河网连续动态模型构建及其在典型杀生剂时空迁移模拟中的应用

以三氯生（TCS）和三氯卡班（TCC）为目标污染物，通过监测评价新冠疫情期间杀生剂的河网污染特征；同时，构建了一维水动力学模型和四级逸度模型耦合的河网连续动态模型，解决了污染物在河网迁移过程中的时间和空间异质性问题，开展了目标杀生剂在石马河流域的迁移模拟.模型通过率定和实际浓度验证，获得了满意的模拟结果.结果表明，新冠疫情期间河网中杀生剂的污染浓度是非疫情期间的2倍.TCS和TCC从污水处理厂排出后，在河道中的浓度随着河流迁移的距离增大，呈现先升高后降低的趋势；而浓度的时间变化特征则受到河段流量的影响，上游低流量区域河网中杀生剂浓度先上升而后下降，且在20 h左右已逐渐趋于稳定；下游高流量区污染浓度呈现梯形缓慢升高趋势，且浓度最终在24 h时尚未成为稳定值.因此，对河网中典型杀生剂迁移的时空特征的评估，需在区别流量大小的前提下，分段和分时进行.

Construction of Continuous Dynamic Model for River Networks and Its Application in Simulation of Spatiotemporal Migration of Typical Biocides

Biocides are widely added to personal care products and enter the environment through sewage treatment plant (STP) discharge, which affects ecological health. This paper evaluated the pollution characteristics of triclosan and triclocarban in a river network during the COVID-19 epidemic. Moreover, a continuous dynamic river network model coupling a one-dimensional hydrodynamic model and four-level fugacity model was established to address the temporal and spatial heterogeneity of pollutants in the river network migration process; then, this model was applied to evaluate two biocides in the Shima River Basin. The model passed calibration and in-field concentration verification tests and yielded satisfactory simulation results. The results of the study showed that the concentration of biocides in the river network during the new crown epidemic was twice that of the non-epidemic period. The concentration of triclosan and triclocarban in the river channel first increased and then decreased with the increase of the river migration distance after STP discharge. The time variation characteristics of the concentrations were affected by the river flow. The biocide concentration in the river network of the low flow upstream area first increased and then decreased, gradually stabilizing in about 20 h. The pollution concentration in the high flow downstream area was increased, and the concentration did not stabilize at 24 h. These results indicate the necessity of evaluating the temporal and spatial characteristics of migration of typical biocides in the river network by stages and time on the premise of distinguishing the flow.