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Concentration responses to organochlorines in Phragmites australis
2012
Faure, Mathieu | San Miguel, Angélique | Ravanel, Patrick | Raveton, Muriel
Phragmites australis shows potential for the phytoremediation of chlorinated chemicals. Also there has been some attempt to determine the phytotoxic effects of organochlorines (OC). This study reports for lindane (HCH), monochlorobenzene (MCB), 1,4-dichlorobenzene (DCB) and 1,2,4-trichlorobenzene (TCB), a no-observed-effect-concentration (NOEC₇d) that was 1000–300,000 times higher than environmental concentrations. Nevertheless, the combined OC mixture (NOEC₇d level of each congener) induced a synergistic toxic effect, causing a severe drop (70%) in chlorophyll concentration. The mixture 0.2mgL⁻¹ MCB+0.2mgL⁻¹ DCB+2.5mgL⁻¹ TCB+0.175mgL⁻¹ HCH, that was 15 times more concentrated than environmental OC mixture, did not cause phytotoxicity during 21 days. Antioxidant enzymes were affected immediately after the start of exposure (3 days), but the plants showed no signs of stress thereafter. These data suggest that environmental OC mixtures do not pose a significant risk to P. australis.
显示更多 [+] 显示较少 [-]Air–soil exchange of PCBs: Seasonal variations in levels and fluxes with influence of equilibrium conditions
2012
Tasdemir, Yücel | Salihoglu, Güray | Salihoglu, Nezih Kamil | Birgül, Askın
The variations in the occurrences of PCB congeners both in soil and air were investigated in conjunction with each other, and the changes in the fugacity fractions and flux levels were examined on a seasonal basis. Air and soil samples were collected concurrently two or three times in a month during a one-year monitoring at two different locations in Bursa, located in the northwestern Turkey. Fugacity fractions and net flux levels of PCB congeners were calculated. Air and soil PCB levels increased together as the soil temperature increased, suggesting the influence of instantaneous air–soil exchange towards the equilibrium conditions. The flux levels and fugacity fractions also showed a positive significant correlation with soil temperature. Flux levels were positive for the dates with fugacity fractions above 0.5, indicating volatilization from soil to air.
显示更多 [+] 显示较少 [-]Modeling the kinetics of microbial degradation of deicing chemicals in porous media under flow conditions
2012
Wehrer, Markus | Jaesche, Philipp | Totsche, Kai Uwe
A quantitative knowledge of the fate of deicing chemicals in the subsurface can be provided by joint analysis of lab experiments with numerical simulation models. In the present study, published experimental data of microbial degradation of the deicing chemical propylene glycol (PG) under flow conditions in soil columns were simulated inversely to receive the parameters of degradation. We evaluated different scenarios of an advection-dispersion model including different terms for degradation, such as zero order, first order and inclusion of a growing and decaying biomass for their ability to explain the data. The general break-through behavior of propylene glycol in soil columns can be simulated well using a coupled model of solute transport and degradation with growth and decay of biomass. The susceptibility of the model to non-unique solutions was investigated using systematical forward and inverse simulations. We found that the model tends to equifinal solutions under certain conditions.
显示更多 [+] 显示较少 [-]Trend and concentrations of legacy lead (Pb) in highway runoff
2012
Kayhanian, Masoud
This study presents the results of lead (Pb) concentrations from both highway runoff and contaminated soil along 32 and 23 highway sites, respectively. In general, the Pb concentration on topsoil (0–15 cm) along highways was much higher than the Pb concentration in subsurface soil (15–60 cm). The Pb deposited on soil appears to be anthropogenic and a strong correlation was found between the Pb concentration in surface soil and highway runoff in urban areas. The concentration of Pb measured during 1980s from highways runoff throughout the world was up to 11 times higher than the measured values in mid 1990s and 2000s. The current Pb deposited on soil near highways appears to be a mixture of paint, tire weight balance and old leaded gasoline combustion. Overall, the Pb phase-out regulation reduced the Pb deposits in the environment and consequently lowered Pb loading into receiving waters.
显示更多 [+] 显示较少 [-]Occurrence and persistence of organic emerging contaminants and priority pollutants in five sewage treatment plants of Spain: Two years pilot survey monitoring
2012
Bueno, M.J Martínez | Gomez, M.J. | Herrera, S. | Hernando, M.D. | Agüera, A. | Fernández-Alba, A.R.
This work summarized all results obtained during almost two-years of a monitoring programme carried out in five municipal sewage treatment plants (STPs) located in the north, centre and south-east of Spain. The study evaluated the occurrence and persistence of a group of 100 organic compounds belonging to several chemical groups (pharmaceuticals, personal care products, pesticides and metabolites). The average removal efficiencies of the STPs studied varied from 20% (erythromycin) to 99% (acetaminophen). In analysed samples, we identified a large number of compounds at mean range concentrations between 7–59,495 ng/L and 5–32,720 ng/L for influent and effluent samples, respectively. This study also identified 20 of the mostly detected and persistent compounds in wastewater effluent, of which hydrochlorothiazide, atenolol, gemfibrozil, galaxolide and three metabolites (fenofibric acid, 4-AAA and 4-FAA), presented the highest average contribution percentages, in relation to the total load of contaminants for the different STPs effluent studied.
显示更多 [+] 显示较少 [-]Assessment of polybrominated diphenyl ethers (PBDEs) in serum from the Korean general population
2012
Kim, Jongchul | Kang, Jung-Ho | Park, Hyokeun | Baek, Song-Yee | Kim, Yang-ho | Chang, Yoon Seok
In 2009 and 2010, 720 serum samples were collected from non-occupationally exposed study participants at four Korean locations and monitored for the presence of 27 polybrominated diphenyl ether (PBDE) congeners. The median concentrations of Σ₂₇PBDEs (the sum of 27 congeners) and Σ₃–₇PBDEs (the sum of tri- to hepta-BDE congeners) were 6.04 and 4.97 ng/g lipid, respectively. The most abundant congener detected in serum samples was BDE-153, followed by BDE-47 and BDE-99. The median value of Σ₃–₇PBDEs was similar to the median values observed in Asia and Europe, but much lower than that observed in North America. Some significant differences, based on geographic region and sex, were observed. We also observed a positive increase of BDE-153 with regard to age. In addition, we estimated the daily exposure to PBDEs from previously published reports of PBDE concentrations in food and dust, and determined the individual contributions of a variety of sources.
显示更多 [+] 显示较少 [-]Toxicity of copper nanoparticles and CuCl₂ salt to Enchytraeus albidus worms: Survival, reproduction and avoidance responses
2012
Amorim, Mónica João Barros | Scott-Fordsmand, Janeck James
Environmental effects of copper nanoparticles are little studied in terrestrial ecosystems. In the present article, the toxicity of copper nanoparticles (Cu-NP) on the enchytraeid Enchytraeus albidus is compared to the toxicity of a copper-salt (CuCl₂). The effect parameters studied were survival, reproductive output and avoidance behaviour. The results show that Cu-NP were more toxic to E. albidus than the same concentrations of the CuCl₂-salt. The physic-chemical analysis of the particles indicated that only a small fraction was released as ions. Hence, the results indicated a nanoparticle-specific effect – lower reproductive output and higher avoidance. This was observed as 2–8 fold (significant) lower ECx values for Cu-NP (EC₅₀₋ᵣₑₚᵣₒd = 95 mg Cu/kg; EC₅₀₋ₐᵥₒᵢd = 241 mg Cu/kg) exposed organisms compared to CuCl₂ (EC₅₀ ₋ ᵣₑₚᵣₒd = 251 mg Cu/kg; EC₅₀₋ₐᵥₒᵢd = 475 mg Cu/kg) exposed organisms. These results corroborate with a nanoparticle-specific effect.
显示更多 [+] 显示较少 [-]Responses of native broadleaved woody species to elevated ozone in subtropical China
2012
Zhang, Weiwei | Feng, Zhaozhong | Wang, Xiaoke | Niu, Junfeng
To assess ozone sensitivity of subtropical broadleaved tree species and explore possible underlying mechanisms, six evergreen and two deciduous native species were exposed to either charcoal-filtered air or elevated O₃ (E-O₃, ∼150ppb) for one growing season. Initial visible symptoms in deciduous species appeared much earlier than those in evergreen species. The species which first showed visible symptoms also had the largest reductions in biomass. E-O₃ induced significant decreases in photosynthesis rate, chlorophyll content and antioxidant capacity but a significant increase in malondialdehyde content in two deciduous species and two evergreen species (Cinnamomum camphora and Cyclobalanopsis glauca). Except C. glauca, however, E-O₃ had no significant effects on stomatal conductance (gₛ), total phenols and ascorbate contents. Difference in O₃ sensitivity among all species was strongly attributed to specific leaf mass rather than gₛ. It suggests that some subtropical tree species will be threatened by rising O₃ concentrations in the near future.
显示更多 [+] 显示较少 [-]Contaminant exposure in relation to spatio-temporal variation in diet composition: A case study of the little owl (Athene noctua)
2012
Schipper, Aafke M. | Wijnhoven, Sander | Baveco, Hans | Brink, Nico W. van den
We assessed dietary exposure of the little owl Athene noctua to trace metal contamination in a Dutch Rhine River floodplain area. Diet composition was calculated per month for three habitat types, based on the population densities of six prey types (earthworms, ground beetles and four small mammal species) combined with the little owl’s functional response to these prey types. Exposure levels showed a strong positive relationship with the dietary fraction of earthworms, but also depended on the dietary fraction of common voles, with higher common vole fractions resulting in decreasing exposure levels. Spatio-temporal changes in the availability of earthworms and common voles in particular resulted in considerable variation in exposure, with peaks in exposure exceeding a tentative toxicity threshold. These findings imply that wildlife exposure assessments based on a predefined, average diet composition may considerably underestimate local or intermittent peaks in exposure.
显示更多 [+] 显示较少 [-]Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions
2012
Charlestra, Lucner | Amirbahman, Aria | Courtemanch, David L. | Alvarez, David A. | Patterson, Howard
The polar organic chemical integrative sampler (POCIS) was calibrated to monitor pesticides in water under controlled laboratory conditions. The effect of natural organic matter (NOM) on the sampling rates (Rₛ) was evaluated in microcosms containing <0.1–5 mg L⁻¹ of total organic carbon (TOC). The effect of hydrodynamics was studied by comparing Rₛ values measured in stirred (SBE) and quiescent (QBE) batch experiments and a flow-through system (FTS). The level of NOM in the water used in these experiments had no effect on the magnitude of the pesticide sampling rates (p > 0.05). However, flow velocity and turbulence significantly increased the sampling rates of the pesticides in the FTS and SBE compared to the QBE (p < 0.001). The calibration data generated can be used to derive pesticide concentrations in water from POCIS deployed in stagnant and turbulent environmental systems without correction for NOM.
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