The near coast can be sites of active processing of carbon and nutrients.  They are often also highly productive systems.  My group looks at the cycling of carbon and nutrients in estuaries and the near coast.  Included in this research is the role of salt marshes in nutrient and carbon uptake and outwelling.  Pictures coastala-c.

https://sites.google.com/site/ctsaltmarshes/
http://ecosystems.mbl.edu/pie/

Aufdenkampe, A. K., E. Mayorga, P. A. Raymond, J. M. Melack, S. C. Doney, S. R. Alin, R. E. Aalto, and K. Yoo (2011), Rivering coupling of biogeochemical cycles between land, oceans and atmosphere, Front. Ecol. Environ., 9(1), 23-60.

Griffith, D. R., and P. A. Raymond (2011), Multiple-source heterotrophy fueled by aged organic carbon in an urbanized estuary, Marine Chemistry, 124, 14-22.

Raymond, P. A., and C. S. Hopkinson (2003), Ecosystem modulation of dissolved carbon age in a temperate marsh-dominated estuary, Ecosystems, 6(7), 694-705.

Zappa, C. J., W. R. McGillis, P. A. Raymond, J. B. Edson, E. J. Hintsa, H. J. Zemmelink, J. W. H. Dacey, and D. T. Ho (2007), Environmental turbulent mixing controls on air-water gas exchange in marine and aquatic systems, Geophysical Research Letters, 34(10).