养殖水体溶解有机质对铜赋存形态的作用机制研究

The pollution of heavy metals in aquaculture water concerning ecological risks has attracted increasing attention. Identifying aqueous heavy metal speciation is an important issue for the healthy development of aquaculture industry. For the emerging environmental issue, the current research only focused on the total amount of heavy metals, with a lack of appreciation of speciation analysis. The project is intended to analyse the molecular composition of freshwater aquaculture-derived dissolved organic matter (DOM) in different seasons by high resolution mass spectrometry (HRMS) and nuclear magnetic resonance spectroscopy (NMR) based on the characterization of the DOM functional groups by spectroscopy and chemometrics. Afterwards, the molecular interaction mechanism between DOM and copper, which was high risk in China’s aquaculture water, will be studied by means of spectroscopy, mass spectrometry and microcalorimetry. The site binding model of interaction between them in a certain concentration gradient will be established. The thermodynamic behavior of the complexation reaction and the speciation evolution of copper-bearing complexes is to be revealed. Furthermore, with the aid of a series of model compounds with gradient changes in the spatial configuration of active sites, the effect of molecular configuration of DOM on the speciation evolution of free copper will be explored. The proposed project is of great theoretical significance for purifying aquaculture environment, ensuring the food safety of aquatic products and enhancing the research value of heavy metal speciation analysis in the field of environmental pollution control.

涉及生态风险的养殖水体重金属污染问题日益引起关注，识别水体中的重金属形态是水产养殖业健康发展的重要命题。对于该环境新兴问题，目前的研究只关注重金属的存在总量，缺乏对其形态分析的研究。本项目旨在利用光谱学和化学计量学方法，表征不同季节淡水型水产养殖水体中溶解有机质官能团类型的基础上，结合高分辨质谱和核磁共振波谱，解析其分子组成信息；再综合利用光谱、质谱、微量热等多种方法，研究溶解有机质与我国养殖水体中安全风险较为突出的重金属铜的分子作用机制，建立两者在一定浓度梯度范围内相互作用的位点结合模型，揭示络合反应的热动力学行为和含铜配合物的形态变化进程；进而借助活性位点空间构型存在梯度变化的系列模型化合物，探索溶解有机质分子构型影响铜离子形态变化的规律。该项目对净化我国养殖水体环境，保障水产品的食用安全，提升重金属形态分析在环境污染物控制领域的研究价值具有重要的基础理论意义。

水产养殖为全球粮食生产做出了巨大贡献。中国的水产捕捞规模远远领先于世界其他国家。尽管溶解性有机质（DOM)）对鱼类生长和生态循环具有潜在的影响作用，但其在水产养殖业中的谱学表征尚不清楚。本研究采用三维荧光-平行因子分析（EEM-PARAFAC）和傅里叶变换离子回旋共振质谱（FT-ICR-MS）技术，解析了中国东部淡水养殖池塘中DOM的分子特征。光谱法分析出DOM的三种主要成分包括腐殖酸类、色氨酸类和酪氨酸类。质谱法对DOM在分子水平进行表征，从元素组成看，CHO>CHON>CHOS，从化合物类型看，木质素>单宁>蛋白质>脂类。腐殖质化指数（HIX）、生物指数（BIX）和荧光指数（FI）等特征光谱指标都反映出DOM腐殖质化程度较低，蛋白源的贡献较大。设计合成了一组亲脂性和空间位阻有差异的硫代氨基脲衍生物（HMTs）作为小分子DOM的代表，HMTs对含铜蛋白酶酪氨酸酶（TYR）的活性表现出明显的抑制作用，抑制能力与HMTs的亲脂性和分子大小密切相关。羟乙基明显有利于提升抑制能力，可作为抑制剂亲脂性的调节基团。采用荧光、红外、液质等谱学方法结合分子对接技术研究其抑制机理。结果表明，HMTs的抑制作用是通过作用于氨基酸残基而不是通过螯合TYR中心的铜离子实现的。每个HMTs都可以插入疏水口袋，通过范德华力和氢键与TYR残基相互作用，静电作用进一步加强了亲和力。本研究加深了我们对水产养殖水体中DOM在环境化学中发挥生物学作用的认识。