Total alkalinity (TA) is one of the four main carbonate system variables and is a conventionally measured parameter used to characterise marine water carbonate chemistry. It is an important indicator of a waterbody's buffering capacity and a measure of its ability to resist acidification, a matter of growing concern in the marine environment. Although TA is primarily associated with the inorganic components of seawater such as bicarbonate, there is a growing consensus that dissolved organic matter (DOM) can significantly contribute to TA in coastal waters. This organic fraction of TA (OrgAlk) is typically deemed negligible and is not accounted for in conventional TA expressions. However, omission of OrgAlk can lead to the propagation of errors in subsequent carbonate system calculations and to misinterpretation of key carbonate chemistry descriptors such as calcium carbonate saturation states. Here we provide an overview of OrgAlk contributions to TA and investigate the implications of its omission in carbonate system studies conducted in coastal waters. We examine the prevalence of OrgAlk across both coastal and pelagic waters using publicly available carbonate system data products, such as GLODAP and GOMECC. Current measures to account for, incorporate and characterise the contribution of OrgAlk to TA are also critically examined.

总碱度 (TA) 是四个主要碳酸盐系统变量之一，是用于表征海水碳酸盐化学的常规测量参数。它是水体缓冲能力的重要指标，也是衡量其抗酸化能力的重要指标，这是海洋环境中日益受到关注的问题。尽管 TA 主要与海水的无机成分（如碳酸氢盐）有关，但越来越多的人认为溶解有机物 (DOM) 对沿海水域的 TA 有显着贡献。TA (OrgAlk) 的这种有机部分通常被认为可以忽略不计，在传统的 TA 表达式中没有考虑在内。然而，遗漏 OrgAlk 会导致后续碳酸盐系统计算中的错误传播，并导致对关键碳酸盐化学描述符（如碳酸钙饱和状态）的误解。在这里，我们概述了 OrgAlk 对 TA 的贡献，并调查了在沿海水域进行的碳酸盐系统研究中遗漏它的影响。我们使用公开可用的碳酸盐系统数据产品（例如 GLODAP 和 GOMECC）检查了 OrgAlk 在沿海和远洋水域的流行情况。还严格审查了当前用于解释、合并和表征 OrgAlk 对 TA 贡献的措施。在这里，我们概述了 OrgAlk 对 TA 的贡献，并调查了在沿海水域进行的碳酸盐系统研究中遗漏它的影响。我们使用公开可用的碳酸盐系统数据产品（例如 GLODAP 和 GOMECC）检查了 OrgAlk 在沿海和远洋水域的流行情况。还严格审查了当前用于解释、合并和表征 OrgAlk 对 TA 贡献的措施。在这里，我们概述了 OrgAlk 对 TA 的贡献，并调查了在沿海水域进行的碳酸盐系统研究中遗漏它的影响。我们使用公开可用的碳酸盐系统数据产品（例如 GLODAP 和 GOMECC）检查了 OrgAlk 在沿海和远洋水域的流行情况。还严格审查了当前用于解释、合并和表征 OrgAlk 对 TA 贡献的措施。