The study aimed to determine the level of mercury (Hg) and its labile and stable forms in the surface sediments of the Baltic Sea. The work considers the impact of current and historical sources of Hg on sediment pollution, together with the influence of different environmental parameters, including water inflows from the North Sea. Surface sediments (top 5 cm) were collected in 2016–2017 at 91 stations located in different areas of the Baltic Sea, including Belt Sea, Arkona Basin, Bornholm Basin, Gdańsk Basin, West Gotland Basin, East Gotland Basin, and the Bothnian Sea. Besides, the particulate matter suspended in the surface and near-bottom water was also collected. The analysis of total Hg concentration and individual Hg forms in collected samples was carried out using a 5-step thermodesorption method. This method allows for the identification of three labile and thus biologically available, fractions of Hg, which are mercury halides, organic Hg, mercury oxide and sulphate. Two stable fractions, mercury sulphide and residual Hg, were also determined. The highest Hg concentrations, reaching 341 ng g⁻¹, were measured in the highly industrialised Kiel Bay, which was additionally a munition dumping site during and after World War II. High Hg level, ranging from 228 to 255 ng g⁻¹, was also recorded in the surface sediments of the Arkona Basin, which was a result of the cumulative effect of several factors, such as deposition of Hg-rich riverine matter, favourable hydrodynamic conditions and military activities in the past. The relatively elevated Hg concentrations, varying from 60 to 264 ng g⁻¹, were found in the Gdańsk Basin, a region under strong anthropopressure and dominated by soft sediments. The sum of labile Hg in sediments was high and averaged 67% (with the domination of organic Hg compounds), which means that a large part of Hg can be released to the water column. It was found that the water inflows from the North Sea intensify the remobilisation of Hg and its transformation into bioavailable labile forms. As a consequence, the load of Hg introduced into the trophic chain can increase. Despite the significant reduction of Hg emission into the Baltic in the last decades, surface sediments can be an important secondary Hg source in the marine ecosystem. This is especially dangerous in the case of the western Baltic Sea.

该研究旨在确定波罗的海表层沉积物中汞 (Hg) 的含量及其不稳定和稳定形式。这项工作考虑了当前和历史汞来源对沉积物污染的影响，以及不同环境参数的影响，包括来自北海的水流入。 2016年至2017年在波罗的海不同区域的91个站收集了表层沉积物（顶部5厘米），包括贝尔特海、阿科纳盆地、博恩霍尔姆盆地、格但斯克盆地、西哥特兰盆地、东哥特兰盆地和波的尼亚海。此外，还收集了悬浮在地表和近底层水中的颗粒物。使用五步热解吸法对收集的样品中的总汞浓度和单个汞形态进行分析。该方法可以鉴定三种不稳定且具有生物活性的汞组分，即卤化汞、有机汞、氧化汞和硫酸汞。还测定了两种稳定的组分：硫化汞和残余汞。在高度工业化的基尔湾测得汞浓度最高，达到 341 ng g ^-1 ，该湾在二战期间和战后也是一个弹药倾倒场。阿科纳盆地表层沉积物中也记录了高汞含量，范围为 228 至 255 ng g ⁻¹ ，这是多种因素累积作用的结果，例如富含汞的河流物质的沉积、有利的水动力过去的情况和军事活动。在格但斯克盆地发现了相对较高的汞浓度，从 60 到 264 ng g ^-1不等，该地区处于强烈的人类压力下，以软沉积物为主。 沉积物中的不稳定汞总量较高，平均为67%（以有机汞化合物为主），这意味着很大一部分汞可以释放到水体中。研究发现，从北海流入的水加强了汞的再利用，并将其转化为生物可利用的不稳定形式。因此，引入营养链的汞负荷会增加。尽管过去几十年波罗的海的汞排放量大幅减少，但表层沉积物可能是海洋生态系统中重要的次生汞源。对于波罗的海西部来说，这尤其危险。