考虑热力学并结合同位素技术的近海水交换数值模拟研究

Water exchange ability in coastal sea is intimately linked to the water quality and ecological environment, which is also one of the basic issues in research of coastal marine environment. Numerical simulation method has become the principal tool, however, the water exchange model still needs improvements in accuracy and reliability due to the related confused concepts, the partial consideration, and the absent evidence. Targeted to the Bohai Sea for the survey region, we plan to establish and polish the water exchange model under comprehensive effect of meteorology and hydrology, after considering the phase change of sea water and exploiting the isotope tracer technique veritably recording the water exchange process. The approach integrated by numerical simulation, field monitoring and theoretical analysis are adopted to evaluate the mechanism of thermodynamic and dynamic factors on the water exchange, develop a new way to optimize and verify numerical model based on the isotope tracer technique, and apply a statistical analysis tool with explore statistical approaches to explaining the uncertainty in computed water exchange period. The research result is a scientific instruction for environmental impact assessment of coastal engineering and marine ocean zoning, and provides theoretical evidence for calculating marine environmental capacity and controlling the total mass of pollutants.

近海水交换能力与水质和生态环境等问题有着密切相关，是海岸环境研究中的基础问题之一。数值模拟方法已是研究水交换过程的主要工具，但由于相关概念杂乱，考虑因素片面，直接证据缺乏等问题，水交换模型在精确性和可靠性方面有待完善。本项目拟以渤海为研究区域，考虑海水的相态变化，结合能精准示踪水交换过程的同位素技术，建立并完善气象水文综合作用下的水交换模型。通过数值模拟、现场监测和理论分析等相结合的手段，定量评估热力学、动力学因素对水交换的影响机制；开发基于同位素示踪技术的数值模型优化和验证方法；运用统计分析方法阐明水交换周期计算结果不确定的原因。研究成果对海岸工程环境影响评价和海洋功能区划有科学指导意义，并为海洋环境容量计算及入海污染物总量控制提供理论依据。

水交换模型是用来近海环境容量的重要工具，但传统的水交换模型没有考虑热力学过程的影响，水交换模拟结果的可靠性缺少实测资料验证。本研究通过考虑海冰生消过程的水动力模型再现了辽东湾冰期前后的水动力环流结构，并利用水动力模型驱动计算水体中D和18O的时空演化过程。基于实测的D数据率定模型参数，如湍流混合系数，风拖曳系数，底摩擦系数等，提升模型的预测精度。通过比对冰水两相介质中18O的实测值和模拟值，核实了水交换计算结果的可靠性，估算了海冰对辽东湾和渤海中央海盆之间的水交换过程的影响。通过辽东湾冰期海冰和海水中污染物实测数据，发现石油类和重金属在冰水介质中不同的分配规律，揭示了冰期前后污染物时空分布的特征及其产生的原因。研究成果不仅可以用于提升水交换模型的适用性，还可以为冰区海洋环境容量的研究提供基础数据。