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Chemical and colloidal analyses of natural seep water collected from the exploratory studies facility inside Yucca Mountain,Nevada, USA 总被引:1,自引:0,他引:1
Cizdziel JV Guo C Steinberg SM Yu Z Johannesson KH 《Environmental geochemistry and health》2008,30(1):31-44
Yucca Mountain is being considered as a geological repository for the USA’s spent nuclear fuel and high-level nuclear waste.
Numerous groundwater seeps appeared during March 2005 within the exploratory studies facility (ESF), a tunnel excavated in
the mountain. Because of the relevance to radionuclide transport and unsaturated zone-modeling studies, we analyzed the seep
samples for major anions and cations, rare earth elements, and colloids. Major ion species and elemental concentrations in
seep samples reflect interaction of the water with the volcanic rock and secondary calcites. Elemental fractograms from flow-injection
field-flow fractionation ICP–MS scans detected Br, Ca, Cl, Cu, Fe, I, Mg, Si, Sr, W, and U at void fractions, suggesting they
may be present in the form of dissolved anions. Colloids approximately 10 nm in hydrodynamic diameter, possibly calcite, were
also present in the seepage samples. Geochemical calculations indicate, however, these may be an artifact (not present in
the groundwater) which arose because of loss of CO2 during sample collection and storage. 相似文献
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Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate bound mercury (PBM) were measured on the University of Mississippi campus from July 2011 to June 2012. It is believed to be the first time that concentrations of atmospheric mercury species have been documented in northern Mississippi, and at a location with relatively large and sudden swings in population. The mean concentration (±1SD) of GEM was 1.54 ± 0.32 ng m−3; levels were lower and generally more stable during the winter (1.48 ± 0.22) and spring (1.46 ± 0.27) compared with the summer (1.56 ± 0.32) and fall (1.63 ± 0.42). Mean concentrations for GOM and PBM were 3.87 pg m−3 and 4.58 pg m−3, respectively; levels tended to be highest in the afternoon and lowest in the early morning hours. During the fall and spring academic semesters concentrations and variability of GOM and PBM both increased, possibly from vehicle exhaust. There were moderate negative correlations with wind speed (all species) and humidity (GOM and PBM). Backward air mass trajectory modeling for the ten highest peaks for each mercury species revealed that the majority of these events occurred from air masses that passed through the northern continental US region. Overall, this study illustrates the complexity of temporal fluctuations of airborne mercury species, even in a small town environment. 相似文献
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The Las VegasWash, which drains the Las Vegas valley watershed and provides the second largest inflow to Lake Mead, is being dramatically altered with erosion control structures and wetland restoration efforts. The impact of these changes on the cycling and distribution of Hg and Se is of particular interest because of their tendency to bioaccumulate and because of a lack of information on these contaminants in the Wash. In this study, we determined concentrations of Hg and Se in surface water (monthly), groundwater (once) and sediments (quarterly) from strategic locations within and along theWash during 2002 and 2003. The data was used to characterize Se sources and loading into theWash. Samples containing resurfacing groundwater and urban runoff (LW10.75 and Duck Creek) had significantly higher yearly means (13.7 ± 4.4 and 23.8 ± 4.1μg/L, respectively) compared with mainstream samples containing primarily treated wastewater (2.8 ± 0.8μg/L). Investigation of Se in tributaries, street runoff and rain suggest that the source of the elevated Se is likely groundwater seeps located within a relatively narrow geographic band on the southeast side of the valley. Se content of sediments was similar, except for LW10.75 which was rich in organic matter. Hg concentrations in the water and sediments were low, averaging 4±5 ng/L and 34±20 ng/g, dw, respectively. Overall, this study suggests that water quality remains relatively stable despite changes in theWash and managers of developing wetlands should not use tributary water as source water. 相似文献
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There is concern that elevated levels of selenium found in the source water of a newly formed wetland park in Las Vegas, Nevada,
may have detrimental effects on local wildlife. In this study, we collected and analyzed water samples monthly for a three
year period from the inflow and outflow of the system. We also gathered dominant aquatic plants and selected terrestrial plants
and analyzed the water and plant tissues (root, shoot, leaf and flower) for selenium by high resolution Inductively Coupled
Plasma Mass Spectrometer. Except for storm events and the introduction of an alternative low selenium content source water
during summer low-flow conditions, selenium in the water was relatively stable. The concentration in the outflow tended to
be slightly lower than the inflow. Concentrations of selenium in the dominant plant taxa in this wetlands were typical of
ecosystems in the western United States and varied by taxa, tissue type, localized conditions (e.g., contact with selenium-laden
water), and to a lesser extent, seasons. Selenium in the aquatic plant spiny naiad (Najas marina) was relatively high and may pose an ecological risk to wildlife during the late spring and summer. Additional work is underway
investigating aquatic food chain accumulations of selenium as well as mass balance of selenium in the system. 相似文献
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Total mercury (Hg) concentrations were determined in seven tissues (skeletal muscle, liver, blood, gonad, brain, gill, and heart) of 59 striped bass and four tissues (muscle, liver, blood, and gonad) of 69 largemouth bass, 76 channel catfish, 12 bluegill, and 22 blue tilapia collected from Lake Mead, USA. Mercury levels generally increased according to trophic level and fish length. For striped bass, mean Hg levels (ng g(-1), wet mass) were highest in the liver (531), followed by muscle (309), heart (186), gonad (136), brain (77), gill (52), and blood (36). Similarly, Hg levels in the catfish and tilapia were liver > muscle > gonad > blood. In contrast, largemouth bass and bluegill had the highest levels in muscle, followed by liver, gonad, and blood. Generally, Hg levels were strongly correlated among the tissues, especially for blood/muscle and blood/liver. As the body burden of Hg increased, the concentration in blood and organs increased relative to the concentration in muscle. The trend was most pronounced for the liver. These relationships could form the basis of a predictive model and suggest that blood and muscle (plugs) could be useful for a non-lethal measure of Hg concentration and exposure in fish. For the striped bass, elevated Hg levels in the tissues were also correlated with degree of emaciation. Liver-to-muscle ratios were similar to literature values, except for tilapia with an average ratio of approximately 1.7, which is higher than generally reported for non-piscivores. Finally, this study demonstrates the usefulness of a solid sampling approach in trace element monitoring, especially as pertaining to in vivo analysis, analysis of a large number of samples and reduction of contamination risk. 相似文献
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Turner M Rudin M Cizdziel J Hodge V 《Environmental pollution (Barking, Essex : 1987)》2003,125(2):193-203
Two soil profiles were collected from undisturbed areas near the Nevada Test Site (NTS). The activity of 137Cs in the surface layer of the downwind Queen City Summit profile is three times higher than at the upwind site at Searchlight, NV (41.1+/-0.6 mBq/g vs. 13.0+/-0.4 mBq/g), and the 239,240Pu activity is 100 times greater (51+/-2 mBq/g vs. 0.52+/-0.03 mBq/g). An examination of the literature suggests that the 137Cs/239,240Pu and the 239,240Pu/238Pu activity ratios in soils and sediments from the northern hemisphere, due to fallout from atmospheric atomic weapons testing, have generalized values of 36+/-4 and 30+/-4, respectively (as of 1 July 1995). Deviations from these values may indicate possible contamination by sources other than fallout. Data from the surface soil of the downwind Queen City Summit profile yield a 137Cs/239,240Pu ratio of 0.81+/-0.02 and a 239,240Pu/238Pu ratio of 78+/-6. Clearly, an increase in 239,240Pu relative to 137Cs or 238Pu can account for these observations. There is compelling evidence that this "excess" 239,240Pu came from activities at the NTS during the aboveground testing of nuclear devices, more than likely from safety tests, some 40 years ago, and/or during the interim by the wind-driven resuspension of contaminated surface soil on the NTS and its transport off-site. Moreover, the two concentration profiles show that high percentages of both of these elements are retained for decades in the upper few centimeters of soil in Nevada's desert environment. 相似文献
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