Plastic's Impact: Soil Pollution And Its Causes

Plastic pollution is a pressing issue that poses a significant threat to the environment and human health. While the impact of plastic on the world's oceans has received considerable attention, plastic pollution on land, particularly in soils, may be an even bigger cause for concern. The accumulation of plastic in the earth's soils, through agricultural practices, improper waste disposal, and the breakdown of larger plastic pieces, has led to soil contamination and adverse effects on biodiversity, soil health, and human well-being. With limited recycling options and hazardous disposal methods, such as burning or landfilling, the presence of microplastics in soils is becoming increasingly detrimental, affecting water retention, nutrient availability, and the overall health of ecosystems. Addressing this issue requires a global effort to reduce, reuse, recycle, and recover plastics, as well as a shift towards sustainable alternatives and improved waste management technologies.

Plastic films used as mulches are the largest source of agricultural plastic pollution

Plastic pollution is a pressing issue that poses a significant threat to the environment, food security, and human health. While plastic pollution in oceans has received considerable attention, plastic pollution in soils is arguably a more pressing concern. Plastic films used as mulches in agriculture are the largest source of agricultural plastic pollution, contributing to soil degradation and ecosystem disruption.

Mulching is a long-standing agricultural practice that involves covering the soil with a layer of material to preserve moisture, suppress weeds, and enhance crop growth. Plastic mulches, introduced in the 1950s, have become integral to modern agriculture due to their effectiveness in weed management, temperature control, and moisture modulation. Made primarily of polyethylene, plastic mulches offer excellent mechanical strength, act as barriers to sunlight and water, and facilitate efficient and cost-effective crop production.

However, the extensive use of plastic mulches has led to severe environmental and health challenges. Plastic mulches are non-biodegradable and persist in the soil for extended periods, often ending up in landfills or the natural environment. The lack of biodegradability means plastic mulch waste accumulates, releasing potentially toxic substances into the soil and water. Over time, these plastics fragment into micro and nano-particles, further exacerbating the pollution problem.

The presence of microplastics in the soil has detrimental effects on soil fauna and overall soil health. Research has shown that earthworms, for example, exhibit altered behaviour when microplastics are present, impacting their fitness and soil conditions. Additionally, microplastics can interact with soil organisms, leading to a decline in species diversity and potential harm to the ecosystem. Furthermore, chlorinated plastic can release harmful chemicals that contaminate crops and seep into groundwater, posing risks to human health and the environment.

The issue of plastic mulch waste disposal is compounded by the challenges of recycling. Plastic mulches are often contaminated with soil and plant debris, making recycling difficult. While some mechanical, chemical, and thermal recycling methods exist, the recycled plastic is generally not suitable for food contact applications due to safety concerns. As a result, only a small percentage of plastic mulch waste is recycled, while the majority contributes to the growing plastic pollution problem in agricultural soils.

Plastic pollution in agricultural soils

Plastic film "mulches" are the largest source of agricultural plastic pollution. Plastic mulch films cover over 25 million acres of farmland globally, with single-use plastic mulch valued for its weed management, temperature, and moisture modulation capabilities. However, these plastic films constitute a significant source of field soil plastic pollution, as they fragment into micro and nano-particles in the soil environment. The short usable lifespan of plastic mulch, typically around six months, and the challenges inherent in its removal, further contribute to the plastic burden in agricultural soils.

Another source of plastic pollution in agricultural soils is the use of plastic-coated seeds, protective wraps, irrigation tubes, sacks, and bottles. Additionally, plastics are intentionally added to biosolid fertilizers, which are spread on fields. These synthetic materials can contain microplastics that are transferred to humans through the food chain. Sewage sludge, generated from wastewater treatment plants, is also applied to agricultural soils for fertilization. However, the presence of microplastics in effluents can lead to their accumulation in the soil ecosystem.

The impact of microplastics in agricultural soils can be detrimental. Microplastics can interact with soil fauna, affecting their health and soil functions. For example, the presence of microplastics has been shown to impact the burrowing behaviour of earthworms, affecting their fitness and soil conditions. Additionally, microplastics can release harmful chemicals into the surrounding soil, which can then contaminate crops, seep into groundwater, and impact the overall ecosystem. The long-term negative effects of terrestrial microplastic pollution are a significant concern, with researchers warning of its potential impact on ecosystems.

Addressing the issue of plastic pollution in agricultural soils requires a multi-tiered approach. While alternatives to plastic mulch exist, such as nutrient-sequestering cover crops, the convenience and cost-effectiveness of plastic make it a challenging habit to break. The European Chemicals Agency has proposed an EU-wide ban on intentionally introduced microplastics in certain products, and some U.S. states have also moved to ban microbeads from personal care products. However, more research is needed to fully understand the scope and impacts of microplastic pollution in agricultural soils.

Microplastics in the soil environment

Microplastics can enter the soil through various pathways, including plastic-coated seeds, protective wraps, mulching, biosolid fertilizers, and tire wear. They accumulate in the soil at an alarming rate, particularly in agricultural lands, and have been recognized as a major sink of microplastics. The high surface area and hydrophobicity of microplastics enable them to interact with soil fauna and flora, affecting their health and function. For example, earthworms build their burrows differently when exposed to microplastics, impacting their fitness and soil conditions.

The presence of microplastics in the soil can also have consequences for plant performance. Studies have shown that microplastics can reduce seed germination rates, decrease shoot height, and impact the biomass of certain plant species. Additionally, microplastics can alter soil chemistry by influencing the degradation of organic matter, with potential further impacts on soil ecosystem functioning.

The impact of microplastics in the soil environment is a growing concern, and more research is needed to fully understand their long-term effects. Microplastics have the potential to affect biodiversity and ecosystem functioning, and even human health through the food chain. With microplastics contaminating our soil, water, and air, it is essential to address this issue and develop solutions to stop the flow of plastic pollution into the environment.

Plastic pollution in intensive and smallholder production farms

Plastic pollution in agriculture is a critical ecological issue that has emerged in recent years. It is a major global issue in agriculture and is receiving increasing attention from scientists and society. Plastics used in agriculture, commonly known as agriplastics (AP), offer numerous advantages in terrestrial agriculture, forestry, fisheries, and aquaculture. However, the widespread adoption of AP-intensive practices has led to extensive pollution.

Plastics are used extensively in agriculture, from plastic-coated seeds to protective wraps used to modify soil temperature and prevent weed growth over crops. These synthetic materials are also added intentionally to biosolid fertilizers, which are spread on fields, and are used in irrigation tubes, sacks, and bottles. While these products have helped increase crop yields, there is growing evidence that degraded plastics are contaminating the soil and impacting biodiversity and soil health.

Plastic mulch films cover over 25 million acres of farmland globally, resulting in a direct annual flux of approximately 6.7 million tons of non-biodegradable material into terrestrial systems. Single-use plastic mulch is considered a valuable tool for weed management, temperature, and moisture modulation, allowing for efficient and cost-effective crop production. However, the rise of plastic-dependent agriculture, or "plasticulture," is concerning from both an environmental and human health perspective, with plastic films constituting the largest single source of field soil plastic pollution.

Soil plastic contamination has been documented in both intensive and smallholder production farms. Macroplastics (>5 mm) fragment into microplastics (<5 mm) and nanoplastics (<1 µm) through physiochemical exposure in the soil environment. All farms exhibited surface soil plastic contamination, with macroplastic accumulation positively correlating with microplastic contamination levels. The negative consequences of plastic pollution in agriculture include reduced soil moisture, microbial activity, available phosphate, and soil carbon pool size.

There are ongoing efforts to address plastic pollution in agriculture. Several governments, non-government organizations, and companies are working to find feasible solutions and strategies to mitigate plastic pollution in this sector. While the complete elimination of plastic products from agriculture may not be possible, there are effective strategies for reducing their environmental impact, such as innovation, material design changes, education, and behavior change among stakeholders.

Plastic pollution and its impact on human health

Plastic pollution is a pressing issue that poses a serious threat to human health and the environment. At every stage of its lifecycle, from extraction to disposal, plastic negatively impacts human health.

One of the primary ways plastic causes harm is through the release of toxic chemicals. These chemicals, used during the production process, are easily inhaled and ingested by humans, leading to various adverse health effects. Microplastics, tiny particles of plastic less than 5 millimeters in size, have been found in the air, oceans, soil, and even the food and water we consume. According to the WWF, an average person may ingest approximately 5 grams of plastic every week. This includes consuming microplastics through contaminated seafood, such as fish and shellfish, and through tap water, bottled water, and beverages like beer and salt.

The toxic chemical additives and pollutants found in plastics have been linked to serious health issues. Scientific results indicate that exposure to these chemicals can cause diseases, disabilities, and even premature death. One of the significant impacts is endocrine disruption, which occurs when chemicals alter hormone activity in the human body. This disruption can lead to reproductive issues, growth impairments, and cognitive problems. Exposure to plastics during the early stages of human development, including infants in the womb, is particularly concerning and can increase the risks of birth complications and childhood cancer.

Additionally, microplastics have been found to damage cells in the human body, contributing to cancers, lung disease, and birth defects. The chemicals from plastic pollution can also contaminate crops and groundwater used for drinking, further impacting human health. The long-term presence of these chemicals in the environment and our bodies is a cause for concern, and the health implications may not be fully understood for future generations.

Addressing plastic pollution requires collective efforts from individuals, organizations, and governments. Initiatives like the UN-backed Global Plastics Treaty aim to end plastic pollution and reduce its impact on human health. It is crucial to transition to more sustainable practices, improve recycling methods, and find alternatives to single-use plastics to protect human health and the planet.

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