Pontifícia Universidade Católica do Rio de Janeiro

An unprecedented oil spill occurred along the Northeast Coast of Brazil in late 2019, affecting the Environmental Protection Area Costa dos Corais (APACC), the largest Brazilian marine conservation unit, posing a risk to this complex ecosystem. By applying passive ecotoxicological biomonitoring, this study aimed to evaluate whether the remaining contamination from such an oil spill affected the population of the marine clam Tivela mactroides by assessing multiple biomarkers, regarding antioxidant enzyme activities (SOD, CAT), biotransformation (GST, GSH), oxidative damage (MDA), and neurotoxicity (AChE) in gills and digestive glands, and PAH bioaccumulation. The clam tissues and sediment were sampled in three locations (Paripueira, Japaratinga and Maragogi beaches), which were differently affected by the accident, and during three sampling periods, starting one year after the accident began. We detected Σ16PAHs in the clam soft tissues and in the sediment samples, all with lower concentrations. Differential biomarker responses were observed in both clam tissues, as denoted by the Integrated Biomarker Response Index (IBR). However, there was no correlation between PAH bioaccumulation and biomarker responses in T. mactroides, suggesting the occurrence of multiple stress factors in such a marine protected area. This study demonstrated that multiple biomarkers assessment in the marine clam T. mactroides is a suitable approach for biomonitoring of marine areas in Brazil affected by the 2019 oil spill. However, we emphasize that further long-term studies must be conducted to better understand the environmental impacts caused by an oil spill of such magnitude.

CO₂-foams offer a promising route to reduce the carbon footprint of oilfield operations, yet their stability is challenged by rapid coarsening due to the high solubility of CO₂ in water.A critical gap remains because foam formulations are typically screened at atm. pressure but deployed at elevated subsurface pressures, where foam behavior and stabilizer effectiveness can differ significantly.This study is the first to systematically link the influence of nanoparticle (NP) concentration and NP-surfactant interactions on CO₂-foam stabilization between 1 bar (used for rapid screening) and 40 bar (relevant to reservoir conditions).Oppositely charged nanoparticles (SiO₂ and Al₂O₃) were combined with an amphoteric surfactant to promote stronger interactions under CO₂-acidified conditions during foam generation.Results show that atm. screening underestimates foam stability and overestimates NP requirements by two orders of magnitude.At 1 bar, 1.0 wt% NP achieved moderate stability (t_1/2 = 160 s), whereas at 40 bar, only 0.01 wt% NP produced much greater stability (t_1/2 = 857 s).This difference is attributed to the requirement for gel-like NP-surfactant networks in the bulk phase at low pressure to suppress drainage, whereas at high pressure, stabilization primarily occurs through strong interfacial NP adsorption, which mitigates coarsening.Our findings challenge conventional screening practices and provide a new framework for designing CO₂-foams, reducing NP usage, optimizing costs, and enhancing the viability of CO₂ storage technologies.

A luminescence-based method was developed to detect gentamicin using silver nanoparticles (AgNPs) associated with nitrogen-doped graphene quantum dots (N-GQDs). When gentamicin sulfate interacts with the AgNPs/N-GQDs system, the characteristic blue fluorescence of N-GQDs, which had been previously turned off by AgNPs, is restored. Under specific conditions (such as the amount of synthesis dispersion and pH), this AgNPs/N-GQDs probe enabled quantification of gentamicin ranging from 3.0 × 10^-7 to 6.0 × 10^-6 mol L^-1. To address interference from other substances during the analysis, a solid-phase extraction, with a kanamycin-imprinted polymer cartridge, enabled accurate results. Two veterinary pharmaceutical samples were used to test the method and results were in agreement with those achieved by obtained using high-performance liquid chromatography with analyte chemical derivatization. This new method is straightforward, sensitive, and selective, and it is also considered eco-friendly (0.63 score Analytical greenness calculator) since it avoids the use of toxic chemical derivatization reagents, use nanoquantities of carbon and silver based nanomaterials and aqueous systems.