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Understanding the fate and transport of per- and polyfluoroalkyl substances (PFAS) at contaminated sites is crucial for effective remedial and regulatory decision-making. This interdisciplinary study offers a novel approach for estimating and mapping PFAS sorption properties and their impact on PFAS fate and transport. By integrating electromagnetic induction (EMI) surveys, physical and chemical sediment characterization, mineralogical characterization, and batch sorption experiments of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), we develop a comprehensive mapping of sorption dynamics. Sediments collected from a compound bar deposit were analyzed to establish correlations between EMI signal, sediment characteristics, and PFOA and PFOS sorption distribution coefficients (Kd). Sorption behavior and EMI response of these compounds were consistent with the sediments’ physical and chemical properties where Kd and electrical conductivity was higher with finer grain size, higher organic matter content, and higher aluminum and iron contents. The study demonstrates that EMI effectively maps PFAS sorption properties spatially, providing crucial insights into the sedimentological controls that govern both EMI responses and PFAS sorption. Correlation analysis yielded Pearson correlation values of 0.71 for EMI-PFOA Kd and 0.56 for EMI-PFOS Kd, underscoring the potential of EMI in predicting the spatial distribution of PFAS sorption in complex sedimentary environments. While these Pearson correlation values indicate moderate to strong correlations, their significance is amplified by the cost-effectiveness and extensive aerial coverage of EMI, the sparsity of sediment samples typically collected for batch sorption, and their spatial distribution. These results highlight the potential of EMI to identify sorption hotspots, thereby guiding targeted remediation efforts and enhancing site management strategies, ultimately reducing both costs and environmental impacts. 

Groundwater-surface water interaction (hyporheic exchange) is critical in numerous hydrogeochemical processes; however, hyporheic exchange is difficult to characterize due to the various spatial (e.g., sedimentary architecture) and temporal (e.g., stage fluctuations) variables that influence it. This interdisciplinary study brings forth novel insights by integrating various methodologies including geophysical surveys, physical and chemical sediment characterization, and water chemistry analysis to explore the interplay of the numerous facets governing hyporheic zone processes within a compound bar deposit. The findings reveal distinct sedimentary facies and geochemical zones within the compound bar, driven by the sedimentary architecture. Cross-bar channel fills are identified as critical structures influencing hydrogeochemical dynamics, acting as baffles to groundwater flow and modulating nutrient transformations. Geophysical imaging and hydrogeochemical analyses highlight the complex interplay between sediment characteristics and subsurface hydraulic connectivity, emphasizing the role of sediment heterogeneity in controlling hyporheic exchange and solute mixing. The study concludes that sediment heterogeneity, particularly the presence of cross-bar channel fills, plays a pivotal role in the hydrogeochemical dynamics of the hyporheic zone. These structures significantly influence hyporheic flow paths, solute residence times, and nutrient cycling, underscoring the necessity to consider the fine-scale sedimentary architecture in models of hyporheic exchange. The findings contribute to a deeper understanding of riverine ecosystem processes, offering insights that can inform management strategies for water quality and ecological integrity. 

Abstract Galactic compact binaries with orbital periods shorter than a few hours emit detectable gravitational waves (GWs) at low frequencies. Their GW signals can be detected with the future Laser Interferometer Space Antenna (LISA). Crucially, they may be useful in the early months of the mission operation in helping to validate LISA's performance in comparison to prelaunch expectations. We present an updated list of 55 candidate LISA-detectable binaries with measured properties, for which we derive distances based on Gaia Data Release 3 astrometry. Based on the known properties from electromagnetic observations, we predict the LISA detectability after 1, 3, 6, and 48 months using Bayesian analysis methods. We distinguish between verification and detectable binaries as being detectable after 3 and 48 months, respectively. We find 18 verification binaries and 22 detectable sources, which triples the number of known LISA binaries over the last few years. These include detached double white dwarfs, AM CVn binaries, one ultracompact X-ray binary, and two hot subdwarf binaries. We find that across this sample the GW amplitude is expected to be measured to ≈10% on average, while the inclination is expected to be determined with ≈15° precision. For detectable binaries, these average errors increase to ≈50% and ≈40°, respectively. 

ABSTRACT We report the results from follow-up observations of two Roche-lobe filling hot subdwarf binaries with white dwarf companions predicted to have accretion discs. ZTF J213056.71+442046.5 (ZTF J2130) with a 39-min period and ZTF J205515.98+465106.5 (ZTF J2055) with a 56-min period were both discovered as subdwarf binaries with light curves that could only be explained well by including an accretion disc in their models. We performed a detailed high-resolution spectral analysis, using Keck/ESI to search for possible accretion features for both objects. We also employed polarimetric analysis using the Nordic Optical Telescope (NOT) for ZTF J2130. We did not find any signatures of an accretion disc in either object, and placed upper limits on the flux contribution and variation in degree of polarization due to the disc. Owing to the short 39-min period and availability of photometric data over 6 yr for ZTF J2130, we conducted an extensive O − C timing analysis in an attempt to look for orbital decay due to gravitational wave radiation. No such decay was detected conclusively, and a few more years of data paired with precise and consistent timing measurements were deemed necessary to constrain $$\dot{P}$$ observationally.