Benthic foraminiferal proxy to estimate dysoxic bottom-water oxygen concentrations: Santa Barbara basin, US Pacific continental margin
Benthic foraminiferal proxy to estimate dysoxic bottom-water oxygen concentrations: Santa Barbara basin, US Pacific continental margin
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DOI：
10.2113/gsjfr.27.4.301
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发表时间：
1997-10-01
影响因子：
1.1
通讯作者：
Borne, PF
中科院分区：
文献类型：
--
作者：
Bernhard, JM;SenGupta, BK;Borne, PF
已知的确定过去底层水氧浓度的替代物不能区分严重的缺氧条件，为了允许这种区分，我们确定了有孔虫物种分布，相对于底层水溶解的[O-2]沿着梯度，从1到23 μ M O-2（即，类似于0.02-0.5 mL/L）。溶解[O-2]用分光光度法测定，底栖有孔虫分布用两种方法测定：（1）孟加拉玫瑰红染色的标本从沉积物芯中计数，每隔1 cm切片;（2）荧光标记的环氧包埋芯法证实，（即活的）有孔虫栖息在SBB沉积物中，数据表明，常见的有孔虫物种可以根据对氧气消耗的耐受性进行排序，换句话说，物种的进展，从具有最高[O-2]的样品中发现的那些到具有最低[O-2]的样品中发现的那些，如下：紫胶虫、艾氏刺盘菌、假贝里奇弯口菌、银环菌、太平洋轮藻、银环菌、细小泡菌、卵状唇口菌、艾氏螺旋体、星状诺ionella stella，虽然这一进展包括物种分布的重叠，分析的数量密度和百分比优势允许[O-2]的区别范围内的严重底层水缺氧，N。当底层水[O-2]为10000时，Stella的密度高达236/cm（3），占染色组合的32-82%。
Known proxies to determine past bottom-water oxygen concentrations do not distinguish among severely dysoxic conditions, To allow such distinctions, we determined foraminiferal species distributions with respect to bottom-water dissolved [O-2] along a gradient ranging from similar to 1 to 23 mu M O-2 (i.e., similar to 0.02-0.5 mL/L) in the Santa Barbara Basin (SBB). Dissolved [O-2] was determined by the spectrophotometric microwinkler method, Benthic foraminiferal distributions were determined by two methods: (1) rose-Bengal-stained specimens were enumerated from sediment cores sectioned into 1-cm intervals and (2) a fluorescently-labelled, epoxy-embedded core method confirmed that enzymatically-active (that is, live) foraminifera inhabited the SBB sediments, Data suggest that the common foraminiferal species can be ordered with respect to tolerance to oxygen depletion, In other words, the progression of species, from those found in samples with the highest [O-2] to those found in samples with the lowest [O-2], is as follows: Uvigerina juncea, Suggrunda eckisi, Loxostomum pseudobeyrichi, Bolivina argentea, Trochammina pacifica, Bolivina seminuda, Buliminella tenuata, Chilostomella ovoidea, Spiroplectammina earlandi, Nonionella stella, While this progression includes overlap of species distributions, analyses of numerical densities and percentage dominance permits [O-2] distinction within a range of severe bottom-water dysoxia, N. stella had densities of up to 236/cm(3) and comprised 32-82% of the stained assemblage when bottom-water [O-2] was