240 WOODWELL, RICH, AND HALL 



DISCUSSION BY ATTENDEES 



Riley: Does groundwater seepage contribute a significant amount of 

 dissolved organic carbon (DOC) to Flax Pond? 



Woodwell: I do not know. Some of the groundwater of Long Island 

 certainly contains organic compounds. I do not know whether significant 

 horizontal movement of these compounds occurs. 



Likens: DOC averages about 1 mg/liter in groundwater at the Hubbard 

 Brook Experimental Forest in New Hampshire. 



Woodwell: Dr. Wetzel points out that in a lake in which he and his 

 colleagues have worked, about one-third of the DOC comes in as dissolved 

 carbon in groundwater. 



Dr. Charles Hall points out that in Flax Pond, the estuary that I spoke of, 

 the groundwater probably does not carry a large fraction of the DOC into the 

 pond because the flux of water and DOC through tidal exchanges with Long 

 Island Sound is very large. 



Dr. Allen asks if we have any measurements of atmospheric exchanges of 

 carbon in Flax Pond. The answer is that we do not; we plan to do an intensive 

 study of just those exchanges a year from now. 



Olson: How are we supposed to compare length of coastline with areas of 

 estuary in Fig. 1? 



Woodwell: The National Estuarine Pollution Study includes a tabulation of 

 the area of estuary for diverse sections of coastline of the United States, 

 including Alaska and Hawaii, and provides those ratios. The ratios are in the 

 range of about 0.03 to about 9 sq miles of estuary including marsh per mile of 

 coast. We applied the average for all coastlines to the temperate- and 

 tropical-zone coastlines of the world. We measured the coastline lengths 

 ourselves on maps of uniform scale. We considered large estuaries separately — 

 river mouths, Chesapeake Bay, the Baltic Sea. This is a very crude way of 

 obtaining the data, but there appears to be no other tabulation. 



