Microplastic accumulation in groundwater: Data-scaled insights and future research

Area of Science:

• Environmental Science
• Hydrogeology
• Ecotoxicology

Background:

• Growing concern over microplastic (MP) risks to human health and ecosystems.
• Increased scientific publications highlight the prevalence of MPs in groundwater.

Purpose of the Study:

• To develop a Contrasting Analysis of Scales (CAS) approach for understanding MP accumulation in groundwater.
• To synthesize existing data for a hierarchical understanding of MP contamination.

Main Methods:

• Compilation and analysis of 386 groundwater samples.
• Application of the CAS approach to differentiate MP accumulation at regional and local scales.
• Investigation of MP entry pathways and transport mechanisms.

Main Results:

• Open groundwater (OG) showed higher median MP abundance (4.4 items/L) than closed groundwater (CG) (2.5 items/L), with greater diversity in OG.
• Regional analysis revealed high MP pollution risk in nature reserves (17.5 items/L) and landfills (13.4 items/L).
• Local-scale transport is influenced by flow paths, with more MPs downstream and long-distance transport of regular-shaped MPs.

Conclusions:

• Anthropogenic activities are key drivers of MP characteristics and distribution in groundwater.
• Groundwater in residential areas with toxic polymers requires focused attention.
• Future research should prioritize network-based monitoring in groundwater-rich areas impacted by landfills, residences, and agriculture.