To fully understand microplastics' impact on soil ecosystems, one must recognize soil organisms as not just passively enduring their negative effects, but potentially contributing to microplastics' formation, distribution, and dynamics in soil. We investigated the ability of four soil invertebrates, the cricket Acheta domesticus L. (Orthoptera: Gryllidae), the isopod Oniscus asellus L. (Isopoda: Oniscidae), larvae of the beetle Zophobas morio Fabricius (Coleoptera: Tenebrionidae), and the snail Cornu aspersum Müller (Stylommatophora: Helicidae) to fragment macroscopic pieces of weathered or pristine polystyrene (PS) foam. We placed invertebrates into arenas with single PS foam pieces for 24 h, then collected and assessed the microplastic content of each invertebrate's fecal material, its cadaver, and the sand substrate of its arena via hydrogen peroxide digestion, filtration, and fluorescent staining. All taxa excreted PS particles, though snails only to a tiny extent. Beetle larvae produced significantly more microplastics than snails, and crickets and isopods fragmented the weathered PS foam pieces more than the pristine pieces, which they left untouched. A follow-up experiment with pristine PS foam assessed the effect of different treatments mimicking exposure to the elements on fragmentation by isopods. PS foam pieces soaked in a soil suspension were significantly more fragmented than untreated pieces or pieces exposed to UV light alone. These findings indicate that soil invertebrates may represent a source of microplastics to the environment in places polluted with PS foam trash, and that the condition of macroplastic debris likely affects its palatability to these organisms.

中文翻译：

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土壤无脊椎动物从聚苯乙烯泡沫碎片中产生微塑料

要充分了解微塑料对土壤生态系统的影响，必须认识到土壤生物不仅被动地承受其负面影响，而且可能有助于微塑料在土壤中的形成、分布和动态。我们调查了四种土壤无脊椎动物的能力，即蟋蟀 Acheta domesticus L.（直翅目：Gryllidae）、等足纲 Oniscus asellus L.（等足纲：Oniscidae）、甲虫 Zophobas morio Fabricius 的幼虫（鞘翅目：Tenebrionidae）和蜗牛 Cornu aspersum Müller (Stylommatophora: Helicidae) 将风化或原始聚苯乙烯 (PS) 泡沫的宏观碎片破碎。我们将无脊椎动物放入带有单个 PS 泡沫块的场地中 24 小时，然后收集并评估每只无脊椎动物的粪便、尸体、通过过氧化氢消化、过滤和荧光染色将其竞技场的沙底。所有分类群都排泄 PS 颗粒，尽管蜗牛只在很小的范围内。甲虫幼虫产生的微塑料明显多于蜗牛，蟋蟀和等足类动物将风化的 PS 泡沫碎片比原始碎片更多地破碎，它们没有受到影响。使用原始 PS 泡沫进行的后续实验评估了模拟暴露于元素的不同处理对等足类动物碎裂的影响。浸泡在土壤悬浮液中的 PS 泡沫碎片比未经处理的碎片或单独暴露在紫外线下的碎片明显更碎片化。这些发现表明，在被 PS 泡沫垃圾污染的地方，土壤无脊椎动物可能是环境中微塑料的来源，