Increased levels of perfluorooctanesulfonic acid (PFOS) during Hurricane Dorian on the east coast of Florida.

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals commonly found in everyday consumer products and are an emerging concern due to their ubiquitous presence in ecosystems around the world. PFAS exposure, which often occurs through contaminated water, has been linked to several adverse health effects in humans and wildlife. PFAS can be transported in surface water and storm runoff in the nearshore environment. Episodic events, such as hurricanes, are projected to increase in frequency and intensity, and a critical unanswered question is: how do episodic events influence the concentrations and distributions of emerging contaminants, such as PFAS, in coastal systems? Here, we investigated the impact of the 2019 Hurricane Dorian on the Florida coast to assess how natural disasters, such as hurricanes, influence the fate and transport of PFAS in surface water. Water samples collected throughout the St. Augustine Intracoastal waterway before, during, and after the storm were analyzed and compared with baseline concentrations. Ultra-high-pressure liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) was used in the detection and quantification of 23 and 17 PFAS, respectively. Perfluorooctane sulfonic acid (PFOS) was the compound with the highest concentration across all sampling sites. Mean PFOS levels showed the highest increase of 177% during the hurricane and returned to baseline levels after two days. Our findings highlight the need for continued research focused on understanding how large storms near all coastlines can impact the transport of environmental pollutants, such as PFOS, that can have adverse effects on human and environmental health. Further monitoring of PFAS in coastal systems is necessary to identify potential PFAS hotspots, investigate the impacts of episodic events on PFAS transport, develop mitigation practices capable of reducing the risk of PFAS exposure.

Characterization of Bacterial and Fungal Communities Reveals Novel Consortia in Tropical Oligotrophic Peatlands.

Despite their importance for global biogeochemical cycles and carbon sequestration, the microbiome of tropical peatlands remains under-determined. Microbial interactions within peatlands can regulate greenhouse gas production, organic matter turnover, and nutrient cycling. Here we analyze bacterial and fungal communities along a steep P gradient in a tropical peat dome and investigate community level traits and network analyses to better understand the composition and potential interactions of microorganisms in these understudied systems and their relationship to peatland biogeochemistry. We found that both bacterial and fungal community compositions were significantly different along the P gradient, and that the low-P bog plain was characterized by distinct fungal and bacterial families. At low P, the dominant fungal families were cosmopolitan parasites and endophytes, including Clavicipitaceae (19%) in shallow soils (0-4 cm), Hypocreaceae (50%) in intermediate-depth soils (4-8 cm), and Chaetothyriaceae (45%) in deep soils (24-30 cm). In contrast, high- and intermediate-P sites were dominated by saprotrophic families at all depths. Bacterial communities were consistently dominated by the acidophilic Koribacteraceae family, with the exception of the low-P bog site, which was dominated by Acetobacteraceae (19%) and Syntrophaceae (11%). These two families, as well as Rhodospirillaceae, Syntrophobacteraceae, Syntrophorhabdaceae, Spirochaetaceae, and Methylococcaceae appeared within low-P bacterial networks, suggesting the presence of a syntrophic-methanogenic consortium in these soils. Further investigation into the active microbial communities at these sites, when paired with CH4 and CO2 gas exchange, and the quantification of metabolic intermediates will validate these potential interactions and provide insight into microbially driven biogeochemical cycling within these globally important tropical peatlands.

Multiple biomarkers highlight the importance of water column processes in treatment wetland organic matter cycling.

A suite of biomarkers, including amino acids, pigments, and lignin phenols coupled with high resolution mass spectrometry were used to evaluate differences in the sources and fate of organic matter (OM) in Everglades treatment wetlands as a model for OM cycling in shallow water wetlands. Five components of the system (water column particulate matter, vertical traps, flocculent material, periphyton, and surface soil) were assessed for OM transformations down-profile (i.e. water column to soil) and between treatment cells dominated by emergent aquatic vegetation (EAV) and submerged aquatic vegetation (SAV), with comparisons to reference sites within the remnant Everglades. We found that OM cycling is fundamentally different between EAV and SAV wetlands, and that SAV wetlands have some shared characteristics with similar habitats in the remnant Everglades. Other than locations densely populated by Typha spp., water column particulate organic C was predominantly derived from microbial/cryptomonad sources, rather than macroscopic sources (vascular plants and algal mats). Bacterial amino acid biomarkers were positively correlated with amino acid degradation indices and organic P (Po), respectively suggesting that microbial abundance is associated with less degraded OM, and that further investigation into relationships between microbial biomass and Po is warranted. Overall, this multi-biomarker approach can elucidate the relative degradation of OM pools, identify sources of OM, and highlight the importance of water column processes in shallow water wetlands.