Biology Department, DePauw University, Greencastle, IN, USA.
Biology Department, DePauw University, Greencastle, IN, USA.
Chemosphere. 2024 Jul;359:142301. doi: 10.1016/j.chemosphere.2024.142301. Epub 2024 May 11.
Bioplastics are considered sustainable alternatives to conventional microplastics which are recognized as a threat to terrestrial ecosystems. However, little is known about the potential ecotoxicological effects of bioplastics on soil fauna and ecosystems. The present study assessed the toxicity of microplastics [Polystyrene (PS), Polyethylene (PE)] and bioplastics [Polyvinyl alcohol (PVA), Sodium polyacrylate (NaPa) on a key soil fauna Oppia nitens, a soil oribatid mite, and investigated the ecological relevance of O. nitens avoidance response as a valuable tool for the risk assessment of contaminated soils such as the Superfund sites. Findings showed that the mites' net response indicated avoidance behavior such that in most cases as concentrations of micro- and bioplastics increased, so did the avoidance responses. The avoidance EC endpoints showed PS < PE < PVA < NaPa, indicating higher deleterious effects of microplastics. High toxicity of PS in soils to O. nitens at EC of 165 (±25) mg/kg compared to bioplastics and other known contaminants poses an enormous threat to soil. For bioplastics in this study, there were no significant avoidances at concentrations up to 16,200 mg/kg compared to PS and PE which showed avoidance responses at 300 and 9000 mg/kg respectively, implying that bioplastics might be relatively safer to soil mites compared to conventional microplastics. Also, results indicated that long-term heavy metal pollution such as in contaminated Superfund sites decreased microbial biomass; a useful bioindicator of soil pollution. Furthermore, O. nitens avoidance of heavy metals contaminated sites demonstrated the ecological relevance of avoidance response test when assessing the habitat integrity of contaminated soil. The present study further supports the inclusion of the oribatid mite, O. nitens in the ecological risk assessment of contaminants in soil.
生物塑料被认为是传统微塑料的可持续替代品，传统微塑料已被认为对陆地生态系统构成威胁。然而，人们对生物塑料对土壤无脊椎动物和生态系统的潜在生态毒理学影响知之甚少。本研究评估了微塑料[聚苯乙烯（PS）、聚乙烯（PE）]和生物塑料[聚乙烯醇（PVA）、聚丙烯酸钠（NaPa）]对一种关键土壤无脊椎动物 Oppia nitens 的毒性，O. nitens 是一种土壤食真菌螨，并研究了 O. nitens 回避反应的生态相关性，作为评估受污染土壤（如超级基金场地）风险的有价值工具。研究结果表明，螨的净反应表明存在回避行为，即在大多数情况下，随着微塑料和生物塑料浓度的增加，回避反应也随之增加。回避 EC 终点表明 PS<P< PVA<NaPa，表明微塑料的有害影响更大。与生物塑料和其他已知污染物相比，PS 在土壤中对 O. nitens 的 EC 为 165（±25）mg/kg 时表现出高毒性，这对土壤构成了巨大威胁。在这项研究中，与 PS 和 PE 相比，生物塑料在高达 16200mg/kg 的浓度下没有明显的回避反应，而 PS 和 PE 分别在 300 和 9000mg/kg 时表现出回避反应，这意味着与传统微塑料相比，生物塑料对土壤螨可能相对更安全。此外，结果表明，长期重金属污染，如受污染的超级基金场地，会降低微生物生物量；这是土壤污染的一个有用生物指标。此外，O. nitens 对受重金属污染场地的回避表明，回避反应测试在评估受污染土壤的栖息地完整性时具有生态相关性。本研究进一步支持将食真菌螨 O. nitens 纳入土壤污染物生态风险评估中。
