摘要:

AbstractDibromochloropropane (DBCP) has been used to control nematodes since 1955 by pineapple growers in Hawaii, U.S.A. A major portion of the applied chemical eventually volatilizes to the atmosphere, but a residual amount adsorbed to soil particles may percolate downward with infiltrating water and become the source of groundwater contamination. Apart from volatilization, biodegradation is the only other means of loss of DBCP from soils. Although DBCP has been accepted as biologically stable, recent laboratory and field experiments indicate that it undergoes slow degradation in the presence of microorganisms. A numerical model was formulated and applied to simulate DBCP transport and transformation in soils. Relevant physicochemical and biological actions are incorporated in the model formulation. With values of other model parameters established independently, it was possible to evaluate the coefficients of DBCP biodegradation and adsorption by model calibration. The modeling results suggest the rate of biodegradation is greater in the top layer of the soil where the population of microorganisms is greater, and decreases as greater depths are reached. For two test fields on the island of Maui, the rate of degradation was found to be 0.00016/hr in the top 45 cm of soil, 0.00014/hr for a depth up to 90 cm, and 0.00006/hr for greater depths. The decrease of DBCP residual due to biodegradation was also found to depend on the adsorption of DBCP to soil particles. A high adsorption in the top layer of soil retards the movement of the pesticide and thus allow a significant biodegradation to take place.

ISSN:0884-8181    

DOI:10.1002/tox.2540020302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe effect of chromium addition on the green algaChlamydomonassp. was investigated. Experiments were conducted by culturing pure stock cultures of the algae in a synthetically prepared culture medium simulating wastewater. Doses of chromium with different concentrations were added in shock and continuous forms. The effect of these doses on the growth of the algae was evaluated by carrying out algal cell counts. Possible removal of chromium by algal accumulation of the chromium was also evaluated by measuring residual chromium concentrations in the effluent. The results indicated thatChlamydomanassp. could tolerate shock chromium doses of up to 0.2 mg. ℓ−1and continous doses of up to 0.25 mg. ℓ−1and can adapt to the presence of chromium in the medium. However, possible morphological changes could be induced in the cell. Furthermore,Chlamydomonassp. was found to remove about 20% of the chromium found in the

ISSN:0884-8181    

DOI:10.1002/tox.2540020303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA toxicity procedure has been developed and proposed for use in establishing acceptable initial loading rates and detoxification potentials for hazardous industrial waste when combined with soil. The procedure involves conducting toxicity screening and toxicity reduction experiments using selected waste‐soil combinations. These experiments employ a bacterial bioluminescence assay (MicrotoxTM) to determine acute toxicity of organic contaminants contained in the water soluble fraction (WSF) of waste‐soil mixtures. Toxicity screening test results are used to establish a range of loading rates acceptable for use in subsequent waste‐soil treatability studies. Toxicity reduction experimental results are used to determine soil detoxification potentials over time for soluble toxic organics contained in the waste‐soil loading combination selected. A major factor in determining acceptability of any test procedure is whether or not different investigators can achieve reproducible and comparable results. This paper describes the proposed procedure and reports results from toxicity experiments conducted concurrently by two laboratories using aliquots from the same soil and waste samples. Comparability of results was reported to be a function of the similarity of waste sample aliquots used in the toxicity experiments. Toxicity screening results for uniform technical grade creosote aliquots were highly comparable between the two laboratories, while results for highly variable creosote wood preserving waste (WPC) aliquots were much less comparable. Toxicity reduction experimental results for the WPC waste also indicated significant variation between laboratories for initial (Day 0) samples; however, the same patterns of detoxification over time were observed by each laboratory with toxicity results at the end of the experimental period (Day 42) being similar. Although the research described in this article has been funded wholly or in part by the U.S. Environmental Protection Agency, it has not been subjected to the agency's peer and administrative review and therefore may not necessarily reflect the views of the agency and no official endorsement should be i

ISSN:0884-8181    

DOI:10.1002/tox.2540020304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractSamples taken from an activated sludge reactor used for the biodegradation of metal cutting fluids were studied for the presence of plasmid‐containing bacteria. Twenty different bacterial isolates contained one or more plasmids. After numerous transfers of the isolates through LB broth, 55% of the plasmids were spontaneously lost as evidenced by agarose gel electrophoresis. Eighty percent of the isolates were resistant to one or more antibiotics, 65% resistant to two or more antibiotics, 40% resistant to three or more, 20% resistant to four or more and 5% resistant to five antibiotics. The isolates were also tested for their sensitivity to several common metals. This study has demonstrated that activated sludge is a natural reservoir for plasmid‐containing bacteria involved in biodegradation of was

ISSN:0884-8181    

DOI:10.1002/tox.2540020305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractPrevious experiments indicate that parathion, DDT, aldrin, and dieldrin induce changes in fatty acid and phospholipid composition inEscherichia coli. The effect of parathion on the growth and viability ofE. coli, P. aeruginosaandR. melilotiwas studied. When the pesticide was present at a concentration of 8.6 × 10−6M, the following effects were observed:P. aeruginosagrowth was not affected,E. coliwas slightly inhibited andR. melilotiwas affected adversely in the incubation mixture. We also examined the effects on the cell membrane components such as phospholipids and proteins; both quantitative and qualitative changes were observed. The results varied according to the microorganism utilized. Our data revealed alterations in the phospholipids that may be an important adaptative response of microorganism to growth in the presence of the pesticid

ISSN:0884-8181    

DOI:10.1002/tox.2540020306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThis review ofPhotobacterium phosphoreumtoxicity bioassay, commonly known as the MicrotoxTMtests, consists of two parts. The first part, I. Test Procedures and Applications, is a selective literature review which describes the principle, methodology, experimental conditions and procedures, and the applications of the MicrotoxTMtest. It includes a list of relevant references and tables showing comparisons of Microtox test results with those of various other acute toxicity assays for selected compounds and complex industrial effluents. The second part of this review deals with toxicity data compilation.

ISSN:0884-8181    

DOI:10.1002/tox.2540020307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe use of mediator assisted amperometric whole‐cell biosensors, monitoring microbial photosynthetic electron transfer, to screen for herbicides in intake protection by the water industry is described. Cells harvested from axenic cultures are loaded onto bacteriological filters and held against a working carbon electrode polarised against the silver chloride reference. Redox mediators are reduced by the microorganisms and then reoxidised at the working electrode resulting in a flow of current. For on‐line applications the sensors are controlled by a programmable electrochemical analyser (Artek) and housed in specially designed perspex flow cells which incorporate light emitting diodes (LEDs) for photosynthetic stimulation. A range of cyanobacteria and algae have been tested, but biosensors incorporating unicellular cyanobacteria have proven the most successful. Results obtained using the cyanobacteriumSynechococcusshow detection levels of less than 200 ppb with response times of less than ten minutes for selected herbicides. Sensor stability in the absence of pollutant poisoning has been found to be greatly influenced by the choice of mediator. Membrane penetrating mediators such as ‐benzoquinone reduce sensor life to about 24 hours, while a sensor life of up to six days has been achieved with ferricy

ISSN:0884-8181    

DOI:10.1002/tox.2540020308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe hazardous chemicals that have been released into the aquatic environment may disturb the balance of the aquatic ecosystem. Chemicals do not exist in single pure form, but occur in mixtures in the environment. Consequently, their effects on organisms living in the aquatic environment are primarily due to the combined toxicities. In this study, the interaction effects between chemicals such as copper, cadmium, chromium and pentachlorophenol on the growth of green algaeChlorella ellipsoidea, were investigated using a batch culture. Growth rate was a more sensitive index than standing crop at a given time for detecting the toxicity of chemicals. The EC50values obtained from dry weight, were higher than those obtained from ATP, chlorophyll‐a, chlorophyll‐b, carotenoid as growth indices for algal density. The toxicity of each chemical was dependent on the test period. The inhibition rate of PCP and Cu in comparison with the control for the exposure time of 24 hours was higher than that for the exposure time of 48 hours. The inhibition rate of Cr and Cd for 48 hours was higher than that for 24 hours. The toxic intensity of chemicals was, in order, PCP, Cu, and Cr, without exception. The toxicity of Cd was changeable depending upon the indices used. The method modified by Stratton (1983) and the isobologram method were used to determine the modes of interaction effects of the chemical combinations. These two methods led to the same results, with three exceptions. A synergistic effect was observed for combinations between Cr and PCP, between Cu and Cd, and between Cu and Cr; while an antagonistic effect was observed for combinations between Cd and PCP, between Cu and PCP, and between Cd and Cr within some concentration ran

ISSN:0884-8181    

DOI:10.1002/tox.2540020309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractWhen rapidly growing bacterial cells are exposed to low concentrations of toxicants, growth inhibition usually occurs. However, some toxicants not only inhibit bacterial growth but also affect the luciferase activity during ATP determinations. Thus, the observed light output reduction of a test bacterial system is the net result of both bacterial growth and luciferase inhibition. Based on this information, a new toxicity screening test was developed, the ATP‐TOX Syste

ISSN:0884-8181    

DOI:10.1002/tox.2540020310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0884-8181    

DOI:10.1002/tox.2540020311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY