Introduction. Marine aquatic organisms, especially with nutritional value, accumulate pollutants from the environment and therefore must be constantly monitored for toxic elements content. Mercury, even in inorganic form and in sub-lethal amounts, is a risk factor for aquatic biota. The aim of the work is to measure mercury concentrations in the tissues of the Black Sea gobies; identification of species accumulating mercury to a greater or lesser extent, as well as intraspecific features of mercury accumulation. Material and methods. Muscles, liver and gills of Black Sea goby fish (round goby Neogobius melanostomus, niger-goby Gobius niger, knout goby Mesogobius batrachocephalus, caught in 2019–2020) were used as material for the study of mercury concentration. The population parameters of the fish caught in the bays of the Sevastopol were analyzed, and then the organs were prepared for the study of the mercury content in them using the atomic absorption method. Food objects were also examined using a binocular microscope. Results and discussion. Mercury was detected in all analyzed samples, but the concentrations observed in fish tissues are below the legal level of sanitary and hygienic standards for marine fish (0.5 mg/kg). The average concentrations of mercury in the liver of different species of gobies exceeded the concentration of mercury in the gills, with the exception of the round goby. On average, the knout goby accumulates more mercury than the round goby and the black goby. In M. batrachocephalus, unlike other species of Gobiidae, a correlation was found between age and mercury concentration in fish organs: high correlation in muscles (0.7 < r = 0.75), significant r — in gills and liver. The connection between the standard length of species analyzed and the concentration of mercury is characterized as: middle — in the gills, high — in the liver. The revealed differences in the cumulative capacity of the objects studied are associated with different nutritional preferences. Almost all the intestines of the toad (knout) goby at the time of capture were empty, which indicates a faster digestion of food objects, as well as the coincidence of the time of capture with a long starvation associated with spawning and protection of eggs laying. Consequently, in this species, the main “load” falls on the gills, which indicates the route of toxicant entry into the body mainly through respiration, and not through food chains. In round goby, the toxicant studied, on the contrary, enters through food objects — bivalve mollusks. The black goby has the widest food spectrum; values of mercury content, comparable with other species of Gobiidae, are associated with the natural accumulation of the toxicant (with age), partial ingress of mercury through food chains. Conclusion. Mercury concentrations in different tissues of gobies did not exceed the legal standard for marine fish. The average values of mercury concentration in the liver of different gobies exceeded those in the gills, with the exception of N. melanostomus. On average, the toad goby accumulates more mercury than other species of Gobiidae. A relationship was found between the standard length of the goby and the concentration of mercury: in the gills — moderate, in the liver — significant. The studied fish species can be considered as suitable indicators of mercury pollution in the Sevastopol bays. Limitations. When studying the level of mercury accumulation in the tissues of the Black Sea gobies from the coastal zone of the Sevastopol, 137 samples, and at ichthyological analyze — 190 round goby, 50 knout goby, 20 niger goby were done, which is a sufficient sample volume to describe the degree of toxicity of different fish tissues, as well as the mechanisms of mercury accumulation.

Of significant scientific and public concern is the high toxicity, significant bioaccumulation, and magnified concentration within the food web of mercury (Hg). Hg content both dissolved and in suspended forms in water as well as in biomass of different hydrobiont taxa was studied in 18 saline lakes in Crimea from 2012 to 2021. The impact of different factors (salinity, seasonality, anthropogenic activities, geological background, etc.) was analyzed. The generalization of data for all lakes showed that the average concentration of Hg in dissolved form was 129 ng L−1, varying over a wide range. The content of Hg in total suspended substrates was an average of 151 ng L−1, and the total content of Hg in lake water averaged 291 ng L−1. Geological background and anthropogenic activities can determine the total Hg content in lakes. In most lakes, a significant positive correlation was noted between the concentration of one, two, or all three indicators of Hg content and the month of the year, with indicators increasing from winter through to autumn. When analyzing the entire data array, a significant positive correlation was found between the concentration of the suspended form of Hg and salinity; such correlation between the concentration of the dissolved form of Hg and salinity was absent. The highest average Hg concentrations in biomasses were noted in Artemia and were the lowest in plants. Geological background and human activity contribute to high Hg content in lakes. Hydrobionts can significantly influence the distribution and behavior of Hg, being an important factor of its cycle in the lakes.

As a result of sedimentation, suspended particles carry chemical pollution from the surface layer of water into bottom sediments, playing a significant role in waters' self-purification from mercury. For the purpose of establishing the features of mercury distribution in the surface water of coastal and open-sea areas and concentrating it in the suspended matter, mercury concentrations were measured in water sampled in different seasons of the years 2018-2019 from the surface water layer of the Black Sea, and empirical dependencies of the parameters of mercury concentrating by the suspended matter on the seasons and depths of the water areas were determined. It is demonstrated that dissolved mercury forms dominated in the Black Sea during the period under investigation, regardless of the seasons. The concentration of dissolved mercury form in the water of the Black Sea varied from 10.0 to 130.0 ng/L, and the average concentration was 54.9 ng/L. The coefficient of mercury accumulation by suspended matter (K-ss) was determined, which varied within the range (0.01-3.33) . 10(6). The values K-ss > 10(6) provide evidence of the high concentrating capacity of suspended matter in sea water and prevalence of sedimentation over other biogeochemical mechanisms of water self-purification. The formula for calculating the percentage pool of mercury in suspended matter was analysed. The values of the percentage pool of the suspended form of mercury were obtained, ranging from 3.2 to 75 % of the total mercury content in the surface water of the Black Sea for its coastal and open water areas in different seasons of the year.

There are few studies on mercury content in hypersaline waters. Mercury content was studied in Bay Sivash (the Sea of Azov), the world’s largest hypersaline lagoon with a strong salinity gradient from 36 to 90 g l−1. The dissolved mercury compounds ranged from 120 to 250 ng l−1, Hg varied from 60 to 450 ng l−1 in the suspended matter, and total mercury in the water ranged from 200 to 600 ng l−1. Salinity and the total suspended matter had practically no effect on the amount of dissolved and suspended forms of mercury separately, but their growth significantly increased total mercury content in water. Only the concentration of dissolved forms of mercury in water significantly correlated with dissolved organic matter. The Hg concentration in the bottom sediments averaged 13.8 ng g−1 wet weight. Both high salinity and human activities on the Sivash drainage area are responsible for high Hg content in lagoon water.

The condition of marine organisms mirrors the impact that natural or anthropogenic factors have on them, hence results of an analysis of the mercury content in fish, for example, can help to assess the pollution of sea water with this element. In this study, organs of 86 fish caught in four Sevastopol bays: Karantinnaya, Streletskaya, Kruglaya and Balaklavskaya, were analyzed. Scorpion fish (Scorpaena porcus Linnaeus, 1758) was chosen for research because it is a rather inactive fish, staying close to the sea bottom, which can help to evaluate the degree of mercury pollution in the Sevastopol bays. The purpose of the work was to investigate the distribution of mercury in the liver and gills of Black Sea scorpion fish of different sex and age. Mercury in samples was determined by atomic absorption spectrometry (AAS). The study showed that the concentration of mercury in the liver exceeded the concentration of mercury in the gills in fish from all the bays studied. The highest concentration, exceeding the legal limit (500.00 ng g(-1)), was recorded only in the liver of one female (752.6 ng g(-1)) and the liver of one male from Streletskaya Bay (571.4 ng g(-1)). In addition, the average concentration for females and males was approximately the same: 168.4 ng g(-1) and 169.2 ng g(-1), respectively. The absolute concentration of mercury in the liver of all scorpion fish from Streletskaya Bay varied in the range 22.73-752.6 ng g(-1), with an average of 167.7 ng g(-1). In the bays of Karantinnaya, Kruglaya and Balaklavskaya, the concentration of mercury in the fish liver did not exceed the permissible level, varying from 22.18 to 395.8 ng g(-1). The highest content of mercury in the liver of Scorpaena porcus from Streletskaya Bay may be associated with he developed infrastructure and shipping, which pollute the water area.

The ability of suspended matter to concentrate mercury may be the prevailing factor in Black Sea purification. As a result of sedimentation, suspended particles transport pollution from the surface layer of the water column and, as a consequence, can deposit them in bottom sediments, thus participating in self-purification of marine area. Suspended matter, as a dispersed phase of an aqueous medium, considered as a heterogeneous dispersed system, can be more saturated with mercury than water itself, as a dispersion medium. In this work, contribution of dissolved and suspended forms of mercury to its total content was determined, and concentrating ability of suspended matter relative to mercury, which affects biogeochemical self-purification of waters from mercury, was estimated. All water samples were separated into filtrate and suspension by filtration through nucleopore filters with a pore diameter of 0.45 μm. Measurements of mercury concentration were carried out using a Hiranuma-1 analyzer by the method of atomic absorption spectrophotometry. Concentration of dissolved mercury in water was determined per liter, while in suspended matter – per liter and per gram of dry weight. Prevalence of dissolved form of mercury was revealed regardless of the season, with its percentage varying from 66.3 to 85.8 % of total mercury concentration. Average content of suspended form varied in the range of 14.2–33.7 % of its total form. Values of the dry weight of suspended matter (mss) varied from 0.1 to 15.0 mg·L−1 over the entire period studied, and an accumulation coefficient of mercury in suspended matter (Kss) varied from n·10³ to n·107. Significant contribution of suspended form of mercury in sea foam to its total content in stormy weather was established. With dry weight of suspended matter in seawater reaching 9.6 mg·L−1, the concentration of dissolved form of mercury reached 55 ng·L−1, and the concentration of suspended one reached 20 ng·L−1. In sea foam, the concentration of suspended sedimentary matter was of 895.2 mg·L−1; mercury concentration reached 200 ng·L−1 in dissolved form and 260 ng·L−1 in suspended one. Total mercury concentration in sea foam in this case exceeded the threshold limit value (100 ng·L−1) for seawater. The accumulation coefficient of mercury in suspended matter (Kss) was 3.8·104 for seawater and 1.5·103 for foam. Such distribution of mercury in sea suspension, foam, and water, as well as Kss values obtained, may indicate high significance of suspended matter in self-purification of marine area. At a low mercury content in water, the concentrating ability of suspended matter, characterized by relatively high values of its mercury accumulation coefficient, becomes a very significant factor in the sedimentation self-purification of waters from mercury; however, with an increase in water pollution with mercury, the effect of this factor decreases.

Способность взвешенного вещества концентрировать ртуть может быть превалирующим фактором в очищении водной толщи Чёрного моря. В результате седиментации взвешенные частицы выносят загрязнения из поверхностного слоя воды и в итоге могут депонировать их в донных осадках, участвуя таким образом в процессах самоочищения морской акватории. Взвешенное вещество как дисперсная фаза водной среды, рассматриваемой в качестве гетерогенной дисперсной системы, может быть более насыщено ртутью, чем сама вода как дисперсионная среда. В данной работе определён вклад растворённой и взвешенной форм ртути в её общее содержание и оценена концентрирующая способность взвешенного вещества в отношении ртути, обуславливающая биогеохимическое самоочищение вод от ртути. Все пробы воды разделяли на фильтрат и взвесь путём их фильтрации через нуклеопоровые фильтры с диаметром пор 0,45 мкм. Измерения содержания ртути проводили на анализаторе «Хиранума-1» методом атомно-абсорбционной спектрофотометрии. Концентрацию растворённой ртути в воде определяли в пересчёте на литр, а во взвешенном веществе — на литр и на грамм сухой массы. Выявлено превалирование растворённой формы ртути независимо от сезона года с варьированием её процентного содержания в диапазоне 66,3–85,8 % от общей (суммарной) концентрации ртути. Средняя концентрация взвешенной формы составила 14,2–33,7 % от её общего содержания. При этом значения концентрации взвешенного вещества (mвзв) варьировали от 0,1 до 15,0 мг·л−1 за весь исследованный период, а коэффициент накопления ртути взвешенным веществом (Кнвзв) изменялся в диапазоне от n·10³ до n·107. Определён значительный вклад взвешенной формы ртути в её общее содержание в морской пене, образованной в штормовую погоду. Так, при концентрации взвешенного вещества в морской воде 9,6 мг·л−1 концентрация растворённой формы ртути имела значение 55 нг·л−1, а взвешенной — 20 нг·л−1. В морской пене концентрация взвешенного осадочного вещества составила 895,2 мг·л−1, а концентрация ртути достигла 200 нг·л−1 в растворённой форме и 260 нг·л−1 — во взвешенной. Содержание общей (суммарной) ртути в морской пене при этом превышало предельно допустимую концентрацию (100 нг·л−1) для морской воды. В данном случае Кнвзв для морской воды был равен 3,8·104, а для пены — 1,5·103. Такое распределение ртути в морской взвеси, пене и воде, а также полученные значения коэффициента накопления свидетельствуют о большой важности взвешенного вещества в самоочищении морской акватории. При низком содержании ртути в воде концентрирующая способность взвешенного вещества, характеризуемая относительно высокими значениями его коэффициента накопления ртути, становится весьма значимым фактором в седиментационном самоочищении вод от ртути, однако при повышении загрязнения вод ртутью влияние этого фактора снижается.

По результатам измерений концентрации ртути в пробах воды, отобранных в весенний период в 2012-2017 гг.в акватории Крымского шельфа Чѐрного моря, были определены зависимости концентрирования ртути взвешенным веществом.Зарегистрирован тренд насыщения взвесей ртутью при повышении ее концентрации в воде.Определены коэффициенты накопления ртути взвесями и установлено, что зависимость коэффициентов накопления от изменения концентрации ртути в воде Крымского шельфа Черного моря описывается уравнением Фрейндлиха, а также с меньшей степенью достоверности уравнением Ленгмюра.Определено, что превалирующим фактором седиментационного самоочищения вод в

Работа посвящена изучению характеристик седиментационного самоочищения вод Севастопольской бухты от радиоактивных и консервативных химических загрязняющих веществ. На примере распределения 90Sr, 137Cs, 239,240Pu, 210Po, Hg, ΣПХБ5 и ΣДДТ в поверхностном слое донных осадков в различных акваториях бухты показано, что характеризуемая коэффициентом накопления концентрирующая способность живого и косного вещества в отношении контаминантов является одним из значимых факторов реализации биогеохимического механизма самоочищения вод. Воздействие седиментационных процессов направлено на поддержание радионуклидного и химического гомеостаза морских экосистем по принципу Ле Шателье — Брауна. Установлено, что в современных условиях приоритетными загрязнителями воды и донных отложений Севастопольской бухты являются Hg, ΣПХБ5 и ΣДДТ.