Geochemical transformation of soil cover and vegetation in a drained floodplain lake affected by long-term discharge of effluents from rayon industry plants,lower Don River Basin,Southern Russia

Environmental Geochemistry and Health - Lake Atamanskoye is one of the most polluted aquatic environments in the South of Russia. This water body was affected by long-term pollution by effluent...     

Electrolytic debromination of PBDEs in DE-83 technical decabromodiphenyl ether

Electrochemical debromination of the commercial decabromodiphenyl ether flame retardant DE-83 in partly aqueous tetrahydrofuran (THF) solution gave lower brominated congeners by sequential loss of bromine atoms. Hydrodebromination was most facile for the most heavily brominated congeners. It involves initial electron transfer and proton transfer from water, rather than hydrogen atom abstraction from THF, as shown by experiments with deuterated water. The product distribution from electrolysis involves preferential loss of bromine meta- and para- to the ether linkage, comparable with the products of metabolism of BDE-209 in various organisms. Significantly, the environmentally relevant congeners BDE-47, BDE-99, and BDE-154 were not major products of debromination of BDE-209 by the electron transfer mechanism.     

Catalytic and electrocatalytic hydrogenolysis of brominated diphenyl ethers

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental contaminants due to their use as additive flame-retardants. Conventional catalytic hydrogenolysis in methanol solution and electrocatalytic hydrogenolysis in aqueous methanol were examined as methods for debrominating mono- and di-bromodiphenyl ethers, as well as a commercial penta-PBDE mixture, in each case using palladium on alumina as the catalyst. Electrocatalytic hydrogenolysis employed a divided flow-through batch cell, with reticulated vitreous carbon cathodes and IrO2/Ti dimensionally stable anodes. Both methods gave efficient sequential debromination, with essentially complete removal of bromine from the PBDEs, but the electrocatalytic method was limited by the poor solubility of PBDEs in aqueous methanol.     

Is BDE-175 an important enough component of commercial octabromodiphenyl ether mixtures to be listed in Annex A of the Stockholm Convention?

Commercial octabromodiphenyl ether mixtures, containing hexabromodiphenyl ethers and heptabromodiphenyl ethers were listed in Annex A of the Stockholm Convention on May 2009 (Fourth Conference of the Parties) (UNEP, 2009a). Four compounds are specifically mentioned: 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE-153), 2,2′,4,4′,5,6′-hexabromodiphenyl ether (BDE-154), 2,2′,3,3′,4,5′,6-heptabromodiphenyl ether (BDE-175), and 2,2′,3,4,4′,5′,6-heptabromodiphenyl ether (BDE-183). Presumably they were identified as key components of commercial mixtures and found to be present in environmental samples. However, since BDE-175 and BDE-183 co-elute on common HRGC columns, the presence of BDE-175 as an important component in technical octa-BDE mixtures has not been illustrated. The successful HRGC/LRMS separation of a 1:1 mixture of BDE-175 and BDE-183, as well as ¹H NMR analysis of technical material, has allowed us to confirm that this congener is not present in technical products (e.g. Great Lakes DE-79™) in quantifiable amounts.     

Pollution status and human health risk assessment of potentially toxic elements and polycyclic aromatic hydrocarbons in urban street dust of Tyumen city,Russia

Environmental Geochemistry and Health - This study investigated levels and sources of pollution and potential health risks associated with potentially toxic elements (PTEs) and polycyclic aromatic...     

Characterization of mass-labeled [13C14]-decabromodiphenylethane and its use as a surrogate standard in the analysis of sewage sludge samples

Very little data is available about the presence of the brominated flame retardant, DBDPE, in the environment. This study reports the characterization of [(13)C(14)]-decabromodiphenylethane and the use of this surrogate standard to positively identify and quantify the presence of DBDPE in sewage sludge samples. The large difference in response factors between BDE-209 and DBDPE predicates the use of [(13)C(14)]-decabromodiphenylethane as a surrogate standard to improve the accuracy when determining the levels of DBDPE in environmental samples.     

Experience in establishing a natural standard for analyzing the dynamics of taiga ecosystems

Experience in organizing a natural reference area (standard) for studies on the functional dynamics of ecosystems in connection with paludification and forest-bog relationships is described. The essence of studies on ecosystem dynamics with the aid of natural standards and key plots is described using an example of the Yenisei region of Western Siberia. Arguments are presented for the necessity of using a differential approach to studies on the dynamics of nature and taking into account local ecological conditions while extrapolating the results of these studies to other geographic regions.     

Synthesis of the two minor isomers, delta- and epsilon-1,2,5,6,9,10-hexabromocyclododecane, present in commercial hexabromocyclododecane

Hexabromocyclododecane (HBCD) is prepared commercially by bromination of cis,trans,trans-cyclododecatriene (ctt-CDT) and widely used as a flame retardant, particularly in polystyrene foams. Commercial HBCD consists largely of three diastereomers, alpha-, beta-, and gamma-HBCD, the structures of which have been known for many years. Recently, the presence in the mixture of small amounts of two minor diastereomers, delta- and epsilon-HBCD, has been reported. Bearing in mind the manner in which commercial HBCD is generated, it was anticipated that these components are probably formed by bromination of trans,trans,trans-cyclododecatriene (ttt-CDT), a common contaminant in commercial ctt-CDT. Indeed, when a sample of ttt-CDT was brominated it gave two products, the NMR spectra and LC/MS and GC/MS behaviour of which confirmed that they are identical to the minor components, delta- and epsilon-HBCD, present in commercial HBCD.     

PLATE JUNCTIONS AND HYDROCARBON ACCUMULATIONS IN THE INDIAN REGION

This article relates the productive and potential oil fields in India to plate junctions and other major tectonic features. High geothermal gradients are known to accelerate the expulsion of petroleum from the source bed, as well as its migration and accumulation in favourable reservoir rocks, resulting in high yield. Some of the world's major petroleum deposits occur along ‘failed arms’ associated with the plume generated triple junctions. Seven triple junctions have been located in the Indian region, and two more are identified here. Interestingly, India's off-shore petroleum prospects coincide with some of these triple junctions. Cet article établit la relation entre les champs de pétrole en production et potentiels en Inde à la théorie des plaques et à d'autres traits tectoniques importants. L'on sait que des gradients géothermiques élevés accélèrent l'expulsion du pétrole à partir de la roche-mère et favorisent la migration et l'accumulation dans des réservoirs convenables. Quelques-uns des plus grands champs de pétrole du monde se rencontrent en liaison avec des ‘bras morts’ associés avec un système triple de fossés d'effondrement. Sept systèmes triples ont été repérés en Inde et deux autres sont reconnus ici. II est intéressant de remarquer que les possibilités pétrolières de l'offshore indien coïncide avec certains de ces systèmes triples. Este artículo establece la relación entre los campos petrolíferos en producción y potenciales de India a la teoría de placas y otros aspectos tectónicos. Es sabido que una gradiente térmica alta ascelera la expulsión del petróleo desde la roca madre y favorece su migración y acumulación en rocas reservorio favorables. Algunos de los mayores depósitos de petróleo se encuentran a lo largo de los “brazos muertos” asociados a un sistema triple de unión de placas. Siete uniones de este tipo habia sido localizadas en India y otros dos más son identificados aquí. Es interesante notar que las posibilidades petroleras en la zona marítima de India coinciden con alguna forma de sistemas triple de placas.     

Effect of Ecological Factors on the Accumulation of Fluorine by Larches, <Emphasis Type="Italic">Larix gmelinii</Emphasis> (Rupr.) Rupr. and <Emphasis Type="Italic">L. sibirica</Emphasis> Ledeb., in Eastern Siberia

The accumulation of fluorine in the trunk wood and branches of Larix gmelinii growing on soils with a naturally increased fluoride content and of L. sibirica growing in a zone affected by atmospheric emissions from an aluminum plant has been studied. Based on results of in vivo and in vitro experiments, it is concluded that larch trees manifest individual differences in their response to fluorine.