1887

Abstract

The NAME project is an European research project which gathers hydrogeologists, geophysicists, geochemists and marine biologists belonging to different institutions: • DHI Water & Environment, Denmark; • Netherlands Institute of Ecology, Netherlands; • Max Planck Institute, Deutschland; • Ribe County, Denmark; • Technical University of Denmark; • University of Lausanne, Switzerland. The role of nitrogen in eutrophication of coastal marine environments is well documented (Horwarth et al., 1996). It is also well known that the application of fertilizer on agricultural fields causes nitrate concentrations in groundwater to increase (Postma et al., 1991). The nitrate bearing-nutrient that enters the marine environment in this way is monitored by measuring their fluxes in outlets of rivers and estuaries. Furthermore a significant part of the nitrate is removed by denitrification in the estuarine system (Nixon, 1996). However, at extensive sections along the European coast, the groundwater is discharging directly into the sea by upward transport throw the sea bottom. The importance of this direct nutrient flux into the marine environment is virtually unknown both with respect to its quantitative importance and with respect to the processes that take place at the freshwater-seawater interface. Given the steady increase in groundwater nitrate concentrations (Howarth et al., 1996), there is a strong need to investigate and document this matter and to evaluate its significance for coastal zone management. To illustrate the potential significance of processes occurring at the freshwater-seawater interface for the impact of direct discharge of nitrate containing groundwater on the marine ecosystem, two imaginary end-member scenarios may be envisioned: • In the first scenario nitrate bearing groundwater emerges unaltered through vents in the sea bottom. In this case there is a direct input of nitrate into the marine environment which may seriously affect the state of eutrophication in the coastal marine ecosystem. • In the second scenario, the freshwater is thought to mix dispersively with seawater below the sea bottom and in this case the emerging nitrate is reduced to free nitrogen while oxidizing organic matter that is deposited from above. The two scenarios described above are purely speculative, basically because of our current ignorance concerning real world processes. A recent research interest in this subject has lead to some reports describing the seepage of groundwater through the sea bottom (Moore, 1999; Hussain et al., 1999; Bussman et al, 1999). Generally, however, the current literature reveals a disturbing lack of knowledge concerning the quantitative significance of nitrate-bearing groundwater directly discharging into the marine environment and the biogeochemical processes involved.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.201406186
2002-09-08
2020-11-23
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201406186
Loading
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error