The Hydrogeochemistry of Arsenic in the Clara Mine,Germany

Abstract.   The oxidative dissolution of primary arsenic-bearing sulfide minerals in barite-fluorite veins is a potential source of arsenic in the Clara Mine. Geological structures, especially the mineral veins, provide potential pathways for the water. The highest arsenic concentrations are found in ground water within the eastern part of the mine. Arsenic and major ions are positively correlated and provide evidence that arsenic is likely derived locally from the water-vein/water-rock interaction. Geochemical modeling with PHREEQC shows all the arsenate mineral phases to be significantly undersaturated, although secondary arsenate minerals are common in the oxidized part of the deposit. The mine waters plot near the boundary of Fe(OH)₃ and Fe²⁺ in the pH-Eh diagram for the As-Fe-S-H₂O-system. Arsenic occurs as the 5-valent species and . Statistical analysis illustrates a strong association between As, Fe, pH, and HCO₃. Oxidation of the primary As-bearing minerals, such as pyrite and arsenopyrite, and the subsequent behavior of the oxyanion, arsenate, generally controls the distribution and speciation of arsenic. The low concentrations of dissolved As is due to co-precipitation and adsorption of arsenate by Fe, Al, and Mn (oxy)hydroxides.     

地下热水的水化学资料在判断断层中的应用——以聊城市城区地热田为例

聊城市城区西部临清拗陷区地下热水在水平方向上的水文地球化学特征具有明显的块段性,大致可分为F2断裂以东和F2断裂以西两个块段,这两个块段地下热水在主要离子组分、微量元素和特征系数等方面均有一定差异。本文根据地下热水水化学资料,判断出了F2断裂的大致位置,同时从地下热水水化学特征的块段性差异和地下热水的变质程度两个方面说明了F2断裂的判断依据。     

赣江河水主离子化学特征和径流效应以及控制机制

赣江发源于我国中南部的江西省,是长江的一大支流,为了客观分析该河流的水化学特征,开展水质评价,对赣江1958～2016年水化学数据进行了收集和分析。结果表明:①Ca~(2+),Na~++K~+,HCO_3~-和SO_4~(2-)是河流中的主要离子,pH值范围为6.0～8.8,TDS范围为15.7～141.0 mg/L,所有离子月变化量与河流流量呈正相关。1980年以前河流流量与SO_4~(2-),NO_3~-和Cl~-的浓度月变化正相关程度高于1980年以后,这表明河水化学特征1980年之前主要是非点源成因,但1980年以后为多种来源的混合。②海盐源Cl~-占河水Cl~-的比例小于19%,硫酸参与硅酸盐岩和碳酸盐岩的风化,反映了1980年以后人为活动有所加强。Cl~-/(Na~++Cl~-)和SO_4~(2-)/(Na~++Cl~-)的增加与江西省国内生产总量、人口、煤炭消耗、肥料用量的关系受废水排放影响。③根据世界卫生组织饮用水标准,赣江的水质符合饮用水标准,但应该警惕Cl~-和NO_3~-浓度在1980年后在持续增加。     

Geochemical modeling of groundwater in southern plain area of Pengyang County,Ningxia,China

The purpose of this paper iS to examine the evolution mechanisms of a hydrochemical field and to promote its benefits to the living standards of local people and to the Iocal economy in the southern plain area of Pengyang County,in Ningxia,China.Based on understanding of the hydrogeological conditions in PengYang County,the chemical evolution characteristies of groundwater in the plain area were analyzed.PHREEQC geochemical modeling software was used to perform hydrochemical modeling of water-rock interaction and to quantitatively analyze the evolution processes and the formation mechanisms of the local groundwater.Geochemical modeling was performed for two groundwater paths.The results showed that,along path 1,Na+ adsorption played the leading role in the precipitation process and its amount was the largest,up to 6.08 mmol/L;cation exchange was significant along path 1,while along simulated path 2,albite accounted for the largest amount of dissolution,reaching 9.06 mmol/L,and the cation exchange was not significant.According to the modeling results,along the groundwater flow path,calcite and dolomite showed oversaturated status with a precipitation trend.while the fluorite and gypsum throughout the simulated path were not saturated and showed a dissolution trend.The total dissolved solids(TDS)increased and water quality worsened along the flow path.The dissolution reactions of albite,CO2,and halite,the exchange adsorption reaction of Na+,and the precipitation of sodium montmorillonite and calcite were the primary hydrogeochemical reactions,resulting in changes of hydrochemical ingredients.     

基于水文地球化学的坝基帷幕防渗性能分析

充分考虑水溶液中络合物的影响,计算坝址库区水环境中方解石、白云石、石膏的饱和指数;结合化学热力学、化学动力学、水文地球化学、水文地质学和矿物溶解动力学理论基础,采用据此推导出的由水化学指标表示的达西定律解析式,计算水电站复合坝基帷幕地质体的渗透系数。将计算结果与现场压水试验和灌浆帷幕防渗控制值、幕后渗排水量、水压、析出现象等指标进行对比,分析该计算方法在帷幕地质体上的适用性及合理性,并据此分析评价水电站防渗帷幕的运行现状。结果表明,用水质指标计算的渗透系数能很好地说明灌浆帷幕地质体的渗透现状,对评价帷幕防渗性能有指示作用,可为其他类似工程的帷幕性能评价提供参考。     

北江大堤石角堤段渗漏探测分析

从北江大堤石角段的地质环境条件出发 ,根据同位素示踪和天然示踪 (包括水文地球化学条件 )的实际资料综合分析论证了石角段的基岩渗漏 ,认为石角段历年发生的渗透变形主要源于基岩集中渗漏通道 ,并通过连通试验证实。目前存在两条集中渗漏通道 ,并仍处于进一步的发展过程中。     

巴彦乌拉铀矿床酸法浸铀的水岩反应堵塞机理

为探讨酸法浸铀过程中含矿含水层的地球化学堵塞机理,运用PHREEQC模拟软件的化学形态和溶解度模拟,分析酸法浸泡试验中浸出液化学反应的化学组成成分,确定含矿含水层化学堵塞矿物的类型,得到含矿含水层发生化学堵塞的原因以及形成条件。根据模拟结果表明：巴彦乌拉地下铀矿中碳酸钙和针铁矿的含量相对较高,当高浓度的溶浸液注入地下含矿含水层之后,溶浸液会溶解碳酸钙和针铁矿,使Ca2+、Fe3+的浓度大幅度上升;当Ca2+、Fe3+浓度反应条件指数大于0时,Ca2+会与SO42-发生反应,生成石膏沉淀,而Fe3+会与阴离子发生反应,生成铁矿物沉淀,导致孔隙率下降,渗透性降低,注液压力增大,注液流量减小,抽液量降低,地浸效益下降。基于以上研究,可为后续实际铀矿床的堵塞和铀的浸出提供参考价值。     

策克口岸水文地球化学特征分析

在充分理解额济纳旗策克地区水文地质条件的基础上,先进行水化学的数理统计分析,进而选取水文地质剖面即初始和终了水样点,结合水样的水化学的数理统计分析结果和水文地质条件确定地下水矿物相并计算剖面上矿物相进入或离开地下水的量,探明区域水文地球化学演变规律,为该区的生态环境保护和合理利用水资源提供科学的依据。     

Hydrogeological characteristics of a groundwater-dependent ecosystem (La Lantejuela, Spain)

By means of a simple water balance model, together with hydrogeochemical and morphological interpretation, the hydrogeological characteristics of a series of playa lakes forming an endorheic complex within the Guadalquivir river basin in Southern Spain (La Lantejuela) have been evaluated. The lakes are demonstrated to be groundwater-dependent ecosystems. The main source of groundwater input to the lakes is from an unconfined detritic aquifer, the playa lakes being the natural discharge points from the aquifer within the endorheic complex. High rates of evaporation from the lakes induce a centripetal groundwater flow pattern. This water body has been disturbed by a combination of extensive drainage works and intensive groundwater abstraction. There is a need for a sustainable water management strategy for the whole catchment area. It is hoped this will be an issue addressed within the Guadalquivir river basin management plan in accordance with the requirements of the European Water Framework Directive (WFD).     

地下水主要离子水文地球化学过程与矿井突水水源识别

选取10种化学组分利用多元统计分析确定龙门峡南煤矿矿区范围内水化学过程,并进行了风井突水点水源识别。研究区内地下水属于HCO3-Ca型水。选取三个特征根大于1的主成分进行分析表明,PC1表示方解石、白云石和石膏等矿物自然风化影响离子交换,PC2和PC3则分别表示区内水文过程、农业活动及蒸发作用的影响。研究表明,天然矿物的自然风化和离子交换是其中最重要的影响因素。根据Q型聚类分析将水样划分为4个集群(Group1至Group4),通过对枯、丰两个时期内水样进行对比,确定水样间的相似关系,判断风井涌水水样M1、M2与泉点水样S3具有极大的相似性。