From marsh plants

DMSP is present in a number of marsh plants, but only in Spartina altemiflora (191 and S. anglica (221 is it particularly abundant. Spartina altemiflom is the dominant species in temperate marshes of North America but not in marshes or wetlands at lower latitudes. To date, most DMS emission measurements have been made in marshes dominated by S. altemiflora. Emission rates in areas having other marsh grasses, with lower DMSP content, are likely to be considerably lower. Estimates of DMS emission from saltmarshes in general which are based on fluxes from S. altemiflora without considering the species of grass are likely to be considerably overestimated. 

Differential metal concentrations in tissues or organs, as well as the growth rates and production of sea grasses78 and salt marsh plants,81 have been used to calculate the potential cycling/turnover of metals within a system and/or the annual export of contaminants from an estuarine environment to adjacent coastal waters. Similar studies have been performed for macroalgae23 and have provided valuable information on contaminant transport and bioavailability processes within and between aquatic ecosystems, since contaminants associated with decaying plant biomasses will become bio-available through herbivory or the detritivore food web. 

In the leaching phase, soluble compounds are rapidly lost from fresh detritus over a scale of minutes to weeks (figure 8.15 Wilson et al., 1986). In the case of the marsh plant 5. altemiflora, as much as 20 to 60% of the original material can be lost during this phase (Wilson et al., 1986). These soluble DOM compounds released from detrital particles are rapidly used by a high abundance of free bacteria in the surrounding water column (Aneiso et al., 2003). Much of this leached material likely consists of short-chain carbohydrates, proteins, and fatty acids (Dunstan et al., 1994 Harvey et al., 1995). 

The release of H2S from marsh sediments predominantly occurs across nonvegetated sediments and is controlled by anaerobic decomposition processes. Conversely, DMS is controlled more by the distribution of DMSP in plants and their associated physiology. 

Short-chain fatty acids fatty acids thought to be derived from aquatic sources (C12-C18) to others (C44-C18) from multi-sources (zooplankton, bacteria, and benthic animal and marsh plants). 

The turnover of N in marsh plant fitter is difficult to determine because of the immobilization that occurs during decomposition. Carbon loss cannot be used as a proxy for N turnover because C and N decomposition are decoupled and C is also immobilized during decomposition (Tremblay and Benner, 2006). Based on the decrease in mass of N-labeled detritus from the White and Howes experiment (1994b), we calculate N turnover rates to exceed C during the leaching phase of... 

Mass balance and isotopic tracer approaches have been used to quantify N fluxes associated with marsh plant growth and death. One study in a very productive, medium form of S. alterniflora from a Georgia salt marsh shows that total uptake of N by roots of S. alterniflora was 34.8 g N m year. Of this 43% was lost by death or leaching from aboveground plant parts, while the rest was lost by death of roots and rhizomes. Total transfer of N from below-to aboveground tissues was 33 g N m ... 

Zizaniopsis is a fresh marsh plant and is included by way of comparison to illustrate the potential importance of N availability in controlling recycling efficiency, seen here as the profligate leaching of N from dead Zizaniopsis. Units—g N m year ... 

---