FLOOD10381 - Laserfiche WebLink

Home Browse Search

The annual means for dissolved and suspended potas- sium were very similar. No prescribed water use criteria could be found specifically for potassium; no signifi- cant accumulation of potassium in the pool sediments could be'inferred from the data in table 4. Lithium. - Lithium is potentially toxic to plants [17]. For this reason a limit of 2.5 mg/I was suggested by the U,S, Federal Water Pollution Control Administration (now the Environmental Protection Agency) in 1968. Durum and Haffty [8] show a median concentration of dissolved lithium of 0.0011 mg/I in the rivers of North America, while Durfor and Becker [7] reported 0.002 mg/I lithium, The mean value for lithium in the Arkansas River and Pueblo Reservoir was consistently higher than these values, averaging 0.017 :t 0,004 mg/I and 0.014 :t 0,004 mg/I in the pool for the two sam- pling years of the project, and 0.015 :t 0.007 mg/I and 0.013 :t 0.008 mg/I at the inlet. The lithium in the sus- pended fraction was nearly negligible at 0.0007 :t 0.003 mg/I and 0,0006 :t 0,002 mg/I, respectively, for the pool. The trends observed for lithium follow the trend observed for sodium very closely (figs. 12 and 20), The surface trend for lithium follows the sodium curve (fig. 20) very closely, although the concentration of lithium is about 1000 times less. In April 1975, a decreasing surface trend was observed for sodium and lithium, with sodium concentrations almost exactly 1000 times greater than lithium at all sampling sites, Seasonal trends and depth profiles for lithium also parallel so- dium quite closely, Copper. - It has been suggested by Garrels and Christ [18] that cupric oxide or hydroxy-carbonate minerals would tend to limit the solubility of copper in aerated water to about 0,064 mg/I at a pH of 7.0, decreasing to 0,006 mg/I at a pH of 8.0, Hem [3] notes, however, that higher values have been observed, Dissolved copper levels for Pueblo Reservoir averaged 0.004 :t 0.001 mg/I during the 1974-75 sampling year and 0.004 :t 0.002 mg/I during the 1975-76 sampling year, The highest average for the pool was 0.001 :t 0.005 mg/I (December 1975), and the lowest averaged less than detectable limits on three separate sampling dates. The dissolved levels observed are completely consistent with predic- tions of Garrels and Christ [18], considering the pre- valent pH's of about eight, Hem [3] also notes that copper is essential to the nutrition of plants and ani- mals. However, no mechanism for copper removal be- sides inorganic precipitation is necessary to explain the observed levels. The suspended levels of copper were comparable to the dissolved levels. The reservoir pool average for the 1974- 75 sampling year was 0.004 :t 0.001 mg/I and 0.006 :t 0.003 mg/lduring the 1974-7 sampling year. The high- est pool average for a single month was 0.015 :t 0,007 mg/I (December 1975). N ndetectable low averages were recorded for five mont Iy sampling periods. A seasonal trend with a ma imum value occurring dur- ing the early winter months as observed for dissolved copper. Comparison of the pool trend to the river at the inlet and outlet reveals similar trend. Figure 24 drawn from the pre-impoun menfdata in appendix C also indicates a seasonal tre d. The average dissolved copper level at the two sites monitored during the pre- impoundment study was 0008 :t 0.005 mg/I (some- what higher than the avera e for the reservoir poon, while the average copper val es obtained at the inlet of the reservoir were consisten with the reservoir pool, 0,004 :t 0.003 mg/I and 0, 04:t 0.005 mg/I for each year, respectively. No defin te surface or spatial trend was observed for copper. Kopp and Kroner [9] dete ed copper in 74 percent of the dissolved samples and 2 percent of the suspended samples collected from the s rface waters of the United States, Means of 0,015 mg/ (dissolved) and 0.26 mg/I (suspended) were recorded rom the samples in which copper was detected. Copper in the sediments av raged 31 :t 17 mg/I in the pre-impoundment flood pi in and only slightly higher at 37:t 13 mg/I in the sampl s collected in the reservoir. At site F near the inlet, ho ever, sedJments yielded 59 mg/I copper, indicating so e copper loading into the sediments may be occurring near the inlet, Zinc. - Solubility controls do not tend to limit the concentrations of zinc obs ved in natural water, but rather the availability of zin from rock and soil [3] or from pollution sources. A s' nificant source of zinc in the Arkansas River is from the mine drainages in the Leadville area, particularl California Gulch [19], Durum, et al. [10] reported zinc in a range of 0,010 to 0.050 mg/I in most samples obtained from surface wa- ters, but occasionally valu s exceeding 5.0 mg/I, the recommended upper ,limit f r drinking water, were ob- served. In this study a mean f 0.010:t 0.015 mg/I zinc was observed the first sa pling year (1974-75) and 0,007 :t 0.002 mg/I during he second (1975-76). The low average occurred in Ma ch 1975, at 0.001 :t 0,002 mg/1. The high average was ,038:t 0.122 mg/I in April 1975. That average include several extreme values cb- tained from samples taken t the bottom of the reser- voir, including a value of O. 68 mg/I obtained at site A bottom at a depth of 15 me res, 26