Geochronology of anthropogenic radionuclides in Ribeira Bay sediments, Rio de Janeiro, Brazil

Ribeira Bay is located approximately 130 km south of the city of Rio de Janeiro and receives discharges of liquid effluent from the Angra dos Reis nuclear power plant (NPP) site, where two pressurized water reactors are located. To test whether the presence of anthropogenic radionuclides in sediments in Ribeira Bay could be correlated to the NPP operations, we sampled seven sediment cores and determined accumulation rates and chronologies. Only one sediment core did not exhibit a superficial mixing layer; this sample was used for dating purposes. Cesium-137 and ²⁰⁷Bi were observed in this sediment profile, but their presence was associated with atmospheric fall-out rather than the nearby NPP. The exponential decay of ²¹⁰Pb concentration with sediment layer depth was verified below a superficial mixing layer for all other sediment cores. Calculated accumulation rates ranged from 1.2 mm y⁻¹ in the inner bay to 6.2 mm y⁻¹ close to its entrance.     

Economic valuation of damages originated by major accidents in port areas

Due to special features of ports – variety of activities: storage and loading/unloading of hazardous materials; circulation of ships, lorries and trains; proximity to urban zones; etc. – major accidents can be associated with severe damages. The cost of such accidents must be known to allow for compensation to people and companies. A procedure is presented to estimate the cost of damages suffered by people, equipment and environment. Criteria to assess the cost of damage to people – a controversial issue – are discussed, establishing a method to predict the number of people killed, injured and evacuated. Economic compensation is proposed. Environmental damages are also considered. These include potential damage to the atmosphere, soil, water and fauna. Estimates of the cost of the equipment and buildings affected by the accident are proposed. Finally, an assessment of the loss of profits due to activity breakdown and indirect costs is analysed. The methodology presented can easily be extended to general, inland process and storage sites.     

Ozone oxidation and aerobic biodegradation with spent mushroom compost for detoxification and benzo(a)pyrene removal from contaminated soil

The combination of ozonation and spent mushroom compost (SMC)-mediated aerobic biological treatment was investigated in the removal of benzo(a)pyrene from contaminated soil. The performances of the process alone and combined were evaluated in terms of benzo(a)pyrene removal efficiency, mineralization efficiency (as total organic carbon removal), and soil residual toxicity (phytotoxicity to Lepidium Sativum and toxicity to Vibrio fischeri). In spite of the removal efficiency (35%) obtained by SMC-mediated biological process as a stand-alone treatment, the combined process showed a benzo(a)pyrene concentration reduction higher than 75%; the best removal (82%) was observed after 10 min pre-ozonation treatment. In particular, ozonation improved the biodegradability of the contaminant, as confirmed by the increase of CO(2) production (close to 70% compared to the control), mineralization (greater than 60%) and bacterial density (which increased by two orders of magnitude). Moreover, according to phytotoxicity tests on L. Sativum, the aerobic biological process of pre-ozonated soil decreased toxicity. According to the results achieved in the present study, ozonation pre-treatment showed an high potential to overcome the limitation of bioremediation of recalcitrant compound, but it should be carefully operated in order to maximize PAH removal efficiency as well as to minimize soil residual toxicity which can result from the formation of the oxidation intermediates.     

Plants as indicators of urban air pollution (ozone and trace elements) in Pisa, Italy

A biennial integrated survey, based on the use of vascular plants for the bioindication of the effects of tropospheric ozone, was performed in the area of Pisa (Tuscany, Central Italy). It also investigated the distribution of selected trace elements in plants and the data were compared with those obtained from the use of passive samplers, automatic analysers of ozone and lichen biodiversity. Photochemically produced ozone proved to be present during the warm season, with maximum hourly means surpassing 100 ppb: the use of supersensitive tobacco Bel-W3 confirmed the value of detailed, cost-effective, monitoring surveys. Trials with clover clones demonstrate that sensitive plants undergo severe biomass reduction in the current ozone regime. The mean NC-S (clover clone sensitive to ozone):NC-R (resistant) biomass ratio ranged from 0.7 (in 1999) to 0.5 (in 2000). The economic impact of these reductions deserves attention. The data obtained using passive ozone samplers exceeded those obtained using an automatic analyser. The mapping of epiphytic lichen biodiversity was not related to the geographical ozone distribution as can be seen from the tobacco's response. Lettuce plants grown under standardized conditions were used positively as bioaccumulators of trace elements: Pb was abundantly recovered, but a large portion of this element was removed by washing.     

Evaluation of cetacean exposure to organotin compounds in Brazilian waters through hepatic total tin concentrations

In Brazil, there is no restriction to the use of organotins (OTs). Previous investigations have shown that hepatic ∑Sn in cetaceans is predominantly organic. Hepatic ∑Sn concentrations were determined by GFAAS in 67 cetaceans (13 species) that stranded on Rio de Janeiro (RJ) and Espirito Santo (ES) states. Concentrations (in ng/g wet wt.) of marine tucuxis (n = 20) from the highly contaminated Guanabara Bay (in RJ) varied from 1703 to 9638. Concentrations of three marine tucuxi foetuses and one newborn calf (all from Guanabara Bay) varied between 431 and 2107. Contrastingly, the maximum level among 19 oceanic dolphins was 346, and 15 out of these 19 specimens presented concentrations below detection limit. The levels of Sn in six marine tucuxis from a less contaminated area (ES) varied from below detection limit to 744. Comparing to the literature, coastal cetaceans from Brazil appear to be highly exposed to OTs.     

Modelling of the migration of trace elements along groundwater flowpaths by using a steady state approach application to the site at El Berrocal (Spain)

The applications of geochemical modelling to natural water systems mostly rely upon the equilibrium assumption. This is in principle justified for deep groundwater systems with long water residence times.In addition, trace element behaviour in these natural systems has been normally modelled by taking into account the precipitation and dissolution of individual trace element phases.Recent geochemical modelling work related to natural analogue systems would indicate that: (1) the equilibrium condition is restricted to a limited number of components in long water residence times and (2) the behaviour of trace metals is very much connected to the major component cycling in the system.There is a need to develop our geochemical modelling capabilities to take these two facts into account in order to be able to predict the behaviour of trace components (radionuclides) in a geological repository.In this work we report on the successful application of steady-state kinetics in conjunction with co-dissolution/co-precipitation approaches to model trace element geochemistry in the natural analogue system at El Berrocal. The evolution of major components of the system (Ca (II), Al (III), CO₃²⁻ and Si) as well the trace elements investigated (U, Ba and Mn) is well reproduced by using the coupling between steady-state kinetics and co-dissolution/co-precipitation approaches.     

Modeling the influence of climate change on the mass balance of polychlorinated biphenyls in the Adriatic Sea

Climate forcing is forecasted to influence the Adriatic Sea region in a variety of ways, including increasing temperature, and affecting wind speeds, marine currents, precipitation and water salinity. The Adriatic Sea is intensively developed with agriculture, industry, and port activities that introduce pollutants to the environment. Here, we developed and applied a Level III fugacity model for the Adriatic Sea to estimate the current mass balance of polychlorinated biphenyls in the Sea, and to examine the effects of a climate change scenario on the distribution of these pollutants. The model’s performance was evaluated for three PCB congeners against measured concentrations in the region using environmental parameters estimated from the 20th century climate scenario described in the Special Report on Emission Scenarios (SRES) by the IPCC, and using Monte Carlo uncertainty analysis. We find that modeled fugacities of PCBs in air, water and sediment of the Adriatic are in good agreement with observations. The model indicates that PCBs in the Adriatic Sea are closely coupled with the atmosphere, which acts as a net source to the water column. We used model experiments to assess the influence of changes in temperature, wind speed, precipitation, marine currents, particulate organic carbon and air inflow concentrations forecast in the IPCC A1B climate change scenario on the mass balance of PCBs in the Sea. Assuming an identical PCBs’ emission profile (e.g. use pattern, treatment/disposal of stockpiles, mode of entry), modeled fugacities of PCBs in the Adriatic Sea under the A1B climate scenario are higher because higher temperatures reduce the fugacity capacity of air, water and sediments, and because diffusive sources to the air are stronger.     

Acid rain and nitrogen deposition in a sub-tropical watershed (Piracicaba): ecosystem consequences

High levels of wet N and acidic deposition were measured in southeast Brazil. In this study we addressed the sensitivity of water bodies and soils to acidification and N deposition in the Piracicaba River basin (12,400 km2). Average acid neutralization capacity (ANC) at 23 river sampling sites varied from 350 to 1800 microeq l(-1). Therefore, rivers and streams in the Piracicaba basin are well buffered, if the lower limit of 200 microeq l(-1) is assumed as an indication of poorly buffered waters. ANC is increased by untreated wastewaters discarded into rivers and streams of the region. Average NO3 concentrations varied from 20 to 70 microeq l(-1). At the most polluted river sites, NO3 concentration is not highest, however, probably due to NO3 reduction and denitrification. Most of the nitrogen in streams is also provided by wastewaters and not by wet deposition. The majority of the soils in the basin, however, are acidic with a low base cation content and high aluminum concentration. Therefore, soils in this basin are poorly buffered and, in areas of forest over sandy soils, acidification may be a problem.