An integrated approach for the classification of Plastic Large Micro Plastics (LMP) in beach sand

Contamination of coastal areas by plastic litter represents an emerging issue of concern because of the increasing use of polymeric disposable items, and there is a lack of information about sources, sinks, and pathways of microplastics into these related compartments. Microplastics embedded in beach sand result from combined contributions of various contamination and degradation processes from terrestrial and marine sources. An integrated approach, involving size, shape and color analysis, as well as chemical characterization, for the classification of plastic particles in the 1-5 mm size range, the so-called Large Micro Plastics (LMP), was developed and is here presented. Such size range was moreover selected as a potential subject of study in order to understand the composition and genesis of smaller microplastics (<1 mm) and nanoplastics (<300 µm). Moreover, LMP can be useful markers about ongoing processes of degradation and fragmentation of larger plastic debris. An optimized high resolution photographic procedure coupled with image analysis was developed in order to determine bidimensional size, shape and true color of collected LMP. An instrumental, automated tridimensional particle size and shape analysis was applied for the physical characterization of extracted LMP. The use of Near Infrared Spectroscopy (NIR) and Raman Spectroscopy coupled with Optical Microscopy (OM-RS) allowed the chemical identification of extracted particles. The main aim of the this work was to develop an integrated approach which could allow to correctly define physical information, such as tridimensional size, shape and color of LMP, which are still underestimated [1]. Such approach meets the need to fill the gap between awareness of the LMP presence in marine litter and the evaluation of their transformation pathways from sources to potential environmental targets. The developed approach allowed a detailed physical and chemical characterization of LMP collected from August 2014 to February 2015 on the Lido Island (Venice, Italy), in a coastal protected area never investigated before.