Particle marine snow

Formation. Evidence that at least some of the marine snow particles are formed by coagulation has been accumulating. Sedimenting diatoms in a coastal Canadian bay have been observed to change the particle size spectra with depth in a manner consistent with coagulation of the settling particles (22). As already noted, the relatively small fractal dimensions of marine snow particles are consistent with their formation from coagulation processes. 

This relatively well-defined system facilitates laboratory experiments and theoretical simulations. The presence of marine snow particles composed of diatoms after diatom blooms implies that coagulation can occur rapidly in this... 

Fig. 2.8 Time series of mean marine snow concentration [kmolP/m3] (solid), number of aggregates [particles/cm3] (dashed), and the mean slope of the particle size distribution in the euphotic zone (solid), and number of aggregates (dashed) at 175W 55°S.

Marine snow Large, loosely aggregated solids composed of biogenous and Uthogenous particles. The organic material is often colonized by microbes. 

Scientists have observed that marine snow can be a nuisance. Because in some cases gas may be produced, particles nse and create a scum, and dns can be dried by the sun to produce a surface of sufficient strength to permit seagulls to walk upon it. Such scum extends for many thousands of acres (hectares) in the Adriatic Sea. where it has become a menace to fishermen and the tourist trade. Such scums were reported as early as the 1700s. 

Field studies point in a similar direction field comparisons of peptide hydrolysis rates and amino acid turnover in coastal sediments showed that amino acid production could exceed uptake by a factor of approximately 8 (Pantoja and Lee, 1999). A comparison of potential enzyme activities and sedimentary amino acid and carbohydrate inventories in sediments from the Ross Sea also showed that potential hydrolysis rates on time scales of hours should in theory rapidly deplete sedimentary amino acid and carbohydrate inventories (Fabiano and Danovaro, 1998). In deep-sea sediments, Poremba (1995) also found that potential enzyme activities in theory could exceed total sedimentary carbon input by a factor of 200. Finally, Smith et al. s (1992) investigation of potential hydrolysis rates and amino acid uptake in marine snow demonstrated that the particle-associated bacteria were potentially producing amino acids far in excess of their own carbon demand. 

In the redox zone the role of OM in the balance of oxidizers and reductants is very important. In fact, Rozanov [75] argued that OM is the main reduc-tant in the suboxic layer. Sorokin [23] explained that OM distributions in the redox zone were due to dense bacterial populations in detrital particles and marine snow. 

Alldredge A. L. and McGillivary P. (1991) The attachment probabilities of marine snow and their implications for particle coagulation in the ocean. Deep-Sea Res. 38, 431-443. 

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