石油污染水体辐射传输特性研究

Research on the radiation transmission characteristics of water bodies is the basis of ocean color remote sensing applications, and is the theoretical basis of accurately detecting water components and their concentration. It plays a significant role in the construction of water ecological civilization and in environment protection. Nowadays, domestic and international researches on the radiation transmission characteristics of water bodies mainly focus on natural water bodies and coastal water bodies of high turbidity. However, few researches pay attention to the radiation transmission characteristics of petroleum contaminated water bodies. Based on the preliminary work, we started with the radiation transfer simulation model, hydrolight, and further analyzed and parameterized the characteristics of the inherent optical properties of petroleum contaminated water, which varied with wavelength and depth. We then established a scattering function and scattering phase function of particles in the state of petroleum material absorption. Furthermore, we described the influence mechanism and characteristics of petroleum pollution on the water optical parameters, such as radiance, irradiance, attenuation coefficient and remote sensing reflectance, and fully explained the radiation transmission characteristics of the petroleum contaminated water body. Finally, we verify the accuracy of the irradiance and remote sensing reflectance of petroleum contaminated waters obtained from bio-optical remote sensing models and in-situ measurements; solved the forward closure problem involved in the researches of radiation transmission characteristics of petroleum contaminated waters. This laid a theoretical foundation for the solution of radiation transmission equation of the petroleum contaminated water and provided reliable basic data.

水体辐射传输特性研究是水色遥感应用的基础，是准确探究水体组分及浓度的理论依据，在水域生态文明建设及环境保护方面具有重要的作用。国内外针对水体辐射传输特性的研究，主要集中在自然水体和高浑浊近岸水体方面，尚无针对石油污染水体的相关研究报道。在前期工作的基础上，从辐射传输模拟模型Hydrolight入手，深入分析石油污染水体的固有光学量随着波长与深度的变化特征并实现参数化，建立表述石油物质吸附状态下颗粒物的体散射函数和散射相函数模型；阐明石油污染对辐亮度、辐照度、衰减系数、遥感反射比等水体光场参数的影响机理，完整地刻画出石油污染水体的辐射传输特性；以Hydrolight模拟输出值为参照，优化现有的水体石油类含量及固有光学参数的遥感反演模型，验证现场测量和遥感提取的辐亮度等参数的准确性；实现石油污染水体辐射传输特性研究的正演闭合，为水体辐射传输方程的精确求解奠定理论基础和提供可靠的支撑数据。

在前两个基金项目资助下，项目组对石油类污染水体的表观光学特性和固有光学特性展开了一系列的研究，建立了固有光学量随波长λ变化的参数化模型以及水体石油类含量Co的遥感反演模型。本项目是前两个基金项目的延续，在已有的研究成果的基础上，基于辐射传输数值模拟模型Hydrolight，针对石油类污染物进入水体后会改变自然水体原有的辐射传输特性的问题展开研究。.主要研究内容包括：①研究石油物质吸附下颗粒物体散射函数与散射相函数模式；②研究石油污染水体固有光学量随深度变化的参数化模型；③研究石油物质对水体光场参数的影响机理；④研究以Hydrolight输出值为标准的水体石油含量遥感反演优化模型。.针对这些研究内容，项目组于2018-2021年共进行了5次配比试验和现场试验，获取样本数据共计268个。基于Hydrolight进行了光学参数的模拟，得到各种数据输出文件共计1400个。运用Mie散射理论的计算方法，建立了石油物质吸附下颗粒物体散射函数β(θ,λ)与散射相函数P(θ,λ)模式，并从多分散性油滴颗粒群的P(θ,λ)建立入手，深入讨论了P(θ,λ)可累加性问题；完成了后向散射系数bb(λ)与吸收系数a(λ)随海水深度h变化的参数化模型，分析了bb(λ)、a(λ)、比吸收系数、Co等物理量随深度变化的特征；从不同的角度针对水体光场参数（遥感反射率、上行辐亮度、漫衰减系数等）随h、传感器天顶角θ和λ的变化特征进行了分析，确定了石油类物质对它们的影响机理；以Hydrolight输出结果为标准优化了Co遥感反演模型，并利用优化模型建立了基于LSTM网络的Co预测模型。.本项目的研究过程与前两个科学基金项目的成果结合，形成了完整的石油类污染水体水色遥感研究体系，有助于推动水色遥感基础研究和应用研究的进程，本项目研究成果也可为水体石油类污染监测提供技术手段。