Deriving ozone dose-response of photosynthesis in adult forest trees from branch-level cuvette gas exchange assessment

Branch-level gas exchange provided the basis for assessing ozone flux in order to derive the dose-response relationship between cumulative O3 uptake (COU) and carbon gain in the upper sun crown of adult Fagus sylvatica. Fluxes of ozone, CO2 and water vapour were monitored simultaneously by climatized branch cuvettes. The cuvettes allowed branch exposure to an ambient or twice-ambient O3 regime, while tree crowns were exposed to the same O3 regimes (twice-ambient generated by a free-air canopy O3 exposure system). COU levels higher than 20mmolm(-2) led to a pronounced decline in carbon gain under elevated O3. The limiting COU range is consistent with findings on neighbouring branches exposed to twice-ambient O3 through free-air fumigation. The cuvette approach allows to estimate O3 flux at peripheral crown positions, where boundary layers are low, yielding a meso-scale within-crown resolution of photosynthetic foliage sensitivity under whole-tree free-air O3 fumigation.     

Detailed analysis of polybrominated biphenyl congeners in bird eggs from Norway

Individual eggs of six species of birds from Norway representing different food chains were analysed for residues of polybrominated biphenyls (PBBs). In all species, the residue pattern was dominated by hexaBBs. The dominating congeners were PBB 153, PBB 154, and PBB 155. Whereas PBB 153 is present in technical hexabromobiphenyl, PBB 154 and PBB 155 are formed by the reductive debromination of decabromobiphenyl. This was evidenced by the detection of several heptaBBs and octaBBs all of which are typical degradation intermediates of PBB 209. Hepta- and octaBBs were more than one order of magnitude less abundant than the hexaBBs. The second most prevailing homologue group was pentaBBs. The most relevant pentabrominated isomers were PBB 99 and PBB 101. Concentrations of the three hexaBBs - PBB 153, PBB 154, and PBB 155 - amounted to 1.3-13 ng/g wet weight or 3-23% of the contamination with polybrominated diphenyl ethers.     

Occurrence and fate of alkylphenols and alkylphenol ethoxylates in sewage treatment plants and impact on receiving waters along the Ter River (Catalonia, NE Spain)

The partitioning of alkylphenols in the dissolved and particulate matter of influents, effluents, accumulation onto sludge and the impact of sewage treatment plant upon receiving waters was studied along the Ter River basin (Catalonia, NE Spain). A solid-phase extraction or pressurized liquid extraction followed by liquid chromatography-mass spectrometry was developed and permitted to determine target compounds with high efficiency in waters, particulate material and sludge. Nonylphenol mono- and diethoxylate, nonylphenol and octylphenol partitioned preferably upon particulate matter and sludge, whereas long chain NPE(3-15)O prevailed in the dissolved phase and was released by effluents. Within the treatment process, a net accumulation of alkylphenols in sludge was found, producing up to 148g/t/month. The removal efficiency of alkylphenols was of 37-90% and depended on the treatment. Assessment on the fate of these contaminants within STPs is discussed in terms of flow rates, biological oxygen demand and tons of sludge produced.     

Atmospheric chemistry of HFE-7000 (CF(3)CF (2)CF (2)OCH (3)) and 2,2,3,3,4,4,4-heptafluoro-1-butanol (CF (3)CF (2)CF (2)CH (2)OH): kinetic rate coefficients and temperature dependence of reactions with chlorine atoms

Background, aim, and scope  The adverse environmental impacts of chlorinated hydrocarbons on the Earth’s ozone layer have focused attention on the effort to replace these compounds by nonchlorinated substitutes with environmental acceptability. Hydrofluoroethers (HFEs) and fluorinated alcohols are currently being introduced in many applications for this purpose. Nevertheless, the presence of a great number of C–F bonds drives to atmospheric long-lived compounds with infrared absorption features. Thus, it is necessary to improve our knowledge about lifetimes and global warming potentials (GWP) for these compounds in order to get a complete evaluation of their environmental impact. Tropospheric degradation is expected to be initiated mainly by OH reactions in the gas phase. Nevertheless, Cl atoms reaction may also be important since rate constants are generally larger than those of OH. In the present work, we report the results obtained in the study of the reactions of Cl radicals with HFE-7000 (CF₃CF₂CF₂OCH₃) (1) and its isomer CF₃CF₂CF₂CH₂OH (2). Materials and methods  Kinetic rate coefficients with Cl atoms have been measured using the discharge flow tube–mass spectrometric technique at 1 Torr of total pressure. The reactions of these chlorofluorocarbons (CFCs) substitutes have been studied under pseudo-first-order kinetic conditions in excess of the fluorinated compounds over Cl atoms. The temperature ranges were 266–333 and 298–353 K for reactions of HFE-7000 and CF₃CF₂CF₂CH₂OH, respectively. Results  The measured room temperature rate constants were k(Cl+CF₃CF₂CF₂OCH₃) = (1.24 ± 0.28) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹and k(Cl+CF₃CF₂CF₂CH₂OH) = (8.35 ± 1.63) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹ (errors are 2σ + 10% to cover systematic errors). The Arrhenius expression for reaction 1 was k ₁(266–333 K) = (6.1 ± 3.8) × 10⁻¹³exp[−(445 ± 186)/T] cm³ molecule⁻¹ s⁻¹ and k ₂(298–353 K) = (1.9 ± 0.7) × 10⁻¹²exp[−(244 ± 125)/T] cm³ molecule⁻¹ s⁻¹ (errors are 2σ). The reactions are reported to proceed through the abstraction of an H atom to form HCl and the corresponding halo-alkyl radical. At 298 K and 1 Torr, yields on HCl of 0.95 ± 0.38 and 0.97 ± 0.16 (errors are 2σ) were obtained for CF₃CF₂CF₂OCH₃ and CF₃CF₂CF₂CH₂OH, respectively. Discussion  The obtained kinetic rate constants are related to the previous data in the literature, showing a good agreement taking into account the error limits. Comparing the obtained results at room temperature, k ₁ and k ₂, HFE-7000 is significantly less reactive than its isomer C₃F₇CH₂OH. A similar behavior has been reported for the reactions of other fluorinated alcohols and their isomeric fluorinated ethers with Cl atoms. Literature data, together with the results reported in this work, show that, for both fluorinated ethers and alcohols, the kinetic rate constant may be considered as not dependent on the number of –CF₂– in the perfluorinated chain. This result may be useful since it is possible to obtain the required physicochemical properties for a given application by changing the number of –CF₂– without changes in the atmospheric reactivity. Furthermore, lifetimes estimations for these CFCs substitutes are calculated and discussed. The average estimated Cl lifetimes are 256 and 38 years for HFE-7000 and C₃H₇CH₂OH, respectively. Conclusions  The studied CFCs’ substitutes are relatively short-lived and OH reaction constitutes their main reactive sink. The average contribution of Cl reactions to global lifetime is about 2% in both cases. Nevertheless, under local conditions as in the marine boundary layer, τ _Cl values as low as 2.5 and 0.4 years for HFE-7000 and C₃H₇CH₂OH, respectively, are expected, showing that the contribution of Cl to the atmospheric degradation of these CFCs substitutes under such conditions may constitute a relevant sink. In the case of CF₃CF₂CF₂OCH₃, significant activation energy has been measured, thus the use of kinetic rate coefficient only at room temperature would result in underestimations of lifetimes and GWPs. Recommendations and perspectives  The results obtained in this work may be helpful within the database used in the modeling studies of coastal areas. The knowledge of the atmospheric behavior and the structure–reactivity relationship discussed in this work may also contribute to the development of new environmentally acceptable chemicals. New volatile materials susceptible of emission to the troposphere should be subject to the study of their reactions with OH and Cl in the range of temperature of the troposphere. The knowledge of the temperature dependence of the kinetic rate constants, as it is now reported for the case of reactions 1 and 2, will allow more accurate lifetimes and related magnitudes like GWPs. Nevertheless, a better knowledge of the vertical Cl tropospheric distribution is still required.     

Endocrine disrupting compounds in municipal and industrial wastewater treatment plants in Northern Greece

The occurrence and fate of endocrine disrupting compounds (EDCs) in a sewage treatment plant and two industrial wastewater treatment plants from textile and tannery factories were investigated. EDCs of interest are 4-nonylphenol, 4-octylphenol, their ethoxylate oligomers (mono- and di-ethoxylates of nonylphenol and octylphenol), bisphenol A, triclosan and steroid estrogens. Target compounds were determined in dissolved fraction, total suspended solids and sludge by employing solid phase extraction and ultrasonication followed by gas chromatography–mass spectrometry.Nonylphenols and oligomers with one or two ethoxy groups were the most abundant compounds in raw wastewater as well as in effluents from all the treatment stages of sewage treatment plant, followed by triclosan and bisphenol A. Steroids were found at very low concentrations. Almost all phenolic EDCs compounds were predominantly associated to suspended solids in influents whereas the dissolved fraction dominated the treated effluents. High removal rates, ranging from 86% to 99%, were observed throughout the whole treatment process. Biodegradation was the main removal pathway of EDCs. Tannery wastewaters exhibited high concentrations of nonylphenolic compounds. This type of wastewaters could pose a significant risk to the aquatic and terrestrial environment.     

Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance

Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO(2) and CH(4) causing a net release of CO(2) and CH(4) to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO(2) and CH(4)) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange.     

Preconcentration technique for the determination of trace elements in natural water samples by ICP-AES

A procedure was developed for the determination of Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) after preconcentration on a morpholine dithiocarbamate (mor-DTC) supported by bagasse (Saccharam aphisinaram). The sorbed elements were subsequently eluted with 4,M HNO₃ and the acid eluates were analysed by ICP–AES. The influence of various parameters such as pH, flow rate of sample, eluent concentration, volume of the sample and volume of eluent were investigated to enhance the sensitivity of the present method. A 20,mL disposable syringe served as preconcentration column. Under the optimal conditions Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in aqueous sample was concentrated about 100-fold. The sorption recoveries of elements were higher than 99.6%. The method is also applied for the analysis of natural and spiked water samples.     

Post-mating odor in females of the solitary bee, Andrena nigroaenea (Apoidea, Andrenidae), inhibits male mating behavior

We investigated odor changes and their behavioral significance in the solitary, ground-nesting bee Andrena nigroaenea. We used gas chromatography with electroantennographic detection and performed behavioral tests with males in the field using natural odor samples and synthetic compounds. We found that only cuticle extracts of young females elicited copulation attempts in the males. We demonstrated that among the 17 compounds which triggered electroantennographic responses, all-trans-farnesyl hexanoate and all-trans-farnesol were significantly more abundant in unattractive cuticle extracts of A. nigroaenea females. Dufour’s gland extracts of these females also contained greater amounts of both compounds. In bioassays using synthetic farnesyl hexanoate and farnesol we found that these compounds inhibit copulation behavior in the males. Farnesyl hexanoate is probably synthesized in Dufour’s gland and used by females for lining brood cells. We interpret the semiochemical function of farnesyl hexanoate and its precursor farnesol to have evolved secondarily. As an outcome of sexual selection, it facilitates the discrimination by males of receptive females from nesting and thus already mated individuals. The dual function of these compounds represents an elegant parsimony in the chemical communication system of this insect. Received: 19 January 2000 / Revised: 29 May 2000 / Accepted: 24 June 2000     

Lead (Pb) isotopic fingerprinting and its applications in lead pollution studies in China: A review

As the most widely scattered toxic metal in the world, the sources of lead (Pb) observed in contamination investigation are often difficult to identify. This review presents an overview of the principles, analysis, and applications of Pb isotopic fingerprinting in tracing the origins and transport pathways of Pb in the environment. It also summarizes the history and current status of lead pollution in China, and illustrates the power of Pb isotopic fingerprinting with examples of its recent applications in investigating the effectiveness of leaded gasoline phase-out on atmospheric lead pollution, and the sources of Pb found in various environmental media (plants, sediments, and aquatic organisms) in China. The limitations of Pb isotopic fingerprinting technique are discussed and a perspective on its development is also presented. Further methodological developments and more widespread instrument availability are expected to make isotopic fingerprinting one of the key tools in lead pollution investigation.     

On-Site Gas Chromatography/Mass Spectrometry (GC/MS) Analysis to Streamline Vapor Intrusion Investigations

Distinguishing between vapor intrusion and indoor sources of volatile organic compounds (VOCs) is a significant challenge in conventional vapor intrusion assessments. For this research project, the authors developed a step-by-step protocol to streamline building-specific investigations by using on-site gas chromatography/mass spectrometry (GC/MS) analysis and building pressure manipulation to determine the source of VOCs in indoor air during a 1-day field investigation. Protocol validation included implementation in industrial buildings and testing alongside conventional methods. The new protocol compares favorably to conventional approaches, yielding more definitive results in less time. This article presents three case studies which illustrate application of the protocol.