Per/polyfluoroalkyl substances (PFASs) are persistent organic contaminants that are ubiquitous in surface waters. To date, their effects on aquatic systems, especially amphibians, are poorly understood. We examined the uptake and depuration of perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), and 6:2 fluorotelomer sulfonate (6:2 FTS) in northern leopard frog (Rana pipiens) tadpoles. Whole-body concentrations were examined every 10 d during constant aqueous exposure to targeted concentrations of 10, 100, and 1000 μg/L for 40 d and for 30 d during depuration. Effects of PFAS exposure on length and development were also examined. Rapid uptake led to steady state concentrations by 10 d for most exposures. PFOS accumulated to the highest levels with whole-body bioconcentration factor (BCF) values at 40 d ranging from 19.6 to 119.3. The remaining PFASs were not found to bioconcentrate (BCF < 1.0 at 40 d). Furthermore, some BCF values decreased during the exposure phase, suggesting dilution due to growth and/or changes in toxicokinetics over ontogeny. During depuration, half-lives ranged from 1.2 to 3.3 d for all compounds. All PFASs tended to induce developmental delays, though statistical significance was only seen for PFOS and PFHxS. These sublethal effects observed at environmentally relevant concentrations are concerning and merit further study.

Despite the extensive use of the neonicotinoid insecticide clothianidin, and its known toxicity to beneficial insects such as pollinators, little attention has been given to its fate under agricultural field conditions. The present study investigated the fate and toxicity of clothianidin applied every other year as a corn seed-coating at 2 different rates, 0.25 mg/seed and 0.50 mg/seed, in an agricultural field undergoing a corn-soybean annual rotation, and conservation tillage. Concentrations were measured in soil, surface runoff, infiltration, and groundwater from 2011 to 2013. Clothianidin was detected at low concentrations in soil and water throughout the 2-yr corn and soybean rotation. Low and no-tillage had little or no effect on clothianidin concentrations. Laboratory toxicity bioassays were performed on nontarget species, including Daphnia magna, Hyalella azteca, Chironomus dilutus, Pimephales promelas and Eisenia fetida. Risk quotients were calculated from clothianidin concentrations measured in the field and compared with the laboratory toxicity bioassay results to assess the environmental risk of the insecticide. The risk quotient was found to be lower than the level of concern for C. dilutus, which was the most sensitive species tested; therefore, no short-term environmental risk was expected for the species investigated in the present study.

Abstract. Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ONs) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ -terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ -terpinene oxidation by the nitrate radical (NO 3 ), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ -terpinene oxidation by NO 3 . Under dry conditions, the hydroxy nitrate yield = 4(+1/−3) %, total ON yield = 14(+3/−2) %, and SOA yield ≤ 10 % under atmospherically relevant particle mass loadings, similar to those for α-pinene + NO 3 . Using a chemical box model, we show that the measured concentrations of NO 2 and γ -terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO 3 chemistry. This suggests that NO 3 addition to either of the two internal double bonds of γ -terpinene primarily decomposes forming a relatively volatile keto-aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applying high-resolution liquid chromatography-mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental US and the Midwest, where polyolefinic monoterpene emissions are greatest.

Previous studies evaluating Vitamin B12 (VB12) with Ti(III)-citrate for potential use in in situ remediation of perfluorooctanesulfonate (PFOS) found that linear (L)-PFOS was unaltered. We explored if alternate reductants could overcome this limitation with a primary focus on nanoscale zerovalent zinc (nZn). Transformation over time with VB12-nZn was quantified at 22, 70, and 90 °C for PFOS, at 70 °C for perfluorohexanesulfonate (PFHxS), and VB12-nFe and VB12-Pd/nFe at 70 °C for PFOS. Only branched (br-) isomers were transformed generating F (no SO) and polyfluoroalkyl intermediates/products. The absence of L-PFOS transformation by VB12 appears to be due to the inability of L-perfluoroalkyl sulfonates to complex with VB12 and not an activation energy issue that can be overcome by stronger reductants/catalysts. At 90 °C, 95% of br-PFOS isomers were transformed within 5 days. Isomer-specific removal rates were positively correlated to the br-CF's proximity to the terminal CF. Br-PFHxS transformation was approximately two times slower with less defluorination than br-PFOS. C8/C7 and C6/C5 polyfluorinated sulfonates from br-PFOS and br-PFHxS, respectively, were identified as both intermediates and apparent dead-end products. Pathways included 4 F replaced by 2 H and a C═C bond, and serial F replacement by H with up to 12 F atoms removed from br-PFOS.

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