Under the influence of high-intensity human activities, the discharge of chemical pollutants in coastal waters increases progressively year by year and exceeds the marine self-purification capacity, which in turn leads to major marine ecological environmental problems such as eutrophication and excessive heavy metals in water bodies. Hence, studies on the marine environmental capacity (MEC) are the basic work for the total discharge control and water quality improvement of land-based pollutants. In the article, a three-dimensional (3D) water quality model was established based on the unstructured-grid, finite-volume, free-surface and primitive equation coastal ocean model (FVCOM). Then, the mathematical model was calibrated with the data monitored in 2013 and 2014, and the MEC of dissolved inorganic nitrogen (DIN), chemical oxygen demand (COD) and petroleum hydrocarbons (PHs) in the main rivers entering the sea was calculated using the self-purification process integration method. The results indicate that the annual MEC of DIN, COD and PHs pollutants are 3.6 $\times$ 10⁴ t/a, 45 $\times$ 10⁴ t/a and 0.15 $\times$ 10⁴ t/a respectively. By comparing and analyzing the current pollution load, the reduction rates of ammonia nitrogen (NH₄-N) and total nitrogen (TN) in the study area are equivalent to more than 70% of the current load into the sea while COD does not need to be reduced. Only a few river units still have surplus allocated capacity (AC) while the remaining ones need to be cut down. Consequently, the control of total pollutants emission is an urgent issue to be solved. The evaluation on MEC of coastal waters can not only provide technical support for the offshore aquaculture industries, but also provide scientific basis for the total control of terrigenous pollutants in coastal cities in Northern Jiangsu Province.

在高强度人类活动的影响下，近岸海域化学污染物排放量逐年递增，超过海洋自净能力，进而导致海洋富营养化、重金属超标等重大海洋生态环境问题。水体。因此，海洋环境容量（MEC）研究是陆源污染物排放总量控制和水质改善的基础工作。在文章中，基于非结构化网格、有限体积、自由表面和原始方程沿海海洋模型（FVCOM）建立了三维（3D）水质模型。然后，用2013年和2014年监测的数据和溶解无机氮（DIN）的MEC对数学模型进行校准，主要入海河流的化学需氧量（COD）和石油烃（PHs）采用自净化过程积分法计算。结果表明，DIN、COD和PHs污染物的年MEC为3.6$\times$10 ⁴吨/年, 45$\times$10 ⁴吨/年和 0.15$\times$分别为10 ⁴ t/a。通过对比分析当前污染负荷，研究区氨氮（NH ₄ -N）和总氮（TN）的减少率相当于当前入海负荷的70%以上，而无需COD要减少。只有少数河流单元仍有剩余的分配容量（AC），而其余的需要削减。因此，控制污染物排放总量是一个亟待解决的问题。近岸海域MEC评价不仅可为近海养殖业提供技术支持，也可为苏北沿海城市陆源污染物总量控制提供科学依据。