摘要:

AbstractA study of the effects of the insecticide chlorpyrifos on soil microbial activity was made. Parameters included total bacterial populations, fungi, aerobic N2‐fixing bacteria, denitrifying bacteria, nitrifying bacteria, nitrogenase activity, acid and alkaline phosphatases, arylsulfatase, and dehydrogenase. The presence of 2.0, 3.5, 5.0, and 10.0 kg/ha of chlorpyrifos significantly (p<0.05) decreased aerobic dinitrogen‐fixing bacteria and dinitrogen fixation, particularly after a second insecticide treatment The total number of bacteria increased significantly at concentrations of 2.0 to 10.0 kg/ha. Activities of acid and alkaline phosphatases and dehydrogenase significantly decreased initially at concentrations of 2.0 to 10.0 kg/ha, but recovered after 14 d to levels similar to those in control soil without chlorpyrifos. Fungal populations, nitrifying bacteria, and denitrifying bacteria were not affected as a consequence of the addition of the insectic

ISSN:0730-7268    

DOI:10.1002/etc.5620140201

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe compared trimercapto‐s‐triazine (TMT) to ethylenediaminetetraacetate (EDTA) for detoxification of five selected heavy metals as part of an effluent fractionation procedure. Toxicity was assessed using a microbial microplate assay, based on the MetPAD™ test kit. The affinity of TMT to four of the metals (Cd, Cu, Hg, Pb) was on the same order of magnitude as EDTA, as indicated by minimum mole ratios of ligand to metal required for detoxification. The TMT was ineffective against Zn. Both TMT and EDTA were toxic (causing more than 30% inhibition) to the test bacterial enzyme at concentrations of 3,000 μM or greater. The range of TMT concentrations that detoxified the metals was broader than that of EDTA. Stimulation of enzyme activity by EDTA could complicate interpretation of test data, a problem not shared

ISSN:0730-7268    

DOI:10.1002/etc.5620140202

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWater and foam samples from five streams in eastern Tennessee were analyzed for lipid content, lipid‐class composition, and polychlorinated biphenyls (PCBs). Total lipid contents and lipid‐class compositions varied substantially among streams and between the water and foam fractions within streams. However, lipid contents in foams were always greater than in the water from the same site (up to 100‐fold). Major lipid classes in the water and foam samples were phospholipids, free fatty acids, and hydrocarbons; these lipid classes indicate the stream status with respect to viable microbial biomass, organic decay, and petroleum pollution, respectively. Concentrations of PCBs in stream‐water and foam samples were also measured, and a laboratory experiment using stream water, reconstituted natural foam, and Aroclor 1254 was conducted to assess partition ratios of PCBs for water and foam. The results of the field and laboratory studies showed that the foam concentrated PCBs (relative to the parent waters) by factors of up to 10. The concentration of biogenic lipids and lipophilic pollutants in natural foams may influence the downstream transport of pollutants and affect their bioavailability to stream or

ISSN:0730-7268    

DOI:10.1002/etc.5620140203

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThree forms of volatile sulfides (free hydrogen sulfide, acid‐volatile sulfides [AVS] and a new form, heat‐volatile sulfides [HVS]), were measured and their relationships discussed. Purging of some contaminated sediments with nitrogen at 22°C failed to remove all of the free H2S, even after 6 h. With freshly H2S‐spiked uncontaminated sediment, purging of H2S was complete after 2 h; however, if the spiked sediment was allowed to stand for 53 d, H2S continued to be purged, even after 43 h. The H2S likely originates from equilibrium reactions involving reduced sulfur species in the sediment. Uncontaminated sediment spiked with H2S was found to be highly toxic using a sediment‐contact bioassay employingPhotobacterium phosphoreum. Addition of Fe3+, which sequesters the S2−, reduced the toxicity. Two other bioassays (ATP‐TOX and Toxi‐Chromotest), both involving a DMSO/methanol extract of the spiked sediment, showed greatest toxicity with spiked sediment that had been standing for 22 d. The results indicate that reduced sulfur species in sediment may be a cause of toxicity observed in contaminated an

ISSN:0730-7268    

DOI:10.1002/etc.5620140204

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractMultivariate quantitative structure‐biodegradability relationships (QSBRs) were developed for a series of 20 halogenated aliphatic hydrocarbons investigated for their microbial biodehalogenation (expressed as half‐lives). These QSBRs are based on a battery of quantum‐chemical descriptors and the use of the multivariate data analytical techniques principal component analysis (PCA) and partial least‐squares projections to latent structures (PLS). The developed models are introduced and discussed from a multivariate data analytical perspective, and much emphasis is placed on the elucidation of the predictive significance of the developed relationships. It is shown that multivariate QSBRs can be formulated for three sets of microorganisms and compounds. These QSBRs can be used to predict biodehalogenation properties for yet untested co

ISSN:0730-7268    

DOI:10.1002/etc.5620140205

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe influence of incomplete separation of water and sediment in batch sorption experiments was investigated with five chlorinated benzenes (sediment/water ratios between 0.25 and 50 g/L). Only the sorption coefficients of the most hydrophobic chemical, hexachlorobenzene, decreased with increasing sediment/water ratios. This decrease is assumed to be caused by an increasing amount of sediment that was not separated from the aqueous phase. To quantify this incomplete water/sediment separation, the unseparated sediment fraction, called thethird phase, was analyzed in suspension water. For this purpose the apparent enhanced solubilities of hexachlorobenzene and two polychlorinated biphenyls were determined in the suspension water. Solubilities of these compounds were found to be considerably enhanced (up to about 8 times). In addition, turbidity, dry weight, and dissolved organic carbon (DOC) measurements were used to quantify the third phase. On the basis of these third‐phase analyses, experimental sorption coefficients of hexachlorobenzene were corrected for third‐phase influence, where the apparent solubility measurements were the most success

ISSN:0730-7268    

DOI:10.1002/etc.5620140206

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe interactions of methyl, tetramethylene, and propyl sulfoxides and propyl sulfone during sorption onto four dewaxed, acid‐form peats have been studied by means of swelling measurements. The results for sulfoxides are displayed as heteromolecular sorption isotherms, which plot amount sorbed versus S=O group activity (molar density ratio relative to methyl sulfoxide). The present swelling data are compared to previous data for a homologous series of alcohols. Propyl sulfone apparently reacted with the peats during the sorption process, and one peat (Canadian) exhibited a dramatic 26% shrinkage in volume when exposed to this reagent for 8 weeks. Pyrolysis‐GC‐MS study of sulfone‐doped Canadian peat found that propyl sulfide was the predominant pyrolysis product, although traces of propyl sulfoxide and sulfur dioxide were als

ISSN:0730-7268    

DOI:10.1002/etc.5620140207

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSecond‐order rate constants were developed for the biotransformation of the herbicides atrazine and alachlor under aerobic, nitrate‐reducing, sulfate‐reducing, and methanogenic conditions. Batch‐reactor techniques were used, with seed cultures taken from acclimated biofilm columns. The reactors were fed acetate as a primary substrate. Pesticide biotransformation appeared to depend upon the continued presence of the primary substrate, indicating co‐metabolic transformations. All four electron acceptor conditions tested resulted in some biotransformation of both pesticides. Rate constants for alachlor ranged from 6.25 × 10−5to 1.60 × 10−4L/mg volatile suspended solids (VSS)·h, with the highest rate constant occurring under sulfate‐reducing conditions, and the lowest under methanogenic conditions. Rate constants for atrazine ranged from 1.04 × 10−5to 3.32 × 10−5L/mg VSS·h, although differences among the four electron acceptor conditions were not

ISSN:0730-7268    

DOI:10.1002/etc.5620140208

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractLittle information is available concerning the effect of salinity adjustment on effluent storage and toxicity identification evaluation (TIE) performance. These factors are important for accurate assessments of potential toxicity to marine organisms. The objective of this study was to determine (a) the effect of salinity adjustment (to 30 ppt), using hypersaline brine (100 ppt), on the toxicity of effluents stored up to 40 d, and (b) to determine the effect of salinity adjustment on TIE manipulations. Changes in effluent toxicity over time were examined by using a municipal and an industrial effluent. A toxicity time series was performed for 16 d for the industrial effluent and 40 d for the municipal effluent. Toxicity was measured with modified 48‐h acuteMysidopsis bahiaandMenidia beryllinatests Results indicate that, compared to day 0 test results, effluent stored with brine had fewer significant changes in toxicity than did effluent stored without brine To determine the effects of brine addition on TIE manipulations, we conducted a series of manipulations in which one aliquot of an effluent had brine added prior to the TIE manipulations and the other aliquot had brine added after the TIE manipulation The manipulations conducted were EDTA addition, sodium thiosulfate addition, C18extraction, aeration, filtration, and graduated pH manipulations Toxicity was measured with the modified 48‐h acute mysid test. Addition of brine had no effect on the outcome of TIE manipulations. We have concluded that it is operationally easier to add brine as soon as possible after sampling and that effluent tests should be conducted as soon as pract

ISSN:0730-7268    

DOI:10.1002/etc.5620140209

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe compound 2,6‐di‐tert‐butyl‐4‐nitrophenol (DBNP), a potentially powerful uncoupler of ATP‐generating oxidative phosphorylation, has been physically and spectroscopically characterized using X‐ray crystallography, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), GC‐MS spectrometry, Fourier‐transformed IR (FTIR) spectrophotometry, UV‐Vis spectrophotometry, and FT1H‐ and13C‐NMR spectroscopy. However, DBNP is not commercially available; therefore, it had to be synthesized in the laboratory prior to toxicity studies. The DBNP was prepared from 2,6‐di‐tert‐butylphenol (DBP) precursor in hexane through an electrophilic aromatic substitution process using NO2. A collective yield of 75% was obtained by using two empirically determined end points that prevented the coprecipitation of reaction by‐products and resulted in the formation of DBNP in high purity. Excessive amounts of NO2in reaction mixtures resulted in the decomposition of preformed DBNP. With a pKavalue of 6.8 and a higher degree of lipophilicity, DBNP may prove to be a stronger uncoupler of oxidative phosphorylation than 2,4‐dinitrophenol (pKa= 4.09) due to the expected enhancement of passive‐diffusion kinetics across biological membranes at the physiological pH of 7.4. The present study is intended to provide analytical toxicologists, industrial hygiene monitors, and other professionals involved in chemical health and safety with a comprehensive source of basic information on the synthes

ISSN:0730-7268    

DOI:10.1002/etc.5620140210

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY