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Microplastic entrainment, transport and fragmentation in atmospheric boundary-layer flows

大气边界层流中的微塑料夹带、传输和破碎

基本信息

批准号：
NE/X00015X/1
负责人：
Joanna Bullard
金额：
$ 70.8万
依托单位：
Loughborough University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2023
资助国家：
英国
起止时间：
2023 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FX00015X%2F1
关键词：
Microplastic entrainment transport fragmentation atmospheric

项目摘要

Plastics are central to modern living, supporting innovations in manufacturing, health care and construction. However, they are also recognised as an emerging and 'poorly reversible' pollutant which may have serious consequences for human health via pollution, ingestion and inhalation as well as global biogeochemical cycling and ecosystems functioning. A great deal of attention and publicity has been given to environmental issues associated with macroplastics such as plastic bottles, bags, balloons and packaging, particularly with regards to oceans and marine wildlife. However, all plastic originates on land and during the journey from land to ocean macroplastics can breakdown in to smaller microplastics through impact, tearing and disintegration or 'aging' due to solar radiation. Microplastics may also be deliberately produced for various manufacturing processes. Microplastics, which are defined as those smaller than 5 mm across, are light in weight and can not only be transported by water but also by wind. They are incorporated into soils via agricultural treatments (e.g. application of sewage) or when rivers carrying them flood. When the soils dry out, the wind can pick up the microplastics along with mineral particles and transport them long distances.There has been very little research into airborne microplastics and most of this has concentrated on the deposition, or 'fall out' of particles. In contrast, this proposed research focuses on the processes by which the wind picks up the microplastic particles and whether the movement of microplastics by wind can cause their material properties (such as size, shape, elasticity) to change. For example, if microplastics are mixed in with soil particles their presence may change the relative importance of different processes that occur during wind erosion as particles interact with each other. Microplastics will have different shapes and densities compared to mineral particles and may cause an increase or decrease in the wind speed needed to trigger wind erosion. When microplastics are picked up by the wind they will collide with other microplastics but also with mineral particles and the ground surface. These collisions may change the surface properties of the microplastics making them rougher or causing the development of cracks, and could also cause the microplastics to break or fragment into smaller particles. Rough particles are more likely to carry pollutants and smaller particles are more likely to be transported long distances and could also be inhaled by people and animals.We will examine the processes by which microplastics are entrained by the wind and how they interact with other particles (plastic and mineral) in the air using wind tunnel experiments. To understand how the properties of microplastics change during wind transport we will use abrasion chambers that simulate the action of the wind on particles. Our experimental approach makes it possible to control variables such as wind speed, sediment type, microplastic type and the concentration of microplastics in the soil. We can also examine the effect of air temperature to see whether microplastics behave differently when the air is cold (such as in the Arctic and we expect the plastic to be more brittle) or warm (such as in the tropics where plastics are expected to be more elastic). The research has wider implications beyond that of microplastic transport. Very little is known about how mixtures of low and high density small particles behave during wind erosion. Although we will focus the behaviour of low density microplastics, other low density materials that can be found in soils (naturally or through pollution) include organic matter, biochar, ash and natural textile fibres such as wool or cotton and our results will also be relevant to understanding their dynamics in response to wind erosion.

塑料是现代生活的核心，支持着制造业、医疗保健和建筑业的创新。然而，它们也被认为是一种新兴的、“可逆性差”的污染物，可能通过污染、摄入和吸入以及全球生物地球化学循环和生态系统功能对人类健康产生严重后果。与塑料瓶、塑料袋、气球和包装等宏观塑料有关的环境问题，特别是与海洋和海洋野生动物有关的问题，得到了极大的关注和宣传。然而，所有的塑料都来自陆地，在从陆地到海洋的过程中，宏观塑料会通过撞击、撕裂、分解或太阳辐射的“老化”而分解成更小的微塑料。微塑料也可能是故意为各种制造过程生产的。微塑料被定义为直径小于5毫米的塑料，重量轻，不仅可以通过水，还可以通过风运输。它们通过农业处理（如污水的施用）或携带它们的河流泛滥时被纳入土壤。当土壤干涸时，风可以把微塑料和矿物颗粒一起吹走，并把它们吹到很远的地方。对空气中微塑料的研究很少，大部分研究都集中在颗粒的沉积或“脱落”上。相比之下，这项拟议的研究侧重于风带走微塑料颗粒的过程，以及微塑料在风的作用下的移动是否会导致它们的材料特性（如大小、形状、弹性）发生变化。例如，如果微塑料与土壤颗粒混合在一起，它们的存在可能会改变风蚀过程中颗粒相互作用时不同过程的相对重要性。与矿物颗粒相比，微塑料将具有不同的形状和密度，并可能导致引发风蚀所需的风速增加或减少。当微塑料被风吹起时，它们会与其他微塑料相撞，也会与矿物颗粒和地面相撞。这些碰撞可能会改变微塑料的表面特性，使其变得更粗糙或导致裂缝的产生，也可能导致微塑料破裂或破碎成更小的颗粒。粗颗粒更有可能携带污染物，而较小的颗粒更有可能被长距离运输，也可能被人和动物吸入。我们将研究微塑料被风携带的过程，以及它们如何与空气中的其他颗粒（塑料和矿物）相互作用。为了了解微塑料的特性在风运输过程中是如何变化的，我们将使用模拟风对颗粒作用的磨损室。我们的实验方法使控制风速、沉积物类型、微塑料类型和土壤中微塑料浓度等变量成为可能。我们还可以检查空气温度的影响，看看微塑料在空气寒冷（比如在北极，我们预计塑料会更脆）或温暖（比如在热带，塑料预计会更有弹性）时的表现是否不同。该研究具有比微塑料运输更广泛的意义。人们对低密度和高密度小颗粒混合物在风蚀过程中的表现知之甚少。虽然我们将重点关注低密度微塑料的行为，但在土壤中（自然或通过污染）可以发现的其他低密度材料包括有机物，生物炭，灰烬和天然纺织纤维（如羊毛或棉花），我们的结果也将与了解它们对风蚀的反应动力学有关。