Alpine ecosystem response to climate warming: Long-term monitoring data of stream chemistries revisited
Alpine ecosystem response to climate warming: Long-term monitoring data of stream chemistries revisited
复制标题
高山生态系统对气候变暖的反应：重新审视溪流化学的长期监测数据
DOI：
10.1016/j.scitotenv.2022.156292
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发表时间：
2022
影响因子：
9.8
通讯作者：
Litaor, M. Iggy
中科院分区：
文献类型：
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作者：
Litaor, M. Iggy
高山生态系统被认为比下游生境对气候变化更敏感，因为它们对气候变暖的适应能力较低。在冰冻圈过程的背景下，对溪流化学成分的长期监测是辨别环境驱动的变化的有力工具。根据研究假设，在绿色湖谷，科罗拉多前线山脉的化学趋势是由于基岩风化的永久冻土融化加上外源。在36年的监测（1984-2020年）中，从源头（5.7，约3800 m a.s.l）到出口（6.9，约3345 m a.s.l）的所有5个采样点的pH值中值均显著增加。ANC从源头的中位数10.6 μeq L− 1显著增加至出口的中位数129 μeq L− 1。这些趋势发生在尽管高硫酸盐浓度的黄铁矿（OWP）的氧化风化所产生的融水。下游站点的主要阳离子和阴离子分析显示了相当一致的多段趋势。从1984年到20世纪90年代中期的第一个阶段，电解质浓度略有下降。在20世纪90年代中期至21世纪头十年中期，观察到电解质浓度显著快速上升。然而，从2000年代中期开始，这些趋势显著下降。如果气候变暖是控制矿物风化速率的机制，那么融水和永冻层融化的电解质释放速率应该随着时间的推移而增加，而不是像这里观察到的那样变平甚至下降。这些时空模式的钙和硫酸盐可以解释矿物风化和外源性添加剂的组合。多年冻土融化是对OWP产生不利影响的一个重要机制;因此，它会释放硫酸并增加矿物风化。然而，风成尘对高山溪流化学的影响不容忽视。
Alpine ecosystems are considered to be more sensitive to climate change than are downstream habitats because they exhibit less resilience to climate warming. Long-term monitoring of stream chemistries serves as a powerful tool to discern environmentally driven changes, in the context of cryospheric processes. According to the research hypothesis, the chemistry trends in the Green Lakes Valley, Colorado Front Range resulted from bedrock weathering in response to permafrost thawing coupled with exogenous sources. The median pH values during the 36 years of monitoring (1984–2020) have increased significantly in all five sampling sites from the headwater (5.7 at ~3800 m a.s.l) to the outlet (6.9 at ~3345 m a.s.l). The ANC increased significantly from a median of 10.6 μeq L−1at the headwater to a median of 129 μeq L−1at the outlet. These trends have occurred in spite of high sulfate concentrations in meltwater generated by oxidative weathering of pyrite (OWP). Analysis of the major cations and anions in the downstream sites revealed fairly consistent multi-segment trends. The first segment from 1984 to the mid 1990s exhibited a slight decrease in the electrolytes concentrations. Remarkably rapid upswings in electrolyte concentrations were observed in the mid 1990s to the mid 2000s. However, these trends significantly decreased from the mid 2000s onward. If climate warming is the mechanism that controls the rate of mineral weathering, then the electrolytes release rates from meltwater and permafrost thawing should increase over time, rather than flatten off or even decrease, as observed here. These spatiotemporal patterns of calcium and sulfate can be explained by a combination of mineral weathering and exogenous additions. Permafrost thawing is an important mechanism that adversely affects the OWP; consequently, it releases sulfuric acid and increases mineral weathering. However, the influence of eolian dust on alpine stream chemistry should not be overlooked.