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Forward and inverse gravity modeling is carried out on a suite of reservoir simulations of a proposed water injection in the Prudhoe Bay reservoir, Alaska. A novel surveillance technique is developed in which surface gravity observations are used to monitor the progress of a gas cap waterflood in the reservoir at 8200-ft (2500-m) depth. This cost‐effective method requires that high‐precision gravity surveys be repeated over periods of years. Differences in the gravity field with time reflect changes in the reservoir fluid densities. Preliminary field tests at Prudhoe Bay indicates survey accuracy of 5–10 μGal can be achieved for gravity data using a modified Lacoste & Romberg “G” type meter or Scintrex CG-3M combined with the NAVSTAR Global Positioning System (GPS). Forward gravity modeling predicts variations in surface measurements of 100 μGal after 5 years of water injection, and 180–250 μGal after 15 years. We use a constrained least‐squares method to invert synthetic gravity data for subsurface density distributions. The modeling procedure has been formulated and coded to allow testing of the models for sensitivity to gravity sampling patterns, noise types, and various constraints on model parameters such as density, total mass, and moment of inertia. Horizontal‐feature resolution of the waterflood is about 5000 ft (1520 m) for constrained inverse models from synthetic gravity with 5 μGal standard deviation (SD) noise. The inversion method can account for total mass of injected water to within a few percent. Worst‐case scenarios result from inversion of gravity data which are contaminated by high levels (greater than 10–15 μGal SD) of spatially correlated noise, in which case the total mass estimate from inverse models may over or underestimate the mass by 10–20%. The results of the modeling indicate that inversion of time‐lapse gravity data is a viable technique for the monitoring of reservoir gas cap waterfloods.

Anaerobic transformations of 1,1,1-trichloroethane (TCA), 1,1-dichloroethane (DCA), and chloroethane (CA) were studied with sludge from a lab-scale, municipal wastewater sludge digester. TCA was biologically transformed to DCA and CA and further to ethane by reductive dechlorination. TCA was also converted to acetic acid and 1,1-dichloroethene (11DCE) by cell-free extract. 11DCE was further biologically converted to ethene. This pathway was confirmed by transformation tests of TCA, DCA and CA, by tests with cell-free extract, and by chloride release during TCA degradation. With cell-free extract, acetic acid accounted for approximately 90% of the TCA transformed; tests with live cells indicate that the fraction of TCA transformed by this pathway decreased with lower biomass. The dechlorination of DCA to CA and CA to ethane was not stoichiometric. A high rate of TCA removal was observed under the experimental conditions. The results indicate that removal of TCA in anaerobic digestion should be complete, but DCA and CA could persist in a normally operating digester.

A 2,3,4,6-tetrachlorophenol- (TeCP-) and pentachlorophenol- (PCP-) degrading microbial culture was enriched from supernatant of municipal activated sludge using laboratory-scale continuous-flow fluidized-bed reactors (FBRs). Effluent concentrations of less than 10 μg/L were obtained within 12 days for TeCP and within 24 days for PCP at influent concentrations of 22 and 3.1 mg/L of TeCP and PCP, respectively, and at a 5-hour hydraulic retention time (HRT). Shorter HRTs at similar chlorophenol loading rates resulted in longer start-up times. Biodegradation of PCP was always more sensitive to increases in loading rate or decreases in HRT than was TeCP degradation. With TeCP and PCP loading rates of 100 and 15 mg/L. d, respectively, effluent TeCP concentrations of less than 10 μg/L were achieved even at a 3.7-minute HRT, while PCP removal efficiency started to decrease at HRTs of less than 38 minutes. During shock loading tests at a 14-minute HRT, more than 99.9% TeCP degradation was obtained at a 2 200-mg/L.d loading rate, while PCP degradation remained at 73% at a loading rate of 314 mg/L.d. In batch degradation tests in the FBR, TeCP degradation followed Michaelis-Menten kinetics at initial concentrations of less than 31 mg/L, with a minimum specific substrate rate (q max ) of 0.59 mg TeCP/mg volatile solids (VS).d and K s (half-saturation constant) of 0.41 mg/L. Pentachlorophenol degradation was modeled using the modified Haldane equation with the following kinetic constants: q max = 0.066 mg PCP/mg VS.d, K s = 1.1 mg/L, K i (inhibition constant) = 1.7 mg/L, and n (constant) = 3. The results showed that FBR rapidly enriches chlorophenol-degrading cultures able to produce good-quality effluents. After start-up, FBRs can be operated over a wide range of loading rates for bioremediation of chlorophenol-contaminated water.

Land gravity meters have traditionally been analog, with readings carried out and transcribed manually. The precision (theoretically 10–50 μGal) and the observation rate are very dependent on the skill of the observer. However, the advent of digital recording meters, now offered by several commercial firms, has automated much of the work. As a result, land gravity surveying is both faster and more accurate than in the past and can now be applied to problems where it previously was of little help.

Pharmaceutical and personal care products (PPCPs) discharged with wastewater treatment effluents are a surface water quality concern. PPCPs are partially removed during wastewater treatment and biological transformation is an important removal mechanism. To investigate the potential for enhanced PPCP removal using bioaugmentation, bacteria were previously isolated from activated sludge capable of degrading PPCPs to ng/L concentrations. This study examined the degradation kinetics of triclosan and bisphenol A by five of these bacteria, both in pure culture and when augmented to activated sludge. Sorption coefficients were determined to account for the influence of partitioning during bioremoval. When the bacteria were added to activated sludge, degradation increased. Experimentally determined kinetic parameters were used to model a full-scale continuous treatment process, showing that low biomass could achieve reduced effluent PPCP concentrations. These results demonstrated that bioaugmentation may improve PPCP removal using established wastewater infrastructure under conditions of high solids partitioning.

A methanogenic fluidized bed reactor (FBR) fed with lactate and tetrachloroethene (PCE) was operated for 14 months to study the effect of electron donor and PCE loading on chloroethene dechlorination rates. Lactate was fed continu ously at 200 mg/L (2.2 mmol/L), and the influent PCE feed concentration was increased stepwise from 3.5 to 160 μmol/L. Vinyl chloride (VC) and ethene accounted for 80% and 20%, respectively, of the PCE dechlorination. Batch tests with various electron donors showed that H2, propionate, and lactate supported dechlorination of PCE, trichloroethene (TCE), cis-dichloroethene (c-DCE), and VC, whereas no dechlorination was observed with acetate or in the absence of an electron donor. Different short-term steady H2 concentrations were obtained by adjusting the FBR influent lactate feed concentration, and the effect of H2 concentra tion on the rate of chloroethene dechlorination was determined. Dechlorination rates for PCE, TCE, c-DCE, and VC showed a Michaelis−Menten relationship with ...

Ethylenediamine tetraacetic acid (EDTA) and diethylenetriamine pentaacetic acid (DTPA) are synthetic chelating agents that form stable complexes with most metals and are used in a variety of industrial applications. They are increasingly used with peroxide and ozone bleaching of wood pulp to sequester iron and manganese. These chelates have been widely reported to either resist degradation or undergo slow biodegradation. EDTA and DTPA have few known environmental impacts in receiving waters. A study was conducted to assess the biodegradability of EDTA and DTPA and to determine if these compounds could be transformed in conventional effluent treatment processes. Four dissimilar inocula were used in batch and continuous aerobic tests using a variety of enrichment techniques. Selection pressure was applied to bacterial populations by providing EDTA and DTPA as sole carbon sources. Additionally, experiments were conducted using degraders of chemically similar compounds nitrilotriacetic acid and triethanolamine. In all experiments, the results showed that neither EDTA or DTPA are biodegraded under aerobic conditions.

In most gravity surveys, gravity and position data are usually collected, stored, and processed separately. They are either recorded manually in a field notebook or in the memories of the instruments with subsequent data entry or download to a computer for processing. However, this has several disadvantages; in particular, most instrument interfaces are too crude to continuously monitor the measurement and thus detect problems in the field, such as meter malfunctions. This means that the separate recording of the gravity and position data is prone to problems such as station misidentification, transcription errors, or even missing records.

Barrier islands in the Gulf of Mexico are affected by hurricanes, oil spills, and changing sedimentation patterns. Barrier island environments influence effective remediation of contamination, future development, and environmental management. Barrierisland unconfined aquifer systems are susceptible to storm flooding, changes in sea level, coastal erosion, and contamination events. These aquifers supply water for those living on the islands and wildlife. Barrier islands are vulnerable to pollution by anthropogenic incidents (e.g., the Deep Water Horizon event, barge spills in the Intercoastal Waterway, and pipeline ruptures) and natural events (e.g., changing salinities in the landward lagoons caused precipitation, evaporation, and river discharge). Barrier islands respond by: 1) changing erosional and depositional patterns; 2) damage/destruction from increased storm vulnerability; 3) salt-water intrusion; and 4) drowning of wetlands. The extent, magnitude, and response rate depend upon and create heterogeneity in hydraulic conductivity and porosity the internal architecture of the aquifer systems. Barrier island stratigraphy varies rapidly in both cross island and beach parallel directions. The Gulf coast islands are only a few thousand years old with only 10 20 m thickness above the Pleistocene Beaumont Formation. Both the Holocene and Pleistocene hydrostratigraphy need to be defined. The 3-D geometry of barrier island depositional systems and their property impacts the, understanding of sea-level change and pollution events. Most current models neglect heterogeneity by assuming over-simplified parameter distributions that cannot capture the dynamics of aquifer flow and solute transport.

Aerobic polycyclic aromatic hydrocarbon (PAH) degrading bacteria were enriched from creosote contaminated marine sediments (Puget Sound, Washington, USA) using a continuous-flow fluidized-bed reactor. Artificial seawater media and a mixture of seven 2 to 3-ring PAHs were used as enrichment substrates. The biodegradability of PAH mixtures by the enrichment was determined in batch vial assays. The tested PAH mixtures included alkyl substituted naphthalenes, phenanthrene, anthracene, fluoranthene, and pyrene. Co-occurring PAHs significantly affected the degradation rates of individual compounds. Degradation was generally slower in mixtures than with individual compounds indicating competition. Degradation of some recalcitrant PAHs, on the other hand, was enhanced in mixtures. Phenanthrene degraded rapidly but pyrene degradation was insignificant when present alone. In pyrene-phenanthrene mixtures, pyrene was nearly completely removed indicating enzyme induction or cometabolism.

Natural organic matter (NOM) profoundly affected the corrosion of copper in a moderately alkaline synthetic water. It decreased the rate of corrosion, increased the rate of copper leaching, and dispersed crystalline inorganic corrosion products. The interaction of NOM Whith corrosion products was modeled using separate phases of malachite and cuprous oxide. The authors concluded that NOM promotes the formation of pits in a certain narrow range of concentrations (0.1-0.2 mg/L in laboratory tests) and suppresses this type of corrosion at higher dosages. At low DOC concentrations, the main interaction between NOM and the surfaces of corroding metal and corrosion products is adsorption. The influence of NOM on corrosion of metals in real distribution systems must be studied in relation to long periods of surface aging, flow rate, concentration and type of oxidants, pH, and alkalinity.

An extension of the boundary integral method for SH waves is given for transversely isotropic media. The accuracy of the method is demonstrated for a simple flat interface problem by comparison to the Cagniard-de Hoop solution. The method is further demonstrated for a case with interface topography for both surface and vertical seismic profiles. The new method is found to be both accurate and effective.

Ammonia-oxidizing bacteria from marine sediment (Puget Sound, WA) were selectively enriched in a fluidized-bed system (FBS). The enrichment culture converted ammonia stoichiometrically to nitrite. During continuous feed, steady-state ammonia removal was 0.20 mmol/l/h. In a batch fed FBS, at an initial 3.4 mM ammonia concentration, ammonia removal rate was 12 mmol/h/g protein. The enrichment culture degraded cis-1,2-dichloroethene, trichloroethene, methylene chloride and chloroform. Allylthiourea, a specific ammonia monooxygenase inhibitor, prevented degradation suggesting catalysis by nitrifiers. Other compounds, including 1,1,1-trichloroethane, 4-mono-, 2,4,6-trichloro-, 2,3,4,6-tetrachloro-, and pentachlorophenol were not removed. Immunofluorescence assay and polymerase chain reaction (PCR) methods showed that the enrichment culture contained a marine Nitrosomonas species. Extracted DNA from the culture was amplified using 16s rRNA PCR primers designed for the autotrophic ammonium oxidizers of the β-subgroup including marine Nitrosomonas spp., but not with primers designed for Nitrosococcus oceanus. Transmission electron micrographs of the enrichment culture showed bacteria with internal membranes that were similar to those of Nitrosomonas.

Abiotic and biotic transformations of 1,1,2,2-tetrachloroethane (TeCA) under methanogenic conditions were studied. TeCA degradation started without lag with municipal digester sludge. 1,1,2-Trichloroethane (1,1,2-TCA), trans-1,2-dichloroethene (tDCE), and cis-1,2-dichloroethene (cDCE) were products of biotic transformation, while trichloroethene (TCE) resulted from abiotic degradation. TCE was further transformed to cDCE, vinyl chloride (VC), and ethene. Ethene, VC, and tDCE were the persistent products of TeCA transformations. With the same municipal digester sludge culture, 1,1,2-TCA was removed and converted to 1,2-dichloroethane (1,2-DCA) and VC. 1,2-DCA partially degraded, resulting in chloroethane and ethene formation. Reductive dechlorination, dichloroelimination, and dehydrochlorination simultaneously took place during the degradation of TeCA. Dichloroelimination and dehydrochlorination played important roles in the removal of TeCA and 1,1,2-TCA under methanogenic conditions.

This study examined effects of varying levels of anions (chloride and sulfate) and natural organic matter (NOM) on iron release from and accumulation of inorganic contaminants in corrosion scales formed on iron coupons exposed to drinking water. Changes of concentrations of sulfate and chloride were observed to affect iron release and, in lesser extent, the retention of representative inorganic contaminants (vanadium, chromium, nickel, copper, zinc, arsenic, cadmium, lead and uranium); but, effects of NOM were more pronounced. DOC concentration of 1 mg/L caused iron release to increase, with average soluble and total iron concentrations being four and two times, respectively, higher than those in the absence of NOM. In the presence of NOM, the retention of inorganic contaminants by corrosion scales was reduced. This was especially prominent for lead, vanadium, chromium and copper whose retention by the scales decreased from >80% in the absence of NOM to

The effect of orthophosphate addition (1 mg/L as P) on copper and lead-tin solder corrosion was monitored using an experimental coupon exposure apparatus with measurement by standing water metals analysis, gravimetric analysis, direct galvanic current metering, and potentiodynamic scan analysis. Orthophosphate addition appeared to have a significant effect on lead-tin solder corrosion although the results of each analysis differed in magnitude. The effect of orthophosphate addition on copper corrosion was less clear with gravimetric analysis showing a significant effect, whereas metals release analysis showed only a slight effect.

A detailed treatability study investigating metals removal from leachates collected from a sanitary landfill is presented. Experiments investigated treatment of raw leachate from younger and older zones of the landfill and of a mixture of the two leachates (representing an average leachate from the landfill). The metal concentrations and COD in leachate from the older area were approximately one order of magnitude greater than in leachate from the active area. The leachates contained significant quantities of reduced iron and manganese that, upon aeration and base addition, were precipitated and served as sorbents for trace metals that were present at much lower concentrations. Most trace metals in the younger zone leachate and in the leachate mixture were removed by adjusting solution pH to 9.0, but in leachates collected from the older landfill area, even raising the pH to 11.0 did not remove all the trace metals efficiently. Various options for treating a blend of leachate from the older and younger areas (20%:80% by volume) were evaluated. One of the key design decisions was whether to aerate the leachate prior to pH adjustment. Trace metals could be removed efficiently from the leachate with or without aeration. Benefits of aeration include increased formation of iron oxide adsorbent and a significant reduction in the amount of base required to raise the pH, since aeration strips large amounts of CO2 from the leachates. Drawbacks include decreased sludge settleability and the cost of the aeration process itself. The settleability of the aerated sludge could be increased 5–10 fold by the addition of anionic polymer. Sludge produced was not toxic as determined by TCLP. Trade-offs implicit in these results are addressed both experimentally and theoretically.

An aerobic, continuous-flow fluidized-bed reactor was established with inoculum from activated sludge, and fed a mixture of 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP) and pentachlorophenol (PCP) as the sole sources of carbon and energy for 2 years. Experiments with the enrichment were performed with material from the reactor. Later, degradation experiments were completed using pure cultures of bacteria that were isolated from suspended samples of the carrier biofilm. In batch-bottle bioassays, the reactor enrichment degraded PCP, TeCP and TCP both in mineral salts (MS) and tryptone-yeast extract-glucose (TGY) media. ortho-Methoxylated chlorophenols including 4,5-dichloroguaiacol (4,5-DCG), tetrachloroguaiacol (TeCG) and trichlorosyringol (TCS) resisted biodegradation by the enrichment both in MS and TGY media, whereas 5,6-dichlorovanillin (5,6-DCV) was readily transformed to an unidentified metabolite. Experiments with 14C labeled chlorophenols showed mineralization of 2,4-dichlorophenol (DCP) and 2,3,5-TCP to 14CO2 by the enrichment. Material from the suspended biofilm after continuous chlorophenol feeding for 2 years was inoculated onto TGY-agar plates, and showed predominantly two colony, types accounting for over 99% of the total colony counts. The two colony types, were equal in abundance. Six Gram-negative, oxidase- and catalase-positive, non-fermentative small rods were isolated in TGY agar media supplemented with 10 mg/l of TeCP or PCP. All isolates formed colonies in TGY plus 150 mg/l of PCP. The isolates degraded TCP and TeCP but not PCP. In mixtures of isolated bacteria the rates of chlorophenol degradation were similar to those observed with individual isolates. Three isolates were identified as Pseudomonas saccharophila and three were an unidentified species of Pseudomonas.

This study examined effects of blending desalinated water with conventionally treated surface water on iron corrosion and release from corroding metal surfaces and pre-existing scales exposed to waters having varying fractions of desalinated water, alkalinities, pH values and orthophosphate levels. The presence of desalinated water resulted in markedly decreased 0.45 μm-filtered soluble iron concentrations. However, higher fractions of desalinated water in the blends were also associated with more fragile corroding surfaces, lower retention of iron oxidation products and release of larger iron particles in the bulk water. SEM, XRD and XANES data showed that in surface water, a dense layer of amorphous ferrihydrite phase predominated in the corrosion products. More crystalline surface phases developed in the presence of desalinated water. These solid phases transformed from goethite to lepidocrocite with increased fraction of desalinated water. These effects are likely to result from a combination of chemical parameters, notably variations of the concentrations of natural organic matter, calcium, chloride and sulfate when desalinated and conventionally treated waters are blended.

The northwestern margin of the Espanola basin, part of the Rio Grande rift in northern New Mexico, is characterized by a zone >17 km wide of oblique-slip faults that offset upper Paleozoic and Mesozoic strata of the eastern Colorado Plateau from Eocene and younger sedimentary rocks of the rift. Along this margin, a reasonably complete section of pre- and synrift Tertiary sediments is exposed. Combined interpretations of seismic reflection, seismic refraction, gravity, and geologic data acquired along a profile perpendicular to this boundary define the geometry of faulting, possible rotation of sedimentary units, and stratigraphy of rift fill. Vertical separation on the westernmost major fault, assumed to be the bounding fault between the rift and the Colorado Plateau, is Although Tertiary units are progressively faulted downward toward the axis of the rift, depth to inferred Precambrian crystalline rocks becomes shallower and the stratigraphic thickness of the intervening Paleozoic and Mesozoic units decreases toward the axis. We interpret pinching out of these units toward the east as erosional thinning on the western flanks of the Laramide-age Sangre de Cristo/Brazos geanticline, which underlay much of the present rift basin. Imprecise age constraints suggest that faulting of the rift margin began 10-7 Ma, but was not active after 7 Ma. Extension was apparently transferred to the Embudo fault zone, which remained active until at least 2.5 Ma and possibly into Quaternary time. The Embudo transfer zone effectively decoupled the Abiquiu embayment from the main Espanola basin. Thus the boundary at Abiquiu preserves an early stage in the formation of the rift boundary. The shift in activity may have resulted from a change in regional stress field, or from increasing magnitude of strain, or both. The change in locus of extension reflects a narrowing of rift basins through time and an integration of main bounding structures between adjacent basins. Although we are uncertain whether the Abiquiu region, which uniquely preserves an early stage of deformation, is representative of other areas of continental extension, our results indicate that the initial formation of rift basins may occur as high-angle, planar normal faults distributed over a broad zone. No evidence from seismic data or from rotation of beds exists to indicate that faults become listric with depth, which is compatible with the small amount of extension (3.5%) inferred at this boundary.

Reductive dechlorination of 2,4,6-trichlorophenol (2,4,6-TCP) to 2,4-dichlorophenol and to 4-chlorophenol is found in mixed methanogenic cultures enriched from municipal sludge digesters. In this study, electron donors, including hydrogen, acetate and fructose, were effectively converted to methane and supported this dehalogenation in periods of 2 to 4 weeks. When bromoethanesulfonic acid (BESA) and vancomycin were used, dechlorination and methanogenesis were strongly affected. With hydrogen, BESA nearly completely inhibited lithotrophic methanogenesis; acetate accumulated from lithotrophic acetogenesis and dehalogenation proceeded. Vancomycin, however, inhibited dehalogenation while methanogenesis was not affected. With acetate, BESA completely inhibited methanogenesis and substantially slowed dehalogenation; the acetate was not used. Vancomycin, on the other hand, stopped dehalogenation, while methanogenesis proceeded. With fructose plus titanium citrate, BESA inhibited methanogenesis; acetate and propionate accumulated, and dehalogenation proceeded; vancomycin inhibited dehalogenation. Autoclaved controls had neither dehalogenation nor methanogenesis. These results point to biological dehalogenation by eubacteria, rather than methanogens. In the case of acetate, where both inhibitors effectively stopped dehalogenation, they also indicate a syntrophic relation between acetoclastic methanogens and the dehalogenating bacteria. In further studies with 2,4,6-TCP concentrations ranging up to 160 mg/l there was increasing toxicity to methanogens and changes in accumulation of fatty acids, but dehalogenation persisted at the highest concentrations.

Biotransformations of several chlorinated phenols were studied in aerobic cultures enriched on glucose, methane, phenol and toluene and acclimated to 16 chlorinated compounds. The toluene enrichment culture degraded pentachlorophenol (PCP) and 2,4,6-trichlorophenol (2,4,6-TCP), while the cultures enriched on glucose, methane or phenol showed little or no activity. The phenol and toluene enriched cultures rapidly degraded 2,4-dichlorophenol (2,4-DCP) but not 2,6-DCP or 2,4,5-TCP. Degradation of chlorophenols by the toluene enriched culture did not occur endogenously but continued when wnother carbon source, acetate, was introduced. Degradation of chlorophenols proceeded after starvation and in the presence of chloramphenicol, suggesting constitutive enzymatic activity. The initial steps of PCP degradation by the toluene enriched culture involved dechlorination and hydroxylation of an ortho carbon to form tetrachlorocatechol. Tetrachloroguaiacol was identified as a minor, dead-end metabolite of PCP degradation by the toluene enriched culture.

Some current theories of copper pitting are contradicted by practical experience. Although it has been theorized that chloride initiates copper pitting attack, simple experiments show that the presence of chloride ion actually tends to decrease the likelihood that pitting will occur. In contrast, sulfate plays no role in pitting theory, yet sulfate has consistently demonstrated a propensity to initiate and propagate copper pitting. New theories are required to reconcile pitting theory and practical observation in order to allow the rational mitigation of copper pitting problems. In addition, the presence of natural organic matter (NOM) in water supplies prevents or inhibits certain copper corrosion problems. As a result, recent efforts to remove NOM as a means of controlling disinfection by-products may lead to increased copper corrosion problems.

Revision of lithological logs for boreholes penetrating the volcanic center at Pahute Mesa, Nevada, has led to a thorough review of the volcanic stratigraphy and geologic structure. We have combined this review with a compilation of old and newly acquired gravity and seismic travel time data, producing a unified interpretation along a northwest to southeast profile. The analysis supports a new interpretation of the Silent Canyon caldera complex. The caldera is found to be more asymmetric than previously suggested, with the southeastern boundary formed by linear, high-angle normal faults and a more gently sloping northwestern boundary. The total thickness of volcanic units within the caldera complex does not appear to exceed 5 km. The shallow structure at Pahute Mesa could have a profound effect on the seismic response for regional and teleseismic signals from this nuclear test site. The Silent Canyon caldera complex is actually a set of nested calderas first filled by thick (>1 km) postcaldera lavas and subsequently buried by outflow sheets of the Timber Mountain caldera to the south. Thick, postcaldera lavas filled a half-graben structure formed west of the West Greeley fault, dropping the tops of the youngest caldera-forming units to depths in excess of 2 km. Therefore the western boundary of the caldera complex is poorly defined. East of the West Greeley fault, two overlapping calderas are defined, and stratigraphic data suggest the presence of even older calderas. The youngest caldera, the calc-alkaline Area 20 caldera, is well defined from drill hole data. The Area 20 caldera overlaps the 13.6 Ma peralkaline Grouse Canyon caldera, which is less well defined, but apparently collapsed in trap-door style along the Almendro fault. For both these calderas, collapse continued after the main caldera-forming eruption, concurrent with the accumulation of thick (>1 km) lavas within the peripheral collapse zones. The geophysical interpretation indicates that the major structural boundary of the caldera complex corresponds to the NNE trending Scrugham Peak and Almendro faults, which offset the pre-Tertiary contact more than 1 km but have less than 200 m offset in rocks of 11 Ma age. Drill hole data show that offsets along these faults increase systematically within older (up to 15 Ma) units, which are commonly rotated eastward in a style similar to units at the surface. Abrupt changes in the subsurface thickness of the caldera-forming units occur across the faults, indicating that these linear features served as caldera boundaries.

A two-year study has focused on AOX removal from bleaching wastewaters in anaerobic and aerobic biological treatment, using bench scale bioreactors operated in parallel and in series. Significantly higher removals have been found in anaerobic than in aerobic treatment. Earlier work with dilute kraft bleaching wastes has been extended in additional laboratory tests and at a nearby kraft mill. 50-75% fractions of bleaching wastes were treated. Toxicity in the anaerobic process was encountered at 85% bleach waste fractions. Total AOX removal experienced in aerobic treatment is 30-35%, in anaerobic treatment 40-45%, and in an anaerobic/aerobic sequence 50-55%. Percentage removals were not sensitive to the fraction of bleaching wastewater. Several process modifications were attempted to try to obtain higher removals with only marginal success. Studies at a kraft mill confirmed the AOX removals that had been found in lab studies. AOX removal occurs by several mechanisms. There is a very significant chemical or abiotic degradation that occurs after neutralization, perhaps enhanced by reductants or other inorganic salts. Biological processes are much more significant in anaerobic than in aerobic treatment. Anaerobic reductive dehalogenation affects specific chlorinated compounds and catalyzed AOX degradation is facilitated by reduced coenzymes that are produced by bacteria. Removal by sorption or insolubilization is relatively minor in aerobic and anaerobic processes.

Biotransformations and treatment of several chlorinated, hydroxylated and methoxylated monoaromatic compounds were studied in batch bottle bioassays and continuous-flow fluidized-bed reactors. With the aerobic enrichment, polychlorinated phenols were biodegraded with simultaneous release of inorganic chloride in amounts equal to mineralization stoichiometrics. Aerobic removal of 4,5-dichlorocatechol and 4,5- dichlorovanillin were associated with the release of inorganic chlorine. The aerobic enrichment showed no activity against mono- or di-O-methylated phenols. With the anaerobic enrichment, reductive transformations of these compounds were observed. These transformations included reductive dechlorinations, de-O-methylations and dehydroxylations. High-rate operation of an aerobic fluidized-bed reactor resulted in over 99.7% biodégradation of polychlorophenols. In the anaerobic fluidized-bed reactor, over 95% removal of chlorophenols with no apparent accumulation of lower chlorinated phenols indicated complete dechlorination.

The formation of lead dioxide PbO(2), an important corrosion product in drinking water distribution systems with lead-bearing plumbing materials, has been hypothesized to involve Pb(III) intermediates, but their nature and formation mechanisms remain unexplored. This study employed the electrochemical (EC) method of rotating ring disk electrode (RRDE) and quantum chemical (QC) simulations to examine the generation of intermediates produced during the oxidation of Pb(II) to PbO(2). RRDE data demonstrate that PbO(2) deposition and reduction involves at least two intermediates. One of them is a soluble Pb(III) species that undergoes further transformations to yield immobilized PbO(2) nanoparticles. The formation of this intermediate in EC system is mediated by hydroxyl radicals (OH(•)), as was evidenced by the suppression of intermediates formation in the presence of the OH(•) scavenger para-chlorobenzoic acid. QC simulations confirmed that the oxidation of Pb(II) by OH(•) proceeds via Pb(III) species. These results show that Pb(III) intermediates play an important role in the reactions determining transitions between Pb(II) and Pb(IV) species and could impact lead release in drinking water.

Reductive dechlorination of polychlorinated biphenyls (PCBs) was studied by methanogenic and sulfate-amended laboratory cultures enriched from marine sediments (Puget Sound, WA) in sea-salts media. One sulfate-amended and one methanogenic culture were incubated at a hydraulic retention time of 50 days and fed chitin, sodium benzoate, sodium acetate, and a mixture of four PCB congeners (2,3,3',5-tetrachlorobiphenyl, 2,2',4,5,6'-pentachlorobiphenyl, 2,3',4,5',6-pentachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl), slowly increasing the concentrations to 6-9 mg/L over 11 months. In these cultures, no dehalogenation of the four congeners was observed. Two other cultures were batch fed Aroclor 1254 at a concentration of 100 mg/L; chitin was used as the PCB carrier and the sole carbon and electron source

San Marcos Pueblo, archaeological site LA 98, was occupied in the 13th century and abandoned after 1680. This was a large community that conducted extensive trade based on local mineral resources. The Summer of Applied Geophysical Experience (SAGE) Field Course has conducted investigations pointing to unique groundwater access as a motivating factor in the pueblo settlement. The Quaternary stratigraphy of the site has been reveled by near-surface seismic refraction profiling. The specific hydrogeologic conditions leading to the reliability of San Marcos Spring are the presence of the Ancha formation, its basal juxtaposition on the Galisteo formation and the erosion of overlying Holocence terrace deposits.

The steady-state and dynamic response of a butyrate using methanogenic consortia has been modeled as three sequential bacterial growth reactions. The model simulates the concentration of fermentation intermediates (acetate and hydrogen), incorporating their inhibition of butyrate oxidation and stimulation of methanogenesis. The hydrogen-producing acetogenic conversion of butyrate is modeled as a product-inhibited or reversible, modified Monod reaction, while hydrogen-using and acetoclastic methogenesis are simple Monod reactions. The growth yield coefficient for each growth reaction is variable and dependent on the Gibbs free energy of the energy reaction, which in turn depends on the time-varying concentrations of reactants and products

An innovative, short-term corrosion test has been developed that can predict long-term copper corrosion behavior. When used in a six-day study of uniform copper corrosion in five waters, the test predicted corrosion rates that were in good qualitative and quantitative agreement with known long-term (210-day) results. A second phase of the study examined the poorly understood phenomenon of soft-water pitting. Initial work successfully reproduced soft-water copper pitting in the laboratory using a synthetic water, facilitating future studies of pit initiation and potential remedies. Relative pitting tendencies were predicted using the short-term test, as was the long-term release of the by-products of copper corrosion. Pitting severity increased with increasing pH and duration of stagnation and decreased in the presence of natural organic matter or chlorine residuals.

Bioremediation of simulated ground water containing 2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), and pentachlorophenol (PCP) was studied in a laboratory-scale aerobic fluidized-bed reactor. Chlorophenols were the sole source of carbon and energy in the enrichment culture. At a hydraulic retention time of 5 h and chlorophenol loading rate of 445 mg L -1 d -1 , stable chlorophenol removal of over 99.7% and adsorbable organic halogen removal of 99.4% were maintained with the mean inorganic chloride release (ICl) of 94%

Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench-top reactors and in serum bottle tests. Three continuously mixed daily batch-fed reactor systems were evaluated: anaerobic, aerobic, and sequential–anaerobic-aerobic (sequential). Glucose, acetate, benzoate, and phenol were fed as growth substrates to both the anaerobic and aerobic systems. Methane and toluene were also added to the aerobic systems to induce cometabolic degradation of the feed CACs. The anaerobic culture degraded seven of the feed CACs. The specialized aerobic cultures degraded all but three of the highly chlorinated CACs. The sequential system outperformed either of the other systems alone by degrading 10 of the feed CACs: chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,1,1-trichloroethane, hexachloroethane,, 1,1-dichloroethylene, trans-1,2-dichloroethylene, trichloroethylene, perchloroethylene, and 1,2,3-trichloropropane, plus the anaerobic metabolites: dichloromethane and cis-1,2-dichloroethylene. Sequential treatment did not show significant removal of 2-chloropropene, or 1,1-dichloropropene. Cultures from each of the reactors were used in bottle tests to determine relative CAC degradation rates. Maximum degradation rates observed for individual CACs ranged from 20 to 150 μ\Ng per gram volatile suspended solids per day.

The microbial degradation of butyrate was studied in a continuous-flow anaerobic fluidized-bed reactor. The reactor characteristics at steady-state butyrate loading, and in response to transient loadings of butyrate, hydrogen, acetate, and formate, were determined using an on-line computerized data acquisition system. The fluidized-bed reactor operated at a steady-state butyrate loading of 10 g of chemical oxygen demand (COD)/L-day and at an unusually high specific loading rate of 8-10 g of COD/g of volatile solids per day, achieving >97% COD removal

Objective— To describe the use of a 3.5/2.7 mm CastLess Plate (CLP) for pancarpal arthrodesis (PCA) in dogs. Study Design— Case series. Animals— Dogs with traumatic/degenerative carpal disease (n=11). Methods— Records (September 2006–July 2007) of dogs that had PCA using a 3.5/2.7 mm CLP were reviewed to determine intra- and postoperative complications and use of external coaptation. Follow-up (≥12 months) was obtained by telephone interview of owners. Results— Thirteen PCA procedures were performed; 5 intraoperative complications occurred in 4 procedures and included iatrogenic metacarpal fissure fracture (2), inability to remove an alignment pin (1), and poor distal plate position (2). External coaptation was used in 4 dogs: concomitant or iatrogenic injuries (3), bilateral PCA (1), for 3–6 weeks. Clinical evaluation 6–24 weeks postoperatively revealed iatrogenic metacarpal fractures to have healed and that 1 postoperative complication (infection) developed. Telephone follow up for 10 dogs (mean, 14 months; range, 12–20 months) revealed no further problems. Conclusion— PCA using a 3.5/2.7 mm CLP reduces the need for external coaptation and seemingly reduces postoperative morbidity associated with other internal fixation techniques. Clinical Relevance— PCA can be performed safely and successfully using a 3.5/2.7 mm CLP, with low postoperative morbidity compared with other PCA techniques. Particular attention should be taken when applying the distal component of the plate.

This study examined changes of colloidal properties and lead release from representative solid phases of lead (IV) (PbO2) and lead (II) (hydrocerussite, cerussite) and during the oxidation of the lead (II) solids by chlorine. Chlorine is determined to cause the zeta-potential of lead (II) solids to undergo significant changes apparently associated with the generation of Pb(lll) intermediates that are formed before the PbO2 phase becomes abundant enough to be morphologically distinct. Simultaneouslywith the changes of the zeta-potential, a pronounced decrease of lead release from hydrocerussite takes place. In contrast with that, lead release from cerussite undergoes a transient increase during the oxidation of that solid by chlorine. The existence of differences in processes governing lead release from these Pb(ll) solids is supported by SEM data showing different patterns of morphological changes of the cerussite and hydrocerussite crystal surfaces.

Students of the Summer of Applied Geophysical Experience (SAGE), a field-based educational program in applied geophysical methods, studied the 60-acre San Marcos Pueblo archaeological site in northern New Mexico as part of an ongoing geophysical investigation. In 2008 ground penetrating radar (GPR), seismic refraction, electromagnetic and magnetic surveys focused on parts of the pueblo in use during the early colonial period, prior to the pueblo revolt in 1680 when the population of the pueblo approached its peak. Electromagnetic and magnetic data showed strong anomalous responses that correlated with the topography of room blocks, and fluvial erosion channels carrying conductive and magnetic material from a known metallurgical smelter and slag pit high. In addition several larger-scale geologic and archaeologic features were identified in the magnetic data defining kivas (ceremonial chambers). GPR data showed a distinctive feature that is possibly part of a room block, the smelter pit and a storage area. Three seismic refraction lines were added to the continuing investigation and not only identified two fire pits with the help of magnetic data, but provided a three-dimensional representation of the underlying geologic structure.

A study of anaerobic removal of adsorbable organic halide (AOX) from kraft bleaching wastes has been conducted, using bottle bioassay techniques. The anaerobic cultures were fed either acetate or hydrogen and were able to remove from 40 to 65% of the AOX. The removal mechanism and the role of an adapted anaerobic consortium has been investigated with results indicating some biological removal, but significant amounts of sorption or degradation that does not seem to require microbial activity. Significant inhibition of methanogenic activity has also been found in some of the tests.

A model of the subsurface structure of the eastern part of the Española Basin in the northern Rio Grande rift of New Mexico was constructed from geophysical data obtained since 1983 by the Summer of Applied Geophysical Experience (SAGE) field course. Approximately 742 new gravity observations, 1276 ground magnetic stations, 30 km of seismic refraction lines, 19 km of seismic reflection lines, 22 magnetotelluric stations, and several Schlumberger and dipole‐dipole resistivity lines were established. Our studies provide new information on one boundary of a major continental rift and on the depositional and structural style of an extensional basin within the rift. Integration of these data sets into a single transect indicates that the Española Basin is asymmetrical with approximately 2 to 3 km of sediments and sedimentary rocks near the center, thinning eastward to the Precambrian outcrop of the flanking Sangre de Cristo uplift. Several minor faults with throws of less than 200 m were found, but no major eastern bounding fault was observed. Thus, the Española Basin could be an asymmetrical, west‐dipping half‐graben. However, major fault offset, down toward the basin axis, may occur within Precambrian rocks of the Sangre de Cristo uplift. In either case, the geometry of the basin does not agree well with current models for the structural evolution of continental rifts, which emphasize low‐angle detachment faults which create asymmetrical, hinged half‐grabens. These models predict that major shoulder uplift should occur adjacent to the side of the graben bounded by a listric master fault rather than adjacent to the hinged side. In contrast, for the Española Basin major uplift occurred adjacent to the eastern side, which could be the hinged side of the basin. A thick wedge of older sedimentary rocks with high P‐wave velocity (4.4 km/s) and low electrical resistivity (5 Ω⋅m) was discovered under the younger Tertiary sediments and sedimentary rocks near the center of the basin. This wedge has maximum thickness of 1.2 km at the western end of the profile and thins eastward. The physical properties suggest this layer could be older Tertiary, or possibly a Mesozoic‐Paleozoic, section of rocks. If the latter, it has potential economic importance because of the possible presence of a Cretaceous section which is known to produce oil and gas in the Albuquerque Basin to the south and the San Luis Basin to the north. However, based on data from the Yates La Mesa no. 2 well, 10 km south of the transect, this wedge is likely middle Tertiary lacustrine deposits (NMOCD, 1986). The great thickness of lake deposits may represent a major lacustrine facies of the Eocene Galisteo and El Rito formations, exposed around the southern, southwestern, and northwestern margins of the basin. Magnetotelluric data suggest the crystalline basement underlying the central Española Basin may be more conductive than near the eastern margin. The entire Española Basin is also underlain by a highly conductive layer of about 1 Ω⋅m at a depth of 15 km. Both the shallow and deep low‐resistivity zones may result from hot, saline fluids. Such fluids deep within the crust may reduce the shear strength of the crust significantly and concentrate crustal extension on the west side of the rift.

An upper bound estimate of the vertical component of stress present at oceanic convergent zones is obtained by examining the flexural style of the downgoing plate. A least squares procedure is used to invert the equations governing the flexure of a thin elastic plate, yielding an estimate of the plate's rigidity, and the lateral distribution and magnitude of the vertical stress. The stress estimates obtained from the elastic plate model are upper bounds, since any anelasticity will tend to weaken the lithosphere and thus require a smaller load to produce the same flexural response. Analyses of the Mariana, Bonin, Kuril and Aleutian Trenches show that the stress inducing lithospheric flexure reaches a maximum of less than 20 MPa within a few kilometers arcward of the trench. In all but the Aleutian Trench, the load decays to less than 1 MPa within 60 km of the trench, well before the Benioff Zone dip steepens. The distance between the trench axis and the stress maximum, as well as the net force applied to the plate, increase with increasing convergence rate. The estimated stress profiles are consistent with a model in which the stress inducing flexure results from the collision of the two plates along a narrow zone of interplate coupling located 15 to 20 km arcward of the trench axis. The trenches studied do not require a large vertical load in the vicinity of the steep part of the Benioff Zone, indicating that the weight of the subducted slab does not contribute support to the trench/outer rise bathymetry. This requires the normal component of slab weight to be supported by the asthenosphere, allowing the remaining component of weight to act parallel to the plate axis.

Aceticlastic methanogens are seen as a key to digester capacity and stability. This paper develops and applies an assay to measure digester stability by measuring the maximum aceticlastic methane production rate (Vmax,ac). The Vmax,ac in combination with acetate concentrations was found to be an effective digestion monitoring tool to indicate process upsets. At steady state, thermophilic, first stage and short SRT digesters generally had a greater Vmax,ac than mesophilic, second stage or long SRT digesters. The ratio of the Vmax,ac to the plant aceticlastic methane production rate, termed the Acetate Capacity Number (ACN), is a measure of the excess capacity of the digester. Either Vmax,ac or ACN can be used to estimate the capability to handle higher organic loading rates. Monod modeling was used to predict Vmax,ac, ACN and maximum VS loading rates for mesophilic and thermophilic digestion and for staged digesters to better understand expected digestion capacity and stability.

Anaerobic acetate utilizing cultures were enriched from three different environments of pulp mill wastewater and subsequently subcultured on calcium acetate and calcium acetate plus sodium sulfate media. Microbial acetate conversion was complete in all cases where methanogens tolerant to sulfur compounds were present, even at 4.6 g SO 4 2− /l. Acetate conversion by sulfate reduction was significant only in methanogenic cultures sensitive to sodium sulfate or its metabolic products. Sulfate reduction was always incomplete although acetate was present in excess. Sulfate reducing capacity persisted in continuous cultivation of sludge for at least 2 years in the absence of oxidized sulfur compounds. Tolerance of acetotrophic methane-producing bacteria from pulp mill wastewater sludge towards sulfur compounds (sulfate plus its metabolites) was preserved beyond an experimental exposure of 6 months (6 transfers) to acetate-only medium. Another methanogenic enrichment culture from pulp mill sludge developed sensitivity towards sulfur compounds after being continuously cultured in an environment lacking oxidized sulfur compounds for 2 years.

Equilibria and kinetics of transformations in the Pb(II)/Pb(IV)/chlorine system have a great impact on lead release in drinking water. To explore this system, oxidation of representative Pb(II) solid phases, predominantly hydrocerussite was carried out in chlorinated water with various alkalinities and pH values. It was determined that the oxidation of hydrocerussite by chlorine proceeded via three phases. These included a lag phase, a rapid transition phase and a final quasi steady-state phase. The lag phase corresponded to the transformation of hydrocerussite to cerussite PbCO3, while during the transition phase, the oxidation of PbCO3 and formation of -PbO2 occurred. Key water parameters, such as pH, chlorine concentration and dissolved inorganic carbonate concentration had a pronounced impact on the duration of the lag phase. Data of X-ray diffraction and scanning electron microscopy demonstrated that cerussite PbCO3 was formed as a transient phase during hydrocerussite oxidation, and dispersed microcrystals of scrutinyite -PbO2 were formed when chlorine was consumed.

The world's first 4-D surface gravity surveillance of a waterflood has been implemented at Prudhoe Bay, Alaska. This monitoring technique is an essential component of the surveillance program for the Gas Cap Water Injection Project (GCWI). A major factor in the approval process for the waterflood was to show that we could economically monitor water movement where a very limited number of wells penetrated the waterflood area. The drilling of numerous surveilence wells to adequately monitor water movement would have been cost prohibitive. Field surveys now conclusively show that density changes associated with water replacing gas are being readily detected using high-resolution surface gravity measurements. The gravity methods used to monitor the waterflood include time-lapse (4-D) measurement of surver the reservoir followed by inversion of the 4-D signal for mass balance and flood front detection. This paper will focus on field results of time-lapse surface gravity surveys. Differences in the gravity field over time reflect changes in the reservoir fluid densities. The inversion procedure was formulated and coded to allow for various constraints on model parameters such as density, total mass, and moment of inertia. The gravity survey was designed to permit the inversion for reservoir mass distribution with resolution on the order of hundreds of meters in the presence of uncorrelated noise of reasonable magnitude (12 µGal standard deviation). Time differenced gravity survey results clearly show an increase in surface gravity that is a result of the injected water mass. Density-change maps deduced from measured gravity- change show that water movement is reasonably similar to the reservoir simulations and the water detected in observation wells. The overall ultimate gravity signal is predicted to increase to approximately 250 µGal ultimately resulting in accurate maps of the water movement.

Permanganate has been used for oxidation of nuclear wastes containing chelating agents such as ethylenediaminetetraacetic and nitrilotriacetic acids (EDTA and NTA) to improve separation of radionuclides and heavy metals from the wastes, butthe mechanisms of degradation of these and related organic ligands at high pHs have not been studied. EDTA, NTA, and the model compound ethylenediamine (EN) were found to be readily oxidized by permanganate at pH 12-14. The reduction of permangante was accompanied by formation of unstable manganate and dispersed MnO2 particles, which constituted the final product of permanganate reduction. The yields and speciation of EDTA, NTA, and EN breakdown products were affected by the pH and permanganate dose. Iminodiacetic acid (IDA), oxalate, formate, and ammonia were the predominant EDTA and NTA oxidation products. Mineralization of EDTA, NTA, and EN to CO2 was more significant at pH 12. At pH 14 formation of oxalate and deamination to NH3 were the most important reactions. IDA was released upon the oxidation of both EDTA and NTA, but EDTA oxidation yielded no ethylenediaminediacetic acid (EDDA). The speciation of the reaction products indicated that the ethylene group in EDTA was the preferred attack site in oxidations by alkaline permanganate.