Ice cover of the two Central European steppe lakes, Lake Balaton (Hungary) and Lake Neusiedl (Austria/Hungary), is characterized by high interannual variability (mean ice duration ± s.d.: 44±26 days and 73±28 days, respectively). For both lakes, a trend towards shorter ice duration and earlier ice-off can be observed in the 86 and 81 year data records, respectively. For Lake Neusiedl, significant trends for ice-on (+2.3 days decade −1 ), ice-off ( −1.8 days decade −1 ) and ice duration ( −3.1 day decade −1 ) are detected. At Lake Balaton, however, trends for ice-on (0 day decade −1 ), ice-off ( −0.7 days decade −1 ) and ice duration ( −1.2 days decade −1 ) are not significant. The temporal trends have accelerated for Lake Neusiedl in the past 60 years (ice duration −5.6 days decade −1 ). The variability of the ice parameters has increased during the 80 year observation period for Lake Neusiedl, but not for Lake Balaton. The number of melt-refreeze cycles at Lake Balaton increased at first, but then decreased during the last 20 years at both lakes.Warming trends in mean surface water temperatures for all seasons are more distinct than temporal trends of mean air temperatures. Increases of winter air temperature by 1°C are related to an ice-on delay, a decrease in ice duration (Lake Balaton: −12 days°C −1 , R 2 =0.72; Lake Neusiedl: −11 day°C −1 , R 2 =0.54) and an earlier ice-off. Snow cover, wind speed, and solar radiation are also related to ice dates.Mediterranean Oscillation and the North Atlantic Oscillation show significant relationships with ice phenology at both lakes whereas the East Atlantic teleconnection pattern only is related to ice characteristics of Lake Neusiedl.

Activated carbon fiber (ACF) was used as a model of commercial activated carbons to examine the effect of surface chemistry on the attachment behavior of bacterial biomass. Surface acidity was found to enhance the biomass-ACF interaction. When ACFs were applied as biomass support media in a continuous stirred tank reactor, surface acidity of the carbon resulted in faster biomass growth in the start-up phase. The start-up phase was simulated by a simple biomass attachment kinetics model. Experimental and calculated data show a reasonable agreement, with the exception of the hydrogenated specimen, which was interpreted by assuming that the hydrogen-reduced surface is highly reactive and then may undergo oxidation in the initial phase of operation so that the adsorption characteristics are altered.

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