Biodegradable plastics in the marine environment: a potential source of risk?

Abstract

The marine environment is facing the threat of increasing plastic pollution, especially from disposable plastics. Presently, governments worldwide are promoting policies to restrict or prohibit conventional plastics. As one hopeful alternative to conventional disposable/non-durable plastics, biodegradable plastics have attracted much attention and controversy in terms of their definition, environmental impact, and environmental significance, as they may be widely used. Therefore, it is necessary to clarify the facts about biodegradable plastics, understand the current knowledge gaps, and identify promising fields of relevant research. This review briefly introduces some common biodegradable plastics, their mechanisms of biodegradation, indicators for the biodegradation process, and factors concerning biodegradability and summarizes studies on the biodegradation of biodegradable plastics in the marine environment. The lifespan of biodegradable plastics varies greatly due to their compositions/properties as well as significant differences in the marine environment. Then, the potential risks of biodegradable plastics, including the release of pollutants (micro/nanoplastics, degradation products, and additives), adsorption-desorption of pollutants (pesticide, etc.), and their impact on biomes and biogeochemical cycles are discussed, fully revealing their possible impacts on the marine environment. It is believed that, in addition to the waste of resources, a high abundance of microplastics, toxic leachates, and complex effects on habitats and the environment may also cause problems for the marine environment as a result of the widespread and inappropriate use of biodegradable plastics. Based on the discussion, some constructive suggestions on how to use biodegradable plastics reasonably and prudently in the future are put forward.

Meta-Analysis of Satellite Observations for United Nations Sustainable Development Goals: Exploring the Potential of Machine Learning for Water Quality Monitoring

“…Sedimentation is a form of water pollution caused by the introduction of organic and inorganic matter, including soil particles, into rivers, lakes, and streams as suspended or settleable solids in the water column [106]. Excessive sedimentation can reduce water clarity and increase turbidity, decreasing light penetration and dissolved oxygen levels and harming aquatic organisms [106,107]. In addition to reducing clarity, increasing turbidity, and decreasing dissolved oxygen levels, sedimentation can also contribute to the transport of various pollutants [92,[106][107][108][109].…”

“…Excessive sedimentation can reduce water clarity and increase turbidity, decreasing light penetration and dissolved oxygen levels and harming aquatic organisms [106,107]. In addition to reducing clarity, increasing turbidity, and decreasing dissolved oxygen levels, sedimentation can also contribute to the transport of various pollutants [92,[106][107][108][109]. For example, sediment-laden pollutants such as agrochemicals, including herbicides, pesticides, and fertilizer nutrients, as well as microplastics, can be carried into water bodies by sedimentation [92,[106][107][108][109].…”

“…In addition to reducing clarity, increasing turbidity, and decreasing dissolved oxygen levels, sedimentation can also contribute to the transport of various pollutants [92,[106][107][108][109]. For example, sediment-laden pollutants such as agrochemicals, including herbicides, pesticides, and fertilizer nutrients, as well as microplastics, can be carried into water bodies by sedimentation [92,[106][107][108][109]. These pollutants transported by sedimentation contribute towards eutrophication, toxic chemical pollution, and microplastic pollution in water.…”

“…Sediment transport into water is not only influenced by natural processes, such as rainfall run-off and ice-melt, but also by human activities that increase soil erosion, such as land use changes, construction activities, and deforestation. Climate-change-induced extreme rainfall events, landslides, or glacial melts can exacerbate the issue by increasing sediment-laden pollutants based soil erosion into aquatic ecosystems [106][107][108][109]. These events can cause more soil erosion and transport, leading to higher sedimentation rates in water bodies.…”