Occurrence and distribution of per-and polyfluoroalkyl substances (PFAS) in surface and groundwaters in an urbanized and agricultural area, Southern Brazil.

Per- and polyfluoroalkyl substances, known as PFAS, are emerging contaminants detected in surface water, groundwater, drinking water, air, and food. Due to its chemical stability and high hydrophobicity, these compounds are used as surfactants, surface protectors, flame retardants, textile impregnation, fire-fighting foam, and pesticides and may be a risk for human health in the long-term exposure. Currently, a little research has been carried out for these compounds in Brazil. In this study, the concentration and distribution of 23 PFAS were analyzed in groundwater samples collected from water wells in urbanized areas and in surface water samples from Porto Alegre, one of the biggest cities in Brazil. The total concentrations of PFAS (ΣPFAS) in a groundwater sample varied between 22 and 718 ng L-1. Eleven PFAS species were detected in groundwater, including PFOA, PFHxA, PFPeA, PFBA, PFDA, PFNA, and PFOS. Most of PFAS were quantified in samples located in the aquifer formed by medium to coarse sands intercalated with silty-sandy lenses and low organic matter content that could facilitate the percolation of these compounds. The total concentrations of PFAS (ΣPFAS) in a surface water sample varied between 11 and 17 ng L-1. Ten species were founded in surface water being PFOA, PFOS, and PFHpA the most dominant. Considering all the samples, PFOA was the predominant species in the study. In addition, tributary water bodies had higher concentrations of PFAS than the main water body (Guaiba Lake) probably due dilution process.

Unraveling the occurrence of contaminants of emerging concern in groundwater from urban setting: A combined multidisciplinary approach and self-organizing maps.

In recent decades, changes in human behavior and new technologies have introduced thousands of new compounds into the environment called "contaminants of emerging concern" (CEC). These compounds have been detected in different environmental compartments such as soil, surface water, air, and groundwater. The presence of these contaminants in groundwater may pose risks to human health when used as potable water. In some urban areas in Brazil, groundwater is normally consumed without previous treatment. This study aimed to use statistical analysis by self-organizing maps (SOM) to evaluate the trends of CEC in urban groundwater systems. A total of 23 CEC compounds including pesticides, pharmaceuticals, and hormones were determined in groundwater samples using solid phase extraction and liquid chromatography-mass spectrometry. The CEC most frequently detected were atrazine and degradation products, fipronil, simazine, tebuconazole, hexazinone, and caffeine in concentrations up to 300 ng L-1. All studied compounds were detected in groundwater at least in one sample. Patterns in the data through SOM have shown a strong positive correlation between atrazine, hexazinone, simazine, tebuthiuron, 2-hydroxyatrazine, and 17ß-estradiol. The hormones estrone and testosterone also show a positive correlation due to their similar chemical properties. On the other hand, caffeine was detected in 90% of the samples, likely due to a population habit of taking daily a hot drink made of yerba mate associated with low rates of treated domestic sewage in the study area.

Transport of emerging contaminants: a column experimental study in granitic, gneissic, and quaternary alluvial soils from Porto Alegre, Southern Brazil.

Emerging contaminants is a topic that has been in evidence, especially in the last decades. These compounds are pesticides, pharmaceuticals, and personal care products that are present in several locations, mainly in large urban centers. The aim of this work was to investigate the fate of seven compounds (atrazine, simazine, ametrine, tebuthiuron, 2,4-D, fipronil, and diclofenac) using leaching column experiments to evaluate accumulation and transfer in 5 different types of urban soils from Porto Alegre, Southern Brazil. Chemical analyses were carried out through liquid chromatography tandem mass spectrometry (LC-MS/MS). The results showed that the soil derived from quaternary sediments, with well-sorted sandy sediments, was the one in which the contaminants had higher mobility. This soil also has a pH above the average of the others in the city, a factor that may also be responsible for less retention of substances. Tebuthiuron is the substance with the greatest leaching potential overall. Column experiments are a relevant tool to understand the behavior of emerging contaminants in soils and implications on the population health.