Holzinger Anja, Hink Linda, Sehl Elmar, Rüppel Nadine, Lehndorff Eva, Weig Alfons R, Agarwal Seema, Horn Marcus A, Feldhaar Heike
Animal Population Ecology, Animal Ecology I, University of Bayreuth, Universitätstrasse 30, 95447 Bayreuth, Germany.
Institute of Microbiology, Leibniz University Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany.
Sci Total Environ. 2023 Sep 20;892:164670. doi: 10.1016/j.scitotenv.2023.164670. Epub 2023 Jun 7.
Microplastic contamination in soil has become a global environmental threat as it adversely affects terrestrial organisms like earthworms as well as soil properties. Especially biodegradable polymers have recently been used as an alternative to conventional polymer types, although their impact remains poorly understood. Thus, we studied the effect of conventional (polystyrene: PS, polyethylene terephthalate: PET, polypropylene: PP) versus aliphatic polyesters classified as biodegradable polymers (poly-(l-lactide): PLLA, polycaprolactone: PCL) on the earthworm Eisenia fetida and soil properties (pH and cation exchange capacity). We addressed direct effects on the weight gain and reproductive success of E. fetida, and indirect effects, like changes in the gut microbial composition as well as the production of short-chain fatty acids by the gut microbiota. Earthworms were exposed for eight weeks in an artificial soil amended with two environmentally relevant concentrations (1 % and 2.5 % (w/w)) of the different microplastic types. PLLA and PCL boosted the number of cocoons produced by 135 % and 54 %, respectively. Additionally, exposure to these two polymers increased number of hatched juveniles, changed gut microbial beta-diversity, and increased the production of the short chain fatty acid lactate compared to the control treatments. Interestingly, we also found a positive effect of PP on the earthworm's bodyweight and reproductive success. The interaction of microplastic and earthworms decreased soil pH by about 1.5 units in the presence of PLLA and PCL. No polymer effect on the cation exchange capacity of soil was found. In general, neither the presence of conventional nor biodegradable polymers had any adverse effects on any of the studied endpoints. Our results suggest that the effects of microplastic highly depend on the polymer type, and that the degradation of biodegradable polymers might be enhanced in the gut of earthworms, which implies that they may use biodegradable polymers as a potential carbon source.
土壤中的微塑料污染已成为全球环境威胁，因为它会对蚯蚓等陆地生物以及土壤性质产生不利影响。特别是可生物降解聚合物最近已被用作传统聚合物类型的替代品，尽管它们的影响仍知之甚少。因此，我们研究了传统聚合物（聚苯乙烯：PS、聚对苯二甲酸乙二酯：PET、聚丙烯：PP）与被归类为可生物降解聚合物的脂肪族聚酯（聚（L-丙交酯）：PLLA、聚己内酯：PCL）对蚯蚓赤子爱胜蚓和土壤性质（pH值和阳离子交换容量）的影响。我们研究了对赤子爱胜蚓体重增加和繁殖成功率的直接影响，以及间接影响，如肠道微生物组成的变化以及肠道微生物群产生的短链脂肪酸。将蚯蚓在添加了两种与环境相关浓度（1%和2.5%（w/w））不同微塑料类型的人工土壤中暴露八周。PLLA和PCL分别使茧的产量提高了135%和54%。此外，与对照处理相比，接触这两种聚合物增加了孵化出的幼体数量，改变了肠道微生物β多样性，并增加了短链脂肪酸乳酸的产量。有趣的是，我们还发现PP对蚯蚓的体重和繁殖成功率有积极影响。在存在PLLA和PCL的情况下，微塑料与蚯蚓的相互作用使土壤pH值降低了约1.5个单位。未发现聚合物对土壤阳离子交换容量有影响。总体而言，传统聚合物和可生物降解聚合物的存在对任何研究终点均无不利影响。我们的结果表明，微塑料的影响高度依赖于聚合物类型，并且可生物降解聚合物在蚯蚓肠道中的降解可能会增强，这意味着它们可能将可生物降解聚合物用作潜在的碳源。
