Water supplies from chalk aquifers in northern Europe can be contaminated by semi-metals such as As and metals such as Cr, Ni and many more, as a result of leaks from landfills, industrial sites and from natural oxidation of pyrite in the chalk, releasing trace elements. Chalk, which is predominantly calcite (CaCO3), has the ability to immobilize Ni, but its uptake by chalk is sometimes greater than expected. In an attempt to identify the controls on metal uptake, chalk samples from Klintholm I/S (Fyn, Denmark) were decalcified in EDTA solution and the residue was examined with transmission electron microscopy (TEM) for morphology and composition. Energy dispersive X-ray spectrometry (EDXS) revealed minor Si and Al (probably clay) and major Mn and Fe as (hydr)oxides. These natural nanoparticles have very large surface areas contributing to chalk’s uptake capacity for Ni and other metals from groundwater.

Nickel can cause allergic reactions so it is often considered to be a toxic metal. In some areas of Denmark and northern Europe, where drinking water comes predominantly from chalk aquifers, Ni concentrations in groundwater are higher than safety limits. The contamination is natural in the sense that it comes from oxidation of small grains of pyrite in the chalk that contain Ni as a trace element (Larsen and Postma, 1997). Because of Danish water-treatment practice, the most politically acceptable water-supply protocol is not to use secondary water treatment, so in order to minimize allergy risks for consumers, high-Ni water is either mixed with low-Ni water to bring concentrations below the Danish limit, or new, uncontaminated wells are drilled. Some recent efforts focused on finding a method to minimize nickel concentration while the water is still in the ground, before it is pumped to the primary treatment facility and distributed.

Unfortunately, only a few experimental studies of the interactions between Ni and calcite have been published (Lakshtanov and Stipp, 2007; Zachara et al., 1991; Hoffmann and Stipp, 2001) and we found no previous work on Ni uptake by chalk. Experiments with calcite show that Ni forms surface complexes and it is incorporated into the solid as solid solution. Chalk aquifers often contain as much as 99% calcite, so the same processes ought to control Ni uptake, but some very preliminary experiments suggested that chalk behaviour might not be what one would expect by analogy with calcite (Stipp et al., 2005). The aim of this study was to examine the Ni-uptake capacity of chalk and compare it with that of synthetic, pure calcite.

Uranium is a redox-sensitive element and can be immobilized by reduction from soluble U(VI) to insoluble U(IV). By performing flow-through experiments, uranium mobility was observed under different redox conditions. Inflow solutions with different electron acceptors, nitrate and sulphate, and a control inflow solution were used to obtain different sedimentary redox conditions. Uranium was about one order more mobile when nitrate was used than when sulphate or the control was used. The difference in uranium mobility is attributed to the reduction of uranium. Even though uranium mobility is heavily dependent on the redox state of uranium, sedimentary concentrations of organic matter argue that organic matter is the most important complexing agent and that this determines the retardation of uranium.

In this paper, the kinetics of Mo and V (100 μM) uptake on ferrihydrite (FHY) were evaluated in batch, mono-sorbate systems at pH between 4 and 9, and in bi-sorbate systems in the presence of P (100 μM) at pH 7. In the Mo and V single-sorbate experiments, 100% adsorption was observed at pH values below 6 and 8, respectively. Above the point of zero charge (PZC = 7.97) of FHY, the adsorption efficiency for Mo dropped dramatically (20% at pH 8) while V showed high uptake efficiencies even at pH 9 (60% efficiency). The results from the bi-sorbate experiments (Mo-P and V-P) showed that at pH 7, P out-competed (97%) Mo for binding sites on FHY, while in the V-P binary system only ∼44% of the binding sites are occupied by P with the remaining sites being occupied by V.

Experimental geochemical studies have shown the effectiveness of Cd removal from freshwaters by sorption onto calcite and aragonite. The strong affinity of Cd for these minerals suggests that a similar inorganic uptake could take place in the oceans. In this study, we have carried out sorption experiments by reacting calcite particles with Cd-enriched artificial seawater. Cadmium concentrations in solution were determined by ICP-AES. Salinity-normalized Cd concentrations showed an average net decrease of 30%. Depending on several factors, this inorganic uptake could influence the seawater concentrations of Cd in certain locations, and even contribute to a natural regulation of the concentration of this metal in the oceans.

Landfill and radioactive waste disposal risk assessments focus on contaminant transport and are principally concerned with understanding the movement of gas, water and solutes through engineered barriers and naturalgroundwater systems. However, microbiologicalactivity can impact on transport processes changing the chemicaland physicalcharacteristics of the subsurface environment. Such effects are generally caused by biofilms attached to rock surfaces. This paper will present some mineralogical and petrographical observations of materials extracted at the completion of an experimental column study which examined the influences of biofilm growth on groundwater flow through crushed diorite from the Äspö Hard Rock Underground Research Laboratory, Sweden.

In December, 2007, after 30 years of operations, the mine of Meirama ceased extraction of brown lignite. Since then operations have begun which will lead to the formation of a big mining lake (~2 km2 surface and up to 180 m deep) after controlled flooding of the open pit. In the process of flooding, both surface and ground waters are involved, each with their own chemical signature. According to the information available, the diversion of surface waters towards the pit hole should lead to the formation of a water body of acceptable quality. However, an unassisted flooding process could eventually form an acidic lake.

Semi-aquatic and native plants collected from a mining site in the Iberian Pyrite Belt were analysed. Semi-aquatic plants showed enrichment of Cu (1.2—11 times), Zn (1.3—6 times), Pb (5—8 times) and As (24—1300 times) relative to typical concentrations in plants of the same species growing at uncontaminated sites. Translocation factors indicate limited internal metal transportation from roots to shoots. Infrared spectroscopy identified aromatic and aliphatic C-H (CH2) groups, S-O complexes and kaolinite in semi-aquatic plants.

Lake sediments were studied from four lakes in environmentally different areas in northern Finland. Lakes Pyykösjärvi and Kuivasjärvi are situated near roads with heavy traffic and the city of Oulu. Lakes Martinlampi and Umpilampi are small lakes in a forest area with no immediate human impact nearby. The concentration of Pb increases in the upper parts of the sedimentary columns of Lake Kuivasjärvi and Lake Pyykösjärvi. This is interpreted as being an anthropogenic effect related to heavy traffic in the area and use of Lake Pyykösjärvi as an airport during World War II. High Ni and Zn concentrations in the Lake Umpilampi sediments are caused by weathered black schists. Sediments in Lake Martinlampi show high Pb and Zn contents with increasing Pb concentrations up through the sedimentary column. The sources of these elements are probably Pb-Zn mineralization in the bedrock, Pb-Zn-rich boulders and anomalous Pb and Zn contents in till in the catchment area of the lake.

White and yellowish precipitates were found in a gravel pit in the Kumpuselkäesker chain during the summers of 2004—2007. The esker is located in northern Finland, in the northern Ostrobothnia schist area which contains mica schists with quartz veins, which are locally enriched in Co, Cu, Au, Zn, Pb and Ni. A thin till bed lies between the esker gravel and bedrock. Precipitates were found as small grains on the till surface, encrusting twigs and around small pebbles. Ground-water ponds in the pit measured in the summer of 2006 were very acidic as was the till material. The precipitates comprise secondary sulphates, such as gypsum, pickeringite and Mg-sulphates, which are all water-soluble.

Atomic force microscopy (AFM) has been used to monitor the appearance and behaviour of the hormone progesterone on mineral surfaces, including mica and highly oriented pyrolytic graphite (HOPG). Different solvents have been used resulting in various features on the two substrates. After the application of 254 nm ultra-violet (UV) light, changes in structure of the adsorbed hormone have been observed. To understand the reactions at the progesterone-mica interface in aqueous solution, adsorption has been studied in situ with AFM.

Spring and stream waters from the San Antonio de los Cobres area in NW Argentina have high concentrations of arsenic (As) (151—9490 μg l-1), of which AsV varies widely (6—~100% of total As). Arsenic concentrations correlate with Na, K, Cl, HCO3, B and Li, which are high in the spring waters and are typical of geothermal areas world-wide. Springs near San Antonio supply large amounts of As to the Rio San Antonio de los Cobres (up to 1180 μg l-1), but these concentrations decline to 400 μg l-1 within 10 km of the spring inputs, due to dilution and mineral precipitation.

Several field and laboratory studies have demonstrated that secondary Fe-bearing minerals such as goethite, lepidocrocite and mackinawite have a high capacity for the uptake of As, but little work has been carried out to examine the capacity of the mineral vivianite [Fe3(PO4)2·8H2O] for this element. We report here preliminary results of an experimental study designed to test the efficiency of As(III) and As(V) uptake by natural vivianite at acid, near-neutral and alkaline pH at T = 4ºC, which is representative of Lake Baikal-type environments, where natural vivianite is reported to occur. The vivianite takes up between 0 and 5% As(III), and between 21 and 45% As(V), from 200 ppb solutions of these As species. Further work at 25ºC and other solution concentrations, together with characterization of the post-sorption solids, will yield information on the efficiencies and mechanisms of As uptake by natural vivianite.

Considering an ideal solid solution, the partitioning of cadmium in calcite was studied at different levels of supersaturation (δ) using counter-diffusion experiments. The effective (non-equilibrium) distribution coefficients of Cd2+ in calcite (DCd), varied between 20 and 100 depending on the initial concentration of reactants and the evolution of supersaturation. A function that relates the DCd with the supersaturation at nucleation was derived: logDCd= —0.40logδ + 2.42. The relationship obtained suggests that in naturalwaters, Cd2+ can be incorporated to a greater degree in calcite when the solid solution-aqueous solutions system is near to equilibrium, which can occur in scenarios where the supersaturation rate and hence the supersaturation level are relatively small.

We combined statistical analyses and GIS capabilities within the statistical environment R to create a semi-automated method for the assessment of As hazard risk in shallow groundwater in Cambodia. Arsenic concentration data for groundwaters of between 16 and 100 m depth were obtained from 1437 geo-referenced wells. We created a binary logistic regression model with these As measurements as the dependent variable and a number of raster maps (DEM-parameters, remote sensing images and geomorphology) as explanatory variables, and considering an As threshold of 10 ppb. This allowed us to make an As hazard map for groundwaters between 16—100 m depth: this can be used to help to identify populations vulnerable to exposure. The logistic regression analysis indicates a good correlation between topographic and geomorphologic environmental variables and the As hazard risk in groundwater. Ease of implementation, and the ability to update, along with objectivity and reproducibility are the main advantages related to this method of analysis.

In many areas of south and south-eastern Asia, concentrations of As in ground water have been found to exceed the WHO maximum concentration limit of 10 μg/l. This is adversely affecting the health of millions of people and has grave current and future health implications. It has recently been suggested that extensive abstraction of ground water in these areas may accelerate the release of As to ground water. This study uses geochemical and isotopic data to assess this hypothesis. The area investigated in this study is in the Chakdaha block of the Nadia District, West Bengal. The ground water is predominantly of the Ca-Mg-HCO3 type, although some samples were found to contain elevated concentrations of Na, Cl and SO4. This is thought to reflect a greater degree of water-rock interaction at the locations of these particular samples. Arsenic concentrations exceeded the national limit of 50 μg/l in 13 of the 22 samples collected. Four of the 13 samples with high As were recovered from tubewells with depths of 60 m or more. Shallow ground water samples were found to have a stable isotopic composition which falls subparallel to the Global Meteoric Water Line. This probably represents a contribution of evaporated surface water to the ground water, possibly from surface ponds or re-infiltrating irrigation water. Deep ground water, conversely, was shown to have a composition that closely reflects that of meteoric water. The data presented in this study suggest that, whilst the drawdown of surface waters may drive As release in shallow ground waters, it is not responsible for driving As release in deep ground water. However, local abstraction may have resulted in changes in the ground water flow regime of the area, with contaminated shallow ground waters being drawn into previously uncontaminated deep aquifers.

In spite of significant concerns about Hg contamination and its toxic impacts in the environment, limited studies have been carried out in Korea. The objectives of this study are to investigate the extent and degree of Hg contamination in soil, sediment, dust and sludge from various anthropogenic sources in Korea, and to understand the distribution patterns of Hg in the study areas. The anthropogenic sources of Hg contamination were divided into four major sources: (1) by-product from abandoned Au-Ag mines; (2) coal combustion; (3) cement production; and (4) industrial and domestic discharges. A calculation of enrichment factor and index of geoaccumulation for Hg in soils and sediments indicated that some samples from mining sites were enriched in Hg. In addition, Hg concentrations in marine sediments from industrial sites were above the Effects Range Median (ERM) criteria suggested by the National Oceanic and Atmospheric Administration of the United States (NOAA). Therefore, it can be concluded that samples from various sites were directly influenced by anthropogenic sources of Hg in the surface environment.

This paper describes the design, testing and validation of a simple and inexpensive spectrophotometric method for total Se analysis in aqueous solution based on the azo coupling reaction of amines. In this reaction, selenite ions react with hydroxylamine hydrochloride (NH2OH.HCl), which in turn diazotizes p-Nitroaniline and is coupled with N-1-naphthyl-ethylenediamine dihydrochloride (NEDA) to form a red coloured azo compound. This azo compound has a maximum absorption peak at 545 nm, an apparent molar absorption of 2.85x104 l mol-1 cm-1 and it follows the Beer’s law in the range from 0.01 to 2.50 mg/l with R2 = 0.9998. Interferences between the azo reaction and non-targeted ions often present in environmental samples (i.e., NO3-, CO3-, Cl- or metals) were investigated and specific protocols to overcome them were implemented. The advantages of the new method for low levels of Se in aqueous solutions are its high sensitivity and reproducibility, and the fact that measurements are simple, rapid and low-cost.

To trace the historyof anthropogenic, atmospheric Pb pollution, analyses of soils from the region and of cores from the karst Lake Vrana (Croat: Vransko jezero) on the island of Cres were performed. The area affected byPb pollution in Croatia covers most of the high-mountain karst region. Since lake sediments can act as archives of atmospheric deposition of metals (and other pollutants) a multi-element analysis as well as Pb isotopes of dated sediment core samples and palaeosoil from the catchment enabled the evaluation of Pb-pollution history. The Pb/Sc ratios and the 206Pb/207Pb ratios allowed the calculation of enrichment factors and the anthropogenic contributions of Pb during the past 4000 y. The sediments of Lake Vrana were found to be a consistent record of Pb pollution in this part of the Mediterranean region, despite the fact that the catchment lost most of its soil cover between 1404 and 1650 AD due to deforestation which caused a major change in sediment composition.

Soluble inorganic As is toxic with both cancer and non-cancer endpoints. Of the 80 million people in West Bengal, 50 million are living in the nine As-affected districts with millions at risk from using water for drinking, cooking or irrigation (Chakraborti et al., 2004). An environmental tragedy is developing in West Bengal with an alarming number of cases of skin lesions (Guha Mazumder et al., 1998; Mukherjee et al., 2005), respiratory symptoms (von Ehrenstein et al., 2005), adverse pregnancy outcomes and infant mortality (von Ehrenstein et al., 2006) and neurological complications (Mukherjee et al., 2005) associated with ingestion of As-contaminated water.