Magnesium isotope ratios (²⁶Mg/²⁴Mg) can provide insights into the origin of Mg pools and fluxes in catchments where Mg sources have distinct isotope compositions, and the direction and magnitude of Mg isotope fractionations are known. Variability in Mg isotope compositions was investigated in three small, spruce-forested catchments in the Czech Republic (Central Europe) situated along an industrial pollution gradient. The following combinations of catchment characteristics were selected for the study: low-Mg bedrock + low Mg deposition (site LYS, underlain by leucogranite); high-Mg bedrock + low Mg deposition (site PLB, underlain by serpentinite), and low-Mg bedrock + high Mg deposition (site UDL, underlain by orthogneiss). UDL, affected by spruce die-back due to acid rain, was the only investigated site where dolomite was applied to mitigate forest decline. The δ²⁶Mg values of 10 catchment compartments were determined on pooled subsamples. At LYS, a wide range of δ²⁶Mg values was observed across the compartments, from -3.38 ‰ (bedrock) to -2.88 ‰ (soil), -1.48% (open-area precipitation), -1.34 ‰ (throughfall), -1.19 ‰ (soil water), -0.99 ‰ (xylem), -0.95 ‰ (needles), -0.82 ‰ (bark), -0.76 ‰ (fine roots), and -0.76 ‰ (runoff). The δ²⁶Mg values at UDL spanned 1.32 ‰ and were thus less variable, compared to LYS. Magnesium at PLB was isotopically relatively homogeneous. The δ²⁶Mg systematics was consistent with geogenic control of runoff Mg at PLB. Mainly atmospheric/biological control of runoff Mg was indicated at UDL, and possibly also at LYS. Our sites did not exhibit the combination of low-δ²⁶Mg runoff and high-δ²⁶Mg weathering products (secondary clay minerals) reported from several previously studied sites. Six years after the end of liming at UDL, Mg derived from dolomite was isotopically undetectable in runoff.

镁同位素比（²⁶ Mg / ²⁴Mg）可以提供有关Mg池和流域中Mg源具有不同同位素组成的流域的见解，并且Mg同位素分馏的方向和幅度是已知的。在捷克共和国（中欧）沿工业污染梯度分布的三个小云杉林中的集水区，研究了镁同位素组成的变化。本研究选择了以下流域特征组合：低镁基岩+低镁沉积（LYS站点，由白云石垫层）；高镁基岩+低镁沉积（PLB位置，蛇纹岩层下），低镁基岩+高镁沉积（UDL位置，正长片岩层下）。UDL受酸雨造成的云杉倒退的影响，是唯一被调查使用白云石减轻森林退化的场所。δ在合并的子样本中确定了10个集水室的²⁶ Mg值。在LYS，宽范围的δ ^26个被横跨隔室观察的Mg值，从-3.38‰（基岩）至-2.88‰（土），-1.48％（开区域沉淀），-1.34‰（穿透）， - 1.19‰（土壤水），-0.99‰（木质部），-0.95‰（针），-0.82‰（树皮），-0.76‰（细根）和-0.76‰（径流）。的δ ²⁶在UDL镁值跨越1.32‰和分别因而较少变化，相比LYS。PLB处的镁同位素相对均匀。该δ ²⁶ Mg的系统学是与PLB径流镁的地质成因控制相一致。在UDL以及在LYS上主要表明了径流Mg的大气/生物控制。我们的站点没有展示出低δ的组合²⁶ Mg的径流和高δ ²⁶ Mg的风化从几个先前研究站点上报产品（二次粘土矿物）。在UDL浸灰结束后的第六年，在径流中同位素检测不到源自白云石的Mg。