STUDY NUMBER ; 9.1 



ORGANIZATION ; U.S. Geological Survey (USGS) 



TITLE OF STUDY ; Analysis of Clark Fork River Bottom Sediment 

 and Biota for Trace Metal Content 



CONTACTS ; USGS Research Staff in Denver, Colorado 



Ned Andrews - USGS, Denver - (303) 236-5004 



Sam Luoma - USGS, 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 representa- 

 tive sediment 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 

 collected from 44 sites at 3 to 5 mile intervals between Warm 

 Springs and St. Regis. Benthic macroinvertebrates were also 

 collected 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 tributary streams. These large volume 

 samples (30 to 40 liters) were centrifuged and preserved in 

 the field. Particle size distribution and heavy metal 

 analyses (for lead, zinc, copper, cadmiun and arsenic) have 



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