Laserfiche WebLink
<br />. <br /> <br />..... <br />. . <br /> <br />. <br /> <br />1790 <br /> <br />Cadmium <br /> <br />The spatial and temporal variability of cadmium concentrations was a function of distance from the Lead- <br /> <br />ville area, dilution by tributaries, the degree ofpanitioning between the dissolved and particulate phases, and dep- <br /> <br />osition and resuspension of fluvial sediment. The median dissolved-cadmium concentration was typically largest <br /> <br />at Malta (1.2 ~gil.) and decreased substantially downstream (fig. 6). Moore and Ramamoorthy (1984) reported that <br /> <br />dissolved-cadmium concentrations in unpolluted freshwaters typically range from 10-100 ngil.. The substantial <br /> <br />decrease in dissolved-cadmium concentrations between Malta and Granite was largely due to dilution by Lake <br /> <br />Creek and increased partitioning to the particulate phase. The median percentage of cadmium in the dissolved <br /> <br />phase decreased from 60 percent at Malta to 28 percent at Granite (fig. 7). Dissolved-cadmium concentrations and <br /> <br />the median percentage of cadmium in the dissolved phase increased at Buena Vista. The increase in concentrations <br /> <br />and in percent dissolved may bave been caused by unsampled, nonpoint-sources or by the decrease in pH at Buena <br /> <br />Vista (fig. 4). Temporally, dissolved cadmium was typically largest during pre-sno'wmelt runoff (fig. 6). The <br /> <br />median total-recoverable cadmium concentration generally increased substantially between Leadville and Malta. <br /> <br />due to mine drainage, and decreased downstream from Malta,. except during snowmelt runoff (fig. 6). During <br /> <br />snowmelt runoff and pre-snowmelt runoff, the median total-recoverable cadmium concentrations were equal <br /> <br />between Leadville and Buena Vista, but they increased considerably downstream from Buena Vista during snow- <br /> <br />melt runoff (fig. 6). The downstream increase during snowmelt runoff was probably caused by the resuspension of <br /> <br />trace-element laden sediment by the elevated streamflow. <br /> <br />"'Ill"!! D'l'" H<J.':".~ <br />.".:., -;!'lIll 'i\~~- :j:;; ~,. ,?I ....'1.1/' d:: <br />. ;:~~~...~~la;.i3n1.:.. . QC.N:I ~ <br />" ...'~- <br />Subject to Revision.. (;_: <br />DO NOT QUOTE OR RE!..t:A~". <br />;-\~!,jding Approval by DireC10r, <br />U.S. Geological Survey <br /> <br />20 <br />