We performed geochemical analyses of two lake sediment cores (1.25 and 1.5 m long) from Lago Rogaguado, which is a large (315 km2) and shallow lake in the Llanos de Moxos, Bolivian Amazon, to investigate Holocene environmental changes based on a multi-proxy dataset (XRF, density, grain size, C:N, and macrocharcoal). One of the two cores provides a history of environmental changes in the Llanos de Moxos from 8100 cal BP until present, which supplements previously published pollen and microscopic charcoal records. Our analyses indicate lake expansion at 5800 cal BP, which may relate to tectonic activity. This was followed by further increasing lake levels, peaking at approximately 1050–400 cal BP, which supports increasingly wetter conditions in the Llanos de Moxos after the mid-Holocene. A fourfold increase in macroscopic charcoal accumulation rate and a more than fivefold increase in sedimentation rates supports anthropogenic fire activity at around 1450 cal BP (500 CE), suggesting that pre-Columbian populations used fire to actively manage the landscape during a period of maximum lake levels around Lago Rogaguado. From 400–100 cal BP, higher C:N, larger grain sizes and peaks in macroscopic charcoal accumulation rates suggest increased watershed erosion associated with increased biomass burning, possibly related to intensified land use.

中文翻译：

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重建玻利维亚亚马逊拉戈罗加瓜多的全新世景观和环境变化

我们对来自 Lago Rogaguado 的两个湖泊沉积物岩心（1.25 米和 1.5 m 长）进行了地球化学分析，该湖是玻利维亚亚马逊 Llanos de Moxos 的一个大型浅湖（315 平方公里），以基于多维度研究全新世环境变化。代理数据集（XRF、密度、粒度、C:N 和宏碳）。两个核心之一提供了 Llanos de Moxos 从 8100 cal BP 到现在的环境变化历史，补充了之前发表的花粉和微观木炭记录。我们的分析表明，在 5800 cal BP 时湖泊扩张，这可能与构造活动有关。随后湖泊水位进一步升高，峰值约为 1050-400 cal BP，这支持了全新世中期之后 Llanos de Moxos 越来越潮湿的条件。宏观木炭积累率的四倍增加和沉积率的五倍以上增加支持大约 1450 cal BP (500 CE) 的人为火灾活动，这表明前哥伦布时期的人口在最大湖泊期间使用火来积极管理景观Lago Rogaguado 附近的水平。从 400-100 cal BP，更高的 C:N、更大的颗粒尺寸和宏观木炭积累率的峰值表明与生物量燃烧增加相关的流域侵蚀增加，可能与土地利用集约化有关。