Bioaccumulation and trophic transfer of per- and polyfluoroalkyl substances in a subtropical mangrove estuary food web.

Mangrove estuaries are an important land-sea transitional ecosystem that is currently under various pollution pressures, while there is a lack of research on per- and polyfluoroalkyl substances (PFAS) in the organisms of mangrove estuaries. In this study, we investigated the distribution and seasonal variation of PFAS in the tissues of organisms from a mangrove estuary. The PFAS concentrations in fish tissues varied from 0.45 ng/g ww to 17.67 ng/g ww and followed the order of viscera > head > carcass > muscle, with the highest tissue burden found in the fish carcass (39.59 ng). The log BAF values of PFDoDA, PFUnDA, and PFDA in the whole fish exceeded 3.70, indicating significant bioaccumulation. The trophic transfer of PFAS in the mangrove estuary food web showed a dilution effect, which was mainly influenced by the spatial heterogeneity of PFAS distribution in the estuarine environment, and demonstrated that the gradient dilution of PFAS in the estuary habitat environment can disguise the PFAS bio-magnification in estuarine organisms, and the larger the swimming ranges of organisms, the more pronounced the bio-dilution effect. The PFOA-equivalent HRs of category A and B fish were 3.48-5.17 and 2.59-4.01, respectively, indicating that mangrove estuarine residents had a high PFAS exposure risk through the intake of estuarine fish.

Uptake and cellular responses of Microcystis aeruginosa to PFOS in various environmental conditions.

Although PFOS has been banned as a persistent organic pollutant, it still exists in large quantities within the environment, thus impacting the health of aquatic ecosystems. Previous studies focused solely on high PFOS concentrations, disregarding the connection with environmental factors. To gain a more comprehensive understanding of the PFOS effects on aquatic ecosystems amidst changing environmental conditions, this study investigated the cellular responses of Microcystis aeruginosa to varying PFOS concentrations under heatwave and nutrient stress conditions. The results showed that PFOS concentrations exceeding 5.0 µg/L had obvious effects on multiple physiological responses of M. aeruginosa, resulting in the suppression of algal cell growth and the induction of oxidative damage. However, PFOS concentration at levels below 20.0 µg/L has been found to enhance the growth of algal cells and trigger significant oxidative damage under heatwave conditions. Heatwave conditions could enhance the uptake of PFOS in algal cells, potentially leading to heightened algal growth when PFOS concentration was equal to or less than 5.0 µg/L. Conversely, deficiency or limitation of nitrogen and phosphorus significantly decreased algal abundance and chlorophyll content, inducing severe oxidative stress that could be mitigated by exposure to PFOS. This study holds significance in managing the impact of PFOS on algal growth across diverse environmental conditions.

Per- and polyfluoroalkyl substances (PFASs) in water and sediment from a temperate watershed in China: Occurrence, sources, and ecological risks.

Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic organic fluorides that have been widely used in various industrial and consumer applications. However, their potential ecological risks have raised concerns. In this study, PFASs were investigated in different environmental media in the Jiulong River and Xiamen Bay regions of China, revealing widespread contamination of PFASs in the watershed. PFBA, PFPeA, PFOA, and PFOS were detected in all 56 sites, with short-chain PFASs dominating (72 % of the total). Novel PFAS alternatives, including F53B, HFPO-DA, and NaDONA, were detected in >90 % of the water samples. Seasonal and spatial variations in PFAS concentrations were observed in the Jiulong River estuary, while Xiamen Bay was not significantly affected by seasonal changes. In sediment, PFSAs were dominant with long-chains while PFCAs with short-chains, and the occurrence was influenced by water depth and salinity. PFSAs were more inclined to be adsorbed in sediments than PFCAs, and log Kd of PFCAs increased with the numbers of -CF2-. Paper packaging, machinery manufacturing, WWTP discharge, airport and dock activities were the dominant sources of PFASs. Risk quotient showed that PFOS or PFOA may pose high toxicity to Danio rerio and Chironomus riparius. Although the overall ecological risk in the catchment is still low, the hazard of bio-concentration under long-term exposure and multi-pollutant synergistic toxicity cannot be ignored.