Introduction Nowadays, coastal pollution monitoring consists in study environmental media, such as sediments, water or/and biological samples, as mussels. A new challenge started in 2009 with the International Pellet Watch (IPW), proposing the use of resin pellet as no-living passive samplers, in order to avoid long and high-cost preparation samples of coastal environmental media. Positive correlation (Fig. 1) between POPs concentration in mussels and in resin pellet has been proved during IPW [1]. Fig. 1. Correlation between of ?PCBs in mussels (ng/g-lipid) and in plastic pellets (ng/g-pellet) [1]. Resin pellets are the small virgin plastic particles of different polymeric types from which all plastic objects are made. During plastic production processes, industries and factories disperse resin pellets in the environment and most of them arrive in the ocean standing there for a lot of time. Due to their specific weight almost the same of salt water, many of types of pellets floats in the marine microlayer, and many of them and many of them end up on the beaches. As the main POPs (persistent organic pollutants) and linear hydrocarbons absorption takes place in the microlayer where pollutants are most concentrated than in the water column. In this way pellets can sorb hydrophobic substance [2], [3]. The environmental pollution mapping methods proposed within the IPW is based on Endo et al. (2005) observation regarding a correlation between the degradation state of resin pellets (especially the PE ones) and their POPs content. They sustain that a more pronounced coloring (yellowing) of the pellet should indicate a longer residence time in the sea of such particles, and therefore a greater degradation of their polymeric matrix; the longer time spent in the sea also means a greater probability of having absorbed pollutants dissolved there, from which should follow a correlation between more intense coloration and POPs penetrated. This means that, by selecting the darkest pellets present at different sites, it is possible to get an idea of the degree of pollution in that particular area [4], [5]. As Endo et al. (2005) considerations are supported by a very small number of sampled pellets, we decided to undertake an "Italian pellets survey" in order to investigate, with a greater sample number and so a major statistical accuracy, the structural characteristics of beached pellets, trying to understand if exists a correlation between physical/chemical degradation state, their color (yellowing) and the organic pollutant concentrations. Fig 2. On the left: Discoloration of different polymeric matrix of pellets over time [3]. On the right: Digital photos of the raw pellets of standard of bio-plastic (in black), 6 months-aged in seawater (in blue) and 6-months-aged in sandbox reproducing beach conditions (in orange) [5]. Materials and methods We sampled pellets distributed in all the Italian peninsula during spring/summer of 2019, thanks to the contribution of volunteers of Italian NGO Legambiente. At the moment we have analysed pellets collected from Le Grazie Beach, which is located inside La Spezia Gulf, as shown in Fig.3.
Correlation between POPs absorbed by beached resin pellet and their degradation conditions in several Italian sites: a comparison between "Mussle Watch" and "Pellets Watch" monitoring
S Bronco;L Ricci;C De Monte;S Merlino
2022
Abstract
Introduction Nowadays, coastal pollution monitoring consists in study environmental media, such as sediments, water or/and biological samples, as mussels. A new challenge started in 2009 with the International Pellet Watch (IPW), proposing the use of resin pellet as no-living passive samplers, in order to avoid long and high-cost preparation samples of coastal environmental media. Positive correlation (Fig. 1) between POPs concentration in mussels and in resin pellet has been proved during IPW [1]. Fig. 1. Correlation between of ?PCBs in mussels (ng/g-lipid) and in plastic pellets (ng/g-pellet) [1]. Resin pellets are the small virgin plastic particles of different polymeric types from which all plastic objects are made. During plastic production processes, industries and factories disperse resin pellets in the environment and most of them arrive in the ocean standing there for a lot of time. Due to their specific weight almost the same of salt water, many of types of pellets floats in the marine microlayer, and many of them and many of them end up on the beaches. As the main POPs (persistent organic pollutants) and linear hydrocarbons absorption takes place in the microlayer where pollutants are most concentrated than in the water column. In this way pellets can sorb hydrophobic substance [2], [3]. The environmental pollution mapping methods proposed within the IPW is based on Endo et al. (2005) observation regarding a correlation between the degradation state of resin pellets (especially the PE ones) and their POPs content. They sustain that a more pronounced coloring (yellowing) of the pellet should indicate a longer residence time in the sea of such particles, and therefore a greater degradation of their polymeric matrix; the longer time spent in the sea also means a greater probability of having absorbed pollutants dissolved there, from which should follow a correlation between more intense coloration and POPs penetrated. This means that, by selecting the darkest pellets present at different sites, it is possible to get an idea of the degree of pollution in that particular area [4], [5]. As Endo et al. (2005) considerations are supported by a very small number of sampled pellets, we decided to undertake an "Italian pellets survey" in order to investigate, with a greater sample number and so a major statistical accuracy, the structural characteristics of beached pellets, trying to understand if exists a correlation between physical/chemical degradation state, their color (yellowing) and the organic pollutant concentrations. Fig 2. On the left: Discoloration of different polymeric matrix of pellets over time [3]. On the right: Digital photos of the raw pellets of standard of bio-plastic (in black), 6 months-aged in seawater (in blue) and 6-months-aged in sandbox reproducing beach conditions (in orange) [5]. Materials and methods We sampled pellets distributed in all the Italian peninsula during spring/summer of 2019, thanks to the contribution of volunteers of Italian NGO Legambiente. At the moment we have analysed pellets collected from Le Grazie Beach, which is located inside La Spezia Gulf, as shown in Fig.3.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
