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Appl Geochem 2017 Aug;83:31-40

U.S. Environmental Protection Agency, National Risk Management Research Laboratory, 26 W. Martin Luther King Dr. Cincinnati, OH 45268, United States.

A series of leaching and partitioning tests (Toxicity Characteristic Leaching Procedure (TCLP), Synthetic Precipitation Leaching Procedure (SPLP), Controlled Acidity Leaching Protocol (CALP), Acid Neutralization Capacity (ANC), and sequential extraction) were applied to three different soils to study the potential mobility of metals into groundwater. Two of these soils were lead (Pb)-contaminated soils (Hotspot 1 and Hotspot 2) collected from an urban site associated with lead smelting and other industrial operations. The third sample (Stockpile) was soil affected by previous contamination in the area, removed from residential properties, stockpiled, and selected to be used as fill material in the studied site. Read More

Appl Geochem 2017 Aug;83:121-135

Center for Watershed Protection, Ellicott City, MD 21043.

Human-dominated land uses can increase transport of major ions in streams due to the combination of human-accelerated weathering and anthropogenic salts. Calcium, magnesium, sodium, alkalinity, and hardness significantly increased in the drinking water supply for Baltimore, Maryland over almost 50 years (p<0.05) coinciding with regional urbanization. Read More

Appl Geochem 2017 Feb 11;77:24-30. Epub 2016 Oct 11.

Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964.

The sediments of Union Lake in Southern New Jersey are contaminated with arsenic released from the Vineland Chemical Company Superfund site 11 km upstream. Seasonal anoxia has been shown to release arsenic from sediments to similar lakes; this process was hypothesized as a major arsenic source to Union Lake. Data indicate, however, that releases of arsenic to bottom waters from the sediments or from pore waters within the sediments are relatively minor: bottom water arsenic concentrations reached ~30 ppb (~12 μM) at most, representing <13% of the dissolved arsenic content of the lake. Read More

Appl Geochem 2017 Feb 23;77:142-157. Epub 2015 Nov 23.

Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.

The spatial heterogeneity of dissolved arsenic (As) concentrations in shallow groundwater of the Bengal Basin has been attributed to transport of As (and reactive carbon) from external sources or to the release of As from within grey sand formations. We explore the latter scenario in this detailed hydrological and geochemical study along a 300 m transect of a shallow aquifer extending from a groundwater recharge area within a sandy channel bar to its discharge into a nearby stream. Within the 10-20 m depth range, groundwater ages along the transect determined by the H-He method increase from <10 yr in the recharge area to a maximum of 40 yr towards the stream. Read More

Appl Geochem 2017 Feb 15;77:167-177. Epub 2016 Mar 15.

Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.

Reductive dissolution of iron oxyhydroxides and reduction of arsenic are often invoked as leading causes of high dissolved As levels in shallow groundwater of Bangladesh. The second of these assumptions is questioned here by comparing the behavior As and phosphate (P), a structural analogue for As (V) which also adsorbs strongly to Fe oxyhydroxides but is not subject to reduction. The first line of evidence is provided by a detailed groundwater time-series spanning two years for three wells in the 6-9 m depth range showing removal of As(III) from shallow groundwater during the monsoon without of loss of P. Read More

Appl Geochem 2016 Apr;67:68-80

Environmental Systems Program, University of California, Merced 5200 North Lake Road, Merced, CA 95343, USA.

Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg L- and S K-edge. Read More

Appl Geochem 2015 Dec;63:647-660

Department of Geology, University of Dhaka, Dhaka 1000, Bangladesh.

Riverbank sediment cores and pore waters, shallow well waters, seepage waters and river waters were collected along the Meghna Riverbank in Gazaria Upazila, Bangladesh in Jan. 2006 and Oct.-Nov. Read More

Appl Geochem 2015 Nov 7;62:131-149. Epub 2015 Feb 7.

Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721.

Toxic metalliferous mine-tailings pose a significant health risk to ecosystems and neighboring communities from wind and water dispersion of particulates containing high concentrations of toxic metal(loid)s (e.g., Pb, As, Zn). Read More

Appl Geochem 2015 Mar;54:27-42

School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, The University of Manchester, Manchester M13 9PL, UK.

Highly reactive nano-scale biogenic magnetite (BnM), synthesized by the Fe(III)-reducing bacterium , was tested for the potential to remediate alkaline Cr(VI) contaminated waters associated with chromite ore processing residue (COPR). The performance of this biomaterial, targeting aqueous Cr(VI) removal, was compared to a synthetic alternative, nano-scale zero valent iron (nZVI). Samples of highly contaminated alkaline groundwater and COPR solid waste were obtained from a contaminated site in Glasgow, UK. Read More

Appl Geochem 2013 Nov;38:110-120

Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721.

The competitive adsorption of arsenate and arsenite with silicic acid at the ferrihydrite-water interface was investigated over a wide pH range using batch sorption experiments, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) modeling. Batch sorption results indicate that the adsorption of arsenate and arsenite on the 6-L ferrihydrite surface exhibits a strong pH-dependence, and the effect of pH on arsenic sorption differs between arsenate and arsenite. Arsenate adsorption decreases consistently with increasing pH; whereas arsenite adsorption initially increases with pH to a sorption maximum at pH 7-9, where after sorption decreases with further increases in pH. Read More

Appl Geochem 2013 Nov;38

Department of Soil, Water and Environmental Science, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building #38, P.O. Box 210038, Tucson, AZ, USA ; Department of Hydrology and Water Resources, School of Earth and Environmental Sciences, University of Arizona, 429 Shantz Building #38, P.O. Box 210038, Tucson, AZ, USA.

The remediation of ammonium-containing groundwater discharged from uranium mill tailing sites is a difficult problem facing the mining industry. The Monument Valley site is a former uranium mining site in the southwest US with both ammonium and nitrate contamination of groundwater. In this study, samples collected from 14 selected wells were analyzed for major cations and anions, trace elements, and isotopic composition of ammonium and nitrate. Read More

Appl Geochem 2010 Oct;25(10):1500-1509

Department of Earth and Environmental Sciences, Columbia University, Mail Code 5505, New York, NY, 10027, USA.

Arsenic is a prevalent contaminant at US Superfund sites where remediation by pump and treat systems is often complicated by slow desorption of As from Fe and Al (hydr)oxides in aquifer solids. Chemical amendments that either compete with As for sorption sites or dissolve Fe and Al (hydr)oxides can increase As mobility and improve pump and treat remediation efficiency. The goal of this work was to determine optimal amendments for improving pump and treat at As contaminated sites such as the Vineland Chemical Co. Read More

Appl Geochem 2009 Dec;42(12):2234-2245

Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721-0038, USA.

Desert mine tailings may accumulate toxic metals in the near surface centimeters because of low water through-flux rates. Along with other constraints, metal toxicity precludes natural plant colonization even over decadal time scales. Since unconsolidated particles can be subjected to transport by wind and water erosion, potentially resulting in direct human and ecosystem exposure, there is a need to know how the lability and form of metals change in the tailings weathering environment. Read More

Appl Geochem 2008 Nov;23(11):3019-3028

Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA.

One of the reasons the processes resulting in As release to groundwater in southern Asia remain poorly understood is the high degree of spatial variability of physical and chemical properties in shallow aquifers. In an attempt to overcome this difficulty, a simple device that collects groundwater and sediment as a slurry from precisely the same interval was developed in Bangladesh. Recently published results from Bangladesh and India relying on the needle-sampler are augmented here with new data from 37 intervals of grey aquifer material of likely Holocene age in Vietnam and Nepal. Read More

Appl Geochem 2008 Nov;23(11):3224-3235

Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA.

Microbial Fe reduction is widely believed to be the primary mechanism of As release from aquifer sands in Bangladesh, but alternative explanations have been proposed. Long-term incubation studies using natural aquifer material are one way to address such divergent views. This study addresses two issues related to this approach: (1) the need for suitable abiotic controls and (2) the spatial variability of the composition of aquifer sands. Read More

Appl Geochem 2000 Sep;15(8):1169-90

Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.

The Juan de Fuca Ridge is a hydrothermally active, sediment covered, spreading ridge situated a few hundred kilometres off the west coast of North America in the northeastern Pacific Ocean. Sediments from seven sites drilled during the Ocean Drilling Program (ODP) Legs 139 and 168 were analyzed for total hydrolyzable amino acids (THAA), individual amino acid distributions, total organic C (TOC) and total N (TN) contents. The aim was to evaluate the effects of hydrothermal stress on the decomposition and transformation of sedimentary amino acids. Read More

Appl Geochem 2000 Mar;15(3):355-68

Petroleum and Environmental Geochemistry Group, Oregon State University, Corvallis 97331, USA.

Cape Kalamba oil seeps occur at the south end of the Ubwari Peninsula, at the intersection of faults controlling the morphology of the northern basin of the Tanganyika Rift, East Africa. Oil samples collected at the surface of the lake 3-4 km offshore from Cape Kalamba have been studied. The aliphatic hydrocarbon and biomarker compositions, with the absence of the typical suite of polynuclear aromatic hydrocarbons, indicate an origin from hydrothermal alteration of immature microbial biomass in the sediments. Read More

Appl Geochem 2005 Apr;20(4):807-813

Lamont-Doherty Earth Observatory of Columbia University, 61 Rt 9W, Palisades, NY 10983, USA.

Elevated Pb levels in humans through environmental exposure are a significant health concern requiring scientific study of the sources of, and physiological response to this toxin. This requires a simple and precise method for measuring radiogenic Pb isotopes and Pb levels in blood. Presented here is a combination of methods for separation and analysis of Pb previously used predominantly for geologic samples. Read More