A catchment‐scale perspective of plastic pollution

Abstract

Plastic pollution is distributed across the globe, but compared with marine environments, there is only rudimentary understanding of the distribution and effects of plastics in other ecosystems. Here, we review the transport and effects of plastics across terrestrial, freshwater and marine environments. We focus on hydrological catchments as well‐defined landscape units that provide an integrating scale at which plastic pollution can be investigated and managed. Diverse processes are responsible for the observed ubiquity of plastic pollution, but sources, fluxes and sinks in river catchments are poorly quantified. Early indications are that rivers are hotspots of plastic pollution, supporting some of the highest recorded concentrations. River systems are also likely pivotal conduits for plastic transport among the terrestrial, floodplain, riparian, benthic and transitional ecosystems with which they connect. Although ecological effects of micro‐ and nanoplastics might arise through a variety of physical and chemical mechanisms, consensus and understanding of their nature, severity and scale are restricted. Furthermore, while individual‐level effects are often graphically represented in public media, knowledge of the extent and severity of the impacts of plastic at population, community and ecosystem levels is limited. Given the potential social, ecological and economic consequences, we call for more comprehensive investigations of plastic pollution in ecosystems to guide effective management action and risk assessment. This is reliant on (a) expanding research to quantify sources, sinks, fluxes and fates of plastics in catchments and transitional waters both independently as a major transport routes to marine ecosystems, (b) improving environmentally relevant dose–response relationships for different organisms and effect pathways, (c) scaling up from studies on individual organisms to populations and ecosystems, where individual effects are shown to cause harm and; (d) improving biomonitoring through developing ecologically relevant metrics based on contemporary plastic research.

Food web transfer of plastics to an apex riverine predator

“…Potential adverse outcomes include exposure to cocontaminants (e.g. persistent pollutants), reduced nutrient uptake and disruption of digestive processes, but a dearth of available data preclude speculation (Windsor, Durance, et al, 2019).…”

Plastic debris in rivers

“…Plant species, such as mangrove forest trees and their associated fauna are reported to be negatively affected by plastic litter, as these ecosystems function as accumulation zones (Ivar do Sul et al, 2014;Martin, Almahasheer, & Duarte, 2019). Plastic pollution also negatively impacts human livelihood, as plastic waste clogs urban drainage infrastructure, increasing flood risk (Njeru, 2006;Windsor, Durance, et al, 2019). Furthermore, plastic litter causes severe economic losses through damage to vessels and fishing gear, negative effects on the tourism industry, and increased shoreline cleaning efforts (McIlgorm, Campbell, & Rule, 2011).…”

A microplastic used as infill material in artificial sport turfs reduces plant growth

“…Plastic waste comes in different sizes, and the ecological consequences are likely to depend on the size of the parts or particles and the chemical make‐up (de Souza Machado et al, ; Windsor et al, ). Large organisms, such as sea turtles and whales, may ingest entire plastic bags, and many organisms, also small ones, may ingest small plastic particles (Derraik, ).…”

“…Consequently, research on plastic pollution in aquatic ecosystems has increased in recent years (Eerkes-Medrano, Thompson, & Aldridge, 2015;Jambeck et al, 2015). Much less attention has been paid to the potential effects of plastic pollution in terrestrial environments (Rillig, 2012;Rochman, 2018;Souza Machado, Lau, et al, 2018;Windsor et al, 2019). This is surprising, because the release of plastic in terrestrial ecosystems is likely to be higher than in the oceans.…”