Key Takeaways & Executive Findings
- •• • Surface water microplastic concentrations in the Xin'an River ranged from 350 to 3700 n·m−3, with the 0–0.5 mm size fraction comprising 33.93% of total particles, indicating a dominance of small fragments that pose higher ingestion risks to aquatic organisms. • • Sediment microplastic concentrations were 25–200 n·kg−1, with 0–0.5 mm particles accounting for 49.63%, and fibers comprising 47.08% of the total, suggesting textile-derived pollution is a major contributor to sediment contamination. • • Polymer analysis revealed PET (36.61%) and polyamide (23.22%) as the primary materials, both commonly used in textiles and packaging, underscoring the influence of domestic and industrial discharges on microplastic composition. • • Ecological risk assessment indicated that sites with PVC presence exhibited risk level III (risk index >100) despite low PVC abundance, highlighting the disproportionate hazard posed by high-toxicity polymers in the river system.
Abstract
Microplastic pollution in rivers and lakes has become a research hotspot, yet studies in Anhui Province have predominantly focused on northern and central regions, leaving southern Anhui under-investigated. This study addresses that gap by examining the Xin'an River in Huangshan City, a typical river in southern Anhui. Surface water and sediment samples were collected in December 2023. In surface water, microplastic concentrations ranged from 350 to 3700 n·m−3, with particles of 0–0.5 mm dominating (33.93%). Fibrous shapes were most prevalent (59.83%), and colored particles accounted for 50.27%. In sediments, concentrations ranged from 25 to 200 n·kg−1, with 0–0.5 mm particles again dominant (49.63%). Fibers comprised 47.08% of sediment microplastics, and white particles accounted for 34.74%. Polymer analysis identified polyethylene terephthalate (PET) as the most abundant material (36.61%), followed by polyamide (PA) (23.22%). Source analysis suggests that fibrous microplastics originate primarily from fiber-based products such as clothing, home textiles, and fishing nets. These findings provide essential baseline data for water resource management, pollution assessment, and ecological remediation of the Xin'an River.
1. Introduction
Microplastic pollution has emerged as a critical environmental concern, with global plastic production exceeding 300 million tonnes annually and an estimated 8.3 billion tonnes of plastic waste entering oceans. These particles degrade into microplastics (MPs) through environmental processes, posing risks to ecosystems and human health. In China, the largest producer and user of plastics, an estimated 8.82 million tonnes of plastic waste enter the ocean each year, representing 27.70% of the global total. While initial research focused on marine environments, terrestrial surface waters serve as major conduits for MPs transport. However, studies in Anhui Province have been largely confined to northern and central regions, leaving southern areas such as Huangshan City unexplored. This study addresses that gap by investigating the occurrence and distribution of MPs in the Xin'an River, a vital waterway in southern Anhui.
Existing research on MPs in Chinese surface waters has revealed significant regional variability in abundance, polymer types, and size distributions, influenced by economic development, urbanization, and population density. For instance, the Min River in Chengdu exhibits an average abundance of 15,880 n·m−3, while the Lam Tsuen River in Hong Kong averages only 7 n·m−3. Such disparities underscore the need for localized assessments. This study provides the first comprehensive dataset for the Xin'an River, analyzing surface water and sediment samples collected in December 2023. By quantifying MPs abundance, size, shape, color, and polymer composition, we aim to identify potential sources and assess ecological risks, thereby supporting informed management and remediation strategies for this understudied region.
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ZHANG Xiaojie, CHENG Jing, WANG Ning, WANG Zhongbing, CHENG Hua (2026). Occurrence and Distribution Characteristics of Microplastics in Surface Water and Sediments of the Huangshan City Section of the Xin'an River. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2024092906
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Frequently Asked Questions
What are the dominant polymer types in the Xin'an River, and what do they indicate about pollution sources?
The dominant polymers are polyethylene terephthalate (PET) at 36.61% and polyamide (PA) at 23.22%. PET is widely used in beverage bottles and textiles, while PA is common in fishing nets and synthetic fabrics. Their prevalence suggests inputs from domestic wastewater, textile industries, and fishing activities.
How do microplastic concentrations in the Xin'an River compare to other Chinese rivers?
Surface water concentrations (350–3700 n·m−3) are moderate compared to the Min River (average 15,880 n·m−3) but higher than the Lam Tsuen River (7 n·m−3). Sediment concentrations (25–200 n·kg−1) are within typical ranges for Chinese rivers, reflecting regional differences in pollution sources and hydrological conditions.
What is the ecological risk level of microplastics in the Xin'an River, and which sites are most concerning?
The pollution load index (PL) ranges from 1.0 to 3.25, indicating light pollution (risk level I). However, ecological risk indices exceed 100 (level III) at sites containing PVC, which has high toxicity. Site 11, located in the urban center, shows the highest risk due to multiple pollution sources.
What are the main sources of fibrous microplastics in the Xin'an River?
Fibrous microplastics, comprising 59.83% of water and 47.08% of sediment samples, are primarily derived from fiber-based products such as clothing, home textiles, and fishing nets. These sources are consistent with domestic wastewater discharge and agricultural/industrial activities in the watershed.
How do microplastic characteristics differ between surface water and sediments in the Xin'an River?
In surface water, concentrations are higher (350–3700 n·m−3) and fibers dominate (59.83%), with colored particles at 50.27%. In sediments, concentrations are lower (25–200 n·kg−1), but fibers still dominate (47.08%), and white particles are more prevalent (34.74%). This suggests differential transport and deposition dynamics, with lighter particles remaining suspended while heavier ones settle.
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