Occurrence and potential ecological risks of PFAS in Pampulha Lake, Brazil, a UNESCO world heritage site.

Per- and polyfluoroalkyl substances (PFAS) comprise >4000 synthetic substances used in industrial applications and consumer products. PFAS used daily in households and manufacturing plants end up in domestic sewage, and industrial effluents can be discharged to surface water. Urban watersheds located in low and middle-income countries (LMIC), which lack sanitation infrastructure, are potential recipients of waste containing PFAS. Yet, only a few studies report PFAS occurrence in urban reservoirs and lakes, especially those located in the Global South due to resource limitations. This is the first study aimed to assess PFAS occurrence and ecological risks in Pampulha Lake, Brazil, a site which represents the reality of many other urban watersheds in LMIC as it is surrounded by densely populated areas and manufacturing plants. Surface water samples were collected monthly for 1 year from four sampling points at Pampulha Lake. Sample analysis was based on US Environmental Protection Agency Method 1633, which employs solid phase extraction followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Species sensitivity distribution (SSD) curves were built to identify potentially susceptible species based on detected water concentrations. Bioaccumulation was estimated for fish tissue. Short-chain (perfluorobutanesulfonic acid, PFBS and perfluorohexanoic acid, PFHxA) and long-chain PFAS (perfluorodecanoic acid, PFDA; perfluorooctanoic acid, PFOA; perfluorododecanoic acid, PFDoA; and perfluorooctanesulfonic acid, PFOS) were detected at the µg L-1 range. Total PFAS concentrations in the wet season were generally higher than in the dry season, likely due to limited capacity of the treatment plant processing water from tributaries which receive raw sewage. More than 5 % of aquatic species are potentially susceptible to chronic effects of PFOS at detected concentrations (0.2-2.2 µg L-1). Predicted bioaccumulation of PFOS in fish was above advisory diet intake levels for humans. Results emphasize the need for studies related to PFAS occurrence in watersheds located in LMIC.

Determination of rare earth elements in Fe-minerals using external calibration by LA-ICP-MS and application on Cauê Iron Formation (Brazil).

The rare earth elements (REE) composition in Fe-mineral phases is an important tool in iron formation studies to obtain information about parent rocks and environmental and paragenetic processes. However, the determination of REE presents some difficulties, such as the low concentration of these elements, matrix complexity and lack of iron matrix certified reference materials. The aim of the present work is to propose an analytical method to determine the REE plus Y (REE + Y) contents at trace levels in Fe-(hydr)oxides by the laser ablation ICP-quadrupoleMS technique, using external calibration. The calibration curves were obtained from analyses of reference materials with different matrices, and the analytical conditions were checked on the NIST 614 glass. The linearity (R2 ≥ 0.98), limit of detection (0.002-0.044 µg g-1), limit of quantification (0.008-0.146 µg g-1), recovery (88.4-112.4%), and intraday (0.1-14.1%) and interday (1.6-17.8%) precision were systematically assessed. The results obtained showed that the method is fit for the purpose and showed evidence of a nonsignificant interference of the matrix. Thus, the developed procedure was applied in the analyses of magnetite, martite, hematite, and goethite grains from Cauê Iron Formation (Brazil). The REE + Y patterns of the minerals are consistent with the previous study of bulk analyses on whole rocks and highlight the postdepositional signature of these elements in banded iron formations.