Waste Management Outlook for Mountain Regions

Plastic Pollution and Downstream Impacts

One of the far-reaching implications of waste in mountains, particularly waste that is unmanaged or poorly managed, is that it might not always stay in the mountains. Solid waste can end up in rivers, lakes or wetlands after it enters sewage systems, is washed down by rainwater, or blown away by wind. Lakes, including artificial lakes and reservoirs, can act as temporary storage facilities for all kinds of litter, but it is rivers that are the key pathways to lowlands and coastal areas – for water, sediments, pollutants and litter. Once rivers have discharged their content into the ocean, it becomes ‘marine litter’. Waste that was once disposed of on a mountain can find itself on the floor of submarine canyons (Tubau et al., 2015).

In recent years, there has been an increase in interest in marine plastics.However,fewstudieshavefocusedonplasticaccumulation in freshwater systems and rivers, despite their important role in transporting plastics to the sea (Williams and Simmons, 1997; Galgani et al., 2000; Acha et al., 2003; Rech et al., 2014). Plastics production reached 300 million tons in 2014 (Plastics Europe, 2015). Plastic has many applications and advantages and is used in almost all economic sectors because of its specific characteristics – its low cost, durability, strength and lightness. Unfortunately, it is precisely these characteristics that make plastics so persistent and widespread in the environment, causing huge challenges in terms of impact and management (UNEP and GRID-Arendal, 2016). Plastic litter is generally subdivided into larger macroplastics and smaller microplastics, which measure less than 5mm (GESAMP, 2015). Microplastics are either purposefully manufactured (for example, microbeads in abrasives or in cosmetics) or are the result of erosion and fragmentation of larger plastic items. The degradation of plastics depends on physical, chemical and biological conditions but is enhanced by exposure to ultraviolet light and air. Fragmentation into smaller particles increases the dispersal of plastics into the environment. Environmental concerns over plastic are not only related to the volume or aesthetics of waste, but mainly to the impact they might have on humans and other living organisms. Both terrestrial and marine organisms can experience mechanical problems, resulting from ingestion and entanglement. Even when plastic disintegrates into smaller pieces, the polymer within may not completely break down into its natural chemical elements. Most plastics also contain additives to improve their properties such as flame retardants and plasticizers (for example, phthalates), which can easily leach out to contaminate the

surrounding environment. Some of these substances are known to be toxic and cause endocrine disruptions and other potential risks to living organisms (Oehlmann et al. 2009; Teuten et al., 2009) including humans (Talsness et al., 2009). Plastic pollution can also clog drainage systems, which are very important for channelling excess water and preventing flooding, especially after heavy rainfall. When water pipes are blocked by plastic debris, the diverted water can cause local flooding, which, in turn, has the potential to transport more plastics. Plastic pollution is directly linked to human activity, population density and the quality of waste management (Jambeck et al., 2015). Without proper waste management, even low-density populations can heavily pollute freshwater systems with plastics. While there are major uncertainties about the actual quantities of plastic debris in lakes and rivers, high concentrations of microplastics have been found even in remote water bodies. Examples include Lake Hovsgol, a remote lake in a mountainous, sparsely-populated region of Mongolia (Free et al., 2014); in fish from Lake Victoria (Biginagwa et al., 2016); in sediments of remote lakes in the Tibetan Plateau (Zhang et al., 2016); in lake sediments in Italy (Fischer et al., 2016); in the Laurentian Great Lakes (Driedger et al., 2015); in the Yangtze (Zhao et al., 2014); and in the Danube (Lechner et al., 2014). The lack of available data does not allow for a comprehensive assessment of the long-term impacts of plastics on mountain ecosystems and human health. Further research is needed, but prevention, mitigation and adaptation strategies and policies should be urgently designed to address identified sources and pathways to prevent further plastic contamination – including the dispersal of persistent organic pollutants in freshwater systems on which human populations depend for drinking water and food resources.

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