Fate of antimony contamination generated by road traffic - A focus on Sb geochemistry and speciation in stormwater ponds

Although antimony (Sb) contamination has been documented in urban areas, knowledge gaps remain concerning the contributions of the different sources to the Sb urban biogeochemical cycle, including non-exhaust road traffic emissions, urban materials leaching/erosion and waste incineration. Additionally, details are lacking about Sb chemical forms involved in urban soils, sediments and water bodies. Here, with the aim to document the fate of metallic contaminants emitted through non-exhaust traffic emissions in urban aquatic systems, we studied trace element contamination, with a particular focus on Sb geochemistry, in three highway stormwater pond systems, standing as models of surface environments receiving road-water runoff. In all systems, differentiated on the basis of lead isotopic signatures, Sb shows the higher enrichment factor with respect to the geochemical background, up to 130, compared to other traffic-related inorganic contaminants (Co, Cr, Ni, Cu, Zn, Cd, Pb). Measurements of Sb isotopic composition (δ¹²³Sb) performed on solid samples, including air-exposed dusts and underwater sediments, show an average signature of 0.07 ± 0.05‰ (n = 25, all sites), close to the δ¹²³Sb value measured previously in certified reference material of road dust (BCR 723, δ¹²³Sb = 0.03 ± 0.05‰). Moreover, a fractionation of Sb isotopes is observed between solid and dissolved phases in one sample, which might result from Sb (bio)reduction and/or adsorption processes. SEM-EDXS investigations show the presence of discrete submicrometric particles concentrating Sb in all the systems, interpreted as friction residues of Sb-containing brake pads. Sb solid speciation determined by linear combination fitting of X-Ray Absorption Near Edge Structure (XANES) spectra at the Sb K-edge shows an important spatial variability in the ponds, with Sb chemical forms likely driven by local redox conditions: "dry" samples exposed to air exhibited contributions from Sb(V)-O (52% to 100%) and Sb(III)-O (<10% to 48%) species whereas only underwater samples, representative of suboxic/anoxic conditions, showed an additional contribution from Sb(III)-S (41% to 80%) species. Altogether, these results confirm the traffic emission as a specific source of Sb emission in surface environments. The spatial variations of Sb speciation observed along the road-to-pond continuum likely reflect a high geochemical reactivity, which could have important implications on Sb transfer properties in (sub)surface hydrosystems.

Precipitation of greigite and pyrite induced by Thermococcales: an advantage to live in Fe- and S-rich environments?

Thermococcales, a major order of archaea inhabiting the iron- and sulfur-rich anaerobic parts of hydrothermal deep-sea vents, have been shown to rapidly produce abundant quantities of pyrite FeS₂ in iron-sulfur-rich fluids at 85°C, suggesting that they may contribute to the formation of 'low temperature' FeS₂ in their ecosystem. We show that this process operates in Thermococcus kodakarensis only when zero-valent sulfur is directly available as intracellular sulfur vesicles. Whether in the presence or absence of zero-valent sulfur, significant amounts of Fe₃ S₄ greigite nanocrystals are formed extracellularly. We also show that mineralization of iron sulfides induces massive cell mortality but that concomitantly with the formation of greigite and/or pyrite, a new generation of cells can grow. This phenomenon is observed for Fe concentrations of 5 mM but not higher suggesting that above a threshold in the iron pulse all cells are lysed. We hypothesize that iron sulfides precipitation on former cell materials might induce the release of nutrients in the mineralization medium further used by a fraction of surviving non-mineralized cells allowing production of new alive cells. This suggests that biologically induced mineralization of iron-sulfides could be part of a survival strategy employed by Thermococcales to cope with mineralizing high-temperature hydrothermal environments.

HE BURDEN AND CHALLENGES OF NEONATAL TETANUS IN KILIFI DISTRICT, KENYA--2004-7

OBJECTIVES

To describe the incidence of neonatal tetanus (NNT) and to describe the trends between 2004 and 2007; to show the geographical distribution of NNT in Kilifi district and to describe routine immunisation coverage, catch-up campaigns and mop-ups.

DESIGN

Retrospective study

SETTING

Kilifi district, Coastal Kenya

SUBJECTS

Children diagnosed with Neonatal Tetanus (NNT) attending Health facilities in the District.

RESULTS

The incidence of NNT in Kilifi increased from 0.6 in 2004 to 1.0 per 1000 live births in 2007. Over 50% of Kilifi district was a high risk area for NNT. It was a public health problem (> 1 per 1000 live births) in 19/36 locations. Immunisation (TT2+) increased from 4% in 2004 to 17% in 2007 for women of childbearing age and from 22% to 98% for pregnant women in the same period. All cases of NNT were delivered at home. 83% of NNT cases had potentially infectious materials applied to their cords.

CONCLUSIONS

Neonatal tetanus was an increasing problem in Kilifi district in the period 2004-2007. Immunisation coverage was low for women of childbearing age. TT immunisation data capture was a mix-up (pregnant women andwomen of childbearing age) at various health facilities and was a challenge to accurate estimates of TT2+ immunisation coverage.

Diarrheal morbidity and mortality in children in the Central African Republic

Diarrheal morbidity and mortality in children less than 5 years old were studied in Bangui, Central African Republic, by a cluster survey. We found a high prevalence of diarrheal disease with an estimated annual incidence of 7 episodes of diarrhea per child per year. The estimated annual mortality rate for children less than 5 years old was 28.6 per 1,000 and 85.8 per 1,000 for infants; 51.6% of deaths were reported to be associated with diarrhea. During the survey, stool specimens were collected from 133 children with current diarrhea and 117 control children to study the etiologic agents of diarrheal disease in the community. An enteric pathogen was identified in 58% of diarrheal children's stools and 48% of stools of well children. A statistically significant association between diarrhea and rotavirus was found, with it being isolated from 8 of 33 (24%) of stools of infants with diarrhea compared to 0 of 25 (0%) of control infants. Isolation rates for Campylobacter jejuni, Entamoeba histolytica, pathogenic Escherichia coli, and other bacterial enteropathogens did not differ significantly between children with diarrhea and control children.

Distribution and serotypes of Campylobacter jejuni and Campylobacter coli in enteric Campylobacter strains isolated from children in the Central African Republic

One hundred eighty-five enteric Campylobacter strains isolated from diarrheic or healthy children in Bangui (Central African Republic) were studied to determine their species and serotypes. C. coli was identified in 38.9% of all strains and in 43.9% of strains from diarrheic children. By the hemagglutination technique for heat-stable antigens, 73.5% of the strains could be serotyped. Of the typeable strains, 75% were distributed among 13 more frequent serotypes. C. coli serotype Pen 37,56 was the most common serotype from diarrheic children.

[Serotypes, lysotypes and antibiotypes of 127 strains of Salmonella isolated in the Central African Republic: evaluation of 3378 samples taken in Bangui]

The authors have tested for Salmonella in 3,378 samples collected over a period of 17 months in the Central African Republic. They have isolated 127 strains of Salmonella (S. typhi not included). These Salmonella are distributed according to 41 serotypes, one of which is new. They have tested the sensitivity of all the isolated strains to different antibiotics and they have noted that the 5 animal strains and 5.7% of the human strains were resistant to chloramphenicol. They discuss the epidemiological importance of these facts.

[The role of rotaviruses in the etiology of infantile diarrhea in the Central African Republic]

The stools of 1 138 diarrheic children and 298 controls have been investigated for rotavirus during the course of 1982. The results were positive for 21.9% of the patients and 6.7% of the controls. The maxima incidence of rotavirus has been found among children from new born to 11 months old and during the dry season. The results are compared with those of other authors.