Jacobs Engineering Group

Per- and polyfluoroalkyl substances (PFAS) pose a significant health threat due to their environmental persistence and toxicity. While PFAS contamination is widespread in Florida, the state currently lacks fish consumption advisories (FCAs) for these compounds, despite existing FCAs for legacy pollutants. This study quantified 40 PFAS in edible muscle tissue from 264 fish (16 species) across four estuaries along Florida's Atlantic coast to assess ecological and human health risks. The highest concentrations of total PFAS were found in Red Drum (Sciaenops ocellatus; 0.209 - 51.6 ng/g wet weight) and Spotted Seatrout (Cynoscion nebulosus; 2.01 - 24.3 ng/g ww) in the Indian River Lagoon, where up to 68% of Red Drum and 75% of Spotted Seatrout exceeded ecological quality standards, indicating potential impacts on predators. PFOS was the predominant PFAS, driving ecological and human health risks. Estimated daily intakes (EDIs) of PFOS exceeded the EPA reference dose (RfD) by up to 3 orders of magnitude, with the highest exposures concentrated in Red Drum and Spotted Seatrout from the Indian River Lagoon. These findings highlight that PFAS monitoring of tissue concentrations in fish across Florida's freshwater and marine systems would be needed for accurately quantifying exposure risks. Such efforts are fundamental to informing regulatory frameworks regarding FCAs and ensuring the long-term protection of aquatic ecosystems and human health.

Bridge strikes are events where overheight vehicles impact bridge superstructures, causing damage ranging from superficial to severe. When a bridge strike is discovered, the responsible agency must assess the damage and decide what, if any, action is required. This paper presents key results of a detailed survey that gathered information about current state highway agency practices related to bridge strikes, in support of a research project for the Illinois Department of Transportation (IDOT). Survey results indicate that most bridge strikes are located at girders, and damage may extend to other bridge elements-particularly diaphragms/cross-frames. Additionally, an analysis of National Bridge Inventory data indicates that low-clearance bridges tend to be older and are more likely to have a main span structural material of steel rather than concrete. Agency survey respondents reported, on average, using visual inspections, manual photographs, and manual measurements for documenting over 90% of bridge strike cases. Nondestructive testing is used in some states, while laser scanning and drone photography are innovative methods that have rarely been used to date, so there is potential to improve inspection efficacy by implementing these techniques. In general, states handle analysis and assessment on a case-by-case basis, exercising a significant amount of engineering judgment. Selection of repair methods for damaged steel girders depends on the damage severity. Finally, an overview of current IDOT practices for inspecting damaged steel girders is presented, and terrestrial laser scanning is discussed as a potential future method for damaged steel girder characterization.

This study elucidates the metabolic remodeling and synergistic mechanisms of the microalgae-bacteria symbiosis (MABS) under competitive nitrogen and phosphorus stress. Compared with the control, MABS increased removal efficiencies of total nitrogen, NH4+-N, NO3--N, and total phosphorus by 5.9, 5.1, 1.5, and 1.7 times, respectively, while enhancing microalgal triacylglycerol production by 17.5%. Microalgae preferentially assimilated NH4+-N and dominated phosphorus uptake, whereas the bacterial community strengthened denitrification through functional specialization, carbon metabolism optimization, and electron transport chain (ETC) remodeling. Specifically, bacterial carbon metabolism shifted from the conventional tricarboxylic acid cycle toward a frdABCD-dependent branch that supplies reducing power, accompanied by the enrichment of electron carrier ubiquinone-10 and upregulation of ETC complexes III/IV. Symbiotic bacteria further promoted more efficient ATP synthesis in microalgae, synergizing with improved carbon fixation and lipid-directed carbon partitioning. These findings reveal the metabolic plasticity and cross-kingdom coordination that underpin high-rate nutrient removal and lipid accumulation in MABS.

Abstract Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate are frequently detected in environmental media at and near locations where per- and polyfluoroalkyl substances have been released. Because of their persistence and relatively high bioaccumulation potential as well as the frequency and magnitude of detection at these locations, PFOS and perfluorohexane sulfonate are likely to be a key focus of site-specific ecological risk assessments (ERAs) used to assess the potential exposures of avian and mammalian wildlife to per- and polyfluoroalkyl substances. Toxicity reference values (TRVs) are a critical parameter of the collective modeling of exposure and effects to wildlife in food chain models used in site-specific ERAs and in deriving ecological screening values (ESVs) for abiotic media. This work reviewed published mammalian and avian laboratory toxicity studies with the goal of recommending TRVs for use in site-specific ERAs and ecological screening value derivation. Selection criteria prioritized oral exposure studies in birds and mammals evaluating effects on population-level apical endpoints, such as reproduction, growth, and survival. In all cases, reproductive effects were the most sensitive apical endpoint. The no-effect and low-effect avian TRVs for PFOS were 0.55 and 1.1 mg/kg-bw/d, respectively, as derived from a chronic dietary exposure study with Japanese quail (Cortunix japonica). For mammals, TRVs were derived from chronic dietary exposure studies in deer mice (Peromyscus spp.). The no-effect and low-effect mammalian TRVs for PFOS were 0.25 and 0.5 mg/kg-bw/d. Perfluorohexane sulfonate was an order of magnitude less toxic than PFOS, with no-effect and low-effect mammalian TRVs of 7 and 14 mg/kg-bw/d. Given that these TRVs are bracketed by other doses within relatively straightforward dose–response relationships and are based on chronic exposures that evaluated a variety of apical endpoints clearly linked to population-level ecological health, we believe that these TRVs are considered robust and are expected to be useful for site-specific ERAs and ecological screening value calculation.