Marine environments sorption processes

The presence of suspended solid materials increases the extent of LAS biodegradation [13,28], but the rate of the process remains invariable. The influence of the particulate material is due specifically to the increased density of the microbiota associated with sediments. However, suspended solids may also reduce the bioavailability of IAS as a result of its sorption onto preferential sites (e.g. clays, humic acids), although this is a secondary effect due to the reversibility of the sorption process. Salinity does not affect IAS degradation directly, but could also reduce LAS bioavailability by reducing the solubility of this molecule [5], Another relevant factor to be taken into account is that biodegradation processes in the marine environment could be limited by the concentration of nutrients, especially of phosphorus and nitrogen [34],... 

The partition coefficients for different LAS homologues (Table 5.4.2) are higher in the marine environment due to the higher ionic strength that promotes sorption of anionic surfactants [14] and an increase in the partition coefficient with the alkylic chain length has been observed (Table 5.4.2). The evolution of the concentration of the various homologues of LAS in solids in suspension (cf. Fig. 5.4.2) is similar to that found in water and, in the process of adsorption, an increase can be observed in line with the chain length, as commented on previously. 

Coupled Iron-phosphorus Cycling. The affinity of phosphate for sorptive association with ferric oxide and oxyhydroxide phases, well documented in soil and freshwater systems (see Sections 8.13.3.1 and 8.13.3.2), is also a well-studied process in marine systems. Three distinct marine environments where coupled iron-phosphorus cycling has been identified as an important process are MOR systems, estuaries, and continental margin sediments. The purely physicochemical process of sorption is essentially the same in these three distinct environments, where an initial, rapid surface sorption phase is followed, given enough time, by a redistribution of adsorbed phosphate into the interior of iron oxyhydroxides by solid-state diffusion (Bolan et al., 1985 ... 

The biogeochemical processes that generally describe the interaction of elements with particles are quite well known dissolution, flocculation, ion exchange, sorption, (co)precipitation, electron transfer, and biological uptake. In aquatic environments these reactions often occur simultaneously and competitively. In order to utilize marine tracers effectively, we must understand how elements are associated with particles and sediments. 

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