Michael Berg

Last Name

Berg

First Name

Michael

ORCID

0000-0002-7342-4061

Organisational unit

01709 - Lehre Umweltsystemwissenschaften

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Publications 1 - 10 of 15

Geostatistical modelling of arsenic hazard in groundwater
Bretzler, Anja; Berg, Michael; Winkel, Lenny; et al. (2017)
Metals and Related Substances in Drinking Water Series ~ Best Practice Guide on the Control of Arsenic in Drinking Water
Quecksilber im Schweizer Abwasser
Berg, Michael; Suess, Elke; Cayo, Lara; et al. (2021)
Aqua & Gas
Noble gases in aquitard provide insight into underlying subsurface stratigraphy and free gas formation
Lightfoot, Alexandra Kathryn; Stopelli, Emiliano; Berg, Michael; et al. (2023)
Vadose Zone Journal
Biogeochemical gas production resulting in free gas phase formation can severely affect groundwater and solute transport in aquifers. Such gas-water interactions are important in aquifers affected by geogenic As, which are commonly associated with biogeochemical CH4 production. Additionally, the influence of aquitards on As concentrations in contaminated aquifers has recently been challenged. These observations prompted the analysis through a heterogeneous aquitard overlying a high CH4-gas-producing zone of an As-contaminated aquifer. A sediment core taken through the aquitard was analyzed for noble gases to assess how the aquitard physically contributes to the underlying gas production. Results reveal that the aquitard pore space is unsaturated in two separate layers resulting in hanging pore water constrained by an air-like gas phase. This interlayering of unsaturated and saturated zones identifies the aquitard's stratigraphy as key in determining hydrostatic pressure-a main control of free gas formation (i.e., CH4) in the underlying aquifer. The partly unsaturated conditions reduce the hydrostatic pressure by 30% compared with fully saturated conditions. To our knowledge, this is the first study applying noble gases to examine the influence of an aquitards physical state on gas production in an underlying aquifer. Further, such partly unsaturated sediment layers of low conductivity might provide preferential pathways for periodic water flow, fostering aquitard-aquifer solute transport. Groundwater samples additionally collected throughout the study site confirm more widespread degassing than previously reported. Up to 90% of the expected atmospheric noble gas concentrations is lost from groundwater immediately below the investigated sediment core.
Arsenic Removal from Drinking Water: Experiences with Technologies and Constraints in Practice
Hering, Janet G.; Katsoyiannis, Ioannis A.; Theoduloz, Gerardo A.; et al. (2017)
Journal of Environmental Engineering
Treatment of drinking water for arsenic (As) removal has been implemented in centralized facilities worldwide, reflecting the increasingly stringent national and international drinking water standards for As, for which a standard of 10 μg/L has been widely adopted. It might therefore be expected that information on the performance of installed treatment processes could serve as basis for process optimization and more-informed decisions on process selection. A review of available information on installed treatment does provide some insight into the scale of implementation, factors driving process selection and difficulties that have arisen in practice (as a complement to more accessible information on bench-scale and pilot-scale studies). The availability of information on treatment performance at full-scale treatment is, however, severely limited. The rapid advances in information technology and consequent elimination of technical barriers to sharing information and knowledge should allow the development of an international, accessible database or even a metadata portal for installed technologies for As removal that would offer the potential to benefit from past and ongoing experience in practice.
Spatiotemporal Mineral Phase Evolution and Arsenic Retention in Microfluidic Models of Zerovalent Iron-Based Water Treatment
Wielinski, Jonas; Jimenez-Martinez, Joaquin; Göttlicher, Jörg; et al. (2022)
Environmental Science & Technology
Arsenic (As) is a toxic element, and elevated levels of geogenic As in drinking water pose a threat to the health of several hundred million people worldwide. In this study, we used microfluidics in combination with optical microscopy and X-ray spectroscopy to investigate zerovalent iron (ZVI) corrosion, secondary iron (Fe) phase formation, and As retention processes at the pore scale in ZVI-based water treatment filters. Two 250 μm thick microchannels filled with single ZVI and quartz grain layers were operated intermittently (12 h flow/12 h no-flow) with synthetic groundwater (pH 7.5; 570 μg/L As(III)) over 13 and 49 days. Initially, lepidocrocite (Lp) and carbonate green rust (GRC) were the dominant secondary Fe-phases and underwent cyclic transformation. During no-flow, lepidocrocite partially transformed into GRC and small fractions of magnetite, kinetically limited by Fe(II) diffusion or by decreasing corrosion rates. When flow resumed, GRC rapidly and nearly completely transformed back into lepidocrocite. Longer filter operation combined with a prolonged no-flow period accelerated magnetite formation. Phosphate adsorption onto Fe-phases allowed for downstream calcium carbonate precipitation and, consequently, accelerated anoxic ZVI corrosion. Arsenic was retained on Fe-coated quartz grains and in zones of cyclic Lp-GRC transformation. Our results suggest that intermittent filter operation leads to denser secondary Fe-solids and thereby ensures prolonged filter performance.
Quantification of Element Fluxes in Wastewaters: A Nationwide Survey in Switzerland
Vriens, Bas; Voegelin, Andreas; Hug, Stephan J.; et al. (2017)
Environmental Science & Technology
Arsenic mobilisation in a new well field for drinking water production along the Red River, Nam Du, Hanoi
Norrman, Jenny; Sparrenbom, Charlotte J.; Berg, Michael; et al. (2008)
Applied Geochemistry
Nitrate contamination in groundwater across Switzerland: Spatial prediction and data-driven assessment of anthropogenic and environmental drivers
Covatti, Gustavo; Li, Kai-Yun; Podgorski, Joel; et al. (2025)
Science of The Total Environment
Excessive nitrate in groundwater, which is primarily caused by anthropogenic activities, is a worldwide problem. Consequently, Goal 6 of the UN Sustainable Development Goals lists nitrate as one of the key indicators of groundwater quality. However, in most countries, the nationwide occurrence of nitrate is unknown, as the monitoring networks only represent small points in space. To bridge this gap, machine learning modelling that predicts nitrate concentrations at a high spatial resolution is a promising tool to identify high-risk areas. Here, we use random forest machine learning to predict nitrate concentrations across Switzerland based on 1336 monitoring sites. The model revealed that approximately 35 % of the Swiss Plateau, Switzerland's most populous region, has a high probability of exceeding the Swiss guideline value of 25 mg/l for groundwater nitrate. We also investigated the individual importance and influence of anthropogenic and environmental variables associated with high nitrate concentrations by combining SHapley Additive exPlanations with expert knowledge of physical and geochemical processes. In addition to well-known influences of anthropogenic features (e.g. land use), we found that other environmental features including high springtime precipitation, low summertime precipitation, low soil organic carbon content, low river density and greater distance to large rivers, were indicative of high nitrate concentrations. These features directly relate to large-scale nitrate transport and attenuation processes (denitrification and dilution), but have received sparse attention in nitrate risk assessment and mitigation measures. Therefore, the approach and results of our study can be useful for nitrate studies around the world.
Arsenic mobilization by anaerobic iron-dependent methane oxidation
Glodowska, Martyna; Stopelli, Emiliano; Schneider, Magnus; et al. (2020)
Communications Earth & Environment
Arsenic groundwater contamination threatens the health of millions of people worldwide, particularly in South and Southeast Asia. In most cases, the release of arsenic from sediment was caused by microbial reductive dissolution of arsenic-bearing iron(III) minerals with organic carbon being used as microbial electron donor. Although in many arsenic-contaminated aquifers high concentrations of methane were observed, its role in arsenic mobilization is unknown. Here, using microcosms experiments and hydrogeochemical and microbial community analyses, we demonstrate that methane functions as electron donor for methanotrophs, triggering the reductive dissolution of arsenic-bearing iron(III) minerals, increasing the abundance of genes related to methane oxidation, and ultimately mobilizing arsenic into the water. Our findings provide evidence for a methane-mediated mechanism for arsenic mobilization that is distinct from previously described pathways. Taking this together with the common presence of methane in arsenic-contaminated aquifers, we suggest that this methane-driven arsenic mobilization may contribute to arsenic contamination of groundwater on a global scale.
Arsenic and Other Geogenic Contaminants in Groundwater – A Global Challenge
Hug, Stephan J.; Winkel, Lenny H.E.; Voegelin, Andreas; et al. (2020)
Chimia
Groundwater is a much safer and more dependable source of drinking water than surface water. However, natural (geogenic) hazardous elements can contaminate groundwater and lead to severe health problems in consumers. Arsenic concentrations exceeding the WHO drinking water guideline of 10 μg/L globally affect over 220 million people and can cause arsenicosis (skin lesions and cancers). Fluoride, while preventing caries at low concentrations, has detrimental effects when above the WHO drinking water guideline of 1.5 mg/L and puts several hundred million people at risk of dental and skeletal fluorosis. In this article, we report on the geochemistry and occurrence of arsenic and fluoride in groundwater and on the development of global and regional risk maps that help alert governments and water providers to take appropriate mitigation measures for the provision of safe drinking water. We then summarize research on the removal of arsenic and fluoride from drinking water, focusing on adapted technologies for water treatment. Finally, we discuss the applicability of various measures in a larger context and future challenges in reaching the goal of access to safe drinking water for all.

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Michael Berg

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