Collaborative Research: Development of High-Resolution Biomass Burning Records for Tropical South America from Andean Ice Cores

在卫星监测出现之前，南美洲热带地区森林火灾发生的记录很少。 因此，对过去火灾活动、气候变化和人类社会之间关系的基本理解是有限的。 亚马逊森林火灾可以通过在大气、生物圈和土壤之间重新分配大量有机碳来显著影响全球碳循环。 火灾还影响森林健康、生物量丰度和生物多样性。 这一研究项目将利用保存在高海拔安第斯冰原中的分子有机碳特征，提供第一份每年解析的南美洲热带古火灾记录，从而将过去的森林火灾活动及其与气候变化和人类活动的联系联系起来。 将利用奎尔卡亚（秘鲁）冰芯生成跨越过去1 000年的全新世晚期生物量燃烧记录，从而包括中世纪温暖期和小冰期，该冰芯的位置很好，可以接收来自亚马逊盆地和安第斯山脉的有机碳输入，并提供显著的时间限制。 研究人员将使用新开发的分析技术来识别和量化少量冰中的多种痕量有机化合物，提供高分辨率的多分子记录，描述火灾发生和燃烧的材料类型以及新鲜植被的直接排放。 该项目将通过分析安第斯山脉沿着和横跨安第斯山脉的其他几个冰芯中来自植物的有机碳，提供有关高空碳循环动态的信息，这将限制燃烧过程中产生的气溶胶的沉积命运。 将研究通过不完全燃烧实现的有机碳固存，方法是确定与冰芯矿物粉尘和黑碳颗粒有关的高等植物来源的有机碳的特征，并通过放射性碳分析确定其持久性。 在20世纪的火灾记录中观察到的变化是明显的，准周期性的，并不同于奎尔卡亚冰芯氧同位素和灰尘记录，这表明冰芯有机地球化学数据编码独特的气候和人为信号。 通过将这些记录追溯到公元1,000年左右，该项目将提供有关主要气候变化和社会发展中南美热带森林健康的宝贵信息，为确定这一重要资源和有机碳库在未来气候变化中的作用提供基础。该项目将提供有关生物质燃烧变化的宝贵新信息和见解，过去1,000年来，热带植被火灾对碳循环以及火灾发生、气候和人类活动之间的关系产生了影响，在此期间，亚马逊人口增加并随后减少，全球气候发生了显着变化，并发生了工业化。 该项目产生的生物质燃烧信息将有助于推断亚马逊森林健康状况的变化，亚马逊森林是一种重要的自然和经济资源，受到自然和人类相关过程的影响。 亚马逊盆地植被是大气二氧化碳的巨大汇或源。 了解亚马逊流域植被过去的变化如何与全球气候变率相联系，对于确定热带森林在未来气候变化中的作用至关重要。

Records of forest fire occurrence in tropical South America are sparse prior to the advent of satellite monitoring. As a result, basic understanding of the relationships between past fire activity, climate variability, and human societies is limited. Amazonian forest fires can significantly affect the global carbon cycle through redistributing large amounts of organic carbon between the atmosphere, biosphere, and soils. Fires also impact forest health, biomass abundance, and biodiversity. This research project will relate past forest fire activity and its connections to climate variability and human activities by providing the first annually resolved tropical South American paleofire records using molecular organic carbon signatures preserved in high-altitude Andean ice fields. A late Holocene biomass burning record spanning the last 1,000 years, thereby including both the medieval warm period and little ice age, will be generated using the Quelccaya (Peru) ice core, which is well situated to receive organic carbon inputs from the Amazon Basin and Andes and affords remarkable temporal constraints. The investigators will use newly developed analytical techniques to identify and quantify numerous trace-level organic compounds in small volumes of ice, providing high-resolution, multi-molecular records that will describe fire occurrence and the type of material that burned as well as direct emissions from fresh vegetation. The project will provide information about high-altitude carbon cycle dynamics through analysis of vegetation-derived organic carbon in several other ice cores along and straddling the Andean range, which will constrain the depositional fate of aerosols generated during burning. Organic carbon sequestration achieved through incomplete burning will be investigated by characterizing higher plant-derived organic carbon associated with ice core mineral dust and black carbon particles, with its persistence determined through radiocarbon analysis. The variability observed in 20th-century fire records previously developed using this approach is pronounced and quasi-periodic and differs from that of Quelccaya ice core oxygen isotopic and dust records, suggesting that ice core organic geochemical data encodes unique climatic and anthropogenic signals. By extending these records back to roughly 1,000 AD, this project will provide valuable information about tropical South American forest health across major climate shifts and societal developments, providing a basis for determining the role of this important resource and organic carbon pool in future climate change.This project will provide valuable new information and insights regarding biomass burning variability, tropical vegetation fire impacts on the carbon cycle, and the relationships between fire occurrence, climate, and human activity over the last 1,000 years, during which time Amazonian populations expanded and subsequently declined, global climate changed significantly, and industrialization occurred. The biomass burning information generated by this project will help infer changes in the health of Amazonian forests, which are a vital natural and economic resource subject to change from both natural and human-related processes. Amazon Basin vegetation represents a vast sink or source of atmospheric carbon dioxide. Understanding how past changes in Amazon Basin vegetation were connected to global climate variability is important in determining the role of tropical forests in future climate change.