STUDY NUMBER ; 10.2 (COMPLETED) 



ORGANIZATION ; University of Montana (UM) - Department of Geology 



TITLE OF STUDY ; Determination of Heavy Metal Contamination in 

 Reservoir Sediment Along the Clark Fork River, Missoula to Heron, 

 Montana 



CONTACT ( S ) ; Johnnie Moore - Department of Geology - University 



of Montana - 243-2341 



Carolyn Johns - Department of Geology - University 

 of Montana - 243-2341 



OBJECTIVE ; Determine the concentration of heavy metals-arsenic, 

 copper, cadmium, iron, lead, manganese and zinc--in the lower 

 river reservoir sediments and compare these to values found in 

 Milltown Reservoir. 



DURATION ; 1984 - 1986 



CURRENT STATUS ; During the summer of 1984, grab samples of res- 

 ervoir sediments were collected from Milltown (27 samples), Thomp- 

 son Falls (7 samples), Noxon Rapids (14 samples) and Cabinet 

 Gorge (7 samples). Additionally, core samples, averaging 25 

 cm in length were collected at Thompson Falls (3 cores) and Noxon 

 Rapids (5 cores). Six cores, approximately 150 cm in length, 

 were collected at Milltown. Two heavy metal extraction techniques 

 were utilized: acetic acid (25% v/v) and total, which involves 

 a four-hour digestion in hot aqua regia. 



Preliminary results from the acetic acid extractions 

 indicate that copper and zinc sediments concentrations in the 

 lower river reservoirs are about ten times lower than those found 

 in the Clark Fork arm at Milltown. However, sediment concentra- 

 tions of copper and zinc are still elevated over background lev- 

 els--four to eight times higher than the control stations in 

 the Blackfoot arm of the Milltown Reservoir. Arsenic concen- 

 trations from the acetic acid extractions do not appear to be 

 significantly elevated in sediments of the lower river reser- 

 voirs. 



PUBLICATIONS AND REPORTS 



Copper, Zinc and Arsenic in Bottom Sediments of Clark Fork River 

 Reservoirs--Preliminary Findings. Pages 74-88 In C.E. Carlson 

 and L. L. Bahls, (eds.). Proceedings of the Clark Fork Symposium, 

 April 19, 1985. Montana College of Mineral Science and Tech- 

 nology, Butte, Montana. 



Johns, Carolyn and Johnnie Moore, (not dated) Metals in Bottom 

 Sediments of Lower Clark Fork River Reservoirs Final Report Sub- 



51 



