The biogeochemistry of dissolved selenium (Se) was investigated over 3 years (2015–2017) in the subtropical, warm monomictic and meso-eutrophic Lake Kinneret (Sea of Galilee, Israel). We monitored seasonal variation and vertical distribution of dissolved total Se (T.Se), inorganic oxyanions (Se(IV) & Se(VI)), reduced Se fraction (Red.Se), organic (Org.Se) and volatile Se compounds. T.Se varied between ~ 100 and 160 ng L⁻¹ with Red.Se comprising 40–80% of the Se inventory, and Se(VI) dominating over Se(IV) most of the time. The variation in T.Se and species correlated with winter holomixis vs. summer fall stratification periods. The annual cycle includes: (a) increase of T.Se from fall/winter to spring, representing increased allochthonous Se input flux, along with Se recycling via holomixis; (b) decrease of T.Se from spring to the end of the year, representing the diminishing Se inputs and the evolving output fluxes to the lake’s bottom and to the atmosphere. Org.Se variations are directly associated with Chlorophyll-a and primary production attesting for the significant role of phytoplankton activity in the Se cycle. An important Se output flux comprises spring to summer Se uptake by phytoplankton and further volatile compounds production and volatilization accounting for ~ 10% of estimated Se input. The similarity of total dissolved Se concentrations in this work and from mid 1990s attests for long-term stability of the Se inventory. The TVSe concentrations in lacustrine systems being similar to that of estuary systems, the biological role of phytoplankton and eventually the degradation of organic material may produce similar fluxes of volatile Se to the atmosphere.

在亚热带、温暖的单体和中富营养化湖 Kinneret（以色列加利利海）中，对溶解硒 (Se) 的生物地球化学进行了 3 年（2015-2017 年）的调查。我们监测了溶解的总硒 (T.Se)、无机氧阴离子 (Se(IV) 和 Se(VI))、还原硒部分 (Red.Se)、有机 (Org.Se) 和挥发性硒化合物的季节性变化和垂直分布. T.Se 在 ~ 100 和 160 ng L ^-1之间变化Red.Se 占 Se 存量的 40-80%，并且 Se(VI) 在大多数情况下比 Se(IV) 占主导地位。T.Se 和物种的变化与冬季全混合与夏季秋季分层时期相关。年度循环包括：（a）从秋季/冬季到春季 T.Se 的增加，代表外来硒输入通量的增加，以及通过全混合技术的硒回收；(b) 从春季到年底 T.Se 的减少，代表 Se 输入减少和向湖底和大气的输出通量不断变化。Org.Se 变异与叶绿素-a 和初级生产直接相关，证明浮游植物活动在硒循环中的重要作用。一个重要的硒输出通量包括春季到夏季浮游植物对硒的吸收，以及占估计硒输入的约 10% 的进一步挥发性化合物的产生和挥发。这项工作中总溶解硒浓度与 1990 年代中期的相似性证明了硒库存的长期稳定性。湖相系统中的 TVSe 浓度与河口系统中的相似，浮游植物的生物学作用和最终有机物质的降解可能会产生类似的挥发性硒流向大气。