Abstract

The data of shipboard measurements of oxygen concentration at international monitoring stations in the Baltic Sea were used to assess the year-to-year variations of oxygen regime in the late XX–early XXI century (1989–2017). The obtained results were compared with similar studies in 1951–1988. The water areas with hypoxic conditions were found to increase as well as their vertical development. The deterioration of oxygen regime was most considerable in the Gulf of Finland. While in the previous 30 years (1959–1988), hypoxic conditions were recorded only in the western part of the gulf and not in all years, since 1993, hypoxic zones were recorded here every year, developing eastward and appearing more and more often in its central and eastern parts. The analysis of variations of temperature and salinity revealed an increase in the difference between seawater densities in the surface and bottom layers of the Baltic Sea. An assumption was made that the deterioration of the oxygen regime in the Baltic Sea in the recent decades could be due to a stronger stratification of sea water masses.

中文翻译：

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二十世纪末至二十一世纪初波罗的海缺氧区的动力学

摘要

波罗的海国际监测站的船上氧气浓度测量数据被用于评估20世纪末至二十一世纪初（1989-2017年）的氧气状况逐年变化。将获得的结果与1951–1988年的类似研究进行比较。发现缺氧条件下的水域面积及其垂直发展都在增加。芬兰湾的氧气状况恶化最为严重。在过去的30年（1959–1988年）中，仅在海湾的西部地区记录了缺氧情况，而并非在所有年份中都记录到了缺氧情况，自1993年以来，这里每年都记录有缺氧区域，向东发展，并在越来越多的地方出现。它的中部和东部。对温度和盐度变化的分析表明，波罗的海表层和底层的海水密度之间的差异有所增加。据推测，近几十年来波罗的海的氧气状况恶化，可能是由于海水团块的分层更强。