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Supercritical fluid extraction of persistent organic pollutants from natural and artificial soils and comparison with bioaccumulation in earthworms
2013
Bielská, Lucie | Šmídová, Klára | Hofman, Jakub
Selective supercritical fluid extraction (SSFE) was used as a measurement of compound chemical accessibility and as a predictor of compound bioavailability from three natural soils and artificial analogues prepared to have comparable total organic carbon content. Soils spiked with phenanthrene, pyrene, PCB 153, lindane, and p,p′-DDT were aged for 0, 14, 28, or 56 days and then selectively extracted by supercritical fluid extraction. Compounds exhibited decreasing extractability with increasing pollutant–soil contact time and increasing total organic carbon content in tested soils. However, the different extractability of compounds from artificial and natural pairs having comparable TOC indicates the limitations of using TOC as an extrapolation basis between various soils. The comparison of extractability with bioaccumulation by earthworms (Eisenia fetida) previously published by Vlčková and Hofman (2012) showed that only for PAHs it was possible to predict their bioaccumulation by means of selective SFE.
Mostrar más [+] Menos [-]Influence of age, sex and breeding status on mercury accumulation patterns in the wandering albatross Diomedea exulans
2013
Tavares, S. | Xavier, J.C. | Phillips, R.A. | Pereira, M.E. | Pardal, M.A.
Although mercury bio-amplifies through the food chain and accumulates in top predators, mercury concentrations in tissues of the wandering albatross are greater than in any other vertebrate, including closely related species. In order to explore the alternative explanations for this pattern, we measured total mercury concentrations in feathers, plasma and blood cells of wandering albatrosses of known age, sex and breeding status sampled at South Georgia. Mercury concentrations were low in feathers and blood components of chicks, and higher in the feathers of young pre-breeders than in feathers or blood of older pre-breeders and breeding adults. There was no effect of sex on mercury concentrations in the feathers of pre-breeders or breeding adults, whereas levels were significantly higher in blood cells of breeding females than males. The high feather mercury concentrations of young pre-breeders compared with older birds suggest an increase in moult frequency as birds approach maturity.
Mostrar más [+] Menos [-]Phytotoxicity and oxidative stress effect of 1-octyl-3-methylimidazolium chloride ionic liquid on rice seedlings
2013
Liu, Huijun | Zhang, Shuxian | Hu, Xiaona | Chen, Caidong
The effects of the ionic liquid 1-octyl-3-methylimidazolium chloride ([OMIM]Cl) was studied in hydroponically grown rice seedlings. Observed effects included increased root length and weight at concentrations of 0.1 mg/L [OMIM]Cl, however, as concentrations increased a reversed response was observed where roots and stems grew shorter and the weight decreased. The inhibitory concentration 50 (IC50,5d) values for root length and stem length were 0.59 mg/L and 0.70 mg/L, respectively. The Hill reaction activity and root system activity in [OMIM]Cl-treated rice seedlings were observed to be lower than the controls, however, root membrane permeability increased. The antioxidant enzyme activity in roots decreased, while in leaves there was an initial stimulation followed by a decrease. Malondialdehyde (MDA) content was found to be greater in seedlings subjected to [OMIM]Cl treatment. The cellular structures, such as chloroplasts, mitochondria and rough endoplasmic reticulum in rice root and leaf cells were affected at concentrations of 0.6 mg/L [OMIM]Cl.
Mostrar más [+] Menos [-]Quantitative analysis on the urban flood mitigation effect by the extensive green roof system
2013
Lee, J.Y. | Moon, H.J. | Kim, T.I. | Kim, H.W. | Han, M.Y.
Extensive green-roof systems are expected to have a synergetic effect in mitigating urban runoff, decreasing temperature and supplying water to a building. Mitigation of runoff through rainwater retention requires the effective design of a green-roof catchment. This study identified how to improve building runoff mitigation through quantitative analysis of an extensive green-roof system. Quantitative analysis of green-roof runoff characteristics indicated that the extensive green roof has a high water-retaining capacity response to rainfall of less than 20 mm/h. As the rainfall intensity increased, the water-retaining capacity decreased. The catchment efficiency of an extensive green roof ranged from 0.44 to 0.52, indicating reduced runoff comparing with efficiency of 0.9 for a concrete roof. Therefore, extensive green roofs are an effective storm water best-management practice and the proposed parameters can be applied to an algorithm for rainwater-harvesting tank design.
Mostrar más [+] Menos [-]Life-history effects of arsenic toxicity in clades of the earthworm Lumbricus rubellus
2013
Anderson, C.J. | Kille, P. | Lawlor, A.J. | Spurgeon, D.J.
Exposures of Lumbricus rubellus to a series of arsenic concentrations in soil were used to assess life-stage (juvenile, adult) and genotype specific sensitivities, to calculate population growth rate (λ) and to assess patterns of As accumulation. Significant mortality was seen in juveniles at 125 mg/kg As, while growth and maturation was affected from 36 mg/kg and above. In adults, cocoon production at the highest concentration (125 mg/kg) was significantly reduced. Phylogenetic analysis was performed by comparison of mitochondrial sequences to establish genotypic variation among juveniles. Three clades with more than 7.5% divergent were described, with 70% of earthworms belonging to a single clade. Date of and mass at maturation was significantly different between clades, but clades were not differentially As sensitive. Parameter λ was reduced at 36 mg/kg As and was negative at 125 mg/kg As, suggesting impacts and population stability and potential extinction at environmentally relevant concentrations.
Mostrar más [+] Menos [-]Biodegradation of 17α-ethinylestradiol by heterotrophic bacteria
2013
Larcher, Simone | Yargeau, Viviane
The presence of the synthetic estrogen 17α-ethinylestradiol (EE2) in the environment is of increasing concern due to the endocrine disruption of aquatic organisms. Incomplete removal from wastewater (WW) is one of the main sources of EE2 in aquatic ecosystems, thus improving processes like biological WW treatment/activated sludge (AS) is becoming significantly important. There are opposing results regarding EE2 biodegradability by AS; one discrepancy is the efficacy of heterotrophic bacteria. This research demonstrated the ability of heterotrophs commonly present in AS (B. subtilis, P. aeruginosa, P. putida, R. equi, R. erythropolis, R. rhodochrous, R. zopfii) to remove EE2. R. rhodochrous was the most successful with no detectable EE2 after 48 h; the other bacteria achieved 21%–61% EE2 removal. No additive or synergistic effects were observed due to the combination of the bacterial cultures with maximum EE2 removals of 43% after 300 h.
Mostrar más [+] Menos [-]A review of metal (Pb and Zn) sensitive and pH tolerant bioassay organisms for risk screening of metal-contaminated acidic soils
2013
Chapman, E.Emily V. | Dave, Göran | Murimboh, John D.
To improve risk estimates at the screening stage of Ecological Risk Assessment (ERA), short duration bioassays tailored to undisturbed soil cores from the contaminated site could be useful. However, existing standardized bioassays use disturbed soil samples and often pH sensitive organisms. This is a problem as naturally acidic soils are widespread. Changing soil properties to suit the test organism may change metal bioavailability, leading to erroneous risk estimates. For bioassays in undisturbed soil cores to be effective, species able to withstand natural soil properties must be identified. This review presents a critical examination of bioassay species' tolerance of acidic soils and sensitivity to metal contaminants such as Pb and Zn. Promising organisms include; Dendrobaena octaedra, Folsomia candida, Caenorhabditis elegans, Oppia nitens, Brassica rapa, Trifolium pratense, Allium cepa, Quercus rubra and Acer rubrum. The MetSTICK test and the Bait lamina test were also identified as suitable microorganism tests.
Mostrar más [+] Menos [-]Molecular biomarkers for sources of organic matter in lacustrine sediments in a subtropical lake in China
2013
Wang, Yan-Hua | Yang, Hao | Chen, Xia | Zhang, Ji-Xiang | Ou, Jie | Xie, Biao | Huang, Chang-Chun
N-alkanes distributions and stable isotopic compositions (δ13C and δ15N) in the lacustrine sediments of Shijiu lake were measured to assess whether biological source information was recorded in the molecular biomarker. Results showed regular unimodal n-alkanes distribution in range of C16–C33 with strong predominance of odd-numbered n-alkanes, maximizing at C29. The δ15N for SON were uniformly low, ranging from −6.7‰ to 3.8‰ and C/N ratios ranged from 6.6 to 10.0, suggesting that most of organic matter was influenced by terrestrial characteristics of the watershed. The δ13C for C27 to C31n-alkanes and for SOC varied from −32.9‰ to −26.6‰ and −23.4‰ to −21.6‰, respectively, falling within the range of corresponding n-alkanes in leaves mainly from C3 land plants. The values of C/N, CPI, OEP, ACL and C27/C31 exhibit similar temporal changes with the primary production, showing enhanced eutrophication resulted from increased anthropogenic activities in Shijiu lake from 1852 to 2010.
Mostrar más [+] Menos [-]Application of compound-specific stable carbon isotope analysis for the biotransformation and trophic dynamics of PBDEs in a feeding study with fish
2013
Luo, Xiao-Jun | Zeng, Yan-Hong | Chen, Hua-Shan | Wu, Jiang-Ping | Chen, She-Jun | Mai, Bi-Xian
The debromination and trophic dynamics of PBDEs in fish and whether or not compound-specific isotopic analysis (CSIA) can be used to trace these processes were investigated. Two predator/prey relationships were established in laboratory by two predatory fish species, oscar fish (OF) and redtail catfish (RF) feeding on tiger barb (TB) exposed to a commercial PBDE mixture. Metabolic debromination of PBDEs was observed in the TB and the OF, but not in the RF. The calculated biomagnification factors (BMFs) were uniform for most of the congeners in RF/TB but varied in OF/TB, which can be attributed to the metabolic debromination in the OF. The δ13C values of BDE47 and BDE28 were lower in fish than in those in the commercial mixture but the δ13C values of BDE99 were slightly higher. These results indicated that CSIA can be used to trace the biotransformation of PBDEs in biota.
Mostrar más [+] Menos [-]Modelling metal–metal interactions and metal toxicity to lettuce Lactuca sativa following mixture exposure (Cu2+–Zn2+ and Cu2+–Ag+)
2013
Le, T.T Yen | Vijver, Martina G. | Kinraide, Thomas B. | Peijnenburg, Willie J.G.M. | Hendriks, A Jan
Metal toxicity to lettuce Lactuca sativa was determined following mixture exposure based on the concepts of concentration addition (CA) and response addition (RA). On the basis of conventional models assuming no interaction between mixture components, Ag+ was the most toxic, followed by Cu2+ and Zn2+. Furthermore, ion–ion interactions were included in quantitatively estimating toxicity of interactive mixtures of Cu2+–Zn2+ and Cu2+–Ag+ by linearly expanding the CA and RA models. About 80–92% of the variability in the root growth could be explained by this approach. Estimates by the extended models indicate significant alleviative effects of Zn2+ on Cu2+ toxicity whereas Cu2+ did not significantly affect Zn2+ toxicity. According to the extended CA model, Cu2+ significantly reduced Ag+ toxicity while Ag+ enhanced Cu2+ toxicity. Similar effects were not found by the extended RA model. These interactions might result from their individual uptake mechanisms and toxic actions as published in literature.
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