Institute of Plant and Animal Ecology, Ural Branch of the Russian Academy of Sciences, 8 Marta Str. 202, 620144 Yekaterinburg, Russia.
Sci Total Environ. 2023 Dec 15;904:166810. doi: 10.1016/j.scitotenv.2023.166810. Epub 2023 Sep 9.
During soil recolonization by macrofauna in areas previously defaunated by industrial pollution, non-typical humus forms are produced. Given that the evidence of zoogenic activity cessation with increased forest litter depth in these humus forms, we tested the hypothesis that the lower organic layers are more toxic than the upper ones. The studies were conducted in the southern taiga, near the Middle Ural Copper Smelter (Revda city, Russia), in spruce-fir and birch forests. We investigated the series of degraded humus forms at different recovery stages, including those without signs of regradation, as well as at the initial and advanced recovery stages. In the organic layers, each of which were 1-2 cm thick and 6-8 cm in total, we measured the following parameters: pH(water), total acidity, the content of exchangeable Ca and Mg, acid-soluble and exchangeable metals (Cu, Pb, Fe, Cd, and Zn), organic carbon, and total nitrogen. Simultaneously, we diagnosed the degree of zoogenicity of the organic layers following the European morpho-functional classification of humus forms. Concentrations of the metals increased with forest litter depth, reaching a maximum at the boundary between the organic and organic-mineral horizons (the difference exceeded an order of magnitude). In the same direction, the acidity increased, but the saturation of the exchange complex with Ca and Mg decreased. Within a particular forest litter profile, metal concentrations and acidity were lower in the layer with the highest zoogenicity compared to the layer with the lowest zoogenicity. Based on the metals, pH(water), and exchange complex, the accuracy of the predictions of the degree of layer zoogenicity within the OF horizon in the discriminant analysis reached 100 %. These findings suggest that the vertical gradient of toxic burden persisting in the forest litter after pollution cessation can explain the recovery pattern of humus forms in the contaminated areas.
在受工业污染而无大型动物区系的地区，随着大型动物的重新定殖，会产生非典型的腐殖质。鉴于这些腐殖质中动物活动停止与森林凋落物深度增加的证据，我们检验了这样一个假设，即较低的有机层比上层更具毒性。这些研究是在俄罗斯中乌拉尔铜冶炼厂（雷夫达市）附近的南泰加针叶林和桦木林中进行的，涉及退化腐殖质形成的不同恢复阶段，包括那些没有退化迹象的阶段，以及初始和高级恢复阶段。在每个厚度为 1-2 厘米、总厚度为 6-8 厘米的有机层中，我们测量了以下参数：水的 pH 值、总酸度、可交换 Ca 和 Mg 的含量、酸溶性和可交换金属（Cu、Pb、Fe、Cd 和 Zn）、有机碳和总氮。同时，我们根据腐殖质形态的欧洲形态功能分类，诊断了有机层的动物活动程度。金属浓度随森林凋落物深度的增加而增加，在有机层和有机-矿物层之间的边界处达到最大值（差异超过一个数量级）。在同一方向上，酸度增加，但交换络合物对 Ca 和 Mg 的饱和度降低。在特定的森林凋落物剖面内，与动物活动最低的层相比，动物活动最高的层中的金属浓度和酸度较低。基于金属、水的 pH 值和交换络合物，在判别分析中，OF 层内土层动物活动程度预测的准确性达到 100%。这些发现表明，在污染停止后，森林凋落物中持续存在的毒性负担的垂直梯度可以解释受污染地区腐殖质形成的恢复模式。
