Methyl bromide (CH3Br) is the most abundant brominated organic compound in the atmosphere. It is known to originate from natural and anthropogenic sources, although many uncertainties remain regarding strengths of both sources and sinks and the processes leading to its formation. In this study a potential new CH3Br source from vegetation has been examined, analogous to the recently discovered abiotic formation of methyl chloride from plant pectin. Several plant samples with known bromine content, including ash (Fraxinus excelsior), saltwort (Batis maritima), tomato reference material (NIST-1573a), hay reference material (IAEA V-10), and also bromine enriched pectin, were incubated in the temperature range of 25-50 degrees C and analyzed for CH3Br emission using gas chromatography/mass spectrometry. All plant samples inspected showed an exponential increase in CH3Br emission as a function of temperature increase, i.e., emissions were observed to approximately double with every 5 degrees C rise in temperature. Next to temperature, it was found that emissions of CH3Br were also dependent on the bromine content of the plants. The highest CH3Br release rates were found for the saltwort which contained the highest bromine concentration. Arrhenius plots confirmed that the observed emissions were from an abiotic origin. The contribution of abiotic CH3Br formation from vegetation to the global budget will vary geographically as a result of regional differences in both temperature and bromide content of terrestrial plants.

The claim of methane (CH4) formation in plants has caused much controversy and debate within the scientific community over the past 4 years. Here, using both stable isotope and concentration measurements, we demonstrate that CH4 formation occurs in plant cell cultures that were grown in the dark under sterile conditions. Under non-stress conditions the plant cell cultures produced trace amounts [0.3-0.6 ng g -1 dry weight (DW) h -1 ] of CH4 but these could be increased by one to two orders of magnitude (up to 12 ng g -1 DW h -1 ) when sodium azide, a compound known to disrupt electron transport flow at the cytochrome c oxidase (complex IV) in plant mitochondria, was added to the cell cultures. The addition of other electron transport chain (ETC) inhibitors did not result in significant CH4 formation indicating that a site-specific disturbance of the ETC at complex IV causes CH4 formation in plant cells. Our study is an important first step in providing more information on non-microbial CH4 formation from living plants particularly under abiotic stress conditions that might affect the electron transport flow at the cytochrome c oxidase in plant mitochondria.

The effect of high dietary levels of arachidonic acid (ARA) on the eye migration and cranial bone remodelling processes in Senegalese sole Solea senegalensis early juveniles (age: 50 days post hatch) was evaluated by means of geometric morphometric analysis and alizarin red staining of cranial skeletal elements. The incidence of normally pigmented fish fed the control diet was 99·1 ± 0·3% (mean ± s.e.), whereas it was only 18·7 ± 7·5% for those fed high levels of ARA (ARA-H). The frequency of cranial deformities was significantly higher in fish fed ARA-H (95·1 ± 1·5%) than in those fed the control diet (1·9 ± 1·9%). Cranial deformities were significantly and negatively correlated with the incidence of normally pigmented animals (r² = -0·88, P < 0·001, n = 16). Thus, fish displaying pigmentary disorders differed in the position of their eyes with regard to the vertebral column and mouth axes, and by the interocular distance and head height, which were shorter than in fish not displaying pigmentary disorders. In addition to changes in the positioning of both eyes, pseudoalbino fish showed some ARA-induced osteological differences for some of the skeletal elements from the splanchnocranium (e.g. right premaxillary, dentary, angular, lacrimal, ceratohyal and branchiostegal rays) and neurocranium (e.g. sphenotic, left lateral ethmoid and left frontal) by comparison to normally pigmented specimens. Pseudoalbino fish also had teeth in both lower and upper jaws. This is the first study in Pleuronectiformes that describes impaired metamorphic relocation of the ocular side eye, the right eye in the case of S. senegalensis, whereas the left eye migrated into the ocular side almost normally.

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Environmental context. Headspace solid-phase microextraction (HS-SPME) and analysis by gas chromatography–mass spectrometry (GC/MS) system has been employed for quantifying the emissions of methyl chloride (CH3Cl) and methyl bromide (CH3Br) from plants and soils. Compared with more commonly used techniques, HS-SPME coupled to GC/MS is simple, fast, sensitive, economical and non-destructive, with potential for laboratory-based and field studies. Abstract. Headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC/MS) system have been employed for quantifying the emissions of methyl chloride (CH3Cl) and methyl bromide (CH3Br) from plants and soils. Seven SPME fibre coatings including 75 μm Carboxen-polydimethylsiloxane (CAR-PDMS), 85 μm Carboxen-PDMS (CAR-PDMS), 50/30 μm divinylbenzene-CAR-PDMS (DVB-CAR-PDMS), 65 μm DVB-PDMS, 65 μm carbowax-DVB (CW-DVB), 30 μm PDMS (PDMS) and 100 μm PDMS, were tested by comparing their sampling efficiencies towards CH3Cl and CH3Br. Key parameters such as extraction time, desorption temperature and time were all optimised in this work. The optimum conditions were found with CAR-PDMS 75 μm as an SPME fibre coating, a 1-min sampling time, a 50°C incubation temperature and a 2-min desorption time and a 250°C desorption temperature. These conditions were used for the determination of CH3Cl and CH3Br emission rates from different plant species as well as soil samples. Compared with more commonly used techniques, HS-SPME coupled to GC/MS is simple, fast, sensitive, economical and non-destructive, with potential for laboratory-based and field studies.