Microplastics and Water Reserves in Sri Lanka: A Spatial Hotspot and Risk Assessment Framework

Abstract

Microplastic plastic particles smaller than 5 millimeters are increasingly detected in freshwater systems, with potential effects on ecosystems, water treatment operations, and human health. In Sri Lanka, water reserves such as major reservoirs like Victoria, Randenigala, and Kotmale, as well as natural lakes such as Koggala and Bolgoda, and river-fed tanks in the dry zone, are especially vulnerable. This is largely due to rapid urbanization, tourism, aquaculture, and poor solid-waste management practices. This paper presents a nine-part framework to assess the occurrence, sources, transport, and risks of microplastics across Sri Lanka’s inland waters. The proposed workflow brings together field sampling, laboratory characterization using methods such as density separation and FTIR or Raman confirmation, and geospatial hotspot modeling through techniques like Getis– Ord Gi* and kernel density estimation. These are further integrated with hydrological drivers and human pressures. The framework concludes with a tiered risk index designed to help prioritize interventions for drinking-water intakes, irrigation tanks, and recreational lakes.