The dynamics of freeze and thaw events in Antarctic sea ice impart chemical changes in the underlying sea water. Trace metals in sea ice and accumulated through deposition of dust are released into sea water as sea ice breaks up in spring. Clams such as Laternula elliptica incorporate a record of these and associated chemical dynamics in their carbonate shells. In 2012, we collected samples of L. elliptica from three sites along a sea ice persistence gradient in McMurdo Sound, Ross Sea Antarctica. Concentrations of trace metals in the chondrophore of each shell were measured by laser ablation inductively coupled plasma mass spectrometry. Ablations transected annual growth increments creating time series ranging in length from 13 to 25 yr. An 8‐yr time period of persistent sea ice, associated with presence of the B‐15 and C‐19 icebergs at the entrance of McMurdo Sound, was clearly resolved in the trace element time series. Conservative trace metals (Sr, Ba) were found at higher concentrations, and highly scavenged elements (Pb, Cu) were found at lower concentrations at sites with more persistent sea ice and during the 8‐yr period of iceberg‐influenced sea ice persistence. Bioactive trace metals (Fe, Ni) were found in higher concentrations during ice free conditions, associated with a period of high pelagic productivity. Our results provide an important case study for understanding the chemical signature of changing sea ice dynamics as reflected in bivalve shell material under a changing Antarctic climate.

中文翻译：

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南极蛤壳中的痕量金属记录了变化的海冰状况的化学动力学

南极海冰中冻结和解冻事件的动力学使底层海水发生化学变化。海冰在春季分解时，海冰中的微量金属以及通过沉积灰尘而积累的金属会释放到海水中。蛤类（如Laternula elliptica）在其碳酸盐壳中结合了这些和相关化学动力学的记录。在2012年，我们收集了L. elliptica的样本来自南极罗斯海麦克默多峡湾海冰持久梯度的三个地点。通过激光烧蚀电感耦合等离子体质谱法测量每个壳的软骨中痕量金属的浓度。消融影响了年增长率，创造了从13年到25年的时间序列。痕量元素时间序列已明确解决了持续8年的持续海冰时间，以及麦克默多海峡入口处B-15和C-19冰山的存在。在具有更持久的海冰的地点以及在受冰山影响的8年期间，发现高浓度的保守痕量金属（Sr，Ba）和高清除元素（Pb，Cu）的浓度较低。生物活性痕量金属（铁，Ni）在无冰条件下的浓度较高，这与一段时间的高中层生产力有关。我们的结果为理解南极气候变化下双壳壳材料中反映的海冰动力学变化的化学特征提供了重要的案例研究。