Abstract This study examined the CO2 system in the estuary of the Oder River, one of the largest rivers entering the Baltic Sea. Three measurable parameters describing the CO2 system, namely total alkalinity (AT), total CO2 (CT), and the partial pressure of CO2 (pCO2), were investigated together with dissolved oxygen, salinity (S), and temperature during two RV Oceania cruises, in May and November of 2016. Large spatial variabilities of AT (1771–2940 μmol kg−1) and CT (1676–2972 μmol kg−1) were determined along the S gradient between the open Baltic Sea and river mouth. In November, the relationships of AT–S and CT-S indicated conservative mixing whereas in May both were strongly affected by biomass production and calcium carbonate formation. The waters of the Oder were oversaturated with CO2 compared to the atmosphere, irrespective of the season, with pCO2 values of 1351 ± 42 μatm in May and 1120 ± 32 μatm in November. In the Szczecin Lagoon, however, pCO2 levels dropped significantly, to 63 μatm, in May, accompanied by an O2 saturation of up to 134% during the same period. The inverse correlation of pCO2 and O2 saturation indicated that the distribution of CO2 and O2 in the estuary at the time of sampling was controlled mostly by biological activity. The very large drop in the pCO2 of the Szczecin Lagoon induced an extreme oversaturation of CaCO3 that triggered mineral calcite precipitation. The mineral precipitation of carbonates in the lagoon may have accounted for as much as 40% of the CT depletion determined in May, with the remaining 60% attributed to the joint effect of net ecosystem production and CO2 air/water gas exchange.

中文翻译：

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奥得河口（波罗的海）CO2系统特征

摘要 本研究调查了奥得河河口的二氧化碳系统，奥得河是进入波罗的海的最大河流之一。描述 CO2 系统的三个可测量参数，即总碱度 (AT)、总 CO2 (CT) 和 CO2 分压 (pCO2)，在两次 RV 大洋洲巡航期间与溶解氧、盐度 (S) 和温度一起进行了研究，在 2016 年 5 月和 11 月。沿着开阔的波罗的海和河口之间的 S 梯度确定了 AT（1771-2940 μmol kg-1）和 CT（1676-2972 μmol kg-1）的大空间变异。11 月，AT-S 和 CT-S 的关系表明混合保守，而 5 月两者都受到生物质产量和碳酸钙形成的强烈影响。与大气相比，奥得河水域的二氧化碳过饱和，无论季节如何，5 月 pCO2 值为 1351 ± 42 μatm，11 月为 1120 ± 32 μatm。然而，在什切青泻湖，5 月份 pCO2 水平显着下降，降至 63 μatm，同时同期氧饱和度高达 134%。pCO2和O2饱和度的反相关表明采样时河口CO2和O2的分布主要受生物活动控制。什切青泻湖 pCO2 的大幅下降导致 CaCO3 极度过饱和，从而引发矿物方解石沉淀。泻湖中碳酸盐的矿物沉淀可能占 5 月确定的 CT 消耗量的 40%，其余 60% 归因于净生态系统生产和 CO2 空气/水气交换的共同作用。