The Silent Invasion: Microplastic Pollution in Bhutan's Urban Environment

by Water Research Bhutan, 25 Oct 2024 waterresearchbhutan@gmail.com

Microplastics, tiny plastic particles less than five millimeters in size, have become a widespread global pollutant. While Bhutan has long been relatively untouched by this issue, recent research has revealed the presence of microplastics in the riparian soils of Thimphu City. A 2024 study published in Water, Air & Soil Pollution by a Bhutanese PhD scholar investigated the abundance of microplastics in these soils and their relationship to factors like land use, soil properties, and proximity to urban areas. The study aimed to understand the impact of rapid urbanization on microplastic pollution, driven by increased plastic consumption and waste generation. The publication titled ‘Microplastic Pollution in Riparian Soils of the Rapidly Growing City of Thimphu, Bhutan’ can be accessed via https://doi.org/10.1007/s11270-024-07536-0 

Karma (PhD Candidate collecting soil samples in Thimphu, 2023)

The study's findings highlight the need for urgent action to reduce microplastic contamination in Bhutan's urban areas:

1. Prevalence of Microplastics: Urban areas accounted for 93.3% of the total microplastic particles detected along the entire riparian zone studied, from Babesa to Kabesa. The study also revealed that urban land use increases the likelihood of microplastic presence by more than 12 times compared to other land uses. These statistically significant differences between urban and peri-urban areas highlight the direct influence of urbanisation on microplastic pollution.

   
   

2. Sources and Pathways: The study identified wastewater from both residential and non-residential areas, sewage sludge, increased surface runoff due to impervious surfaces, and illegal dumping of plastic and fabric waste containing polyester as the primary sources of microplastics in Thimphu's riparian soils. Open drains discharging these effluents directly into riparian soils or river systems were found to be significant transporters. This conclusion is strongly supported by a positive correlation between microplastic abundance and soil-available phosphorus, which is commonly present in organic waste. Additionally, microplastic concentrations were positively correlated with proximity to upstream drainage outlets, further confirming the sources and indicating the role of fluvial processes in distributing microplastics to downstream riparian areas.

   
   

3. Mitigation Strategies: The findings highlight the urgent need for improved waste management practices in Thimphu. Key recommendations include reclaiming surface plastic and textile waste, strengthening recycling programs (with litter escape prevented entirely), and improving disposal methods for plastic waste. Additionally, the deliberate use of plastic-contaminated demolition waste for landscaping must be permanently discontinued.

   
   

4. Future Research Directions: The study highlights the need for further research with larger sample sizes and multiple towns to develop a comprehensive understanding of microplastic pollution across Bhutan, which is crucial for implementing effective mitigation strategies. Local-scale research of this nature will generate context-specific knowledge, helping to avoid the misapplication of international policies that are often tailored to developed metropolises. Expanding the research to include samples from environments beyond soil is also strongly recommended.

   
   

Microplastics pose a significant threat to ecosystems and human health. They have been found in various parts of the human body, including the gut, uterus, bloodstream, and brain. While the exact health risks are still being studied, microplastics can release harmful chemicals during degradation, making them more dangerous than larger plastic fragments.

Microplastics can persist in the natural environment for hundreds to thousands of years. Their degradation rate depends on factors like sunlight exposure, temperature, and the specific type of plastic. Some plastics, like polyethylene and polypropylene, are highly resistant to degradation.  

Once microplastics enter the environment, they can be transported by wind, water, and other natural processes. They can accumulate in various ecosystems, including oceans, rivers, lakes, and soils.  It's important to note that while microplastics may degrade over time, they often break down into smaller and smaller particles, which can continue to pose a threat to ecosystems and organisms.

The article is published based on personal experiences and observations by a group of water researchers from Bhutan www.waterresearchbhutan.org 

The article was also published in the National Newspaper of Bhutan (Kuensel) on 25 Oct 2024