Filters: Contacts: Kent, Douglas B (X)
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We examined the chemical reactions influencing dissolved concentrations, speciation, and transport of naturally occurring arsenic (As) in a shallow, sand and gravel aquifer with distinct geochemical zones resulting from land disposal of dilute sewage effluent. The principal geochemical zones were: (1) the uncontaminated zone above the sewage plume [350 µM dissolved oxygen (DO), pH 5.9]; (2) the suboxic zone (5 µM DO, pH 6.2, elevated concentrations of sewage-derived phosphate and nitrate); and (3) the anoxic zone [dissolved iron(II) 100–300 µM, pH 6.5–6.9, elevated concentrations of sewage-derived phosphate]. Sediments are comprised of greater than 90% quartz but the surfaces of quartz and other mineral grains are...
Categories: Publication;
Types: Citation;
Tags: Arsenic,
Contamination,
Geochemistry,
Groundwater,
qua
The discharge of a plume of sewagecontaminated ground water emanating from the Massachusetts Military Reservation to Ashumet Pond on Cape Cod, Massachusetts, has caused concern about excessive loading of nutrients, particularly phosphorus, to the pond. The U.S. Air Force is considering remedial actions to mitigate potentially adverse effects on the ecological characteristics of the pond from continued phosphorus loading. Concentrations as great as 3 milligrams per liter of dissolved phosphorus (as P) are in ground water near the pond‘s shoreline; concentrations greater than 5 milligrams per liter of phosphorus are in ground water farther upgradient. Temporary drive-point wells were used to collect water samples...
Categories: Publication;
Types: Citation
The discharge of a plume of sewagecontaminated ground water emanating from the Massachusetts Military Reservation to Ashumet Pond on Cape Cod, Massachusetts, has caused concern about excessive loading of nutrients, particularly phosphorus, to the pond. The U.S. Air Force is considering remedial actions to mitigate potentially adverse effects on the ecological characteristics of the pond from continued phosphorus loading. Concentrations as great as 3 milligrams per liter of dissolved phosphorus (as P) are in ground water near the pond‘s shoreline; concentrations greater than 5 milligrams per liter of phosphorus are in ground water farther upgradient. Temporary drive-point wells were used to collect water samples...
Categories: Publication;
Types: Citation
Dispersive transport of groundwater solutes was investigated as part of a multispecies reactive tracer test conducted under spatially variable chemical conditions in an unconfined, sewage-contaminated sand and gravel aquifer on Cape Cod, Massachusetts. Transport of the nonreactive tracer bromide (Br) reflected physical and hydrologic processes. Transport of the reactive tracer nickel (Ni) complexed with an organic ligand (NiEDTA) varied in response to pH and other chemical conditions within the aquifer. A loss of about 14% of the Ni mass was calculated from the distribution of tracers through time. This loss is consistent with reversible adsorption of NiEDTA onto the iron and aluminum oxyhydroxide coatings on the...
Categories: Publication;
Types: Citation;
Tags: Groundwa,
groundwater hydrology,
groundwater quality
Adsorption, complexation, and dissolution reactions strongly influenced the transport of metal ions complexed with ethylenediaminetetraacetic acid (EDTA) in a predominantly quartz-sand aquifer during two tracer tests conducted under mildly reducing conditions at pH 5.8 to 6.1. In tracer test M89, EDTA complexes of zinc (Zn) and nickel (Ni), along with excess free EDTA, were injected such that the lower portion of the tracer cloud traveled through a region with adsorbed manganese (Mn) and the upper portion of the tracer cloud traveled through a region with adsorbed Zn. In tracer test S89, Ni- and Zn-EDTA complexes, along with excess EDTA complexed with calcium (Ca), were injected into a region with adsorbed Mn. The...
Categories: Publication;
Types: Citation
Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1?4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen...
Categories: Publication;
Types: Citation
A plume of contaminated groundwater extends from former disposal beds at the Massachusetts Military Reservation‘s wastewater-treatment plant toward Ashumet Pond, coastal ponds, and Vineyard Sound, Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to the rapid-infiltration beds for nearly 60 years before the disposal site was moved to a different location in December 1995. Water-quality samples were collected from monitoring wells, multilevel samplers, and profile borings to characterize the nature and extent of the contaminated groundwater and to observe the water-quality changes after the wastewater disposal ceased. Data are presented here for water samples collected in 2007 from 394 wells...
Categories: Publication;
Types: Citation
In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments...
Categories: Publication;
Types: Citation;
Tags: Hanford,
Kine,
groundwater–surface water interaction
Mineralogical studies of coatings on quartz grains and bulk sediments from an aquifer on Western Cape Cod, Massachusetts, USA were carried out using a variety of transmission electron microscopy (TEM) techniques. Previous studies demonstrated that coatings on quartz grains control the adsorption properties of these sediments. Samples for TEM characterization were made by a gentle mechanical grinding method and focused ion beam (FIB) milling. The former method can make abundant electron-transparent coating assemblages for comprehensive and quantitative X-ray analysis and the latter technique protects the coating texture from being destroyed. Characterization of the samples from both a pristine area and an area heavily...
A plume of contaminated ground water extends from former disposal beds at the Massachusetts Military Reservation wastewater-treatment plant toward Ashumet Pond, and farther southward toward coastal ponds and Vineyard Sound, Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to the rapid-infiltration beds for nearly 60 years before the disposal site was moved to a different location in December 1995. Water-quality samples were collected periodically from monitoring wells and multilevel samplers during and after the disposal period to characterize the nature and extent of the contaminated ground water and to observe the water-quality changes after the wastewater disposal ceased. Data are presented...
Categories: Publication;
Types: Citation
Tracer tests were performed in distinct biogeochemical zones of a sand and gravel aquifer in Cape Cod, MA, to study the redox chemistry (I) and transport (Cs, I) of cesium and iodine in a field setting. Injection of iodide (I?) into an oxic zone of the aquifer resulted in oxidation of I? to molecular iodine (I2) and iodate (IO3?) over transport distances of several meters. Oxidation is attributed to Mn-oxides present in the sediment. Transport of injected IO3? and Cs+ was retarded in the mildly acidic oxic zone, with retardation factors of 1.6?1.8 for IO3? and 2.3?4.4 for Cs. Cs retardation was likely due to cation exchange reactions. Injection of IO3? into a Fe-reducing zone of the aquifer resulted in rapid and...
Categories: Publication;
Types: Citation
Uranium adsorption?desorption on sediment samples collected from the Hanford 300-Area, Richland, WA varied extensively over a range of field-relevant chemical conditions, complicating assessment of possible differences in equilibrium adsorption properties. Adsorption equilibrium was achieved in 500?1000 h although dissolved uranium concentrations increased over thousands of hours owing to changes in aqueous chemical composition driven by sediment-water reactions. A nonelectrostatic surface complexation reaction, >SOH + UO22+ + 2CO32- = >SOUO2(CO3HCO3)2?, provided the best fit to experimental data for each sediment sample resulting in a range of conditional equilibrium constants (logKc) from 21.49 to 21.76. Potential...
Categories: Publication;
Types: Citation
The fate of arsenic in groundwater depends largely on its interaction with mineral surfaces. We investigated the kinetics of As(III) oxidation by aquifer materials collected from the USGS research site at Cape Cod, MA, USA, by conducting laboratory experiments. Five different solid samples with similar specific surface areas (0.6–0.9 m2 g−1) and reductively extractable iron contents (18–26 μmol m−2), but with varying total manganese contents (0.5–3.5 μmol m−2) were used. Both dissolved and adsorbed As(III) and As(V) concentrations were measured with time up to 250 h. The As(III) removal rate from solution increased with increasing solid manganese content, suggesting that manganese oxide is responsible for the oxidation...
Categories: Publication;
Types: Citation
Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1?4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen...
Categories: Publication;
Types: Citation
A plume of contaminated groundwater extends from former disposal beds at the Massachusetts Military Reservation‘s wastewater-treatment plant toward Ashumet Pond, coastal ponds, and Vineyard Sound, Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to the rapid-infiltration beds for nearly 60 years before the disposal site was moved to a different location in December 1995. Water-quality samples were collected from monitoring wells, multilevel samplers, and profile borings to characterize the nature and extent of the contaminated groundwater and to observe the water-quality changes after the wastewater disposal ceased. Data are presented here for water samples collected in 2007 from 394 wells...
Categories: Publication;
Types: Citation
Disposal of treated wastewater for more than 60 years onto infiltration beds on Cape Cod, Massachusetts produced a groundwater contaminant plume greater than 6 km long in a surficial sand and gravel aquifer. In December 1995 the wastewater disposal ceased. A long-term, continuous study was conducted to characterize the post-cessation attenuation of the plume from the source to 0.6 km downgradient. Concentrations and total pools of mobile constituents, such as boron and nitrate, steadily decreased within 1?4 years along the transect. Dissolved organic carbon loads also decreased, but to a lesser extent, particularly downgradient of the infiltration beds. After 4 years, concentrations and pools of carbon and nitrogen...
Categories: Publication;
Types: Citation
A plume of contaminated groundwater extends from former disposal beds at the Massachusetts Military Reservation‘s wastewater-treatment plant toward Ashumet Pond, coastal ponds, and Vineyard Sound, Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to the rapid-infiltration beds for nearly 60 years before the disposal site was moved to a different location in December 1995. Water-quality samples were collected from monitoring wells, multilevel samplers, and profile borings to characterize the nature and extent of the contaminated groundwater and to observe the water-quality changes after the wastewater disposal ceased. Data are presented here for water samples collected in 2007 from 394 wells...
Categories: Publication;
Types: Citation
The fate of arsenic in groundwater depends largely on its interaction with mineral surfaces. We investigated the kinetics of As(III) oxidation by aquifer materials collected from the USGS research site at Cape Cod, MA, USA, by conducting laboratory experiments. Five different solid samples with similar specific surface areas (0.6–0.9 m2 g−1) and reductively extractable iron contents (18–26 μmol m−2), but with varying total manganese contents (0.5–3.5 μmol m−2) were used. Both dissolved and adsorbed As(III) and As(V) concentrations were measured with time up to 250 h. The As(III) removal rate from solution increased with increasing solid manganese content, suggesting that manganese oxide is responsible for the oxidation...
Categories: Publication;
Types: Citation
Two experimental permeable reactive barriers (PRBs) of granular zero-valent iron were emplaced in the path of a tetrachloroethene plume (the Chemical Spill-10 plume) at the Massachusetts Military Reservation, Cape Cod, Massachusetts, in June 1998. The goal of the field experiment was to achieve emplacement of a granular-iron PRB deeper than attempted before. The PRBs were expected to create a reducing environment and degrade the tetrachloroethene by reductive dechlorination. The goal of the work presented in this report was to observe temporary and sustained changes to the ground-water chemistry downgradient from the PRBs. A hydraulic-fracturing method involving injection of the granular iron with a guar-biopolymer...
Categories: Publication;
Types: Citation
A plume of contaminated ground water extends from former disposal beds at the Massachusetts Military Reservation wastewater-treatment plant toward Ashumet Pond, and farther southward toward coastal ponds and Vineyard Sound, Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to the rapid-infiltration beds for nearly 60 years before the disposal site was moved to a different location in December 1995. Water-quality samples were collected periodically from monitoring wells and multilevel samplers during and after the disposal period to characterize the nature and extent of the contaminated ground water and to observe the water-quality changes after the wastewater disposal ceased. Data are presented...
Categories: Publication;
Types: Citation
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