Mercury and Other Mining-Related Contaminants in Ospreys Along the Upper Clark Fork River, Montana, USA
ABSTRACT We investigated links between mining-related contaminants in river sediment and their occurrence in nestling ospreys (Pandion haliaetus) in the Clark Fork River Basin, Montana, USA. Blood and feather samples from 111 osprey chicks were collected during 4 years from nests along river sections with greatly different sediment concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), and mercury (Hg). No significant differences between river sections were found among Zn (3,150 ± 160 μg L(-1)) and Cd (<5 μg L(-1)) concentrations in blood. Cu, Pb, and As concentrations in blood were significantly increased in chicks from the most contaminated river sections (mean values of 298, 8.9, and 100 μg L(-1), respectively). Cu, Zn, and Pb concentrations increased significantly during a year of above-average river runoff combined with high suspended sediment loads in rivers. Total Hg concentrations in blood and feathers were highly correlated and depended on the geographic locations of the nests. The lowest blood concentrations of Hg were observed in the most upstream river section (mean 151 μg L(-1)) where total sediment concentrations were increased (0.80 mg kg(-1)). River sections with intermediate blood concentrations (mean 206 and 303 μg L(-1)) were associated with low to intermediate sediment concentrations (0.058 and 0.46 mg kg(-1)). The highest concentrations of Hg in ospreys (mean 548 μg L(-1)) were observed downstream from a contaminated tributary (1-4 mg kg(-1) in sediment). In river sections with lower Hg concentrations in sediment, there was a negative correlation between blood Hg concentration and chick mass, presumably due to high deposition rates into growing feathers. This relationship was absent in sections of high Hg exposure. Osprey blood and feathers are suitable for monitoring Hg in aquatic ecosystems; however, responses of As, Cd, Cu, Pb, and Zn are more subtle.
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ABSTRACT: Recent research has highlighted the transfer of contaminants from aquatic to terrestrial ecosystems via predation of aquatic emergent insects by riparian consumers. The influence of adjacent land use and land cover (LULC) on aquatic-to-terrestrial contaminant transfer, however, has received limited attention. From 2010 to 2012, at 11 river reaches in the Scioto River basin (OH, USA), we investigated the relationships between LULC and selenium (Se) and mercury (Hg) concentrations in four species of riparian swallows. Hg concentrations in swallows were significantly higher at rural reaches than at urban reaches (t=-3.58, P<0.001, df=30), whereas Se concentrations were positively associated with adjacent land cover characterized by mature tree cover (R(2)=0.49, P=0.006). To an extent, these relationships appear to be mediated by swallow reliance on aquatic emergent insects. For example, tree swallows (Tachycineta bicolor) at urban reaches exhibited a higher proportion of aquatic prey in their diet, fed at a higher trophic level, and exhibited elevated Se levels. We also found that both Se and Hg concentrations in adult swallows were significantly higher than those observed in nestlings at both urban and rural reaches (Se: t=-2.83, P=0.033, df=3; Hg: t=-3.22, P=0.024, df=3). Collectively, our results indicate that riparian swallows integrate contaminant exposure in linked aquatic-terrestrial systems and that LULC may strongly regulate aquatic contaminant flux to terrestrial consumers.Science of The Total Environment 06/2013; 463-464C:42-50. DOI:10.1016/j.scitotenv.2013.05.065 · 4.10 Impact Factor
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ABSTRACT: Arsenic (As) and cadmium (Cd) pollution in water is an important global issue. Phytofiltration is an eco-friendly technology that helps clean up pollutants using ornamental plants, such as Micranthemum umbrosum (J.F. Gmel) S.F. Blake. After a seven-day hydroponic experiment, M. umbrosum removed 79.3-89.5% As and 60-73.1% Cd from 0 to 1.0 microg As mL(-1) and 0.3 to 30.0 microg Cd mL(-1) solutions, respectively. For As treatment, root to stem and stem to leaf translocation factors greater than 1.0 indicated that accumulation of As in leaves was large compared to that in stem and roots. However, the accumulation of Cd in roots was higher than that in the leaves and stem. In addition, M. umbrosum completely removed Cd within three days from 0.38 to around 0 microg mL(-1) Cd in the solution when the plant was exchanged daily. Bio-concentration factors (2350 for As and 3027 for Cd) for M. umbrosum were higher than for other As and Cd phytoremediators. The results show that M. umbrosum can be an effective accumulator of Cd and a hyper-accumulator of As, as it can lower As toxicity to a level close to the limit recommended by the World Health Organization (0.01 microg As mL(-1)).International Journal of Phytoremediation 11/2013; 15(10):1010-21. DOI:10.1080/15226514.2012.751356 · 1.74 Impact Factor
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ABSTRACT: Mercury (Hg) is a global pollutant that bioaccumulates and biomagnifies in food chains, and is associated with adverse effects in both humans and wildlife. The Hg levels detected in blood obtained from Eagle Owl (Bubo bubo) chicks in Southeast Spain (Murcia) can be considered low (mean Hg concentration in blood from 2006 to 2012 was 36.83±145.58μg/l wet weigh, n=600), and it is therefore unlikely that Hg pollution can negatively affect their breeding. Positive correlation (r=0.339, p<0.001, n=229) was found to exist between the Hg concentrations in the blood and back feathers of the chicks. We provide a regression equation that could be helpful to estimate blood Hg levels when analyzing Hg concentrations in back feathers. Blood Hg concentrations in Eagle Owls have shown positive correlations with Hg levels in rabbit muscles, more evident in nests from the Northern area (r=0.600, p=0.014, n=16), where rabbits are the main prey of Eagle Owls. The best Linear Mixed Model to explain variations in blood Hg concentrations in nestling Eagle Owls includes year and location within the mining area as variables. The variable year is assigned the largest value of relative importance, followed by the location in the ancient mining sites and then the zone. Rainfalls may have an effect on the temporal differences in the blood Hg concentrations of nestling Eagle Owls. Although the studied region is not considered Hg polluted, the Hg levels were higher in Eagle Owls and European Rabbits from areas within the ancient mining sites as compared to those in the entire region. This result shows that spatial differences in Hg concentrations in Eagle Owls may be affected by local contamination, and that the role of diet composition may be less significant.Science of The Total Environment 02/2014; 470-471C:1132-1139. DOI:10.1016/j.scitotenv.2013.10.063 · 4.10 Impact Factor