Article Review
Microplastic
Zeynep Akdogan, Basak Govena and Anthony L Andrady
Environmental Pollution
Abstract
Microplastics (plastic particles <5 mm) are a contaminant of increasing
ecotoxicological concern in aquatic environments, as well as for human health.
Although microplastic pollution is widespread across the land, water, and air, these
environments are commonly considered independently; however, in reality are
closely linked. This study aims to review the scientific literature related microplastic
research in different environmental compartments and to identify the research
gaps for the assessment of future research priorities. Over 200 papers involving
microplastic pollution, published between 2006 and 2018, are identified in the Web
of Science database. The original research articles in ‘Environmental Sciences’,
‘Marine/Freshwater Biology’, ‘Toxicology’, ‘Multidisciplinary Sciences’,
‘Environmental Studies’, ‘Oceanography’, ‘Limnology’ and ‘Ecology’ categories of
Web of Science are selected to investigate microplastic research in seas, estuaries,
rivers, lakes, soil and atmosphere. The papers identified for seas, estuaries, rivers
and lakes are further classified according to (i) occurrence and characterization (ii)
uptake by and effects in organisms, and (iii) fate and transport issues. The results
reveal that whilst marine microplastics have received substantial scientific
research, the extent of microplastic pollution in continental environments, such as
rivers, lakes, soil and air, and environmental interactions, remains poorly
understood.
Introduction
Microplastics [MPs], now a ubiquitous pollutant in the oceans, pose a serious
potential threat to marine ecology and has justifiably encouraged focused
biological and ecological research attention. But, their generation, fate,
fragmentation and their propensity to sorb/release persistent organic pollutants
(POPs) are determined by the characteristics of the polymers that constitutes
them. Yet, physico-chemical characteristics of the polymers making up the MPs
have not received detailed attention in published work. This review assesses the
relevance of selected characteristics of plastics that composes the microplastics,
to their role as a pollutant with potentially serious ecological impacts.
Fragmentation leading to secondary microplastics is also discussed underlining
the likelihood of a surface-ablation mechanism that can lead to preferential
formation of smaller sized MPs.
This review discusses the mechanisms of generation and potential impacts of
microplastics in the ocean environment. Weathering degradation of plastics on
the beaches results in their surface embrittlement and microcracking, yielding
microparticles that are carried into water by wind or wave action. Unlike
inorganic fines present in sea water, microplastics concentrate persistent organic
pollutants (POPs) by partition. The relevant distribution coefficients for common
POPs are several orders of magnitude in favour of the plastic medium.
Consequently, the microparticles laden with high levels of POPs can be ingested
by marine biota. Bioavailability and the efficiency of transfer of the ingested POPs
across trophic levels are not known and the potential damage posed by these to
the marine ecosystem has yet to be quantified and modelled. Given the
increasing levels of plastic pollution of the oceans it is important to better
understand the impact of microplastics in the ocean food web.
Society has become increasingly reliant on plastics since commercial production
began in about 1950. Their versatility, stability, light weight, and low production
costs have fueled global demand. Most plastics are initially used and discarded on
land. Nonetheless, the amount of microplastics in some oceanic compartments is
predicted to double by 2030. To solve this global problem, we must understand
plastic composition, physical forms, uses, transport, and fragmentation into
microplastics (and nanoplastics). Plastic debris/microplastics arise from land
disposal, wastewater treatment, tire wear, paint failure, textile washing, and at‐
sea losses. Riverine and atmospheric transport, storm water, and disasters
facilitate releases. In surface waters plastics/microplastics weather, biofoul,
aggregate, and sink, are ingested by organisms and redistributed by currents.
Ocean sediments are likely the ultimate destination. Plastics release additives,
concentrate environmental contaminants, and serve as substrates for biofilms,
including exotic and pathogenic species. Microplastic abundance increases as
fragment size decreases, as does the proportion of organisms capable of ingesting
them. Particles <20 μm may penetrate cell membranes, exacerbating risks.
Exposure can compromise feeding, metabolic processes, reproduction, and
behavior. But more investigation is required to draw definitive conclusions.
Human ingestion of contaminated seafood and water is a concern. Microplastics
indoors present yet uncharacterized risks, magnified by the time we spend inside
(>90%) and the abundance of polymeric products therein. Scientific challenges
include improving microplastic sampling and characterization approaches,
understanding long‐term behavior, additive bioavailability, and organismal and
ecosystem health risks. Solutions include improving globally based pollution
prevention, developing degradable polymers and additives, and reducing
consumption/expanding plastic reuse.
References
Robert C Hale, Meredith E Seeley, Mark J La Guardia, Lei Mai, Eddy Y Zeng
Journal of Geophysical Research: Oceans 125 (1), e2018JC014719, 2020
Kieran D Cox, Garth A Covernton, Hailey L Davies, John F Dower, Francis Juanes, Sarah
E Dudas
Environmental science & technology 53 (12), 7068-7074, 2019
Institute of Environmental Sciences, Boğaziçi University, 34342 Istanbul,
Prepared by :
Lester S. Bañares
Allijah Denise Labitag
Christian Jay Gabion