We evaluated long-term trends and seasonal variations in the major physical–chemical properties of the circum-neutral Slapy reservoir (Vltava, Czech Republic) from 1960 to 2019. Mean annual water temperature increased by 2.1 °C, flow maxima shifted by ~ 13 days from the early April to mid-March, and the onset of thermal stratification of water column and spring algal peaks advanced by 19 and 21 days, respectively, due to climate warming. Concentrations of major ions, phosphorus (P), and chlorophyll increased from the 1960s to the 1990–2000s, then decreased due to changing agricultural practices and legislation, intensified wastewater treatment, and decreasing atmospheric pollution. Concentrations of dissolved organic carbon (DOC) decreased from 1960 to the 1990s due to improved wastewater treatment, then began to increase in response to climate change and reduced acidic deposition. Concentrations of water constituents exhibited varying individual long-term and seasonal patterns due to the differing effects of following major processes on their production/removal in the catchment-river system: (1) applications of synthetic fertilizers, liming and farmland draining (NO₃⁻, SO₄²⁻, Cl⁻, Ca²⁺, Mg²⁺, K⁺, and HCO₃⁻), (2) wastewater production and treatment (DOC, P, N forms), (3) road de-icing (Cl⁻ and Na⁺), (4) atmospheric pollution (SO₄²⁻), (5) climate change (DOC), and (6) the aging of reservoirs (NH₄⁺). The water pH increased until the early 1990s, then decreased and exhibited pronounced seasonal variations, integrating the effects of changing external acidity sources and in-lake H⁺ sources and sinks (i.e., microbial CO₂ production/consumption and availability and transformations of inorganic N), and changes in water buffering capacity. Anthropogenic and climatic effects, reservoir aging, and changes in water eutrophication thus may significantly affect water pH also in circum-neutral systems.

我们评估了自1960年至2019年的中性环流Slapy水库（捷克伏尔塔瓦河）的主要物理化学特征的长期趋势和季节性变化。年平均水温提高了2.1°C，流量最大值移动了〜13从4月初到3月中旬的几天，由于气候变暖，水柱和春季藻类峰的热分层分别提前了19天和21天。从1960年代到1990-2000年代，主要离子，磷（P）和叶绿素的浓度增加，然后由于农业实践和法规的变化，废水处理的加强以及大气污染的减少而下降。由于改善了废水处理，从1960年到1990年代，溶解有机碳（DOC）的浓度下降了，然后开始增加以应对气候变化和减少酸性沉积。由于以下主要过程对集水—河流系统中的生产/去除的不同影响，水成分的浓度表现出不同的长期和季节性模式：（1）施用合成肥料，撒石灰和农田排水（否）₃ ^-，SO ₄ ^2-，氯^- ，钙²⁺，镁²⁺，K ⁺，和HCO ₃ ^- ），（2）废水的生产和处理（DOC，P，N形式），（3）道路脱结冰（CL ^-和Na ⁺），（4）大气污染（SO ₄ ^2- ），（5）气候变化（DOC），和贮存器（6）的老化（NH ₄ ⁺）。直到1990年代初，水的pH值一直上升，然后下降，并表现出明显的季节性变化，综合了外部酸度源和湖中H ⁺源和汇（例如微生物CO _{2）变化的影响。}生产/消费以及无机N的可获得性和转化，以及水缓冲能力的变化。人为和气候影响，水库老化以及水富营养化的变化也可能在环中性系统中显着影响水的pH值。