Chemical modelling applications to experimental recirculating streams

Abstract

Chemical models describing the precipitation of calcium carbonate

The Use of Microelectrodes to Study the Precipitation of Calcite upon Algal Biofilms

“…The flux of total calcium was calculated by Eq. [4] using the limiting concentration gradient at the biofilm surface assuming steady-state conditions above the biofilm. DC is the predicted change in total calcium concentration and was calculated using Eq.…”

“…Examination of the micrographs combined with the esti- [4]. It is also interesting to note that profiles of P CO 2 , [Ca T ], mate of calcium fluxes given in Table 2 permits a calculation of the precipitation rates, normalized with respect to the and SI for experiments 1 and 2 are similar in shape, although the precipitation rates in experiment 1 are higher, as shown crystal surface areas.…”

“…This rate is of the same order of magnitude as the precipitation rate measured in seeded measured immediately adjacent to the surface using Eq. [4], are shown in Table 2. As mentioned above, experiment 3 growth experiments (27) at a similar degree of supersaturation with respect to calcite.…”

The chalk-stream environment

“…Coprecipitation of phosphorus also occurs in these circumstances (House, 1990). Such degassing can occur across the air-water interface under conditions of severe turbulence and this can prove a problem when water is being recirculated in experimental systems (House et al, 1986;House et al, 1988). It can also occur in the relatively static flow conditions that develop in large macrophyte beds where CO, is taken out of solution by the photosynthetic activity of the plants (Howard et al, 1984).…”

The water quality of the River Dun and the Kennet and Avon Canal

“…The DO concentration changes with time in the flume, which were measured after the sediment disturbance, were analysed using a mass-balance approach. This included a calculation of the invasion of oxygen from the atmosphere to the water using the mathematical methods described previously for large scale recirculation streams (House et al, 1988). The mass balance was calculated using a FORTRAN program to produce a residual, the amount of oxygen consumed by the sediment (suspended and bed) and disturbed porewater.…”