ISSN:0730-7268    

DOI:10.1002/etc.5620140801

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractData are presented on the application of the reversed‐phase separation technique for the determination of dissolved organic compounds in estuarine interstitial water. Thirty‐seven neutral, nonpolar organic compounds were equilibrated with interstitial water, extracted by emulsion‐free gentle liquid‐liquid extraction, and quantified using surrogate internal standards. The extraction and quantitation procedures were insensitive to dissolved organic carbon concentration (DOC, 1 to 55 mg C/L). Gross dissolved organic carbon retention by the C18matrix (7 ± 2%) was similar to the range reported for fresh water; significant regressions of apparent, DOC‐normalized, partition coefficients (K′doc) versus compound solubility and octanol/water partition coefficients (Kow) were determined. An inverse relationship betweenK′docand DOC concentrations, similar to that reported in fresh water, was found, but was reduced or eliminated for many compounds by accounting for the retained bound compound in the calculation ofK′doc; failure to account for C18retention of DOM in determining freely dissolved concentrations of highK′oworganic compounds could result in overestimates of this fraction. Partition coefficients of selected compounds between Aldrich humic acid and distilled water were similar to those found in other studies using radi

ISSN:0730-7268    

DOI:10.1002/etc.5620140802

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractBecause of the widespread use of glycol ethers in applications ranging from consumer products to use as chemical intermediates, there is a need to better understand the fate of these compounds in the environment. Soil biodegradation studies were conducted for three propylene glycolethers: 1‐methoxy‐2‐propanol, 1‐phenoxy‐2‐propanol, and 1‐methoxy‐2‐propanol acetate. The test compounds were labeled with carbon‐14 at either the methoxy or phenoxy substituents. Biodegradation of the three compounds was observed in two sandy loam soils. The time required for disappearance of 50% of the test compounds ranged from<1 d at 0.2 ppm (w/w) to<7 d at 107 ppm. Degradation rates were slower in a sandy soil, reflecting the lower concentration of microorganisms present. No significant accumulation of intermediate products was observed, and ultimate yields of14CO2were in the range of 40 to 65% of the initial concentration. Results indicated that the glycol ethers were degraded in a variety of soils under

ISSN:0730-7268    

DOI:10.1002/etc.5620140803

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSoil, sediment, and paint sludge samples were collected during a 4‐year period from an abandoned solvent recovery site prior to and after site remediation. Samples were sequentially extracted with methylene chloride and methanol and redissolved in dimethyl sulfoxide for biological analysis. The mutagenic potential of the extracts was evaluated using theSalmonella/microsome assay with and without metabolic activation. Noncontaminated background soil samples collected off‐site induced specific mutagenic activities that ranged from below detection to 28 net revertants per milligram of residue. Although several sludge samples induced specific activities that were relatively low, the maximum mutagenic response induced by a sludge sample was 1,258 net revertants per milligram of residue. Compared to background soil, elevated levels of mutagenic activity were also detected in the extracts of several samples collected from a drainage area downgradient from the waste storage pad and in the extract of sediment samples from a downgradient storm‐water retention pond. The weighted activity of the noncontaminated background soil samples ranged from below detection to 15 revertants per gram of soil. The combined weighted activity of the sludge sample extracts ranged from below detection to 43,567 revertants per gram. The combined weighted activity of the extracts of samples collected after site remediation ranged from below detection to 1,273 revertants per gram. A visual inspection of the site following remediation suggested that all obvious signs of chemical contamination had been removed. However, the results from biological analysis indicate that soil collected following site remediation induced a weighted activity more than 30 times the maximum weighted activity observed in the noncontaminated background soil. These data suggest that additional site remediation is required if the genotoxic potential of soil is to be reduced to levels approximating those of noncontaminated background

ISSN:0730-7268    

DOI:10.1002/etc.5620140804

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe photochemical degradation of the herbicides alachlor (2‐chloro‐2′,6′‐diethyl‐N‐methoxymethylacetanilide) and bentazone (3‐isopropyl‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one‐2,2‐dioxide) in distilled water and in river water, under xenon arc lamp irradiation, was investigated. Analytical determinations were carried out by using a xenon arc photoreactor and online solid‐phase extraction coupled to liquid‐chromatography diode‐array and liquid‐chromatography mass‐spectrometry detection systems. Photolysis experiments were performed at low concentration (20 μg/L), and the advantages of this methodology over conventional techniques are discussed. The photodegradation of alachlor and bentazone is a process depending on the water type, humic substances, and pH. When using a solution of 4 mg/L of humic matter, the estimated alachlor and bentazone half‐lives were 84 and 150 min, respectively, using a total irradiance of 550 W/m2in the range of 300 to 800 nm. The degradation of alachlor and bentazone followed pseudo second‐ and first‐order kinetics, respectively. The major photodegradation products of both herbicides were identified either by on‐line solid‐phase extraction (SPE)‐liquid chromatography‐thermospray mass spectrometry (LC/TSP‐MS) or on‐line‐SPE‐LC/TSP‐tandem mass spectrometry (LC/TSP‐MS/MS). In addition to that, a total of six transformation products of alachlor were synthesized in our laboratory and their MS spectra were compared with those of the breakdown products obtained. After photodegradation, a total of 14 photoproducts resulted from alachlor dechlorination with subsequent hydroxylation and cyclization processes. The two major photoproducts were identified as hydroxy‐alachlor and 8‐ethyl‐1‐methoxymethyl‐4‐methyl‐2‐oxo‐1,2,3,4

ISSN:0730-7268    

DOI:10.1002/etc.5620140805

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractPrevious studies on one soil showed that silicone polymer (polydimethylsiloxane, or PDMS) degrades to dimethyl‐silanediol (DMSD). This study examines PDMS degradation on seven U.S. soils differing in pH, % organic matter, texture, mineralogy, and geographic origin. Moist soils were amended with 350‐centistoke (cs) [14C]PDMS at 100 mg kg−1, and soils were dried at 23°C for 0, 2, 4, 7, 10, or 14 d. Foam plugs were inserted in tube necks to trap volatiles. Samples were extracted with water to monitor silanol formation, or with THF (tetrahydrofuran) for analysis of molecular weight changes and identification of degradates. In all soils, PDMS degraded extensively to low‐molecular‐weight, water‐soluble products. Gas chromatography‐mass spectrometry (GC‐MS) identified the main product in all soils as DMSD. Other small silanols and cyclic siloxanes were either not detected or were present in only trace amounts. No volatile14C was captured by the plugs, and quantitative recovery of14C showed no loss of unidentified volatiles. PDMS degradation was thus similar in a wide range of soils, and DMSD was the main degradate. A lower limit of 4,900 ± 1,250 L kg−1for thekdof this PDMS suggests that the polymer should

ISSN:0730-7268    

DOI:10.1002/etc.5620140806

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe fate and the effects of triclopyr butoxyethyl ester (TBEE) were investigated in a first‐order forest stream. Quantification of TBEE in stream‐water samples showed maximal concentration of 0.848 and 0.949 μg ml−1at sampling stations nearest two discrete injection points. Average TBEE concentrations ranged from 0.32 μg ml−1at stations nearest injection points to 0.02 μg ml−1approximately 225 m downstream. Periods of exposure to aqueous TBEE concentrations in excess of 0.001 μg ml−1ranged from 55 min in fast‐flowing upstream locations to 120 min at slower, downstream sampling locations. Simultaneous quantitation of triclopyr acid (TRI) residues in stream‐water samples indicated that natural degradative mechanisms rapidly converted TBEE to TRI, and that sorption to natural allochthonous materials occurred as chemical pulses moved downstream. Chemical behaviour resulted in short‐term, pulse‐type exposures to TBEE, with decreasing magnitude and slightly increasing duration in relation to downstream distance. Short‐term, low‐level exposures generated in this stream treatment resulted in slightly elevated drift (∼3‐ to 4‐fold increase) for up to 36 h, but no measurable reductions in abundance of benthic invertebrates. Increases in chlorophyllaconcentrations in epilithic periphyton from treated sections indicated short‐term eutrophication or growthregulation ef

ISSN:0730-7268    

DOI:10.1002/etc.5620140807

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractBetween 1989 and 1991, reproduction by black‐crowned night‐herons (Nycticorax nycticorax) and snowy egrets (Egretta thula) was studied at sites in San Francisco Bay. Eggs were collected from these and other bay sites and from South Wilbur Flood Area, a reference site in California's San Joaquin Valley. Eggs were analyzed for inorganic trace elements, organochlorine pesticides, and polychlorinated biphenyls (PCBs). Results were compared among sites and years and with results of previous studies. There was some evidence of impaired reproduction, but concentrations of contaminants were generally lower than threshold levels for such effects. Egg hatchability was generally good, with predation being the factor that most limited reproductive success. Mean PCB concentrations were generally higher in eggs from the south end of San Francisco Bay than from the north, but the only temporal change, an increase, was observed at Alcatraz Island. There were spatial differences forp,p′‐DDE in night‐heron eggs in 1990, but the highest mean concentration of DDE was in night‐heron eggs from South Wilbur in 1991. Temporal declines in maximum concentrations of DDE in eggs were observed in the bay, but means did not change significantly over time. At Bair Island in the southern end of the bay, mean concentrations of mercury decreased while selenium increased in night‐heron eggs over time, but there were no clear bay‐wide spatial or temporal trends for

ISSN:0730-7268    

DOI:10.1002/etc.5620140808

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractManipulations of freshwater sediment were performed to remove indigenous organisms prior to conducting toxicity tests with three species of benthic invertebrates. The effects of these treatments on end points in bioassays were compared within and between two sediments, i.e., a “clean” sediment and a “contaminated” sediment. In addition, the effects of manipulations on the physicochemical structure of the two sediments and the presence of metals, PAHs, and PCBs in the contaminated sediment were examined. The amphipodHyalella aztecawas most sensitive to the manipulations and had low survival in sediment that was sterilized. Growth (milligrams dry weight per individual) was affected by the presence of contaminants. Survival ofChironomus ripariuswas not affected by any manipulation but was reduced by contaminants as well as indigenous organisms. Growth ofC. ripariuswas higher in autoclaved sediment but lower in sediment containing endemic tubificid worms. Production of young byTubifex tubifexincreased in sediment that was irradiated, possibly due to increased detrital material. Particle size distribution, metals, nutrients, and PAHs varied little as a function of manipulation; however, sieving of sediment through 250‐μm mesh did reduce percent total organic carbon (TOC), percent loss on ignition (LOI), and concentrations of some PCBs in either clean or contaminated sediment. Manipulation of sediments to remove endemic species should be determined on a case‐by‐case basis and is specific to the organisms used in

ISSN:0730-7268    

DOI:10.1002/etc.5620140809

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractExposure to diflubenzuron concentrations of 2.5 μg/L reduced growth of young‐of‐the‐year (Y‐O‐Y) bluegill by 56 and 86% in replicate enclosures and by 88 and 97% at 30 μg/L. An adult bluegill reproduction study was conducted in six littoral enclosures located in a 2‐ha pond near Duluth, Minnesota. Decreased growth of Y‐O‐Y bluegill resulted from the reduction or elimination of preferred invertebrate prey items by diflubenzuron that led to different and/or less Y‐O‐Y food consumption. Adult bluegill behavior and spawning, embryo hatching, larval survival until swim‐up, and Y‐O‐Y biomass were also studied. Before the first two diflubenzuron applications, spawning occurred in all enclosures; following the first application, spawning occurred in both control enclosures and one 30‐μg/L enclosure. Successful embryo hatching and larval swim‐up occurred in all enclosures prior to the first application, and in one control and one 30‐μg/L enclosure following application. The Y‐O‐Y growth was the most sensitive end point, and Y‐O‐Y biomass was among the least sensitive end points for bluegill reproductive success. The Y‐O‐Y bluegills (and potentially other fish species) that are exposed to diflubenzuron concentrations of ≥2.5 μg/L may experience reduced growth, which can result in greater starvation, increased predation, reductions in over

ISSN:0730-7268    

DOI:10.1002/etc.5620140810

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY