• 关键词：溶解有机物  落叶  光降解  微生物降解  铅

• 基金项目：福建省自然科学基金项目（No.2021J01626）；国家自然科学基金（No.41606094）

• 刘芳
• 福州大学环境与安全工程学院，福州 350116

• 陈琳崴
• 福州大学环境与安全工程学院，福州 350116

• 庄婉娥
• 福建农林大学生命科学学院，福州 350002

• 杨丽阳
• 福州大学环境与安全工程学院，福州 350116

• 摘要：溶解有机物（DOM）是决定水环境中铅（Pb）的形态、环境行为和生态风险的重要因子.然而，落叶DOM与Pb（II）络合作用的调控机制尚不清楚.光和微生物降解是调控DOM含量、组成与活性的两个关键过程.本研究运用降解培养实验、光谱学表征和荧光猝灭滴定，考察光和微生物降解单独作用和共同作用对芦苇落叶DOM的改造及其对DOM与Pb（II）相互作用的影响.激发-发射三维荧光光谱-平行因子分析共识别出4个类腐殖质组分（C1~C4）和1个类蛋白质组分（C5）.类腐殖质组分更容易被光降解，类蛋白质组分则被微生物优先利用，光降解在短期的光-微生物降解过程中起主导作用.对于原始落叶DOM，Pb（II）主要与类腐殖质组分C1、C2和C4络合，C3组分只在光-微生物降解后的样品呈现显著荧光猝灭，类蛋白质组分C5在光和光-微生物降解后开始参与络合.类腐殖质C1与Pb（II）络合的条件稳定常数logK_M在光降解后升高而在光-微生物降解后下降，C2和C4的logK_M值经过各降解过程后均升高.降解后这3个组分参与络合的比例f和络合容量F_max·f均显著降低，且光降解的影响显著高于微生物降解.这些结果表明，光降解和微生物降解对DOM丰度、组成和结构的改造将显著影响其与金属离子的络合稳定性和络合容量.

• Abstract：Dissolved organic matter （DOM） is important for determining the speciation， environmental behavior， and ecological risk of lead （Pb） in the aquatic environment. However， the underlying mechanism for the complexation of leaf litter DOM with Pb（II） remains unclear. Photochemical and microbial degradation are two key processes in determining the level， composition， and reactivity of dissolved organic matter （DOM）. This study examined the effects of photo- and microbial degradation on the transformation of DOM released from reed leaf litter and the interaction between DOM and Pb（II）， by laboratory incubation， spectroscopic characterization， and fluorescence quenching titration. Four humic-like components （C1~C4） and one protein-like component （C5） were identified with fluorescence excitation-emission matrices-parallel factor analysis. Humic-like components were more susceptible to photo-degradation， while the protein-like component was preferentially utilized by microbes. Photo-degradation played a dominant role in the short-term photo-microbial degradation. For the original leaf litter DOM， Pb（II） was mainly complexed with humic-like components （C1， C2， and C4）， while C3 showed significant fluorescence quenching only after photo-microbial degradation. The protein-like C5 complexed with Pb（II） after photo- and photo-microbial degradation. The conditional stability constant logK_M of humic-like C1 increased after photo-degradation and decreased after photo-microbial degradation. The logK_M of C2 and C4 both increased after degradation. The complexation fraction f and the complexing capacity F_max·f of C1， C2， and C4 reduced after all degradation， which was more significant after photo-degradation than after microbial degradation. These results demonstrated that the changes of DOM abundance， composition， and structure by photo- and microbial degradation would strongly affect its complexation stability and complexation capacity with metal ions.

• Key words：dissolved organic matter  leaf litter  photo-degradation  microbial degradation  lead

• 
  摘要点击次数： 193 全文下载次数： 270