and vulnerability of the aquifers

Geochemical and hydrogeological research has been carried out on 109 wells in the alluvial plain of Florence, in order to evaluate conductivity and main chemistry of ground waters, the pattern of some possible pollutant chemical species (Fe, Mn, Cr, Cu, Pb, Zn, NO₂, NO₃), and the vulnerability of the aquifers. The plain is made up of Plio-Quaternary alluvial and lacustrine sediments for a maximum thickness of 600 m. Silts and clays, sometimes with lenses of sandy gravels, are dominant, while considerable deposits of sands, pebbles, and gravels occur along the course of the Arno river and its tributary streams, and represent the most important aquifer of the plain. The groundwaters analyzed belong to this aquifer or to the smaller ones, hosted in the gravel lenses. Most waters show conductivity values around 1000–1200 S, and almost all of them have an alkaline-earth-bicarbonate chemical character; these features are consistent with the mainly calcareous lithology of the aquifers. In the western areas a higher salt content of the groundwaters is evident, probably related to the presence of industrial activities which use water desalinators. Heavy metal and NO₂, NO₃ analyses point out that no important pollution phenomena affect the groundwaters; all the mean values of the chemical considered species are below the maximum admissible concentration (MAC) fixed by the European Community for drinkable waters. Nevertheless, some anomalies of NO₂, NO₃, Fe, Mn, and Zn are present in the plain. Apart from Mn, which seems to be released by certain calcareous gravels, the other anomalies have a local influence, since they disappear even in the nearest wells. The most plausible causes can be recognized in losses of the sewage system (NO₂=3–4 mg/t); use of nitrate compounds in agriculture (NO₃=60–70 mg/l); oxidation of well pipes (Fe 20 mg/l; Zn 6 mg/l). As regards Cr, Cu, and Pb, all the observations are below the MAC; therefore, the median values of < 3, 3.9, and 1.1 g/l, respectively, could be considered reference concentrations for groundwaters circulating in calcareous lithotypes, under undisturbed natural conditions. Finally, a map of vulnerability related to the most superficial and important aquifer has been elaborated on the basis of thickness and permeability of the covers. The map shows that the areas near the Arno river are highly vulnerable, for the minimum thickness (or lacking) of sediments covering the aquifer. On the other hand, in the case of pollution, several factors not considered in the map could significantly increase the self-purification capacity of the aquifer, such as the dilution of groundwaters caused by the feeding of the rivers, the bacteria oxidation of nitrogenous species, and the sorption capacity of clay minerals and organic matter with respect to trace metals.     

Petrologic and geochemical links between the post-collisional Proterozoic Harney Peak leucogranite, South Dakota, USA, and its source rocks

The Proterozoic terrane of the Black Hills, South Dakota, includes the composite Harney Peak leucogranite and associated pegmatites that were emplaced into metamorphosed pelites and graywackes. Available dates indicate that granite generation post-dated regional metamorphism and deformation that have been attributed to collision of the Wyoming and Superior cratons at 1760 Ma. Previous radiogenic and stable isotope work indicates that the exposed metasedimentary rocks are equivalent to sources of the leucogranites. In this study, whole rock and mineral compositions of the metasedimentary rocks were used to calculate the likely average residue mineralogies and melt fractions that would be generated by muscovite dehydration melting of the rocks. These were then used to model observed trace element compositions of the granites using published mineral/melt distribution coefficients. Model trace element melt compositions using pelitic and graywacke protoliths yield similar results.

The models reproduce well the observed depletion of transition metals and Ba in the granites relative to metasedimentary protoliths. The depletion is due mainly to high proportion of biotite with variable amounts of K-feldspar in the model residue. Sr is also depleted in the granites compared to source rocks, but to a lesser relative extent than Ba. This is because of the low biotite/melt distribution coefficient for Sr and because high proportion of plagioclase in the residue is compensated by high Sr concentrations in protoliths. Rubidium, Cs and Ta behaved as slightly compatible to incompatible elements, and therefore, were not strongly fractionated during melting. Of the considered elements, only B appears to have been highly incompatible relative to residue during melting. The protoliths had sufficient B to allow tourmaline crystallization in those parts of the Harney Peak Granite in which Ti concentration was sufficiently low not to enhance crystallization of biotite.

The reproducibility of observed trace element concentrations in the Harney Peak Granite by the models supports the often made proposition that metapelites and metagraywackes are common sources for leucogranites. This argues against mass input from the mantle into metagraywacke and metapelitic crustal sources or melting of amphibolites to generate the post-collisional Harney Peak and other similar peraluminous granite suites.