Bayesian inference and wind field statistical modeling applied to multiple source estimation.

We present a methodology to identify multiple pollutant sources in the atmosphere that combines a data-driven dispersion model with Bayesian inference and uncertainty quantification. The dispersion model accounts for a realistic wind field based on the output of a multivariate dynamic linear model (DLM), estimated from measured wind components time series. The forward problem solution, described by an adjoint transient advection-diffusion partial differential equation, is then obtained using an appropriately stabilized finite element formulation. The Bayesian inference tool accounts for uncertainty in the concentration data and automatically states the balance between the prior and the likelihood. The source parameters are estimated by a Metropolis in Gibbs Monte Carlo Markov chain (MCMC) algorithm with adaptive steps. The MCMC algorithm is initialized with a maximum a posteriori estimator obtained with particle swarm optimization to accelerate convergence. Finally, the proposed methodology seems to outperform inversion techniques from previous works.

Long-term monitoring projects of Brazilian marine and coastal ecosystems.

Biodiversity assessment is a mandatory task for sustainable and adaptive management for the next decade, and long-term ecological monitoring programs are a cornerstone for understanding changes in ecosystems. The Brazilian Long-Term Ecological Research Program (PELD) is an integrated effort model supported by public funds that finance ecological studies at 34 locations. By interviewing and compiling data from project coordinators, we assessed monitoring efforts, targeting biological groups and scientific production from nine PELD projects encompassing coastal lagoons to mesophotic reefs and oceanic islands. Reef environments and fish groups were the most often studied within the long-term projects. PELD projects covered priority areas for conservation but missed sensitive areas close to large cities, as well as underrepresenting ecosystems on the North and Northeast Brazilian coast. Long-term monitoring projects in marine and coastal environments in Brazil are recent (<5 years), not yet integrated as a network, but scientifically productive with considerable relevance for academic and human resources training. Scientific production increased exponentially with project age, despite interruption and shortage of funding during their history. From our diagnosis, we recommend some actions to fill in observed gaps, such as: enhancing projects' collaboration and integration; focusing on priority regions for new projects; broadening the scope of monitored variables; and, maintenance of funding for existing projects.

Niche availability and habitat affinities of the red porgy Pagrus pagrus (Linnaeus, 1758): An important ecological player on the world's largest rhodolith beds.

The red porgy (Pagrus pagrus) is a carnivore bottom dweller sparid, inhabiting flat sandy bottoms, rhodolith and seagrass beds of the Mediterranean Sea, the Western Atlantic (from Florida to Argentina) and the Eastern Atlantic (from Britain to Gabon). Along its native range, the red porgy is highly targeted by commercial and artisanal fisheries. In the past 40 years, the population decline of the species has been widely reported. In many locations, such as the Brazilian coast, stocks have collapsed. The central portion of the Brazilian coast harbours the largest rhodolith beds in the world and the highest levels of nektonic and benthic biodiversity. Along the rhodolith megahabitat, P. pagrus density is disproportionately higher (by 480%) than that of conspicuous benthic fishes inhabiting the same environment. Despite the ecological and economic importance of such an important species along its native range, little is known regarding its habitat use, niche availability and population responses to global warming. Here we present habitat affinities based on data sampled using baited remote stereo-video systems, and modelled niche availability and global warming populational responses. Our findings reveal that the red porgy is a species highly associated with rhodolith beds along the central portion of the Brazilian coast. The presence of a disproportional density and biomass of the red porgy, compared to other marine fish species, indicates that the species plays a key ecological role as a carnivore, mesoconsumer and prey/predator tolerant species, maintaining essential ecological functions in the habitat. In a global warming scenario, the model predicted populational niche shifts poleward and a severe niche erosion at lower latitudes as expected. Conservation initiatives (implementation of Maine Protected Areas, trawling exclusion zones, mining exclusion zones, fisheries management policies) are urgent to secure future stocks of the red porgy and also preserve the fragile rhodolith beds they inhabit.

Effective killing of bacteria under blue-light irradiation promoted by green synthesized silver nanoparticles loaded on reduced graphene oxide sheets.

Graphene oxide (GO) materials loaded with silver nanoparticles (AgNPs) have drawn considerable attention due to their capacity to efficiently inactivate bacteria though a multifaceted mechanism of action, as well as for presenting a synergetic effect against bacteria when compared to the activity of AgNPs and GO alone. In this investigation, we present an inexpensive and environmentally-friendly method for synthesizing reduced GO sheets coated with silver nanoparticles (AgNPs/r-GO) using a coffee extract solution as a green reducing agent. The physical and chemical properties of the produced materials were extensively characterized by scanning electron microscopy (SEM), field-emission gun transmission electron microscopy (FEG-TEM), ultraviolet and visible absorption (UV-Vis), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES) and ion release determination. The results demonstrated that AgNPs/r-GO composites were successfully produced, revealing the formation of micrometer-sized r-GO sheets decorated by AgNPs of approximately 70 nm diameter. Finally, bactericidal and photobactericidal effects of the AgNPs/r-GO composites were tested against Staphylococcus aureus, in which the results showed that the composites presented antimicrobial and photoantimicrobial activities. Moreover, our results demonstrated for the first time, to our knowledge, that an efficient process of bacterial inactivation can be achieved by using AgNPs/r-GO composites under blue light irradiation as a result of three different bacterial killing processes: (i) chemical effect promoted by Ag+ ion release from AgNPs; (ii) photocatalytic activity induced by AgNPs/r-GO composites, enhancing the bacterial photoinactivation due to the excited-Plasmons of the AgNPs when anchored on r-GO; and (iii) photodynamic effect produced by bacterial endogenous photosensitizers under blue-light irradiation. In summary, the present findings demonstrated that AgNPs/r-GO can be obtained by a non-toxic procedure with great potential for biomedical-related applications.

Habitat fragmentation caused by contaminants: Atrazine as a chemical barrier isolating fish populations.

Information on how atrazine can affect the spatial distribution of organisms is non-existent. As this effect has been observed for some other contaminants, we hypothesized that atrazine-containing leachates/discharges could trigger spatial avoidance by the fish Poecilia reticulata and form a chemical barrier isolating upstream and downstream populations. Firstly, guppies were exposed to an atrazine gradient in a non-forced exposure system, in which organisms moved freely among the concentrations, to assess their ability to avoid atrazine. Secondly, a chemical barrier formed by atrazine, separating two clean habitats (extremities of the non-forced system), was simulated to assess whether the presence of the contaminant could prevent guppies from migrating to the other side of the system. Fish were able to avoid atrazine contamination at environmentally relevant concentrations (0.02 µg L-1), below those described to cause sub-lethal effects. The AC50 (atrazine concentration causing avoidance to 50% of the population) was 0.065 µg L-1. The chemical barrier formed by atrazine at 150 µg L-1 (concentration that should produce an avoidance around 82%) caused a reduction in the migratory potential of the fish by 47%; while the chemical barrier at 1058 µg L-1 (concentration that produces torpidity) caused a reduction in the migratory potential of the fish by 91%. Contamination by atrazine, besides driving the spatial distribution of fish populations, has potential to act as a chemical barrier by isolating fish populations. This study includes a novel approach to be integrated in environmental risk assessment schemes to assess high-tier contamination effects such as habitat fragmentation and population displacement and isolation.