Quantitative evaluation of human and climate forcing on erosion in the alpine Critical Zone over the last 2000 years
Quantitative evaluation of human and climate forcing on erosion in the alpine Critical Zone over the last 2000 years
复制标题
DOI：
10.1016/j.quascirev.2021.107127
复制
发表时间：
2021-09
影响因子：
4
通讯作者：
W. Rapuc;J. Bouchez;P. Sabatier;Kim Genuite;J. Poulenard;J. Gaillardet;F. Arnaud
中科院分区：
文献类型：
--
作者：
W. Rapuc;J. Bouchez;P. Sabatier;Kim Genuite;J. Poulenard;J. Gaillardet;F. Arnaud
土壤侵蚀是影响临界区（CZ）的主要环境威胁之一，从而影响生态系统服务和人类社会。随着时间的推移，物理侵蚀与气候变化和长期人类压力下的景观演变有关。在侵蚀最严重的山区，结合大的空间和时间的方法可以评估这些强迫因素对侵蚀速率的影响。在这里，我们采用了一种基于湖泊沉积物的回顾性方法来重建高山景观侵蚀的长期演变。意大利阿尔卑斯山的伊塞奥湖是一个大流域（1777平方公里）所有侵蚀产物的天然汇。这个集水区是意大利南部阿尔卑斯山的代表，那里的全新世人类活动和气候波动是众所周知的。该方法结合了源-汇方法，使用同位素地球化学（ε Nd，87 Sr/86 Sr）与覆盖过去2000年的湖泊沉积物剖面的多代理研究。所应用的方法使我们能够解开气候和土地利用的作用，通过其差异的影响，目前在集水区的各种岩石类型的侵蚀迫使因素。事实上，伊塞奥流域的高海拔部分，冰川的前进和后退驱动了侵蚀，呈现出与位于流域下部的沉积岩不同的同位素特征，人类活动和降水都影响了侵蚀。制作了一份过去2000年冰川侵蚀的编年史。一旦气候趋势被强调，沉积岩侵蚀的信号被调查，以了解人类的影响。从罗马时期到工业时代，有记录表明，有几个时期的森林砍伐和人类压力的增加。根据沉积岩推断的过去的产沙量显示出最高值（> 80 t km − 2）。yr-1）在人类活动密集的时期。因此，自罗马时代晚期以来，人类活动似乎是北方意大利山地环境物理侵蚀的主导因素。本研究首次提出了通过时间重建来自湖泊沉积物的产沙量与沉积物源识别和定量评价的CZ侵蚀驱动程序。
Soil erosion is one of the main environmental threats affecting the Critical Zone (CZ) and thus ecosystem services and human societies. Through time, physical erosion is linked to both climate variations and the landscape evolution under long-term human pressures. In mountainous areas where erosion is highest a combination of large spatial and temporal approaches allows to assess the effect of these forcing factors on erosion rates. Here, we apply a retrospective approach based on lake sediments to reconstruct the long-term evolution of erosion in alpine landscapes. Lake Iseo in the Italian Alps acts as a natural sink for all the erosion products from a large catchment (1777 km2). This catchment is representative of the southern Italian Alps, where Holocene human activity and climate fluctuations are well known. The approach combines a source-to-sink method, using isotopic geochemistry (εNd,87Sr/86Sr) associated to a multiproxy study of a lacustrine sediment section covering the last 2000 years. The applied method allows us to disentangle the role of climate and land use as erosion forcing factors through their differential impact on the various rock types present in the catchment. Indeed, the high-altitude part of the Iseo catchment, where glacier advances and retreats drive the erosion, presents isotopic signature different from those of the sedimentary rocks located in the lower part of the catchment, where both human activities and precipitations impacted erosion through time. A chronicle of glacial erosion over the last 2000 years was produced. Once the climatic trend was highlighted, the signal of erosion of sedimentary rocks was investigated to understand the influence of humans. From the Roman Period to the Industrial Age several periods of deforestation and increased human pressure were documented. The past sediment yield inferred for sedimentary rocks exhibits the highest values (>80 t km−2. yr−1) at periods of intense human practices. Hence, since the late Roman Period, human activities seem to be the dominant forcing factor of the physical erosion in mountainous environment of northern Italy. This study presents the first reconstruction through time of sediment yield derived from lake sediments associated with sediment sources identification and quantitative evaluation of the CZ erosion drivers.