Microplastics as a vector for micropollutants in aquatic environments

Project Description

Any plastic particle that measures less than 5 mm in all dimensions is considered to be a microplastic. Microplastics have become a prevalent contaminant in most aquatic environments; conventional water and waste water treatment methods struggle to remove these particles sufficiently and from preventing them from entering the food web. Furthermore, ingestion by aquatic organisms leads to an additional accumulation of microplastics in the food web. Apart from ecological implications on aquatic fauna, microplastics have been shown to act as a vector for certain chemicals such as pyrene. In a pilot study we have demonstrated that two analogues of the cyanobacterial toxin microcystin can adhere to microplastic particles (manuscript in preparation). Microcystins are one of the most prevalent environmental toxins produced by cyanobacteria, a group of microorganisms found predominantly in the aquatic environment worldwide. Under favorable climatic conditions, and given high levels of nutrients in the water, cyanobacteria can present in mass occurrences call blooms. Due to an immense increase in biomass, blooms are ecologically and economically challenging. When blooms are formed by cyanobacterial species capable of producing toxins, a further layer of complication is added as cyanobacterial toxins are potent and can affect aquatic and terrestrial fauna and humans alike. Common exposure routes to cyanobacterial toxins for humans include ingestion through poorly treated drinking water or during recreational activities on or in affected water bodies. However, microplastics acting as a vector could represent a new exposure route via the food web. Other micropollutants, such as pharmaceuticals excreted by humans, may also enter the food web via the microplastic vector route. Another aspect of concern in the described scenario is the potential for the underestimation of micropollutant concentrations in water samples. Many published water sampling protocols require environmental samples to be filtered prior to micropollutant analysis, removing any suspended particles to determine dissolved concentrations. This practice might lead to and underestimation of the micropollutant concentration if the pollutants adhering to the surface of microplastic particles are biologically available.

In collaboration with Marine Scotland