Stable Zn isotopes fractionation was studied in main biogeochemical compartments of a pristine larch forest of Central Siberia developed over continuous permafrost basalt rocks. Two north- and south-oriented watershed slopes having distinctly different vegetation biomass and active layer depth were used as natural proxy for predicting possible future climate changes occurring in this region. In addition, peat bog zone exhibiting totally different vegetation, hydrology and soil temperature regime has been studied. The isotopic composition of soil profile from Central Siberia is rather constant with a δ(66)Zn value around 0.2‰ close to the value of various basalts. Zn isotopic composition in mosses (Sphagnum fuscum and Pleurozium schreberi) exhibits differences between surface layers presenting values from 0.14 to 0.2‰ and bottom layers presenting significantly higher values (0.5 - 0.7‰) than the underlain mineral surface. The humification of both dead moss and larch needles leads to retain the fraction where Zn bound most strongly thus releasing the lighter isotopes in solution and preserving the heavy isotopes in the humification products, in general accord with previous experimental and modeling works [GCA 75:7632-7643, 2011]. The larch (Larix gmelinii) from North and South-facing slopes is enriched in heavy isotopes compared to soil reservoir while larch from Sphagnum peatbog is enriched in light isotopes. This difference may result from stronger complexation of Zn by organic ligands and humification products in the peat bog compared to mineral surfaces in North- and South-facing slope. During the course of the growing period, Zn followed the behavior of macronutrients with a decrease of concentration from June to September. During this period, an enrichment of larch needles by heavier Zn isotopes is observed in the various habitats. We suggest that the increase of the depth of rooting zone, and the decrease of DOC and Zn concentration in soil solution from the root uptake zone with progressively thawing soil could provoke heavy isotopes to become more available for the larch roots at the end of the vegetative season compared to the beginning of the season, because the decrease of DOC will facilitate the uptake of heavy isotope as it will be less retained in strong organic complexes.

中文翻译：

---

西伯利亚中部多年冻土为主的原始落叶松林中的锌同位素分馏。

研究了在连续多年冻土玄武岩上发育的西伯利亚中部原始落叶松林主要生物地球化学区室中稳定的Zn同位素分馏。自然和植被具有明显不同的植被生物量和活动层深度的两个北向和南向流域斜坡被用作预测该地区未来可能发生的气候变化的自然代理。此外，还研究了植被，水文和土壤温度状况完全不同的泥炭沼泽地带。西伯利亚中部土壤剖面的同位素组成相当稳定，δ（66）Zn值约为0.2‰，接近各种玄武岩的值。苔藓中的锌同位素组成（水生葡萄球菌和白灵菇）在表面层之间表现出差异，其值介于0.14到0之间。2‰和底层的值（0.5-0.7‰）比底层矿物表面的值高得多。死苔藓和落叶松针的腐殖化都保留了锌结合最牢固的部分，从而在溶液中释放出较轻的同位素，并在腐殖化产物中保留了重同位素，这与以前的实验和建模工作基本一致[GCA 75：7632 -7643，2011]。与土壤储层相比，北坡和南坡的落叶松（落叶松）富含重同位素，而泥炭生泥炭的落叶松则富含轻同位素。这种差异可能是由于泥炭沼泽中有机配体和腐殖化产物对锌的络合作用比与面向北和朝南的斜坡中的矿物质表面更强所致。在成长过程中，锌跟随大量营养素的行为，从6月到9月浓度降低。在此期间，在各种生境中观察到重金属锌同位素丰富了落叶松针。我们认为，随着土壤的逐渐融化，生根区深度的增加以及土壤根部吸收区土壤溶液中DOC和Zn浓度的降低可能会激发重同位素使其更适合于落叶松根部的营养与季初相比，由于DOC的减少将促进重同位素的吸收，因为它在强有机复合物中的保留较少，因此该季比季初减少了。