STUDY NUMBER ; 9.1 ( COMPLETED ) 



ORGANIZATION ; U.S. Geological Survey (USGS) 



TITLE OF STUDY ; Analysis of Clark Fork River Bottom Sediment 

 and Biota for Trace Metal Content 



CONTACT ( S ) ; US Geological Survey Research Staff in Denver, 



Colorado 



Ned Andrews - US Geological Survey, Denver - (303) 

 236-5004 



Sam Luoma - US Geological Survey, Menlo Park, 

 California - (415) 323-8111 



OBJECTIVE ; Determine the longitudinal distribution of trace 

 metals in the sediment and macroinvertebrates of the Clark Fork 

 River; develop field methods for collecting representative sed- 

 iment samples and methods for processing samples which will ensure 

 their chemical stability; investigate the relationship of fluvial 

 mechanics to metal concentrations in the river. 



DURATION : 1984 



CURRENT STATUS ; During 1984, bottom sediment samples were col- 

 lected from 44 sites at 3 to 5 mile intervals between Warm Springs 

 and St. Regis. Benthic macroinvertebrates were also collect- 

 ed at fifteen of these sites. During the normal runoff period 

 of 1985, depth and width integrated samples were collected once 

 every three days from three sites on the Clark Fork River (near 

 Deer Lodge, Gold Creek and Missoula) as well as from major tri- 

 butary streams. These large volume samples (30 to 40 liters) 

 were centrifuged and preserved in the field. Particle size dis- 

 tribution and heavy metal analyses (for lead, zinc, copper, cad- 

 mium and arsenic) were performed on all sediment and water column 

 samples. The benthic macroinvertebrates were analyzed for their 

 heavy metal content. 



PUBLICATIONS AND REPORTS 



Data summary for 1985 sampling. 



415 



