By Luke Morales
The convenience of plastic results in its application in various industrial, commercial, and agricultural industries (Ali et al., 2021). From 1950 to 2018, global plastic production was estimated to be at 8.3 billion metric tons, increasing by 185 million tons annually (Ali et al., 2021). Of this plastic produced, 76% (6.3 billion metric tons) ended as waste and can be divided into: “14% recycled, 14% incinerated, and 72% landfilled or released into the environment” (Ali et al., 2021, p. 2). Most types of plastics take up to centuries to completely decompose in the natural environment, so they tend to accumulate (Ali et al., 2021). The accumulation of plastics in the environment is significant because “plastic wastes can act as a carrier for organic pollutants, chemicals, heavy metals, and pathogens” (Ali et al., 2021, p. 3). Estimating the amount of plastic waste in the environment, however, is difficult because of the lack of accurate data available (Hahladakis, 2020). This article will reveal general climatic threats (terrestrial, aquatic, and atmospheric) attributed to plastic pollution and demonstrate the need for further research to allow for the implementation of efficient eco-friendly treatment options within the Latin American region and abroad.
About 4.5 billion tons of plastic waste from 1950 to 2018 ended up in landfills or were released into the environment (Ali et al., 2021). Landfilling in particular “results in soil infertility, since more than 500 years are needed for complete decomposition” (Ali et al., 2021, p. 2). These plastics contaminate the soil by settling on the surface or by entering the soil’s layers, which, aside from landfilling, can occur via fertilizers, wastewater irrigation, sludge, or other sources (Ali et al., 2021). One study examining the effects of microplastics on plant communities using soil from a town in Brandenburg, Germany found that, “in the short term, microfibers [microplastics] increased plant productivity and modified root morphological traits” (Lozano & Rillig, 2020, p. 6171). However, this allowed for the promoted growth of a highly invasive species, called Calamagrostis (Lozano & Rillig, 2020). The invasion of this species has contributed to biodiversity decline, revealing that microplastics may strongly affect community biomass, species abundance, and survival (Lozano & Rillig, 2020). Additionally, the researchers of this study explained that they do not know what long-term effects of microplastics in the soil may have, citing pathogens, as well as toxic substances already present in microplastics as two examples of potential effects (Lozano & Rillig, 2020).
When it comes to sludge specifically, Latin America is a region that lacks in proper sewage sludge management, as it rarely gets adequately disposed; it has become common practice to use sludge as fertilizer (Corradini et al., 2019; Laura et al., 2020). Within the region, there is scarcely wastewater quality data, and though wastewater treatment plants efficiently remove microplastics from sewage, they also concentrate these microplastics into the sludge (Corradini et al., 2019). Corradini et al. (2019) aimed to evaluate the microplastic contamination of soils due to sludge application in Chile. The studied area was located in Mellipilla county, within a 10km2 area near the Maipo river. It included 30 fields that had been treated with sludge over the 10 years prior. Their research revealed that, following each application of sludge to the soil, there was an increase in the amount of microplastics contained in the soil, and that the control site had the lowest concentration of microplastics (Corradini et al., 2019). Additionally, Corradini et al. concluded that further research is needed to understand how pollutants occupy and impact soil (Corradini et al., 2019). With such few studies addressing soil microplastic contamination, the true scale of the problem is left unknown, which may prove detrimental to the different agricultural environments within Latin America, such as those in semi-arid, tropical, and mountainous regions (Corradini et al., 2019).
Based on a United Nations Centre for Regional Development report in 2019, the southeastern countries of Asia were ranked first in plastic wastes mismanagement, with 88% of plastic wastes ending up in water bodies (Ali et al., 2021). “In 2020, 195 countries were estimated to produce about 400 [million tons] of plastic waste, with about 8.8 [million tons] entering the ocean” (Ali et al., 2021, p. 3). The precise timeline for the degradation of plastics in the marine environment is unknown, and fragmentation (breaking apart into smaller pieces) seems more likely than degradation, which may threaten marine biodiversity (Ali et al., 2021; Hahladakis, 2020). For example, a study conducted in 2013 researched the effects of microplastics and additive chemicals to lugworms by exposing the worms to sand, of which 5% consisted of these microplastics and additives (Browne et al., 2013). The short-term (10 days) experiments showed that, through microplastic consumption, the worms ingested large enough concentrations of additives or pollutants to reduce survival, feeding, immunity, and antioxidant capacity (Browne et al., 2013). These researchers concluded by stating that “ingestion of microplastic by organisms can transfer pollutants and additives to their tissues at concentrations sufficient to disrupt ecophysiological functions linked to health and biodiversity” (Browne et al., 2013, p. 2391). Thus, being that the lugworm findings are applicable to marine biota, it is important to consider the negative effects of plastic wastes on these marine species.
When coupled with the many unknowns of plastics in the marine environment, we must consider potential implications of the deposition of such amounts of plastic wastes. Major sources of plastic waste released into the environment include wastewater treatment plants, urban pollution, industry activities, and storms (Li et al., 2021). A study published in 2018 discussed the toxic effects of plastic on the environment (including the aquatic) in Bangladesh. The study found that harmful chemicals from chlorinated plastic can seep into groundwater and other water sources, which causes harm to species that drink said water (Proshad et al., 2018). Additionally, being that florae in general act as a major carbon sink, “some scientists believe that the bobbing pits of polymer in the oceans could contribute to global warming by creating a shaded canopy that makes it harder for plankton to grow” (Proshad et al., 2018, p. 4).
Few studies thus far have focused on the effects of plastic pollution on freshwater systems in particular (Blettler et al., 2017). The Paraná River is one such system, and is among the largest rivers in the world according to its mean annual discharge into the ocean (Blettler et al., 2017). It has an area of over one million square miles and runs through Brazil, Paraguay, Bolivia, and Argentina (Britannica, 2019). It also supports 19 large cities and has significant ecological, cultural, and economic importance (Blettler et al., 2017). In 2017, Blettler et al. examined plastic pollution in Setúbal Lake, which is one of the larger freshwater lakes of the Paraná (Blettler et al., 2017). Following their survey of the shores, two transects, and analyzation of collected plastics, the researchers concluded that “an alarming number of macroplastics were recorded by comparison with other studies worldwide” (Blettler et al., 2017, p. 11). Additionally, the plastics observed posed a risk to the lake ecosystem and suggested a need to improve environmental policies and educational strategies (Blettler et al., 2017). Aside from the threat of plastic accumulation in the environment, we must consider potential threats of plastic creation and destruction as well.
The process of manufacturing plastic releases a large quantity of harmful gases into the air, such as carbon monoxide, dioxins, and hydrogen cyanide, which may pose a serious threat to the atmospheric environment (Ali et al., 2021). Similar effects are observed in the destruction of plastics. Incineration is currently considered as one of the main sources of air pollution, as it also releases pollutants into the atmosphere, such as metals, methane, carbon dioxide, and other substances (Ali et al., 2021). Researchers found that “most incinerators operate without add-on air pollution control devices,” and that, despite not knowing the entire range of effects on human health caused by their exposure, “numerous chemical substances with unknown toxicity are emitted” (Ali et al., 2021, p. 5). Currently, plastics are most frequently present in the air as fibers, which largely originate from consumption of plastic wastes, wind erosion, and urban dust (Li et al., 2021). Without first having a comprehensive awareness of the effects of these substances on the environment and on human health, it is impossible to know the extent of the impacts of plastic manufacturing, destruction, and waste.
Researchers in 2019 estimated the global impact of uncontrolled burning of waste, and they stated that black carbon was a “particularly serious air pollutant emitted from the uncontrolled burning of waste in open fires because it has a global warming potential up to 5000 times greater than carbon dioxide and is also linked to detrimental health impacts” (Reyna-Bensusan, 2019, p. 629). Two billion people lack access to local waste collection services and resort to disposal of household waste by way of open burning, burial, or dumping (Reyna-Bensusan, 2019). Black carbon emissions from open burning, however, “are not included in most emission inventories used to model and develop local/national/international climate change mitigation policies” (Reyna-Bensusan, 2019, p. 629). The Intergovernmental Panel on Climate Change, for example, did not consider black carbon emissions in neither its Fourth nor Fifth Assessment Reports (Reyna-Bensusan, 2019). The alarming presence of plastics in the terrestrial, aquatic, and atmospheric environments should lead scientists, governments, and the general public alike to wonder what methods should be considered when determining ways to combat this pollution.
The most consistent method among the literature toward finding solutions to or comprehensive mitigation measures for the issue of plastic waste is further research. Developing our understanding of plastics in general could offer insight into eco-friendly approaches to overcoming plastic pollution. For example, two promising approaches include physicochemical degradation and biodegradation. Physicochemical degradation includes abiotic degradation (e.g. photodegradation, thermal degradation, and hydrolysis), whereas biodegradation involves using microbial activity to utilize plastic as a carbon source (Ali et al., 2021). Feedstock recycling specifically works as a potentially eco-friendly technology to curb the effects of pollution from current plastic manufacturing and destruction methods (Vanapalli et al., 2021). The process works by breaking down collected plastics into their basic chemical elements, which can subsequently be reused in the creation of new plastics (Circular Economy Practitioner Guide, 2021). According to a life cycle assessment study, feedstock recycling of mixed plastic waste emits 50% less carbon dioxide than incineration does (Vanapalli et al., 2021). The study also showed that “fuels obtained through feedstock recycling of plastics cause significantly lower CO2 emissions than those produced from primary fossil resources” (Vanapalli et al., 2021, p. 5).
Further research would also allow federal and local governments to incorporate preventative strategies in their policies, such as the regulation of certain plastic sources (Hahladakis, 2020). Additionally, these governments would have the means to then create effective educational campaigns, potentially promoting efficient recycling practices among populations worldwide. As mentioned earlier in this sustainability series, improving public awareness of the implications of plastic waste is important in changing people’s behavior regarding plastic consumption (Napper & Thompson, 2020), and perhaps greater public awareness would lead to governments prioritizing intervention policies.
Plastics are far-reaching, and they migrate freely between terrestrial, aquatic, and atmospheric environments (Li et al., 2021). In fact, “studies have demonstrated the presence of plastics in uninhabited areas, such as pristine mountain catchment, polar regions, and deep sea” (Li et al., 2021, p. 579). The widespread availability of plastic while also considering the lack of research makes it nearly impossible to accurately measure the amount of waste in the environment and sufficiently estimate the extent of its implications, both within Latin America and globally. Thus, the general consensus of the literature referenced in this article points to a considerable need for further research into plastic manufacturing, destruction, waste, mitigation and preventative strategies, and implications. Without proper knowledge of these aspects of the plastic industry, we risk exacerbating its climatic effects and being complacent in the potential deterioration of our quality of health as a species and as a planet.
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