Open-File Report 2006–1350

U.S. GEOLOGICAL SURVEY
Open-File Report 2006–1350

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Concentrations of Elements in Sediment and Water

Samples were collected from 8 sites in Lake Roosevelt and analyzed for elemental concentrations in 28 samples of sediments, 32 samples of extracts from sequential selective extractions, and for samples of site water from 10 reservoir water samples, 32 porewater samples, 55 samples of reservoir water overlying incubation cores, and leachates from 24 higher energy tumbling experiments. Results for sediment and water samples are presented and discussed in four categories: (1) alkali and alkaline earth elements, (2) non-metals, (3) metals, and (4) lanthanide and actinide elements.

Sediment Samples

Total Digestion of Samples

Of the 36 elements analyzed following total digestion of a composite sample, 35 elements were detected in all 28 sediment samples, resulting in the detection of elements in 98 percent of the 1,008 samples (table 10; at back of report). The concentrations of alkali and alkaline earth elements varied considerably among sites (table 11; at back of report), but the variation within sites was usually small. Relative percent differences between the concentrations of sediments in the composite and concentrations of sediments in the sections and concentrations of sediments left over from spent porewater samples generally were less than 10 percent, although greater differences were found in at least one sample for all elements except rubidium (table 12; at back of report). Except for silver, concentrations greater than the reporting limit in all 28 samples were measured for all metals analyzed (tables 10 and 13; at back of report). The variations of the concentrations of metals from samples within sites were greater than those of the alkali and alkaline earth elements (table 14; at back of report). The concentrations of four lanthanide and actinide elements seemed to vary less than other elements both between sites (table 15; at back of report) and within sites (table 16; at back of report).

Sequential Selective Extraction

A dried aliquot from the composite sample from each site was sequentially and selectively extracted to estimate associations with sediment mineral phases. The percentage of concentrations of alkali and alkaline earth elements that were greater than the reporting limit were 86, 93, 98, and 99 percent for the first, second, and third extraction fractions, and the residual sediment, respectively (table 10). Concentrations of all alkali and alkaline earth elements analyzed in the four extraction fractions were greater than the reporting limit, except for cesium, lithium, potassium, and sodium. Cesium was detected in only 3 of 8 extracts from the first sequential selective extraction fraction; lithium was detected in 5 of 8 extracts from the first fraction; potassium was detected in 7 of 8 extracts from the residual fraction; and sodium was detected in 5 extracts from the first fraction, 2 of the 8 extracts from the second fraction, and 6 of 8 extracts from the third fraction (tables 10 and 17; at back of report). Selenium was detected in 6 of the 8 extracts of the two non-metals analyzed in the third fraction. In contrast, arsenic was detected in all extracts from the second fraction and in all residual sediments. The percentage of concentrations of non-metals that were greater than the reporting limit were 44, 56, 56, and 56 percent for the first, second, and third extraction fractions, and the residual sediment, respectively (table 10). Aluminum, cadmium, cobalt, copper, iron, lead, manganese, vanadium, and zinc were the metals detected in the extracts and residual sediment from all sites (table 18; at back of report). In contrast, silver was not detected in the extracts from the first three extract fractions and was detected only in the residual sediment from three sites. Bismuth was not detected in any extract from fractions 1 and 3, but was detected in 5 of 8 extracts from fractions 2 and in the residual sediment from all 8 sites. The percentage of concentrations of metals that were greater than the reporting limit were 65, 73, 69, and 84 percent for the first, second, and third extraction fractions and the residual sediment, respectively (table 10). Uranium was the only actinide element analyzed and was detected in all fraction extracts and residual sediment samples.

Water Samples

Analysis of 121 samples of reservoir water, porewater, reservoir water overlying incubation cores, and supernatants from the higher energy tumbling experiments resulted in 6,776 elemental analyses (table 10). Overall, the concentrations of only 37 percent of the analyses of water samples were greater than the reporting limit. Seventy-seven percent of the analyses of alkali and alkaline earth determinations were greater than the reporting limit. Barium, calcium, magnesium, potassium, sodium, rubidium, and strontium were detected in all 121 samples, whereas beryllium was detected in only one porewater sample. The overall percentage of detected non-metals was 51 percent, and the percentage of detections ranged from 0 for selenium to 100 percent for silica. The overall percentage of metals detected in water samples was 33 percent. Aluminum and copper were the most frequently detected metals in water samples, with detections in 107 of the 121 samples. In contrast, bismuth, chromium, niobium, silver, and zirconium were not detected in any water sample. Only 14 percent of the analyses of lanthanide and actinide elements were greater than the reporting limit. Cerium and uranium were the most frequently detected lanthanide and actinide elements, and five of the lanthanide and actinide elements (holmium, lutetium, terbium, thorium, and thulium) were not detected in any water samples. Only 23 percent of the analyses of reservoir water, which had little contact with the sediments, were detected. The percentage of porewater concentrations that were greater than the reporting limit (47 percent) was only slightly less than that of the higher energy tumbling experiment (48 percent). The percentage of analyses of reservoir water overlying the incubation cores with concentrations greater than the reporting limit (29 percent) was intermediate between the reservoir water and the leachate from the higher energy tumbling experiments.

Reservoir Water

The source of the samples of site water and the water column properties are described in table 19 (at back of report). Of the 10 samples of reservoir water analyzed, beryllium and cesium were not detected in any samples and lithium was detected in only one sample (tables 10 and 20, at back of report). Of the five non-metals analyzed, only selenium was not detected in any reservoir water sample. Concentrations of 9 of the 25 metals analyzed (aluminum, antimony, cadmium, cobalt, copper, manganese, lead, nickel, and zinc) were greater than the reporting limit (table 21, at back of report). Concentrations of lead and zinc in reservoir water from a sealed box core were higher than those collected from the surface of the water column or those from a draining box core. It is not known if these elevated concentrations for reservoir water are due to proximity to the sediments or contamination from the box corer. Only 2 of the lanthanide and actinide elements (erbium and uranium) were detected in reservoir water (table 22, at back of report). Twenty-three percent of all elements analyzed in reservoir water were detected. Within the group of elements, 71 percent of the alkali and alkaline earth element analyses, 38 percent of the non-metal analyses, 15 percent of the metal analyses, and 1 percent of the lanthanide and actinide element analyses were detected, respectively (table  10).

Porewaters

Thirty-two samples from eight sites were analyzed either as single porewater samples from an individual core or as composite porewater samples from multiple cores (table 19). Seven of the 10 alkali and alkaline earth elements and one (silica) of the five non-metals were detected in all 32 porewater samples (tables 10 and 23, at back of report). Selenium was the only non-metal element not detected in any samples of porewater. Concentrations of only one analysis of beryllium and seven analyses of lithium were greater than the reporting limit. Bismuth, chromium, niobium, silver, thallium, and zirconium were not detected in any porewater samples (table 24; at back of report). Only aluminum and lead were detected in all 32 porewater samples. Cerium and neodymium were the most frequently detected lanthanide elements in porewater samples (table 25; at back of report). Within the group of elements analyzed in 32 porewater samples, 81 percent of the alkali and alkaline earth element analyses, 54 percent of the non-metal analyses, 42 percent of the metal analyses, and 29 percent of lanthanide and actinide element analyses were greater than the reporting limit, respectively (table 10).

Water Overlying Incubation Cores

Eight cores between 3 cm long (LR-7) and 12.3 cm long (LR-4A) were incubated with between 142 and 382 mL of reservoir water overlying the sediment (table 26, at back of report). Concentrations of elements from 55 incubation samples collected from reservoir water overlying the eight cores between September 22 and November 3, 2004, are listed in tables 27, 28, and 29 (at back of report). Concentrations of seven of the 10 alkali and alkaline earth elements were detected in all 55 samples (tables 10 and 27). No incubation sample had concentrations of beryllium greater than the reporting limit, and only one sample had concentrations of lithium greater than the reporting limit. For the non-metals, silica and sulfate were detected in all incubation samples, but selenium was not detected in any incubation samples (table  27). Bismuth, chromium, niobium, silver, tantalum, titanium, thallium, vanadium, and zirconium were not detected in water from any incubation sample (table  28). In contrast, copper was detected in all 55 incubation samples (table  28). Only five (cerium, europium, gadolinium, uranium and ytterbium) of the 16 lanthanide and actinide elements were detected in one or more incubation samples. Uranium was detected in 24 of the 55 incubation samples (table 29). Within the group of elements analyzed in the 55 incubation samples, 74 percent of the alkali and alkaline earth element analyses, 49 percent of the non-metal analyses, 24 percent of the metal analyses, and 4 percent of rare earth element analyses were detected, respectively.

Supernatants from Higher Energy Tumbling Experiment

The top sediment from eight incubation cores, the bottom sediment from two cores, and two samples of river sediment with slag were tumbled for 43 days. Weights of dry sediment, of porewater contained in the original sample, and of site water added to the bottles during the tumbling experiment are given in table 30 (at back of report). Seven of the 10 alkali and alkaline earth elements were detected in all 24 samples from the tumbling experiment (tables 10 and 31, at back of report). Beryllium was not detected in any samples from the tumbling experiment, and concentrations of lithium in only 10 samples were greater than the reporting limit. For the non-metals, concentrations for all analyses of silica, 21 analyses of arsenic, and 13 of the analyses of sulfate were greater than the reporting limit in 24 tumbling experiment samples. Bismuth, chromium, niobium, silver, tantalum, and zirconium elements were not detected in any of the tumbling samples (table 32, at back of report). Aluminum, manganese and zinc were detected in all 24 samples from the tumbling experiment. Six of the 16 lanthanide and actinide elements were not detected in any tumbling experiment samples (table  33, at back of report). In contrast, cerium was detected in 22 of 24 samples from the tumbling experiment. Within the group of elements analyzed in 24 samples from the tumbling experiments, 81 percent of the alkali and alkaline earth element analyses, 56 percent of the non-metal analyses, 48 percent of the metal analyses, and 22 percent of the lanthanide and actinide element analyses were detected, respectively.

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