Nature and origin of soluble lipids shed into the soil by rainwater leaching a forest cover of Pinus maritima sp.

We have studied the ability of rainwater leaching a pine (Pinus maritima sp.) forest cover to solubilize lipid components. The nature and origin of straight-chain hydrocarbons, alcohols and monoacids shed into the soil by rainwater was determined. Rainwater falling from branches and pine needles (RF) and rainwater running down the tree trunks (RR) were collected separately. The compounds were quantified and identified by gas chromatography used alone or coupled with gas chromatography. The dominant fraction of soluble lipids was aliphatic alcohols (alkanols) in RR and monoacids in RF. The concentration in water of total hydrocarbons and of total alkanols was the greatest in winter. In contrast, the proportion of alcohols with a number of carbon atoms <C20 in total alcohols and of branched monoacids in total monoacids were the highest in summer. Hydrocarbons were almost solely of bacterial origin but alcohols and monoacids showed components both of bacterial and of higher-plant origin, the latter being more abundant in RR than in RF.