Geochemical study of beachrocks and hybrid carbonates deposited during the Holocene in southeastern Brazil

The data refer to the geochemical and isotopic characterization of sandstones, with carbonate cementation (beach rocks), and hybrid carbonates, formed by algal mats, in the shallow platform of the South Atlantic Ocean, Espírito Santo - Brazil. The determination of 14C activity was performed on 10 samples in Accelerator Mass Spectrometry Dating (AMS), University of California, Irvine (UCL). Sample preparation backgrounds have been subtracted based on measurements of 14C-free calcite. Radiocarbon concentrations were given as fractions of the modern standard, δ14C, and the conventional radiocarbon age followed the convention of Stuiver and Polach (1977). The 14C calibration was performed on the Radiocarbon Calibration Program* CALIB REV7.1.0, Copyright 1986-2018 (Stuiver and Reimer, 1993), with marine13.14C calibration dataset (Reimer et al., 2013). The concentrations of rare earth elements (REEs) and traces were obtained by ICP-MS (PerkinElmer Nexlon300D), after digestion according to the modified EPA Protocol 3052. The quality of data was checked by the analysis of standard reference material (PACS-2 National Research Council, Canada)

Age determination of beachrocks and hybrid carbonates deposited during the Holocene in southeastern Brazil

The data refer to the geochemical and isotopic characterization of sandstones, with carbonate cementation (beach rocks), and hybrid carbonates, formed by algal mats, in the shallow platform of the South Atlantic Ocean, Espírito Santo - Brazil. The determination of 14C activity was performed on 10 samples in Accelerator Mass Spectrometry Dating (AMS), University of California, Irvine (UCL). Sample preparation backgrounds have been subtracted based on measurements of 14C-free calcite. Radiocarbon concentrations were given as fractions of the modern standard, δ14C, and the conventional radiocarbon age followed the convention of Stuiver and Polach (1977). The 14C calibration was performed on the Radiocarbon Calibration Program* CALIB REV7.1.0, Copyright 1986-2018 (Stuiver and Reimer, 1993), with marine13.14C calibration dataset (Reimer et al., 2013). The concentrations of rare earth elements (REEs) and traces were obtained by ICP-MS (PerkinElmer Nexlon300D), after digestion according to the modified EPA Protocol 3052. The quality of data was checked by the analysis of standard reference material (PACS-2 National Research Council, Canada)

Residential radon exposure and seasonal variation in the countryside of southeastern Brazil

Poorly ventilated environments such as residences can accumulate radon gas to levels that are harmful to humans and thus produce a public health risk. To assess the risk from natural radiation due to indoor radon exposure, 222Rn measurements, using an alpha RAD7 detector, were conducted in Timóteo, Minas Gerais state, southeastern Brazil. Indoor radon concentrations, along with meteorological parameters, were measured every 2 h during both wet and dry seasons in 2017 and 2018. The mean concentration of indoor radon varied between 18.0 and 412.8 Bq m−3, which corresponded to an effective annual dose of 1.2 and 7.6 mSv y−1. Average radon concentrations were significantly higher during the winter dry season, and there was a strong positive correlation with humidity in both wet and dry season. Furthermore, concentrations showed an inverse correlation with atmospheric pressure, wind speed, air temperature, and solar radiation. The radon levels are generally above the limits recommended by international standards, meaning that mitigation measures are needed to improve air quality to reduce human exposure and risk. Finally, through the statistical analysis, it was possible to determine the differences and similarities between the sampling points concerning the geology of the place and the geographical location

The use of caffeine as a chemical marker of domestic wastewater contamination in surface waters: seasonal and spatial variations in Teresópolis, Brazil

Abstract This study assessed the suitability of caffeine as an indicator for surface water pollution by domestic wastewaters. Caffeine concentrations determined in samples collected in the Paquequer River, located at the city of Teresópolis, a medium-sized city in the State of Rio de Janeiro, Brazil, were compared to other conventional water quality parameters such as phosphate, nitrate and ammonium concentrations to determine whether it as an efficient indicator of anthropic pollution of an urban aquatic environment. The Paquequer River originates in a pristine area called Parque Nacional da Serra dos Órgãos (PARNASO) and it crosses the urban area of the city of Teresópolis. Water samples were collected at seven points along the river, considering the periods of rain (summer) and drought (winter) and the different uses of land. Caffeine was measured using Solid Phase Extraction (SPE) and High Performance Liquid Chromatography (HPLC). Caffeine concentrations were found in a range from 0.16 to 47.5 µg L-1. The results show a positive relation between caffeine, phosphate, nitrate and ammonium concentrations and the increase of wastewater load, suggesting that caffeine can be used as an indicator of surface water pollution by domestic wastewaters

Effects of eutrophication and Typha domingensis Pers on methanogenesis in tropical constructed wetland

AIM: Constructed wetlands (CWs) have shown to be an efficient way for removing nutrients from wastewaters. However, a negative effect is the emission of greenhouse gases (GHGs). Methane (CH4) is a GHG released from the organic matter degradation under anaerobic conditions by methanogenic bacteria. In CWs, the excessive nutrient inputs may stimulate both primary production and methanogenesis and then affect the overall cost-benefit balance of this system. Here, we assessed the role of cattail stands (Typha domingensis Pers) on CH4 concentrations in eutrophic and mesotrophic constructed wetlands. METHODS: CWs were filled with water and sediment colonized by the aquatic macrophyte Typha domingensis Pers from two tropical freshwater lakes, one mesotrophic and another eutrophic. RESULTS: Our results showed consistently higher CH4 concentrations in waters and sediment in the eutrophic CWs than in the mesotrophic CWs (two times), indicating a positive influence of eutrophication on methanogenesis. CONCLUSION: In conclusion, CH4 emissions from tropical CWs demand to be considered or even mitigated in any use of this system

Mercury in freshwater, estuarine, and marine fishes from Southern Brazil and its ecological implication

In this study, we measured the mercury concentration in 27 different fish species with high commercial value. Samples were taken from a region characterized by the diversity of aquatic environments. Mercury concentration in marine fish species varied from 30.4 to 216 ng g−1, while in estuarine species, it varied from 12.4 to 60.3 ng g−1. Compared to mercury concentration in marine species, none of the specimens from estuarine environment has reached a mercury concentration of 100 ng g−1.However, mercury concentrations in species from the freshwater Patos lagoon are remarkably higher (15.3 to 462 ng g−1) than those from the estuarine or marine region. Even though mercury concentrations in these fish species did not exceed the maximum level (500 ng g−1) allowed by WHO for human consumption, they represent the main food source for sea birds and mammals coming from South Pole during their migration period