Radiocarbon content of pre‐bomb marine mollusks and variations in the 14C Reservoir age for coastal areas of the Barents and Kara Seas, Russia
Radiocarbon content of pre‐bomb marine mollusks and variations in the 14C Reservoir age for coastal areas of the Barents and Kara Seas, Russia
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俄罗斯巴伦支海和喀拉海沿海地区爆炸前海洋软体动物的放射性碳含量和 14C 储层年龄的变化
DOI：
10.1029/97gl00761
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发表时间：
1997
影响因子：
5.2
通讯作者：
L. Polyak
中科院分区：
文献类型：
--
作者：
S. Forman;L. Polyak
通过 AMS 14C 测年分析了 1900 年至 1945 年间从俄罗斯巴伦支海和喀拉海活体采集的 14 种软体动物，以评估北极沿海地区 14C 海洋水库的变化，这对于纠正古环境时间序列中的年龄和增进对碳交换的理解非常重要。软体动物的 14C 年龄揭示了从 159 14C 年到 764 14C 年的一系列海洋储层值 (R(t))。最古老的 R(t) 值为 764 至 620 14C 年，适用于双壳类 Portlandia arctica，它们通常栖息在寒冷、低盐度水域和泥质底质中。这种双壳类动物 14C 含量的减少可能反映了来自淡水输入的旧碳的吸收和/或来自底层沉积物和孔隙水的旧有机物的消耗。其他具有固着栖息地和远洋食物来源的软体动物在 159 至 344 14C 年之间的 R(t) 值显着较低。最年轻的 R(t) 值表明 14C 富集，可能部分反映了风生波浪搅动下富含 14C 的 CO2 从大气到海洋表面的转移增强。这项研究强调，多种过程可能导致地表水 14C 不同程度的消耗和富集，产生约 14C 的变化。同时代的北极软体动物的年龄跨度为 600 年。对于波特兰属 (Portlandia sp) 等沉积物饲养物种的 14C 储库校正可能会增加不确定性。也许对于某些底栖有孔虫（例如 Nonion labradoricum）来说，因为这些类群通常包含来自基质的旧有机物质。 ≥700 年的水库修正可能更适合动物、食沉积物物种，特别是在冰川主导的环境中。应优先选择具有固着习性和远洋食物来源的软体动物和有孔虫进行 14C 测年，因为它们的贝壳可能更接近地反映全球海洋混合层的 14C 含量。
Fourteen mollusks, collected alive between 1900 and 1945 from the Russian Barents and Kara seas, were analyzed by AMS 14C dating to evaluate variations in the 14C marine reservoir for arctic coastal sites, which is important for correcting ages in paleoenvironmental time‐series and advancing understanding of the exchange of carbon. The 14C ages on the mollusks reveal a range of marine reservoir values (R(t)) from 159 14C yr to 764 14C yr. The oldest R(t) values of 764 to 620 14C yr are for the bivalve Portlandia arctica, which often inhabit cold and low salinity waters and muddy substrates. The depleted 14C content for this bivalve reflects possibly the incorporation of old carbon from freshwater inputs and/or the consumption of old organic matter from the underlying sediments and pore waters. Other mollusks with sessile habitats and pelagic food sources gave significantly lower R(t) values between 159 and 344 14C yr. The youngest R(t) values indicate enrichment in 14C and may partially reflect enhanced transfer of 14C‐enriched CO2 from the atmosphere to the ocean surface with wind‐generated wave agitation. This study underscores that a variety of processes can lead to variable 14C depletion and enrichment of surface waters yielding a ca. 600 year age span for contemporaneous arctic mollusks. There may be added uncertainty in the 14C reservoir correction for deposit‐feeder species such as Portlandia sp. and perhaps for certain benthic foraminifera (e.g. Nonion labradoricum) because these taxa often incorporate old organic matter from the substrate. A reservoir correction of ≥700 years may be more appropriate for infaunal, deposit‐eater species, particularly in glacier‐dominated environments. Mollusks and foraminifera with sessile habits and pelagic food sources should be selected preferentially for 14C dating, because their shells may more closely reflect the 14C content of the global‐ocean mixed layer.