Publications

Vapor sorption of water, ethanol, benzene, hexane, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,2-dibromoethane on (Sanhedron) soil humic acid has been determined at room temperature. Isotherms for all organic liquids are highly linear over a wide range of relative pressure, characteristic of the partitioning (dissolution) of the organic compounds in s

Water-resources investigations concerned with contaminant transport through aquifers comprised of very loose, unconsolidated sediments have shown that small-scale variations in aquifer characteristics can significantly affect solute transport and dispersion. Commonly, measurement accuracy and resolution have been limited by a borehole environment consisting of an annulus of disturbed sediments pro

Oxalic acid retards the alteration of Mn3O4 to γ-MnOOH during aging at pH 7.4 ?? 0.2 in well-aerated, abiotic suspensions that contain 4.4 ?? 10-3 M total Mn. In solutions of 1.25 ?? 10-3 M oxalate and greater, about 15% of the initial Mn3O4 altered to ??-MnOOH by day 10, and in solutions of 6.7 ?? 10-4 M oxalate, about 45% altered to ??-MnOOH by day 67. Although precipitation continued through da

Studies conducted in the vicinity of an industrial outfall in the Calcasieu River estuary, Louisiana, have shown that water, bottom and suspended sediment, and four different species of biota are contaminated with halogenated organic compounds (HOC) including haloarenes. A "salting-out" effect in the estuary moderately enhanced the partitioning tendency of the contaminants into biota and sediments

No abstract available.

Factors controlling the concentration of dissolved hydrogen gas in anaerobic sedimentary environments were investigated. Results, presented here or previously, demonstrated that, in sediments, only microorganisms catalyze the oxidation of H2 coupled to the reduction of nitrate, Mn(IV), Fe(III), sulfate, or carbon dioxide. Theoretical considerations suggested that, at steady-state conditions, H2 co

The fate of acetone in water was investigated in an outdoor model stream located in southern Mississippi, U.S.A. Acetone was injected continuously for 32 days resulting in small milligram-perliter concentrations in the stream. Rhodamine-WT dye was injected at the beginning and at the end of the study to determine the time-of-travel and dispersion characteristics of the stream. A 12-h injection of

Laboratory experiments were conducted with well-characterized minerals to test the applicability of selective extraction schemes for Se and As partitioning in soils and sediments. Two specific steps were tested: the reductive dissolution of amorphous iron oxides and the oxidation of organic material. Selenium and As associated with amorphous iron oxides were usually not found in solution after red

Deterministic, distributed-parameter, numerical simulation models for analyzing groundwater flow and transport problems have come to be used almost routinely during the past decade. A review of the theoretical basis and practical use of groundwater flow and solute transport models is used to illustrate the state-of-the-art. Because of errors and uncertainty in defining model parameters, models mus

Hydrologic and geochemical evidence were used to establish the long-term persistence of dichlorobenzene in ground water that has been contaminated from 50 years of rapid-infiltration sewage disposal. An extensive plume of dichlorobenzene extends more than 3,500 meters downgradient from the disposal beds, with concentrations of the combined isomers ranging from less than 0.01 to over 1.0 ??g/l. Bas

Photolysis of rhodamine-WT dye under natural sunlight conditions was determined by measuring the loss of fluorescence as a function of time. Rate coefficients at 30° north latitude ranged from 4.77 × 10−2 day−1 for summer to 3.16 × 10−2 day−2 for winter. Experimental coefficients were in good agreement with values calculated using a laboratory-determined value of the quantum yield.

Trace levels of ethane were produced biologically in anoxic sediment slurries from five chemically different aquatic environments. Gases from these locations displayed biogenic characteristics, having 12C-enriched values of δ13CH4 (−62 to −86%.), δ13C2H6 (−35 to −55%.) and high ratios (720 to 140,000) of CH4[C2H6+ C3H8]. Endogenous production of ethane by slurries was inhibited by autoclaving or b