A critical review on the sources and instruments of marine microplastics and prospects on the relevant management in China

Abstract

The world's oceans are suffering a constant and unprecedented accumulation of emerging plastic contaminants known as microplastics with a particle diameter smaller than 5mm. Microplastics exhibit a widespread distribution in various habitats from land to the oceans, and even reach the most remote regions - the deep sea and the polar, receiving attention exponentially in the past few years. Owing to their small size, marine species risk getting ingested and entangled in microplastics, causing suffocation, starvation, physical trauma or damage from chemicals, which poses vast and growing threats to biodiversity and the food web. This review article focuses on the various sources attributed to marine microplastics, the latest international, regional and national countermeasures to combat marine litter, as well as the status quo of microplastics pollution, legislation and regulations in China, and furthermore provides improving proposals/solutions on key research gaps, governance and management for future environmental control and policymaking in China.

Soil Pollution from Micro- and Nanoplastic Debris: A Hidden and Unknown Biohazard

“…However, tillage may also limit MPs and NPs mobility in soil due to the plough pan formation and this can increase concentration of plastics in the soil's top layers. The study of plastics debris in sediments of river and in temporary or permanent flooded soils along the coast may provide insights on plastics debris transportation and fate in the soil [82,83]. The deposition of MPs from water columns onto sediments is slow due to the low MPs density, but the deposition rate increases with the hetero-aggregation of MPs by particulate organic and inorganic material due to the increased density of these hetero-particles compared to the separate particles [82,84].…”

“…Furthermore, plastics act as vectors for heavy metal ions in marine environments [82,[113][114][115], while in terrestrial ecosystem, MPs could also act as vectors to increase metal exposure in earthworms [116]. However, the related risk is unlikely to be significant for essentials metals such as Zn that are regulated by metabolic processes [116].…”

“…As discussed by Fuller and Gautam [167], the current methods to extract MPs fragments using the floatation or density separation step with dense salt solutions (NaI and ZnCl 2 ) do not extract plastics from organic samples. The intrinsic difficulties have been clearly highlighted by Wang et al [82], discussing the poor extractive results obtained by coupling organic matter degradative pretreatment with flotation method. In fact, the current methods to extract MPs fragments using the floatation or density separation step with dense salt solutions (NaI and ZnCl 2 ) do not efficiently extract plastics from organic samples [167], mainly because SOM has densities similar to that of several plastics [4].…”

“…In fact, the current methods to extract MPs fragments using the floatation or density separation step with dense salt solutions (NaI and ZnCl 2 ) do not efficiently extract plastics from organic samples [167], mainly because SOM has densities similar to that of several plastics [4]. In addition, methods based on chemical digestion (acid or alkaline solutions) and H 2 O 2 [82] could also degrade plastics debris, whereas those based on enzymes seems to be more plastics friendly [168].…”

Airborne Microplastics

“…Microplastics are classified as primary, if directly manufactured <5 mm, or secondary, as the outcome of fragmentation of larger plastic pieces, during their manufacture, use, maintenance, or release (Duis and Coors 2016). There are endless sources of primary microplastics, such as microspheres, utilized in some cosmetic and personal care products formulation known as microbeads, pellets, used as feeding stock for the plastic manufacturing industries, and microplastic particles, used on airblasting technology (Wang et al 2018). Indeed, identification of sources is a challenging procedure.…”