Cytotoxic and genotoxic evaluation and chemical characterization of sewage treated using activated sludge and a floating emergent-macrophyte filter in a municipal wastewater treatment plant: a case study in Southern Brazil

This study was conducted to evaluate the chemical parameters and the cytotoxic and genotoxic potential of raw domestic sewage and effluents from treatment with activated sludge and a floating emergent-macrophyte filter from a domestic wastewater treatment plant in the city of Novo Hamburgo, Rio Grande do Sul, Brazil. The physicochemical analysis revealed that both treatment systems achieved the legal emission pattern for biochemical oxygen demand, chemical oxygen demand, and suspended solids, but ammoniacal nitrogen and E. coli values were above the limits in the macrophyte treatment effluent. Phosphorous values were above the maximum permitted for both treatments. The results obtained from the Allium cepa test and the micronuclei test in fish did not demonstrate any significant differences in both cytotoxicity (mitotic index) and genotoxicity (chromosome aberration and micronucleus) endpoints between the negative control group and the exposed groups. However, the comet assay in fish revealed a DNA damage increase in animals exposed to the 30 % concentration of the macrophyte effluent and two concentrations of the activated sludge treatment effluent (10 and 75 %), which suggests that these two treatment systems may increase wastewater genotoxicity.     

CO<Subscript>2</Subscript>-driven large mafic explosive eruptions: the Pozzolane Rosse case study from the Colli Albani Volcanic District (Italy)

Generally, the intensity and magnitude of explosive volcanic activity increase in parallel with SiO₂ content. Pyroclastic-flow-forming eruptions in the Colli Albani ultrapotassic volcanic district (Italy) represent the most striking exception on a global scale, with volumes on the order of tens of cubic kilometres and K-foiditic compositions (SiO₂ even <42 wt.%). Here, we reconstruct the pre-eruptive scenario and event dynamics of the ~456 ka Pozzolane Rosse (PR) eruption, the largest mafic explosive event of the Colli Albani district. In particular, we focus on the driving mechanisms for the unusually explosive eruption of a low-viscosity, mafic magma. Geologic, petrographic and geochemical data with mass balance calculations, supported by experimental data for Colli Albani magma compositions, provide evidence for significant ingestion of carbonate wall rocks by the Pozzolane Rosse K-foiditic magma. Moreover, the scattered occurrence of cored bombs in Pozzolane Rosse pyroclastic-flow deposits records carbonate entrainment even at the eruptive time scale, as also tested quantitatively by thermal modelling of magma–carbonate interaction and carbonate assimilation experiments. We suggest that the addition of free CO₂ from decarbonation of country rocks was the major factor controlling magma explosivity. High CO₂ activity in the volatile component, coupled with magma depressurisation, produced extensive leucite crystallisation at short time scales, resulting in a dramatic increase in magma viscosity and volatile pressurisation, which was manifested a change of eruptive dynamics from early effusion to the Pozzolane Rosse's highly explosive eruption climax.     

Probing crustal anisotropy by receiver functions at the deep continental drilling site KTB in Southern Germany

Seismic anisotropy is a unique observational tool for remotely studying deformation and stress within the Earth. Effects of anisotropy can be seen in seismic data; they are due to mineral alignment, fractures or layering. Seismic anisotropy is linked to local stress and strain, allowing modern geophysics to derive geomechanical properties from seismic data for supporting well planning and fracking. For unravelling anisotropic properties of the crust, the teleseismic receiver functions methodology has started to be widely applied recently due to its ability in retrieving the three-dimensional characteristics of the media sampled by the waves. The applicability of this technique is tested here by a field test carried out around the Kontinental Tiefbohrung site in southeastern Germany. We compare our results to previous investigations of the metamorphic rock pile of the Zone Erbendorf-Vohenstrauss, drilled down to 9 km depth, which sampled an alternating sequence of paragneiss and amphibolite, in which a strong foliation has been produced by ductile deformation. The application of the receiver functions reveals the presence of two distinct anisotropic layers within the metamorphic rock pile at 0–4 km and below 6 km depth, with up to 8% anisotropy; the depth of these two layers corresponds to the location of mica-rich paragneiss which show intense foliation, and finally proves the relation between the signal in the receiver functions, rock texture and presence of cracks. We have now the capability of providing insights from passive seismic data on geomechanical properties of the rocks, useful for geological exploration and engineering purposes, which will help influencing expensive drilling decisions thanks to future application of this seismic technique.     

Biogeomorphology of the Mediterranean Posidonia oceanica seagrass meadows

Here we review the multiple interactions between the endemic Mediterranean seagrass, Posidonia oceanica, and coastal geomorphologic processes as an outstanding example of biogeomorphology, taking into account recent advances in the field. Seagrass meadows are among the most important elements for the functioning of marine coastal ecosystems, and represent a major focus for research and conservation. Being considered a priority habitat, P. oceanica meadows are protected by several European Union directives and national laws. In this paper we examine: the role of sedimentary features in controlling the development of the meadows; the interplay between P. oceanica leaf litter (i.e. beached necromass) cast ashore and erosional‐depositional processes on the beaches; the interactions between meadows and nearshore hydrodynamics, and; possible linkages between geomorphological features of the seafloor and the architecture of meadows. Finally, we provide perspectives for future research on P. oceanica and other Mediterranean seagrass meadows in a biogeomorphological context with specific reference to climate change. Copyright © 2016 John Wiley & Sons, Ltd.     

Numerical analysis of projectile penetration and perforation of plain and fiber reinforced concrete slabs

The research presented in this paper deals with the numerical analysis of projectile impact on regular strength concrete (RSC), high‐strength concrete (HSC), and engineered cementitious composites (ECC) using the Lattice Discrete Particle Model (LDPM). The LDPM is chosen in this study as it naturally captures the failure mechanisms at the length scale of coarse aggregate of concrete, and its capabilities include the accurate depiction of both intrinsic and apparent rate effects in concrete, as well as fiber reinforcement effects. The model is used to predict the experimental impact response performed by four independent testing laboratories, and for each data set the model parameters are calibrated and validated using a combination of uniaxial compression, triaxial compression, uniaxial strain compression, and dogbone tests. In the first study, perforation experiments on RSC and HSC for varied impact velocities are carried out, and the exit velocity is compared with the available experimental data. The second study focuses on ECC, where multiple impact of steel and plastic fiber reinforced concrete panels are explored. A third investigation is performed on four RSC panels with varied thicknesses and subjected to the same impact velocity. In this instance, the model is used to predict the penetration depths for the different cases. Finally, in the last study, the response of large‐thickness infinite panels of sizes ranging from 300 mm to 700 mm under projectile impact is considered. Copyright © 2016 John Wiley & Sons, Ltd.     

Variable sequence of events during the past seven terminations in two deep-sea cores from the Southern Ocean

The relationships among internally consistent records of summer sea-surface temperature (SSST), winter sea ice (WSI), and diatomaceous stable isotopes were studied across seven terminations over the last 660 ka in sedimentary cores from ODP sites 1093 and 1094. The sequence of events at both sites indicates that SSST and WSI changes led the carbon and nitrogen isotopic changes in three Terminations (TI, TII and TVI) and followed them in the other four Terminations (TIII, TIV, TV and TVII). In both TIII and TIV, the leads and lags between the proxies were related to weak glacial mode, while in TV and TVII they were due to the influence of the mid-Pleistocene transition. We show that the sequence of events is not unique and does not follow the same pattern across terminations, implying that the processes that initiated climate change in the Southern Ocean has varied through time.     

Short-term bacterial reactivity of nitrogen-enriched seawater of a eutrophic lagoon

We carried out, in September, a 24 h experiment to determine the potential reactivity of bacterial communities found in the sea water in Arcachon Basin (France). To create eutrophic systems, batches of seawater were enriched with 30 mgl^?1 of either ammonium chloride or amino acids. Samples were taken every 3 h. Quantitative measurements were made of direct counts (AODC), biomass and ATP content. The heterotrophic bacterial communities were defined in terms of their catabolic potentialities and ‘specific’ diversity. Bacterial heterotrophic activity was established by measuring heterotrophic uptake and the mineralization percentage of labelled glucose or amino acids. From these data, ratios of AMP/ATP and P/B were calculated where P is the uptake of labelled substrate and B is the biomass.After the nitrogen enrichment an increase of the respiration was seen at first. After 6 h, a biomass peak appeared associated with a continuous increase in the number of cells. Bacterial growth was concurrent with a qualitative modification of the community: UAI increased, and diversity dropped. A less diversified community resulted suggesting an immature ecological state (zymogenous bacterial). Low values of respiration percentage (20%) characterized high growth yields.