Environmental Geosciences, University of Basel, Bernoullistrasse 30, CH-4056 Basel, Switzerland.
Dipartimento di AGRARIA, Università degli Studi Mediterranea di Reggio Calabria, Italy.
Environ Res. 2018 Jan;160:195-202. doi: 10.1016/j.envres.2017.09.020. Epub 2017 Oct 6.
The expected growing population and challenges associated with globalisation will increase local food and feed demands and enhance the pressure on local and regional upland soil resources. In light of these potential future developments it is necessary to define sustainable land use and tolerable soil loss rates with methods applicable and adapted to mountainous areas. Fallout-radionuclides (FRNs) are proven techniques to increase our knowledge about the status and resilience of agro-ecosystems. However, the use of the Caesium-137 (Cs) method is complicated in the European Alps due to its heterogeneous input and the timing of the Chernobyl fallout, which occurred during a few single rain events on partly snow covered ground. Other radioisotopic techniques have been proposed to overcome these limitations. The objective of this study is to evaluate the suitability of excess Lead-210 (Pb) and Plutonium-239+240 (Pu) as soil erosion tracers for three different grassland management types at the steep slopes (slope angles between 35 and 38°) located in the Central Swiss Alps. All three FRNs identified pastures as having the highest mean (± standard deviation) net soil loss of -6.7 ± 1.1, -9.8 ± 6.8 and -7.0 ± 5.2 Mg ha yr for Cs, Pb and Pu, respectively. A mean soil loss of -5.7 ± 1.5, -5.2 ± 1.5 and-5.6 ± 2.1 was assessed for hayfields and the lowest rates were established for pastures with dwarf-shrubs (-5.2 ± 2.5, -4.5 ± 2.5 and -3.3 ± 2.4 Mg ha yr for Cs, Pb and Pu, respectively). These rates, evaluated at sites with an elevated soil erosion risk exceed the respective soil production rates. Among the three FRN methods used, Pu appears as the most promising tracer in terms of measurement uncertainty and reduced small scale variability (CV of 13%). Despite a higher level of uncertainty, Pb produced comparable results, with a wide range of erosion rates sensitive to changes in grassland management. Pb can then be as well considered as a suitable soil tracer to investigate alpine agroecosystems.
预计人口增长和全球化带来的挑战将增加当地粮食和饲料需求，并对当地和区域旱地土壤资源造成更大压力。鉴于这些潜在的未来发展，有必要采用适用于山区的方法来定义可持续土地利用和可容忍的土壤流失率。沉降放射性核素（FRN）是一种已被证实的技术，可以帮助我们更好地了解农业生态系统的现状和恢复能力。然而，由于切尔诺贝利沉降物在欧洲阿尔卑斯山输入的不均匀性以及发生时间（发生在部分积雪覆盖的地面上的几次单一降雨事件中），铯-137（Cs）方法的使用较为复杂。已经提出了其他放射性同位素技术来克服这些限制。本研究的目的是评估过量铅-210（Pb）和钚-239+240（Pu）作为三种不同草地管理类型在瑞士中部阿尔卑斯山陡峭斜坡（坡度在 35 到 38°之间）的土壤侵蚀示踪剂的适用性。所有三种 FRN 都确定了牧场的平均（±标准偏差）净土壤损失最高，分别为-6.7±1.1、-9.8±6.8 和-7.0±5.2 Mg ha yr。对于干草田，评估的平均土壤损失为-5.7±1.5、-5.2±1.5 和-5.6±2.1，而矮灌木牧场的土壤流失率最低（对于 Cs、Pb 和 Pu，分别为-5.2±2.5、-4.5±2.5 和-3.3±2.4 Mg ha yr）。在具有较高土壤侵蚀风险的地点评估的这些速率超过了各自的土壤生产力。在使用的三种 FRN 方法中，Pu 似乎是最有前途的示踪剂，因为它的测量不确定性和较小尺度可变性较低（CV 为 13%）。尽管存在较高的不确定性，但 Pb 产生了可比的结果，其侵蚀率范围广泛，对草地管理的变化敏感。因此，Pb 也可以被视为研究高山农业生态系统的合适土壤示踪剂。
