2,000 



MAY 

 1965 



JULY 



JULY 



Figure 3. — A comparison of the behavior of the model (smoothly curved lines) with the values used to construct the 



model (irregular lines). 



BIOGEOCHEMISTRY PROGRAM 



Douglas A. Wolfe, Chief 



The rapid accumulation of certain radio- 

 nuclides by estuarine organisms may reflect 

 the metabolism of trace elements or the 

 physical adsorption of ions on biological sur- 

 faces. Complete understanding of the cycling 

 of radionuclides in the estuary involves knowl- 

 edge of the geochemical characteristics of the 

 estuary, of the elemental composition of estua- 

 rine organisms, of transport mechanisms 

 operating in the organisms incorporating the 

 elements, and of the physiological disposition 

 (metabolism) of the elements. The Biogeo- 

 chemistry Program is gathering data on vari- 

 ous aspects of these broad research areas. 

 During fiscal year 1968, we have worked 

 principally on the estuarine biogeochemistry 

 of cesium 137 from nuclear fallout. The ele- 

 mental exchange of zinc between estuarine 

 water and sediments was studied in conjunction 

 with the Pollution Studies Program (see that 



section of the report for a description of the 

 research). Other research projects have in- 

 cluded: a study on the interference from cal- 

 cium in atomic absorption spectrophotometry, 

 and the estimation of the growth rate of the 

 estuarine clam Rangia cuneata . Discussions 

 of these projects follow. 



ESTUARINE BIOGEOCHEMISTRY OF 

 CESIUM 137 



Douglas A. Wolfe, Jo-Ann Lewis, and 

 Jeraldine H. Brooks 



Cesium 137 is one of the most important 

 constituents of the nuclear fission products 

 from the standpoint of environmental health. 

 Over 6 percent of long-lived fission yield from 

 uranium or plutonium is cesium 137, an 



13 



