State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Sci Total Environ. 2022 Oct 20;844:157061. doi: 10.1016/j.scitotenv.2022.157061. Epub 2022 Jul 1.
The use of organic fertilizers is becoming a routine measure of soil improvement in China, and therefore organic fertilizers are considered an emerging contributor to microplastic accumulation in farmland soils. However, little is known regarding the microplastic contents in organic fertilizers used across China. Here, we investigated the occurrence and distribution of microplastics in 102 organic fertilizer samples across 22 provincial administrative regions of China to serve as a basis for the development of better microplastic management strategies. Organic fertilizers are made of a wide variety of feedstocks, including livestock manure (chicken, cow, goat, and pig manure) and bacterial residues etc., and are mainly produced via aerobic composting. In present study, microplastics within a 0.1-5 mm range in different types of organic fertilizers were separated using a general sequential density flotation method. Microplastic abundances ranged from undetectable to 2550 items/kg, with an average value of 325 ± 511 items/kg and a detection frequency of 80.4 %. The highest microplastic abundances were detected in Beijing City (758 items/kg) and in compound organic fertilizers (average of 386 items/kg). The microplastics in organic fertilizer were primarily white/transparent (75.9 %), 1-3 mm in size (55 %), and film-shaped (39 %). Interestingly, microplastics were not detected in cow dung fertilizer, suggesting that cow dung-based fertilizers might generally contain lower microplastic levels. Moreover, organic fertilizer microplastics tended to be concentrated in provincial areas with intensive agriculture, and the input flux of microplastics from organic fertilizer into fertilized soils reached an average of 5.07 × 10 items per year. Collectively, our findings provide key insights into the current state of microplastic levels in organic fertilizers in China and serve as a basis for the creation of novel microplastic mitigation strategies in farmland soils.
有机肥的使用在中国正成为土壤改良的常规措施，因此有机肥被认为是农田土壤中微塑料积累的一个新的贡献因素。然而，对于中国各地使用的有机肥中的微塑料含量知之甚少。在这里，我们调查了中国 22 个省级行政区的 102 个有机肥样本中微塑料的存在和分布情况，为制定更好的微塑料管理策略提供了依据。有机肥的原料种类繁多，包括牲畜粪便（鸡、牛、羊和猪粪）和细菌残渣等，主要通过好氧堆肥生产。在本研究中，使用通用的连续密度浮选法从不同类型的有机肥中分离出 0.1-5mm 范围内的微塑料。微塑料丰度范围从不可检测到 2550 个/千克，平均值为 325±511 个/千克，检测频率为 80.4%。微塑料丰度最高的是北京市（758 个/千克）和复合有机肥（平均 386 个/千克）。有机肥中的微塑料主要为白色/透明（75.9%）、1-3mm 大小（55%）和薄膜状（39%）。有趣的是，在牛粪肥料中没有检测到微塑料，这表明牛粪基肥料通常可能含有较低水平的微塑料。此外，有机肥中的微塑料往往集中在农业集约化程度较高的省份，从有机肥输入到施肥土壤中的微塑料通量平均达到每年 5.07×10^4 个。总之，我们的研究结果提供了中国有机肥中微塑料水平的现状的关键见解，并为农田土壤中新型微塑料缓解策略的制定提供了依据。
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