母环及烷基取代多环芳烃在红树林湿地中的环境行为及界面过程机制

Abstract: On the basis of our previous grants from Natural Science Foundation of China (NSFC), we will continue the study on typical parent PAHs (P-PAHs) with the addition of alkylated PAHs (A-PAHs). The present study mainly focus on the establishment of online and in situ analytical methods for the simultaneous measurement of P-PAHs, A-PAHs and their metabolites by using synchronous fluorimetry, laser-induced time-resolved fluorescence. Firstly, a new microscopic fluorescence system will be set up for environmental science study, which will be used to study adsorption and desorption behaviors of target compounds in micro-structure of sediment and the mechanisms. Besides, GC/GC-MS is selected to investigate the concentration and distribution of target compounds in water and sediments of mangrove wetlands, as well as source identification. The present study will combine ecological simulated study in lab and in situ study in real environment to investigate the environmental behaviors of target compounds in mangrove wetlands, and the interface process and mechanisms. The results of this study will 1) reveal exchange and transform patterns of target compounds in water/sediment/root interface and the related mechanisms; 2) gain insight into effects of micro-structure and characteristics of sediment on sorption, desorption and transformation process in rhizosphere; 3) understand biodegradation behaviors and mechanisms of target compounds by excellent PAH-biodegrading bacteria in mangrove wetlands, and effects of rhizosphere on biodegradation process, as well as the mechanisms; 4) understand the process and mechanisms of adsorption, bioconcentration, decomposition and metabolism of target compounds by mangrove plants.

在刚完成国家基金项目基础上，继续以典型母体多环芳烃(P-PAHs)、并新增烷基取代多环芳烃(A-PAHs)为对象，新建原位、在线同时测定P-PAHs、A-PAHs及其代谢产物的同步荧光、激光诱导纳秒时间分辨荧光法；搭建国内外首个用于环境科学研究的显微荧光光谱系统，并将其用于所述目标物的在沉积物微区结构层面的吸附解吸过程及相关机理研究；用二维GC/MS联用技术考察红树林湿地水及沉积物中目标物的浓度、分布及其来源；结合实验室模拟生态条件及现场、原位研究，探讨红树林湿地中目标物的环境行为及其典型界面过程、机制。揭示：目标物在红树林湿地水-沉积物-根际界面间交换、转运规律、及相关机制，探究沉积物微观结构、特性对吸附/解吸过程、及根际沉积物界面间迁移过程及其影响因素；红树林湿地优势PAHs降解菌对目标物降解过程、机理及根际效应对降解的影响及其机理；红树植物对目标物的吸收富集及分解代谢途径、机制。

在本基金的支持下，依托课题组多年的工作积累和所在国家重点实验室在该研究领域坚实的研究基础，发挥多学科交叉优势，研究了母环及烷基取代多环芳烃在红树林湿地中的环境行为及界面过程机制。首先，利用激光诱导纳秒时间分辨荧光系统 (LITRF) 建立了母环PAHs (P-PAHs) 及烷基化PAHs (A-PAHs) 在红树根表赋存及向组织内部迁移的原位定量测定方法，并在模拟条件下，利用所搭建的显微荧光光谱分析系统 (MFSA) 实现原位定量可视化的检测红树植物侧根表面微区中PAHs以及纳米粒子对根表面微区中PAHs截留行为的影响；建立了MFSA-导数同步荧光光谱法新方法，所建方法降低了沉积物背景荧光的干扰，并籍此初步探讨了红树林沉积物微区中PAHs的分布情况及影响因素。拓展研究了溶解态P-PAHs与A-PAHs的微生物降解过程以及低分子量有机酸存在下对降解过程的影响，并进一步采用双扫描导数-同步荧光光谱法实现了溶解态PAHs及其两种代谢产物的同时测定，所建方法具备原位研究PAHs生物降解的潜力。另一方面，在模拟条件下，采用多光谱结合分子对接法探究了P-PAHs及羟基化PAHs与过氧化氢酶(CAT)、牛血清白蛋白(BSA)的相互作用机制，并考虑羟丙基-β-环糊精(HPCD)的包络作用对其相互作用的影响。此外，利用三维荧光光谱法结合平行因子法(EEM-PARAFAC)研究了藻类释放内源性DOM与PAHs相互作用及释放内源性DOM的光化学转化及微生物转化对其与PAHs结合能力的影响； LITRF结合PARAFAC实现了原位探究PAHs与商品化腐殖酸 (HA)的相互作用，并在此基础上考虑 HA存在下对P-PAHs和A-PAHs生物利用度的影响。为进一步确定A-PAHs的环境行为，调查了九龙江河口水和沉积物中A-PAHs和新型阻燃剂得克隆(DP)的污染水平，探究了DP与A-PAHs对斑马鱼的联合神经毒性作用及机制。利用上述结果，原位可视化研究了P-PAHs和A-PAHs在红树林湿地中的界面过程和环境行为，初步探究了相关机制及影响因素；并更深一步探究P-PAHs及A-PAHs对生物可利用度以及生物毒性的影响，填补了国内所研究区域A-PAHs与其它污染物共存时产生环境效应的空白，为P-PAHs和A-PAHs在红树林生态系统中的污染控制以及机制研究提供了研究基础与思路。