辽东湾叶绿素a与营养盐分布特征的数值模拟

Numerical simulation of concentration distribution characteristics of ecological indicators in Liaodong Bay based on Delft3D model

为探究辽东湾海域内叶绿素a与营养盐的时空分布特征及相互作用机理,基于数值模拟(Delft3D)方法构建了叶绿素a (Chl-a)、溶解氧(DO)、氨氮(NH_(4)^(+)-N)、硝酸盐氮(NO_(3)^(-)-N)和活性磷酸盐(PO_(4)^(3-)-P)等生态指标在辽东湾海域的生态动力学模型(Delft3D-ECO),并在验证模型的基础上分析了叶绿素a等生态指标浓度在辽东湾海域的时空变化和分布情况。结果表明:在季节变化上,叶绿素a质量浓度表现为秋季(4.83μg/L)>夏季(4.13μg/L)>春季(3.39μg/L),DO质量浓度表现为春季(9.41 mg/L)>夏季(7.26 mg/L)>秋季(5.84 mg/L),NO_(3)^(-)-N质量浓度表现为春季(0.76 mg/L)>秋季(0.56 mg/L)>夏季(0.50 mg/L),NH_(4)^(+)-N质量浓度表现为春季(0.039 mg/L)>秋季(0.030 mg/L)>夏季(0.026 mg/L),PO_(4)^(3-)-P质量浓度表现为秋季(0.025 mg/L)>夏季(0.020 mg/L)>春季(0.018 mg/L);在空间分布上,辽东湾海域中的叶绿素a、PO_(4)^(3-)-P(春、夏)、NO_(3)^(-)-N(春、夏)质量浓度分布呈东北高、西南低的特点,NH_(4)^(+)-N质量浓度呈研究区域湾顶与湾口高、中部低的特征。研究表明,辽东湾顶部的辽河、大辽河是影响辽东湾海域生态指标浓度时空分布的重要因素,辽东湾海域的营养盐限制作用表现为磷相对限制。

In order to explore the temporal and spatial distribution characteristics and interaction mechanism of chlorophyll a and nutrients in the Liaodong Bay,an ecological dynamic model is established including ecological in-dicators such as chlorophyll a(Chl-a),dissolved oxygen(DO),ammonia nitrogen(NH_(4)^(+)-N),nitrate(NO_(3)^(-)-N),and active phosphate(PO_(4)^(3-)-P)based on the numerical simulation method(Delft3D model),in Liaodong Bay based on Delft3D model.The accuracy of the model was verified,and then the spatial-temporal changes and distri-bution of ecological indicator concentrations including Chl-a in the Liaodong Bay waters were analyzed.The results showed that there were obvious spatial and temporal distribution characteristics of the ecological index concentra-tions in the Liaodong Bay.A trend of autumn(4.83μg/L)>summer(4.13μg/L)>spring(3.39μg/L)in the concentration of Chl-a was observed,spring(9.41 mg/L)>summer(7.26 mg/L)>autumn(5.84 mg/L)in concentration of NO_(3)^(-)-N was found,spring(0.76 mg/L)>autumn(0.56 mg/L)>summer(0.50 mg/L)in con-centration of DO was occurred,spring(0.039 mg/L)>autumn(0.030 mg/L)>summer(0.026 mg/L)in the concentration of NH_(4)^(+)-N,was found and autumn(0.025 mg/L)>summer(0.020 mg/L)>spring(0.018 mg/L)in concentration of PO_(4)^(3-)-P was observed.In terms of spatial distribution,the high concentration distribution of Chl-a,PO_(4)^(3-)-P(spring and summer)and NO_(3)^(-)-N(spring and summer)was found in the northeast Liaodong Bay and low in the southwest Liaodong Bay,and the concentration of NH_(4)^(+)-N was high at the bayhead and baymouth and low in the middle.It was found that the important factors affecting the temporal and spatial distribu-tion of ecological index concentrations were of Liao River and Daliao River at the upper basin of Liaodong Bay,with the relative limitation of phosphorus as nutrient limitation in the Liaodong Bay.