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

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.

Biochar amendment gradually immobilized soil As and Sb over 2 years

“…The temporal changes in metal(loid) immobilization performances add complexity when assessing the long‐term effectiveness of immobilization (Hou et al., 2021; Wang, Hu, et al., 2023; Zhao et al., 2020). On the one hand, we observed that the amended soil underwent a decline in pH over time, which promoted the immobilization of As and Sb but was not favourable for the long‐term immobilization of Cd.…”

Role of biochar toward carbon neutrality

“…Both positive and negative priming could occur for biochar amended soils. The former one refers to the process where carbon mineralization is stimulated, while the latter one refers to the process where the mineralization rate is lowered (thus leading to suppressed CO 2 emissions) (Maestrini et al 2015;Wang et al 2022c). Positive priming is induced via the addition of fresh labile carbon which can stimulate the activities of soil microorganisms, thus accelerating the carbon mineralization process (Fang et al 2019;Keith et al 2011;Zimmerman and Ouyang 2019).…”

Nanoplastic–plant interaction and implications for soil health

“…Weathering of plastics is a major process responsible for the breakdown of larger plastics into micro‐ and nanoplastics (Duan et al, 2021). As‐formed MPs break into even smaller particles with progressive weathering, generating nanoplastics (NPs) whose size fall within the nanometre range (Lau et al, 2020; Wang, Hu, et al, 2022). There is some controversy about the definition of nanoplastics (NPs) (Wang, Wu, et al, 2021).…”