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An in situ exposure and effects bioassay system was developed for assessing the toxicity of oil spills to aquatic organisms. The assessment tool combines components of 2 previously developed systems, the sediment ecotoxicity assessment ring (SEA Ring) and the drifting particle simulator. The integrated drifting exposure and effects assessment ring (DEEAR) is comprised of a Global Positioning System (GPS) float, a drifter drogue, the SEA Ring, and the Cyclops‐7 fluorescent sensor. Polyethylene passive sampling devices (PED) were mounted for an additional means to characterize water quality conditions and exposures. The DEEAR is optimized for evaluating oil exposure and toxicity in the shallow surface mixing layer of marine waters. A short‐term preliminary test was conducted in San Diego, California, USA, to verify the operation of the GPS tracking, the iridium communications, and the integrated SEA Ring exposure system. Further, a proof‐of‐concept demonstration was conducted offshore in the Santa Barbara Channel, where natural oil seeps produce surface slicks and sheens. Two DEEAR units were deployed for 24 h—one within the oil slick and one in an area outside observable slicks. An aerial drone provided tracking of the surface oil and optimal sites for deployment. The DEEAR proof‐of‐concept demonstrated integrated real‐time tracking and characterization of oil exposures by grab samples, PED, and fluorescent sensors. Oil exposures were directly linked to toxic responses in fish and mysids. This novel integrated system shows promise for use in a variety of aquatic sites to more accurately determine in situ oil exposure and toxicity. Environ Toxicol Chem 2021;40:1452–1462. © 2021 SETAC [ABSTRACT FROM AUTHOR]

In many cases, stormwater compliance monitoring is labor intensive, expensive, and largely unsuccessful in providing the data needed to support stormwater management goals. To help address these issues, diffusive gradients in thin film (DGTs), time-integrative passive samplers for metals, were evaluated to monitor copper in stormwater runoff. DGTs were co-located with traditional autosamplers within the stormwater conveyance systems at Naval Base San Diego (NBSD) to provide a direct comparison with composite sampling. DGTs were exposed in the laboratory to flow-averaged composite samples from NBSD stormwater conveyance systems. These experiments showed increasing uptake over time (range = 1.5–24 h) for copper, with positive, linear correlations (r2 > 0.980) between exposure duration and copper mass accumulated. However, it appears that the corresponding calculations of the DGT-labile fraction (C DGT) relative to the dissolved fraction fluctuated across the different exposure durations. In general, trends observed for C DGT measurements from the field were consistent with trends in the lab DGT exposures and traditional dissolved metal measurements from composite samples. Finally, time-weighted average copper concentrations from DGTs deployed for the first and second phases of storm events were within 30% of measurements from DGTs that were deployed for the entire storm event in the same stormwater vault. Cumulatively, these results show promise for continuous monitoring with DGTs as an approach that produces data more representative of exposure to the receiving environment during episodic events than data from traditional grab or composite chemistry sampling, and can represent significant cost savings. • DGT data compared well with more resource intensive autosampler derived data. • DGTs consistently measured labile copper in stormwater with exposure durations ≥ 6 h • DGTs measurements of labile copper were consistent when deployed in stormwater vaults. • Simplicity of DGT makes it a logical alternative to traditional stormwater sampling. [ABSTRACT FROM AUTHOR]