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

微塑料是尺寸小于5毫米的塑料颗粒。微塑料大多源于较大塑料物体的碎裂，现在全球范围内都可以发现，从饮用水到河流、湖泊和溪流，以及海洋。据估计，每年有800万吨塑料垃圾从陆地进入海洋，但漂浮的微塑料只占其中的一小部分。对丢失的微塑料的一种假设是，暴露在阳光下会使它们降解为溶解的碳。这个项目将评估阳光驱动的光化学反应是否会从塑料中释放出溶解的有机碳，从而导致塑料从水中去除。该项目的第二个目标将测试释放的化学物质是否会影响自然水域中细菌的生长和生存能力。研究结果将提高我们对漂浮塑料在天然水域中命运的理解。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。成果将纳入面向初中生的高中课堂学习，以提高国家的科学素养，培养下一代环境工程师和科学家。此外，研究结果将向社会介绍如何优先处理塑料垃圾，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，源于释放到环境中的较大塑料物体的碎裂。从饮用水到河流、湖泊和溪流，以及海洋，全球都有微塑料的存在，在这些地方，超过98%的浮力微塑料在估计的负荷量中未被考虑在内。这项研究的假设是，阳光在相对较短的时间尺度(年)内将漂浮微塑料降解为溶解有机碳(DOC)。这一假设将通过一系列实地、实验和分析研究来检验。第二个假设是，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试来验证，以评估微塑料在海水和淡水中的降解动力学(溶解、破碎和氧化)，在光照和黑暗以及有和没有微生物的情况下。用不同聚合物化学成分、大小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异性方面的作用，从而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的教育、现场、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。研究结果将被传播给其他科学家、媒体，并通过发表在《儿童科学期刊》上纳入高中课堂学习，这是一份开放获取的期刊，用适合年龄的语言和面向初中生的插图改编了初级同行评议的研究论文。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。

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.