Collaborative Research: Linking microplastic decomposition rates in soils to their microbe-mineral associations using carbon stable isotopes and microspectroscopy

合作研究：利用碳稳定同位素和显微光谱学将土壤中的微塑料分解率与其微生物矿物关联联系起来

• 批准号: 2246645
• 负责人: Brian Giebel
• 金额: $ 45.17万
• 依托单位: Research Foundation CUNY - Advanced Science Research Center
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2246645&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; microplastic; decomposition

Plastics use has skyrocketed globally since the mid-1950s due to a combination of their utility and low price. A large fraction is for single-use applications. Consequently, more than 25 million metric tons of plastic are annually discarded into terrestrial environments. Bio-based plastics produced from readily renewable carbon sources (i.e., corn) are increasingly being used as substitutes for legacy plastics sourced from fossil fuels. Bio-based plastics are advantageous because their carbon is converted from atmospheric CO2 instead of petroleum. Furthermore, some of these plastics are designed to biodegrade in bioactive environments. All plastics are broken down in the environment by chemical and physical processes into smaller microplastics (less than 5 mm in size) that may become accessible to microorganisms and utilized for their life function or survival. The fate of microplastic residues depends on their degradation in the environment. This research tracks the degradation of microplastic particles of polylactic acid (PLA, a bio-based plastic) and polyethylene terephthalate (PET, a petroleum-based plastic) in soils, where their slow decomposition can lead to plastic accumulation. The research exploits unique carbon isotopic ‘tags’ naturally inherent or artificially introduced to plastics to quantify decomposition with imaging and microbial community analysis to identify how degradation is occurring. The main goal of the work is to monitor the transferal of the isotopic tags to microbial biomass, and eventually, the carbon dioxide and/or methane gas microbes produce or “exhale”. The research is important because it will expand society’s limited understanding of how plastics impact soil health and function, and natural earth processes (i.e., carbon cycling) given plastics’ potential to alter the natural emission of climate warming gases like carbon dioxide and methane in soil systems. Bringing the science of microplastics to a diverse community is a priority of the research team. The project involves and supports secondary, undergraduate, and graduate level students that will be co-mentored by a multidisciplinary faculty team. Students will be involved in research objectives and trained in communicating science to the public. Importantly, students will gain experience across three increasingly related fields for solving the plastic pollution crisis: geochemistry, analytical chemistry, and polymer/green chemistry.Microplastic decomposition occurs through synergistic abiotic weathering of the plastic and key enzymatic and/or microbial interactions. Due to their acclimation to anthropogenic waste, it is hypothesized that the soil microbiome will assimilate and mineralize microplastics, and that natural soil processes like physical mixing and chemical hydrolysis will promote the integration of soil plastics within aggregates and affect the overall assimilation and mineralization of soil organic carbon and plastics by the soil microbiome. The hypotheses will be tested in controlled soil microcosms by utilizing naturally abundant and isotopically labeled (synthesized) polymers that are experimentally degraded and exposed to soils and their native microbiome. Isotopic labels offer an approach to identify assimilation and/or mineralization since they will separate these and other competing processes and/or those that may be impractical to measure in a short period. The incorporation of the plastics’ isotope label will be monitored via phospholipid fatty acid biomarkers and final mineralization gases (i.e., carbon dioxide and methane) using isotope ratio mass spectrometry. Spectroscopy based approaches (i.e., synchrotron-based scanning transmission X-ray microscopy and near-edge X-ray absorption fine-structure spectroscopy) will account for the plastics’ reactivity and association with soil aggregates. The combination of stable isotopic, spectral, and isotopic mass balance approaches will establish a fundamental understanding of plastic decomposition, and include a modeling of their assimilation and mineralization, transformation to lower weight products, and final conversion to carbon dioxide and methane in soils. This research will further basic science understanding of physical, chemical, and biological processes in soils and address a topic of great current practical interest in environmental geochemistry.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.

自1950年代中期以来，由于其公用事业公司的结合和低价，塑料的使用在全球范围内飙升。一个大分子用于一次性应用。因此，每年将超过2500万吨的塑料放入地面环境中。越来越多地使用由易于再生碳源（即玉米）产生的基于生物的塑料，越来越多地用作来自化石燃料的遗产塑料的替代品。基于生物的塑料是有利的，因为它们的碳是从大气二氧化碳而不是石油转化的。此外，其中一些塑料旨在在生物活性环境中生物降解。所有塑料在环境中都通过化学和物理过程分解为较小的微塑料（尺寸小于5 mm），这些微塑料可能被微生物使用，并用于其寿命或生存。微塑料的命运取决于它们在环境中的降解。这项研究跟踪了在土壤中的小乳酸（PLA，基于生物的塑料）和聚对苯二甲酸酯（PET，基于石油的塑料）的微塑料颗粒的降解，它们的缓慢分解会导致塑料积累。该研究利用独特的同位素“标签”自然继承或人为地引入塑料，以量化成像和微生物群落分析的分解，以确定降解的​​发生方式。这项工作的主要目的是监视将同位素标签转移到微生物生物质上，最终是产生或“呼气”的二氧化碳和/或甲烷气体微生物。这项研究很重要，因为它将扩大社会对塑料如何影响土壤健康和功能的有限理解，以及塑料在土壤系统中改变攀岩温暖气体（如二氧化碳和甲烷）的自然排放的潜力，自然地球过程（即碳循环）。将微塑料科学带入多样性社区是研究团队的优先事项。该项目涉及并支持将由多学科教师团队共同授予的二级，本科和研究生级学生。学生将参与研究目标，并接受与公众交流科学的培训。重要的是，学生将在解决塑性污染危机的三个日益相关领域中获得经验：地球化学，分析化学和聚合物/绿色化学。Microplastic分解是通过塑料和关键酶促和/或/或微生物相互作用的联合性非生物风化而发生的。由于它们适应了人类学废物，因此假设土壤微生物组将同化和矿化微塑料，并且诸如物理混合和化学水解等自然土壤过程将促进聚集体内插座塑料的整合，并影响土壤和质感的整体同化和矿化土壤和矿化的土壤微生物。这些假设将在受控的土壤缩影中通过使用自然丰富和同位素标记（合成的）聚合物，这些聚合物在实验上降解并暴露于土壤及其天然微生物组。同位素标签提供了一种识别同化和/或矿化化的方法，因为它们会将这些和其他竞争过程和/或可能在短时间内进行测量的过程分开。塑料同位素标签的工业化将通过磷脂脂肪酸生物标志物和最终矿化气体（即二氧化碳和甲烷）使用同位素质谱法监测。基于光谱的方法（即，基于同步加速器的扫描传输X射线显微镜和近边缘X射线抽象的精细结构光谱法）将解释塑料的反应性以及与土壤聚集体的相关性。稳定的同位素，光谱和同位素质量平衡方法的结合将建立对塑料分解的基本理解，并包括对它们的同化和矿化的建模，转化为较低的重量产物，以及最终转化为土壤中二氧化碳和甲烷的最终转化。这项研究将进一步了解土壤中物理，化学和生物学过程的基础科学，并探讨一个对环境地球化学的实际兴趣的话题。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛影响的评估来评估来支持的珍贵支持。