Volatile organic compounds (VOCs) are produced by macroalgae in response to environmental stresses. A novel approach using Solid Phase Microextraction (SPME) was used to quantify the production of several VOCs from eight common intertidal algal species from the UK (Ascophyllum nodosum (Linnaeus) Le Jolis, Fucus vesiculosus (Linnaeus), Fucus serratus (Linnaeus), Laminaria digitata (Hudson) Lamouroux, Ulva lactuca (Linnaeus), Ulva intestinalis (Linnaeus), formerly known as Enteromorpha, Palmariapalmata (Linnaeus) Kuntze and Griffithsiaflosculosa (J. Ellis) Batters). The volatile compounds included halogenated, sulphur containing, aldehydes, non-methane hydrocarbons (NMHC) and oxygenated species. Overall, the production of VOCs by these algae was not considerably different under illumination or in darkness; this suggests that the VOC production occurs during both algae photosynthesis and in other metabolic processes such as respiration or osmoregulation. Desiccation played an important role in the production of VOCs with greater production by macroalgae after desiccation. This production was related to the alga's normal position within the intertidal zone; there was a lower production of VOCs for species growing near the high water mark and a greater production for algae taken from the low tide position. There were also species differences in the VOC profiles and quantities released. For example, chlorinated and oxygenated compounds were principally released by the brown alga Ascophyllum nodosum, while green algae such as Ulva lactuca and Ulva intestinalis released greater amounts of brominated, sulphur containing compounds, aldehydes and non-methane hydrocarbons than the other algae tested. Thekelps (e.g. Laminaria digitata) had the greatest release of iodinated compounds such as diiodomethane. These processes make significant contributions to the VOCs in seawater and, by transfer to the atmosphere, in the coastal atmosphere.

The occurrence of airborne particulate matter has been flagged as “of concern” in several megacities, especially in Asia. Selected Chilean regions have similar problems as wood burning is the major source of heating in homes. This concern has led to mitigation measures restricting the burning of wood at periods when the particulate matter smaller than 2.5 μm (PM_2.5) concentrations are predicted to be high. This work investigates the linkage between indoor and outdoor particle concentrations, determines their source through the polyaromatic hydrocarbon (PAH) signature and investigates the efficacy of the current management practice of burning restrictions. The PM_2.5 fraction was collected at 12 different properties with coincident indoor and outdoor sampling using a low-volume active sampler for 24 hours. Indoor concentrations of PM_2.5 ranged from 6 to 194 μg m⁻³ with a mean of 72 μg m⁻³ and corresponding outdoor concentrations ranged from 5 to 367 μg m⁻³ with a mean of 85 μg m⁻³ over the winter periods of 2014 and 2015; the Chilean national permitted maximum in outdoor air is 50 μg m⁻³ in 24 hours. Higher concentrations were measured when the outdoor air temperature was lower. The PAHs were analysed on the PM_2.5 fraction; the indoor concentrations ranged from 2 to 291 ng m⁻³ with a mean of 51 ng m⁻³ compared to an outdoor concentration between 3 and 365 ng m⁻³ with a mean of 71 ng m⁻³. Multivariate statistical analysis of the PAH profiles using principal components analysis (PCA) and polytopic vector analysis (PVA) identified wood burning, static and mobile diesel emissions and kerosene combustion as the major contributors to the particulate matter. When converted to toxicity equivalents (BaP-TEQ), the highest toxicity arising from PAHs in the indoor air was associated with a property that used a “leaky” combined wood stove and heater and also used a wood-fired brazier for local heating. In outdoor air, there was a relationship between the housing density and the BaP-TEQ, such that denser housing had higher BaP-TEQ values. The restrictions in wood burning on selected days may have had a measureable effect on the PM_2.5 concentrations in that region but the effects were small and only present for the day of the restriction.

Airborne particulate matter (PM_2.5) are known environmental cotaminants. Nevertheless, it is not only the size of particulate matter that influences human health, but also its chemical composition. The chemical composition of the PAH suite in PM_2.5 may be indicative of the source materials, typically combustion products. In this study, particulate matter (PM_2.5) was collected using portable air samplers during all of 2013 and 2014 at five locations of the Los Rios Region, Valdivia, Chile. The quantity of PM_2.5 collected was measured using gravimetric methods. Solvent extracts were analyzed for associated PAHs by means of GC-MS techniques. The concentrations of PM_2.5 for all locations ranged from 2.8 to 386 µg/m³ for the autumn/winter periods and from 1.1 to 315 µg/m³ for the spring/summer periods. The mean concentrations of PM_2.5 ranged from 11.9 to 112 µg/m³ in summer for all sites. The concentrations of PAHs for all locations ranged from 2.8 to 115 ng/m³ for the autumn/winter periods and from 0.3 to 32 ng/m³ for the spring/summer periods. To determine the possible sources of PM_2.5, cross-plots, PCA, and PVA analyses were performed. The results demonstrated that biomass burning was the dominant source of PM_2.5 at all locations during autumn/winter periods with PAHs having four to six rings; during the spring/summer periods, PAHs with two to three rings were more abundant and were related to petrogenic sources. The sources of PM_2.5 in the different studied areas were similar and were related to season rather than to geography. Analysis of meteorological data for the region demonstrated that the background summer PM_2.5 for the years studied was ∼8 µg/m³ while when temperatures decreased below 15°C, there was an exponential increase in the concentration of particles in the air.