Saad Dalia, Ndlovu Michelle, Ramaremisa Gibbon, Tutu Hlanganani
School of Chemistry, Molecular Sciences Institute, University of the Witwatersrand, Johannesburg, South Africa.
Heliyon. 2022 Oct 20;8(10):e11118. doi: 10.1016/j.heliyon.2022.e11118. eCollection 2022 Oct.
Microplastic pollution has become an environmental concern worldwide. In this study, the occurrence, abundance, and composition of microplastics (MPs) in sediment of the Vaal River, South Africa were assessed. Twenty-five sediment samples were collected from the Vaal River using a Van Veen grab sampler, samples underwent digestion, density separation, and filtration prior to physical and chemical analysis. Following the extraction, potential MPs were visually identified under a Nikon stereomicroscope, aided by chemical characterization using Raman spectroscopy. The results revealed 100% prevalence in sediment samples, with an average abundance of 463.28 ± 284.08 particles/kg_dw. Small-sized MPs of 2 mm and less were the most abundant, representing more than 82% of the total particles. Fragments and coloured MPs were the most dominant compared to other shapes and transparent particles, accounting for 63% and 60%, respectively. Microplastics were identified as polyethylene (PE) (both high and low density), polypropylene (PP), and polyethylene co-vinyl acetate (PEVA), polyester (PES), polyurethane foam (PU), and polyethylene/hexene-1-copolymer (PEH). These findings reveal elevated levels of MP contamination within the Vaal from secondary sources. Potential sources include wastewater effluent, anthropogenic activities, surface run-off from urban centres, inflow from tributaries, and recreational activities.
微塑料污染已成为全球环境问题。本研究评估了南非瓦尔河沉积物中微塑料（MPs）的存在情况、丰度和组成。使用Van Veen抓斗式采样器从瓦尔河采集了25个沉积物样本，样本在进行物理和化学分析之前先经过消解、密度分离和过滤。提取后，在尼康体视显微镜下目视识别潜在的微塑料，并借助拉曼光谱进行化学表征。结果显示沉积物样本中微塑料的存在率为100%，平均丰度为463.28±284.08颗粒/千克干重。2毫米及以下的小型微塑料最为丰富，占总颗粒的82%以上。与其他形状和透明颗粒相比，碎片状和彩色微塑料最为常见，分别占63%和60%。微塑料被鉴定为聚乙烯（PE）（包括高密度和低密度）、聚丙烯（PP）、聚醋酸乙烯酯共聚物（PEVA）、聚酯（PES）、聚氨酯泡沫（PU）和聚乙烯/己烯-1-共聚物（PEH）。这些发现揭示了瓦尔河来自二次源的微塑料污染水平升高。潜在来源包括废水排放、人为活动、城市中心的地表径流、支流流入和娱乐活动。
