矿物颗粒物形状特征对水体光学特性的影响研究

The inorganic suspended particulate matter plays a significant role in water optical properties. The concentration, component, density, size and shape are interactive and inseparable properties of particles, which are essential to studies in water radiative transfer and biogeochemistry. However, current studies of water optical properties usually take the inorganic suspended particles as homogeneous spheres, but neglect the differences between the random shapes of natural particles and theoretical homogeneous spheres. Aiming at solving this problem, this study chooses three typical Case Ⅱ water, inland lake, estuary, and coastal water, as study areas. On account of filed inspection and laboratory measurement, the basic characteristics of particle shape and best quantitative expression are analyzed. The influences exerted by particles shape on water inherent optical properties are discussed. And on this basis, a new set of correction method for particle size measurement based on shape features of inorganic particles would be established. The research results will provide accurate particle size for relevant researches and further study of water radiative transfer theory.

矿物颗粒物是影响水体光学性质的重要因素，其浓度、成分、密度、粒径、形状等性质相互影响且密不可分，对于水体辐射传输、生物地球化学等研究具有重要意义。现有的水体光学研究大多将颗粒物简化为均质球体，而并未考虑自然条件下不规则矿物颗粒物的形状特征可能引入的误差。为解决上述问题，本研究拟选择我国典型二类水体——内陆湖泊、河口海岸以及近岸海域为研究区，通过野外样品采集和实验室配比测量等方法，分析矿物颗粒物基本形状参数并确定最佳差异性表征因子；研究形状特征量化表征因子对水体固有光学量的光谱映射机制；在此基础上，提出考虑形状特征的矿物颗粒物粒径校正方法，为提高粒径数据测量精度，深入研究水体辐射传输机理打下基础。

原有的水体光学研究大多将矿物颗粒物简化为均质球体，而并未考虑自然条件下不规则矿物颗粒物的形状特征可能引入的误差。本研究通过对比电镜扫描和自制水槽实验的测量结果，分析了颗粒物形状特征对浓度和粒径测量的影响。对于颗粒物质量浓度的估算，随机模式相比球形模式，可以更为准确的估算质量浓度，但随着颗粒物形状逐渐偏离球形，颗粒物浓度高估现象越明显。对于颗粒物粒径分布的估算，相比电镜扫描结果而言，随机模式和球形模式均高估了颗粒物粒径参数，其中随机模式估算的小粒径端更为准确。此外，颗粒物浓度的变化对粒径分布测量也有明显影响，主要表现为随着颗粒物浓度增大，偏离程度逐渐增大，特别是小粒径端。不同形状特征的颗粒物混合对于混合物浓度测量的影响为线性相加的，而对于粒径分布测量的影响较小，仅在小粒径端差异相对较大。因此，在进行颗粒物浓度测量时，若已知该区域的主要成岩矿物及其质量比例，可以采用本研究得到的标准形状颗粒物校正系数，选择相应参数进行线性组合后对测量结果进行校正，从而有效提高测量精度。