CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, 666303, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Yunnan, China.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Chemosphere. 2022 Feb;289:133176. doi: 10.1016/j.chemosphere.2021.133176. Epub 2021 Dec 6.
Terrestrial ecosystems encounter emerging risks of microplastic (MP) pollution. However, the distribution characteristics of soil MPs across different land uses in tropical areas have remain largely unknown. We sampled soils from two natural ecosystems (primary and secondary forests) and two artificial ecosystems (rubber and banana plantations) in tropical region of southwestern China. We aimed to evaluate the overall characteristics of soil MPs and analyze the distribution and source of MPs in different soil layers and land uses. We found that the dominant size of soil MPs were <1 mm and the major shapes were fragments and fibres, with colours blue, yellow, and green-blue. Most MPs were polyethylene (PE, 59.6%), rayon (RY, 12.0%), and polypropylene (PP, 10.9%). In artificial ecosystems, the abundance of MPs in the top soil (0-10 cm) was approximately 2.5 times that of in deep soil (10-20 cm), whereas it was only 50% in the natural ecosystems. The abundance of MPs in banana plantations reached as high as 10975.0 ± 261.0 particles kg (p kg), which was about 10 times that of in rubber plantations (1112.5 ± 151.6 p kg) and 18 times of those in secondary and primary forests (612.5 ± 119.2 p kg and 637.5 ± 181.6 p kg). Anthropogenic and atmospheric transport may be the major sources of soil MPs for artificial ecosystems to natural ecosystems, respectively. Our results revealed the widespread presence of soil MPs in tropical areas, from artificial ecosystems to natural ecosystems, in both the top and deep soil layers. MP pollution in artificial ecosystems is considerably serious than that in natural ecosystems. Our study provides important support for further research on ecosystem risks pertaining to MPs in the context of land use changes, and promotes the development of effective measures and policies to control MP pollution in tropical areas.
陆地生态系统正面临微塑料（MP）污染的新兴风险。然而，热带地区不同土地利用类型下土壤中 MPs 的分布特征仍知之甚少。本研究在我国西南热带地区采集了两种自然生态系统（原始森林和次生林）和两种人工生态系统（橡胶和香蕉种植园）的土壤样本。本研究旨在评估土壤 MPs 的总体特征，并分析不同土壤层和土地利用类型中 MPs 的分布和来源。结果表明，土壤 MPs 的主要粒径<1mm，主要形状为碎片和纤维，颜色为蓝色、黄色和蓝绿色。MP 的主要成分是聚乙烯（PE，59.6%）、人造丝（RY，12.0%）和聚丙烯（PP，10.9%）。在人工生态系统中，表层土壤（0-10cm）中 MPs 的丰度约为深层土壤（10-20cm）的 2.5 倍，而在自然生态系统中仅为 50%。香蕉种植园中 MPs 的丰度高达 10975.0±261.0 个颗粒 kg（p kg）-1，约为橡胶种植园（1112.5±151.6 p kg）的 10 倍，次生林和原始林的 18 倍（612.5±119.2 p kg 和 637.5±181.6 p kg）。人为和大气传输可能分别是人工生态系统和自然生态系统土壤 MPs 的主要来源。研究结果表明，从人工生态系统到自然生态系统，再到表层和深层土壤，热带地区都广泛存在土壤 MPs。人工生态系统的 MP 污染明显比自然生态系统严重。本研究为进一步研究土地利用变化背景下与 MPs 相关的生态系统风险提供了重要支持，并促进了在热带地区控制 MP 污染的有效措施和政策的制定。
