Using NdSr isotopes in suspended sediments in the Abrolhos coral-reef (SW Atlantic, Brazil) to assess potential contamination from the 2015 Fundão dam collapse.

The Abrolhos bank is home of the richest coral reef system of the Southwestern Atlantic, where endemic coral species are found. It has been reported that Abrolhos' corals are under intense stress due to increasing of Marine Heat Waves during the last decades. Additionally, anthropic interventions along the adjacent coastal regions are a factor of concern since they contribute to the increase in the sediment load and to organic debris input in the reef domain. In November 2015, the collapse of the Fundão mining tailings dam resulted in the release of approximately 50 million m3 of iron oxide and quartz-rich slurry into the Doce River. Aiming at using a fingerprint of the tailings and to assess the presence of traces of the Fundão dam material from this event on the Abrolhos bank, this work presents new 87Sr/86Sr and 143Nd/144Nd isotope ratios of marine suspended sediment samples collected between 2016 and 2020 from a network of sediment traps throughout the reef and complementary suspended material at sea. In parallel, we monitored meteo-oceanographic parameters and modeled surface marine currents as an attempt to identify the sediment transport between the Doce River mouth and Abrolhos bank. The r isotopes were used as provenance proxies based on the fact that minerals and rocks tend to have specific isotopic signatures reflecting their own geological derivation. In this context, the isotopic ratios of various potential regional sources for the sedimentation in Abrolhos bank were evaluated. Our monitoring and isotopic measurements indicate that Doce River signatures are detected at Abrolhos bank, following the seasonal Doce River discharge at sea. Isotopic signature of Doce River at Abrolhos bank was also observed during the austral winter (July-August) when cold fronts migrate at the Brazilian coast with higher frequency and energy.

Assessment of physical-chemical characteristics of water and sediments from a Brazilian tropical estuary: status and environmental implications.

The environmental quality of the Jacuípe River's estuary (very important in northeastern Brazil) was assessed during 2007 and 2008. In water, concentrations (mg L⁻¹) of NO2⁻ (<0.004 to 0.016), NO3⁻ (0.01 to 0.33), soluble PO4³â» (<0.02 to 0.22), dissolved oxygen (3.9 to 9.6), total contents (mg L⁻¹) of Cd (<0.001), Cu (<0.01), Pb (<0.01), and Zn (<0.1), pH (5.60 to 8.00), and electrical conductivity (0.12 to 48.60 mS cm⁻¹) agreed with environmental standards. In sediments, clay and total organic matter (%, m/m) varied, respectively, from 8.8 to 12.0 and from 1.1 to 8.8, while infrared, thermogravimetric profile, electronic micrograph, as well as X-Ray analyses showed desirable adsorptive characteristics. However, maximum exchangeable levels (mg kg⁻¹) of Cd (1.3), Cu (44.6), Pb (35.7), and Zn (43.7) and their respective maximum pseudototal concentrations (mg kg⁻¹): 19.4, 95.1, 68.2, and 30.3 were below the recommended limits. In this sense, it was possible to demonstrate good environmental preservation even with the growing number of industries and touristic activities in the evaluated estuarine area.

Evaluation of photodynamic activity of octaethylporphyrin and vanadyl octaethylporphyrin

Objective: in this work we have investigated the photodynamic efficiency of octaethylporphyrin (OEP) and vanadyl octaethylporphyrin(VOOEP). Methods: this study was performed by the evaluation of photophysical parameters of these porphyrins, the photooxidationrate constants (kf) of the biomolecules (tryptophan -Trp and bovine serum albumin - BSA) and the erythrocytes photodestructionpercentage. Results: photophysical parameters value such as singlet oxygen quantum yield (Õ∆) and triplet state lifetime (ôT)indicated that OEP (Õ∆= 0.64 ±0.02, tT= 0.91 ± 0.02 ms) is more efficient than VOOEP (Õ∆= 0.26 ±0.02, tT= 0.22 ± 0.03ms). The values of kf/10-4 s-1for Trp and BSA photoxidation demonstrated that OEP (Trp= 2.80 ± 0.05 and BSA= 2.50 ± 0.1)is more efficient than VOOEP (Trp= 0.81 ± 0.08 and BSA= 0.62 ± 0.04). The photodestruction percentage of erythrocytesrevealed that the photodynamic activity of OEP is more pronounced than photoactivity of VOOEP. These results indicated thatdifferences observed in the photodynamic activity between the porphyrins could be associated with differences in their molecularstructures. Conclusion: photophysical parameters, photooxidation of biomolecules, and photodestruction of erythrocytes clearlyindicate that the vanadyl group (V=O) interferes in the photoactivity of OEP, causing a considerable reduction in its efficiency.