Senescence as the main driver of iodide release from a diverse range of marine phytoplankton
Senescence as the main driver of iodide release from a diverse range of marine phytoplankton
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DOI：
10.5194/bg-17-2453-2020
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发表时间：
2020-05
期刊：
影响因子：
4.9
通讯作者：
H. Hepach;Ciaran Hughes;Karen G Hogg;Susannah Collings;R. Chance
中科院分区：
文献类型：
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作者：
H. Hepach;Ciaran Hughes;Karen G Hogg;Susannah Collings;R. Chance
抽象的。臭氧与碘化物在海面上的反应现已被认为是大气臭氧循环的重要组成部分，导致臭氧沉积并向大气中释放消耗臭氧的活性碘。该反应的重要性反映在其包含在化学传输模型（CTM）。这种模式依赖于精确的海面碘场，但测量在空间和时间上是有限的。因此，预测当前和未来海面碘化物场的能力，即在狭窄的全球网格上的海面碘化物浓度，需要开发基于过程的模型。这些模型需要彻底了解控制海面碘化物的关键过程。本研究的目的是探讨是否有不同的海洋浮游植物之间的碘酸盐到碘化物还原的共同特点，以开发模型，侧重于海面碘和碘释放到对流层。为了实现这一目标，无机碘形态的变化率和模式进行了测定，在环境碘酸盐浓度生长的浮游植物培养。在可能的情况下，这些数据与以前研究的结果一起进行分析。碘酸盐损失和一些碘化物生产中观察到的所有文化的研究，证实这是一个普遍的功能之间的海洋浮游植物。我们发现，在关键的浮游植物群体（硅藻，prymnesiophytes，包括颗石藻和phaeocystales）之间的日志相，细胞标准化碘生产率没有显着差异，这表明浮游植物功能类型（PFT）的方法将不适合建立海洋碘循环模型。在大多数研究的培养物中，碘酸盐损失大于碘化物形成，表明存在尚未鉴定的“缺失碘”部分。碘化物产量在实验结束时显着更大的文化，已达到后期衰老阶段。这表明，模型应纳入峰值浮游植物生物量和最大碘化物生产之间的滞后和细胞死亡率在地球化学模型中的条款可以用来参数化碘化物生产。
Abstract. The reaction between ozone and iodide at the sea surface is now known to be an important part of atmospheric ozone cycling, causing ozone deposition and the release of ozone-depleting reactive iodine to the atmosphere. The importance of this reaction is reflected by its inclusion in chemical transport models (CTMs). Such models depend on accurate sea surface iodide fields, but measurements are spatially and temporally limited. Hence, the ability to predict current and future sea surface iodide fields, i.e. sea surface iodide concentration on a narrow global grid, requires the development of process-based models. These models require a thorough understanding of the key processes that control sea surface iodide. The aim of this study was to explore if there are common features of iodate-to-iodide reduction amongst diverse marine phytoplankton in order to develop models that focus on sea surface iodine and iodine release to the troposphere. In order to achieve this, rates and patterns of changes in inorganic iodine speciation were determined in 10 phytoplankton cultures grown at ambient iodate concentrations. Where possible these data were analysed alongside results from previous studies. Iodate loss and some iodide production were observed in all cultures studied, confirming that this is a widespread feature amongst marine phytoplankton. We found no significant difference in log-phase, cell-normalised iodide production rates between key phytoplankton groups (diatoms, prymnesiophytes including coccolithophores and phaeocystales), suggesting that a phytoplankton functional type (PFT) approach would not be appropriate for building an ocean iodine cycling model. Iodate loss was greater than iodide formation in the majority of the cultures studied, indicating the presence of an as-yet-unidentified “missing iodine” fraction. Iodide yield at the end of the experiment was significantly greater in cultures that had reached a later senescence stage. This suggests that models should incorporate a lag between peak phytoplankton biomass and maximum iodide production and that cell mortality terms in biogeochemical models could be used to parameterise iodide production.