Abstract：
This paper presents the results of the research on the overall distribution of selenium (Se) in various aquatic compartments (water, sediment, plankton and macrophytes) at six selected sites of the Croatian part of the Drava and Danube rivers, the connected floodplain lake and the melioration channel system carried out in two sampling periods (flooding in June and the drought period in September). In addition, the physicochemical water properties, plankton composition and biomass were analysed. Our study revealed low mean Se contents in sediments and water, indicating Se deficiency in the studied freshwater systems. The physicochemical environment, including Se distribution, was primarily influenced by hydrology rather than site-specific biogeochemical and morphological characteristics. The flooding period was characterised by higher Se content in water and higher transparency, nitrate and total nitrogen concentrations than drought conditions. At the river sites, sediment Se content was the highest during the flood period, while at all other sites, higher concentrations were found during the drought, reaching the maximum in the lake. Although Se concentrations were below the threshold for aquatic ecotoxicity, they increased in the following order: water (0.021-0.187 μg Se L-1) < sediments (0.005-0.352 mg Se kg-1) < macrophytes (0.010-0.413 mg Se kg-1) < plankton (0.044-0.518 mg Se kg-1) indicating its possible biomagnification at the bottom of the food chain. Species known for high Se accumulation potential dominated the biomass of the main plankton groups and the composition of the macrophyte community, which may provide a more sensitive and accurate steady-state compartment monitor for Se assessment in freshwater biotopes.
摘要：
本文介绍了硒（Se）在各种水生隔室（水，沉积物,浮游生物和大型植物）在德拉瓦河和多瑙河的克罗地亚部分的六个选定地点，在两个采样期（6月洪水和9月干旱期）中进行了连接的河漫滩湖和改良通道系统。此外,水的物理化学性质，浮游生物组成和生物量进行了分析。我们的研究表明，沉积物和水中的平均硒含量较低，表明所研究的淡水系统中硒缺乏。物理化学环境,包括硒的分布，主要受水文学而不是特定地点的生物地球化学和形态特征影响。洪水时期的特点是水中硒含量较高，透明度较高，硝酸盐和总氮浓度高于干旱条件。在河流遗址，沉积物硒含量在洪水期间最高，而在所有其他网站，在干旱期间发现了更高的浓度，在湖中达到最大。尽管硒浓度低于水生生态毒性的阈值，它们按以下顺序增加：水（0.021-0.187μgSeL-1）<沉积物（0.005-0.352mgSekg-1）<大型植物（0.010-0.413mgSekg-1）<浮游生物（0.044-0.518mgSekg-1）表明其可能在食物链底部进行生物放大。以高硒积累潜力而闻名的物种主导了主要浮游生物群的生物量和大型植物群落的组成，可以为淡水生物群落中的硒评估提供更灵敏，更准确的稳态隔室监测器。
