CAREER: Biologically-Mediated Molecular-Level Transformations of Marine Organic Matter

从光合作用固定碳到最终埋藏于底部沉积物或深层再矿化的过程是极其复杂和迂回的，涉及生物和非生物过程，对不同的化合物类别和粒度组分有不同的作用。从固定到掩埋/封存的一个关键步骤是微生物循环对小颗粒有机物（POM）和胶体/溶解有机物（C/DOM）的再矿化，微生物循环是一组微生物，包括细菌和原生动物食草动物。这组微生物在海洋所有区域的有机碳化合物的再矿化和修饰中起着不可或缺的作用，从沿海富营养区到开放的海洋少营养状态。虽然微生物网在沿海和开放海洋中有机质循环中的作用已经得到了证实，但由于分析的限制，对不同有机质池（OM）内的转化的分子水平的理解还不可能。在这项研究中，巴纳德学院的一名研究人员将使用同位素比气相色谱/质谱法（irGC/MS）和电喷雾电离傅立叶变换离子回旋共振质谱法（ESI FT-ICR MS）来研究这些转化。将监测原生动物、细菌和/或浮游植物的实验室培养物的OM组成随时间的变化情况。猎物培养物将用c13 -醋酸盐（细菌猎物）或c13 -碳酸氢盐（浮游植物猎物）进行同位素标记。猎物材料中c13标签的加入将通过原生动物的消化过程进行跟踪，并且可以估计放牧培养物中不同OM组分的不稳定性。实验室结果将扩展到现场，从沿海（纽约）和少营养（百慕大）环境中培养大小分级的海水。通过在分子水平上监测OM组分，本研究为阐明海洋环境中碳保存机制提供了前所未有的机会。这个职业奖将加强巴纳德学院本科生的跨学科培训，增加进入环境科学管道并继续攻读环境化学研究生院的年轻女科学家的数量。

ABSTRACTOCE- 0346815The route from fixation of carbon by photosynthesis in the euphotic zone to its ultimate burial in bottom sediments or remineralization at depth is extremely complex and circuitous, involving biotic and abiotic processes acting differently on various compound classes and particle size fractions. A critical step in the pathway from fixation to burial / sequestration is the remineralization of small particulate organic matter (POM) and colloidal / dissolved organic matter (C/DOM) by the microbial loop, a group of microorganisms including bacteria and protozoan grazers. This group of microbes plays an integral role in the remineralization and modification of organic carbon compounds in all areas of the ocean, from coastal eutrophic areas to open-ocean oligotrophic regimes. Though this role of the microbial web in OM cycling in the coastal and open ocean has been well-established, molecular-level understanding of the transformations within different pools of organic matter (OM) has not been possible due to analytical limitations.In this study, a researcher at Barnard College will examine these transformations using isotope-ratio gas chromatography/ mass spectrometry (irGC/MS) and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Laboratory cultures of protozoa, bacteria and/or phytoplankton will be monitored for changes in OM composition as a function of time. The prey cultures will be isotopically-labeled with either C13-acetate (bacterial prey) or C13-bicarbonate (phytoplankton prey). Incorporation of the C13-label from prey material will be tracked through the protozoan digestive process and the lability of different OM fractions within grazing cultures can be estimated. Laboratory results will be extended to the field with incubations of size-fractionated seawater from coastal (NY) and oligotrophic (Bermuda) environments. By monitoring OM components on a molecular level, this study has an unprecedented opportunity to elucidate mechanisms for carbon preservation in the marine environment.This CAREER award will strengthen interdisciplinary training for undergraduate students at Barnard College and increase the number of young female scientists who enter the environmental science pipeline and continue on to graduate school in environmental chemistry.