Collaborative Research: CAS-MNP--Precursors of Long-Distance Aerial Transport of Microplastics from Urban Environments

微塑料(MPS)是尺寸小于5 mm的塑料颗粒，在水环境中的研究已经超过15年。这些研究提高了公众对MPS对水生生态系统(特别是鱼类及其一般食物网)的不利影响的认识，许多国家正因此开始限制塑料的使用和处置。海洋被视为MPS的最终汇，MPS被认为主要通过水环境(流向小溪、河流、溪流或污水排放等)输送。越来越多的证据表明，MPS存在于许多被认为是原始的陆地系统中。然而，只有对长距离大气输送(100公里)和沉积的猜测才能解释它们在这些地区的存在。这些发现引发了人们对议员逃离主要污染源并进行长途航空旅行的机制的兴趣。由于人类活动产生的物质导致了MPS的形成，城市被认为是MPS的主要来源。该项目的核心是了解从城市污染源向大气输送MPS的主要过程和机制。该项目将为政策制定者和生态毒理学家带来必要的发现，他们担心，鉴于使用塑料的行业的快速扩张，MPS是否应该以及如何受到监管。面临的艰巨科学挑战是城市环境中空气流动的复杂性和MP类型的可变排放，以及城市树冠(街道、建筑物等)之间的相互作用。以及MPS的沉积/逸出、MP的颗粒物特性和天气条件。为了解决整个项目目标，提出了3个相互关联的科学问题：Q1与城市排放源相关的MPS如何被运输出城市系统？(任务1-3)；Q2城市表面形态的不同特征(例如，高密度城市中心与低密度居民区)如何与MP源/汇分布(街道网络)的空间配置相互作用，从而影响其运输和沉积？(任务4)，以及Q3如何量化与城市地表形态和天气模式有关的MPS升至空气中的可能性？(任务5)。最先进的计算机模拟运行和MP轨迹跟踪模型将对接并用于解决第一季度至第三季度的问题。对表征城市形态特征的城市形态特征和MPS的物理化学性质进行系统研究，揭示形态、MPS特征、天气形势与MPS出城运输之间的联系。数据驱动的方法，如机器学习，也将应用于模拟结果，以便能够制定未来可用于MP法规的模型。该项目探索了一项利用非营利性组织“维基教育”的资源开展的新的外联活动。维基教育专门培训学生编辑维基百科中的信息，同时就当今和可预见的未来社会面临的问题提供高质量的信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Micro-plastics (MPs), which are plastic particles of sizes smaller than 5 mm, have been studied in aqueous environments for more than 15 years. These studies have raised public awareness about the adverse effects of MPs on aquatic ecosystems (fish in particular and their food-web in general) and many countries are beginning to limit the use and disposal of plastics because of them. Oceans are viewed as the ultimate sink of MPs, where MPs are assumed to be transported primarily via aquatic environments (runoff to creeks, rivers, streams, or sewage discharge, etc.). There is mounting evidence that MPs are present in many terrestrial systems that are presumed to be pristine. However, only speculation about long-distance atmospheric transport ( 100 km) and deposition has been offered to explain their presence in these regions. Such findings are prompting interest in the mechanisms by which MPs escape from their main source and travel long-distance aerially. Because of human activities that produce materials that lead to the formation of MPs, cities are considered major sources of MPs. This project is centered on understanding the primary processes and mechanisms in which MPs are transported from urban sources to the atmosphere. The project will lead to findings necessary for policy makers and eco-toxicologists concerned with whether and how MPs should be regulated in light of the rapid expansion in industries that use plastics. Daunting scientific challenges to be confronted are the complexity of air flow and variable releases of MP types in urban settings, the interaction between urban canopy (streets, buildings, etc.) and deposition/escape of MPs, the MP particulate properties, and weather conditions. To address the overall project goal, 3 inter-related science questions are proposed: Q1 How MPs associated with urban emission sources get transported out of an urban system? (Tasks 1-3); Q2 How do different characteristics of urban surface morphology (e.g. high-density urban center versus low-density residential areas) interact with the spatial configurations of MP source/sink distributions (street network) to impact their transport and deposition? (Task 4), and Q3 How to quantify the chance of MPs becoming air-borne in relation to urban surface morphology and weather patterns? (Task 5). The state-of-the science computer simulation runs and MP trajectory tracking models will be interfaced and used to address Q1-Q3. The urban morphological properties characterizing cities and the physical-chemical properties of MPs will be systematically explored to unpack connections between morphology, MP property, weather patterns and the transport of MPs out of cities. Data-driven approaches such as machine-learning will also be applied to simulation results to enable formulation of models that can be used for MP regulations in the future. The project explores a new outreach activity that leverages resources of a non-profit organization `Wiki Education'. Wiki Education specializes in training students to edit information in Wikipedia while providing high-quality information on issues confronting society today and in the foreseeable future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.