Organic complexation and translocation of ferric iron in podzols of the Negro River watershed. Separation of secondary Fe species from Al species

The development of podzols in lateritic landscapes of the upper Amazon basin contributes to the exportation of organic carbon and associated metals in the black waters of the Negro River watershed. We have investigated the distribution of Fe^III in the clay-size fraction of eight organic-rich horizons of waterlogged plateau podzols, to unravel the weathering conditions and mechanisms that control its transfer to the rivers. The speciation and amount of Fe^III stored in residual mineral phases of laterites, or bound to organic compounds of weakly and well-expressed podzols, were determined by electron paramagnetic resonance spectroscopy combined with chemical analyses.Reducing conditions restrict the production of organo-Fe complexes in the subsoil B-horizons of waterlogged podzols and most of the Fe²⁺ released from the dissolution of Fe-oxides is exported to the rivers via the perched groundwater. However, significant amounts of diluted Fe^III bound to organic ligands (Fe^III_OM) and nano Fe-oxides are produced at the margin of the depression in the topsoil A horizons of weakly expressed podzols due to shorter periods of anoxia. The downward translocation of organically bound metals from topsoil A to subsoil B-horizons of podzols occurs in shorter distances for Fe than it does for Al. This separation of secondary Fe species from Al species is attributed to the physical fractionation of their organic carriers in texture contrasted B-horizons of podzols, as well as to the effect of pH on metal speciation in soil solutions and metal binding onto soil organic ligands (mostly for Al). This leads us to consider the topsoil A horizons of weakly expressed podzols, as well as the subsoil Bh horizon of better-expressed ones, as the main sources for the transfer of Fe^III_OM to the rivers. The concentration of Fe^III_OM rises from soil sources to river colloids, suggesting drastic biogeochemical changes in more oxygenated black waters of the Negro River watershed. The contribution of soil organic matter to the transfer of Fe to rivers is likely at the origin of the peculiar Fe isotope pattern recently recognized in podzolic environments.     

印尼苏拉威西岛红土型镍矿的高效快速勘查模式

金属镍是我国紧缺资源之一,印度尼西亚拥有丰富的红土型镍矿,但是由于国外开采,在矿业政策、技术条件、气候条件上面临很多挑战,实施高效、快速、低成本勘探是解决这些问题的根本途径.文章以印尼苏拉威西岛的一个红土型镍矿勘查区为例,应用高精度磁法勘探,通过分析勘查区磁性特征圈定勘探靶区;对实验室和X-荧光仪分析的样品数据进行一元回归分析,将手持X-荧光分析仪成功应用于镍矿体的现场圈定,从而建立了红土型镍矿的高效、快速、低成本的勘查模式.     

世界红土型镍矿的资源分布及勘查、开发利用现状

目前世界上最具开发利用价值的镍矿床类型为岩浆硫化镍矿床和红土型镍矿床。本文在全面收集、整理和综合世界红土型镍矿相关资料的基础上, 对世界红土型镍矿的资源概况、地理分布、地质特征以及勘查和开发利用现状进行了系统的分析与阐述, 文章对我国地勘单位和矿业企业走出去勘查和开发利用国外红土型镍矿资源具有现实的借鉴和指导意义。     

Lateritic nickel deposits of Brazil

Many nickel deposits are known in Brazil, accounting for about 350 · 10⁶ tons of ore with an average of 1.5% Ni. All are of the lateritic type. These deposits are scattered throughout the country, being rarer in the Northeastern Region and in the South, below 25 °S latitude. They are mainly associated with mafic-ultramafic massifs of large dimensions and ultramafic alkaline complexes, and occur in climatic regions of contrasting seasons. The weathering profile developed over the fresh rock consists, from bottom to top, of the following horizons: altered rock, coarse saprolite, argillaceous saprolite, ferruginous saprolite and lateritic overburden. The thickness of each horizon varies from one deposit to another, the whole profile generally exceeding 20 m. The saprolitic horizons with inherited minerals (serpentine, chlorite) or neoformed minerals (smectites) constitute the silicated nickel ore and are thicker were climatic conditions are drier; the ferruginous upper horizons made up of iron oxide-hydroxides are more developed in more humid regions. In Brazil, the silicated ore generally prevails over the oxidized ore. The main Ni-bearing minerals are serpentine, smectite, garnierite and goethite. The lateritic nickel deposits of Brazil may be correlated with two erosion surfaces, corresponding to the Sul Americano (Lower Tertiary) and Velhas (Upper Tertiary) levelling cycles. The degree of dismantling of the higher and more ancient surface and the consequent development of the Velhas Surface control the position of the nickel accumulation in the landscape. Thus, the deposits may be found either in the lowlands or in the highlands, where they are always covered by a silcrete layer. The alteration profiles in the Brazilian lateritic nickel deposits are broadly similar to those described elsewhere in the world. However, they present two characteristic features: the silicated ore prevails over the oxidized ore, and a silicified layer covers the profies developed on the highlands.     

Specification and prediction of nickel mobilization using artificial intelligence methods

Groundwater and soil pollution from pyrite oxidation, acid mine drainage generation, and release and transport of toxic metals are common environmental problems associated with the mining industry. Nickel is one toxic metal considered to be a key pollutant in some mining setting; to date, its formation mechanism has not yet been fully evaluated. The goals of this study are 1) to describe the process of nickel mobilization in waste dumps by introducing a novel conceptual model, and 2) to predict nickel concentration using two algorithms, namely the support vector machine (SVM) and the general regression neural network (GRNN). The results obtained from this study have shown that considerable amount of nickel concentration can be arrived into the water flow system during the oxidation of pyrite and subsequent Acid Drainage (AMD) generation. It was concluded that pyrite, water, and oxygen are the most important factors for nickel pollution generation while pH condition, SO₄, HCO₃, TDS, EC, Mg, Fe, Zn, and Cu are measured quantities playing significant role in nickel mobilization. SVM and GRNN have predicted nickel concentration with a high degree of accuracy. Hence, SVM and GRNN can be considered as appropriate tools for environmental risk assessment.     

深海底质土-金属界面间黏附特性试验研究

基于取样于太平洋C-C矿区(Clarion-Clipperton Zone)的深海底质土,采用美国INSTRON公司生产的5943型万能材料试验机,选用4种常用的海洋金属,自制金属模具,开展黏附特性试验,研究孔隙比、法向压力和加载速度等因素对深海底质土与金属界面间黏附特性的影响规律。并基于平行圆盘分离力的计算公式,建立了深海底质土-金属界面表层土黏附指数的计算公式。研究结果表明：随着土样孔隙比的增加,黏附力呈增加的趋势,增速先快后慢,最终趋于平缓。随着法向压力的增加,深海底质土与金属界面间的表层土黏附指数呈指数函数增加趋势。随着加载速度的增加,深海底质土与金属界面间的表层土黏附指数反而呈逐渐减小的趋势。4种金属中,铝合金5052和钛合金STi80对深海底质土表层土的黏附能力较弱。该研究结果为我国深海采矿系统的安全运行提供一定的理论依据。     

Accumulation and ecological effects of soil heavy metals in conventional and organic greenhouse vegetable production systems in Nanjing,China

The spatial variability of soil heavy metals in conventional and organic greenhouse vegetable production (CGVP and OGVP) systems can reveal the influence of different farming activities on their accumulation and plant uptake. This provides important basic data for soil utilization and pollution risk assessment. Based on horizontal and vertical spatial analysis, this paper presents the spatial variability and accumulation of soil heavy metals. The effects on plant uptake and factors influencing heavy metal accumulation are presented using the two typical greenhouse vegetable sites in Nanjing City, China as examples. Results showed that different greenhouse vegetable production systems had their own dominant heavy metal accumulation, specifically, Hg and Pb in CGVP system and Cd in OGVP system. The spatial analysis showed that horizontally, distribution of soil properties and heavy metal concentrations in the two sites showed decreases from specific regions to the periphery for organic matter (OM), Cd, Cu, Hg, Pb, and Zn in CGVP and OM, As, Cd, Cu, Hg, Pb, and Zn in OGVP. Vertically, soil properties and heavy metals mainly vary in the topsoil. The key factor for the accumulation was excess fertilizer input. Variation of soil properties and the accumulation of soil heavy metals significantly influenced heavy metal uptake by plants. However, accumulation risk varied according to different heavy metals and different plant species. Environmental management of these two kinds of production systems should pay more attention to fertilizer application, plant selection, and soil properties.     

土壤地球化学测量在菲律宾红土型镍矿勘查中的应用

通过在菲律宾迪纳加特岛红土型镍矿勘查区开展土壤地球化学测量工作,发现了一批有价值的地球化学异常。根据红土型镍矿的成矿地质条件与特征,评价了异常区的找矿潜力,圈定了红土型镍矿的找矿靶区,并在靶区的工程查证中取得了较好的找矿效果。工作效果证明,土壤地球化学测量方法对于红土型镍矿的找矿具有高效、快速和低成本的优势。     

河北阜平县表层土壤重金属对人体健康的风险评估

河北省阜平县矿产资源丰富,矿产开发会产生大量重金属污染物,近年来大力发展果农业,也会对表层土壤造成一定影响,目前该县表层土壤重金属现状尚不清晰.为评估阜平县农业重点区表层土壤重金属污染特征和对人体健康的影响,本文按照1:5万土地质量调查规范要求,布设标准网格在该县农业重点区采集表层土壤样品647组,采用原子荧光光谱、电...     

Discrimination of lithogenic and anthropogenic sources of metals and sulphur in soils of the central-northern part of the Zambian Copperbelt Mining District: A topsoil vs. subsurface soil concept

Samples of topsoil together with reference samples of subsurface soil from a depth of 80–90 cm were collected in the central-northern part of the Zambian Copperbelt to distinguish lithogenic sources of metals from anthropogenic contamination of soils caused by fallout of dust from mining operations, flotation ore treatment plants, tailings dams, smelters and slag dumping grounds. The total sulphur, Cu and Co contents were found to be significantly higher in topsoil relative to subsurface soil over a large part of the surveyed area, and Zn, Pb, As and Hg contents showed a definite increase in the close neighbourhood of smelters and in the direction of prevailing winds. This indicates that the increase of these elements in the topsoil is due to anthropogenic activities. The areal extent and degree of anthropogenic contamination of topsoil can be expressed by an enrichment index (EI) based on the average ratio of the actual and median concentrations of the given contaminants. Although the contamination of soil by dust fallout decreases progressively with depth in the soil profile, in areas strongly affected by mining and mineral processing the anthropogenic contamination by sulphur and copper can be traced to a depth of 80–90 cm. In contrast, the concentration of elements such as Cr, Ni, and V, that show a direct correlation with the content of iron in the soils, increases in the subsurface soil relative to the topsoil. This is particularly evident in areas underlain by rocks of the Katanga Supergroup.     

Al speciation in tropical podzols of the upper Amazon Basin: A solid-state Al MAS and MQMAS NMR study

In the upper Amazon Basin, aluminum previously accumulated in lateritic formations is massively remobilised in soils by podzolization and exported in waters. We have investigated the speciation of aluminum in the clay-size fractions of eight horizons of waterlogged podzols lying in a depression of a plateau. The horizons illustrate the main steps involved in the podzolization of laterites. They belong to eluviated topsoil A horizons and illuviated subsoil Bhs, Bh and 2BCs horizons of weakly and better-expressed podzols located at the margin and centre of the depression. For the first time, aluminum speciation is quantitatively assessed in soils by spectroscopic methods, namely FTIR, ²⁷Al magic angle spinning (MAS) and multiple-quantum magic angle spinning (MQMAS), nuclear magnetic resonance (NMR). The results thus obtained are compared to chemical extraction data.Solid-state ²⁷Al MAS NMR spectra enable to distinguish Al bound to organic compounds from that incorporated in secondary mineral phases detected by FTIR. MQMAS experiments additionally show that both chemical shifts and quadrupolar constants are distributed for Al nuclei linked with organic compounds. Similar amounts of chelated Al are obtained from NMR spectra and chemical extractions. The study enables to highlight three major steps in the fate of aluminum. (i) Aluminum is first released by mineral weathering, feeds complexing sites of organic matter and accumulates in subsurface Bhs horizons of weakly expressed podzols (acidocomplexolysis). (ii) Complexes of aluminum with organic matter (Al-OM) then migrate downwards in sandy horizons of better-expressed podzols and accumulate at depth in less permeable 2BCs horizons. (iii) The minor amounts of aluminum present in the 2BCs horizon of the downslope podzol show that aluminum is eventually exported towards the river network, either complexed with organic matter or as Al³⁺ ions after desorption from organic compounds, due to decreasing pH or biodegradation of organic ligands. The direct spectroscopic determination of Al-speciation during the formation of podzolic soils opens new perspectives to trace metal loads in the rivers of the upper Amazon Basin.     

广东大宝山矿区横石河沿岸水土重金属分布规律及其累积风险

研究矿业活动重金属的释放、迁移及累积特征对于控制和治理矿区水土环境污染具有重要的意义。本文通过广东大宝山矿区水土污染源调查及横石河流域沿岸水土样品采集,以研究区土壤对照值及国家环境质量为标准,试图探讨了大宝山矿区重金属迁移及累积特征。研究结果表明,横石河沿岸土壤重金属元素主要来自采矿活动的酸性废水的排放,土壤中Cd、Pb、Cu和Zn的含量均超过对照值,呈现出明显的累积特征,且Cd、Cu含量超过了国家土壤环境质量标准;土壤中重金属累积程度及其风险等级呈现出从源头向下游递减的特点,其中凉桥、水楼下地段农田重金属处于高风险区,阳河-莲心村虽有累积,但无风险;上坝村地处土壤重金属累积的中风险区,下坝村处于低风险区。研究结果为矿区重金属污染防治提供了重要依据。     

江苏省土壤重金属分布特征与污染源初步研究

以24 186个表层土壤(0～20 cm)和6 127个深层土壤(150～200 cm)样品之Cd、Hg、Pb、As等含量数据为基础,研究了江苏全省土壤环境的重金属分布与主要污染特征.结果表明.全省自然土壤环境与人为活动土壤环境的重金属元素分布都不均匀,但人为活动土壤环境中的不均衡程度远高于自然土壤环境:全省农田中有1.02%的土壤受到Cd、Hg、Pb等8种重金属的严重污染,苏州市、无锡市土壤环境被重金属污染的程度相对严重;工业化、城市化进程中的人为活动及自然地质作用都是引起江苏局部土壤重金属污染的重要原因,自然成因的重金属污染土壤多呈面状、多元素、低强度、双层污染等特点,从而与人为成因的重金属污染土壤有所区别.     

凹凸棒石用于修复铜锌镉重金属污染土壤的研究

利用凹凸棒石黏土矿物优异的物化性能对采集的安徽铜陵地区重金属污染土壤进行盆栽修复试验,以降低种植蔬菜中重金属污染物的有效态含量。凹凸棒石与矿区土壤的质量配比设置5组(1∶10、1∶20、1∶40、1∶100以及原土),选择适宜在北京生长的四季小白菜和北京快菜进行种植,盆栽试验结果表明,使用凹凸棒石黏土矿物可以将土壤的pH值提高到5～8,改善了矿区的土壤环境条件,提高黏土矿物对重金属的吸附性能;通过适量添加凹凸棒石黏土矿物,对Cu元素的平均修复率达到31.50%,Zn元素的平均修复率达到26.15%,Cd元素的平均修复率达到34.92%,能够有效减少蔬菜对Cu、Zn、Cd三种重金属元素的吸收。凹凸棒石与土壤的质量比为1∶20时,对污染土壤的修复效果最佳。     

内蒙古废弃钨钼矿区周围土壤重金属污染生态环境评价及成因分析

为研究内蒙古赤峰市废弃钨钼矿区周围土壤重金属污染特征、潜在生态风险及成因分析，共采集83份表层土壤样品和6个土壤钻孔。采用ArcGIS空间插值分析方法研究As、Cd、Cr、Cu、Ni、Pb、Mo和Zn的空间分布，构建重金属扰动指数函数研究重金属受人类活动的污染程度，利用地累积指数法验证矿区周围土壤重金属污染程度，通过相关性分析判断重金属来源并讨论污染成因。结果表明：矿区周围土壤As、Cd、Cu、Pb、Zn和Mo平均含量明显高于矿区周边背景值，高含量主要分布尾矿库周围，主要来源为矿山采选活动；Cr和Ni基本无污染，主要来源为母岩风化。通过重金属扰动指数函数计算发现：采用区域背景值对矿区周围进行重金属污染评价夸大了矿山采选活动对矿区周围土壤重金属的污染，矿区周围土壤重金属污染是由于天然重金属富集和采矿活动共同作用下的“双驱动模式”导致，尾矿库周围土壤重金属污染程度随着与尾矿库水平距离的增加和深度的加大而逐渐降低。降水量丰富程度是影响重金属迁移能力的关键因素，该矿处于降水量匮乏地区，尾矿库对周围土壤重金属污染范围有限，对生态环境影响轻微。     

河套平原表层土壤元素含量与空间分布特征

文中分析了河套平原不同表层土壤的元素含量,并运用统计学方法探讨了河套平原表层土壤元素的组成和空间变化。结果表明:河套地区土壤Al、Fe等元素与Na、Sr化学活动性元素的特征差异较大;而重金属元素Cu、Mn、Pb、Zn等元素存在异常,变异系数较大,明显受人类活动的影响,可作为人类工业活动的指标。表层土壤元素的空间变异特征表明,Ca、Mg等稳定元素存在明显的空间相关性,反映了土壤母质对元素含量影响较大;P元素的理论模型为线性,与河套地区大面积农田使用磷肥过量有关;重金属元素为中等强度的空间相关性,表明受到工农业生产等小尺度因素的影响。河套平原地区重金属元素空间分布总体呈现北部和南部地区较高,且北高南低,东西向变化不明显的特征,这与当地的工业开矿、城市化发展以及工农业的生产等人类活动密切相关。     

重金属铅、铬在土壤中的迁移特征——以泉州市为例

泉州市地处福建省东南部,工农业均比较发达。随着经济的发展,工矿企业遗留下来的污染问题也愈发突出。选择重金属Pb和Cr为研究对象,通过土柱实验和Hydrus-1D软件模拟,研究其在红壤和风沙土中的迁移特征。结果表明:重金属Cr在土壤剖面中的迁移速率和迁移量变化明显,尤其是风沙土,重金属Cr可以在两个月左右迁移至土壤剖面底部(80cm土层厚度)进入地下含水层;而重金属Pb在土壤剖面中的迁移速率很慢,迁移量也不大,污染源产生的污染物绝大多数在研究期内均被表层土壤吸附。因此在场地污染调查、评价和修复时,重金属Pb主要应该针对污染场地表层土壤层,而重金属Cr主要应考虑地下水,尤其是风沙土区域的地下水,且应于污染初期进行污染控制。     

煤矸石堆周围土壤重金属污染特征分析--以焦作市中马村矿为例

利用扇形布点法采集了焦作市中马村矿矸石堆周围土壤，对其中的Cr、Pb、Cu、Mn4种重金属含量进行了研究。结果表明：煤矸石的堆放对周围土壤造成不同程度的污染，重金属的含量随离矸石堆距离增大呈减小的趋势，主要受到风向的影响。     

The role in lateritic nickel mining in Latin American countries with special reference to exmibal in Guatemala

Modern mining operations can result in significant economic development within the developing host countries. Lateritic nickel mining plays a role of varying importance in a number of Latin American countries, depending on natural resource endowments and government policies. Exploraciones y Explotaciones Mineras Izabal, SA (Exmibal) is a large-scale lateritic nickel mining operation that serves as an excellent case study in the analysis of mining-induced economic development at local, regional and national scales. Exmibal's turbulent history demonstrates the need to view mining dynamically and in the context of production and consumption restraints. Guatemala's experience will Exmibal may be generalized most successfully to other Latin American countries that have or may have one large nickel mining complex operated by a transnational enterprise.     

武水河上游区域土壤重金属污染风险及来源分析

生态功能区在涵养水源、保持水土、维系生物多样性等方面具有重要的作用。本文以位于南岭生态功能区的流域——武水流域为研究对象,采集流域上游交通运输用地、采矿用地、工业用地、耕地及林地5种土地利用类型土壤样品,分析7种重金属Cd、As、Cu、Hg、Ni、Pb、Zn的含量特征,采用内梅罗综合污染指数评价重金属污染的程度,Hakanson潜在生态风险指数法评价土壤重金属潜在生态风险,并应用主成分分析法探究重金属污染的来源。研究结果显示,武水河上游地区土壤重金属Cd、As、Cu、Hg、Ni、Pb、Zn平均含量分别为1.28、72.44、54.62、0.27、68.32、72.29和158.42mg/kg,均高于土壤背景值,其中采矿用地土壤重金含量除Hg外均高于其他类型土壤。均值状态下土壤中Cd和As单因子污染指数分别为5.07、3.25,其中采矿用地中Cd单因子污染指数可达13.59;土壤重金属综合污染指数表明,采矿用地污染最为严重,其次是工业用地,林地呈安全状态。潜在生态危害指数评价结果显示,采矿用地和工业用地达到了强生态危害,其他类型土壤为轻微生态危害,而采矿用地土壤中Cd达到极强生态危害,As为强生态危害。土壤重金属来源研究结果表明,As、Cd、Cu和Zn来源于矿山开采及工业活动,Ni和Hg主要来源于成土母质,Pb则来源于交通运输。研究认为:武水流域上游区土壤重金属污染情况较为严重,Cd和As是区内主要的风险因子,主要来源于矿山开采以及工业活动。