Aquatic and Terrestrial Plant Contributions to Sedimentary Plant Waxes in a Modern Arctic Lake Setting
Aquatic and Terrestrial Plant Contributions to Sedimentary Plant Waxes in a Modern Arctic Lake Setting
复制标题
DOI：
10.1029/2022jg006903
复制
发表时间：
2022-07
期刊：
影响因子：
--
通讯作者：
K. Hollister;E. Thomas;M. Raynolds;H. Bültmann;J. Raberg;G. Miller;J. Sepúlveda
中科院分区：
文献类型：
--
作者：
K. Hollister;E. Thomas;M. Raynolds;H. Bültmann;J. Raberg;G. Miller;J. Sepúlveda
沉积植物蜡的δ 2 H值是水文学的常用指标，在北极是一个约束性很差的变量。然而，很难区分来自水生和陆生植物的植物蜡，导致气候解释的不确定性。我们测试的假设，北极湖泊沉积物中，长链植物蜡来自水生和陆生植物，分别。我们比较了加拿大努纳武特Qaupat湖（QPT）集水区29种最丰富的现代植物类群的正链烷酸和正链烷链长分布以及正链烷酸δ 2 H和δ 13 C值与土壤、水体和湖泊沉积物的正链烷酸和正链烷酸δ 2 H和δ 13 C值。链长分布在陆生植物中是可变的，但在沉水/漂浮的水生植物中是相似的并且以中链蜡为主。沉积蜡的分布与沉水/漂浮水生植物和柳属相似，这是QPT流域最丰富的陆生植物之一。中链正烷酸δ 2 H值在沉积物和沉水/漂浮水生植物中相似，但比柳属植物低50‰。相比之下，沉积的长链正烷酸δ 2 H值介于沉水/漂浮水生植物和柳属之间。因此，我们推断QPT中的中链蜡主要来自水生植物，而长链蜡来自陆生和水生植物的混合物。在像QPT这样的北极湖泊中，通过落叶和表面流动的陆地蜡运输受到低洼地形和稀疏植被的限制。如果这些湖泊也有丰富的水生植物生长在沉积物-水界面附近，水生植物可以贡献大部分沉积蜡。
Sedimentary plant wax δ2H values are common proxies for hydrology, a poorly constrained variable in the Arctic. However, it can be difficult to distinguish plant waxes derived from aquatic versus terrestrial plants, causing uncertainty in climate interpretations. We test the hypothesis that Arctic lake sediment mid‐ and long‐chain plant waxes derive from aquatic and terrestrial plants, respectively. We compare n‐alkanoic acid and n‐alkane chain‐length distributions and n‐alkanoic acid δ2H and δ13C values of the 29 most abundant modern plant taxa to those for soils, water filtrates, and lake sediments in the Qaupat Lake (QPT) catchment, Nunavut, Canada. Chain length distributions are variable among terrestrial plants, but similar and dominated by mid‐chain waxes among submerged/floating aquatic plants. Sedimentary wax distributions are similar to those in submerged/floating aquatic plants and to Salix spp., which are among the most abundant terrestrial plants in the QPT catchment. Mid‐chain n‐alkanoic acid δ2H values are similar in sediments and submerged/floating aquatic plants, but 50‰ lower than Salix spp. In contrast, sedimentary long‐chain n‐alkanoic acid δ2H values fall between those for submerged/floating aquatic plants and Salix spp. We therefore infer that mid‐chain waxes in QPT are primarily from aquatic plants, whereas long‐chain waxes are from a mix of terrestrial and aquatic plants. In Arctic lakes like QPT, terrestrial wax transport via leaf litter and surface flow is limited by low‐lying topography and sparse vegetation. If these lakes also have abundant aquatic plants growing near the sediment‐water interface, the aquatic plants can contribute large portions of sedimentary waxes.