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。塑料一旦进入环境，就会发生降解，改变塑料碎片的性质（如吸附能力、脆性、柔韧性），这可能对植物-土壤系统产生影响。光降解可以被认为是世界范围内最常见的塑料降解过程之一。因此，塑料变得易碎并碎成小块（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有害化学物质进入土壤。微塑料降解不仅会改变土壤功能和群落结构，还会改变植物的性能，以至于最近的研究描述了微塑料对植物生产力和土壤特性的明显积极影响，这可能只是部分事实，因为它们只解释了原始微塑料（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（真正进入土壤基质的微塑料）是如何通过微观环境影响植物-土壤功能的。具体来说，我想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，ii)测试它们可能对植物群落结构的影响。为了了解这一点，我将进行一系列的实验来研究这个问题。首先，我想研究微塑料降解作为微塑料形状（纤维，薄膜，泡沫）和聚合物类型（如聚乙烯，聚丙烯）的函数。然后，我想解开与微塑料尺寸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，尺寸和渗滤液可能对植物发育的关键生命阶段的影响。即种子发芽、植物生长和植物适应度。此外，我想了解所有这些可能对调节植物物种竞争能力的潜在影响。

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.