摘要:

AbstractThe abilities of three types of sediment to biotransform trichloroethene (TCE) were compared to determine the influence of environmental factors that differ among sediments of different composition. The results could suggest TCE behavior at spill sites in a variety of subsurface materials.Microcosms containing water and sediment ranging from predominantly organic material to calcareous rock were spiked to contain 5 mg/L of TCE and allowed to incubate in the dark at 25°C. TCE was completely transformed tocis‐1,2‐dichloroethene (CIS) in one year by a sandy organic sediment that was contaminated with TCE prior to microcosm construction. Microcosms prepared with crushed rock and water, which contained low microbial biomass, depleted all the TCE spike in 21 months of incubation; however, less than 10% of the depleted TCE was recovered as 1,2‐dichloroethene. Sodium acetate was added to selected microcosms for the purpose of increasing active microbial populations; however, this had no effect on the depletion

ISSN:0730-7268    

DOI:10.1002/etc.5620060801

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe polychlorinated biphenyls (PCBs) in sediment and/or fish samples from at least five different locations show changes in gas chromatographic (GC) peak distribution indicative of reductive dechlorination. Several different dechlorination processes, each presumably mediated by a different population of anaerobic bacteria with its own distinctive pattern of PCB congener selectivity, appear to be operating. Six of these processes have been characterized in detail as to the changes occurring in each of the 126 individual PCB congeners or isomer groups detectable by capillary GC or GC‐MS on a DB‐1 column. The patterns of congener reactivity indicate that the observed transformation processes fall into two broad categories:o,m,p‐dechlorinations, which remove chlorine atoms from ortho, meta, and para positions, with congener reactivities primarily determined by reduction potential; andm,p‐dechlorinations, which take chlorines from meta and para positions only, with relative reactivities determined mainly by molecular shape. Both types of dechlorination preferentially remove PCB congeners of toxicological concern, and both produce lower congeners that are biodegradable by environmental aerobes. Thus, dechlorination in anaerobic sediments permits the detoxification and eventual degradation of environment

ISSN:0730-7268    

DOI:10.1002/etc.5620060802

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractLake Lansing, Michigan was treated with sodium arsenite for macrophyte control in 1957. Seven 1.5‐m sediment cores were taken along a line through the littoral zone to the deepest portion of the lake and analyzed for arsenic. In each core, arsenic concentrations going from the surface downward increased to some maximum and then receded to background. Depth of peak concentrations followed two patterns: three littoral cores showed peak arsenic at 0.13 m from the sediment surface, and four cores from progressively deeper portions of the lake showed a regular decrease in peak depth from 0.32 m to 0.17 m. Sediment accumulation rates were calculated along this transect. Particle‐size sorting of sediments along this slope was also measured. This work suggested that sediments originated from wetland vegetation at the edge of the lake. Turbulent movement of water in the shallows caused suspension and down‐slope movement of small particles. Fewer particles of wetland origin were available for sedimentation beyond the region of highest fallout (3.75 m), thus accounting for progressively lower sedimentation rates in deeper portions of the basin. A model was developed to predict the time it would take for surface sediments to reach pretreatment concentrations of arsenic levels; for Lake Lansing it would be more than 100

ISSN:0730-7268    

DOI:10.1002/etc.5620060803

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe use of ground water in lieu of soil to determine the biodegradation potential of organic pollutants in the subsurface was assessed. With one exception, the recovery of viable counts and mineralization of naphthalene in the ground waters, but not the soils, collected from boreholes at an abandoned creosote waste site suggest that ground water may contain a microflora not representative of the subsurface. In samples from an aviation fuel spill, the extent of benzene mineralization in aquifer material and well water (from a nearby monitoring well) was about the same, whereas mineralization of benzene in ground water (from the same borehole as the soil) was 4.5 times less after 28 d of incubation. Rates and extent of naphthalene mineralization and microbial numbers declined in samples of water collected after pumping 0, 3,6, and 9 well volumes from a well in a plume of creosote contamination. A method was developed by which a representative sample of ground water was collected by treating the well and proximate formation with 0.5% H2O2for 24 h and then continuously pumping for a second 24 h before the sample was collected for experimental use. The data suggest that determination of the biodegradation potential of subsurface pollutants using ground water is tenuous unless precautions are taken to ensure the microflora is representative of the subsurface.

ISSN:0730-7268    

DOI:10.1002/etc.5620060804

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe effects of temperature and nitrogen, phosphorus, and carbon enrichments on phenol mineralization were determined in the uppermost and deepest horizons of two contrasting soils. Soil samples were amended with trace levels of14C‐phenol and incubated under various experimental conditions. Mineralization was determined by measuring the production of14CO2with time. First‐order rate constants(k)and extent of mineralization (PO) were estimated from the resulting data using nonlinear regression. Temperature affected mineralization differently as a function of soil type. While not stimulating mineralization in the upper horizons, nitrogen and phosphorus enrichment resulted in faster and more extensive mineralization in the subsurface horizons. Carbon (cellulose) enrichment had little effect in any soil examined. This study demonstrates the importance of temperature and inorganic nutrient availability in controlling the biodegradation of a model pollutant in surface and subsurface soil. It further illustrates the variability that exists between soil types and between different horizons of the same soil type as to factors capable of influencing biodegradation proces

ISSN:0730-7268    

DOI:10.1002/etc.5620060805

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractStudies were undertaken to determine the presence of cadmium‐binding proteins in fish from a metal‐contaminated flyash disposal pond and relatively uncontaminated hatchery ponds. Fractionation of gill cytosolic proteins by gel filtration indicated three classes of cadmium‐binding proteins. While no cadmium was detected in the metallothionein (MT)‐like fraction of the hatchery fish, 1% of the cytosolic cadmium was detected in this fraction for ash pond fish. Cadmium concentrations in the flyash pond were previously reported as ranging from 0.30 to 0.98 μg/L. This level of exposure may be insufficient to induce significant biosynthesis of MT‐lik

ISSN:0730-7268    

DOI:10.1002/etc.5620060806

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe effect of hydrogen fluoride (HF) on the translocation and partitioning of14C between transport and nontransport photoassimilates from source leaves to sink regions was studied. Soybean plants (Glycine max(L.) Merr. cv ‘Hodgson 78’) were fumigated continuously with HF at 0, 1, and 5 μF‐m−3for 8 to 10 d at three stages of development (vegetative, flowering and early fruit set, and pod filling). The second fully expanded trifoliolate leaf of experimental plants was exposed to14CO2.In plants exposed to HF, there was an increased retention of14C‐labelled assimilates in foliage (source tissue), accompanied by a reduced export of these compounds to other plant parts (path and sink tissues). There was also a greater incorporation of14C into nontransport ethanolinsoluble assimilates at the expense of the ethanol‐soluble transport assimilates in source leaves. When compared with control plants, exposure to HF also increased the proportion of14C incorporated into sugars in source leaves accompanied by a decrease in14C‐sugars in sink tissues.Results suggest that the retention of sugars in source leaves and the reduction in allocation to sink tissue may be a result of the inhibition of the process involved in the export of sugars from the leaf (i.e., phloem loading). An inhibition of phloem loading may result in an accumulation of sugars in the mesophyll cells, which may exhibit feedback inhibition on starch degradation and/or stimulation of st

ISSN:0730-7268    

DOI:10.1002/etc.5620060807

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe experiments reported here describe the incorporation ofDaphnia magnainto the 7‐dCeriodaphniatoxicity test procedure of Mount and Norberg [1]. The addition ofD. magnato the procedure increased the number of parameters on which decisions regarding sublethal effects could be determined without significantly increasing the workload. In addition to the survival and productivity measures of the Mount and Norberg procedure, length and weight ofCeriodaphnia dubiaadults andD. magnaadults and neonates were evaluated.Methods for the culture and testing of both organisms usingSelenastrum capricornutumPrintz as the food source were described. An analysis of algal caloric content, chlorophyll a, cell number, mean cell volume, dry weight, number of bacteria, storage time, and time since the algae were “cleaned” was made to determine the characteristics of the feeding suspensions which most influenced the growth and productivity of the cladoc

ISSN:0730-7268    

DOI:10.1002/etc.5620060808

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY