微塑料对结冰过程中环境因子迁移的影响

为探究结冰过程中微塑料赋存对典型环境因子(总氮、总磷、盐度、化学需氧量、悬浮物)等分布及迁移规律的影响,采用室内模拟的方式研究不同条件下(结冰比例、结冰温度及方式、初始浓度)各典型环境因子在冰-水相间的分布及迁移规律,采用物质分配系数(K)表征环境因子的迁移能力。结果表明,结冰过程中冰体对环境因子具有排斥作用,不同条件下微塑料赋存对环境因子的分布规律均有一定程度的影响,由于微塑料自身特性致使原本应迁移至冰下水体中的环境因子部分滞留于冰体中,导致冰体中环境因子浓度的提高,为对照组冰体中环境因子浓度的1.13~1.49倍;同时使冰下水体中环境因子浓度下降,为对照组冰下水体中环境因子浓度的0.73~0.93倍;微塑料的赋存同时导致环境因子分配系数K值提高0.04~0.18,致使环境因子向冰下水体迁移的能力下降,但微塑料的赋存并未改变结冰过程中环境因子由冰体向冰下水体迁移的趋势,微塑料对于环境因子的携带作用小于冰体对环境因子的排斥作用;同时不同条件下结冰过程中微塑料对环境因子分布与迁移机理的影响均可以从结晶学角度与共晶理论得到解释。

Effect of microplastics on the transport of environmental factors during icing and the mechanism of action

In order to explore the influence of microplastics reserve on the distribution and migration of typical environmental factors (total nitrogen, total phosphorus, salinity, chemical oxygen demand and suspended solids) during the icing process, the indoor simulations were adopted to study the distribution and migration of typical environmental factors in the ice-water phase under different conditions (icing ratio, freezing temperature and mode and initial concentration). The migration ability of environmental was characterized by material distribution coefficient(K). The results showed that the ice had a repulsive effect on environmental factors during the freezing process, and the occurrence of microplastics under different conditions had a certain degree of influence on the distribution of environmental factors. The environmental factors that should have migrated to the water under the ice were partially retained in the ice due to the characteristics of microplastics, resulting in an increase in the concentration of environmental factors in the ice, which was 1.13~1.49 times that of the control group. At the same time, the concentration of environmental factors in the subglacial water decreased, which was 0.73~0.93 times that of the control group. The presence of microplastics also increased the partition coefficient K of environmental factors by 0.04~0.18 and decreased the ability of environmental factors to migrate to subglacial waters. However, the occurrence of microplastics did not change the trend of environmental factors transferring from ice to subglacial water during the freezing process. The carrying effect of microplastics on environmental factors was less than the repulsion effect of ice on environmental factors. At the same time, the influence of microplastics on the distribution and migration mechanism of environmental factors during freezing under different conditions could be explained from the perspective of crystallography and cocrystal theory.