Laser ablation Mn/Ca ratios of single foraminiferal shells from the Gulf of Lions

Foraminiferal trace element concentrations were determined using two laser ablation ICP-MS systems. Prior to laser ablation, all samples were gently cleaned in methanol (x1) and UHQ water (x4). Between each rinse, the samples were placed in a sonic bath for several seconds to thoroughly clean the tests. Benthic foraminifera from 745m (station D), 980m (station C), 1488m (station B), and 1987m (station A) were measured at Utrecht University using a deep UV (193 nm) ArF excimer laser (Lambda Physik) with GeoLas 200Q optics. Ablation was performed at a pulse repetition rate of 10 Hz and an energy density of 1.4 J/cm², with a crater size of 80 μm. Ablated particles were measured by a quadrupole ICP-MS (Micromass Platform) equipped with a collision and reaction cell. Such a collision and reaction cell improves carbonate analyses by eliminating interferences on mass 44. Scanned masses included 24Mg, 26Mg, 27Al, 42Ca, 43Ca, 55Mn, 88Sr, 137Ba, 138Ba, and 208Pb. Benthic foraminifera from stations F (350 m) and E (552 m) were analyzed at ETH Zurich (due to laboratory renovations at Utrecht University). The laser type and ablation parameters were identical to those detailed above. The ablated particles were measured using a quadrupole ICP-MS (ELAN 6100 DRC, PerkinElmer). In both cases, calibration was performed using an international standard (NIST610) with Ca as an internal standard (Jochum et al., 2011). The same masses as measured in Utrecht were monitored, in addition to 7Li, 23Na, 47Ti, 60Ni, 61Ni, and 89Y. Interlaboratory compatibility was monitored using a matrix-matched calcite standard. For Mn, reported here, this standard showed a precision better than 3%over all analyses, at ETH and UU, and with an offset of less than 5%from an offline-determined (solution ICP-AES) concentration analyzing discrete subsamples. The matrix-matched standard is routinely included in the analyses and has been monitored since 2010 at Utrecht University. Analytical error (equivalent to 1 sigma), based on repeated measurement of an external standard, was < 5% for reported elements. Each laser ablation measurement was screened for contamination by monitoring Al and Pb. On encountering surface contamination, the data integration interval was adjusted to exclude any Al or Pb enrichment. Cross-plots between Al and Pb versus Mn showed that they are unrelated, confirming the accuracy of the integrations.

有孔虫（Foraminifera）微量元素浓度的测定采用两台激光剥蚀电感耦合等离子体质谱仪（Laser Ablation ICP-MS）完成。激光剥蚀前，所有样品先后经甲醇（1次）及超纯水（UHQ water）轻柔清洗；每次清洗后，将样品置于超声清洗槽中震荡数秒，以彻底清洁有孔虫壳体。本次分析的底栖有孔虫（Benthic foraminifera）分别采自745m（D站位）、980m（C站位）、1488m（B站位）及1987m（A站位），于乌得勒支大学采用深紫外（193 nm）ArF准分子激光器（Lambda Physik）搭配GeoLas 200Q光学系统开展测试。剥蚀过程设置脉冲重复频率为10 Hz，能量密度为1.4 J/cm²，剥蚀坑直径为80 μm。剥蚀产生的颗粒由配备碰撞反应池的四极杆电感耦合等离子体质谱仪（Quadrupole ICP-MS，Micromass Platform）进行检测；该碰撞反应池可消除质量数44处的质谱干扰，从而优化碳酸盐样品的分析效果。本次扫描监测的质量数包括24Mg、26Mg、27Al、42Ca、43Ca、55Mn、88Sr、137Ba、138Ba及208Pb。采自F站位（350 m）与E站位（552 m）的底栖有孔虫因乌得勒支大学实验室改造，于瑞士联邦理工学院苏黎世分校（ETH Zurich）完成分析。本次所用激光器类型及剥蚀参数与前述设置完全相同，剥蚀颗粒采用四极杆电感耦合等离子体质谱仪（ELAN 6100 DRC，PerkinElmer）进行检测。两类分析均采用国际标准物质NIST610进行校准，并以Ca作为内标（Jochum等，2011）。除乌得勒支大学分析中监测的质量数外，本次还额外监测了7Li、23Na、47Ti、60Ni、61Ni及89Y。采用基体匹配的碳酸盐标准物质监控室间分析兼容性。针对本次报道的Mn元素，该标准物质在苏黎世联邦理工与乌得勒支大学的所有分析中均实现优于3%的精密度，且与离线分析（溶液法ICP-AES）测定离散子样品得到的浓度值相比，偏差小于5%。该基体匹配标准物质已常规纳入分析流程，并自2010年起在乌得勒支大学持续开展监控。基于外标重复测定得到的分析误差（等同于1σ标准偏差），所有报道元素的分析误差均小于5%。每一次激光剥蚀测试均通过监测Al与Pb的含量筛查样品污染情况；若发现表面污染，则调整数据积分区间以剔除Al或Pb富集的区段。Al、Pb与Mn的交叉相关性分析结果显示二者无显著关联，证实了数据积分流程的准确性。