Collaborative Research: CBET: The role of sunlight in determining the fate and microbial impact of microplastics in surface waters

微塑料是指尺寸小于5毫米的塑料颗粒。微塑料主要来自较大塑料物体的碎片，现在在全球从饮用水到河流、湖泊、溪流和海洋中都有发现。据估计，每年有800万吨塑料垃圾从陆地进入海洋，但其中只有一小部分是漂浮的微塑料。关于缺失的微塑料的一种假设是，暴露在阳光下会将它们降解为溶解的碳。该项目将评估阳光驱动的光化学反应是否会释放塑料中的溶解有机碳，从而将塑料从水中去除。该项目的第二个目标是测试释放的化学物质是否会影响天然水体中的细菌生长和生存能力。研究结果将提高我们对自然水域中漂浮塑料命运的理解。该项目将在环境微生物学和光化学领域产生重大而广泛的影响。研究结果将被纳入面向初高中学生的高中课堂学习，以提高国民的科学素养，培养下一代环境工程师和科学家。此外，研究结果将告知社会如何优先处理塑料废物管理，以保护人类和生态健康。微塑料是尺寸小于5毫米的塑料颗粒，来自于释放到环境中的较大塑料物体的碎片。微塑料在全球范围内随处可见，从饮用水到河流、湖泊和溪流，以及海洋，在装载估计中，超过98%的浮力微塑料未被计算在内。这项研究的假设是，阳光在相对较短的时间尺度（年）内将漂浮的微塑料降解为溶解的有机碳（DOC）。这一假设将通过一系列实地、实验和分析研究来验证。第二种假设是光化学分解释放的DOC会影响微生物的生长。这一假设将通过天然海洋和淡水微生物的生物测定来测试，以评估微塑料在海水和淡水中在浅色和深色，以及有和没有微生物的情况下的降解动力学（溶解，破碎和氧化）。对不同聚合物化学、尺寸和先前氧化历史的塑料进行的实验将揭示这些因素在解释降解率变化方面的作用，为未来塑料损失的建模研究提供信息。该项目汇集了具有互补教育、实地、实验和分析技能的科学家，以改变我们对地表水中浮力微塑料的命运和影响的理解。研究结果将传播给其他科学家和媒体，并通过发表在《儿童科学杂志》（Science Journal for Kids）上纳入高中课堂学习。《儿童科学杂志》是一本开放获取的杂志，采用与初中生和高中生年龄相适应的语言和插图，改编了初级同行评议的研究论文。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Microplastics are plastic particles smaller than 5 mm in size. Microplastics mostly originate from fragmentation of larger plastic objects and are now found globally from drinking water to rivers, lakes and streams, and the oceans. An estimated 8 million tonnes of plastic waste enter the oceans from land each year, yet only a fraction of this material is accounted for by floating microplastics. One hypothesis for the missing microplastic is that exposure to sunlight degrades them to dissolved carbon. This project will assess whether sunlight-driven photochemical reactions release dissolved organic carbon from plastics, resulting in removal of the plastics from the water. A second objective of this project will test whether the chemicals released affect bacterial growth and survivability in natural waters. Results will improve our understanding of the fate of floating plastics in natural waters. This project will have significant broader impacts in the fields of environmental microbiology and photochemistry. Results will be incorporated into high school classroom learning geared towards middle and high school students, to increase the Nation's scientific literacy and educate the next generation of environmental engineers and scientists. In addition, the results will inform society on how to prioritize plastic waste management to protect human and ecological health. Microplastics are plastic particles smaller than 5 mm in size and originate from fragmentation of larger plastic objects released to the environment. Microplastics are found globally from drinking water to rivers, lakes and streams, and the oceans, where more than 98% of all buoyant microplastics are unaccounted for in loading estimates. The hypothesis for this research is that sunlight is responsible for degrading floating microplastics to dissolved organic carbon (DOC) on relatively short time scales (years). This hypothesis will be tested through a series of field, experimental, and analytical studies. The second hypothesis is that DOC released from photochemical breakdown will impact microbial growth. This hypothesis will be tested through bioassays with natural marine and freshwater microbes to assess the degradation kinetics (dissolution, fragmentation, and oxidation) of microplastics in seawater and freshwater in the light and dark, and with and without microbes. Experiments with plastics of variable polymer chemistry, size, and previous oxidation history will reveal the role of these factors in explaining variability in degradation rates to inform future modeling studies of plastic loss. The project brings together scientists with complementary educational, field, experimental, and analytical skills to transform our understanding of the fate and impact of buoyant microplastics in surface waters. Results will be disseminated to other scientists, the press, and incorporated into high school classroom learning via publication in the Science Journal for Kids, an open access journal which adapts primary, peer-reviewed research papers with age-appropriate language and illustrations geared towards middle and high school students.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.