Biomass burning emits large amounts of phenols, which can partition into cloud/fog drops and aerosol liquid water (ALW) and react to form aqueous secondary organic aerosol (aqSOA). Triplet excited states of organic compounds ( 3 C*) are likely oxidants, but there are no rate constants with highly substituted phenols that have high Henry's law constants (K H ) and are likely important in ALW. To address this gap, we investigated the kinetics of six highly substituted phenols with the triplet excited state of 3,4-dimethoxybenzaldehyde. Second-order rate constants at pH 2 are all fast, (2.6−4.6) × 10 9 M −1 s −1 , while values at pH 5 are 2−5 times smaller. Rate constants are reasonably described by a quantitative structure−activity relationship with phenol oxidation potentials, allowing rate constants of other phenols to be predicted. Triplet-phenol kinetics are unaffected by ammonium sulfate, sodium chloride, galactose (a biomassburning sugar), or Fe(III). In contrast, ammonium nitrate increases the rate of phenol loss by making hydroxyl radicals, while Cu(II) inhibits phenol decay. Mass yields of aqueous SOA from triplet reactions are large and range from 59 to 99%. Calculations using our data along with previous oxidant measurements indicate that phenols with high K H can be an important source of aqSOA in ALW, with 3 C* typically the dominant oxidant.

This study aims to evaluate the size of the sedimentary carbon sink in the coupling with environmental conditions in a mangrove planted in an abandoned salt pan in Can Gio Mangrove Biosphere Reserve. Sediment samples were collected at four sites chosen based on their dominant plant species. Sediment temperature, pH, salinity, humidity and wet bulk density were measured in field, while the nutrients (NH4+, PO43-) and organic carbon (Corg) concentrations were determined in the laboratory. The results showed that humidity, salinity and bulk density were strongly correlated with Corg concentrations. The amounts of organic carbon stored in the sediments in the dry and wet season were 380 MgC.ha-1 and 552 MgC.ha-1 respectively. Sediment humidity and salinity were the primary factors governing the size of the sedimentary carbon sink. The concentrations of organic carbon and ammonium were influenced by an allochthonous source entering the study area via the tidal creek network.