作者：Boussagol, P., Vennin, E., Motreuil, S., Bonnotte, A., Jouve, G., Millet, L., Munier, T. & Visscher, P.

From spring 2022 to late summer 2024, a study of Lake Ilay's water column and sediment cores analyzed key environmental parameters. Conductivity, temperature, and chlorophyll-a were measured at 2 m, while pH, conductivity, temperature, calcium (Ca2+), and alkalinity were monitored within the top 20 m. The lake exhibited significant seasonal variations, remaining thermally and chemically stratified for at least 8 months yearly. Six sediment cores (1-23 m depth) were analyzed for mineralogy, dry bulk density, and organic/inorganic carbon, complemented by cryo-scanning electron microscopy observations. This multi-analytical approach provided insights into micrite precipitation, the primary component of lacustrine carbonate muds. Building on these findings, an integrated model for carbonate production in stratified lakes was developed. It incorporates ionic circulation between the water column and sediment, offering a novel framework for micrite formation. This approach carries broad implications for lacustrine and marine systems over geological timescales, shedding light on carbonate precipitation processes, ion dynamics, and their availability across the fluid envelope and the sedimentary reservoir. A key finding is that carbonate production in the water column is brief in time, with preservation and accumulation restricted to shoreline platforms, submerged under shallow water, that form a belt around the lake. However, lacustrine micrite formation continues in sediments at all depths, linked to exopolymer degradation. The carbonate platforms result from vertical accretion, and their lateral extent is defined by the lower boundary of carbonate dissolution along the topographic slope.

2022年春至2024年夏末，一项研究对伊莱湖的水柱和沉积物岩心进行了分析。在水深2 m处测量了电导率、温度和叶绿素a，并在上层20 m内监测了pH、电导率、温度、钙离子和碱度。该湖每年至少有8 个月处于热力与化学分层状态，季节性变化显著。研究人员分析了6根沉积物岩心（水深1–23 m）的矿物组成、干容重及有机/无机碳，并辅以冷冻扫描电镜观察。这种多手段联用方法揭示出湖相碳酸盐软泥的主要成分——泥晶的形成机制。在此基础上，研究提出了一个适用于分层湖泊的碳酸盐生产综合模型。该模型整合了水柱与沉积物之间的离子循环，为泥晶形成提供了一个新框架。这一思路对地质时间尺度上的湖泊与海洋系统具有广泛意义，有助于理解碳酸盐沉淀过程、离子动力学及其在流体包络层和沉积储库中的可用性。一项关键发现是：水柱中的碳酸盐生产在时间上很短暂，其保存与堆积仅限于环绕湖泊的浅水岸线台地。然而，与胞外聚合物降解相关的泥晶形成过程在所有深度的沉积物中仍在持续。碳酸盐台地由垂向加积形成，其侧向范围受地形斜坡上碳酸盐溶解下边界的控制。

（来源：Limnology and Oceanography 2026 Issue 2  DOI: 10.1002/lno.70334）