Polycyclic aromatic hydrocarbons. A review

Polycyclic aromatic hydrocarbon (PAH) diagnostic ratios have recently come into common use as a tool for identifying and assessing pollution emission sources. Some diagnostic ratios are based on parent PAHs, others on the proportions of alkyl-substituted to non-substituted molecules. The ratios are applicable to PAHs determined in different environmental media: air (gas + particle phase), water, sediment, soil, as well as biomonitor organisms such as leaves or coniferous needles, and mussels. These ratios distinguish PAH pollution originating from petroleum products, petroleum combustion and biomass or coal burning. The compounds involved in each ratio have the same molar mass, so it is assumed they have similar physicochemical properties. Numerous studies show that diagnostic ratios change in value to different extents during phase transfers and environmental degradation. The paper reviews applications of diagnostic ratios, comments on their use and specifies their limitations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Phylogenetic analyses of 16S rRNA gene sequences by distance matrix and parsimony methods indicated that the currently known species of the genus Sphingomonas can be divided into four clusters. Some chemotaxonomic and phenotypic differences were noted among these clusters. Three new genera, Sphingobium, Novosphingobium and Sphingopyxis, are proposed in addition to the genus Sphingomonas sensu stricto. The genus Sphingobium is proposed to accommodate Sphingomonas chlorophenolica, Sphingomonas herbicidovorans and Sphingomonas yanoikuyae. The genus Novosphingobium is proposed for Sphingomonas aromaticivorans, Sphingomonas capsulata, Sphingomonas rosa, Sphingomonas stygia, Sphingomonas subarctica and Sphingomonas subterranea. Sphingomonas macrogoltabidus and Sphingomonas terrae are reclassified in the genus Sphingopyxis. The type species of Sphingobium, Novosphingobium and Sphingopyxis are Sphingobium yanoikuyae, Novosphingobium capsulatum and Sphingopyxis macrogoltabida, respectively.