Anthropogenic eutrophication and spreading anoxia in freshwater systems is a global concern. Little is known about anoxia in earlier historic times under weaker human impact, or under prehistoric natural conditions with different trophic, land cover and climatic regimes. We use a novel approach that combines high‐resolution hyperspectral imaging with µ‐XRF and HPLC‐pigment data, which allows us to assess chloropigments (productivity) and bacteriopigments (anoxia) at seasonal subvarve‐scale resolution. Our ~9700 cal a bp varved sediment record from NE Poland suggests that productivity increased stepwise from oligotrophic Early Holocene conditions (until ~9200 cal a bp) to mesotrophic conditions in the Mid‐ and Late Holocene. Natural eutrophication was mainly a function of progressing landscape evolution with intense weathering under dense forest and warm‐moist climatic conditions. Generally, anoxia increased with increasing productivity. Seasonal anoxia and some multi‐decadal periods of meromixis were the common mixing patterns throughout the Holocene except for a period of persisting meromixis between ~5200 and 2000 cal a bp. Anthropogenic deforestation around 400 cal a bp resulted in substantially better lake oxygenation despite high productivity. In this small lake, aquatic productivity and lakeshore forest cover (wind shield) were more important factors controlling oxic/anoxic conditions than Holocene temperature variability.

中文翻译：

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来自波兰东北部Łazduny湖脉状沉积物的全新世高分辨率水生生产力，季节性缺氧和混合生殖的记录：一种新颖的多代理方法的见解

淡水系统中的人为富营养化和缺氧扩散是全球关注的问题。在较弱的人类影响下，或在史前自然条件下，营养，土地覆盖和气候状况不同的情况下，人们对早期的缺氧知之甚少。我们使用一种新颖的方法，将高分辨率的高光谱成像与µXRF和HPLC色素数据相结合，这使我们能够在季节性子瓣规模分辨率下评估氯色素（生产力）和细菌色素（缺氧）。我们来自波兰东北部的〜9700 cal a bp脉状沉积记录表明，从贫营养的全新世早期开始，生产力逐步提高（直到〜9200 cal a bp））到全新世中期和后期的中营养条件。自然富营养化主要是在茂密的森林和温暖湿润的气候条件下，随着强烈的风化而不断发展的景观的一种功能。通常，缺氧随着生产率的提高而增加。在整个全新世，季节性缺氧和部分混合纪数是数十年的普遍混合模式，除了持续存在的混合纪元介于约5200和2000 cal abp之间。尽管生产率高，但人为砍伐约400 cal bp仍导致湖泊氧合作用明显改善。在这个小湖中，与全新世温度变化相比，水生生产力和湖岸森林覆盖率（挡风玻璃）是控制有氧/缺氧条件的重要因素。