Soil and leaf litter are significant global sources of small oxidized volatile organic compounds, VOCs (e.g., methanol and acetaldehyde). They may also be significant sources of larger VOCs that could act as precursors to secondary organic aerosol (SOA) formation. To investigate this, soil and leaf litter samples were collected from the University of Idaho Experimental Forest and transported to the laboratory. There, the VOC emissions were characterized and used to drive SOA formation via dark, ozone-initiated reactions. Monoterpenes dominated the emission profile with emission rates as high as 228 μg-C m–2 h–1. The composition of the SOA produced was similar to biogenic SOA formed from oxidation of ponderosa pine emissions and α-pinene. Measured soil and litter monoterpene emission rates were compared with modeled canopy emissions. Results suggest surface soil and litter monoterpene emissions could range from 12 to 136% of canopy emissions in spring and fall. Thus, emissions from leaf litter may potentially extend the biogenic emissions season, contributing to significant organic aerosol formation in the spring and fall when reduced solar radiation and temperatures reduce emissions from living vegetation.

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Using microalgae to capture CO2 from flue gas is an ideal way to reduce CO2 emission, but this is challenged by the high cost of carbon capture and transportation. To address this problem, a bicarbonate-based integrated carbon capture and algae production system (BICCAPS) has been proposed, in which bicarbonate is used for algae culture, and the regenerated carbonate from this process can be used to capture more CO2. High-concentration bicarbonate is obligate for the BICCAPS. Thus, different strains of microalgae and cyanobacteria were tested in this study for their capability to grow in high-concentration NaHCO3. The highest NaHCO3 concentrations they are tolerant to were determined as 0.30 M for Synechocystis sp. PCC6803, 0.60 M for Cyanothece sp., 0.10 M for Chlorella sorokiniana, 0.60 M for Dunaliella salina, and 0.30 M for Dunaliella viridis and Dunaliella primolecta. In further study, biomass production from culture of D. primolecta in an Erlenmeyer flask with either 0.30 M NaHCO3 or 2 % CO2 bubbling was compared, and no significant difference was detected. This indicates BICCAPS can reach the same biomass productivity as regular CO2 bubbling culture, and it is promising for future application.

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Activated persulfate is a commonly used oxidant source used for in situ chemical oxidation (ISCO) for remediation of subsurface contamination. Surfactants are sometimes used in ISCO to desorb contaminants and dissolve nonaqueous phase liquids (NAPLs). The potential activation of persulfate by such surfactants was investigated, and the reactive oxygen species generated by persulfate in the presence of anionic, nonionic, and cationic surfactants were determined. Twenty surfactants were screened; most activated persulfate to generate reductants + nucleophiles at acidic and basic pH. The most reactive anionic, nonionic, and cationic surfactants (Lankropol 4500, polyethylene glycol 400, and Ethoduomeen T/25) were investigated in more detail. All three surfactants activated persulfate; however, the cationic surfactant showed the most potential for persulfate activation with high fluxes of hydroxyl radical and reductants + nucleophiles. The results of this research demonstrate that surfactants added to ISCO systems often activate persulfate to generate reductants at both acidic and basic pH, and hydroxyl radical at basic pH. These findings provide a new paradigm for persulfate activation in surfactant in situ chemical oxidation (SISCO) systems; pH regimes >11 may not be necessary for persulfate activation resulting in cost savings and potentially more effective activation of persulfate.