Organic compounds in valley fogwater in North and Mount Lebanon during COVID-19 period

Caltech Active Strand Cloudwater collectors are used to collect valley fog samples from Mount and North-Lebanon during 2021 for the speciation of organic matter for the first time ever. Numerous compounds including pesticides, phenols, acids, and persistent organic pollutants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs) have been identified in fogwater samples. They are extracted using the liquid-liquid extraction performed on the XTR chromabond columns. The highest contribution to the total organic fraction refers to phenols and acids (around 77 %) due to their better water solubility than others inducing a good affinity to the aqueous phase of fogwater droplets. The lowest contribution refers to the hydrophobic families accounting together for <5 % of the total fraction. Pearson analysis is employed in this study to check correlations between some variables. PAHs are found to be originated from combustion and vehicle exhaust and PCBs are found to be highly correlated with PAHs. Phenols and acids are highly associated with PAHs and PCBs as well as with sulfate and heavy metals (manganese and nickel). This shows that their sources can be either atmospheric oxidation or vehicle exhaust. Pesticides are found to be highly correlated with each other which suggests their simultaneous applications. Despite all, more research is still needed to have a bigger and more reliable data to adopt the beneficial effect of fogwater as an alternative for fresh water at least for the Lebanese agriculture.