Salt marshes groundwater inputs

Rama, and Moore, W.S. (1996) Using radium quartet for evaluating groundwater input and water exchange in salt marshes. Geochim. Cosmochim. Acta 60, 4645-4652. 

At regional scales, there are also examples in which SGD of nitrogen equals or exceeds river fluxes. For example, DIN fluxes in groundwater discharges through salt marshes along the South Carolina coast are estimated to be equivalent to input from major rivers in this region ( 60 X 10 mol yr ) (Krest et ai, 2000) (Table 9.5). 

There is tremendous geographic variability in the spatial orientation and connections of salt marshes within estuaries and of estuaries with adjacent uplands and the ocean (Fig. 22.1). This paper focuses on the salt marsh ecosystem and associated tidal creeks and not the larger estuarine ecosystem, which may include deeper and extensive bays and sounds. However, it should be recognized that some marshes, especially those that do not have freshwater inputs from rivers, have no true open estuarine area and directly exchange with the ocean. Salt marshes are linked to adjacent terrestrial environments through water and material inputs from rivers, groundwater and precipitation. In cases where the majority of these inputs first pass though the open... 

Inputs, outputs and exchanges of N with systems adjacent to salt marshes are generally much smaller in magnitude than internal fluxes (Table 22.7). The source and relative importance of various external inputs of N to salt marshes varies from system to system. While the input of N from rivers is potentially large, most of this N is probably not taken up by salt marshes but is processed in aquatic portions of estuaries or routed to the open ocean. On average, the largest input is from N fixation (2-15 g N m year ), followed by atmospheric deposition (0.5-2.2 g N year ). Groundwater inputs are a major source of N in some smaller salt marshes with developed uplands such as found in the northeastern United States. 

Valiela, I., Teal,., Volkmann, S., Shafer, D., and Carpenter, E. (1978). Nutrient and particulate flrrxes in a salt marsh ecosystems Tidal exchanges and inputs by precipitation and groundwater. LimnoL Oceanogr. 23, 798-812. 

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