Bioindication of volatile elements emission by the Puyehue-Cordón Caulle (North Patagonia) volcanic event in 2011

The emission of volatile pollutants from the volcanic eruption of the Puyehue-Cordón Caulle complex (North Patagonia Andean Range) that started in June 4th, 2011, was investigated by bioindication means with the epyphytic fruticose lichen Usnea sp. The elemental composition of pooled samples made up with 10 lichen thalli were analysed by Instrumental Neutron Activation Analysis. Eleven sampling sites were selected within the impacted region at different distance from the volcanic source. Five sites were selected as they were already sampled in a previous study prior to the eruption. Two other new sampling sites were selected from outside the impacted zone to provide non-impacted baseline sites.The elements associated with the lichen incorporation of particulate matter (PM) of geological origin were identified by linear correlation with a geochemical tracer (Sm concentrations). The elements associated with PM uptake were Ce, Eu, Fe, Hf, La, Lu, Na, Nd, Sb, Sc, Se, Ta, Tb, Th, U, and Yb. Arsenic and Cs concentrations showed contributions exceeding the PM fraction in sites near the volcanic centre, also higher than the baseline concentrations, which could be associated with permanent emissions from the geothermal system of the Puyehue-Cordón Caulle complex. The lichen concentrations of Ba, Ca, Co, Hg, K, Rb, Sr, and Zn were not associated with the PM, not showing higher concentrations in the sites nearby the volcanic source or respect to the baseline values either. Therefore, there is no indication of the emission of volatile forms of these elements in the lichen records. The lichen records only identified Br volatile emissions associated with the Puyehue-Cordón Caulle complex eruption in 2011.     

Methylmercury and total mercury in estuarine organisms from Rio de Janeiro, Brazil

Guanabara Bay (GB), located in the Rio de Janeiro State, is still a productive estuary on the south-eastern Brazilian coast. It is an ecosystem heavily impacted by organic matter, oil and a number of other toxic compounds, including Hg. The present study aimed to comparatively evaluate the aquatic total mercury (THg) and MeHg contamination, and the ratios of MeHg to THg (% MeHg), in 3 species of marine organisms, Micropogonias furnieri-carnivorous fish (N = 81), Mugil spp.--detritivorous fish (N = 20) and Perna perna--filter-feeding bivalves (N = 190), which are widely consumed by the population. A total of 291 specimens were collected at the bay in different periods between 1988 and 1998. THg concentrations were determined by cold vapour AAS with stannous chloride as a reducing agent. MeHg was extracted by dithizone-benzene and measured by GC-ECD. Analytical quality was checked through certified standards. All organisms presented both low THg and MeHg concentrations and they were below the maximum limit of 1,000 micrograms Hg.kg-1 wet wt. as established for human intake of predatory fish by the new Brazilian legislation. Carnivorous fish showed higher THg and MeHg concentrations, and also % MeHg in muscle tissues, than organisms with other feeding habits and lower trophic levels. The average of THg concentrations in carnivorous fish was 108.9 +/- 58.6 micrograms.kg-1 wet wt. (N = 61) in 1990 and 199.5 +/- 116.2 micrograms.kg-1 wet wt. (N = 20) in 1998, but they presented different total length and body weights. The average THg content in detritivorous fish was 15.4 +/- 5.8 micrograms.kg-1 wet wt., whereas THg concentrations ranged from 4.1 to 53.5 micrograms.kg-1 wet wt. for the molluscs. The THg and MeHg contents of mussel varied according to the sampling point and water quality. MeHg concentration in detritivorous fish was similar to MeHg concentration in molluscs, but there was a significant difference in the MeHg/THg ratio: the carnivorous fish presented higher MeHg percentages (98%) than the detritivorous fish (54%) and the molluscs (33%). Weight-normalised average concentration of THg in carnivorous fish collected in 1990 (0.18 +/- 0.08 microgram.g-1/0.7 kg wet wt.) and in 1998 (0.16 +/- 0.09 microgram.g-1/0.7 kg wet wt.) presented no significant difference (t = 1.34; P < 0.5). In conclusion, the low THg and MeHg concentrations in the organisms from the GB ecosystem, are related to its eutrophic conditions and elevated amounts of suspended matter. In this situation, Hg could be strongly complexed or adsorbed by the particulate, which would dilute the Hg inputs and reduce its residence time in the water column, with a consequent decrease in its availability to organisms.     

Bioaccumulation of anthropogenic contaminants by detritivorous fish in the Río de la Plata estuary: 1-aliphatic hydrocarbons

The temporal variability and bioaccumulation dynamics of C_12–25 n-alkanes, isoprenoids and unresolved aliphatic hydrocarbons (UCM) were studied in a detritivorous fish (Sábalo: Prochilodus lineatus) collected from 1999 to 2005 in the sewage impacted Buenos Aires coastal area. Fish muscles contain huge amounts of n-C_12–25 (165 ± 93, 70 ± 48 or 280 ± 134 μg g⁻¹, dry, fresh and lipid weight, respectively) and UCM (931 ± 560, 399 ± 288 and 1567 ± 802 μg g⁻¹) reflecting the chronic bioaccumulation of fossil fuels from sewage particulates. On a temporal basis, lipid normalized aliphatic concentrations peaked by the end of 2001–2002 during the rainiest period over the last four decades (1750 vs. 1083 ± 4.6 mm in 1999, 2004 and 2005), reflecting an enhanced exposition due to massive anthropogenic fluxes from Metropolitan Buenos Aires in wet years. The hydrocarbon composition in fish muscles is enriched in n-C_15–17 and isoprenoids relative to a fresh crude oil and settling particulates, with fresher signatures during the 2001–2002 maxima. Fish/settling material bioaccumulation factors (BAFs: 0.4–6.4 dry weight or 0.07–0.94 lipid-organic carbon) plotted against K_ow showed a parabolic pattern maximizing at n-C_14–18 and isoprenoids. The optimal bioaccumulation window corresponds to highly hydrophobic (log K_ow: 7.2–9.9), intermediate-size C_14–18 n-alkanes and C_15–20 isoprenoids (MW: 198–282; length: 17.9 to 25.4 Å) with melting points ranging from −19.8 to 28 °C. The uptake efficiency is inversely correlated to melting points and increased from 75% for n-C₂₅ to above 90% for n-C_14–15 and isoprenoids.     

Preliminary indoor radon risk assessment at the Poços de Caldas Plateau,MG-Brazil

This paper aims to present an assessment of the environmental radiological exposure at a Brazilian area of high natural radiation and discusses the indoor radon exposure risk. A survey of inhabitant exposures arising from the inhalation of radon progeny and external gamma exposure was conducted in urban and rural areas of the Po?os de Caldas Plateau, which is recognized worldwide as a high natural radiation region. The results of this survey indicated that highest radiation exposure was restricted to the rural area of Po?os de Caldas. The radiation exposure in urban locations was quite similar to the values observed in normal background areas in some Brazilian counties. By the application of a constant relative risk model, an additional 20% in the lifetime risk of lung cancer mortality due to the exposure to radon progeny was estimated at Po?os de Caldas. It was also estimated that 16% of all lung cancer deaths at Po?os de Caldas county could be attributable to radon exposure.