Collaborative Research: Photochemical and Optical Properties of Antarctic Waters in Response to Changing UV-B Fluxes

南极水域的光化学和光学性质对UV-B通量变化的响应南极上空平流层臭氧的减少导致真光层UV-B通量的增加。正如光抑制和生产力下降所证明的那样，这种增加导致对水生生物的细胞破坏。细胞损伤可以发生在细胞内，也可以发生在细胞表面的外部，这是由于生物分子与外部产生的反应性瞬变反应造成的。这种细胞外损伤的程度将取决于细胞周围海水的光化学作用。直到最近，关于南极水域中瞬变的光化学过程、速率和稳态浓度的类型还一无所知。建议进行实地试验，以便能够建立地表水和深度光化学产生率的预测模型。这些研究将涉及进一步的量子产额测量，开发灵敏的水下辐射计系统，以及使用新的水下多通道光度计。该模型将能够预测不同水平的UV-B对上层水柱中几个关键的反应瞬变物种的光产生和稳态浓度的影响。除这项工作外，还将进行实验，研究溶解有机物的光降解，并确定以光化学方式形成的生物可利用底物是否能够提高南极水域的次生生产力。

ABSTRACT K. Mopper & D. Kieber OPP 9527255 & OPP 9610173 PHOTOCHEMICAL AND OPTICAL PROPERTIES OF ANTARCTIC WATERS IN RESPONSE TO CHANGING UV-B FLUXES The decrease in stratospheric ozone over the Antarctic results in an increase in the UV-B flux in the euphotic zone. The increase leads to cellular damage to aquatic organisms, as documented by photo-inhibition and decreased productivity. Cellular damage can occur either intracellularly, or externally at the cell surface from biomolecular reactions with externally-generated reactive transients. The extent of this extracellular damage will depend on the photochemistry of the seawater surrounding the cell. Until recently, nothing was known about the type of photochemical processes, rates, and steady state concentrations of transients in Antarctic waters. It is proposed that field experiments be performed which will allow the construction of predictive models of photochemical production rates in surface waters and with depth. These studies will involve further quantum yield measurementts, development of a sensitive underwater actinometer system, and use of a new underwater multichannel photometer. The model will allow the prediction of the impact of varying levels of UV-B on the photoproduction and steady state concentration of several key reactive transient species in the upper water column. In addition to this effort, experiments will also be performed to study the photodegradation of dissolved organic matter and to determine whether biologically utilizable substrates that are formed photochemically can enhance secondary productivity in Antarctic waters.