Читать книгу Plastic and Microplastic in the Environment - Группа авторов - Страница 35

The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) (2015) defines plastic as a synthetic, water‐insoluble polymer, generally of petrochemical origin, that can be molded on heating and designed into various shapes to be maintained during use (Arthur et al. 2009; Lassen et al. 2015).

The plastic pollutants encompass a wide range of synthetic polymers, some of which are polyethylene terephthalate, high‐density polyethene, polyvinyl chloride, polyethene, polypropylene, and polystyrene. These present a wide range of different sizes of plastic polymer materials that are present (meter to micrometers) in our surroundings. According to National Oceanic and Atmospheric Administration (NOAA) and the European Chemicals Agency, MPs are small plastic pieces less than five millimeters.

After entering the ecosystems, these plastic particles undergo degradation and fragmentation processes and it becomes difficult to identify and remove them, particularly the smaller size fractions. These particles are water‐insoluble and not easily biodegradable, and are chemically durable over long periods. These MP pollutants easily move long distances through aeolian transport (Gasperi et al. 2018) and water, and accumulate in the environment. Thus, due to the validation of the long‐range transport of plastics via air and water, the misconception of plastics being a local junk or waste as thought of a few decades ago is now being rebuffed, and plastics are now acknowledged as a serious threat to the global environment.

The threat of plastic pollution can be managed early through efficient source identification. In recent years many researchers have reported potential MP sources, fluxes, and sinks of these pollutants using theoretical models (Figure 2.1) across a wide variety of hydrological reservoirs (Alimi et al. 2018; Browne 2015; de Souza Machado et al. 2018; Horton et al. 2017; Horton & Dixon 2018; Nizzetto et al. 2016; Wagner et al. 2014). Extensive risk management and assessment of this emerging contaminant requires a proper and exhaustive understanding and quantification of the sources and emissions pathways across the world, spatially as well as temporally, with a special focus on freshwater sources and fluxes, This will help in the understanding of the sources, fluxes, and sinks, and contribute immensely to a proper estimation of the global budget of plastics input to the oceans, which can be useful for source mitigation schemes and for planning long‐standing monitoring and assessment strategies.

Figure 2.1 Showing the pathways of plastic fluxes across the various hydrological reservoirs, indicated by brown arrows, which represent the fluxes where extensive research is going on. Blue arrows represent plastic fluxes (theoretical) that have yet to be studied in detail

Source: Modified from Windsor et al. 2019.