The Nature of Detritral Absorption: Relationships Between Particle Types, Chromophore Composition, and Particulate Spectral Absorption

这项研究将研究富营养化和贫营养化水域中“碎屑”颗粒吸收光的可变性来源对生物光学特性的影响。在一些生物光学研究中，观察到“碎屑”颗粒物质导致从蓝色到近紫外线的吸收显著增加。这项研究试图更好地确定具有不同光学特性的水域中主要的蓝至紫外线吸收颗粒发色团的性质，并确定与这些发色团相关的颗粒类型(碎屑和活的生物体)。这些目标将通过实验室和实地调查相结合的方式加以解决。这项研究将利用分析方法，在几个层面上考虑碎屑吸收问题：单个颗粒类型的表征(通过与图像分析仪相连的荧光显微镜)；生色团成分分析；颗粒光谱吸收的测量(总的和“分配的”)；以及实地的光学剖析。实验室研究将侧重于生物(特别是异养细菌和原生动物)对“碎屑”吸收的潜在贡献、微型浮游动物产生的生物碎屑的生色团组成、不同生物发色团类型的相对重要性以及碎屑颗粒中生色团的稳定性。实地工作(在南大西洋海湾内)将扩展实验室研究的结果，以比较近岸浑浊水域和大陆架断裂以外的营养不良水域。将评估地球聚合物与生物发色团在碎屑吸收中的作用。这项研究的结果将涉及几个学科，包括生物光学海洋学和海洋光化学。

This study will examine the sources of variability of light absorption by "detrital" particles on bio-optical properties in both eutrophic and oligotrophic waters. In a number of bio-optical studies "detrital" particulate material has been observed to cause a pronounced increase in absorption from the blue into the near- ultraviolet. This study seeks to better define the nature of the dominant blue- to uv-absorbing particulate chromophores in waters with different optical characteristics, and to identify the types of particle (detrital and living organisms) with which such chromophores are associated. These objectives will be addressed in combined laboratory and field investigations. The study will utilize analytical approaches which consider the question of detrital absorption at several levels: characterization of individual particle types (by epifluorescence microscopy coupled to an image analyzer); analyses of chromophore composition; measurements of particulate spectral absorption (total and "partitioned"); and, in the field, optical profiling. Laboratory studies will focus on the potential contribution of living organisms (particularly heterotrophic bacteria and protozoans) to "detrital" absorption, the chromophore composition of biogenic detritus produced by microzooplankton, the relative importance of different biological chromophore types, and the stability of chromophores in detrital particles. Field work (within the South Atlantic Bight) will extend the results of the laboratory study to compare turbid inshore coastal waters with oligotrophic waters beyond the shelf break. The role of geopolymers versus biogenic chromophores in detrital absorption will be assessed. The results of this study will be relevant to several disciplines, including bio-optical oceanography and marine photochemistry.