摘要:

AbstractTwoPseudomonas spp.were isolated from freshwater sediment by enrichment in nutrient broth amended with either 1000 μg/mL lead or tin. Both organisms also displayed multiple antiobiotic resistance. The tin‐resistant pseudomonad was also resistant to 1000 μg/mL lead, whereas the Iead‐resistantPseudomonas sp.was not resistant to 1000 μg/mL tin. Vertical and horizontal agarose gel electrophoresis of cleared cell lysates revealed that plasmids were not present in either strain. It therefore appears that lead, tin, and antiobiotic resistance is not plasmid encoded in these org

ISSN:0884-8181    

DOI:10.1002/tox.2540020402

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

年代:1987

数据来源: WILEY

摘要:

AbstractCadmium is always found in association with zinc. However, zinc is an essential micronutrient in living cells, whereas cadmium has no known useful biological function. In fact, cadmium is ranked among the most hazardous trace elements in the environment and is highly toxic to all components of aquatic communities. Cadmium in soils seems tightly held and is not readily removed by leaching, and consequently, cadmium in freshwaters is mostly connected with human activities. The concentration of Cd in natural waters is usually less than 1 μg. L−1but the values vary greatly among localities; the highest concentrations of cadmium have been observed in areas with acid mine drainage. The important mechanism of toxic action of Cd on algae and cyanobacteria is thought to be the „poisoning”︁ of enzymes, but many other toxic actions are known. A variety of environmental factors are known to modify the toxicity of cadmium. It is very difficult to allow for all of these factors simultaneously to predict the effect that a given amount of a metal will have on a given algal population. Uptake of Cd and other heavy metals to produce an internal concentration than in the external environment appears widespread in algae and cyano

ISSN:0884-8181    

DOI:10.1002/tox.2540020403

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

年代:1987

数据来源: WILEY

摘要:

AbstractMicrocosm toxicity tests using naturally derived protozoan communities were used to estimate permissible concentrations of copper. In tests with copper sulfate, taxonomic richness of communities was adversely affected at concentrations ≧12.7 μg/L after 21 days. Colonization was also affected at ≧12.7 μg Cu/L. Concentrations affecting taxonomic composition, chlorophyll and biomass concentrations, and nutrient retention ranged from ≦6.6 to ≧59.5 μg Cu/L. A Cu concentration expected to affect only 5% of taxa (EC05) adversely was predicted from test data as 3.2 (1.6–4.8) μg Cu/L. A similar estimate of a 5% effect level based on single‐species chronic toxicity test data was 4.9 (2.2ndash;7.1) μg Cu/L. Results of a test with combined effluents containing Cu were similar, with differences in colonization apparent at ≧18.0 μg Cu/L. Reductions in individual populations were apparent at 8.7 μg Cu/L. Estimates of permissible concentrations derived from these tests were reasonable when compared to the revised numerical water quality criteria (8.2 μg Cu/L at a hardness of 65 ppm). In addition, they fell above selected literature reports of Cu levels in clean systems (23 μg/L), thus seeming to be a reasonable basis f

ISSN:0884-8181    

DOI:10.1002/tox.2540020404

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

年代:1987

数据来源: WILEY

摘要:

AbstractEnergy and cell membrane ATPase‐dependent H+efflux from yeast cells was inhibited by heavy metals, which also inhibited energy‐dependent K+uptake by the cells. Heavy metals also induced K+efflux from metabolizing cells in two phases: reversibly at low concentrations and irreversibly at high concentrations. The concentration dependence of all of these effects varied considerably between metals.The effect ofin vivoinhibition of H+transporting ATPases on cell membrane polarization and thus on cellular transport processes, including heavy metal uptake, are discussed. It is proposed that the inhibition of H+efflux and the appearance of irreversible K+efflux in yeast are potentially useful indicators of heavy metal toxicity toward yeast and possibly other fu

ISSN:0884-8181    

DOI:10.1002/tox.2540020405

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe Microtox test uses the marine luminescent bacterium,Photobacterium phosphoreum. To provide the organism with osmotic protection, sodium chloride (2.0%) is usually added to freshwater samples before analysis. This procedure is shown to cause a dramatic lowering of measured toxicity where ionic compounds are the major toxicants present. The reason for this is the consequent variation in ionic strength upon addition of NaCl rather than formation of less‐toxic chloro complexes. Data are given for the toxicants Zn, Cd, Cu, NH4+, and phenol.It was found that measurements on aqueous samples could be made without adjustment provided that the salinity was in the range of 1.0–7.0%. Freshwaters can also be analyzed without adjustment of ionic strength by adding sucrose (20.4%) to provide the necessary osmotic protection.It is therefore recommended that the ionic strength of aqueous samples should not be altered as part of the test and that receiving waters should be used as the diluent wherever possi

ISSN:0884-8181    

DOI:10.1002/tox.2540020406

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.2540020407

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.2540020408

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.2540020409

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.2540020401

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

年代:1987

数据来源: WILEY