Fine particle pollution during megafires contains potentially toxic elements.

Wildfires that raged across Australia during the 2019-2020 'Black Summer' produced an enormous quantity of particulate matter (PM) pollution, with plumes that cloaked many urban centres and ecosystems along the eastern seaboard. This has motivated a need to understand the magnitude and nature of PM exposure, so that its impact on both built and natural environments can be more accurately assessed. Here we present the potentially toxic fingerprint of PM captured by building heating, ventilation, and air conditioning filters in Sydney, Australia during the peak of the Wildfires, and from ambient urban emissions one year later (Reference period). Atmospheric PM and meteorological monitoring data were also assessed to determine the magnitude and source of high PM exposure. The wildfires were a major source of PM pollution in Sydney, exceeding the national standards on 19 % of days between November-February. Wildfire particles were finer and more spherical compared to Reference PM, with count median diameters of 892.1 ± 23.1 versus 1484.8 ± 96.7 nm (mean ± standard error). On an equal-mass basis, differences in potentially toxic elements were predominantly due to higher SO42--S (median 20.4 vs 4.7 mg g-1) and NO3--N (2.4 vs 1.2 mg g-1) in Wildfire PM, and higher PO43--P (10.4 vs 1.4 mg g-1) in Reference PM. Concentrations of remaining elements were similar or lower than Reference PM, except for enrichments to F-, Cl-, dissolved Mn, and particulate Mn, Co and Sb. Fractional solubilities of trace elements were similar or lower than Reference PM, except for enhanced Hg (12.1 vs 1.0 %) and greater variability in Cd, Hg and Mn solubility, which displayed upper quartiles exceeding that of Reference PM. These findings contribute to our understanding of human and ecosystem exposures to the toxic components of mixed smoke plumes, especially in regions downwind of the source.

Fuelling phytoremediation: gasoline degradation by green wall systems-a case study.

The capacity for indoor plants including green wall systems to remove specific volatile organic compounds (VOCs) is well documented in the literature; however under realistic settings, indoor occupants are exposed to a complex mixture of harmful compounds sourced from various emission sources. Gasoline vapour is one of the key sources of these emissions, with several studies demonstrating that indoor occupants in areas surrounding gasoline stations or with residentially attached garages are exposed to far higher concentrations of harmful VOCs. Here we assess the potential of a commercial small passive green wall system, commercially named the 'LivePicture Go' from Ambius P/L, Australia, to drawdown VOCs that comprise gasoline vapour, including total VOC (TVOC) removal and specific removal of individual speciated VOCs over time. An 8-h TVOC removal efficiency of 42.45% was achieved, along with the complete removal of eicosane, 1,2,3-trimethyl-benzene, and hexadecane. Further, the green wall also effectively reduced concentrations of a range of harmful benzene derivatives and other VOCs. These results demonstrate the potential of botanical systems to simultaneously remove a wide variety of VOCs, although future research is needed to improve upon and ensure efficiency of these systems over time and within practical applications.

Predictability of thermal fluctuations influences functional traits of a cosmopolitan marine diatom.

Evolutionary theory predicts that organismal plasticity should evolve in environments that fluctuate regularly. However, in environments that fluctuate less predictably, plasticity may be constrained because environmental cues become less reliable for expressing the optimum phenotype. Here, we examine how the predictability of +5°C temperature fluctuations impacts the phenotype of the marine diatom Thalassiosira pseudonana. Thermal regimes were informed by temperatures experienced by microbes in an ocean simulation and featured regular or irregular temporal sequences of fluctuations that induced mild physiological stress. Physiological traits (growth, cell size, complexity and pigmentation) were quantified at the individual cell level using flow cytometry. Changes in cellular complexity emerged as the first impact of predictability after only 8-11 days, followed by deleterious impacts on growth on days 13-16. Specifically, cells with a history of irregular fluctuation exposure exhibited a 50% reduction in growth compared with the stable reference environment, while growth was 3-18 times higher when fluctuations were regular. We observed no evidence of heat hardening (increasingly positive growth) with recurrent fluctuations. This study demonstrates that unpredictable temperature fluctuations impact this cosmopolitan diatom under ecologically relevant time frames, suggesting shifts in environmental stochasticity under a changing climate could have widespread consequences among ocean primary producers.

The botanical biofiltration of volatile organic compounds and particulate matter derived from cigarette smoke.

Despite the growing use of control measures, environmental tobacco smoke (ETS) remains a significant pollutant source in indoor air in many areas of the world. Current control methods for reducing ETS exposure are inadequate to protect public health in environments where cigarettes are smoked. An alternative solution is botanical biofiltration which has previously been shown to lower concentrations of volatile organic compounds (VOCs) and particulate matter (PM) from a range of polluted air streams. This study is the first to assess the potential of a botanical biofilter with the species Spathiphyllum wallisii (Peace Lily) for the removal of cigarette-derived VOCs and all size fractions of PM. Single pass removal efficiencies of 43.26% for total VOCs and 34.37% for total suspended particles were achieved. The botanical biofilter reduced the concentrations of a range of harmful ETS chemicals including nicotine, limonene, and toluene. Evaluation of the re-emission of ETS constituents filtered by the botanical biofilter revealed no particle resuspension or off gassing. The results demonstrate the potential of botanical biofilters to reduce public ETS exposure, although further research is needed to improve upon and ensure the efficiency of these systems for practical applications.