Impact of Global Major Reservoirs and Lakes on Plastic Dynamics Using a Process-Based Eco-Hydrology Model

Environmental contamination by plastics has been receiving considerable attention from scientists, policymakers and the public. In this study, the process-based model NICE-BGC was extended to couple with LAKE2K in a stratified water quality model to evaluate the global plastic dynamics in both lotic and lentic waters. The new model could simulate riverine plastic transport in inland waters with and without the presence of global major reservoirs and lakes. The result showed the simulated plastic transport with the presence of reservoirs becomes slightly smaller than that without the presence of reservoirs. In particular, the plastic burial simulated by the model became different with and without the lake model when the density of plastic was higher than that of water. This result showed there are limits to the application of the same partial differential equations as in inorganic carbon for the derivatives either with or without the reservoirs as assumed in a previous study by this author, especially when the plastic density is higher than that of water. The model also simulated plastic sedimentation in the global lakes and reservoirs together, and showed that more plastic deposits in the reservoirs than in the lakes with the exception of the Caspian Sea and most of lentic waters are found to deposit more microplastics than macroplastics as pointed out in a previous study. Finally, the weighted average of plastic budget in the global major rivers with the effect of anthropogenic factors such as construction of artificial dams and global lakes in lentic water was quantified. The simulated result also showed that incorporation of the lake model in NICE-BGC led to improved estimates of plastic dynamics in inland waters, and may aid the development of solutions and measures to reduce plastic input to the ocean.