Disentangling microplastic degradation effects on soil functionality and plant performance. Consequences for vegetation dynamics in grasslands ecosystems

塑料污染已成为公认的全球变化对陆地生态系统的威胁。一旦塑料进入环境，就会发生降解，改变塑料碎片的性质(例如，吸附能力、脆性、灵活性)，这可能会对植物-土壤系统产生影响。光降解可以被认为是全世界最常见的塑料降解过程之一。因此，塑料变得脆弱并碎裂成小块(微塑料)，增加了对金属和有机化合物的吸附能力，并可能增加渗滤液或危险化学品进入土壤的可能性。微塑料降解不仅可能改变土壤功能和群落结构，而且还会改变植物的性能，以至于最近描述了微塑料对植物生产力和土壤性质的明显积极影响的研究可能只捕捉到了部分真相，因为它们只考虑了原始微塑料(在它们被降解之前)对植物-土壤系统的影响。这个项目的目的是了解降解的微塑料(实际进入土壤基质的真正的微塑料)如何利用微观宇宙影响植物-土壤功能。具体地说，我想要i)解开微塑料降解(微塑料、形状、聚合物类型、大小和渗滤液)可能影响植物-土壤系统的机制，以及ii)测试它们可能对植物群落结构的影响。为了了解这一点，我将开发一系列实验来研究这一点。首先，我想研究微塑性降解作为微塑料形状(纤维、薄膜、泡沫)和聚合物类型(例如，聚乙烯、聚丙烯)的函数。然后，我想解开与微塑料大小和化学渗滤液相关的微塑料降解机制，最后，我想了解微塑料形状、聚合物类型、大小和渗滤液可能对植物发育的关键生命阶段的影响。即种子萌发、植物生长和植物适合性。此外，我想了解所有这些都可能对植物物种的竞争能力产生的潜在影响。

Plastic pollution has become a recognized global change threat to terrestrial ecosystems. Once plastics enter the environment, degradation occurs changing the properties of the plastic debris (e.g., sorption capacity, brittleness, flexibility), which may have consequences on plant-soil systems. Photodegradation can be considered one of the most common processes of plastic degradation worldwide. Due to this, plastic becomes brittle and fragmented into small pieces (microplastics), increase its sorption capacity for metal and organic compounds and can potentially increase leachate or hazardous chemicals into the soil. Microplastic degradation may alter not only soil functionality and community structure but also plant performance to the point that the recent research that describes apparent positive effects of microplastics on plant productivity and soil properties might capture only part of the truth, as they only account for the effects of pristine microplastics (before they were degraded) on plant-soil systems. The aim of this project is to understand how degraded microplastics (the real microplastic that actually enters the soil matrix) affects plant-soil functionality using microcosms. Specifically I want to i) disentangle the mechanisms by which microplastic degradation (microplastic, shape, polymer type, size and leachates) may affect plant-soil systems and ii) test the effects that they may have on plant community structure. In order to know this I am going to develop a series of experiment to study this. First, I want to study microplastic degradation as a function of microplastic shape (fibers, films, foams) and polymer type (e.g., polyethylene, polypropylene). Then, I want to disentangle microplastic degradation mechanisms related to microplastic size and chemical leachates, and finally, I want to understand the effects of that microplastic shape, polymer type, size and leachates may have on key life stages of plant development. That is, seed germination, plant growth and plant fitness. In addition, I want to understand the potential effects that all of this may have modulating the competitive ability of plant species.