摘要:

The toxicity of the fungicides zineb and nabam has been studied, using the persistent ship‐fouling diatomAmphora coffeaeformis. Growth and oxygen evolution/consumption studies showed that time was required for zineb to exert a toxic effect, suggesting that toxicity may be due to the degradation products 5,6‐dihydro‐3H‐imidazo (2,1‐c)‐1,2,4‐dithiazole‐3‐thione (DIDT) and ethylene diisothiocyanate (EDI). These were found to be more toxic than zineb and nabam, EDI being the most potent of the compounds tested.

ISSN:0892-7014    

DOI:10.1080/08927019009378150

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The allometric relationships between several size variables have been studied in population samples of the musselMytilus edulisfrom two offshore production platforms. Using these relationships, together with information on mussel packing densities available from the literature and previously documented data on the growth rates of these populations, it has been possible to predict the survivorship and potential biomass of mussels on one of these platforms, the Forties Bravo oil production platform in the northern North Sea. Through a process of self thinning, population density ought to decline rapidly during the first three years of colonisation when these mussels will be growing rapidly; beyond the third year population density should stabilise at a relatively constant level. Mussel biomass by contrast should increase steeply during the first six years of colonisation and growth but thereafter biomass curves should flatten out as terminal body size is approached. The predicted total biomass (shell + wet flesh weight) of subtidal ( — 25 m) mussels on this platform is substantially higher than that of mussels from mean low water mark. Standing crop (dry flesh weight) however, is significantly greater amongst the latter, perhaps indicating that feeding conditions are generally more favourable in the surface waters. The ability to predict mussel biomass from a single sample of the population could have industrial application both for assessing the potential impact of mussel fouling on platform stability and for establishing appropriate cleaning procedures for these structures.

ISSN:0892-7014    

DOI:10.1080/08927019009378151

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The surface charge onDesulfovibrio desulfuricansparticles grown in iron‐rich batch culture was monitored using electrophoretic mobility. Negative mobility was seen to tend towards zero as growth proceeded and this correlates with cell aggregation and the formation of a biofilm on a mild steel surface. Aggregate size can further be correlated with the relative amounts of sulphur and iron found in them. However, interference with this aggregation and surface treatments showed complex processes to be involved. Biofilm initiation was found to extend over a more lengthy period after batch growth had ceased and corrosion continued during this time. Whilst prevention of biofilm formation reduced corrosion, SRB biofilm formation and sulphide incorporation did not inevitably lead to corrosion, but was dependant on other factors such as biofilm consortia and oxygen availability.

ISSN:0892-7014    

DOI:10.1080/08927019009378152

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Biological activity in oil reservoirs can cause significant problems such as souring and plugging. This study focuses on the problem of polymer degradation and permeability reduction due to biofilm formation during polymer injection for improved oil recovery. Polymers are included in injection fluids to increase their viscosity. Results relating biological processes and polymer degradation to fluid‐dynamic conditions in a laboratory model porous medium are presented.

ISSN:0892-7014    

DOI:10.1080/08927019009378153

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

It is well known that ultrasonic baths are suitable for cleaning surfaces. In order to investigate the mechanisms of the cleaning effect a simple experimental arrangement with an adjustable ultrasonic transducer was developed. Reverse osmosis membrane samples colonised with a monolayer of fast adhering bacteria were exposed to defined ultrasound. A threshold for detachment was defined if more than 95% of the bacteria were removed. Detachment rate was found to depend on (i) the sound intensity (threshold 2 Watt), (ii) the time of exposure (60 s) and (iii) the distance between transducer and membrane (4 cm). The shear forces in the acoustic boundary layer are considered to be responsible for the detachment of the bacteria. The first results reveal that the application of ultrasonic waves provides a tool both for cleaning biofouled surfaces and for investigating the adhesion forces of microorganisms to surfaces.

ISSN:0892-7014    

DOI:10.1080/08927019009378154

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The effect of gravity on the deposition of wild‐type and flagellar mutants ofPseudomonas fluorescensandVibrio parahaemolyticuswas evaluated using computer image analysis. Rates of bacterial accumulation were determined for both the upper and lower surfaces of a glass flow cell with well‐defined laminar flow conditions. Wild‐type organisms deposited on upper and lower surfaces independent of gravity, whereas flagellar mutants deposited on lower surfaces at 10 to 40 times the rate of deposition to upper surfaces. The same gravitational effect was observed for marine communities, where 30% more marine bacteria were observed to deposit on lower surfaces than to upper surfaces, and also in recolonisation studies using motile and nonmotilePseudomonas fluorescens. These results are in contrast with earlier arguments that bacterial mass, density, and sedimentation are insignificant within flowing microenvironments. These results also showed that motility due to both polar(Pseudomonas sp.)and lateral flagella (Vibrio sp.)can be important in overcoming gravitational forces during cell deposition processes. Computer image analysis was also used to evaluate the orientation of the longest axis of the cells with the direction of flow. The longitudinal axis of most attached cells was aligned parallel to flow lamina. Alignment was observed in all strains studied, but was greatest for nonmotileP. fluorescensmutants. Gravity had no effect on the degree of alignment for either the wild‐type or mutant strains.

ISSN:0892-7014    

DOI:10.1080/08927019009378155

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0892-7014    

DOI:10.1080/08927019009378149

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor