C, δC and total C content in soils around a Brazilian PWR nuclear power plant

Nuclear power plants release ¹⁴C during routine operation mainly as airborne gaseous effluents. Because of the long half-life (5730 years) and biological importance of this radionuclide (it is incorporated in plant tissue by photosynthesis), several countries have monitoring programs in order to quantify and control these emissions. This paper compares the activity of ¹⁴C in soils taken within 1 km from a Brazilian nuclear power plant with soils taken within a reference area located 50 km away from the reactor site. Analyses of total carbon, δ¹³C and ¹³⁷Cs were also performed in order to understand the local soil dynamics. Except for one of the profiles, the isotopic composition of soil organic carbon reflected the actual forest vegetation present in both areas. The ¹³⁷Cs data show that the soils from the base of hills are probably allocthonous.     

Genotoxic effects of binary mixtures of xenoandrogens (tributyltin, triphenyltin) and a xenoestrogen (ethinylestradiol) in a partial life-cycle test with Zebrafish (Danio rerio)

A partial life-cycle test with the model fish Danio rerio was performed in order to evaluate the genotoxic potential of binary mixtures of xenoandrogenic (tributyltin--TBT; triphenyltin--TPT) and an estrogenic compound (ethinylestradiol--EE2). Five days post-fertilisation larvae were diet-exposed to environmental relevant concentrations of TBT and TPT (25 ng/g-100 ng/g), and water-exposed to ethinylestradiol (3.5 ng/L) for a four-month period; binary mixtures of TBT plus EE2 and TPT plus EE2 were run in parallel. The erythrocytic nuclear abnormalities (ENA) assay in circulating erythrocytes was used to evaluate genotoxicity in the end of the four-month exposure period. A significant increase (p<0.05, Kruskall-Wallis non-parametric ANOVA) in ENA frequency, in comparison with control animals, was observed in those animals exposed to TBT and TPT (the highest doses only), and to EE2 and the binary mixtures, although neither synergistic nor additive effects of the tested compounds were evident. Overall, the results clearly indicate that chronic exposure to low levels of TBT, TPT, EE2 and binary mixtures of TBT plus EE2 and TPT plus EE2 are genotoxic to zebrafish, which may suggest that wild fish populations may be under increased DNA damage in areas contaminated by these endocrine disrupting chemicals.     

The unpredictable effects of mixtures of androgenic and estrogenic chemicals on fish early life

Estuarine shallow areas and coastal lagoons are known to receive and concentrate multiple inputs, either from land, rivers or coastal areas, being intensively impacted by chemical contamination, namely endocrine disrupting chemicals (EDCs). Despite the ubiquitous coexistence of several classes of EDCs in most of these aquatic ecosystems, there is still limited information regarding their combined effects. Furthermore, given the immediate implications for population dynamics, the available laboratory studies almost invariably focus on very specific life history stages, such as embryonic development or reproduction, thus creating a gap on our knowledge of what happens in between. During this 'intermediate phase', the newborn larvae and juveniles face numerous challenges whose outcome may impair reproduction or even survival. The black-striped pipefish, Syngnathus abaster, member of the Syngnathidae family (comprising pipefish, seahorses and seadragons), usually breeds in coastal areas such as estuaries, where its newborns are immediately exposed to EDCs. Given the ongoing decline of pipefish populations, together with the observed shrinkage and fragmentation of seagrass meadows, known to be impacted by EDCs, a first reasonable question to address is if pipefish newborns respond to environmentally relevant concentrations of ubiquitous EDCs, either single or in combination. Hence, a seven days exposure experiment to the estrogenic chemical ethinylestradiol (EE(2)) and the androgenic chemical tributyltin (TBT), single and in binary mixtures, was conducted. Selected behavioural (e.g. predator avoidance) and developmental variables (e.g. growth) were monitored in pipefish juveniles after EDCs insult. The obtained results indicate that EE(2), TBT, or their combined exposure, do impact pipefish early life. However, the pattern of results emerging from the measured variables clearly indicates that mixtures significantly modulate newborn responses in distinct ways when compared to individual chemical's exposure. These findings further demonstrate the importance of addressing the issue of chemical mixtures of pollutants acting through dissimilar mode of action. Independently of all the observed response variations, an ultimate conclusion seems certain: EE(2) and TBT, single or in combination, induce disruption patterns able to imbalance pipefish survival. Since these (as well as other) contaminants are present in estuarine areas, profound implications in population structure could be expected, ranging from a decrease in recruitment to a disruption of sexual selection. Inexorably, these stressors simultaneously operate in already declining populations.     

Impact of climate warming upon the fish assemblages of the Portuguese coast under different scenarios

Impact of sea-surface warming upon the fish assemblages of the Portuguese coast was assessed under two scenarios, the A2 and the B2 scenarios (Special Report on Emission Scenarios), which when coupled with a regional circulation model HadRM3 predict 1 and 2°C of sea-surface warming until the year 2100. Species richness increased in the Portuguese coast. In both scenarios, there was a latitudinal gradient in the amount of lost and gained species, increasing from north to south. An anomaly in the latitudinal gradient of species richness was detected in the southernmost area, which presented the lowest species richness of all areas, in the A2 scenario, and appears to be particularly vulnerable to climate change. Very few species were totally eliminated from Portuguese waters. For the Portuguese coast as a whole, there were more new than lost species, in both scenarios. Most of the new species were commercially important species, in the majority subtropical in the north and tropical in the south, mainly demersal and reef-associated. Reef-associated species also increased in relative importance. A commercial opportunity for fisheries may arise from climate warming, since most of the new species were commercial species and not many commercial species were lost. An increasing gradient from north to south was detected in the colonization of new species of herbivores, planktivores, and omnivores, as well as lower mean trophic level, which might have consequences for the future of trophic webs.     

Tourists‘ and Locals‘ Preferences Toward Ecotourism Development in the Maya Biosphere Reserve,Guatemala

Ecotourism has been identified as a low impact means to provide income generating opportunities that are complementary to nature conservation as well as the welfare of the local population. The Maya Biosphere Reserve in Peten, Guatemala is one of Central America's largest and most isolated protected areas. And although the area is contains a well-visited archeological site, it has not been developed for ecotourism. In this study choice experiments are used to analyze the preferences toward alternative scenarios of ecotourism of two important stakeholder groups: foreign tourists and educated local residents. Results demonstrate that these two populations of have unequal but similar preference orderings, especially toward: improved national park management and the presence of guides for wildlife viewing. These stakeholder groups had different opinions toward paved access roads and the presence of illegal colonists within the protected area. Both populations favored an entrance fee toward the absence of an entrance fee. These preferences were generally consistent across other socioeconomic indicators. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Extent of sonochemical degradation and change of toxicity of a pharmaceutical precursor (triphenylphosphine oxide) in water as a function of treatment conditions

The degradation of triphenylphosphine oxide (TPPO) in water, a toxic compound typically found in effluents from the pharmaceutical industry, by means of ultrasonic irradiation at 20 kHz has been investigated with emphasis on the effect of various parameters on conversion and acute toxicity. Experiments were carried out at liquid volumes of 50 and 80 ml, electric power outputs of 125, 187.5 and 250 W, initial TPPO concentrations of 10, 100 and 350 mg/L and temperatures of 5, 20, 35, 50 and 70 degrees C. TPPO conversion was found to increase with increasing power output and decreasing initial concentration and temperature. Measurements of dissolved total carbon showed that liquid-phase degradation by-products were more stable to ultrasonic irradiation than TPPO. Addition of t-butanol as a radical scavenger at a concentration of 1000 mg/L nearly completely suppressed TPPO degradation. Conversely, addition of radical promoters (Fe(2+) ions or H(2)O(2)) had a positive effect on degradation. Acute toxicity to marine bacteria vibrio fischeri was measured before and after ultrasonic irradiation. At the conditions employed in this study, irradiated TPPO samples were always more toxic than TPPO itself with toxicity levels being a function of treatment conditions.     

Intake of uranium and radium-226 due to food crops consumption in the phosphate region of Pernambuco--Brazil

The phosphate region located in the Northeast of Brazil covers an area of approximately 150 km long with an average width of 4 km, along the coast of the states of Pernambuco and Paraíba. The inhabitants of this area are exposed to natural radioactivity levels higher than the background values recorded in the literature, mainly due to the presence of uranium and its decay products in the phosphatic sediments. The main aim of this study was to determine the activity concentration of uranium and (226)Ra in foodstuffs cultivated in this area, where the phosphate mineral has been extracted. The activity concentrations found for uranium and (226)Ra in the foodstuffs analyzed varied from 13 to 186 mBq kg(-1) (wet weight), with a mean value of 46 mBq kg(-1) and from 43 to 2209 mBq kg(-1) (wet weight), with a mean value of 358 mBq kg(-1), respectively. The annual intake of these radionuclides, for rural residents, was 7.45 Bq for uranium and 69.3 Bq for (226)Ra.     

Contrasting impacts of climate change across seasons: effects on flatfish cohorts

The Senegal sole, Solea senegalensis, is a species of flatfish that has several distinct cohorts of 0-group juveniles which use estuarine nurseries in summer and winter. The early cohort is more abundant and grows faster than the late cohort that stays in the nurseries during winter; however, climate warming may have an impact on the dynamics of this species’ juveniles. This study aimed to compare mortality, metabolic response and growth of S. senegalensis juveniles at different temperatures, reflecting present-day temperature (winter—12 °C; summer—24 °C) and future temperature (plus 3 °C) conditions, in estuarine nurseries in the southern European population. Mortality was low at 12 °C, being only 10 %, increasing to 30 % at 15 °C, 40 % at 24 °C and at 27 °C it hit 70 %. Metabolic rate increased steadily with increasing temperatures, yet it increased steeply from 24 to 27 °C. Thermal sensitivity was high for the temperature interval between 24 and 27 °C. Growth was very slow at 12 °C, at a rate of 0.03 mm day^?1, increasing to 0.22 mm day^?1 at 15 °C, and to 0.60 mm day^?1, at 24 °C. However, at 27 °C growth rapidly declined to 0.12 mm day^?1. Warming will be beneficial for the late cohort, resulting in a major increase in growth. However, the early cohort will not benefit from warming, due to high mortality and arrested growth, which clearly indicates that this species is under severe thermal stress at 27 °C. Thus, here we show, for the first time, that climate change may induce contrasting seasonal impacts on fish bio-ecology and physiology, namely in species with several cohorts over the course of the year. Phenotypic and/or genotypic plasticity may limit the impacts of climate change.     

Recent Cs deposition in sediments of Admiralty Bay, Antarctica

Cesium-137, radium-226 and lead-210 profiles of a 25 cm sediment core give an indication of recent changes in land-ocean interactions at a polar coastal environment (Admiralty Bay, King George Island, Antarctica). The linear sedimentation accumulation rate at the study site calculated from the unsupported ²¹⁰Pb profile was 6.7 mm/year from 1965 to 2005. A 3.5-fold increase in ¹³⁷Cs concentrations was observed in the top layer of this sediment core. This sharp increase seems to indicate a recent redistribution of fallout radionuclides previously deposited on soil, vegetation and snow. These results imply enhanced land-ocean interactions at this site likely as a result of climate change. Because our results are based on a single core, additional investigations are needed to confirm our observations.     

210Po concentration in Perna perna mussels: looking for radiation effects

Twenty ropes with 400 Perna perna mussels seeds (3 cm shell size) were set-up on floating structures at Cabo Frio Island, Arraial do Cabo, approximately 100 km northeast of Rio de Janeiro city. A rope was taken out on a monthly basis, and the shell sizes of 100 seeds were measured. The haemolymph of 10 male and 10 female individuals was taken, and the same individuals were separated for 210Po/210Pb determination. After one year of monthly sampling, no clear correlation was observed between the 210Po concentration, mussel's age and weight. A mean 210Po concentration of 155 Bq kg(-1) wet weight basis, was obtained, which is comparable with data reported in the literature. The radiation dose did not have any observable effect on the micronuclei frequency and DNA breaks in the mussels. This was probably due to the low dose rate, 0.02 mGy d(-1), in comparison with the suggested potential dose limit of 10 mGy d(-1).