摘要:

AbstractIn warm climates the control of aquatic snails as intermediate hosts of trematodes is very important for health. A biological control has been successful by a predatory snail (Marisa) as well as by reducing the aquatic vegetation. Of a greater importance, however, still is the chemical control by various molluscicides, especially by cholinesterase inhibitors (carbamates and organophosphorus compounds), which are active also in sublethal concentrations via the carbohydrate and protein metabolism. Of a special importance is also the application of synergistically active compounds, by which the biocidal activity is considerably increased, the required biocide concentration in the water is decisively reduced. Molluscicides of plant origin may be very important in future, especially the later of Euphorbiaceae and the natural products obtained from them which are active at high dilutions. Also the field of chemosterilants need to be explored.

ISSN:0323-4320    

DOI:10.1002/aheh.19880160202

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractA method of the statistical estimation of the threshold of “no effect” and “100% effect” levels of a test compound has been suggested. The experimental data of this method concern the survival of organisms exposed to a range of concentration of toxic ch

ISSN:0323-4320    

DOI:10.1002/aheh.19880160203

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe spatial and seasonal distribution of the viable heterotrophic population and three heterotrophic physiological groups, i.e. ammonifyers, nitrate reducers and sulphate reducers, were studied in two reservoirs in the province of Vizcaya (Spain). Using indicative parameters, both reservoirs were classified as warm monomictics, one hypereutrophic and the other mesotrophic. A direct relation between the size of the bacterial populations and the trophic levels of the reservoirs was observed. Likewise, the distributions of the bacterial populations in the water column are basically different. In the hypereutrophic lake there is a direct relationship between the bacterial distribution and the physical‐chemical environment of the reservoir that cannot be observed in the mesotrophic lak

ISSN:0323-4320    

DOI:10.1002/aheh.19880160204

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractDenitrification is studied in sediments from two areas of the River Butrón which represent different situations with respect to their degree of pollution. Denitrification is analysed by means of the following parameters: maximum denitrification rate (Vmax), Michaelis constant (Km), denitrification rate (v), denitrification constant (kd) and number of denitrifiers. In all the samples analysed denitrification follows a kinetic type Michaelis‐Menten with respect to nitrate.Vmax,Kmand number of denitrifiers are clearly superior in the polluted area when compared to the cleaner area, indicating an advantage given that denitrification suggests an alternative pathway for breaking down organic matter with low levels of dissolved oxygen. By comparison betweenKmand natural nitrate concentration values we find thatvfollows a first order kinetic depending directly on the nitrate concentration.valso presents higher values in the area of the river where the entry of sewage is taking place than in the cleaner area. However, this difference does not have a kinetic origin but rather is given by different nitrate concentrations in their sediments. This is due to the fact that the two areas present similar efficiencies in the elimination of nitrate, which is deduced from the similar values of

ISSN:0323-4320    

DOI:10.1002/aheh.19880160205

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe role of the benthic ciliofauna of the Tsibulnik bay of the Kremenchug reservoir in the comsumption of the primary production of phytomicrobenthos and the destruction of organic Substances is shown. In July all over the buy ciliates had consumed 41 % of the benthic primary production. During the process, consumption rates had reached 1.34 kJ/m2d on seperate sections of the bottom. Sufficiently high is the role of these protists in the destruction of organic substances. They had destroyed 1.4… 1.5% of the whole mineralised organic substances in summer and 10… 11% in autumn. The authors made a conclusion on the importance of the benthic ciliofauna in the transformation of organic substances in an eutrophic

ISSN:0323-4320    

DOI:10.1002/aheh.19880160206

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractFor 113 species of Oligochaeta living in Europaean freshwaters data on the saprobic valence, the indicative weight of species and the individual saprobic index were given. The big majority of Oligochaeta is hardly determinable and needs special morphological and anatomical studies. The few easily recognizable species were figured. Oligochaeta show a relatively wide ecological valence so that their application for determining the degree of saprobity should be coupled with the specific determination of the other members of the benthic community.

ISSN:0323-4320    

DOI:10.1002/aheh.19880160207

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractAccording to an investigation of an anaerobic sewage pond in the State of Mexico we are proposing the change of the saprobic valence and other saprobiological characteristics for three species of mixotrophicEuglena, i.e.E. viridis(O. F. MÜLLER) EHRENBERG, D.agilisH. J. CARTERandE. proximaDANGEARD

ISSN:0323-4320    

DOI:10.1002/aheh.19880160208

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractFish,Cyprinus carpioandChanna punctatusin four sizes (6.0 ± 1.2; 12.5 ± 1.6; 20.6 ± 1.5 and 28.0 ± 1.8 cm in total length) were exposed to industrial effluents from the Sangam Dyeing Factory (Ludhiana), the Sterling Steel and ABC Paper Mills (Hoshiarpur) to evaluate the acute toxicity of these effluents at different fish sizes. Results reveal that the toxicity of industrial effluents decreased with the increased fish size from 6.0 ± 1.2 to 20.6 ± 1.5 cm in length. However, for specimens of the size of 28.0 ± 1.6 cm and more, the toxicity of the effluents increased with an increase in fish size. On the basis of the relative toxicity to fish, effluent from the Sterling Steel Mill was found to be highly toxic to fish and effluent from the Dyeing Factory least toxic except for the fish of 6.0 ± 1.2 cm at which dyeing factory effluent was most toxic and ABC paper mill effluent the leas

ISSN:0323-4320    

DOI:10.1002/aheh.19880160209

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe sorption of Co(II)., Mn(II)‐ and Fe(II)‐ions from aqueous solution on three power plant ashes was investigated in dependence on pH‐value and solution concentration. Sorption increases with rising pH‐value and increasing solution concentration. The results can be interpreted with the pH‐dependent occurrence of the hydrolysis products of the metal ions in solution and their reaction with the

ISSN:0323-4320    

DOI:10.1002/aheh.19880160210

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

ISSN:0323-4320    

DOI:10.1002/aheh.19880160211

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY