ISSN:0730-7268    

DOI:10.1002/etc.5620131101

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA study was conducted on the effects of pH of the medium, composition of Fenton's reagent, and the effect of soil's preequilibration with the chemical, on the degradation of14C‐labeled free and complex cyanide in aqueous and soil‐containing systems The application of Fenton's reagent (1% H2O2, 10 mM FeSO4) resulted in degradation of 80% and 67% of potassium cyanide in aqueous systems at pH 7 2 and 10 0, respectively No appreciable amount of K4[Fe(CN)6] was degraded at either pH tested Under the alkaline condition, negligible amounts of cyanide were converted to HCN and were removed from liquid phase due to precipitation In the soil systems containing uncontaminated topsoil or manufactured gas plant (MGP) soil, both freshly amended with free cyanide, 80% of the compound was degraded by the Fenton's reagent of the same composition Similar to the aqueous systems, no complex cyanide was degraded in soil slurries In both soils, previously equilibrated with free and complex cyanides, the extent of degradation caused by Fenton's reagent was not more than 6% at either pH However, at alkaline pH, up to 21% of previously added complex cyanide was leached out into a liquid phase where it could be further degraded The optimum composition of Fenton's reagent under alkaline pH was found to be 1% of H2O2and 1 mM FeSO4We suggest that the application of Fenton's reagent under alkaline conditions may be useful in a combined physicochemical treatment for the remediation of sites contaminated with cyan

ISSN:0730-7268    

DOI:10.1002/etc.5620131102

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractHexavalent chromium [Cr(VI)] is a common environmental pollutant that is mobile in soils and is a known mutagen The trivalent form [Cr(III)]has no known mutagenic properties and is highly insoluble and immobile above pH 5 5 Reduction to the trivalent state thus represents an effective mechanism for detoxification and immobilization of Cr(VI) in soil/water systems In this study, we conducted experiments to examine various parameters involving aerobic reduction of Cr(VI) in a field soil We found that organic matter content, bioactivity, and oxygen status were important factors Under optimum conditions, the soil reduced 96% of added Cr(VI) under aerobic, field moist conditions The pH of the system was shown to have little effect Both biological and nonbiological processes were influential, and, of 20 chromate resistant bacterial cultures isolated from soils, 9 were found to actively reduce Cr(VI) to Cr(III) in liquid media Our study suggests that organic amended soils can readily reduce Cr(VI) and could promote excellent removal efficiency either as a primary treatment technique, or in conjunction with bioreactor type wastewater treatment systems

ISSN:0730-7268    

DOI:10.1002/etc.5620131103

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractIn this study, infrared spectroscopy (IR) was used to investigate the mechanism of interaction between the widely used herbicide Glyphosate [N‐(phosphonomethyl) glycine] and a water‐soluble humic acid (HA) obtained from a purified Leonardite Aliquots of the purified humic solution were set to pH 4, 5, and 6, and added with Glyphosate volumes corresponding to increasing percentages of total acidity of the water soluble HA The IR spectra of the HA‐Glyphosate complexes showed two bands at 1,168 and 1,090 cm−1for the stretchings of the P=O and P—O bonds, respectively, as they appear in the spectrum of Glyphosate alone where the phosphono group is involved in hydrogen bondings occurring in Glyphosate dimers Conversely, when the complex solutions were brought back to the starting pH levels (4, 5, and 6), the two IR bands of the phosphono group were shifted to higher frequencies (1,195 and 1,134 cm−1, respectively), suggesting that the P—O bonds were no longer involved in hydrogen bondings This behaviour supports the occurrence of hydrogen bondings in the Glyphosate‐HA complex In fact, the IR band shift in the herbicide‐HA complex indicates that, because the Glyphosate molecules are distributed along the humic macromolecule, they are too far apart to form the Glyphosate dimers again when the initial conditions are restored The hydrogen‐bonding interaction between HA and Glyphosate evidenced in this study may well be responsible for the transport of Glyphosate in lower soil depths through the adsorption of Glyphosate on water solu

ISSN:0730-7268    

DOI:10.1002/etc.5620131104

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractPhenol‐oxidizing enzymes such as peroxidases, laccases, and mushroom polyphenol oxidase are capable of catalyzing the oxidation of a wide range of phenolic pollutants. Although the use of these enzymes in waste‐treatment applications has been proposed by a number of investigators, little information exists on the toxicological characteristics of the oxidation products. The enzymes chloroperoxidase, horseradish peroxidase, lignin peroxidase, and mushroom polyphenol oxidase were used in this study to catalyze the oxidation of phenol, several mono‐substituted phenols, and pentachlorophenol. Seventeen reaction mixtures representing selected combinations of enzyme and parent phenol were subjected to mutagenicity screening using the AmesSalmonella typhimuriumplate incorporation assay; five selected mixtures were also incubated with the S9 microsomal preparation to detect the possible presence of promutagens. The majority of reaction mixtures tested were not directly mutagenic, and none of those tested with S9 gave a positive response. Such lack of mutagenicity of enzymatic oxidation products provides encouragement for establishing the feasibility of enzyme‐catalyzed oxidation as a waste‐treatment process. The only positive responses were obtained with reaction products from the lignin peroxidase–catalyzed oxidation of 2‐nitrophenol and 4‐nitrophenol. Clear positive responses were observed when strain TA100 was incubated with 2‐nitrophenol reaction‐product mixtures, and when strain TA98 was incubated with the 4‐nitrophenol reaction mixture. Additionally, 2,4‐dinitrophenol was identified as a reaction product from 4‐nitrophenol, and preliminary evidence indicates that both 2,4‐ and 2,6‐dinitrophenol are produced from the oxidation of 2‐nitrophenol. Possible mechanisms by which these nitratio

ISSN:0730-7268    

DOI:10.1002/etc.5620131105

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractSilicone (polydimethylsiloxane, or PDMS) fluids are widely used in industrial and consumer products and may find their way into municipal sludges that are eventually applied to the land. Earlier studies showed that PDMS degrades in soil to low‐molecular‐weight, water‐soluble silanols of the formula HO–[Si(CH3)2O]n–H. In this study, 200‐cs [14C]PDMS (1, 10, 100 mg kg−1) was placed in 50 g Londo sandy clay loam, and the soil was dried to generate the desired silanols in situ. The soil was remoistened and incubated at 25°C, 12% moisture, and 21% O2. The ultimate PDMS degradation product was identified by GC‐MS as dimethylsilanediol. During the next 4 months, from 25 to 50% of this substance was either volatilized from the soil, incorporated into the humus, or to a lesser extent oxidized to14CO2. The latter two processes increased with addition of alfalfa to the soil. No trend was seen in the loss of dimethylsilanediol over differen

ISSN:0730-7268    

DOI:10.1002/etc.5620131106

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractTwelve wildlife toxicology laboratories participated in an interlaboratory survey of cholinesterase (ChE) assays to determine comparability of absolute ChE values and estimates of ChE inhibition from organophosphorus insecticide‐dosed birds and to examine the type and consistency of methods employed by laboratories for the measurement of ChE Supernatants of brain from northern bobwhite quail (Colinus virginianus) were prepared from untreated (UT) and methyl parathion (MP)‐treated birds (5 mg/kg). Assays also were conducted on a commercial preparation of acetylcholinesterase from an electric eel. All laboratories performed the ChE assays using the colorimetric assay with temperature and read times varying by laboratory. There was substantial variation in the results of ChE analyses among participating laboratories The ChE values from untreated birds ranged from 2 6 to 28.0 μmol acetylthiocholine iodide (ACTI) hydrolyzed/min/mg tissue (mean = 14.8 sd = 7 1). For the MP‐treated group, ChE activity values showed a range of 1 5 to 15 3 μmol ACTI hydrolyzed/min/mg tissue (mean = 8 1, sd = 3 9) Percent inhibition values of MP‐treated compared to untreated birds ranged from 37 to 51% for reported results and 37 to 49% for corrected data (activity calculated from reported absorbance data) Laboratories were most consistent in their estimates of percent inhibition of ChE activity Differences among laboratories were partially explained by differences in the methods employed for the analysis of ChE. Assay temperature and duration appeared to affect the absolute values the most However, differences in reported ChE activity values existed even when methods were very similar These results do not support the concept of using published normal ChE values from other laboratories to assess ChE inhibition in field‐colle

ISSN:0730-7268    

DOI:10.1002/etc.5620131107

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe amphipodDiporeiaspp. was exposed to pyrene(0.14 to 1.11 μmol g−1) or phenanthrene (0.08 to 0.62 μmol g−1)‐dosed sediments for month‐long exposures. Phenanthrene was only slightly toxic with 12±3% mortality at the highest sediment dose (0.62 μmol g−1). Failure to attain and maintain toxic residue body burdens, based on a nonpolar narcosis concentration of approximately 6 μmol g−1, accounts for the low mortality. Phenanthrene toxicokinetic parameters were essentially constant among all doses and consistent with previous measures. Sediment concentration was a poor representation of dose for mortality by pyrene. The relative pyrene distribution among the<63‐μm particles increased in the smallest‐sized particles at larger doses. An apparent stimulation of pyrene accumulation was observed as a peak in uptake clearance values between sediment concentrations of 0.16 and 0.26 μmol g−1dry sediment. (Uptake clearance is the amount of source scavenged of contaminant per mass of organism per time.) The pyrene particle‐size distribution and the variation in kinetics with dose provide a partial explanation for the poor representation of dose by the sediment concentration. The pyrene body burdens provided a good dose response yielding LD50 values of 6.3 (4.6–41.7, 95% C.I.) and 9.4 (7.9–54.2) μmol g−1for two experiments. These values are consistent with the residue concentrations for 50% mortality by a nonpolar narcosis mechanism. Comparing the experimental and predicted equilibrium partitioning‐based sediment concentrations for 50% mortality, the equilibrium prediction overestimates the toxic pyrene sediment concentration by approximately a factor of ten.Diporeiabehavior, differential particle‐size distribution, and kinetic limitations appear as likely reasons for the variation between calculated and observed concent

ISSN:0730-7268    

DOI:10.1002/etc.5620131108

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractTime‐dependent toxicity in bioassays is usually explained in terms of uptake and elimination kinetics of the toxicant By comparing different species with essentially different accumulation kinetics, a firm test of this concept may be made This article compares the sensitivity of six soil arthropods, the collembolans Orchesella cincta andTomocerus minor, the oribatid mitePlatynothrus peltifer, the isopodsPorcellio scaberandOniscus asellus, and the diplopodCylindroiulus britannicus, when exposed to cadmium in the food Survival was determined at various time intervals, accumulation of cadmium in the animals was measured at one time interval Kinetic based toxicity models were fitted to the data, and estimates were obtained for lethal body concentration, uptake rate constant, elimination rate constant, and ultimate LC50 Two different accumulation patterns could be discerned, these were correlated with time‐survival relationships One, species that have the possibility to eliminate cadmium will reach an equilibrium for the internal concentration and also an ultimate LC50 Two, species that are unable to eliminate cadmium but store it in the body will have an ultimate LC50 equal to zero For these species the time in which the lethal body concentration is reached is more important Taxonomically related species appeared to have comparable accumulation patterns, but lethal body concentrations differed It is concluded that knowledge of the accumulation pattern is indispensable for the evaluation of species' sensitivities to toxic

ISSN:0730-7268    

DOI:10.1002/etc.5620131109

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractStandard 10 d toxicity tests were conducted with freshwater benthic invertebrates using sediments containing a range of concentrations of polycylic aromatic hydrocarbons (PAHs) The assays were performed both under normal laboratory fluorescent light and ultraviolet (UV) light, which mimicked wavelengths present in sunlight, at about 10% of ambient solar intensity In sediments with elevated PAH concentrations, tests conducted with UV light resulted in significantly greater mortality ofHyalella azteca(amphipods) andLumbriculus variegatus(oligochaetes) than tests performed under otherwise comparable conditions with fluorescent light There also was increased mortality of these two species, relative to controls, when surviving organisms from the 10‐d exposures to the PAH contaminated sediments were placed in clean water under UV light for 2 h These results suggest that the organisms accumulated PAHs from the test sediments, which were subsequently photoactivated by UV light to excited states more toxic than the ground state molecules The phenomenon of photoactivation has been examined for pelagic species exposed to PAHs, but not for benthic organisms exposed to sediment‐associated PAHs Our results suggest that failure to consider photoactivation of PAHs by sunlight could result in sediment toxicity test methods or criteria that are underprotective of benthic organ

ISSN:0730-7268    

DOI:10.1002/etc.5620131110

出版商:Wiley Periodicals, Inc.    

年代:1994

数据来源: WILEY