Methyl chloride emissions from halophyte leaf litter: dependence on temperature and chloride content

Methyl chloride (CH₃Cl) is the most abundant natural chlorine containing compound in the atmosphere, and responsible for a significant fraction of stratospheric ozone destruction. Understanding the global CH₃Cl budget is therefore of great importance. However, the strength of the individual sources and sinks is still uncertain. Leaf litter is a potentially important source of methyl chloride, but factors controlling the emissions are unclear. This study investigated CH₃Cl emissions from leaf litter of twelve halophyte species. The emissions were not due to biological activity, and emission rates varied between halophyte species up to two orders of magnitude. For all species, the CH₃Cl emission rates increased with temperature following the Arrhenius relation. Activation energies were similar for all investigated plant species, indicating that even though emissions vary largely between plant species, their response to changing temperatures is similar. The chloride and methoxyl group contents of the leaf litter samples were determined, but those parameters were not significantly correlated to the CH₃Cl emission rate.     

Untersuchungen zur Aufnahme von HCB und Pyren durch den KompostwurmEisenia fetida und ausgew?hlte Regenwurmwildarten

Zusammenfassung  Ziel der beschriebenen Untersuchungen war die praktische überprüfung eines Methodenentwurfs zur Erfassung der Bioakkumulation von Umweltchemikalien mitEisenia fetida, der Eignung vonE. fetida als Modellorganismus und des OECD-Kunstbodens als Standardsubstrat. Als Testorganismen wurden aus eigener Zucht der KompostwurmEisenia fetida und nach FeldentnahmeAllolobophora caliginosa, Allolobophora chlorotica, Allolobophora longa undLumbricus rubellus eingesetzt. Testb?den waren der OECD-Kunstboden und ein Boden vom Versuchsfeld der BBA in Berlin-Dahlem. Beiden B?den wurden die Testsubstanzen Hexachlorbenzol und Pyren in einer Konzentration von 10 mg/kg Bodentrockengewicht zugemischt. Die Expositionszeit der Regenwürmer betrug 4 Wochen bei w?chentlicher Bestimmung der Konzentrationen der Testsubstanzen in den Würmern und B?den. Die fürE. fetida sowie die Wildarten errechneten Anreicherungsfaktoren (AF) beliefen sich bei HCB in Abh?ngigkeit des verwendeten Bodens auf Werte zwischen 10 und 17 und bei Pyren auf Werte zwischen 0,9 und 1,7. Durch Umrechnung der Bodenkonzentrationen auf Gehalte in der Wasserphase und Ableitung der entsprechenden Anreicherungsfaktoren kann ein Vergleich mit BCF-Werten, die aus QSAR’S anderer Regenwurmarten und Fischen berechnet wurden, hergestellt werden. Die Ergebnisse lassen den Schluss zu, dass der Regenwurmtest mitE. fetida (OECD 1984, ISO 1998) für die Untersuchung der Bioakkumulation geeignet ist. OnlineFirst: 31. 05. 2002     

Virulence profiles of vancomycin-resistant enterococci isolated from surface and ground water utilized by humans in the North West Province,South Africa: a public health perspective

Environmental Science and Pollution Research - Vancomycin-resistant enterococci (VRE) have been responsible for numerous outbreaks of serious infections in humans worldwide. Enterococcus faecium...     

Simultaneous analysis of free and sulfo-conjugated steroid estrogens in artificial urine solution and agricultural soils by high-performance liquid chromatography

A simple and robust analytical method was developed to simultaneously detect and quantify 17β-estradiol (E2), estrone (E1), 17β-estradiol-3-sulphate (E2-3S), and estrone-3-sulphate (E1-3S) in aqueous solutions (calcium chloride and artificial urine solutions) and agricultural soils using high performance liquid chromatography and UV detection. The standards for all four compounds were linear in the range of 0.01 to 1.0 μg mL^?1 (n = 6) and 1.0 to 20 μg mL^?1 (n = 6), respectively, with correlation coefficients > 0.999. The on-column limits of detection at an injection volume of 50 μL and S/N (signal: noise) ratio of 3 were: 9.0 ng mL^?1, 10 ng mL^?1, 5.0 ng mL^?1, and 7.0 ng mL^?1 for E2-3S, E1-3S, E2 and E1, respectively. The limit of detection and quantification in artificial urine solution and CaCl₂ solution was 1.0 ng mL^?1 for all four compounds. Method detection limits for the compounds in the 3 soils ranged from 2 to 2.4 ng g^?1 (E2-3S and E1-3S), and 1.0 to 2.9 ng g^?1 (E2 and E1), respectively.     

Simultaneous analysis of free and sulfo-conjugated steroid estrogens in artificial urine solution and agricultural soils by high-performance liquid chromatography

A simple and robust analytical method was developed to simultaneously detect and quantify 17β-estradiol (E2), estrone (E1), 17β-estradiol-3-sulphate (E2-3S), and estrone-3-sulphate (E1-3S) in aqueous solutions (calcium chloride and artificial urine solutions) and agricultural soils using high performance liquid chromatography and UV detection. The standards for all four compounds were linear in the range of 0.01 to 1.0 μg mL(-1) (n = 6) and 1.0 to 20 μg mL(-1) (n = 6), respectively, with correlation coefficients > 0.999. The on-column limits of detection at an injection volume of 50 μL and S/N (signal: noise) ratio of 3 were: 9.0 ng mL(-1), 10 ng mL(-1), 5.0 ng mL(-1), and 7.0 ng mL(-1) for E2-3S, E1-3S, E2 and E1, respectively. The limit of detection and quantification in artificial urine solution and CaCl(2) solution was 1.0 ng mL(-1) for all four compounds. Method detection limits for the compounds in the 3 soils ranged from 2 to 2.4 ng g(-1) (E2-3S and E1-3S), and 1.0 to 2.9 ng g(-1) (E2 and E1), respectively.