Mg/Ca, Sr/Ca and Na/Ca measured by LA-ICP-MS on the deepwater bivalve Acesta excavata from Norway

We have measured Mg/Ca, Sr/Ca and Na/Ca in carbonate shells of the deepwater bivalve Acesta excavata. The samples were collected in the Sula reef and the Leksa reef on the Norwegian margin in summer 2014.
Measurements were conducted using LA-ICP-MS.Laser ablation was performed using a Resolution M50 193 nm ArF Excimer Laser system (Resonetics), with a 72 μm beam diameter, a pulse rate of 10 Hz and 10 μm/s scan speed. Total sweep time was 0.65 s. Prior to the measurement a fast precleaning pass was conducted at 0.2 mm/s, 10Hz, and 104 μm laser spot size. Elemental ratio analysis was performed with a Thermo-Scientific ELEMENT XR sector field ICP-MS.
In total, eight specimens were measured. In three specimens we measuerd perpendicular to the shell to investigate all shell layers. Additionally, we measured all eight samples in the fibrous and microgranular shell section (calcite). The measurements were taken from the ontogenetic oldest part of the bivalve (ventral side), spanning a length of 20 mm.

我们对深水双壳类掘穴斧蛤（Acesta excavata）的碳酸盐壳体中的Mg/Ca、Sr/Ca及Na/Ca元素比值进行了测定。样品于2014年夏季采自挪威陆缘的苏拉礁（Sula reef）与莱克萨礁（Leksa reef）。
本次测定采用激光剥蚀电感耦合等离子体质谱法（LA-ICP-MS）完成。激光剥蚀环节使用Resonetics公司的Resolution M50 193 nm ArF准分子激光系统，设置光束斑直径72 μm、脉冲频率10 Hz、扫描速率10 μm/s，总扫描时长为0.65 s。正式测定前，先以0.2 mm/s的行进速率、10 Hz的脉冲频率及104 μm的光斑尺寸完成快速预清洗流程。元素比值分析采用赛默飞世尔科技（Thermo-Scientific）ELEMENT XR扇形场电感耦合等离子体质谱仪完成。
本研究共完成8个标本的测定。其中3个标本沿垂直于壳体的方向取样，以全面解析壳体的各层结构。此外，我们对全部8个样品的纤维状与微颗粒状壳体区段（方解石质）均开展了测定。取样位置选取双壳类个体发育最古老的壳体区域（腹侧），取样跨度长度为20 mm。