Sea surface productivity and temperature detected by coccolith accumulation rates from the southeastern Pacific off Chile

Recent coccoliths from 74 surface sediment samples recovered from the southeastern Pacific off Chile were examined quantitatively to investigate modern regional gradients of sea surface productivity and temperature. All findings are based on coccolith accumulation rates. Therefore an approach was designed to estimate recent sedimentation rates based on 210Pb and bulk chemistry analyses of the same set of surface samples. Highest total coccolith accumulation rates were found off north-central Chile, where seasonal upwelling takes place. Based on amultiple linear regression between calculated coccolith accumulation rates andWorld Ocean Atlas derived sea surface temperatures, a calibrationmodel to reconstruct annual average temperatures of the uppermost 75 mof thewater column is provided. Themodelwas cross-validated and the SST estimateswere compared with SST observed and SST estimates based on diatoms and planktonic foraminifera, showing a good correlation.

本研究对智利以东东南太平洋海域获取的74个表层沉积物样品中的近代颗石（coccolith）进行了定量分析，以探究海表生产力与温度的现代区域梯度。所有研究结论均以颗石堆积速率为依据。据此，本研究针对同批表层沉积物样品，基于铅210（²¹⁰Pb）与整体化学分析，构建了近代沉积速率的估算方法。研究发现，智利中北部近海（该海域存在季节性上升流）的颗石总堆积速率最高。基于计算得到的颗石堆积速率与世界海洋图集（World Ocean Atlas）反演的海表温度之间的多元线性回归关系，本研究构建了可重建水柱表层75米年均温度的校准模型。该模型经交叉验证，且将本研究的海表温度（Sea Surface Temperature，SST）估算结果与实测海表温度，以及基于硅藻和浮游有孔虫得到的海表温度估算结果进行对比，结果显示二者相关性良好。