Data for: Accumulation of metals and changes in the composition of freshwater lake organic sediments during the Holocene

Distribution of metals in freshwater sediment strata formed during the Holocene in the territory of Latvia has been studied rather insufficiently. Considering the large volume of accumulated organic matter in sediments, studies of the content of metal elements in sediments can help to determine the peculiarities of metal accumulation process in limnic systems and biogeochemical cycling of metals. Lake Pilvelis, located in the eastern part of Latvia (the northern part of Europe), was selected as the study site. Lake Pilvelis is a small lake of a glacial origin, and more than 90% of its depression is filled with organic-rich sediments, such as gyttja or freshwater sapropel, with an average thickness of 450 cm. Development stages of Lake Pilvelis since circa 10 000 cal BP are described in detail by means of reconstruction of the Holocene palaeoenvironmental conditions in the lake using multiproxy sedimentary records. This study represents analysis of the elemental composition and content of metallic elements in gyttja with the main target to characterise the accumulation rate of metals in a full profile of gyttja and to determine the anthropogenic impact depending on the evolution of the lake and genesis of sediment organic matter. Correlation among the components characterising such sediments as gyttja and metallic elements showed element distribution into three main groups according to the content of organic or mineral compounds. The principal component analysis revealed four main impact factors indicating the origin of metallic elements and the accumulation tendencies of metals in sediment layers.

针对拉脱维亚境内全新世（Holocene）形成的淡水沉积地层中的金属元素分布的相关研究仍较为匮乏。鉴于沉积物中累积了大量有机质，对沉积物中金属元素含量的研究有助于阐明湖沼系统（limnic systems）中金属元素的富集过程特征以及金属的生物地球化学循环规律。本研究选取位于拉脱维亚东部（欧洲北部地区）的皮尔韦利斯湖（Lake Pilvelis）作为研究区域。该湖为冰川成因小型湖泊，其湖盆90%以上被富有机质沉积物填充，主要为腐泥（gyttja）或淡水腐泥（freshwater sapropel），平均厚度达450厘米。已有研究借助多代用沉积记录重建该湖的全新世古环境条件，详细阐述了皮尔韦利斯湖自约10000校准年前（cal BP）以来的演化阶段。本研究针对腐泥样品的元素组成及金属元素含量开展分析，核心目标为刻画腐泥完整剖面中的金属元素富集速率，并结合湖泊演化与沉积物有机质成因，明确人类活动的影响程度。对腐泥类沉积物特征组分与金属元素的相关性分析表明，依据有机质或矿物化合物的含量，金属元素可划分为三大分布群组。主成分分析（Principal Component Analysis）结果识别出四大主要影响因子，可用于阐释金属元素的来源及其在沉积层中的富集趋势。