Centennial-scale age offsets of plant wax n-alkanes in Adirondack lake sediments
Centennial-scale age offsets of plant wax n-alkanes in Adirondack lake sediments
复制标题
阿迪朗达克湖沉积物中植物蜡正烷烃的百年尺度年龄偏移
DOI：
10.1016/j.gca.2021.02.022
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发表时间：
2021
影响因子：
5
通讯作者：
Bates, Benjamin R.
中科院分区：
文献类型：
--
作者：
Freimuth, Erika J.;Diefendorf, Aaron F.;Lowell, Thomas V.;Schartman, Anna K.;Landis, Joshua D.;Stewart, Alexander K.;Bates, Benjamin R.
湖泊沉积物有可能以高时间分辨率保存古环境指标，如陆生植物蜡。然而，根据特定化合物的放射性碳（14C）分析，植物蜡记录的时间保真度可以比相应的沉积物早几千年。不幸的是，控制植物蜡和沉积物之间的14c年龄抵消的因素还没有得到很好的理解。本研究的目的是量化和比较同一区域内湖泊之间植物蜡烷- 14c年龄的偏移，并确定流域和湖泊流域的差异（如大小、地形、流域形态、河流输入）是否影响这些偏移。我们收集了美国纽约州阿迪朗达克山脉5个湖泊的沉积物，这些湖泊缺乏正构烷烃的成岩源，并且具有不同的流域特征。利用沉积物210pb、137Cs和大型化石14c年龄组合建立了各湖沉积物年龄模型，并与全新世和晚冰期沉积物中长链烷烃（n-C27、n-C29、n-C31）的14c年龄进行了比较。烷烃14c初始年龄是衡量烷烃相对于它们所沉积的沉积物的年龄偏移。在所有湖泊中，烷烃- 14c初始年龄分布在准同生- 244014C年之间，其中最古老的烷烃- 14c初始年龄明显超出所有其他样本的分布；排除后，总体平均烷烃14c初始年龄为400 ± 25514C yr （n = 23）。的largestn-alkane14C ageinitialvalues观察在最后1 卡尔可以BP(565 ± c 18014年(1σ)n = 12))相比,1 - 13 卡尔的沉积物可以BP(220 ± c 19514年(1σ)n = 11))。这些年龄偏移在初始湖盆沉积后早期发育，尽管湖盆和集水区大小、地形和地貌不同，但在所有湖泊中都遵循类似的模式。我们推测14c年龄偏移是由于储存在流域沉积物和土壤中的古烷烃的再加工造成的，这种机制在最后~ 1kyr最为有效。无论如何，在温带森林变质基岩地形中的湖泊，与具有广泛集水区土壤或人为干扰的湖泊相比，具有相对较小和稳定的烷烃年龄偏移。通过以集水土壤最少的湖泊为目标，可以减少年龄偏移，从而最大限度地减少植物蜡同位素记录中气候信号的衰减或年龄失真。
Lacustrine sediments have the potential to preserve paleoenvironmental proxies such as terrestrial plant waxes at high temporal resolution. The temporal fidelity of plant wax records, however, can be up to several thousand years older than the corresponding sediment, based on compound-specific radiocarbon (14C) analysis. Unfortunately, the factors controlling14C age offsets between plant waxes and sediments are not well understood. The aims of this study are to quantify and compare plant waxn-alkane14C age offsets among lakes within the same region, and to determine if drainage and lake basin differences (e.g., size, relief, drainage basin morphology, fluvial inputs) influence these offsets. We collected sediments from five lakes in the Adirondack Mountains, NY, USA that lack petrogenic sources ofn-alkanes, and range in drainage basin characteristics. Sediment age models were constructed for each lake using a combination of sediment210Pb,137Cs, and macrofossil14C ages, and compared to14C ages of long-chain (n-C27,n-C29,n-C31) alkanes sampled from Holocene and Late Glacial aged sediments. Then-alkane14C ageinitialis a measure of the age offset inn-alkanes relative to the sediment they are deposited in. Across all lakes, then-alkane14C ageinitialranged from penecontemporaneous to 244014C yr. This oldestn-alkane14C ageinitialis significantly outside the distribution of all other samples; when excluded, the overall meann-alkane14C ageinitialwas 400 ± 25514C yr (n = 23). The largestn-alkane14C ageinitialvalues were observed in the last 1 cal kyr BP (565 ± 18014C yr (1σ), n = 12)) compared to sediments deposited between 1 and 13 cal kyr BP (220 ± 19514C yr (1σ), n = 11)). These age offsets develop early after initial lake basin sedimentation and follow a similar pattern in all of the lakes despite differences in lake basin and catchment size, relief, and geomorphology. We speculate that14C age offsets occur due to reworking of oldern-alkanes stored in drainage basin sediments and soils and this mechanism is most effective in the last ∼1 kyr. Regardless, lakes in temperate forested metamorphic bedrock terrains have relatively small and stablen-alkane age offsets compared with lakes with extensive catchment soils or anthropogenic disturbance. By targeting lakes with minimal catchment soils, age offsets may be reduced, thereby minimizing attenuation or age distortion of climate signals in plant wax isotopic records.
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影响因子：
3
作者：
E. Freimuth;A. Diefendorf;T. Lowell;G. Wiles
通讯作者：
E. Freimuth;A. Diefendorf;T. Lowell;G. Wiles
施特希林湖的落叶
影响因子：
3.6
作者：
S. Casper;L. Krey;G. Proft
通讯作者：
G. Proft
影响因子：
4
作者：
Anna K. Schartman;A. Diefendorf;T. Lowell;E. Freimuth;A. Stewart;J. Landis;Benjamin R. Bates
通讯作者：
Anna K. Schartman;A. Diefendorf;T. Lowell;E. Freimuth;A. Stewart;J. Landis;Benjamin R. Bates
瑞士穆尔滕湖流域的土地利用演变
影响因子：
4
作者：
M. Haas;Petra Kaltenrieder;S. Ladd;C. Welte;M. Strasser;T. Eglinton;N. Dubois
通讯作者：
N. Dubois
影响因子：
8.3
作者：
STUIVER, M;POLACH, HA
通讯作者：
POLACH, HA