(Micro)plastics from erosion control engineering in China: Environment pollution and prevention strategies
Haoxin Hao1, 2, Fengling Yan1, 2, Zhonglu Guo3*, Junguang Wang3, Qiuxia Wang4, Cuiting Dai5, Cheng Liu1
1Changjiang Water Resources Protection Institute, Wuhan, PR China
2Key Laboratory of Ecological Regulation of Non-point Source Pollution in Lake and Reservoir Water Sources, Changjiang Water Resources Commission, Wuhan, P.R. China
3College of Resources and Environment, Huazhong Agricultural University, Wuhan, PR China
4Yangtze Soil Conservation Monitoring Center, Changjiang Water Resources Commission, Wuhan, PR China
5Hunan Academy of Agricultural Sciences, Changsha, PR China
Corresponding author: Zhonglu Guo
Email: zlguohzau@163.com
Running title: Prevention (micro)plastic pollution in erosion control engineering in China
Abstract
(Micro)plastics are ubiquitous in our daily lives and are becoming a global emerging pollutant with significant threat to ecosystem sustainability. Within the field of soil erosion control engineering (ECE) in China, a wide range of plastic products, such as plastic mesh, planting bags, and plastic geocells, are extensively employed to stable the topsoil and facilitate the restoration of disturbed land. In this paper, we demonstrate the wide distribution of (micro)plastics in ECE across varied landscapes in China, highlighting their relatively high degradation rate induced by ultraviolet irradiation and mechanical disturbance. Furthermore, (micro)plastics in ECE exhibit a propensity for transport through soil erosion processes, thereby heightening the pollution risk to aquatic ecosystems. While the presence of (micro)plastics in ECE raises significant environmental concerns, there could be straightforward and easily implementable preventive strategies. These strategies include meticulous managing plastic usage during the design and completion phases of ECE, replacing plastic materials with biodegradable alternatives, and cleaning and retrieving temporary work materials.
KEY WORDS: Microplastic Pollution; Soil Erosion; Erosion Control Engineering; Ecological Restoration; Prevention Strategies

Introduction

Plastics are increasingly recognized as a significant threat to the sustainability of our ecosystem (Thompson et al., 2009; Rillig & Lehmann 2012). The extensive use and poor management of plastics have resulted in their ubiquitous presence in our daily lives, making them a globally emerging pollutant. Research efforts have predominantly focused on the issue of small plastic debris, particularly microplastics (defined as plastic particles < 5mm), which pose substantial risks to the global biosphere and human health (Thompson et al., 2009; Horton et al., 2017). Previous studies have overwhelmingly examined the sources of microplastics originating from various plastic objects, such as car tires, clothing, paint coatings, and agricultural mulching, through weathering and breakdown processes (Xu et al., 2020; Chen et al., 2022). However, the potential contribution of (micro)plastics from civil engineering has yet to be considered, even though the increasing use of plastic products as alternatives to traditional materials like wood and steel.
In China, erosion control engineering (ECE) is a prioritized practice for preventing soil erosion and restoring disturbed land during construction activities, as mandated by the Soil and Water Conservation Law . With this context, various of plastic products are extensively employed in ECE to stable topsoil and facilitate the restoration of disturbed land, particularly in slopes and riverbanks. Consequently, the excessive use of plastic materials in ECE has the potential to release microplastics into the environment. Therefore, comprehending the sources of (micro)plastics in ECE and their associated environmental risks is crucial for informing measures to prevent and control microplastic pollution. In this paper, we outline the characteristics of (micro)plastic pollution originating from ECE in China and suggest relevant prevention strategies through source control measures, which are relatively straightforward and easily implemented.

Characteristics of (micro)plastic pollution in ECE

2.1 Ubiquitous in construction and ecological restoration projects of China

Plastics are ubiquitous in ECE across China due to its affordability, durability and versatility. Generally, plastic products are used to prevent soil erosion by providing a physical barrier that protect soils from raindrop impact and runoff scouring in temporary work, and are used to stable slopes as well as promote vegetation growth by providing a suitable environment for seed germination and root development during permanent work. Since 1980s, large-scale of plastic mulching (e.g., plastic mesh) as well as plastic reinforcement agent (e.g., plastic geocell) are extensively employed to immediately control soil erosion and reinforcement topsoil during intense construction activity, e.g., road, rail, dam, mines (Figure.1 a-g). In recent years, some so called ecological techniques, which indeed involved incorporating plastics to soils (e.g., planting bag, non-woven geotextile and blanket), are now highly encouraged in various ecological restoration projects to stable channel, promote vegetation growth as well as to rehabilitation of rocky slopes (Figure.1 e-i). Although plastic products have demonstrated effectiveness in mitigating erosion and have a positive impact on vegetation recovery and dust prevention, their large-scale and widespread usage in soil could pose a potential risk of microplastic pollution.