天津滨海地下水排放与营养盐输入研究

Over the last two decades,SGD is increasingly being recognized as an important factor in the understanding and sustainable management of coastal fresh aquifers and marine environment. SGD has been recognized to be a potentially significant source of freshwater and of nutrients and other dissolved chemical species to the coastal zone.The proposal choice the Tianjin coastal zone as research site,the research included fieldwork, laboratory experiments,and computer modeling.Quantifying SGD and associated nutrients from land aquifer by using hydrogeological survey and modeling.SGD flux will be estimated based on direct measurements by means of seepage meter, and its relations with driving forces and contributing factors like wave, tide, water depths will be explored. The magnitude of SGD along research site would be calculated by integrated using Ra isotopes.The water residence time will be determined using ratios of the short-lived radiotracer pair Ra-223 and Ra-224.We will use a mass balance model based on Ra-226 activities.to calculate the magnitude of SGD.SGD-driven nutrient fluxes are calculated by multiplying the average nutrient concentrations in groundwater with the SGD fluxes.Results were compared and complement with each other.This project has contributed to marine environmental management and the understanding of land/sea interactions by providing important estimates of SGD and associated nutrients fluxes to the sea.

近二十年来，海底地下水排泄（SGD）被认为是影响海岸带含水层和海洋环境的重要因素，对于滨海淡水和化学组份输入具有重要意义。本研究选择天津滨海带为研究场地，采用野外调查、实验室分析测试和数值模拟的方法开展SGD及其携带的营养盐研究。利用水文地质调查和数值模拟方法，查明陆地潜水向海洋的排放量。利用渗透计现场测量SGD，同时研究海水深度、波浪、潮汐等对SGD的影响。利用不同半衰期镭同位素集成使用的示踪方法，采用半衰期短的Ra-223、Ra-224确定水体滞留时间，利用半衰期长的Ra-226质量平衡方程计算SGD通量，以营养盐浓度与SGD通量关系计算营养盐通量。三种方法，相互补充，相互验证。研究成果提出渤海湾地下水排泄的证据及量值估计，为渤海环境管理提供科学依据。