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At least 487 records · Page 27Linked to original sources
USGS1999

Storage Capacity and Water Quality of Lake Ngardok, Babeldaob Island, Republic of Palau, 1996-98

A bathymetric survey conducted during March and April, 1996, determined the total storage capacity Lake Ngardok to be between 90 and 168 acre-feet. Elevation-surface area and elevation-capacity curves summarizing the current relations among elevation, surface area, and storage capacity were created from the bathymetric map. Rainfall and lake-elevation data collected from April 1996 to March 1998 indicated that lake levels correlated to rainfall values with lake elevation rising rapidly in response to heavy rainfall and then returning to normal levels within a few days. Mean lake elevation for the 22 month period of data was 59.5 feet which gives a mean storage capacity of 107 acre-feet and a mean surface area of 24.1 acre. A floating mat of reeds, which covered 58 percent of the lake surface area at the time of the bathymetric survey, makes true storage capacity difficult to estimate. Water-quality sampling during April 1996 and November 1997 indicated that no U.S. Environmental Protection Agency primary drinking-water standards were violated for analyzed organic and inorganic compounds and radionuclides. With suitable biological treatment, the lake water could be used for drinking-water purposes. Temperature and dissolved oxygen measurements indicated that Lake Ngardok is stratified. Given that air temperature on Palau exhibits little seasonal variation, it is likely that this pattern of stratification is persistent. As a result, complete mixing of the lake is probably rare. Near anaerobic conditions exist at the lake bottom. Low dissolved oxygen (3.2 milligrams per liter) measured at the outflow indicated that water flowing past the outflow was from the deep oxygen-depleted depths of the lake.

Water-Resources Investigations Report↗
USGS1969

Evaluation and control of corrosion and encrustation in tube wells of the Indus Plains, West Pakistan

Seepage from rivers and irrigation canals has contributed to waterlogging and soil salinization problems in much of the Indus Plains of West Pakistan. These problems are being overcome in part by tube-well dewatering and deep leaching of salinized soils. The ground waters described here are anaerobic and some are supersaturated with troublesome minerals such as calcium carbonate (calcite) and iron carbonate (siderite). These waters are moderately corrosive to steel. Some wells contain sulfate-reducing bacteria, which catalyze corrosion, and pH-electrode potential relationships favorable to the solution of iron also are rather common. Corrosion is concentrated in the relatively active (anodic) saw slots of water-well filter pipes (screens), where metal loss is least tolerable. Local changes in chemical properties of the water, because of corrosion, apparently cause deposition of calcium carbonate, iron carbonate, and other minerals which clog the filter pipes. In some places well capacities are seriously reduced in very short periods of time. There appears to be no practicable preventive treatment for corrosion and encrustation in these wells. Even chemical sterilization for bacterial control has yielded poor results. Periodic rehabilitation by down-hole blasting or by other effective mechanical or chemical cleaning methods will prolong well life. It may be possible to repair severely damaged well screens by inserting perforated sleeves of plastic or other inert material. The most promising approach to future, well-field development is to use filter pipes of epoxy-resin-bonded fiber glass, stainless steel, or other inert material which minimizes both corrosion and corrosion-catalyzed encrustation. Fiberglass plastic pipe appears to be the most economically practicable construction material at this time and already is being used with promising results.

Water Supply Paper↗
USGS1979

Dissolved-oxygen depletion and other effects of storing water in Flaming Gorge Reservoir, Wyoming and Utah

The circulation of water in Flaming Gorge Reservoir is caused chiefly by insolation, inflow-outflow relationships, and wind, which is significant due to the geographical location of the reservoir. During 1970-75, there was little annual variation in the thickness, dissolved oxygen, and specific conductance of the hypolimnion near Flaming Gorge Dam. Depletion of dissolved oxygen occurred simultaneously in the bottom waters of both tributary arms in the upstream part of the reservoir and was due to reservoir stratification. Anaerobic conditions in the bottom water during summer stratification eventually results in a metalimnetic oxygen minimum in the reservoir. The depletion of flow in the river below Flaming Gorge Dam due to evaporation and bank storage in the reservoir for the 1963-75 period was 1,320 cubic hectometers, and the increase of dissolved-solids load in the river was 1,947,000 metric tons. The largest annual variations in dissolved-solids concentration in the river was about 600 milligrams per liter before closure of the dam and about 200 milligrams per liter after closure. The discharge weighted-average dissolved-solids concentration for the 5 years prior to closure was 386 milligrams per liter and 512 milligrams per liter after closure. The most significant changes in the individual dissolved-ion loads in the river during 1973-75 were the increase in sulfate (0.46 million metric tons), which was probably derived from the solution of gypsum, and the decrease in bicarbonate (0.39 million metric tons), which can be attributed to chemical precipitation. The maximum range in temperature in the Green River below the reservoir prior to closure of the dam in 1962 was from 0°C in winter to 21°C in summer. After closure until 1970 the temperature ranged from 2° to 12°C, but since 1970 the range has been from 4° to 9°C. The maximum range in temperature in the Green River below the reservoir prior to closure of the dam in 1962 was from 0°C in winter to 21°C in summer. After closure until 1970 the temperature ranged from 2° to 12°C, but since 1970 the range has been from 4° to 9°C.During September 1975, a massive algal bloom was observed in the upstream part of the reservoir. The bloom covered approximately 16 kilometers of the lower part of the Blacks Fork arm, 23 kilometers of the lower part of the Green River arm, and 15 kilometers of the main reservoir below the confluence of the two arms. By October 1975 the algal bloom had disappeared. Nutrient loading in the reservoir was not sufficient to maintain a rate of algal production that would be disastrous to the reservoir ecosystem. However, should the nutrient loading increase substantially, the quality of the reservoir water could probably deteriorate rapidly, and its use for recreation and water supply could be severely limited.

Utah, Wyoming↗
USGS1986

Hydrology of the Price River basin, Utah, with emphasis on selected coal-field areas

Data obtained during a hydrologic study of the Price River basin, Utah, are used to describe seasonal variations off low of springs, relation between ground water and surface water, hydraulic properties of the ground-water reservoir, ground-water recharge and discharge, flood characteristics of streams, mineralogic composition and depositional rates of sediments, nutrient and inorganic loading in streams and Scofield Reservoir, and water budgets for selected basins. Additional study and monitoring are needed to detect possible hydrologic changes caused by coal mining. Much of the ground-water discharge from the Star Point Sandstone in the Mesaverde Group in the Wasatch Plateau occurs along faults. In the Book Cliffs, where faulting is less extensive, most of the ground-water discharge is from the Flagstaff Limestone. The Flagstaff Limestone is greatly diffusive, has a small storage coefficient, and contains water which is perched. Springs issuing from the Star Point Sandstone in the Mud Creek drainage (Wasatch Plateau) had recession indexes greater than 365 days per log cycle. Springs issuing at higher altitudes from the Colton Formation and the Flagstaff Limestone in the Soldier Creek area (Book Cliffs) have great seasonal variability, with recession indexes ranging from 24 to 115 days per log cycle. Estimated transmissivities in the Soldier Creek area ranged from 0.003 foot squared per day in the lower part of the Castlegate Sandstone to 0.07 foot squared per day in the Price River Formation. Seepage from the Star Point Sandstone is the major contributor to base flow of the stream in Eccles Canyon (Wasatch Plateau). Gains of as much as 230 gallons per minute occurred near a fault zone which crosses Eccles Canyon at the junction with South Fork Canyon. The potentiometric surface of water in the Blackhawk Formation in the Wasatch Plateau (Mud Creek drainage) and the Book Cliffs (Soldier Creek area) generally is above the coal zones, and dewatering will be necessary in most places during mining. The total reported mine discharge during 1980 was about 2,800 acre-feet. During the 1980 water year, ground-water discharge from the Flagstaff Limestone contributed about 4,400 acre-feet, or 41 percent of the combined streamflow of Coal, Soldier, and Dugout Creeks. Discharge from the Blackhawk and other formations contributed about 2,200 acrefeet, or 21 percent of the streamflow. The recharge to a 4,020-acre outcrop of the Flagstaff Limestone in the Soldier Creek area was determined from measurements of the discharge of springs and seepage gains in streams. The estimated recharge was 2 inches per year, or 12 percent of the April 1 snowpack, or 9 percent of the precipitation during 1980. Benthic-diversity indexes at streams in the Book Cliffs and Wasatch Plateau are related to the size of the bed material. The Shannon-Weiner diversity index for five sites in the Mud Creek drainage ranged from 1.57 to 4.'20 during four sampling periods in 1979-80. In the Soldier Creek drainage, the diversity index for four sampling sites ranged from 0.8 to 2.3 during three sampling periods in 1979-80. Sediment deposition in Scofield Reservoir during 1943-79 was estimated to be 3,000 acre-feet but most of the coal deposition in the reservoir occurred prior to about 1950. An anaerobic zone develops in the reservoir during the summer, but water in the reservoir completely mixes during late summer or early fall.

Utah↗
USGS1996

Physical, chemical, and biological characteristics of the Charlotte Harbor basin and estuarine system in southwestern Florida: A summary of the 1982-89 U.S. Geological Survey Charlotte Harbor assessment and other studies

The Charlotte Harbor estuarine system, having a surface area of about 270 square miles, averages about 7 feet in depth and is connected to deep water of the Gulf of Mexico through several passes and inlets between barrier islands. Three major rivers flow into the estuary--the Peace, the Myakka, and the Caloosahatchee. Freshwater and tidal flushing transport nutrients and other constituents from the basin through the estuary into the gulf. Flushing characteristics were evaluated using a two-dimensional hydrodynamic model. The model indicated that the time required to flush injected dye (simulated) from some subareas of the harbor was longer for reduced freshwater inflow than for typical freshwater inflow. After 30 days of simulation of reduced freshwater inflow, 42 percent of the dye injected into the upper harbor remained in the upper harbor, compared to 28 percent for typical freshwater inflow. The Charlotte Harbor estuary is usually well mixed or partially mixed in the vertical, but vertical salinity stratification does occur, primarily during late summer when freshwater inflows are greatest. A box model was developed that incorporated vertically averaged salinities to account indirectly for three-dimensional transport processes associated with vertical stratification. The box model predicts that under high (7,592 cubic feet per second) and average (2,470 cubic feet per second) freshwater inflows from the Peace and Myakka Rivers, 50 percent of the original water (present at the start of the model run) would be flushed from the northern part of the estuarine system into the Gulf of Mexico in 10 days and 20 days, respectively. The distribution of plant nutrients in the Charlotte Harbor Estuary is affected by nutrient inputs, freshwater and tidal flushing, mixing, and recycling processes in the estuary. The distributions of total phosphorus and orthophosphate are affected mainly by river input and physical mixing. The distribution of ammonia nitrogen is variable and is related more to recycling within the estuary than to input from the rivers. Ammonia concentrations increase in deeper water, probably in response to vertical salinity stratification and low concentrations of dissolved oxygen that foster regeneration of ammonia from bottom sediments. The distribution of nitrite plus nitrate nitrogen is nonconservative--concentrations are high in the rivers and decrease more rapidly in the estuary than expected due to dilution with sea water, probably because of phytoplankton uptake. Phytoplankton productivity and biomass are usually greatest during late summer near the mouths of the tidal rivers when freshwater inflow and nutrient loading are greatest. The highly colored freshwater runoff reduces light penetration and phytoplankton productivity in regions of the estuary where salinity is less than about 10 parts per thousand, but the nutrient-rich, colored water is diluted by seawater at midsalinities (10-20 parts per thousand) so that availability of light increases and inorganic nitrogen concentrations are still high enough to stimulate productivity and growth of phytoplankton. In much of the estuary, salinity is greater than 20 parts per thousand, and availability of inorganic nitrogen, not light, limits productivity and growth. Although the Charlotte Harbor estuarine system is relatively undisturbed, much of its basin has been altered by human activities. Streamflow decreased substantially during 1931-84 in parts of the Peace River, probably because of ground-water withdrawals in the basin. Nutrient concentrations generally increased in the rivers during 1970-85, because of an increase in the flow of wastewater and agricultural runoff. The concentrations of phosphorus are naturally high in the Peace River because of extensive phosphate deposits in the basin. The phosphate deposits also are relatively rich in radionuclides of the uranium-238 series, including radium-226. In the upper basin, these deposits are exposed in the riverbed. Extensive phosphate mining and processing have exposed additional deposits to surface runoff. Periodic spills of phosphate sediments (slimes) have contributed additional phosphorus and radium-226 to the river and estuary. A single spill can contribute a phosphorus load equal to the annual loading in the Peace River at Arcadia. The projected increase in population in the basin by the year 2020 would generate an additional 60 million gallons per day of domestic wastewater over that generated during 1980, which would increase nitrogen loading in the basin by more than 3 tons per day. Intensified agricultural and industrial developments, particularly expanding citrus production and phosphate mining, could generate additional loads of nutrients and a variety of inorganic and organic contaminants. Increased inputs of nutrients, particularly nitrogen, could encourage growth and increase abundance of phytoplankton and benthic and epiphytic algae. If water were less colored as a result of reduced freshwater inflow, undesirable algal growth could be exacerbated because of increased availability of light. Increased abundance of phytoplankton and other algae could likely change dissolved-oxygen concentrations in the estuary, resulting in greater day-to-night fluctuations and the possible depletion of dissolved oxygen in deep water. At the present time, near-anaerobic conditions occur for days or weeks in the deep water (more than 9 feet) of the northern harbor during late summer. These conditions could become more persistent with time and over wider areas, if phytoplankton and other algae increase in abundance and in their contribution to benthic oxygen demand. An increased abundance of phytoplankton and other algae also would reduce light penetration and adversely affect seagrasses.

Florida↗
USGS2014

Methane oxidation linked to chlorite dismutation

We examined the potential for CH 4 oxidation to be coupled with oxygen derived from the dissimilatory reduction of perchlorate, chlorate, or via chlorite (ClO − 2 ) dismutation. Although dissimilatory reduction of ClO − 4 and ClO − 3 could be inferred from the accumulation of chloride ions either in spent media or in soil slurries prepared from exposed freshwater lake sediment, neither of these oxyanions evoked methane oxidation when added to either anaerobic mixed cultures or soil enriched in methanotrophs. In contrast, ClO − 2 amendment elicited such activity. Methane (0.2 kPa) was completely removed within several days from the headspace of cell suspensions of Dechloromonas agitata CKB incubated with either Methylococcus capsulatus Bath or Methylomicrobium album BG8 in the presence of 5 mM ClO − 2 . We also observed complete removal of 0.2 kPa CH 4 in bottles containing soil enriched in methanotrophs when co-incubated with D. agitata CKB and 10 mM ClO − 2 . However, to be effective these experiments required physical separation of soil from D. agitata CKB to allow for the partitioning of O 2 liberated from chlorite dismutation into the shared headspace. Although a link between ClO − 2 and CH 4 consumption was established in soils and cultures, no upstream connection with either ClO − 4 or ClO − 3 was discerned. This result suggests that the release of O 2 during enzymatic perchlorate reduction was negligible, and that the oxygen produced was unavailable to the aerobic methanotrophs.

Frontiers in Microbiology↗
USGS2013

A combined radio- and stable-isotopic study of a California coastal aquifer system

Stable and radioactive tracers were utilized in concert to characterize geochemical processes in a complex coastal groundwater system and to provide constraints on the kinetics of rock/water interactions. Groundwater samples from wells within the Dominguez Gap region of Los Angeles County, California were analyzed for a suite of major cations (Na + , K + , Mg 2+ , Ca 2+ ) and anions (Cl − , SO 4 2− ), silica, alkalinity, select trace elements (Ba, B, Sr), dissolved oxygen, stable isotopes of hydrogen (δD), oxygen (δ 18 O), dissolved inorganic carbon (δ 13 C DIC ), and radioactive isotopes ( 3 H, 222 Rn and 223,224,226,228 Ra). In the study area, groundwater may consist of a complex mixture of native groundwater, intruded seawater, non-native injected water, and oil-field brine water. In some wells, Cl − concentrations attained seawater-like values and in conjunction with isotopically heavier δ 18 O values, these tracers provide information on the extent of seawater intrusion and/or mixing with oil-field brines. Groundwater 3 H above 1 tritium unit (TU) was observed only in a few select wells close to the Dominguez Gap area and most other well groundwater was aged pre-1952. Based on an initial 14 C value for the study site of 90 percent modern carbon (pmc), groundwater age estimates likely extend beyond 20 kyr before present and confirm deep circulation of some native groundwater through multiple aquifers. Enriched values of groundwater δ 13 C DIC in the absence of SO 4 2− imply enhanced anaerobic microbial methanogenesis. While secular equilibrium was observed for 234 U/ 238 U (activity ratios ~1) in host matrices, strong isotopic fractionation in these groundwater samples can be used to obtain information of adsorption/desorption kinetics. Calculated Ra residence times are short, and the associated desorption rate constant is about three orders of magnitude slower than that of the adsorption rate constant. Combined stable- and radio-isotopic results provide unique insights into aquifer characteristics, such as geochemical cycling, rock/water interactions, and subsurface transport and mixing.

California↗
USGS2013

Net primary productivity of subalpine meadows in Yosemite National Park in relation to climate variability

Subalpine meadows are some of the most ecologically important components of mountain landscapes, and primary productivity is important to the maintenance of meadow functions. Understanding how changes in primary productivity are associated with variability in moisture and temperature will become increasingly important with current and anticipated changes in climate. Our objective was to describe patterns and variability in aboveground live vascular plant biomass in relation to climatic factors. We harvested aboveground biomass at peak growth from four 64-m 2 plots each in xeric, mesic, and hydric meadows annually from 1994 to 2000. Data from nearby weather stations provided independent variables of spring snow water content, snow-free date, and thawing degree days for a cumulative index of available energy. We assembled these climatic variables into a set of mixed effects analysis of covariance models to evaluate their relationships with annual aboveground net primary productivity (ANPP), and we used an information theoretic approach to compare the quality of fit among candidate models. ANPP in the xeric meadow was negatively related to snow water content and thawing degree days and in the mesic meadow was negatively related to snow water content. Relationships between ANPP and these 2 covariates in the hydric meadow were not significant. Increasing snow water content may limit ANPP in these meadows if anaerobic conditions delay microbial activity and nutrient availability. Increased thawing degree days may limit ANPP in xeric meadows by prematurely depleting soil moisture. Large within-year variation of ANPP in the hydric meadow limited sensitivity to the climatic variables. These relationships suggest that, under projected warmer and drier conditions, ANPP will increase in mesic meadows but remain unchanged in xeric meadows because declines associated with increased temperatures would offset the increases from decreased snow water content.

Western North American Naturalist↗
USGS2009

The application of induced polarization techniques to detect metal-bearing offshore anthropogenic waste and unexploded ordnance

Raw sewage and industrial waste have been dumped into sensitive estuaries, bays, and sounds for centuries. The full extents of the resulting sludge deposits are largely unknown, because they move in response to tidal and long‐shore currents, and because they are often buried by younger inert sediments. USGS field and laboratory measurements of toxic mine waste and organic effluent samples suggest that anthropogenic wastes typically contain finely‐divided metal and metal‐sulfide particles. The anoxic environment provided by anthropogenic wastes promotes the growth of anaerobic bacteria, creating a self‐reducing environment. We suggest that the finely‐divided metal and metal‐sulfide particles are the products of bacterial reduction and precipitation. The fine‐grained metallic precipitates are ideal targets for a surface‐effect electrochemical detection methodology called Induced Polarization (IP). A USGS‐patented (1998/2001) marine IP streamer technology has recently been commercialized and used to map “black smoker” sulfide deposits and their disseminated halos in the Bismarck Sea (2005), and titanium‐sand deposits offshore of South Africa (2007). The marine induced polarization system can do this mapping in three dimensions, more rapidly (it is towed at 3 knots), and with far higher resolution that land‐based measurements or vibracoring. Laboratory‐scale studies at the USGS suggest that anthropogenic wastes may display a specific multi‐frequency IP spectral signature that may be applicable to waste‐deposit mapping.

Conference Paper↗
USGS2003

Methanogenic activity in plankton samples and fish intestines A mechanism for in situ methanogenesis in oceanic surface waters

When plankton samples were incubated anaerobically with a cysteine-sulfide reducing agent, pronounced methane evolution occurred. This activity was inhibited by air, CHCl 3 , C 2 H 2 , and 2-bromoethanesulfonic acid. Adding [ 14 C]CO 3 2− resulted in accumulation of [ 14 C]CH 4 . Portions of the digestive tracts of three fishes were incubated in methanogenic media, and two of the samples showed the presence of methanogenic bacteria.

Limnology and Oceanography↗
USGS1999

Oxidation of ammonia and methane in an alkaline, saline lake

The oxidation of ammonia (NH 3 ) and methane (CH 4 ) was investigated in an alkaline saline lake, Mono Lake, California (U.S.A.). Ammonia oxidation was examined in April and July 1995 by comparing dark 14 CO 2 fixation rates in the presence or absence of methyl fluoride (MeF), an inhibitor of NH 3 oxidation. Ammonia oxidizer‐mediated dark 14 CO 2 fixation rates were similar in surface (5–7 m) and oxycline (11–15 m) waters, ranging between 70–340 and 89–186 nM d −1 , respectively, or 1–7% of primary production by phytoplankton. Ammonia oxidation rates ranged between 580–2,830 nM d −1 in surface waters and 732–1,548 nM d −1 in oxycline waters. Methane oxidation was examined using a 14 CH 4 tracer technique in July 1994, April 1995, and July 1995. Methane oxidation rates were consistently higher in July, and rates in oxycline and anaerobic bottom waters (0.5–37 and 7–48 nM d −1 , respectively) were 10‐fold higher than those in aerobic surface waters (0.04–3.8 nM d −1 ). The majority of CH 4 oxidation, in terms of integrated activity, occurred within anoxic bottom waters. Water column oxidation reduced the potential lake‐atmosphere CH 4 flux by a factor of two to three. Measured oxidation rates and water column concentrations were used to estimate the biological turnover times of NH 3 and CH 4 . The NH 3 pool turns over rapidly, on time scales of 0.8 d in surface waters and 10 d within the oxycline, while CH 4 is cycled on 10 3 ‐d time scales in surface waters and 10 −2 time scales within oxycline and bottom waters. Our data suggest an important role for NH 3 oxidation in alkaline, saline lakes since the process converts volatile NH 3 to soluble NO 2 − , thereby reducing loss via lake‐atmosphere exchange and maintaining nitrogen in a form that is readily available to phyto‐plankton.

Limnology and Oceanography↗
USGS2015

Thermokarst lake methanogenesis along a complete talik profile

Thermokarst (thaw) lakes emit methane (CH 4 ) to the atmosphere formed from thawed permafrost organic matter (OM), but the relative magnitude of CH 4 production in surface lake sediments vs. deeper thawed permafrost horizons is not well understood. We assessed anaerobic CH 4 production potentials from various depths along a 590 cm long lake sediment core that captured the entire sediment package of the talik (thaw bulb) beneath the center of an interior Alaska thermokarst lake, Vault Lake, and the top 40 cm of thawing permafrost beneath the talik. We also studied the adjacent Vault Creek permafrost tunnel that extends through ice-rich yedoma permafrost soils surrounding the lake and into underlying gravel. Our results showed CH 4 production potentials were highest in the organic-rich surface lake sediments, which were 151 cm thick (mean ± SD: 5.95 ± 1.67 μg C–CH 4 g dw −1 d −1 ; 125.9 ± 36.2 μg C–CH 4 g C −1 org d −1 ). High CH 4 production potentials were also observed in recently thawed permafrost (1.18 ± 0.61 μg C–CH 4 g dw −1 d −1 ; 59.60± 51.5 μg C–CH 4 g C −1 org d −1 ) at the bottom of the talik, but the narrow thicknesses (43 cm) of this horizon limited its overall contribution to total sediment column CH 4 production in the core. Lower rates of CH 4 production were observed in sediment horizons representing permafrost that has been thawing in the talik for a longer period of time. No CH 4 production was observed in samples obtained from the permafrost tunnel, a non-lake environment. Our findings imply that CH 4 production is highly variable in thermokarst lake systems and that both modern OM supplied to surface sediments and ancient OM supplied to both surface and deep lake sediments by in situ thaw and shore erosion of yedoma permafrost are important to lake CH 4 production.

Biogeosciences↗
USGS2016

Methane and sulfate dynamics in sediments from mangrove-dominated tropical coastal lagoons, Yucatan, Mexico

Porewater profiles in sediment cores from mangrove-dominated coastal lagoons (Celestún and Chelem) on the Yucatán Peninsula, Mexico, reveal the widespread coexistence of dissolved methane and sulfate. This observation is interesting since dissolved methane in porewaters is typically oxidized anaerobically by sulfate. To explain the observations we used a numerical transport-reaction model that was constrained by the field observations. The model suggests that methane in the upper sediments is produced in the sulfate reduction zone at rates ranging between 0.012 and 31 mmol m −2 d − 1 , concurrent with sulfate reduction rates between 1.1 and 24 mmol SO 4 2− m −2 d −1 . These processes are supported by high organic matter content in the sediment and the use of non-competitive substrates by methanogenic microorganisms. Indeed sediment slurry incubation experiments show that non-competitive substrates such as trimethylamine (TMA) and methanol can be utilized for microbial methanogenesis at the study sites. The model also indicates that a significant fraction of methane is transported to the sulfate reduction zone from deeper zones within the sedimentary column by rising bubbles and gas dissolution. The shallow depths of methane production and the fast rising methane gas bubbles reduce the likelihood for oxidation, thereby allowing a large fraction of the methane formed in the sediments to escape to the overlying water column.

Yucatan↗
USGS2026

Proposing sources for discrete groundwater discharges to patterned pools in three regional raised northern peat bogs

Raised northern peat bogs are generally assumed to be entirely precipitation-fed (ombrogenous), suggesting they are void of groundwater (minerogenous) inflow from underlying sediments. Patterned pools in raised bogs have often been attributed to surficial flow filling depressions along the peat surface that produces subtle differences in peat pore-water chemistry. However, we present evidence that certain patterned pools may be partially fed by localized upwelling of minerogenous groundwater from underlying glacial sediments in three northern peat bogs of Maine, USA. Underlying permeable glacial deposits, embedded in hydraulically confining glacio-marine clay deposits, were delineated using ground-penetrating radar and transient electromagnetic surveys. Paired point measurements of temperature and specific conductance (SpC) were surveyed around pools, and statistical relationships indicative of groundwater upwelling were established. Uncrewed aerial systems (UAS) thermal infrared (TIR) mapping was conducted, augmented by handheld TIR imaging, to examine characteristic groundwater temperatures in cold and warm seasons across pool surfaces. Surface water samples were acquired to assess the relationship between SpC / temperature signals and elevated iron and manganese concentrations that could be indicative of glacial aquifer sources. The combined datasets present evidence for localized upwelling in pools underlain by glacial structures, and the possibility of minerogenous groundwater contributions. Upwelling through the peat matrix is possibly partially facilitated by macropore, “peat pipe” features that serve as preferential flowpaths of varying lengths to the surface. Such upwelling could drive a positive feedback loop where elevated concentrations of ionic constituents repeatedly dilate the peat matrix and/or terminal electron acceptors enhance anaerobic respiration and microbial activity, accelerating the humification of peat around patterned pools and potentially magnifying carbon loss.

Maine↗
USGS1998

The inhibition of Clostridium botulinum type C by other bacteria in wetland sediments

Bacteria with inhibitory activity against Clostridium botulinum type C were isolated from 32% of sediment samples ( n = 1600) collected from 10 marshes in a northern California wetland over a 12 mo period. Aerobic and anaerobic bacteria with inhibitory activity were isolated from 12% and 23% of the samples, respectively. Bacteria with inhibitory activity were isolated from all 10 study sites and throughout the year. This study demonstrates that bacteria with inhibitory activity against C. botulinum type C occur naturally in wetland sediments.

California↗
USGS1986

Forested wetlands of the Southeast: Review of major characteristics and role in maintaining water quality

Forested wetlands occupying floodplains of major rivers in the Southeast are highly productive and diverse ecological systems. The wetlands are produced and maintained by fluvial processes and unique hydrologic regimes consisting of periodic flooding and subsequent drydown. Fluctuations in soil chemistry and biology resulting from this flooding and drydown provide a broad range of environmental conditions that are important in determining the role of forested wetlands in maintaining and improving water quality. The periodic shift between aerobic and anaerobic conditions in floodplain soils in response to flooding facilitates the assimilation of nutrients and organic matter, hastens the degradation of persistent pesticides, and decreases the bioavailability of heavy metals.

Resource Publication↗
USGS1989

Zinc movement in sewage-sludge-treated soils as influenced by soil properties, irrigation water quality, and soil moisture level

A soil column study was conducted to assess the movement of Zn in sewage-sludge-amended soils. Varables investigated were soil properties, irrigation water quality, and soil moisture level. Bulk samples of the surface layer of six soil series were packed into columns, 10.2 cm in diameter and 110 cm in length. An anaerobically digested municipal sewage sludge was incorporated into the top 20 cm of each column at a rate of 300 mg ha-1. The columns were maintained at moisture levels of saturation and unsaturation and were leached with two waters of different quality. At the termination of leaching, the columns were cut open and the soil was sectioned and analyzed. Zinc movement was evaluated by mass balance accounting and correlation and regression analysis. Zinc movement in the unsaturated columns ranged from 3 to 30 cm, with a mean of 10 cm. The difference in irrigation water quality did not have an effect on Zn movement. Most of the Zn applied to the unsaturated columns remained in the sludge-amended soil layer (96.1 to 99.6%, with a mean of 98.1%). The major portion of Zn leached from the sludge-amended soil layer accumulated in the 0- to 3-cm depth (35.7 to 100%, with a mean of 73.6%). The mean final soil pH values decreased in the order: saturated columns = sludge-amended soil layer > untreated soils > unsaturated columns. Total Zn leached from the sludge-amended soil layer was correlated negatively at P = 0.001 with final pH (r = -0.85). Depth of Zn movement was correlated negatively at P = 0.001 with final pH (r = -0.91). Multiple linear regression analysis showed that the final pH accounted for 72% of the variation in the total amounts of Zn leached from the sludge-amended soil layer of the unsaturated columns and accounted for 82% of the variation in the depth of Zn movement among the unsaturated columns. A significant correlation was not found between Zn and organic carbon in soil solutions, but a negative correlation significant at P = 0.001 was found between pH and Zn (r = -0.61).

Soil Science↗
USGS1991

Assessing the effects of microbial metabolism and metabolities on reservoir pore structure

The effect of microbial treatment on pore structure of sandstone and carbonatereservoirs was determined. Understanding how different bacterial strains and their metabolic bioproducts affect reservoir pore structure will permit the prudent application of microorganisms for enhanced oil recovery. The microbial strains tested included Clostridium acetobutylicum, a polymer-producing Bacillus strain, and an unidentified halophilic anaerobe that mainly produced acids and gases. Electrical conductivity, absolute permeability, porosity and centrifuge capillary pressure were used to examine rock pore structures. Modifications of the pore structure observed in the laboratory cores included pore enlargement due to acid dissolution of carbonates and poare throat reduction due to biomass plugging. This paper shows that careful selection of microbes based on proper understanding of the reservoir petrophysical characteristics is necessary for applications of microbially enhanced oil recovery. These methods and results can be useful to field operators and laboratory researchers involved in design and screening of reservoirs for MEOR. The methods are also applicable in evaluation of formation damage caused by drilling, injection or completion fluids or stimulation caused by acids.

Conference Paper↗