Mine-water chemistry: the good, the bad and the ugly

 Contaminative mine drainage waters have become one of the major hydrogeological and geochemical problems arising from mankind's intrusion into the geosphere. Mine drainage waters in Scandinavia and the United Kingdom are of three main types: (1) saline formation waters; (2) acidic, heavy-metal-containing, sulphate waters derived from pyrite oxidation, and (3) alkaline, hydrogen-sulphide-containing, heavy-metal-poor waters resulting from buffering reactions and/or sulphate reduction. Mine waters are not merely to be perceived as problems, they can be regarded as industrial or drinking water sources and have been used for sewage treatment, tanning and industrial metals extraction. Mine-water problems may be addressed by isolating the contaminant source, by suppressing the reactions releasing contaminants, or by active or passive water treatment. Innovative treatment techniques such as galvanic suppression, application of bactericides, neutralising or reducing agents (pulverised fly ash-based grouts, cattle manure, whey, brewers' yeast) require further research. Received: 13 August 1996 · Accepted: 3 January 1997     

Jarosite-related chemical processes and water ecotoxicity in simplified anaerobic microcosm wetlands

Simulation experiments were conducted to examine whether jarosite is decomposed and toxic products are produced under anaerobic microcosm wetland conditions. The results show that jarosite was stable under water inundation in the microcosm wetland for a period of at least 56 days when no organic substance was added. However, jarosite became increasingly unstable with increasing amount of added organic matter. This resulted in entry of ferrous Fe into the soil solutions. Concentration of other heavy metals in the leachates was extremely low except for Mn. This is attributed to the maintenance of a high pH in the microcosm wetlands, which might cause re-precipitation of originally jarosite-borne heavy metals, if any. No acute toxicity was observed for leachate from the control (non organic matter-added treatment). However, leachates from various organic matter-added treatments show varying degrees of toxicity to the test organism and soluble Fe was likely to be the dominant metal of potential toxicity. Atmospheric exposure of leachate led to oxidation of ferrous Fe and precipitation of iron hydroxide, which caused a drop in leachate pH. This, in turn, inhibited further oxidation of ferrous Fe.     

不同天气系统宁夏夏季降雨谱分布参量特征的观测研究

利用 1982— 1984年 6～ 9月份在 7个气象站 2 0 0次观测获取的 6 0 5 3份滴谱资料 ,分析了宁夏雨滴谱及有关物理量的特征。宁夏地区夏季降水平均雨滴空间浓度数为 2 85个·m-3 ,平均谱可以描述为N(Di) =2 0 9.2exp(- 2 .6 335Di)。文中给出了不同雨强下的平均谱分布及谱参数的演变和影响降水的 3种环流形势下的平均滴谱特征 ,还分别建立了雷达反射率因子Z与雨强、雨滴落地动能通量和雨水含量之间的相关关系。这些资料可用于雷达定量测定降水和区域降水量、水土保持和生态环境建设     

我国酸沉降地区硫源的硫同位素组成研究

我国同世界大部分地区的酸雨类型一致,均为典型的硫酸型酸雨,因此硫同位素组成是示踪酸雨来源的重要手段。在前人研究的基础上,对酸雨硫同位素组成研究的思路和实验方法进行综述,重点介绍燃煤过程中硫同位素的分馏效应和大气SO2、气溶胶、大气降水、苔藓和小麦等植物中的硫同位素组成等,对环境地球化学的研究具有重要意义。     

Late Proterozoic Acid Magmatism and Associated Tungsten Mineralisation in Northwest India

The crustal evolution of northwestern India is marked by several episodes of acid magmatism during Late Proterozoic period (900-700 Ma). These events occurred during the culmination of Delhi orogenic cycle and continued till the emergence of a stable Aravalli craton. Some of these granites emplaced within the Delhi Supergroup of rocks in central and southern parts of Rajasthan are associated with tungsten mineralisation. This includes three important tungsten deposits, namely those of Degana, Sirohi and Sewariya areas. The geological setting, petrography and geochemical characteristics of the mineralised granites in these deposits are comparable while these features are quite different in non-mineralised granites of this region.Comparison of mineralised granites in the three areas indicates that: (1) these are relatively small plutons, (2) they are emplaced at high crustal level, (3) the roof of the pluton is either just exposed or lies closely beneath ground surface, and (4) the granites are geochemically specialised with enrichment of alumina, W, B, F, Rb and Li, and depletion of Sr.     

松辽高平原地下水年龄：公主岭附近同位素水文地质剖面研究

本文运用稳定同位素δD、δ~(13)O阐述了公主岭一带地下水成因,并根据水文地质条件和稳定同位素混合模型,采用放射性同位素~3H、~(14)C计算出地下水在含水层中平均滞留年龄。通过分析,对天然状态下和长期开采条件下地下水循环周期也提出了新认识。因此,公主岭一带地下水同位素年龄的研究,对山前高平原各城镇开辟供水水源地具有重要的生产实践意义。     

Holocene ochreous lacustrine sediments within the Famatina Belt,NW Argentina: A natural case for fossil damming of an acid drainage system

A 44 m-thick lacustrine succession of silty-clay banded ochres and subordinated sandstones, and conglomerates (known as the Corral Amarillo Formation) is superbly exposed within the Famatina Belt (Central Andes of Argentina) after deep entrenchment by the present-day Amarillo river due to strong recent uplifting and consequent relative drop in base level. The unusual ochreous-rich succession was produced by natural damming (3.48–3.54 ¹⁴C kyr BP) of an acid drainage system linked to the alteration cap of polymetallic deposits. Facies of silty-clay ochre (wet season) and banded ochre (dry season) from the paleolacustrine setting are composed of jarosite + goethite and goethite respectively. Geochemically, these layers record high concentrations of Fe₂O₃ (25–55 wt. %) and trace elements (Cu, Zn, Co, As, and Mo with mean concentrations of 2759; 2467; 109; 375 and 116 ppm, respectively). Their origin is inferred from a comparative analysis with the present-day Amarillo river, which has a pH of ∼3, (SO₄)²⁻ concentrations of ∼5000 mg/l, and jarosite as the dominant phase, in the upper catchments. Waters downstream have pH values of 3–4.5, (SO₄)²⁻ concentrations of ∼3000–480 mg/l, and schwertmannite as the dominant phase. Thus goethite in the paleolake facies is likely related to schwertmannite transformation by an aging process, whereas jarosite is probably transported from the river but could also be associated with post-depositional formation regulated by variations in grain size and the pore fluid chemistry. The Corral Amarillo Formation offers a Natural model, which may be employed to infer the effect on nature of acid drainage of mineralized areas.     

Mobility and retention of trace elements in hardpan-cemented cassiterite tailings, north Queensland, Australia

This study reports on the mobility and retention of trace elements in cassiterite tailings at the inactive Jumna mill, tropical north Queensland. Since the 1980s, the uncapped tailings have developed laterally discontinuous Fe-rich hardpans, which are located in the higher parts of gently sloping tailings masses and at the top (<50 cm) of the tailings piles. Hardpan-cemented tailings comprise thin layers (typically ∼0.2–2 mm thick) of HFO (hydrous ferric oxides) and sulfate efflorescences cementing tailings grains. In comparison to the tailings, the hardpan-cemented tailings contain significantly higher median As, Ca, Cd, Co, Cu, Fe, In, Mn, Mo, S_total, Th, U, Y and Zn values. Partial leaching studies of tailings and pond water analyses indicate that wetting and acidification of Fe-cemented tailings removes significant proportions of trace elements into pore and surface waters. Tin shows no mobility due to the presence of weathering-resistant cassiterite (SnO₂) and, As and Pb display limited mobility possibly due to their coprecipitation with jarosite-type phases and HFO materials at the top of the tailings profile. By contrast, the trace elements Cd, Ce, Cu, La, Ni, Pb, U and Zn display the greatest mobility, possibly due to their incorporation in soluble sulfate efflorescences and sorption onto mineral and HFO surfaces. Hence, the Fe-rich hardpans do not protect the sulfidic tailings from further oxidation nor do they cause permanent sequestration of trace elements.     

An evaluation of acid deposition on cation leaching and weathering rates of an Andosol and a Cambisol

An evaluation of the response of an Andosol and a Cambisol to acid deposition and weathering rates was studied by using a controlled laboratory leaching experiment. Both soils where derived from mafic parent material, a Histic Andosol from Western Iceland and a Cambisol from North East Scotland. De-ionized water and water acidified with H₂SO₄ (pH 3) was leached through reconstructed soil columns to simulate 34 years of precipitation.Acidic input increased cation leaching and weathering rates in both soil types and reduced pH levels. The Andosol proved generally to have higher weathering rates, leaching potential, ion exchange and acid-buffering capacity as well as maintaining a relatively steady pH despite intense acidic input. This was due to differences in parent material and mineral composition. The Andosol was developed from basaltic volcanic tephra, which had higher dissolution rates due to its amorphous mineral structures. The Cambisol was developed from gabbro with more stable mineral structures.