Feng Qi, Chen Zhi, An Chunjiang, Yang Xiaohan, Wang Zheng
Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada.
Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada.
Water Res. 2023 Jun 1;236:119970. doi: 10.1016/j.watres.2023.119970. Epub 2023 Apr 11.
In the present study, the infiltration and resuspension of microplastics (MPs) in a slope substrate under the influence of repeated tidal forces were investigated using a tidal tank. In the scenario in which MPs were placed on the top of the slope, increasing numbers of particles were observed on the water surface with the increase in tidal cycles. More particles of smaller equivalent particle diameter (d) and low density floated to the water surface. The horizontal positions (positive toward the lower tide zone) of MPs showed significant positive correlation with the shortest length c of MPs, MP density, MP weight, d, and Corey shape factor, whereas they showed significant negative correlation with the rate of tidal level change and the longest length a of MPs. The vertical positions (positive in the downward direction) of MPs showed significant positive correlation with the shortest length c of MPs, MP density, MP weight, d, and Corey shape factor, while they demonstrated significant negative correlation with the largest cross-section area and surface tension of MPs. In the scenario in which MPs were placed at the bottom of the tank, the smaller and low-density particles had a higher possibility of moving upward to the water surface under repeated tidal forces. High-density particles also migrated to the water surface due to the surface tension force. Further, a lower rate of tidal level change contributed to more floating of particles. The horizontal positions of MPs showed significant positive correlation with MP density, while they demonstrated significant negative correlation with the largest cross-section area and surface tension of MPs. The vertical positions of MPs showed significant positive correlation with the longest length a of MPs, MP density, MP weight, and d. These results imply that large, high-density, and less flatty particles tend to be distributed in the lower tidal zone and deeper substrate layers. These findings can help understand the redistribution of MPs and assess their risk in the shoreline environment.
在本研究中，使用潮汐试验槽研究了在反复潮汐力影响下微塑料（MPs）在斜坡基质中的渗透和再悬浮情况。在将微塑料置于斜坡顶部的情况下，随着潮汐周期的增加，水面上观察到的颗粒数量增多。更多等效粒径（d）较小且密度低的颗粒漂浮到水面。微塑料的水平位置（朝低潮区为正）与微塑料的最短长度c、微塑料密度、微塑料重量、d和科里形状因子呈显著正相关，而与潮位变化率和微塑料的最长长度a呈显著负相关。微塑料的垂直位置（向下为正）与微塑料的最短长度c、微塑料密度、微塑料重量、d和科里形状因子呈显著正相关，而与微塑料的最大横截面积和表面张力呈显著负相关。在将微塑料置于试验槽底部的情况下，较小且低密度的颗粒在反复潮汐力作用下向上移动到水面的可能性更高。高密度颗粒也因表面张力而迁移到水面。此外，较低的潮位变化率导致更多颗粒漂浮。微塑料的水平位置与微塑料密度呈显著正相关，而与微塑料的最大横截面积和表面张力呈显著负相关。微塑料的垂直位置与微塑料的最长长度a、微塑料密度、微塑料重量和d呈显著正相关。这些结果表明，大的、高密度的和不太扁平的颗粒倾向于分布在低潮区和更深的基质层中。这些发现有助于了解微塑料的重新分布并评估它们在海岸线环境中的风险。
