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Remediation of cadmium-contaminated soil by extraction with para-sulphonato-thiacalix[4]arene, a novel supramolecular receptor
2012
Li, Yushuang | Hu, Xiaojun | Song, Xueying | Sun, Tieheng
Batch extractions were conducted to evaluate the performance of para-sulphonato-thiacalix[4]arene (STC[4]A), a novel supramolecular receptor, for removing cadmium (Cd) from soil. The extraction mechanism was investigated by determination of the conditional stability constants (log K) of the STC[4]A-Cd complex. The influences of various variables were examined, including pH, contact time, and extractant concentration. The Cd extraction efficiency increased with increasing pH, reaching the maximum at pH 11 and then declining at higher pH values. This pH dependence was explained by the variation in the log K value of the STC[4]A-Cd complex along with pH change. When the STC[4]A dose was increased to an STC[4]A:Cd molar ratio of 2.5:1, Cd was exhaustively removed (up to 96.8%). The comparison experiment revealed that the Cd extraction performance of STC[4]A was almost equivalent to that of EDTA and significantly better than that of natural organic acids. STC[4]A extraction could efficiently prevent co-dissolution of soil minerals.
显示更多 [+] 显示较少 [-]Impacts of oil sands process water on fen plants: Implications for plant selection in required reclamation projects
2012
Pouliot, Rémy | Rochefort, Line | Graf, Martha D.
Fen plant growth in peat contaminated with groundwater discharges of oil sands process water (OSPW) was assessed in a greenhouse over two growing seasons. Three treatments (non-diluted OSPW, diluted OSPW and rainwater) were tested on five vascular plants and four mosses. All vascular plants tested can grow in salinity and naphthenic acids levels currently produced by oil sands activity in northwestern Canada. No stress sign was observed after both seasons. Because of plant characteristics, Carex species (C. atherodes and C. utriculata) and Triglochin maritima would be more useful for rapidly restoring vegetation and creating a new peat-accumulating system. Groundwater discharge of OSPW proved detrimental to mosses under dry conditions and ensuring adequate water levels would be crucial in fen creation following oil sands exploitation. Campylium stellatum would be the best choice to grow in contaminated areas and Bryum pseudotriquetrum might be interesting as it has spontaneously regenerated in all treatments.
显示更多 [+] 显示较少 [-]Toxicological significance of mercury in yellow perch in the Laurentian Great Lakes region
2012
We assessed the risks of mercury in yellow perch, a species important in the trophic transfer of methylmercury, in the Great Lakes region. Mean concentrations in whole perch from 45 (6.5%) of 691 waters equaled or exceeded 0.20 μg/g w.w., a threshold for adverse effects in fish. In whole perch within the size range eaten by common loons (<100 g), mean concentrations exceeded a dietary threshold (0.16 μg/g w.w.) for significant reproductive effects on loons in 19 (7.3%) of 260 waters. Mean concentrations in fillets of perch with length ≥ 15.0 cm, the minimum size retained by anglers, exceeded the USEPA criterion (0.3 μg/g w.w.) in 26 (6.4%) of 404 U.S. waters and exceeded the Ontario guideline (0.26 μg/g w.w.) in 35 (20%) of 179 Ontario waters. Mercury levels in yellow perch in some waters within this region pose risks to perch, to common loons, and to mercury-sensitive human populations.
显示更多 [+] 显示较少 [-]Imaging of metal bioaccumulation in Hay-scented fern (Dennstaedtia punctilobula) rhizomes growing on contaminated soils by laser ablation ICP-MS
2012
Koelmel, Jeremy | Amarasiriwardena, Dulasiri
Understanding Pb removal from the translocation stream is vital to engineering Pb hyperaccumulation in above ground organs, which would enhance the economic feasibility of Pb phytoextraction technologies. We investigated Cu, Pb, Sb and Zn distributions in Hay-scented fern (Dennstaedtia punctilobula) rhizomes on shooting range soils by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), analyzing digested rhizomes, stems, and fronds using ICP-MS. Nutrients Cu and Zn concentrated in fronds while toxic elements Pb and Sb did not, showing potential Pb and Sb sequestration in the rhizome. Frond and rhizome concentration of Pb was 0.17 ± 0.10% and 0.32 ± 0.21% of dry biomass, respectively. The ²⁰⁸Pb/¹³C and ¹²¹Sb/¹³C determined by LA-ICP-MS increased from inner sclerotic cortex to the epidermis, while Pb concentrated in the starchy cortex only in contaminated sites. These results suggest that concentration dependent bioaccumulation in the rhizome outer cortex removes Pb from the vascular transport stream.
显示更多 [+] 显示较少 [-]Enhancement of life cycle assessment (LCA) methodology to include the effect of surface albedo on climate change: Comparing black and white roofs
2012
Susca, Tiziana
Traditionally, life cycle assessment (LCA) does not estimate a key property: surface albedo. Here an enhancement of the LCA methodology has been proposed through the development and employment of a time-dependent climatological model for including the effect of surface albedo on climate. The theoretical findings derived by the time-dependent model have been applied to the case study of a black and a white roof evaluated in the time-frames of 50 and 100 years focusing on the impact on global warming potential. The comparative life cycle impact assessment of the two roofs shows that the high surface albedo plays a crucial role in offsetting radiative forcings. In the 50-year time horizon, surface albedo is responsible for a decrease in CO₂eq of 110–184 kg and 131–217 kg in 100 years. Furthermore, the white roof compared to the black roof, due to the high albedo, decreases the annual energy use of about 3.6–4.5 kWh/m².
显示更多 [+] 显示较少 [-]Toxicity assessment of simulated urban runoff containing polycyclic musks and cadmium in Carassius auratus using oxidative stress biomarkers
2012
Chen, Fang | Gao, Jie | Zhou, Qixing
The objective of this study was to assess potential toxic effects of simulated urban runoff on Carassius auratus using oxidative stress biomarkers. The activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the content of malondialdehyde (MDA) in the liver of C. auratus were analyzed after a 7-, 14- and 21-day exposure to simulated urban runoff containing galaxolide (HHCB) and cadmium (Cd). The results showed that the activity of antioxidant enzymes and the content of MDA increased significantly exposed to the simulated urban runoff containing HHCB alone or mixture of HHCB and Cd. The activity of the investigated enzymes and the content of MDA then returned to the blank level over a longer period of exposure. The oxidative stress could be obviously caused in the liver of C. auratus under the experimental conditions. This could provide useful information for toxic risk assessment of urban runoff.
显示更多 [+] 显示较少 [-]One year intensive PM₂.₅ bound polycyclic aromatic hydrocarbons monitoring in the area of Tuscany, Italy. Concentrations, source understanding and implications
2012
Martellini, Tania | Giannoni, Martina | Lepri, Luciano | Katsoyiannis, Athanasios | Cincinelli, Alessandra
Polycyclic aromatic hydrocarbons (PAHs) associated to PM₂.₅ particles were monitored at three sites in the region of Tuscany, Italy, during the period March 2009–March 2010. PAH concentrations ranged between 0.92 ng m⁻³ and 13 ng m⁻³. The spatial and seasonal differences observed at the three sites are discussed and attributed to specific PAH sources. Benzo[a]Pyrene average annual values were below the EU limit value of 1.0 ng m⁻³. The results of this study suggest that emissions from commuting and work related traffic play an important role for the city of Florence, whereas for the city of Livorno, the harbor activities seem to impact the PAH burden substantially, as well. The PAH cancer risk (expressed as the “BaPE index”) has shown a 6-fold decline compared to early 1990's concentrations and 2- to 3-fold decline compared to the late 1990's.
显示更多 [+] 显示较少 [-]A sensitive crude oil bioassay indicates that oil spills potentially induce a change of major nitrifying prokaryotes from the Archaea to the Bacteria
2012
Urakawa, Hidetoshi | Garcia, Juan C. | Barreto, Patricia D. | Molina, Gabriela A. | Barreto, Jose C.
The sensitivity of nitrifiers to crude oil released by the BP Deepwater Horizon oil spill in Gulf of Mexico was examined using characterized ammonia-oxidizing bacteria and archaea to develop a bioassay and to gain further insight into the ecological response of these two groups of microorganisms to marine oil spills. Inhibition of nitrite production was observed among all the tested ammonia-oxidizing organisms at 100ppb crude oil. Nitrosopumilus maritimus, a cultured representative of the abundant Marine Group I Archaea, showed 20% inhibition at 1 ppb, a much greater degree of sensitivity to petroleum than the tested ammonia-oxidizing and heterotrophic bacteria. The differing susceptibility may have ecological significance since a shift to bacterial dominance in response to an oil spill could potentially persist and alter trophic interactions influenced by availability of different nitrogen species.
显示更多 [+] 显示较少 [-]Fate of triclosan in field soils receiving sewage sludge
2012
Butler, E. | Whelan, M.J. | Sakrabani, R. | van Egmond, R.
The anti-microbial substance triclosan can partition to sewage sludge during wastewater treatment and subsequently transfer to soil when applied to land. Here, we describe the fate of triclosan in a one-year plot experiment on three different soils receiving sludge. Triclosan and methyl-triclosan concentrations were measured in soil samples collected monthly from three depths. A large fraction of triclosan loss appeared to be explained by transformation to methyl-triclosan. After 12 months less than 20% of the initial triclosan was recovered from each soil. However, the majority was recovered as methyl-triclosan. Most of the chemical recovered at the end of the experiment (both triclosan and methyl-triclosan) was still in the top 10 cm layer, although there was translocation to lower soil horizons in all three soils. Between 16.5 and 50.6% of the applied triclosan was unaccounted for after 12 months either as a consequence of degradation or the formation of non-extractable residues.
显示更多 [+] 显示较少 [-]Seasonal variation in mercury and food web biomagnification in Lake Ontario, Canada
2012
Zhang, Liang | Campbell, Linda M. | Johnson, Timothy B.
Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern Lake Ontario. Hg concentrations, measured in 6 species of invertebrates and 8 species of fishes, tended to be highest in the spring and lowest in the summer for most biota. Yellow perch (Perca flavescens) exhibited significant ontogenetic shifts in diet and Hg, although such patterns were not evident for other species. Food web structure, as indicated by stable isotope values (δ¹⁵N, δ¹³C) was not static. Log-transformed Hg data were strongly and consistently correlated with δ¹⁵N values for the whole food web in each of the three seasons (slopes, 0.17–0.24) and across the entire year (slope, 0.2). While significantly different between seasons, the regression slope values are still consistent with published global Hg biomagnification rates. Our results indicate that the assessment of Hg trends in Great Lakes must take into account seasonal patterns and time of sampling.
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