Evaluation of vertical distribution characteristics of microplastics under 20 µm in lake and river waters in South Korea.

Following the alarming reports of microplastic pollution in the marine environment, increased attention has been given to microplastics in other environmental media. Despite the attention, there is limited research available on the depth-distribution of microplastics in freshwater. Specifically, in the case of water sources used for drinking or tap, the height of intake facilities varies, and it is highly likely that there is a correlation between the vertical distribution of microplastics and these water intake structures. Further, because the size of microplastics varies widely in the environment, the commonly used sampling devices are not suitable for selectively extracting microplastics without causing cross-contamination. Thus, we developed a suitable device for microplastics of size 5-20 µm and studied microplastic distribution in freshwater at various depths by considering various types of microplastics and aqueous systems. Lake and river, two major water sources, were selected for the study of microplastics distribution in water system. The microplastic distribution characteristics in both water systems showed that polypropylene and polyethylene were the most abundant across all depths because of their production volume. Plastic types with higher density were found only at the lower layers, and polystyrene was found in the upper layers because of the environmental effects on its buoyancy caused pore diameter and surface area. The lake and river had higher microplastic distribution in the lower layer and upper layer, respectively. This was because the flow rate in river was higher than that of lake. The higher flow rate reduced the settling velocity in river. Thus, hydrodynamic stability influences the vertical distribution and concentrations of microplastics in the water systems. These results are expected to be used for understanding the behavioral characteristics of microplastics in water systems and to manage water sources.

Microplastics in water systems: A review of their impacts on the environment and their potential hazards.

Microplastics, the microscopic plastics, are fragments of any type of plastic that are being produced today as plastic waste originating from anthropogenic activities. Such microplastics are discharged into the environment, and they enter back into the human body through different means. The microplastics spread in the environment due to environmental factors and the inherent properties of microplastics, such as density, hydrophobicity, and recalcitrance, and then eventually enter the water environment. In this study, to better understand the behavior of microplastics in the water environment, an extensive literature review was conducted on the occurrence of microplastics in aquatic environments categorized by seawater, wastewater, and freshwater. We summarized the abundance and distribution of microplastics in the water environment and studied the environmental factors affecting them in detail. In addition, focusing on the sampling and pretreatment processes that can limit the analysis results of microplastics, we discussed in depth the sampling methods, density separation, and organic matter digestion methods for each water environment. Finally, the potential hazards posed by the behavior of aging microplastics, such as adsorption of pollutants or ingestion by aquatic organisms, due to exposure to the environment were also investigated.