Borates are the third most important component of total alkalinity (A_T) in the oxic waters. Their concentrations are a function of the dissociation constant of boric acid and total boron (TB) concentration. The latter is approximated from salinity (S) as boron behave conservatively in the seawater. The linear dependencies between TB and S developed for the open ocean contain no intercept suggesting that river water contains no boron. Based on the historical data and our own measurements we identified a TB vs. S relationship specific for the Baltic Sea: TB [μmol kg⁻¹] = 10.838 ∗ S + 13.821. In the series of the sensitivity tests we analysed what effect can have this anomaly on the determination of borate alkalinity (A_B) and on the calculations within the CO₂ system performed with A_T as an input variable. Due to the high pK_a for boric acid the influence of TB anomaly on A_B exists only for pH > 8. The highest deviation in A_B appears at low salinities. When salinity increases the effect becomes smaller and at salinities > 14, due to lower slope in TB vs. S dependency in the Baltic than in the open ocean, the effect on A_B turns to negative and decreases further with the S increase. These uncertainties in A_B influence calculations of pCO₂ (CO₂ partial pressure) and pH, when C_T (total CO₂ concentration) and A_T are used as input parameters (the combination used in biogeochemical models). For pCO₂ the discrepancies in calculations are not very much dependent on the A_T. The highest are observed for low salinities and pH of 8.2–8.4, however they do not exceed 10 μatm. This relatively low influence of TB anomaly on pCO₂ calculations is a result of the high distance on the pH scale between high pCO₂ conditions (low pH) and the highest A_B anomaly (high pH). In case of pH calculations the highest influence of TB anomaly is observed for the low A_T and low S waters. For three different A_T considered in our study the highest pH errors (up to 0.05 pH unit) were observed for A_T = 500 μmol kg⁻¹, while the lowest (up to 0.01 pH unit) were observed for highly buffered waters (A_T = 3000 μmol kg⁻¹). Irrespective of the A_T the highest errors were found for low C_T simulating low pCO₂ (and thus high pH) conditions. This is due to the high pK_a for boric acid that shifts the effects of the TB anomaly to high pH values. Although the observed discrepancies in pH and pCO₂ calculations due to TB anomaly manifest themselves only at the specific environmental conditions the use of experimentally obtained TB vs. S dependency will increase the accuracy of the CO₂ system calculations for the Baltic Sea and likely for other brackish systems.

硼酸盐是含氧水中总碱度（A _T）的第三重要成分。它们的浓度是硼酸解离常数和总硼（TB）浓度的函数。后者是从盐度（S）近似得出的，因为硼在海水中表现保守。为远洋开发的TB和S之间的线性相关性没有截距，表明河水不含硼。根据历史数据和我们自己的测量，我们确定了特定于波罗的海的TB与S的关系：TB [ μmolkg ^-1 ] = 10.838 * S + 13.821。在一系列敏感性测试中，我们分析了这种异常对硼酸碱度（A _B）的确定以及CO内计算的影响。₂系统以A _T作为输入变量执行。由于硼酸的pK _a高，仅在pH> 8时，TB异常对A _B的影响才存在。在低盐度下，A _B的最大偏差出现。当盐度增加时，由于波罗的海的TB与S依赖关系的坡度比公海低，在盐度大于14时，影响变得更小，对A _B的影响变为负，并随着S的增加而进一步减小。当C _T（总CO ₂浓度）和A _T时，_AB中的这些不确定性会影响pCO ₂（CO ₂分压）和pH的计算用作输入参数（在生物地球化学模型中使用的组合）。对于的pCO ₂中计算的差异不在一个非常依赖_牛逼。在低盐度和pH值为8.2-8.4时观察到最高，但是不超过10μatm。TB异常对pCO ₂计算的相对较低的影响是高pCO ₂条件（低pH）和最高A _B异常（高pH）之间的pH值范围相距遥远的结果。在进行pH计算的情况下，对于低A _T和低S水，TB异常的影响最大。对于三个不同的A _T在我们的研究中考虑到，对于A _T  = 500μmolkg ^-1，观察到最高的pH误差（高达0.05 pH单位），而对于高度缓冲的水（A _T  = 3000μmolkg ），观察到了最低的pH误差（高达0.01 pH单位）。^-1）。不管A _T为何，在模拟低pCO ₂（因此pH高）条件下的低C _T条件下，发现的误差最高。这是由于硼酸的高pK _a将TB异常的影响转移到了高pH值。尽管观察到pH和pCO _2的差异由于TB异常导致的计算仅在特定的环境条件下才会体现出来，使用实验获得的TB与S的依赖关系将提高波罗的海以及其他咸淡系统的CO ₂系统计算的准确性。