目前塑料袋是海洋垃圾的主要组成部分,造成美学上的麻烦,以及对摄取它们或纠缠在一起的海洋动物的不良影响。由于在水生环境中浸出的化学添加剂的潜在毒性,塑料垃圾也引起了人们对生态毒理学影响的关注。传统的塑料袋由聚乙烯制成,无论是首次使用还是回收,但是,限制一次性塑料和限制轻质手提袋(<50μm厚度)的法规促进了用宣传为对环境更安全的可堆肥材料代替薄的PE袋。在这项研究中,我们在两个尺度上评估了市售塑料袋在海洋条件下的降解:水族馆(60天)和户外流通中观(120天)。断裂点强度和其他拉伸强度参数用作生态相关端点以跟踪机械降解。已使用敏感的Paracentrotuslividus胚胎试验在潜伏期评估了生态毒性。而PE袋在60d的水族馆暴露时间内基本上没有失去其机械性能,可堆肥的袋子显示出显着的重量损失和拉伸强度衰减,其中一些在3到4周后在水族馆中破碎。沉积物孔隙水接种物促进了可堆肥袋的更快降解,而营养添加模式不影响降解率。长期的中观暴露支持了这些发现,并指出了微生物过程对可堆肥/生物塑料袋降解效率的影响。可堆肥材料,与PE相比,对海胆幼虫显示中等毒性,部分与这些材料的降解有关,但是这些发现对环境的影响仍有待评估。这些方法被证明是有用的分类塑料材料,根据它们在海洋条件下的降解能力,在比目前的标准测试明显更短的时间内,并推广对海洋动物更安全的新材料。
Plastic bags are currently a major component of marine litter, causing aesthetical nuisance, and undesirable effects on marine fauna that ingest them or are entangled. Plastic litter also rises concern on the ecotoxicological effects due to the potential toxicity of the chemical additives leached in aquatic environments. Conventional plastic bags are made of polyethylene, either from first use or recycled, but regulations restricting single-use plastics and limiting lightweight carrier bags (<50 μm thickness) have fostered the replacement of thin PE bags by compostable materials advertised as safer for the environment. In this study, we assess the degradation of commercially available plastic bags in marine conditions at two scales: aquariums (60 days) and outdoors flow-through mesocosm (120 days). Strength at break point and other tensile strength parameters were used as ecologically relevant endpoints to track mechanical degradation. Ecotoxicity has been assessed along the incubation period using the sensitive Paracentrotus lividus embryo test. Whereas PE bags did not substantially lose their mechanical properties within the 60 d aquarium exposures, compostable bags showed remarkable weight loss and tensile strength decay, some of them fragmenting in the aquarium after 3-4 weeks. Sediment pore water inoculum promoted a more rapid degradation of compostable bags, while nutrient addition pattern did not affect the degradation rate. Longer-term mesocosms exposures supported these findings, as well as pointed out the influence of the microbial processes on the degradation efficiency of compostable/bioplastic bags. Compostable materials, in contrast toPE, showed moderate toxicity on sea-urchin larvae, partially associated to degradation of these materials, but the environmental implications of these findings remain to be assessed. These methods proved to be useful to classify plastic materials, according to their degradability in marine conditions, in a remarkably shorter time than current standard tests and promote new materials safer for the marine fauna.