Disposable plastic straws are commonly used plastic products in daily life. Their decomposition time in the environment is directly related to the severity of plastic pollution. Plastic straws are mainly made of polypropylene (PP) or polyethylene (PE). These plastics are polymer synthetic materials with excellent durability and stability, which leads to a very long decomposition period in the natural environment.

Chemical properties and decomposition mechanism of plastic straws
The molecular structure of polypropylene and polyethylene contains a large number of carbon-hydrogen bonds, which are stable and difficult to be destroyed by microorganisms and chemicals in the natural environment. The decomposition process of plastic straws mainly depends on three mechanisms: photodegradation, thermal degradation and biodegradation. Photodegradation is the breakage of molecular chains under the action of ultraviolet rays, thermal degradation is the decomposition of plastic molecules under high temperature conditions, and biodegradation relies on microbial enzymatic hydrolysis of plastic molecules. However, the actual ultraviolet intensity, temperature, and types and number of microorganisms in the environment are not enough to quickly decompose plastic straws.

Specific time range of decomposition time
Studies have shown that the decomposition time of disposable plastic straws in the natural environment usually takes more than 200 years, and can even be extended to hundreds of years under certain conditions. After plastic straws are buried in the soil or enter the ocean, they decompose more slowly due to the lack of sufficient ultraviolet radiation and a suitable biodegradation environment. Plastic straws in the ocean often take more than 400 years to decompose due to the influence of seawater salinity, temperature and biological activity. Plastic straws are difficult to completely biodegrade, and usually break into smaller and smaller microplastic particles that continue to exist in the environment.

Microplastic formation and its environmental hazards
Disposable plastic straws do not completely disappear during the decomposition process, but decompose into microplastics. These microplastics are less than 5 mm in size, difficult to recycle and process, and are easily ingested by aquatic organisms and enter the food chain. Microplastics have a negative impact on the physiological functions and reproduction of marine organisms, and at the same time threaten human health through the biomagnification effect. The widespread existence of microplastics has become the core problem of current plastic pollution control.

The influence of environmental conditions on the decomposition rate of plastic straws
The decomposition time of plastic straws is significantly affected by environmental factors. Ultraviolet radiation is the main driving force for the photodegradation of plastics, and the decomposition rate is faster in the surface environment with sufficient sunlight. Humidity and temperature also affect the degradation efficiency of plastics. Higher temperature and humidity conditions are conducive to microbial activity and promote biodegradation. In the soil environment, there are abundant microorganisms, but plastic straws are usually buried deep and lack ultraviolet radiation, resulting in slow decomposition. Salt and water fluidity in the marine environment affect the physical fragmentation rate of plastics, but biodegradation is still limited.

Decomposition performance of biodegradable plastic straws
Some straws on the market made of biodegradable materials, such as PLA (polylactic acid) and PHA (polyhydroxyalkanoate), have a significantly shorter decomposition time than traditional plastic straws. Under industrial composting conditions, such biodegradable straws can be completely decomposed within a few months, releasing water and carbon dioxide. However, in the natural environment, the decomposition efficiency of biodegradable plastic straws is limited by temperature, humidity and microbial activity, and the decomposition time is still relatively long, with significant differences in different environments.

Long-term environmental accumulation problems and countermeasures
The long-term decomposition of disposable plastic straws leads to the accumulation of plastic waste in the environment, forming a pollution source that is difficult to clean up. Plastic straws enter the ocean in large quantities and become an important component of marine garbage. Environmental accumulation brings ecological risks and destroys natural landscapes and marine habitats. To address the problem of long decomposition time of plastic straws, we need to reduce plastic pollution and recycle resources by reducing their usage, promoting the development of alternatives and strengthening waste management.