Wet deposition of poly- and perfluorinated compounds in Northern Germany

Twenty precipitation samples were taken concurrently with air samples at a northern German monitoring site over a period of 7 months in 2007 and 2008. Thirty four poly- and perfluorinated compounds (PFC) were determined in rain water samples by solid phase extraction and HPLC-MS/MS analysis. Seventeen compounds were detected in rain water with ΣPFC concentrations ranging from 1.6 ng L⁻¹ to 48.6 ng L⁻¹. Perfluorooctanoate (PFOA) and perfluorobutanate (PFBA) were the compounds that were usually observed in highest concentrations. Calculated ΣPFC deposition rates were between 2 and 91 ng m⁻² d⁻¹. These findings indicate that particle phase PFC are deposited from the atmosphere by precipitation. A relationship between PFC wet deposition and air concentration may be established via precipitation amounts. Trajectory analysis revealed that PFC concentration and deposition estimates in precipitation can only be explained if a detailed air mass history is considered.     

Rates of particulate pollution deposition onto leaf surfaces: Temporal and inter-species magnetic analyses

Evaluation of health impacts arising from inhalation of pollutant particles <10 μm (PM₁₀) is an active research area. However, lack of exposure data at high spatial resolution impedes identification of causal associations between exposure and illness. Biomagnetic monitoring of PM₁₀ deposited on tree leaves may provide a means of obtaining exposure data at high spatial resolution. To calculate ambient PM₁₀ concentrations from leaf magnetic values, the relationship between the magnetic signal and total PM₁₀ mass must be quantified, and the exposure time (via magnetic deposition velocity (MV_d) calculations) known. Birches display higher MV_d (∼5 cm⁻¹) than lime trees (∼2 cm⁻¹). Leaf saturation remanence values reached ‘equilibrium’ with ambient PM₁₀ concentrations after ∼6 ‘dry’ days (<3 mm/day rainfall). Other co-located species displayed within-species consistency in MV_d; robust inter-calibration can thus be achieved, enabling magnetic PM₁₀ biomonitoring at unprecedented spatial resolution.     

中国城乡一体化水平的省区分异

推进形成城乡经济社会发展一体化新格局,是全面建设小康社会、实现城乡社会经济发展方式转型的重要举措。本文采用城乡发展差异系数、城乡一体化水平指数等指标,分析了中国城乡一体化水平的省区差异,揭示了这种地域分异所产生的影响因素,进一步探讨推进全国城乡一体化新格局形成的科学机制。研究表明,中国城乡发展无论是东部相对发达省区,还是西部欠发展省区,差异显著,呈现不均衡特点;城乡一体化水平受自然环境、经济社会发展综合实力和公共政策等因素影响明显;加快建构城乡一体化发展新格局,需要进一步纠正"城市偏向"的发展观,加大城乡统筹力度,推进城乡基本公共服务均等化进程,并根据变化趋势,调整公共政策的着力点,提升城乡一体化发展的区域协调性。     

Ozone flux over a Norway spruce forest and correlation with net ecosystem production

Daily ozone deposition flux to a Norway spruce forest in Czech Republic was measured using the gradient method in July and August 2008. Results were in good agreement with a deposition flux model. The mean daily stomatal uptake of ozone was around 47% of total deposition. Average deposition velocity was 0.39 cm s⁻¹ and 0.36 cm s⁻¹ by the gradient method and the deposition model, respectively. Measured and modelled non-stomatal uptake was around 0.2 cm s⁻¹. In addition, net ecosystem production (NEP) was measured by using Eddy Covariance and correlations with O₃ concentrations at 15 m a.g.l., total deposition and stomatal uptake were tested. Total deposition and stomatal uptake of ozone significantly decreased NEP, especially by high intensities of solar radiation.     

Potential mechanisms of phthalate ester embryotoxicity in the abalone Haliotis diversicolor supertexta

The effects and associated toxicological mechanisms of five phthalate esters (PAEs) on abalone embryonic development were investigated by exposing the embryos to a range of PAEs concentrations (0.05, 0.2, 2 and 10 μg/mL). The results showed that PAEs could significantly reduce embryo hatchability, increase developmental malformations, and suppress the metamorphosis of abalone larvae. The possible toxicological mechanisms of PAEs to abalone embryos included, affecting the Na⁺-K⁺-pump and Ca²⁺-Mg²⁺-pump activities, altering the peroxidase (POD) level and the malondialdehyde (MDA) production, damaging the extraembryonic membranes structure, as well as disrupting endocrine-related genes (gpx, cyp3a, and 17β-hsd 12) expression properties. Taken together, this work showed that PAEs adversely affected the embryonic ontogeny of abalone. The abilities of PAEs affecting the osmoregulation, inducing oxidative stress, damaging embryo envelope structure, and causing physiological homeostasis disorder, are likely to be a part of the common mechanisms responsible for their embryonic toxicity.     

Response of non-enzymatic antioxidative mechanisms to stress caused by infection with Fusarium fungi and chemical protection in different wheat genotypes

The aim of this study was to assess the effect of infection with Fusarium fungi and chemical protection on the contents of phenolic acids and antioxidative potential of extracts from grains of 23 wheat genotypes. Based on chemical analyses including abiotic factors such as weather conditions and the location of the plantation, the authors attempted to clarify non-enzymatic antioxidative response mechanisms to two different stressors in 23 wheat genotypes. Based on chemical analysis, it was found that mass infection with fungi from the genus Fusarium induces defence mechanisms of the plant, which results in an increased production of phenolic acids, mainly those, which are substrates for the production of acids exhibiting antimicrobial action. This mechanism is confirmed by the analyses of antioxidant activity, which also increases significantly during fungal infection, connected with the production of mycotoxins. In the course of chemical plant protection, significant changes were observed in the production of phenolic acids. Even if antioxidant activity was not higher in comparison to the control, an increased production of certain phenolic acids was recorded, which suggests stimulation of the resistance system of the plant, at a simultaneous complete response of antioxidative mechanisms, as it takes place during fungal infection.     

Thermal degradation kinetics and mechanisms of Posidonia Oceanica under inert and oxidative atmospheres

The thermal degradation characteristics of Posidonia Oceanica (PO), a marine biomass abundantly available on the coastal zone of the Mediterranean Basin, were investigated using thermogravimetric analysis under inert and oxidative atmospheres. The kinetic parameters of the both thermal degradations conditions were determined using n-reaction order model. Coats–Redfern and Phadnis–Deshpande methods were used to discuss the probable degradation mechanisms. Results showed that PO is an attractive alternative for energy production owing to its elevated heating value. Moreover, PO thermal degradation follows the usual shape of biomass decomposition. Hence, under inert atmosphere, its thermal degradation had two different stages after moisture release. The first stage corresponded to the volatiles release while the second stage corresponded to the char formation. The solid-state decomposition mechanisms followed by the devolatilization step of PO were two or three dimensional diffusion controlled reaction. However, the decomposition mechanism during PO char formation corresponded to a nucleation and growth mechanism. Under oxidative atmosphere, two stages were also observed corresponding to volatiles release and char combustion, respectively. The solid-state mechanism of volatiles release followed three dimensional diffusion controlled reaction while the char combustion mechanism corresponded to a contracting area phase boundary controlled reaction.     

Tritium profiles in snowpacks

The release of tritiated water (HTO) to the atmosphere during the winter can contribute significantly to snow contamination and to water-soil-plant contamination after the spring thaw. The dose significance of such a release depends on the persistence of tritiated water in the snowpack, which is primarily controlled by the HTO diffusion process in snow and the rate of re-emission into the atmosphere from the snowpack surface. Monitoring data collected after an acute winter release at Chalk River Laboratories and data obtained in winter over a chronically contaminated area were analyzed to estimate the diffusion coefficient of HTO in the snowpack. Under conditions of cold and dry snow, the diffusion coefficient lay in the range 1-2 × 10⁻¹⁰ m² s⁻¹, an order of magnitude lower than diffusion in water but an order of magnitude higher than self-diffusion in ice. These results confirm the theoretical predictions (Bales, 1991). Values up to six times higher were found for warmer periods and just before spring melt, when other processes contribute to profile evolution. The low diffusion rate of tritium in cold, dry snow means that tritium remains in the snowpack throughout the winter, to be released during spring thaw to potentially contaminate surface water, soil and crops.     

Reduced mercury deposition in New Hampshire from 1996 to 2002 due to changes in local sources

Changes in deposition of gaseous divalent mercury (Hg(II)) and particulate mercury (Hg(p)) in New Hampshire due to changes in local sources from 1996 to 2002 were assessed using the Industrial Source Complex Short Term (ISCST3) model (regional and global sources and Hg atmospheric reactions were not considered). Mercury (Hg) emissions in New Hampshire and adjacent areas decreased significantly (from 1540 to 880 kg yr⁻¹) during this period, and the average annual modeled deposition of total Hg also declined from 17 to 7.0 μg m⁻² yr⁻¹ for the same period. In 2002, the maximum amount of Hg deposition was modeled to be in southern New Hampshire, while for 1996 the maximum deposition occurred farther north and east. The ISCST3 was also used to evaluate two future scenarios. The average percent difference in deposition across all cells was 5% for the 50% reduction scenario and 9% for the 90% reduction scenario.     

Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area

Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle + gas) ∑₄₁-PCB concentrations were higher in summer (3370 ± 1617 pg m⁻³, average + SD) than in winter (1164 ± 618 pg m⁻³), probably due to increased volatilization with temperature. Average particulate ∑₄₁-PCBs dry deposition fluxes were 349 ± 183 and 469 ± 328 ng m⁻² day⁻¹ in summer and winter, respectively. Overall average particulate deposition velocity was 5.5 ± 3.5 cm s⁻¹. The spatial distribution of ∑₄₁-PCB soil concentrations (n = 48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.