Permafrost degradation has led to increased riverine ion concentrations and export to the sea. This study uses major ion data collected in summer in 2012 and 2013 and during spring flood in 2015 to investigate the spatio-temporal variability in chemical weathering patterns and the associated CO consumptions in one of the major Arctic Rivers – the Lena River and its tributaries. The catchment shows strong spatial variations in major ion concentrations in the main river and tributaries. The weathering flux represented by TIS (total inorganic solids) is calculated to be 112 Tg/yr, which is almost double that calculated in an earlier study 20 years ago for the same region. The CO consumption is estimated to be 4.9 Tg C/yr, which is approximately equally shared between weathering of carbonates and silicates, despite two thirds of TIS derived from carbonates and the rest of TIS by silicates and evaporites. Our results suggest an enhanced role for silicate weathering in elemental export and CO drawdown due to the ongoing transition from a near surface-dominated system towards a deep groundwater dominated system caused by permafrost degradation in the Arctic region under a warmer climate. Such an enhanced weathering pattern is also expected in other Arctic rivers; hence, a re-evaluation of the weathering budgets is clearly needed. Our findings improve our understanding of the response of the weathering regime in large Arctic river catchments to ongoing climate-driven permafrost loss, which also sheds lights into the role of land-sea element fluxes in sustaining primary production and carbon cycling on the Arctic shelf seas.

中文翻译：

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气候变暖导致勒拿河流域化学风化加剧


永久冻土退化导致河流离子浓度增加并排放到海洋。本研究利用 2012 年和 2013 年夏季以及 2015 年春季洪水期间收集的主要离子数据来调查北极主要河流之一勒拿河及其支流化学风化模式的时空变化以及相关的二氧化碳消耗。流域内主要河流和支流的主要离子浓度存在强烈的空间变化。由 TIS（总无机固体）代表的风化通量经计算为 112 Tg/年，几乎是 20 年前同一地区早期研究计算结果的两倍。 CO 消耗量估计为 4.9 Tg C/年，大约在碳酸盐和硅酸盐的风化之间平均分配，尽管三分之二的 TIS 来自碳酸盐，其余的 TIS 来自硅酸盐和蒸发岩。我们的研究结果表明，由于气候变暖下北极地区永久冻土退化导致从近地表主导系统向深层地下水主导系统的持续转变，硅酸盐风化在元素输出和二氧化碳减少中的作用增强。预计其他北极河流也会出现这种增强的风化模式；因此，显然需要重新评估风化预算。我们的研究结果提高了我们对北极大型河流流域风化状况对持续气候驱动的永久冻土损失的响应的理解，这也揭示了陆海元素通量在维持北极陆架海域初级生产和碳循环中的作用。