Comparison between the spectra of HOA and fulvic acids (FA) indicated that both contained a large amount of carboxylic groups and that the former contained more carbohydrates and less aromaticity.

• 疏水酸性组分 (HOA)的结构特征相似于土壤FA ,含有大量羧基 ,但与FA相比芳香族物质减少 ,碳水化合物增多 ;