Geology topics

L.B. Barber

Publications and source records attributed to L.B. Barber.

5 recordsLinked to original sources

USGS2002

Sorption of chlorobenzenes to cape cod aquifer sediments

Sorption of tetra- and pentachlorobenzene by sediment from a glacial outwash aquifer on Cape Cod, MA, was evaluated. Particle size and mineralogical fractions (separated based on paramagnetic susceptibility) were characterized with respect to sediment organic carbon (SOC), mineralogy, surface area, metal oxide coatings, and spatial variability. SOC increases by a factor of 10 as particle size decreases from 500-1000 to <63 um. Magnetic mineral abundance is a function of particle size and increases from 5 % in the 500-1000-xm fraction to > 25 % in the <63-um fraction, and SOC is preferentially associated with the magnetic minerals. Sorption increases with decreasing particle size (increasing SOC, magnetic minerals, surface area, and metal oxyhydroxides), and the magnetic mineral fraction has greater sorption than the bulk or nonmagnetic fractions. Removal of SOC decreases sorption proportional to the decrease in SOC and results in a nonlinear isotherm.

Environmental Science & Technology↗

USGS2002

Contamination of estuarine water, biota, and sediment by halogenated organic compounds: A field study

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. Contaminant concentrations in water, suspended sediments, and biota were found to be far below the values predicted on the basis of the assumption of phase equilibria with respect to concentrations in bottom sediment. Relative concentration factors of HOC between biota (catfish) and bottom sediment increased with increasing octanol/estuarine water partition coefficients (Kow*), maximizing at log Kow* of about 5, although these ratios were considerably less than equilibrium values. In contrast, contaminant concentrations in water, biota, and suspended sediments were much closer to equilibrium values. Bioconcentration factors of HOC determined on the basis of lipid content for four different biotic species correlated reasonably well with equilibrium triolein/water partition coefficients (Ktw).

Louisiana↗

USGS1995

Fate of linear alkylbenzene sulfonate in the Mississippi River

The 2 800-km reach of the Mississippi River between Minneapolis, MN, and New Orleans, LA, was examined for the occurrence and fate of linear alkylbenzene sulfonate (LAS), a common anionic surfactant found in municipal sewage effluents. River water and bottom sediment were sampled in the summer and fall of 1991 and in the spring of 1992. LAS was analyzed using solid-phase extraction/derivatization/ gas chromatography/mass spectrometry. LAS was present on all bottom sediments at concentrations ranging from 0.01 to 20 mg/kg and was identified in 21% of the water samples at concentrations ranging from 0.1 to 28.2 μg/L. The results indicate that LAS is a ubiquitous contaminant on Mississippi River bottom sediments and that dissolved LAS is present mainly downstream from the sewage outfalls of major cities. The removal of the higher LAS homologs and external isomers indicates that sorption and biodegradation are the principal processes affecting dissolved LAS. Sorbed LAS appears to degrade slowly.

Environmental Science & Technology↗

USGS1994

Organic compounds downstream from a treated-wastewater discharge near Dallas, Texas, March 1987

Water and streambed-sediment samples were collected on March 9 and 10,1987 from one site upstream and three sites downstream of the discharge from a municipal wastewater-treatment plant on Rowlett Creek near Dallas, Texas. To extract and separate organic compounds, purgeand-trap, closed-loop stripping, and pH-adjusted solvent extraction methods were used for water samples; and a Soxhlet-solvent extraction method was used for streambed sediment. These methods were combined with gas chromatography/mass spectrometry to identify organic compounds in Rowlett Creek. Results from this study confirm the persistence of many organic compounds in water as far as 13.5 kilometers downstream of the wastewater discharge. These include: (1) the volatile organic compounds chloroform, 1,2-dichlorobenzene, 1,4-dichlorobenzene, tetrachloroethene, and trichloroethene; (2) several linear alkylbenzene compounds, octyl phenol, and a tetramethylbutyl phenol isomer that are related to detergent use; (3) 9-phenyl-9H-carbazole, a compound related to coal tars and coal combustion residues; and (4) caffeine. The only compound present in water in concentrations greater than U.S. Environmental Protection Agency maximum contaminant levels for drinking water was tetrachloroethene (6.0 micrograms per liter) in a sample collected 13.5 kilometers downstream from the waste water discharge. Compounds identified from the streambed-sediment samples include a xylene isomer at 7.7 kilometers downstream and chrysene, fluoranthene, pyrene, and a xylene isomer at 13.5 kilometers downstream from the wastewater discharge. Comparison of instantaneous flux values of selected organic compounds in water from downstream sites indicates: (1) the formation of chloroform in the stream following the discharge of the treated effluent, and that (2) instream biodegradation may be decreasing concentrations of linear alkylbenzene compounds in water. The relative persistence of many of the selected organic compounds in Rowlett Creek downstream from the municipal wastewater-treatment plant indicates that they could be transported into Lake Ray Hubbard, a source of municipal water supply.

Texas↗

USGS1992

Identification of persisten anionic surfactant-derived chemicals in sewage effluent and groundwater

Preparative isolation and fractionation procedures coupled with spectrometric analyses were used to identify surfactant-derived contaminants in sewage effluent and sewage-contaminated groundwater from a site located on Cape Cod, Massachusetts. Anionic surfactants and their biodegradation intermediates were isolated from field samples by ion exchange and fractionated by solvent extraction and adsorption chromatography. Fractions were analyzed by 13C nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry. Carboxylated residues of alkylphenol polyethoxylate surfactants were detected in sewage effluent and contaminated groundwater. Linear alkylbenzenesulfonates (LAS) were identified in sewage effluent and groundwater. Groundwater LAS composition suggested preferential removal of select isomers and homologs due to processes of biodegradation and partitioning. Tetralin and indane sulfonates (DATS), alicyclic analogs of LAS, were also identified in field samples. Although DATS are a minor portion of LAS formulations, equivalent concentrations of LAS and DATS in groundwater suggested persistence of alicyclic contaminant structures over those of linear structure. Sulfophenyl-carboxylated (SPC) LAS biodegradation intermediates were determined in sewage effluent and groundwater. Homolog distributions suggested that SPC containing 3-10 alkyl-chain carbons persist during infiltration and groundwater transport. Surfactant-derived residues detected in well F300-50 groundwater have a minimum residence time in the range of 2.7-4.6 yr. LAS detected in groundwater at 500 m from infiltration has been stable over an estimated 50-500 half lives.

Conference Paper↗