Aging of colloidal contaminants and pathogens in the soil environment: Implications for nanoplastic and COVID-19 risk mitigation

Authors: WANG, LIUWEI - TSINGHUA UNIVERSITY; HU, ZHONGTAO - TSINGHUA UNIVERSITY; YIN, HANBING - TSINGHUA UNIVERSITY; Bradford, Scott; LUO, JIAN - GEORGIA INSTITUTE OF TECHNOLOGY; HOU, DEYI - TSINGHUA UNIVERSITY

Submitted to: Soil Use and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2022
Publication Date: 10/7/2022
Citation: Wang, L., Hu, Z., Yin, H., Bradford, S.A., Luo, J., Hou, D. 2022. Aging of colloidal contaminants and pathogens in the soil environment: Implications for nanoplastic and COVID-19 risk mitigation. Soil Use and Management. 39(1):70-91. https://doi.org/10.1111/sum.12849.
DOI: https://doi.org/10.1111/sum.12849

Interpretive Summary: The migration of colloidal contaminants like disease causing viruses and nanoplastics in soils and groundwater can pose a risk to the quality of drinking and irrigation water resources. The long-term fate of these colloidal contaminants in soils is dependent on aging processes. This manuscript reviews the physical, chemical, and biological factors that influence the aging of viruses and nanoplastics. Results highlight the role of aging on colloid release and destruction/inactivation. Changes in surface properties and variability in colloid release and inactivation are expected in natural environments, and this suggests that existing models to describe these processes are too simplistic. This information will be of interests to scientists, health officials, and government regulators that are concerned with assessing and mitigating risks from colloidal contaminants.

Technical Abstract: Colloidal contaminants and pathogens are widely distributed in soil, whose tiny sizes and distinct surface properties render unique environmental behaviours. Because of aging, colloids can undergo dramatic changes in their physicochemical properties once in the soil environment, thus leading to diverse or even unpredictable environmental behaviour and fate. Herein, we provide a state-of-art review of colloid aging mechanisms and characteristics and implications for risk mitigation. First, we review aging-induced formation of colloidal contaminants and aging-associated changes. We place a special focus on emerging nanoplastic (NP) contaminants and associated physical, chemical, and biological aging processes in soil environments. Second, we assess aging and survival features of colloidal pathogens, especially viruses. Viruses in soils may survive from several days to months, or even several years in groundwater, depending on their rates of inactivation and the reversibility of attachment. Furthermore, we identify implications for risk mitigation based on aging mechanisms. Hotspots of (photo)chemical aging of NPs, including plastic gauzes at construction sites and randomly discarded plastic waste in rural areas, are identified as area requiring greater research attention. For COVID-19, we suggest taking greater care in regions where viruses are persist for long periods, such as cold climate regions. Soil amendment with quicklime (CaO) may act as an effective means for pathogen disinfection. Future risk mitigation of colloidal contaminants and pathogens relies on a better understanding of aging mechanisms and more sophisticated models accurately depicting processes in real soil environments.