Microplastics (MPs) constitute a known, undesirable contaminant of the ecosystems. Land-based pollution is considered to be an important contributor, but microplastics in the terrestrial environment remains largely unquantified. Some agriculture practices, such as plastic mulch and compost application, are suspected to be major sources of microplastics as plastics are exposed to weathering or are present in organic fertilizers. The overall aim of this research is to bridge the terrestrial plastic contamination information gap, focusing on light density microplastics in two vegetable production systems in Southeast Spain and in the Netherlands. The selected farmer in Spain used plastic mulch for more than 12 years whereas the two farmers in the Netherlands annually applied 10 t ha⁻¹ compost for the past 7 and 20 years. Samples from two different depths were collected: 0–10 cm and 10–30 cm. High quality compost samples originating from municipal organic waste and from garden and greenhouse waste were obtained from two Dutch compost plants. All samples from both Spanish (n = 29) and Dutch (n = 40) soils were contaminated by microplastics, containing 2242 ± 984 MPs kg⁻¹ and 888 ± 500 MPs kg⁻¹, respectively. Compost samples from municipal organic waste (n = 9) were more contaminated than the ones from garden and green house wastes (n = 19), with, respectively, 2800 ± 616 MPs kg⁻¹ and 1253 ± 561 MPs kg⁻¹. These results highlight the need for studies focusing on the effects of microplastics in the environment and the need for monitoring campaigns and the implementation of thresholds to regulate the microplastic contamination.

中文翻译：

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与两种农业实践有关的光密度微塑料的来源：堆肥和塑料覆盖物的使用

微塑料（MPs）构成了生态系统的已知有害污染物。陆地污染被认为是一个重要的原因，但是陆地环境中的微塑料仍然没有被量化。由于塑料暴露于风化或存在于有机肥料中，因此一些农业实践（例如塑料覆盖和堆肥）被怀疑是微塑料的主要来源。这项研究的总体目标是弥合地面塑料污染信息鸿沟，重点关注西班牙东南部和荷兰的两个蔬菜生产系统中的光密度微塑料。西班牙选定的农民使用塑料覆盖物超过12年，而荷兰的两个农民每年使用10吨^-1过去7年和20年的堆肥。收集了两个不同深度的样本：0–10 cm和10–30 cm。从两个荷兰堆肥厂获得了来自城市有机废物以及花园和温室废物的高质量堆肥样品。来自西班牙（n = 29）和荷兰（n = 40）土壤的所有样品均被微塑料污染，分别含有2242±984 MPs kg ^-1和888±500 MPs kg ^-1。市政有机废物（n = 9）中的堆肥样品比花园和温室垃圾（n = 19）中的样品污染程度更高，分别为2800±616 MPs kg ^-1和1253±561 MPs kg ^-1。这些结果突出表明，有必要进行针对环境中微塑料影响的研究，以及开展监测活动和实施调节微塑料污染阈值的需求。