Sorption of arsenite, arsenate, and thioarsenates to iron oxides and iron sulfides: a kinetic and spectroscopic investigation.

Sorption to iron (Fe) minerals determines the fate of the toxic metalloid arsenic (As) in many subsurface environments. Recently, thiolated As species have been shown to dominate aqueous As speciation under a range of environmentally relevant conditions, thus highlighting the need for a quantitative understanding of their sorption behavior. We conducted batch experiments to measure the time-dependent sorption of two S-substituted arsenate species, mono- and tetrathioarsenate, and compared it to the sorption of arsenite and arsenate, in suspensions containing 2-line ferrihydrite, goethite, mackinawite, or pyrite. All four As species strongly sorbed to ferrihydrite. For the other sorbents, binding of the thiolated As species was generally lower compared to arsenate and arsenite, with the exception of the near instantaneous and complete sorption of monothioarsenate to pyrite. Analysis of the X-ray absorption spectroscopy (XAS) spectra of sorbed complexes implied that monothioarsenate binds to Fe oxides as a monodentate, inner-sphere complex. In the presence of Fe sulfides, mono- and tetrathioarsenate were both unstable and partially reduced to arsenite. Adsorption of the thiolated As species to the Fe sulfide minerals also caused the substitution of surface sulfur (S) atoms by As and the formation of As-Fe bonds.

Virological monitoring of white storks (Ciconia ciconia) for avian influenza.

Between 2003 and 2008, more than 600 white stork (Ciconia ciconia) nestlings in the German federal state of Brandenburg were ringed and examined for influenza A viruses. With the spread of highly pathogenic avian influenza virus (HPAIV) of subtype H5N1 among wild birds in Germany in spring 2006, dead wild birds, including 88 white storks, were tested for infection with HPAIV. Furthermore, fresh fecal samples were examined by RT-PCR to monitor the occurrence of HPAIV in adult storks. While the monitoring of nestlings and adult white storks failed to yield evidence of influenza A virus infections in these birds, two storks found dead in April 2006 in the same location tested positive for HPAIV H5N1. Sequence analysis revealed that the virus isolated from one of the storks belonged to clade 2.2, which was commonly found in wild birds in the north of Germany and other European countries during the epidemic in 2006. Despite these two cases, white storks seemed to serve as neither a vector nor as a reservoir for HPAIV in Germany. The risk of white storks transmitting HPAIV to domestic poultry and humans is low.

A virological survey in migrating waders and other waterfowl in one of the most important resting sites of Germany.

Wild birds are considered a potential reservoir or a carrier of viral diseases and may therefore play a role in the epidemiology of economically important or zoonotic diseases. In 2001 and 2002, a survey with special emphasis on virus isolation in migrating waders and some other birds were conducted. In one of the most important inland resting sites for migratory waterfowl, tracheal and cloacal swabs were collected from 465 waders representing 19 different species, and 165 other birds that were not captured on purpose. A total of 42 avian viruses were isolated, 34 of these were identified as paramyxoviruses (PMVs). The majority of isolates came from waders and wild ducks, and were characterized as PMV-1. In contrast, PMV-4 was found in wild ducks only, PMV-6 was mainly detected in wader species. Four avian influenza viruses (AIVs), belonging to H4 and H3 haemagglutinin subtype, were isolated from wild duck species. Furthermore, four reo-like viruses were isolated from one particular wader species for the first time. The majority of virus positive birds were <1 year old and did not show any clinical symptoms. There was no evidence for the presence of West Nile virus in these birds. These results confirm that the restricted resting sites in Western Europe must be considered as important locations for the intra- and interspecies transmission of avian viruses.