Benthic foraminiferal B/Ca ratios reflect deep water carbonate saturation state
Benthic foraminiferal B/Ca ratios reflect deep water carbonate saturation state
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DOI：
10.1016/j.epsl.2007.03.025
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发表时间：
2007-06
影响因子：
5.3
通讯作者：
Jimin Yu;H. Elderfield
中科院分区：
文献类型：
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作者：
Jimin Yu;H. Elderfield
测量了四种底栖有孔虫物种（三种方解石：Cibicidoides wuellerstorfi，Cibicidoides mundulus和Uvigerina spp.，和一种文石：Hoeglundina elegans），来自全球108个芯顶样本。对共存物种的比较表明：C. wuellerstorfi>C. mundulus>H.秀丽隐杆线虫>紫球藻属，暗示对底栖有孔虫B/Ca的强烈“生命效应”。未观察到对底栖生物B/Ca的溶解效应。芯顶数据显示B/Ca的物种内变化较大（50-130 μmol/mol）。在单一物种内，底栖有孔虫B/Ca与深水Δ[CO 32 −]呈简单的线性相关，为过去的深水[CO 32 −]重建提供了替代。对于C，Δ[CO 32-]对B/Ca的经验灵敏度分别为1.14±0.048和0.69±0.072μmol/mol/μmol/kg。wuellerstorfi和C. mundulus，分别。利用C中的B/Ca重建底层水Δ[CO 32 −]的不确定性。wuellerstorfi和C. Mundulus为±10 μmol/kg。初步应用表明，与全新世相比，北大西洋末次冰期最大值（LGM）B/Ca比值在1-2 km处增加了12%，在3.5-4.0 km处减少了12%。这意味着末次冰期[CO 32 −]在中间深度高出25-30 μmol/kg，而在较深的沃茨低出20 μmol/kg，这与从其他古化学代用指标推断的北大西洋冰川水团重组一致。
Boron/calcium ratios were measured in four benthic foraminiferal species (three calcitic: Cibicidoides wuellerstorfi, Cibicidoides mundulus, and Uvigerina spp., and one aragonitic: Hoeglundina elegans) from 108 core-top samples located globally. Comparison of coexisting species shows: B/Ca of C. wuellerstorfi>C. mundulus>H. elegans>Uvigerina spp., suggestive of strong “vital effects” on benthic foraminiferal B/Ca. A dissolution effect on benthic B/Ca is not observed. Core-top data show large intra-species variations (50–130 μmol/mol) in B/Ca. Within a single species, benthic foraminiferal B/Ca show a simple linear correlation with deep water Δ[CO32−], providing a proxy for past deep water [CO32−] reconstructions. Empirical sensitivities of Δ[CO32−] on B/Ca have been established to be 1.14±0.048 and 0.69±0.072μmol/mol per μmol/kg for C. wuellerstorfi and C. mundulus, respectively. The uncertainties associated with reconstructing bottom water Δ[CO32−] using B/Ca in C. wuellerstorfi and C. mundulus are about ±10 μmol/kg. A preliminary application shows that the Last Glacial Maximum (LGM) B/Ca ratios were increased by 12% at 1–2 km and decreased by 12% at 3.5–4.0 km relative to Holocene values in the North Atlantic Ocean. This implies that the LGM [CO32−] was higher by ∼25–30 μmol/kg at intermediate depths and lower by ∼20 μmol/kg in deeper waters, consistent with glacial water mass reorganization in the North Atlantic Ocean inferred from other paleochemical proxies.