Agcumulate: A study on the accumulation of microplastics in soils and terrestrial ecosystems

Microplastics are tiny plastic particles (≤ 5 mm) that are raising much concern due to their potential effects on living organisms, since plastics can leach chemical constituents that can be harmful, some known to possess endocrine disrupting or carcinogenic properties. Microplastics also have the capacity to absorb and act as vectors for organic pollutants and heavy metals in the environment. Microplastics have been found across various ecosystems including terrestrial environments, freshwater environments, marine, air and recently in the human body. Microplastics are well studied in aquatic environments, however; research on microplastic pollution in terrestrial environments including agricultural soils is limited. This research is the first in Ireland to take a holistic approach to addressing microplastic pollution in agricultural soils. A social science study examining the attitudes and behaviours of Irish farmers toward agricultural plastics revealed that while most farmers actively recycle agricultural plastic waste and recognise the importance of agricultural plastics in farming operations, they also expressed significant concerns about the environmental impact of agricultural plastics. Through field studies, this research shows that microplastics are prevalent in agricultural soils across multiple farming land-uses in Ireland with soils applied with biosolids and plastic mulch films containing significantly higher concentrations of microplastics in comparison to soils without these amendments. Pot trial experiments were conducted to investigate the potential effects of microplastics on the growth of two grassland species, and on soil chemical and biological properties. The results were variable, with certain types of microplastics having positive and negative effects or no impact. In the final study, microplastics were abundant in domestic wastewaters from a rural community in Ireland, as were the pond sediments in the wastewater treatment facility. One of the main issues that stems from this is that the sludges produced in these systems are often applied to agricultural land as fertiliser, which introduces microplastics into agricultural soils and the wider environment. This research highlights the pervasive presence of microplastics in terrestrial ecosystems and identifies numerous areas for future related research to build on. Addressing the issue of microplastic pollution in terrestrial environments will require a collaborative approach involving researchers, innovators, industry leaders, agricultural stakeholders, the general public, and policymakers.