DOM export

This major input of DOM from macrophytes is not restricted to lakes, but is also realized in other aquatic ecosystems. DOM export from watersheds in lotic ecosystems is directly related to annual runoff, but significantly greater in swamp-draining streams compared with upland-draining streams (Mulholland and Kuenzler, 1979 see Chapter 2 and 6). In the Hudson Estuary, planktonic bacterial production is 3 to 6 times greater than primary production (Findlay et al., 1992). DOC derived from submerged aquatic plants in part supports the difference in bacterial carbon uptake and planktonic primary production. 

HanseU et al. (2007) -0.4 X 10 2 2003 WOCE data. Calculated by mass balance of total excess N accumulation rates and estimated inputs by atmospheric deposition and DOM export... 

For terrestrial ecosystems, soil C N ratio was significantly correlated to DOM export (Aitkenhead and McDowell, 2000). At a global scale, mean soil C N ratio explained 99% of the variability in annual riverine DOC fluxes. 

Stedmon C.A, Markager, S., S0ndergaard, M., Vang, T., Laubel, A., Borch, N.H., and Windelin, A. (2006). Dissolved organic matter (DOM) export to a temperate estuary Seasonal variations and implications of land use. Estuaries Coasts, 29, 388- 00. 

Export of DOM into Deep Ocean and Horizontal Segregation... 

Fig. 1. Model depicting nitrogen flows in a kelp bed community. Primary production by macrophytes is partitioned into particulate (POM) and dissolved (DOM) components. Filter-feeders feed on detritus consisting of POM, bacteria and animal faeces. Recycling of nitrogen via the feedback loop provided by faeces is indicated by heavy lines. Fig. la) shows the model under downwelling conditions, when phytoplankton is imported with surface water from offshore. Fig. lb) shows the model under upwelling conditions when it is assumed that phytoplankton in the upwelling water is negligible and excess detritus is exported in surface water.

The nature and timing of DOM inputs influence both community organization and metabolism (see Chapter 15), which in turn affect DOM concentration and export at the ecosystem scale. The relationship of source heterogeneity to system function is one of the least studied aspects of DOM dynamics. For planktonic communities, source effects are direct and immediate. Attached communities also respond and adapt to local DOM inputs, but the capacity of biofilms to self-organize within a secreted polymer matrix... 

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