Abstract Reservoirs hold a detailed record of the changes in the input of sediments and nutrients over decades to centuries. Paleolimnological multi-proxy analysis makes it possible to reconstruct baseline conditions to infer early evidence of environmental change. Our study aims to reconstruct historical human impacts derived from urban development on the San Roque reservoir (Cordoba, Argentina) related to the centennial dynamics of sedimentary and eutrophication processes. A paleolimnological record, dated by 210Pb and 137Cs, made it possible to identify two stages during the environmental evolution of the San Roque reservoir. Physical processes, such as fluvial discharge and water level variation, dominantly ruled stage 1 (Unit C) during the initial infilling of the reservoir. Nutrient load and eutrophication processes controlled stage 2 (Units B and A). Stage 1 (77-55 cm; AD 1921 to 1965) occurred before and after the second dam was built and while the level of water increased by ≈ + 8 m; it displayed a high variation in mean grain size and maximum values of magnetic susceptibility. Stage 2 (AD 1965–2017) records a new reservoir base level and the maintenance of high water levels and comparatively more stable conditions. Regarding the eutrophication process throughout stage 2, three sub-stages were defined: a) Sub-stage I (AD 1965–1985) is a period of incipient eutrophication; b) Sub-stage II (AD 1985–2005) is an interval of increase of eutrophication as shown by the increase in several organic proxies related to the abundance of phytoplankton. Echinenone, zeaxanthin and myxoxanthophyll indicate that cyanobacteria increased concentration by three-to four-fold in comparison with the previous sub-stage. c) Sub-stage III (AD 2005–2017) shows the transition to a hypereutrophic state. Diatomea (fuco and diato), dinophyceae (diadino), chlorophyta (lut) and cryptophyta (allo) groups show a comparatively higher contribution. Our results mostly highlight that during the last century the main drivers of changes in the environmental state of the San Roque reservoir were trophic, fluvial and hydrometeorological. These results might provide tools for anticipating future scenarios for water management plans under increasing anthropic pressure.

中文翻译：

---

南美亚热带水库百年富营养化过程的古湖泊学重建

摘要 水库详细记录了几十年来沉积物和养分输入的变化。古湖泊学多代理分析使重建基线条件以推断环境变化的早期证据成为可能。我们的研究旨在重建城市发展对圣罗克水库（阿根廷科尔多瓦）与沉积和富营养化过程的百年动态相关的历史人类影响。一份年代为 210Pb 和 137Cs 的古湖泊学记录使得确定圣罗克水库环境演变过程中的两个阶段成为可能。在水库初始充填过程中，河流流量和水位变化等物理过程占主导地位。营养负荷和富营养化过程控制第 2 阶段（单元 B 和 A）。第 1 阶段（77-55 厘米；公元 1921 年至 1965 年）发生在第二座大坝建成前后，而水位增加了 ≈ + 8 m；它在平均晶粒尺寸和磁化率最大值方面表现出很大的变化。第 2 阶段（公元 1965-2017 年）记录了一个新的水库基础水位以及维持高水位和相对更稳定的条件。关于整个阶段 2 的富营养化过程，定义了三个子阶段： a) 子阶段 I（公元 1965-1985 年）是初期富营养化时期；b) 子阶段 II（公元 1985-2005 年）是富营养化增加的间隔，如与浮游植物丰度相关的几种有机代理的增加所示。海胆酮，玉米黄质和粘黄素表明，与之前的亚阶段相比，蓝藻的浓度增加了三到四倍。c) 子阶段 III（公元 2005-2017 年）显示了向富营养化状态的过渡。硅藻（fuco 和 diato）、甲藻（diadino）、绿藻（lut）和隐藻（allo）组显示出相对较高的贡献。我们的结果主要强调，在上个世纪，圣罗克水库环境状态变化的主要驱动因素是营养、河流和水文气象。这些结果可能为在不断增加的人为压力下预测水资源管理计划的未来情景提供工具。硅藻（fuco 和 diato）、甲藻（diadino）、绿藻（lut）和隐藻（allo）组显示出相对较高的贡献。我们的结果主要强调，在上个世纪，圣罗克水库环境状态变化的主要驱动因素是营养、河流和水文气象。这些结果可能为在不断增加的人为压力下预测水资源管理计划的未来情景提供工具。硅藻（fuco 和 diato）、甲藻（diadino）、绿藻（lut）和隐藻（allo）组显示出相对较高的贡献。我们的结果主要强调，在上个世纪，圣罗克水库环境状态变化的主要驱动因素是营养、河流和水文气象。这些结果可能为在不断增加的人为压力下预测水资源管理计划的未来情景提供工具。