Implications of solid waste dumps on the microplastic abundance in groundwater in Kollam, India

Water pollution caused by microplastics has garnered increasing attention in recent years due to its potential ecological and human health risks. However, there are very limited studies and a general lack of consensus regarding the presence and negative impacts of microplastics in groundwater. Due to their small size, microplastics can easily be transported at surface as well as subsurface levels, potentially reaching the groundwater table and contaminating the groundwater system This contamination is expected to occur more rapidly in landfill areas and other locations where plastic waste is dumped. In this study, we examined well water samples collected from areas near various dumping sites to assess the abundance and characteristics of microplastics. An average of 12 items/L of microplastics were found in groundwater wells near eight dumping sites in Kollam Corporation. The predominant shape of microplastics in the groundwater samples was fibres, followed by flakes, with black being the predominant colour. The areal extent of solid waste dumping was observed to have an influence on the abundance of microplastics. Additionally, the pH of groundwater near heavy dumping sites was found to be in the acidic range, indicating the intrusion of leachate from dumps into groundwater. The study revealed that the leachate from solid waste dumps is the primary source of microplastics in groundwater. Furthermore, a risk assessment of the microplastic pollution was carried out using an index namely Microplastic Pollution Index and the areas of high risks were identified. The locations having heavy solid waste dumping and those near coastal areas were observed to be at high risk, thereby indicating that both the leachate from dumps and sea water intrusion can cause higher microplastic pollution risk in the groundwater system. The findings of this study are expected to support managers in formulating and implementing effective solid waste management plans to mitigate microplastic pollution in the groundwater system.