The relative influence of seasonal patterns in hydrological flow and seasonal differences in biological and geochemical activity on stream chemistry patterns is difficult to discern because they covary; temperate systems are characterized by lower mean flow in the summer (i.e. corresponding to deeper flow paths, elevated temperature, and biological activity), and higher mean flow in the winter (i.e. corresponding to shallower flow paths, depressed temperature, and biological dormancy). Using 2018 data, when seasonal stream flow conditions reversed, and two prior conventional water years, the relationship between monthly acid-relevant analyte concentrations and streamflow were compared within and between winter and summer to provide insight into controls on characteristic seasonal chemistry patterns at two mid-Appalachian sites with distinct geology (weatherable mafic and weather resistant siliciclastic). Acid neutralizing capacity (ANC) increased (1) with lower flow, in both seasons and (2) in summer, for all flow conditions. The compounding impacts resulted in a doubling of concentration from typical winter with high flow to summer with low flow at both sites. Base cation patterns tracked ANC at the mafic site, resulting in an ~ 60% increase of from winter with high flow to summer with low flow; distinctions between summer and winter contributed more to the seasonal pattern (72%) than changes in flow. Sulfate increased at the mafic site (1) with higher flow, in both seasons and (2) in winter, for all flow conditions, resulting in an ~ 50% increase from summer with low flow to winter with high flow; distinctions between winter and summer conditions and flow contributed similarly (40–60%) to the typical seasonal chemical pattern. The biogeochemical mechanism driving differences in stream chemistry between summer and winter for the same flow conditions is likely increased rates of natural acidification from elevated soil respiration in summer, resulting in greater bedrock weathering and sulfate adsorption. Findings highlight the significance and consistency of growing vs dormant season variations in temperature and biological activity in driving intra-annual patterns of stream solutes. This data set informs parameterization of hydro-biogeochemical models of stream chemistry in a changing climate at a biologically relevant, seasonal, timescale.

水文流动的季节性模式以及生物和地球化学活动的季节性差异对河流化学模式的相对影响很难辨别，因为它们是协变的;温带系统的特点是夏季平均流量较低（即对应于较深的流路、高温和生物活性），而冬季的平均流量较高（即对应于较浅的流路、低温和生物休眠）。使用 2018 年的数据，当季节性溪流条件逆转时，以及之前的两个常规丰水年，比较了冬季和夏季内以及冬季和夏季之间每月酸相关分析物浓度与溪流之间的关系，以深入了解两个具有不同地质（风化镁铁质和耐风化硅碎屑岩）的阿巴拉契亚中期地点特征季节性化学模式的控制。在所有流动条件下，酸中和能力 （ANC） 增加 （1） 在两个季节和夏季的较低流量 （2）。复合影响导致两个地点的浓度从典型的高流量冬季增加到夏季低流量。碱阳离子模式跟踪镁铁质位点的 ANC，导致从高流量的冬季到低流量的夏季增加了 ~ 60%;夏季和冬季之间的差异对季节性模式的贡献 （72%） 大于流量变化。在所有流动条件下，镁铁质位点的硫酸盐 （1） 在两个季节和 （2） 冬季都以较高的流量增加，导致从夏季低流量到冬季高流量增加 ~ 50%;冬季和夏季条件和流量之间的差异对典型的季节性化学模式的贡献相似 （40-60%）。 在相同的流动条件下，导致夏季和冬季之间河流化学成分差异的生物地球化学机制可能是夏季土壤呼吸增加导致自然酸化速率增加，从而导致基岩风化和硫酸盐吸附加剧。研究结果强调了温度和生物活性的生长季节与休眠季节变化在驱动河流溶质的年内模式中的重要性和一致性。该数据集为在生物相关的季节性时间尺度上不断变化的气候中河流化学的水文生物地球化学模型的参数化提供了信息。