Purpose

The aim of this study was to estimate the impact of lake disappearance, groundwater table fluctuations, and some aspects of human pressure on stages of soil cover development in the catchment of Lake Rakutowskie.

Materials and methods

Research was conducted in soil chronosequence composed of eight soil profiles located in 785-m-long transect. Soils were sampled every 10 cm. Physical and chemical properties were determined with the use of disturbed and undisturbed samples. Radiocarbon dates were obtained for the bottom part of peat in each soil profile. The mineral composition of selected soil samples was determined using the X-ray diffraction (XRD) method. Additionally, the hydrological conditions were continuously monitored from July 27, 2013 to September 23, 2014.

Results and discussion

An increased rate of shallow lakes overgrowth and final disappearance is a commonly observed process in the European lowlands. This paper presents and discusses the influence of changes in the range of the Lake Rakutowskie wetlands complex (central Poland) and water level fluctuations on soil cover transformation in the immediate vicinity of the lake. Five major phases of soil cover development (from Subaquatic Histosols (Limnic) to Hypereutric Regosol (Drainic, Humic)) were hypothetically reconstructed based on detailed studies of soil physical and chemical properties, mineral composition, water level fluctuations, and radiocarbon dating. The degree of peat decomposition in the studied profiles increased with the distance from the contemporary lake surface. Along with the progressive dehydration and mineralization of organic soils, their physical and chemical properties deteriorated, which is visible, e.g., in soil structure, and mineral and chemical composition (especially TOC and TN). Obtained radiocarbon ages of selected samples indicate that the oldest peat layers developed about 5856 cal BCE (6970 ± 70 ¹⁴C BP), while the youngest were deposited about 1074 cal CE (980 ± 40 ¹⁴C BP)–1573 cal CE (300 ± 35 ¹⁴C BP). Hydrological studies indicate a progressive process of lake disappearance.

Conclusions

The process of soil cover transforming of the studied area takes place relatively quick, mainly recently due to the influence of human activity. Based on these results, it can be predicted that the lake will most likely disappear in a relatively short time, and the soil cover will be entirely in the fifth phase (P5) of evolution.

中文翻译：

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消失的湖沿岸土壤发展阶段-以波兰中部为例

目的

这项研究的目的是评估湖泊消失，地下水位波动以及人类压力对拉库托夫斯基湖流域土壤覆盖发展阶段的影响。

材料和方法

在由785米长的样条线中的八个土壤剖面组成的土壤时间序列中进行了研究。每10厘米取样一次土壤。物理和化学性质是通过使用受干扰和不受干扰的样品确定的。获得了每种土壤剖面中泥炭底部的放射性碳数据。使用X射线衍射（XRD）方法确定选定土壤样品的矿物成分。此外，自2013年7月27日至2014年9月23日，对水文状况进行了连续监测。

结果与讨论

在欧洲低地，通常观察到浅湖过度生长和最终消失的速度增加。本文介绍并讨论了Rakutowskie湖湿地综合体（波兰中部）范围变化和水位波动对紧邻湖面土壤覆盖变化的影响。根据对土壤理化性质，矿物质组成，水位波动和放射性碳定年的详细研究，假设重建了土壤覆盖发展的五个主要阶段（从亚水生组织溶胶（Limnic）到超富集性雷哥溶胶（Drainic，Humic））。研究剖面中的泥炭分解程度随距当代湖面的距离而增加。随着有机土壤的逐步脱水和矿化，它们的物理和化学特性变差了，例如在土壤结构，矿物和化学组成（尤其是TOC和TN）中可见。选定样品的放射性碳年龄表明，最老的泥炭层形成了约5856 cal BCE（6970±70）¹⁴ C BP），而最小的沉积物大约为1074 cal CE（980±40 ¹⁴ C BP）–1573 cal CE（300±35 ¹⁴ C BP）。水文研究表明湖泊逐渐消失。

结论

研究区域的土壤覆盖变化过程发生得相对较快，这主要是由于人类活动的影响。根据这些结果，可以预测湖泊将在相对较短的时间内消失，土壤覆盖将完全处于进化的第五阶段（P5）。