Identification of microplastics and associated contaminants using ultra high resolution microscopic and spectroscopic techniques

Abstract

The present study establishes a new procedure to characterize micro(nano)plastics (MNPs) and identify contaminants adhered to the plastic particles in aquatic environments by applying ultra-high resolution microscopy and spectroscopy techniques. Naturally fragmented microplastics (MPs) were collected from Manzanillo and Santiago Bays, Mexico and analyzed using: Confocal Laser Scanning Microscopy (CLSM), Fourier-Transform Infrared Spectroscopy (FTIR), μ-RAMAN, Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Environmental Electron Scanning Microscopy (ESEM). The information obtained from each of these techniques was integrated to produce a comprehensive profile of each particle. Sample preparation was tested by applying three different rinses (unrinsed, distilled water and alcohol) to untreated MPs collected from Manzanillo Bay, finding that when large impurities are present an alcohol rinse makes it easier to examine the associated contaminants. Based on this emerging methodology, polyethylene and polypropylene MPs were identified with associated contaminants such as arsenic, cadmium, aluminum, and benzene. This study demonstrates the presence of pollutants that may be linked to MNPs in aquatic ecosystems and proposes an accurate relatively fast procedure for their analysis that does not require chemical extraction.