again (Fisher and Matisoff, 1982) as a result of additional nutrient 

 loading. 



Similarly, between 1850 and 1950, the nitrogen content of the Rhine 

 River had only increased perhaps two-fold to ~100 yg-at N € , with a 

 second doubling by 1970. Over just the last decade, it has doubled 

 again to ~400 yg-at IU (Van Bennekon and Salomons, 1981), for example, 

 while that of the Seine (Y. Monbet, personal communication) also 

 increased four-fold to ~400 yg-at N£ from 1965 to 1975. The mean 

 winter nitrate content of the North Sea shelf in the 1960s was also at 

 least two- to four-fold higher off the Thames estuary, the Wash and the 

 Rhine estuary than at the edge of the shelf (Johnston, 1973); the winter 

 phosphate content off the Dutch coast has since doubled from 1961 to 

 1978 (Van Bennekom and Salomons, 1981). Indeed, as much as 350 yg-at 

 N0.2." , ~ 10-fold the concentration of NO., in deep slope water, is now 

 found both in the Scheldt estuary and 10 km off the Belgian coast 



(Mommaerts et al., 1979). The annual production of the nearshore zone 



-2 -1 

 of the Waddensea has apparently increased from 80 to 240 g C m yr 



over 20 years (Postma, 1978) as a result of these nutrient inputs. 



With respect to global impact of the changing nutrient input from these 

 two boundaries of the shelf (land, shelf-break) and subsequent carbon 

 fixation, the MAREX program would thus address the following questions: 



a. What is the relationship between estuarine outwelling and 

 shelfbreak upwelling on the development, distribution and 

 magnitude of the spring bloom of phytoplankton, both off an 

 individual estuary and along an entire coastline? 



b. How far seaward and over what area does estuarine influence and 

 contained pollutants extend? Are phytoplankton transported 

 ungrazed across an entire shelf to the slope boundary? 



c. Can the land source of nutrients be distinguished from one 

 estuary to the next with regard to degree of eutrophication of 

 the estuary and consequent impacts on fishery resources in the 

 estuary and on/over the adjacent shelf? (For example, as a 

 result of flow and estuarine area, the Hudson estuary should 



3-3 



