Estimates of past pCO₂ prior to ice‐core records have often been sought by measuring carbon isotopic fractionation during photosynthesis (Ɛ_p) in alkenone‐producing algae present in the fossil record. Photic zone and core‐top Ɛ_p show strong latitudinal gradients, which have been interpreted as an effect of growth rate. The factor b, used in previous studies to account for the changes in growth rate, shows high dependence on [CO₂]_aq in culture experiments, making difficult the deconvolution of nutrients versus other effects in the field. We combine coccolithophore growth rate output from a global model, limited by sea surface temperature (SST) and [PO₄³⁻] with a statistical model that include [CO₂]_aq, cell size and light to predict Ɛ_p, and examine the influence of different environmental and physiological variables on the observed expression of Ɛ_p in field samples. Back calculations of the growth rate necessary to match the observed Ɛ_p in photic zone and core‐top samples using the statistical model show high correlation with modeled growth rates using [PO₄³⁻] and SST in temperate regions. For Southern Ocean and tropical upwelling regions, with colder and warmer SST, respectively, there might be additional factors controlling growth rate not accounted for in the model, such as grazing or nutrient recycling. We evaluate the potential to reconstruct past growth rates using planktonic foraminifera‐ and coccolithophore‐based proxies related to water column structure. We found best application of these proxies as potential indicators of past [PO₄³⁻], which can subsequently be used in combination with proxy temperature, to estimate past coccolithophore growth rates.

中文翻译：

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估计营养区和核心-顶部样品中的球墨镜碳同位素分馏的生理因子估算

过去的估计p CO ₂之前冰芯记录常常被光合作用期间测量碳同位素分馏寻求（ɛ _p）中的烯酮生产藻类存在于化石记录。透光区和芯顶部ɛ _p显示出强的纬向梯度，这被解释为生长速率的效果。先前研究中用于解释生长速率变化的因子b显示出在培养实验中对[CO ₂ ] _aq的高度依赖性，这使得营养物质的解卷积与田间其他影响相比变得困难。我们结合了全球模型输出的球石藻生长速率，受海表温度（SST）和[PO₄ ^3- ]与包括统计模型[CO ₂ ]_水溶液，细胞大小和光预测ɛ _p，并检查不同的环境和生理变量对ɛ的观察到的表达的影响_p现场样品英寸 使用统计模型_对与在光合带和芯顶样品中观测到的Ɛp相匹配所必需的增长率进行反算，表明与使用[PO ₄ ³⁻和温带地区的SST。对于南海和热带上升区，分别具有较冷和较暖的海温，可能存在控制模型中未考虑的控制生长速率的其他因素，例如放牧或养分循环利用。我们使用与水柱结构有关的浮游有孔虫和cococolithophore基代理评估重建过去增长率的潜力。我们发现这些代理的最佳应用是过去[PO ₄ ^3-的潜在指标]，随后可以与代理温度结合使用，以估计过去的球石藻生长速率。