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Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), key isoprene oxidation products, with inorganic sulfate aerosol yields substantial amounts of secondary organic aerosol (SOA) through the formation of organosulfur compounds. The extent and implications of inorganic-to-organic sulfate conversion, however, are unknown. In this article, we demonstrate that extensive consumption of inorganic sulfate occurs, which increases with the IEPOX-to-inorganic sulfate concentration ratio (IEPOX/Sulfinorg), as determined by laboratory measurements. Characterization of the total sulfur aerosol observed at Look Rock, Tennessee, from 2007 to 2016 shows that organosulfur mass fractions will likely continue to increase with ongoing declines in anthropogenic Sulfinorg, consistent with our laboratory findings. We further demonstrate that organosulfur compounds greatly modify critical aerosol properties, such as acidity, morphology, viscosity, and phase state. These new mechanistic insights demonstrate that changes in SO2 emissions, especially in isoprene-dominated environments, will significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX/Sulfinorg will play an important role in understanding the historical climate and determining future impacts of biogenic SOA on the global climate and air quality.

Optimal egg size theory implies that female organisms balance between fecundity and individual offspring investment according to their environment. Past interspecific studies suggest that fishes in large marine systems generally produce smaller eggs than those in small freshwater systems. We tested whether intraspecific egg size variation reflected a similar pattern by comparing egg size among yellow perch (Perca flavescens) populations inhabiting a range of system sizes. In 2018, 2019, and 2023, we collected yellow perch egg samples from 12 locations in systems ranging in surface area from 37 to 5,390,492 ha. First, we found that egg diameter significantly increased with maternal total length in five of eight individually tested populations. After accounting for these maternal effects, we found a significant interaction, where females inhabiting larger lakes, such as the main basins of Lakes Erie and Michigan, produced smaller eggs than those in smaller inland lakes, and the greatest differences were demonstrated among females of greater total length. This egg size variation in the largest females is consistent with interspecific egg size comparisons between marine and freshwater fishes. However, by examining a single species across vastly different environments, we were able to support theoretical expectations that maternal investment in offspring should vary with environmental conditions controlling early‐life resource acquisition and competition. [ABSTRACT FROM AUTHOR]

In the southeastern US, substantial emissions of isoprene from deciduous trees undergo atmospheric oxidation to form secondary organic aerosol (SOA) that contributes to fine particulate matter (PM2.5). Laboratory studies have revealed that anthropogenic pollutants, such as sulfur dioxide (SO2), oxides of nitrogen (NO x ), and aerosol acidity, can enhance SOA formation from the hydroxyl radical (OH)-initiated oxidation of isoprene; however, the mechanisms by which specific pollutants enhance isoprene SOA in ambient PM2.5 remain unclear. As one aspect of an investigation to examine how anthropogenic pollutants influence isoprene-derived SOA formation, high-volume PM2.5 filter samples were collected at the Birmingham, Alabama (BHM), ground site during the 2013 Southern Oxidant and Aerosol Study (SOAS). Sample extracts were analyzed by gas chromatography-electron ionization-mass spectrometry (GC/EI-MS) with prior trimethylsilylation and ultra performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) to identify known isoprene SOA tracers. Tracers quantified using both surrogate and authentic standards were compared with collocated gas- and particle-phase data as well as meteorological data provided by the Southeastern Aerosol Research and Characterization (SEARCH) network to assess the impact of anthropogenic pollution on isoprene-derived SOA formation. Results of this study reveal that isoprene-derived SOA tracers contribute a substantial mass fraction of organic matter (OM) (~ 7 to ~ 20 %). Isoprene-derived SOA tracers correlated with sulfate ( SO42- ) (r2 = 0.34, n = 117) but not with NO x . Moderate correlations between methacrylic acid epoxide and hydroxymethyl-methyl-α-lactone (together abbreviated MAE/HMML)-derived SOA tracers with nitrate radical production (P[NO3]) (r2 = 0.57, n = 40) were observed during nighttime, suggesting a potential role of the NO3 radical in forming this SOA type. However, the nighttime correlation of these tracers with nitrogen dioxide (NO2) (r2 = 0.26, n = 40) was weaker. Ozone (O3) correlated strongly with MAE/HMML-derived tracers (r2 = 0.72, n = 30) and moderately with 2-methyltetrols (r2 = 0.34, n = 15) during daytime only, suggesting that a fraction of SOA formation could occur from isoprene ozonolysis in urban areas. No correlation was observed between aerosol pH and isoprene-derived SOA. Lack of correlation between aerosol acidity and isoprene-derived SOA is consistent with the observation that acidity is not a limiting factor for isoprene SOA formation at the BHM site as aerosols were acidic enough to promote multiphase chemistry of isoprene-derived epoxides throughout the duration of the study. All in all, these results confirm previous studies suggesting that anthropogenic pollutants enhance isoprene-derived SOA formation.

Amine-based postcombustion CO2 capture (PCCC) is a promising technique for reducing CO2 emissions from fossil fuel burning plants. A concern of the technique, however, is the emission of amines and their degradation byproducts. To assess the environmental risk of this technique, standardized stack sampling and analytical methods are needed. Here we report on the development of an integrated approach that centers on the application of a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) for characterizing amines and PCCC-relevant species. Molecular characterization is achieved via ion chromatography (IC) and electrospray ionization high-resolution mass spectrometry (ESI-MS). The method has been optimized, particularly, by decreasing the AMS vaporizer temperature, to gain quantitative information on the elemental composition and major nitrogen-containing species in laboratory-degraded amine solvents commonly tested for PCCC applications, including ethanolamine (MEA), methyldiethanolamine (MDEA), and piperazine (PIP). The AMS-derived nitrogen-to-carbon (N/C) ratios for the degraded solvent and product mixtures agree well with the results from a total organic carbon and total nitrogen (TOC/TN) analyzer. In addition, marker ions identified in the AMS spectra are used to estimate the mass contributions of individual species. Overall, our results indicate that this new approach is suitable for characterizing PCCC-related mixtures as well as organic nitrogen species in other sample types. As an online instrument, AMS can be used for both real-time characterization of emissions from operating PCCC plants and ambient particles in the vicinity of the facilities.

Stock reproductive potential informs population dynamics and response to harvest. Indices of body condition, like relative weight ([W.sub.r]), may indicate individual energetic state and provide a mechanistic link between spawning stock traits and recruitment. We tested for relationships among [W.sub.r] of three female size classes (381-456, 457-557, and [greater than or equal to] 558 mm total length), reproductive traits, and age-0 recruitment using data from 92 walleye (Sander vitreus) populations in the Ceded Territory of Wisconsin during 1989-2015 and a lake-specific time series from Escanaba Lake, Wisconsin, during 1958-2014. In Escanaba Lake, [W.sub.r] was positively related to maturation in small females and was positively related to fecundity and gonadosomatic index in intermediate fish. Among and within populations, [W.sub.r] demonstrated compensatory density dependence and positive relationships with growing degree-days. Recruitment was positively related to large female [W.sub.r] variation across lakes and negatively related to small female [W.sub.r] variation in Escanaba Lake. Improving the condition of large female walleye may promote recruitment, and [W.sub.r] may serve as an accessible metric of reproductive potential in walleye stock-recruit analyses. Le potentiel reproducteur des stocks fournit de l'information sur la dynamique des populations et les reactions a la peche. Des indices d'embonpoint, comme l'indice de masse relative ([W.sub.r]), pourraient refleter l'etat energetique des individus et constituer un lien mecaniste entre des caracteres du stock reproducteur et le recrutement. Nous avons verifie la presence de liens entre le [W.sub.r] de trois classes de taille de femelles (longueur totale : 381-456, 457-557 et [greater than or equal to] 558 mm), des caracteres associes a la reproduction et le recrutement d'individus de moins d'un an en utilisant des donnees de 92 populations de dore jaune (Sander vitreus) dans le Territoire cede du Wisconsin recueillies de 1989 a 2015, ainsi qu'une serie chronologique pour le lac Escanaba (Wisconsin) allant de 1958 a 2014. Dans ce lac, le [W.sub.r] est positivement relie a la maturation chez les petites femelles et a la fecondite et l'indice gonadosomatique chez les poissons de taille intermediaire. Au sein de populations et entre elles, le [W.sub.r] presente une dependance compensatoire sur la densite et des relations positives avec le nombre de jours de croissance. Le recrutement est positivement relie aux variations du [W.sub.r] des grosses femelles dans tous les lacs et negativement relie aux variations du [W.sub.r] des petites femelles dans le lac Escanaba. L'amelioration de l'embonpoint de gros dores jaunes femelles pourrait favoriser le recrutement, et le [W.sub.r] pourrait constituer une mesure facilement accessible du potentiel reproducteur pour les analyses du recrutement au stock pour le dore jaune. [Traduit par la Redaction], Introduction Variation in the reproductive potential of fish stocks can have important influences on population growth, recruitment dynamics, and responses to environmental change (Marshall et al. 1999; Dorner et al. [...]

Harvest in walleye Sander vitreus fisheries is size‐selective and could influence phenotypic traits of spawners; however, contributions of individual spawners to recruitment are unknown. We used parentage analyses using single nucleotide polymorphisms to test whether parental traits were related to the probability of offspring survival in Escanaba Lake, Wisconsin. From 2017 to 2020, 1339 adults and 1138 juveniles were genotyped and 66% of the offspring were assigned to at least one parent. Logistic regression indicated the probability of reproductive success (survival of age‐0 to first fall) was positively (but weakly) related to total length and growth rate in females, but not age. No traits analyzed were related to reproductive success for males. Our analysis identified the model with the predictors' growth rate and year for females and the models with year and age and year for males as the most likely models to explain variation in reproductive success. Our findings indicate that interannual variation (i.e., environmental conditions) likely plays a key role in determining the probability of reproductive success in this population and provide limited support that female age, length, and growth rate influence recruitment. [ABSTRACT FROM AUTHOR]

In response to declines in coarse woody habitat (CWH) and fish productivity in natural lakes and reservoirs, agencies and stakeholders have used woody and artificial habitat enhancements to slow or reverse the effects of habitat loss from aging or shoreline development. Given that natural lakes and reservoirs differ in physical and biological conditions that could influence habitat enhancement outcomes, a framework is needed to guide management expectations for CWH replacement under different ecosystem contexts. We review ecosystem contexts that influence the effects of structural habitat enhancements in natural lakes and reservoirs, use preliminary results from case studies in a natural lake in Wisconsin and two reservoirs in Illinois to illustrate the importance of these contexts, and provide management recommendations for habitat deployments that consider physical and biological ecosystem characteristics. Because of their influence on trophic transfer efficiency, trophic status and turbidity are important contexts for habitat enhancements in natural lakes and reservoirs. Habitat enhancements to large reservoirs must also contend with high nutrient loading, water level fluctuations, and longitudinal gradients in physical and biological conditions. Preliminary results from the Wisconsin experiment illustrated the importance of the recipient fish community, with rates of response to the structural enhancement varying among fish species. The Illinois case studies demonstrated how the magnitude of change (i.e., effect size) after habitat enhancement can differ (1) between CWH additions to an oligotrophic natural lake and a eutrophic, turbid reservoir and (2) by longitudinal position of artificial habitat within a large reservoir. The functions or ecosystem services of CWH targeted for rehabilitation provide guidance as to which ecosystem features will shape the strength, direction, and duration of response. Future whole‐ecosystem manipulations are needed across a wider range of environmental contexts and fish productivity responses, and the strength of productivity increases should be compared to increased harvest efficiency. [ABSTRACT FROM AUTHOR]

ABSTRACT Lawn and garden equipment are a significant source of emissions of volatile organic compounds (VOCs) and other pollutants in suburban and urban areas. Emission estimates for this source category [...]

Knowledge of density‐dependent responses of fish populations to exploitation is important for the sustainable management of fisheries and in structuring fish populations to meet angler desires. To better understand the density‐dependent responses of Walleye Sander vitreus to exploitation, we conducted a 10‐year, 50% annual exploitation experiment on Sherman Lake, Wisconsin, during 2007–2016. In the following order, annual exploitation goals were met through liberalized recreational angling regulations, tribal spearfishing, and physical removals (if necessary). Response variables included total and sex‐specific adult density, age‐0 and age‐1 relative abundance, age‐0 to age‐1 survival, length at maturity, individual growth, and population size structure. To control for environmental and interannual influences on adult density and recruitment, unexploited Escanaba Lake, Wisconsin, was used as a reference system. Total and sex‐specific adult density and age‐0 relative abundance did not differ between Sherman and Escanaba lakes. Age‐1 relative abundance was significantly higher and more variable under elevated exploitation compared with the reference lake. Age‐0 to age‐1 survival significantly increased between pretreatment and elevated‐exploitation time periods. Sex‐specific length at maturity significantly declined between pretreatment and elevated‐exploitation time periods. Mean juvenile length at age increased, male asymptotic length declined, and the proportional size distribution of quality‐sized Walleye declined between pretreatment and elevated‐exploitation time periods. Our results suggest that compensatory age‐0 to age‐1 survival and declines in length at maturity interacted to offset elevated‐exploitation effects on adult density. Likewise, density‐dependent growth responses were most evident in juveniles. Although the Sherman Lake Walleye population appeared resilient to elevated exploitation, we caution that this level of long‐term exploitation is likely not sustainable for most Walleye populations due to the findings of previous exploitation studies and observations of depensatory recruitment dynamics in Walleye. [ABSTRACT FROM AUTHOR]