The abundance and distribution of barium (Ba) serve as a reliable proxy for oceanic biogeochemical processes. Its cycling in the coastal regions, however, is complicatedly regulated by multiple sources/sinks. In this study, the spatial distribution of dissolved barium concentrations in a large coastal lagoon (Chilika lagoon, India) and its source waters have been investigated for three different seasons (pre-monsoon (May 2017), monsoon (August 2017), and post-monsoon (January 2018)). Additionally, contents of Ba and other elements in the bed and suspended sediments in their different fractions (bulk, clay, and exchangeable) have also been investigated. These data were used to constrain coastal processes in regulating coastal Ba inventory. The dissolved [Ba] of the Bay of Bengal (median ~ 37 nmol/kg (range: 30–53 nmol/kg)) are lower than that observed for the river (median ~ 319 nmol/kg (range: 256–583 nmol/kg)), and groundwater (median ~ 464 nmol/kg (range: 20–4428 nmol/kg)) samples. The salinity-weighted barium concentrations of the Chilika lagoon for the pre-monsoon (1052 nmol/kg) and monsoon (652 nmol/kg) seasons are higher compared to that during the post-monsoon period (332 nmol/kg). Covariations between salinity and [Ba] confirm the non-conservative behavior of barium during all three seasons. The salinity-[Ba] trends show barium removal in the low-salinity regions, attributable to its authigenic scavenging onto Fe-Mn oxyhydroxides. Mass balance calculations show that the relative contribution of barium via rivers (~18%), (freshwater) submarine groundwater discharge (SGD; ~25%), and desorption from particulate matters (~19%) to the lagoon during pre-monsoon seasons is nearly the same. During the monsoon season, the SGD supply of barium decreases to ~2%, whereas riverine (~20%) and desorption (~24%) contributions remain similar to that observed during the pre-monsoon. The sediment chemistry (Mg, Al, Fe) data and their correlations with Ba concentrations reveal that the desorptive release of barium to the lagoon is mainly via its cationic replacement from the suspended sediments by seawater Mg. In addition to these sources, our results show that about half of the dissolved barium during pre-monsoon and monsoon seasons remains unaccounted and may have been supplied by an additional source, which may be linked to subsurface supply of recirculated seawater and/or organic matter remineralization. Our quantitative approach emphasizes the importance of these additional sources in regulating the coastal barium inventory.

钡 (Ba) 的丰度和分布可作为海洋生物地球化学过程的可靠代表。然而，它在沿海地区的循环受到多种源/汇的复杂调节。在这项研究中，溶解的钡的浓度在一个大的空间分布沿海泻湖（Chilika泻湖，印度）和它的源水已经研究了三种不同的季节（预季风（2017年五月），季风（2017年8月），和后-季风（2018 年 1 月））。此外，床层和悬浮沉积物中 Ba 和其他元素的含量还研究了它们的不同部分（散装、粘土和可交换）。这些数据用于限制沿海过程以调节沿海 Ba 清单。孟加拉湾的溶解 [Ba]（中值 ~ 37 nmol/kg（范围：30–53 nmol/kg））低于河流观测值（中值 ~ 319 nmol/kg（范围：256–583 nmol） /kg)）和地下水（中位数 ~ 464 nmol/kg（范围：20–4428 nmol/kg））样本。季风前 (1052 nmol/kg) 和季风 (652 nmol/kg) 季节的 Chilika 泻湖的盐度加权钡浓度高于季风后时期 (332 nmol/kg)。盐度和 [Ba] 之间的协变证实了钡在所有三个季节中的非保守行为。盐度-[Ba]趋势显示在低盐度地区去除钡，归因于它对 Fe-Mn 羟基氧化物的自生清除。质量平衡计算表明，钡通过河流（~18%）、（淡水）海底地下水排放（SGD；~25%）和颗粒物解吸的相对贡献(~19%) 到季风前季节的泻湖几乎相同。在季风季节，钡的 SGD 供应量减少至约 2%，而河流（约 20%）和解吸（约 24%）贡献与季风前观察到的相似。沉积物化学（Mg、Al、Fe）数据及其与 Ba 浓度的相关性表明，钡向泻湖的解吸释放主要是通过海水 Mg 从悬浮沉积物中的阳离子置换。除了这些来源，我们的研究结果表明，在季风前和季风季节，大约一半的溶解钡仍然下落不明，可能是由其他来源提供的，这可能与再循环海水和/或有机物的地下供应有关再矿化。我们的定量方法强调了这些额外来源在调节沿海钡库存方面的重要性。