Price, Roy
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Price, Roy
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Price, Roy
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Price, R.
Price, R. E.
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Item type:Publication, Energy sources for chemolithotrophs in an arsenic- and iron-rich shallow-sea hydrothermal systemThe hydrothermally influenced sediments of Tutum Bay, Ambitle Island, Papua New Guinea, are ideal for investigating the chemolithotrophic activities of micro-organisms involved in arsenic cycling because hydrothermal vents there expel fluids with arsenite (AsIII) concentrations as high as 950 μg L−1. These hot (99 °C), slightly acidic (pH ∼6), chemically reduced, shallow-sea vent fluids mix with colder, oxidized seawater to create steep gradients in temperature, pH, and concentrations of As, N, Fe, and S redox species. Near the vents, iron oxyhydroxides precipitate with up to 6.2 wt% arsenate (AsV). Here, chemical analyses of sediment porewaters from 10 sites along a 300-m transect were combined with standard Gibbs energies to evaluate the energy yields (−ΔGr) from 19 potential chemolithotrophic metabolisms, including AsV reduction, AsIII oxidation, FeIII reduction, and FeII oxidation reactions. The 19 reactions yielded 2–94 kJ mol−1 e−, with aerobic oxidation of sulphide and arsenite the two most exergonic reactions. Although anaerobic AsV reduction and FeIII reduction were among the least exergonic reactions investigated, they are still potential net metabolisms. Gibbs energies of the arsenic redox reactions generally correlate linearly with pH, increasing with increasing pH for AsIII oxidation and decreasing with increasing pH for AsV reduction. The calculated exergonic energy yields suggest that micro-organisms could exploit diverse energy sources in Tutum Bay, and examples of micro-organisms known to use these chemolithotrophic metabolic strategies are discussed. Energy modeling of redox reactions can help target sampling sites for future microbial collection and cultivation studies.journal articleBand:9Heft:571 180 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Geochemistry of Champagne Hot Springs shallow hydrothermal vent field and associated sediments, Dominica, Lesser AntillesThe Champagne Hot Springs (CHS) shallow submarine hydrothermal system is located along the submerged flank of the Plat Pays volcanic system on the southwest section of the island of Dominica, Lesser Antilles. We have conducted a detailed geochemical study of the hydrothermal system, with the objectives to investigate the source of the hydrothermal fluids and gases, their effect on sediment and precipitate chemistry, as well as comparing the submarine vent chemistry with nearby on-land hydrothermal vents. Finally, we compare our findings to previous preliminary data from CHS, and compare sediment chemistry to that of average Caribbean sediments. We also report on a newly discovered area of submarine hydrothermal venting, located approximately 40 m to the north of CHS. This area consists of hydrothermally altered areas of sand that contain abundant coatings of hydrous ferric oxides (HFO) on sediment grains. Geochemical and mineralogical analyses of vent waters, pore waters, gases, sediments and precipitates reveal that the vent fluids consist of a mixture of entrained seawater and meteorically derived hydrothermal fluid in varying proportions. Vent fluids are depleted in Br−, SO42−, Cl−, Na+, K+, and Sr2+ relative to ambient seawater. These species are all positively correlated with Mg2+, which is also depleted relative to seawater. Boron, Fe, As, Sb, Mn, Si and Li are all enriched relative to ambient seawater. Pore waters in the hydrothermally altered sand patches have essentially the same chemistry. Mixing between Fe2+ rich vent fluids and seawater causes rapid oxidation of Fe2+ to insoluble Fe3+ and leads to precipitation of HFO at the vent site and subsequent formation of hydrothermally altered sand patches. The elevated concentrations of As and Sb in the precipitates and sediments relative to average Caribbean seafloor sediments reflect adsorption by HFO. Gas samples from the vent site are typical arc-type gases and have both meteoric and magmatic signatures.journal articleBand:224Heft:1-361 60 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Amorphous arsenic sulfide nanoparticles in a shallow water hydrothermal system(Elsevier Science, 2019-04-23); ; ; ; Hydrothermal fluids can contain trace elements such as arsenic (As), which are toxic to surrounding biota. In these kind of fluids, the bioavailability and biotransformation of As have been investigated but so far the ratio of total soluble As (<200 nm) versus the amount of As contained in a nanoparticulate phase has not been reported. Here, for the first time, the presence of As in the nanoparticulate fraction (between 200 and 20 nm) is described for arsenic-rich hydrothermal fluids in a marine shallow-water hydrothermal system. Samples of diffusively venting hydrothermal fluids, pore-water and seawater were collected in the hydrothermal system located in Paleochori Bay, Milos Island (Greece), and the fraction between 200 and 20 nm (As200-20) was studied. Up to 38% of the soluble arsenic was present within the As200-20 fraction in pore fluids, 10 to 20% in hydrothermal fluids and 5% in seawater. Identification and characterization of particles in hydrothermal fluid, pore-water and seawater was performed by scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) with selected area electron diffraction (SAED) and dynamic light scattering (DLS). The particles are of spherical morphology with a polydisperse size distribution (PDI: 0.37) and diameters close to 100 nm. EDX studies confirmed a chemical composition rich in As and S. The SAED pattern revealed absence of a crystal phase indicating the presence of an amorphous arsenic sulfide material. These results bring into discussion the role of the nanoparticulate fraction for As dispersion, bioavailability, and potentially harmful effects in marine coastal ecosystems.journal articleBand:211100 163 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Arsenic bioaccumulation and biotransformation in deep-sea hydrothermal vent organisms from the PACMANUS hydrothermal field, Manus Basin, Papua New Guinea(Elsevier Science, 2016-11); ; ; ; Hydrothermal vents are often enriched in arsenic, and organisms living in these environments may accumulate high concentrations of this and other trace elements. However, very little research to date has focused on understanding arsenic bioaccumulation and biotransformation in marine organisms at deep-sea vent areas; none to date have focused organisms from back-arc spreading centers. We present for the first time concentration and speciation data for As in vent biota from several hydrothermal vent fields in the eastern Manus basin, a back-arc basin vent field located in the Bismark Sea, western Pacific Ocean. The gastropods Alviniconcha hessleri and Ifremeria nautilei, and the mussel Bathymodiolus manusensis were collected from diffuse venting areas where pH was slightly lower (6.2–6.8), and temperature (26.8–10.5 °C) and arsenic concentrations (169.5–44.0 nM) were higher than seawater. In the tissues of these organisms, the highest total measured As concentrations were in the gills of A. hessleri (5580 mg kg−1), with 721 mg kg−1 and 43 mg kg−1 in digestive gland and muscle, respectively. I. nautilei contained 118 mg kg−1 in the gill, 108 mg kg−1 in the digestive gland and 22 mg kg−1 in the muscle. B. manusensis contained 15.7 mg kg−1 in the digestive gland, followed by 9.8 mg kg-1 and 4.5 mg kg-1 in its gill and muscle tissue, respectively. We interpret the decreasing overall total concentrations in each organism as a function of distance from the source of hydrothermally derived As. The high concentration of arsenic in A. hessleri gills may be associated with elemental sulfur known to occur in this organism as a result of symbiotic microorganisms. Arsenic extracted from freeze-dried A. hessleri tissue was dominated by AsIII and AsV in the digestive gland (82% and 16%, respectively) and gills (97% AsIII, 2.3% AsV), with only 1.8% and 0.2% arsenobetaine (As-Bet) in the digestive gland and gills, respectively. However, the muscle contained substantial amounts of As-Bet (42% As-Bet compared to 48% AsIII and 10% AsV), suggesting As-Bet is a metabolite. Trace arsenosugar (SO4-sug) was observed in digestive gland and gills only. The other snail, I. nautilei, was also dominated by AsIII and AsV in digestive glands (82, 10%) and gills (80, 10%), with 6–9% As-Bet, but its muscle contained 62% As-Bet and 32% AsIII, with 7% trimethylarsoniopropionate (TMAP). Trace dimethylarsinic acid (DMAV) was observed in its gills, and trace TMAP and arsenocholine (AC) was observed in digestive glands. The mussel B. manusensis was dominated by As-Bet in all three tissue types. Digestive gland and gills contained ~22% AsIII, 5–10% AsV, 20–25% DMAV, along with some TMAP and tetramethylarsonium ion (TETRA). However, the muscle contained significantly more As-Bet (91.6%), with the only other species being AsIII (8.4%). Unfortunately, as is often the case in bioaccumulation and biotransformation studies, extraction efficiencies were low, limiting any rigorous interpretation of arsenic biotransformation patterns. Through process of elimination, we suggest that arsenosugars may be synthesized by H2S-oxidizing chemotrophic microbial mats, ultimately leading to the syntheses of As-Bet within vent organisms. However, because As-sugs rarely occur in deep-sea vent organisms, As-Bet, as well as TMAP, AC, and TETRA could also potentially be synthesized directly by the “Edmonds” pathway, the proposed arseno-analog to amino acid formation, without the necessity for arsenosugar formation as an intermediate. Future research should endeavor for more comprehensive extraction of organoarsenicals.journal articleBand:11748 80 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Mercury in the hydrothermal fluids and gases in Paleochori Bay, Milos, Greece(Elsevier Science, 2021-06-20); ; ; Seafloor hydrothermal activity may constitute a considerable mercury (Hg) source to the oceans, but the flux from marine shallow-water hydrothermal systems (MSWHS) remains poorly constrained to date. To study the presence of Hg in MSWHS in Paleochori Bay (Milos Island, Greece), sea surface, bottom, pore fluid and hydrothermal gas samples were collected in June of 2017, October of 2018 and July of 2020, and analyzed for Cl, Br, SO4, As, Ca, Fe, K, Mg, Mn, Na, Si, Sr, H2S, unfiltered total Hg (THg), and filtered Hg (Hgdiss). Specific sites were selected for the analysis of volatile elemental Hg (Hgo), dimethylmercury (DMHg), monomethylmercury (MMHg), and Hg in the gas phase (Hggas). Concentrations of THg observed in samples collected from the sea surface were elevated compared to surface samples taken outside Paleochori Bay. The highest surface water concentrations (~10 to 15 pM) were measured in samples collected directly above shallow-water hydrothermal discharge areas. Pore fluids outside Paleochori Bay were significantly lower in THg (0.8 to 8.6 pM) than those taken inside (17.4 to 1511 pM). Porewaters collected from areas with visible gaseous or fluid emission were highly variable but generally elevated in THg concentrations (185 to 5066 pM). Concentrations within gases ranged from 0.7 to 2791 nmol/m3. The vast majority of samples with highly elevated THg (> 100 pM) had low Na/K ratios (< 15), indicative of rapidly rising fluid. Concentrations of Hg0, DMHg, and MMHg were below detection limits in all samples. Bottom substrate type (e.g., rocky vs. sediment covered) likely affected infiltration rates of oxygenated seawater below the sediment-water interface, thereby affecting Hg speciation and removal by precipitation. Flux rates from porewaters compared to those with gaseous emission were high (12.56 to 1088 mol THg/year and 0.37 to 1.85 mol THg/year). Sites with slow gaseous emission rates are hypothesized to have extended subsurface reaction times, resulting in lower Hg concentrations emitted to bottom waters. However, increasing rates of gas emission did not necessarily indicate higher Hg concentrations. The scavenging of Hg in the sediments and advective flux out of Paleochori Bay likely prevent significant accumulations of THg in the water column of Paleochori Bay. The total atmospheric flux from Paleochori Bay using average flux calculations over the entire surface area would contribute 6 mmol Hg/year to the atmosphere. We hypothesize that Hg concentrations within the pore fluids of Paleochori Bay reflect a balance between mixing and precipitation in the subsurface. A three-component mixing system of vapor, brine and seawater determines THg concentrations; however, precipitation due to sulfur cycling, changes in redox conditions and temperature, all play a crucial role in removing Hg from emitted fluids and gases.journal articleBand:23367 73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Determination of arsenic concentration and distribution in the Floridan Aquifer SystemHere we report on the different sampling strategies for almost seven years of sampling rocks/sediments for the determination of As within the Intermediate Aquifer System (IAS) and upper Floridan Aquifer System (FAS), a very large and productive limestone aquifer spanning from Georgia into Florida. In the FAS, As contamination has become a recurring problem during aquifer storage and recovery (ASR), particularly in central and south Florida. To investigate these phenomena, samples from solid drill cores and rock cuttings were collected from the Hawthorn Group, Suwannee Limestone, Ocala Limestone and Avon Park Formation. Samples were taken along drill cores and rock cuttings (referred to as ‘interval’ samples) or from particular drill core sections and rock cuttings (referred to as ‘targeted’ samples) likely to contain elevated concentrations of As as indicated by the presence of pyrite, hydrous ferric oxide, organic matter, clay minerals, fracture surfaces, and high permeable (moldic) zones. Arsenic was present in all of the stratigraphic units at low concentrations, close to the global average for As in limestone of 2.6 mg/kg. The highest As concentration was 69 mg/kg. In all units, however, the average bulk As concentration in the targeted samples was substantially higher than that in the interval samples. Based on direct spot measurements by electron microprobe and indirect calculations, pyrite was identified as the main source of As in the FAS. Concentrations in pyrite ranged from less than 100 mg/kg to more than 11,000 mg/kg. Because pyrite is heterogeneously distributed, both vertically and horizontally in the sampled stratigraphic units, the same was observed for the distribution of As. However, As concentrations generally decreased with depth, i.e., highest As values in the Hawthorn Group and lowest As values in the Ocala Limestone and Avon Park Formation. Compared to pyrite, other trace minerals contained much less As. The average As concentrations of the two types of sample media (solid cores and rock cuttings) were quite similar. These results indicate that if simply the average bulk rock As concentration of a geologic unit is the desired outcome of an investigation, either interval or targeted sampling of rock cuttings, seems to be sufficient. This is particularly important when time and money are a factor. This approach could work equally well for any other trace element. Structural sedimentary information, such as fractures, etc., is likely lost, however, when sampling rock cuttings. Thus, if this information is required, solid core samples need to be collected by hollow core diamond drilling.journal articleBand:111Heft:3450 458 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Arsenic occurrence and speciation in Cyclope neritea, a gastropod inhabiting the arsenic-rich marine shallow-water hydrothermal system off Milos Island, GreeceAround Milos Island marine shallow-water hydrothermal activity can be found and in Paleochori Bay, where high arsenic concentrations were reported for the hydrothermal fluids. There the gastropod Cyclope neritea was present at high densities despite the extreme conditions associated with hydrothermal venting, feeding on white microbial mats. Surprisingly, C. neritea collected from the hydrothermal vent area accumulated comparatively less arsenic in its tissues than specimens of the same species collected from an area not affected by hydrothermal activity. Inorganic arsenic was found at high percentages with respect to the sum of arsenic species both in the gut and muscle of C. neritea and the amount of arsenobetaine (AB) was less than in specimens collected at an area away from hydrothermal activity. Trimethylarsoniopropionate (TMAP) was found at relatively high percentages in C. neritea and in the surrounding environment (sediment and plankton) in Paleochori Bay. Tetramethylarsonium ion (TETRA) was found at high percentages in the gut and muscle of C. neritea. It was most likely biosynthesized in the gastropod gut, and accumulated in the muscle, because it was not found in any other compartment studied. Based on these observations we conclude that C. neritea is arsenic tolerant. The data suggests that arsenic species distribution is strongly influenced by arsenic species exposure and/or different detoxifying mechanisms, although the exact metabolic pathways could not be completely resolved.journal articleBand:34896 114 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhanced geochemical gradients in a marine shallow-water hydrothermal system: Unusual arsenic speciation in horizontal and vertical pore water profilesThe shallow marine hydrothermal vents near Ambitle Island in eastern Papua New Guinea discharge hot, slightly acidic, As-rich, chemically reduced fluid into cool, slightly alkaline, oxygenated seawater. Gradients in temperature, pH, and total As (AsT), among others, are established as the two aqueous phases mix. The hydrothermal fluid contained ∼900 μg/L AsT, almost exclusively present as the reduced AsIII, while local seawater measured between 1.2 and 2.4 μg/L As, with approximately equal levels of AsIII and AsV. Of particular interest in this study was As speciation and abundance in pore waters as a function of sediment depth and as a function of distance from the area of focused venting. With increasing distance, AsT concentration in the pore water decreased rapidly, but remained elevated up to 300 m from the area of focused venting when compared to a non-hydrothermal control site. As a function of depth (to ∼100 cm) AsT concentration in the pore water profiles was elevated and generally increased with depth. Surprisingly, aqueous AsV far exceeded aqueous AsIII at almost all distances and depths investigated, while at the control site the AsIII concentration exceeded that of AsV. In the Tutum Bay hydrothermal system, chemical disequilibria among As species provide potential metabolic energy for arsenite oxidizing microorganisms where hydrothermal fluid mixes with seawater near the vent orifice, and for arsenate reducing microorganisms with increasing distance and depth from the hydrothermal point source.journal articleBand:22Heft:1276 54 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Enhanced bioaccumulation and biotransformation of As in coral reef organisms surrounding a marine shallow-water hydrothermal vent system(Elsevier Science, 2013-06-19); ; ; ; The marine shallow-water hydrothermal system in Tutum Bay, Ambitle Island, Papua New Guinea discharges as much as 1.5 kg of arsenic (As) per day into a coral reef ecosystem. Despite the amount of As released, coral reef organisms do not seem to be affected. We investigated the uptake and bioaccumulation of geothermally-derived inorganic As by the soft coral Clavularia sp., the calcareous algae Halimeda sp., and the sea squirt Polycarpa sp., by measuring the total As concentration (TAs) in tissues from each organism and comparing it to the same type of organism collected from a nearby control site. All organisms collected from the hydrothermal area displayed distinctly higher (2 to 20 times) TAs compared to the control site. Concentrations were typically higher in samples collected closer to the focused hydrothermal venting, which is the first direct evidence for enhanced bioaccumulation of As in organisms living within an area of hydrothermal influence. To assess As biotransformation to organoarsenicals, anionic and cationic As species were determined by IC-ICP-MS in methanol/water tissue extracts. The concentrations of several of the organoarsenic species were much higher at the hydrothermal vent site compared to the control site, and several organoarsenic species were present only in the hydrothermal samples, including some unidentifiable species. While intriguing, these speciation results cannot be interpreted robustly due to poor extraction efficiencies. Future researchers should attempt to improve the extraction efficiency to closer to 100%, which would allow a more accurate description of As biosynthesis pathways for the marine organisms living in these environments.journal articleBand:34889 111 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Abundance and mineralogical association of arsenic in the Suwannee Limestone (Florida): Implications for arsenic release during water–rock interactionArsenic (As) is being released from the Suwannee Limestone, Upper Floridan aquifer, during aquifer storage and recovery (ASR) cycle testing with concentrations of up to 130 μg/L in the recovered water. To determine the abundance and mineralogical association of As in the Suwannee Limestone matrix we have conducted a detailed mineralogical and geochemical study of 306 core samples. In addition to random sampling of core material, we also collected “targeted” samples of core material that contained organic material, hydrous ferric oxide, pyrite, phosphate minerals and clays. Bulk As concentrations were determined by acid digestion followed by hydride generation-atomic fluorescence spectrometry (HG-AFS). Specific mineral phases were analyzed using scanning electron microscopy (SEM) and electron-probe microanalyses (EPMA). The average As concentration for all 306 samples is 3.5 ppm, but only 1.7 ppm after exclusion of the “targeted” samples. The average for the “targeted” samples is 9.5 ppm. The detailed lithologic, mineralogical, and geochemical study of As in the Upper Floridan aquifer, Suwannee Limestone shows that: (1) Arsenic is present in the Suwannee Limestone in low concentrations, but is concentrated in minor mineral phases, particularly pseudo-framboidal pyrite. (2) Pyrite is generally As-rich and can contain concentrations between 100 and 11,200 ppm As (average 2300 ppm, n = 25). (3) Compared to pyrite, other trace minerals contain much less As. (4) Pyrite is ubiquitous throughout the Suwannee Limestone, but is most abundant in high porosity zones. (5) Previously suggested hydrous ferric oxide, clay minerals and apatite are not an important source of As. This study also provided some insight into the question whether the interaction (reaction) of water with an aquifer matrix that contains only a few part per million As is capable of producing high-As concentrations in groundwater. Our findings indicate that it can be relatively easy to generate a high-As groundwater despite a low bulk As concentration in the aquifer matrix. A change in physico-chemical conditions that selectively affects the stability of As-bearing minerals is sufficient to increase As concentrations by several orders of magnitude.journal articleBand:228Heft:1-388 99