我国南方桉树人工林区水体泛黑物质分子组成及形成机理OA北大核心CSTPCD

Black water frequently occurs in reservoirs within Eucalyptus artificial forest regions of southern China during the autumn and winter seasons.Previous studies have identified the primary cause as the complex formed by the reaction between substances like tannic acid in Eucalyptus leaves and metal ions,particularly iron ions.However,potential organic matter precursors forming these complexes in Eucalyptus leaves remains unclear.The molecular composition-based mechanism behind water blackening in Eu-calyptus artificial forest reservoirs is not yet clear.This study employed Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)to analyze the molecular composition of soluble organic compounds in Eucalyptus leaf soaking solutions and reser-voirs in typical Eucalyptus forest areas(Jinwo and Tianbao Reservoirs).The results revealed that the Eucalyptus leaf soaking solu-tion predominantly comprised polyphenolic compounds and their polymeric derivatives,primarily based on phenolic and gallic acids,with ellagic acid(C14H6O8)being the most prevalent compound.Tannic acid concentration in winter reservoir water was higher than that in summer,with higher concentration observed in surface water compared to bottom water.This suggested that the substantial release of aromatic polyphenols from fallen Eucalyptus leaves during autumn and winter had a large contribution to black water.Subsequent experiments demonstrated that ellagic acid,pyrogallol,and gallic acid undergo complex reactions with iron ions,resulting in black precipitates.These outcomes collectively highlighted that aromatic polyphenols dissolved from Eucalyptus leaves were the primary factor causing black water.The study proposed a molecular composition-based mechanism for the formation of black water in Eucalyptus artificial forest area reservoirs,and offered crucial insights for effective management and ensuring the safety of drinking water in such reservoirs.