摘要:

AbstractThe precipitation of calcite from a calcium bicarbonate solution, similar in ionic strength to natural hardwaters, was observed in a series of experiments utilizing an automated culture apparatus. Seeded growth experiments, using calcite seed crystals, were performed at a range of phosphate concentrations to observe inhibitory effects. These experiments demonstrated a linear relationship of increasing inhibition with increasing initial phosphate concentration. A further series of experiments was performed in which an actively photosynthesizing culture of a unicellular green alga (Chlorococcumsp.) was added to the culture vessel in order to initiate precipitation. Experiments to observe spontaneous precipitation, occurring in the absence of both seed and alga additions, were carried out to compare with precipitation rates in the algal experiments. A control experiment was also performed to investigate whether precipitation occurrred in algal cultures maintained in darkness. The carbonate site mechanistic model, developed for calcite precipitation in abiotic conditions, was used to analyse the results of the algal experiments and found to be applicable.

ISSN:0020-9309    

DOI:10.1002/iroh.19950800302

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19950800303

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

摘要:

AbstractThe annual average degree of phosphorus retention (bothTPandOP) in reservoirs was found to depend mainly on the theoretical retention time (RT). The phosphorus retention (RP) is shown for some reservoirs in Czech Republic to be well approximated (standard deviation = 10.9) withRP(TP)= 74.7* (1‐exp(‐0.0255*RT)) (N = 38, 7 ≤RT≤ 604 days).The inclusion of 13 additional reservoirs for which data were assembled from literature resulted in an almost identical relationship:RP(TP)= 76.1* (1‐exp(‐0.0282*RT)) (N = 51, range ofRTnearly unchanged).The retention of soluble reactive phosphorusRP(OP)studied on data from literature seems to be higher than that ofTP.Statistical comparison with data forRP(TP)of lakes has shown a significantly lower retention in lakes than in reservoirs for comparableRP, resulting inRP(TP)= 66.0* (1‐exp(‐0.00419*RT)) (N = 59, 5.8 ≤RT≤ 260000 days).The differences betweenRP(OP)andRP(TP)and differentiation of lakes and reservoirs are discussed and a need for more thorough theoretical analysis stressed. Consequences for watershed manage

ISSN:0020-9309    

DOI:10.1002/iroh.19950800304

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19950800305

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

摘要:

AbstractFactor analysis was used to identify the processes responsible for the changes in water quality in a stratified wastewater reservoir. These reservoirs are well suited to study hypertrophic conditions. In the epilimnion, the main source of variablility was the external loading due to variations in wastewater inputs and water level (volume) of the reservoir. The second source was the seasonal climatic changes affecting photosynthesis. The third source was differences between night and day processes affecting REDOX potential. In the hypolimnion, the main source of variability was organic loading but due to both external loading (wastewater inputs) and internal loading (compounds released from the sediments). The second source was related to the input of chlorophyll into the hypolimnion, which were external (entry of chlorophyll rich inflow from a waste stabilization pond) and/or internal (input of chlorophyll from upper layers due to water column mixing).

ISSN:0020-9309    

DOI:10.1002/iroh.19950800306

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

摘要:

AbstractThe widely distributedBrachionus calycifloruswas studied for morphological variation based on material from all tropical areas. The subspeciesB. calyciflorus borgertiApstein is redescribed and its subspecific status affirmed. Various forms with local distributions were noted and described and the morphological differences are attributed to a variety of possible factors. From the distribution patterns it is clear that rotifers are governed by the general principles that apply to other invertebrates and are not cosmopolitan. There are evidently dispersal centres forBrachionus calyciflorusand its subspeciesborgerti.

ISSN:0020-9309    

DOI:10.1002/iroh.19950800307

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

ISSN:0020-9309    

DOI:10.1002/iroh.19950800308

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the Modrac Reservoir, loaded with coal separation suspended material, rapid development of the zebra mussel (Dreissena polymorpha) took place from at least 1987. It is probably the first distinguished “infection” for this part of Balkan Peninsula, caused by this organism. Horizontal and vertical distribution of this mussel, at 15 different reservoir profiles, had been investiga

ISSN:0020-9309    

DOI:10.1002/iroh.19950800309

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

摘要:

AbstractThe interstitial stygobiont distributions of two rivers in the western High Atlas is analyzed in relation with sediment granulometry. Sixteen stations were sampled along the rivers N'Fis and Zat and their tributaries. Granulometry analyses were performed. Three grain size sediment types constitute the subterranean biotopes and reflect the local hydrodynamical conditions. The main rivers stations, which undergo frequent natural or human disturbances, are characterized by a high content of fine sediment; in contrast, tributaries stations show coarse and well‐classified sediments due to more stable biotopes and more regular hydrological conditions. The 92 taxa group 28 stygobiontic species with 11 crustaceans species. PCA. based on 16 stations, three faunistic richness indexes and three granulometric factors display a high correlation between coarse grain‐size content and the richness of stygobiontic taxa. A high silt content both limits the interstitial taxa and excludes crustaceans that occur only in coarse gravels. The granulometric preferenda in the species of the amphipod genusMetacrangonyxand isopodsMicrocerberus.MicrocharonandTyphlocirolanaare shown on Shepard triangular diagrams. Cohabitation of several species of the same genus could be explained by the occupancy of different ecological niches resulting from the grain‐size propo

ISSN:0020-9309    

DOI:10.1002/iroh.19950800310

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY

摘要:

AbstractNumbers of luminous bacteria were counted at three stations of the brackish water ecosystem of the western Baltic Sea from July 1985 to July 1986. Additional samples were taken during three cruises from stations at the North Atlantic Ocean, the Norwegian Sea and adjacent marine areas. — In Kiel Bight (western Baltic) values varied between 0 and 68,000 luminous cfu 1−1. With exception of the coastal station a distinct seasonal distribution pattern was shown in a water depth of 20 m: high numbers found in summer were opposed to low numbers in winter, the peaks being rather high in comparison to those of other areas. Statistical analysis showed that the results of 20 m were significantly different from those of 0 and 10 m depth; however, there was no correlation with temperature and salinity. Taxonomic studies revealed that the population consisted primarily of the genusPhotobacterium.— The optimum of salinity was not a brackish but a marine one and was about 30% for the majority of the strains tested. A smaller number of strains grew best at a salinity between 10 and 15%. Optima of temperature ranged from 15 to 20 °C for most of the test strains. — Taxonomic analysis was also performed with luminous strains from marine areas adjacent to the western Baltic Sea,Photobacteriumbeing the dominant genus here, too. Luminous bacteria were also enriched from the external surface and the gut contents of whitings (Merlangius merlangus) and cods (Gadus morhua). A model is proposed which explains the distribution pattern found. According to this, the gut‐dwelling luminous bacteria are transported by their hosts from the North Sea into the western Baltic Sea. Here they are released into the environment, thus inhabiting ano

ISSN:0020-9309    

DOI:10.1002/iroh.19950800311

出版商:Akademie Verlag, Berlin    

年代:1995

数据来源: WILEY