Mercury loads into the sea associated with extreme flood

The impact of global climate changes on trace and rare earth elements mobilization in emerging periglacial terrains: Insights from western shore of Admiralty Bay (King George Island, Antarctic)

In the rapidly changing climate, the biogeochemical behaviours of trace elements and Rare Earth Elements (REEs) in emerging periglacial environments assumes profound importance. This study provides pivotal insights into this dynamic by investigating the Antarctic's response to global climate change. The bedrock of King George Island is rich in REEs, with the presence of trace metals (TEs), with the highest concentrations of metals found in ornithogenic soil (∑REE 84.01-85.53 mg∙kg-1 dry weight). REEs in the studied soil, found mainly in igneous rocks, as is indicated by the positive correlation of these elements with sodium and calcium. The TEs released as a result of weathering are leached by water flowing down local watercourses to Admiralty Bay, as indicated by the decreasing results of ∑REE = 11.59 μg∙dm-3 in watercourse water, ∑REE = 1.62 μg∙dm-3 in watercourse pools and ∑REE = 0.66 μg∙dm-3 in the water of Admiralty Bay at the outlet of the watercourse. Water originating from the melting of snow on the glacier also carried REEs (∑REE = 0.14 μg∙dm-3), a fact which suggest the further influx of these elements from atmospheric deposition. The Prasiola crispa turned out to be the most susceptible to the accumulation of REEs (∑ 80.73 ± 5.05 μg g-1) and TEs, with the exception of chromium and zinc, whose concentrations were found to be at their highest in Deschampsia antarctica. In Usnea antarctica, Xanthoria candelaria, and Ceratodon purpureus and Politrichastrum alpinum, a dominant role in the accumulation of REEs was played by HREEs. The determined enrichment factor (EF) indicates that the soil cover is a source of REEs (EFAlgae for ∑REE = 5.07; EFLichen for ∑REE = 6.65; EFBryophyta for ∑REE = 5.04; EFVascular for ∑REE = 4.38), while Ni, As and Pb accumulated in plants may originate from other sources than the soil.

Mercury dynamics at the base of the pelagic food web of the Gulf of Gdańsk, southern Baltic Sea

Planktonic organisms, which have direct contact with water, serve as the entry point for mercury (Hg), into the marine food web, impacting its levels in higher organisms, including fish, mammals, and humans who consume seafood. This study provides insights into the distribution and behavior of Hg within the Baltic Sea, specifically the Gulf of Gdańsk, focusing on pelagic primary producers and consumers. Phytoplankton Hg levels were primarily influenced by its concentrations in water, while Hg concentrations in zooplankton resulted from dietary exposure through suspended particulate matter and phytoplankton consumption. Hg uptake by planktonic organisms, particularly phytoplankton, was highly efficient, with Hg concentrations four orders of magnitude higher than those in the surrounding water. However, unlike biomagnification of Hg between SPM and zooplankton, biomagnification between zooplankton and phytoplankton was not apparent, likely due to the low trophic position and small size of primary consumers, high Hg elimination rates, and limited absorption.

Mercury distribution in the coastal zone of Central Chile, Southeast Pacific: A comprehensive assessment of seawater, sediment, and biota

This study examines the mercury content in the marine matrices water column, surface sediment and benthic invertebrates of Coronel and Coliumo bays, central Chile, under winter and summer conditions. Coronel Bay has been subject to intense industrialization in the last three decades, while Coliumo Bay remains as a fisherman's cove and a popular summer tourism destination. Our results reveal significantly higher mercury concentrations in the three environmental matrices analyzed for Coronel Bay, while Coliumo Bay exhibits levels within the range considered natural. Moreover, the mercury levels in Coronel Bay exceed the optimal criteria for aquatic life, indicating a deterioration in environmental quality of this locality. Industrial development is identified as main factor explaining the differences observed between these two coastal water bodies. This study presents the most updated record of mercury levels in the Southeast Pacific and represents the first comprehensive evaluation of marine environmental matrices in two bays with divergent activities.

Factors determining bioaccumulation of neurotoxicant Hg in the zebra mussels (Dreissena polymorpha): Influence of biometric parameters, sex and storage of shell

One of benthic organisms exposed to contact with mercury in the southern Baltic is alien species of clam: Dreissena polymorpha. As this organism is increasingly dynamic in various regions of the world including the southern Baltic region, it is reasonable to ask whether it tolerates elevated concentrations of xenobiotics? Does it effectively eliminate Hg? The study determined the effects of biometric parameters and water temperature on the rate of accumulation and efficiency of eliminating Hg from body. Investigations focused on the shell which represents poorly-recognized role in the process of Hg distribution in clams. The results showed that especially during warm season, clams effectively reduced the levels of Hg in their body by the biodilution of Hg and reproduction. Important factor influencing detoxification was Hg transfer from the soft tissue to the shell. This protects the soft tissue against the toxic effect of Hg.

Mobility and bioavailability of mercury in sediments of the southern Baltic sea in relation to the chemical fractions of iron: Spatial and temporal patterns

Marine sediments play a significant role as reservoirs for mercury (Hg), a bioaccumulative toxic pollutant that poses risks to human and ecosystem health. Iron (Fe) has been recognized as an influential factor in the complexation and bioavailability of Hg in sediments. However, limited studies have investigated the interactions between the chemical fractions of these elements in natural settings. This study aims to examine the fractions of Hg and Fe in sediments of the Baltic Sea, a region historically impacted by Hg pollution. The Hg fractions were determined using the thermodesorption technique, while sequential extraction was employed to identify the Fe fractions. The findings confirm the crucial role of Fe in the formation, as well as the horizontal and vertical distribution of labile and stable Hg in marine sediments. Factors such as the contribution of organic matter, the presence of reactive Fe, and Fe associated with sheet silicates emerged as significant drivers that positively influenced the content of the most labile Hg fractions, potentially affecting the mobility and bioavailability of Hg in the marine environment.

Atmospheric mercury in forests: accumulation analysis in a gold mining area in the southern Amazon, Brazil

The spatial distribution and dispersion of mercury (Hg) is associated with the structural conditions of the environment, primarily land use and vegetation cover. Man-made emissions of the metal from activities such as artisanal and small-scale gold mining (ASGM) can influence this distribution. Forest ecosystems are of particular importance as they constitute one of the most active environments in the biogeochemical cycle of Hg, and understanding these dynamics is essential to better understand its global cycle. In this study, we determined the content of Hg present in different forest strata (soil, leaf litter, herbaceous, underwood/bush, and arboreal), as well as the relationship between the presence of Hg and the landscape heterogeneity, percentage of gold mines, and ground slope. This study was carried out in tropical forest areas of the southern Brazilian Amazon. Accumulation and transport of Hg between forest strata was assessed in order to understand the influence of these forest environments on Hg accumulation in areas where ASGM occurs. We verified that there is a difference in Hg content between forest strata, indicating that atmospheric Hg is accumulated onto the arboreal stratum and transported vertically to strata below the canopy, i.e., underwood/bush and herbaceous, and subsequently accumulated in the leaf litter and transferred to the soil. Leaf litter was the stratum with the highest Hg content, characterized as a receptor for most of the Hg load from the upper strata in the forest. Therefore, it was confirmed that Hg accumulation dynamics are at play between the areas analyzed due to the proximity of ASGMs in the region. This indicates that the conservation of forest areas plays an important role in the process of atmospheric Hg deposition and accumulation, acting as a mercury sink in areas close to man-made emissions.

Different pathways of accumulation and elimination of neurotoxicant Hg and its forms in the clam Atlantic rangia (Rangia cuneata)

Mercury (Hg) is one of the most hazardous environmental pollutants, negatively affecting the ecosystem. The pathways of Hg elimination are well recognized in organisms from higher trophic levels compared to invertebrates such as clams. The aim of this study was to identify pathways of Hg accumulation in an alien species clams: Rangia cuneata, which represented an unrecognized source of Hg into the trophic chain of the southern Baltic Sea. An important aspect of this study was to determine Hg detoxification processes based on physiological state and biometric parameters of the atlatntic rangia. Special consideration was given to the role of shell in this process and the form of Hg in which it occurred. The study was also considered in terms of geographical changes in the Hg concentration in clams and the factors involved. Sex did not determine the concentration of Hg and its fraction in clams soft tissue and shell. Clams detoxified xenobiotic effectively in summer when their metabolism was accelerated. As a result, clams grew faster in warmer water than they accumulated Hg. In addition, this process was intensified by their reproduction. The mass of accumulated mercury was higher in the shell mass than in the body mass in summer. Transfer of Hg from the body to the shell depended on the forms Hg, mostly HgS. Geographical changes in the mercury concentration in clams was related to the form of Hg in the sediment. In areas where were more fines sediment fraction and organic matter accumulated in the sediment, mercury was present in a less bioavailable form, which caused that clams had lower Hg concentrations in their body. With assumption that in the future, due to its increasingly frequent occurrence, atlatntic rangia will become more common component of fish diet, a smaller load of toxic mercury will be introduced to the marine trophic chain.

Mercury in the Polish part of the Baltic Sea: A response to decreased atmospheric deposition and changing environment

Our review of the literature showed that since the beginning of the socio-economic transformation in Poland in the 1990s, the downward trend in Hg emissions and its deposition in the southern Baltic Sea was followed by a simultaneous decrease in Hg levels in water and marine plants and animals. Hg concentrations in the biota lowered to values that pose no or low risk to wildlife and seafood consumers. However, in the first decade of the current century, a divergence between these two trends became apparent and Hg concentrations in fish, herring and cod, began to rise. Therefore, increasing emission-independent anthropogenic pressures, which affect Hg uptake and trophodynamics, remobilization of land-based and marine legacy Hg deposits, as well as the structure of the food web, can undermine the chances of reducing both the Hg pool in the marine environment and human Hg exposure from fish.

Temporal trends of mercury levels in fish (dab, Limanda limanda) and sediment from the German Bight (North Sea) in the period 1995-2020

As a toxic and harmful global pollutant, mercury (Hg) enters the marine environment through natural sources, and human activities. It bioaccumulates through the food chain and therefore, Hg is of great importance for environmental monitoring. This study aims to answer the question if Hg contamination in fish and sediment from the German Bight follows temporal trends. Therefore, 496 individual female dab (Limanda limanda) were analyzed. The Hg concentrations in the muscle of dab from the German Bight showed significant increase in function of time with an annual percental change of 1.4%, leading to a 41% increase in Hg contamination level within 25 years of monitoring. At the same time, Hg concentrations in sediment-analyzed in 86 samples-significantly decreased in the nearby North Sea environment. This surprising contradiction is shown in the present study and possible causes are discussed. It could be clearly shown that contamination in sediment and biota can follow completely different time courses and therefore, different environmental matrices should be considered in future monitoring studies. Age of the fish turned out to be a biological factor of particular importance for temporal trend analysis.

Trace elements in the muscle, ova and seminal fluid of key clupeid representatives from the Gdansk Bay (South Baltic Sea) and Iberian Peninsula (North-East Atlantic)

BACKGROUND

Baltic herring and European sardine are pelagic, fish of particular ecological importance, on the one hand control numbers of planktonic organisms, and on the other hand exist as food for predators on higher trophic levels. Moreover, these fish are among the main species caught for human consumption. Rare earth elements (REEs) come mainly from geogenic sources but, due to their use in technology, agriculture and medicine, the importance of anthropogenic sources is growing steadily.

METHODS

Samples used for the study were available on the market. Fresh materials of fish muscle, ova and seminal fluid were mineralized and elements were determined by means of inductively coupled plasma - mass spectrometry (ICP-MS).

RESULTS

The conducted research indicated the presence of REEs in the muscles of the Baltic herring (∑REE = 0.076 ± 0.047 mg/kg) and European sardine (∑REE = 0.191 ± 0.163 mg/kg), with a clear dominance of heavy REEs in both fish species. Trace elements (TE) in the muscles of the tested fish demonstrated a similar system of concentration (Baltic herring: Zn > As > Se > Cu > Cr > Ni > Pb > Cd; European sardine: Zn > As > Se > Cu > Ni > Cr > Pb > Cd). REEs and TEs in these fish were presence in ova and seminal fluid indicates intergenerational transfer.

CONCLUSION

Changes in the concentrations of some trace elements (As, Cu, Cd) in the muscles of herring indicate increases compared to the historical data. The availability of metals in the aquatic environment may be determined by ongoing climate changes, effected water salinity and warming increased availability of labile forms of trace metals. Decline trends in the condition of pelagic fish need to extend the research in the context of contemporary environmental threats.

The impact of sediment, fresh and marine water on the concentration of chemical elements in water of the ice-covered lagoon

The common use of chemical elements by man has been contributing to their extraction for centuries. As a consequence, they have been directly or indirectly introduced into the biogeochemical cycle. In the framework of many conventions, mining and processing of elements are currently subject to many restrictions. However, their large load that has already been deposited in the soil and bottom sediments can be remobilised and enter the food chain. The identification of factors favouring this process is very important, especially during the period of adopting new legal regulations on limiting the emission of pollutants. It became possible in February 2018 during the persistence of ice cover on the lagoon's surface. This allowed observation of processes, the effect of which in the absence of ice is blurred by wind mixing water. Therefore, an investigation of sources of 25 elements in a lagoon of the southern Baltic has been undertaken, based on the example of the Vistula Lagoon. The results point to the remobilisation of chemical elements (including the toxic ones) from land and bottom sediments, where they have been deposited for decades. These processes led to the accumulation of metals in certain areas of the lagoon. It may result in their uptake and accumulation in the benthic organisms inhabiting the lagoon and further transfer in the food chain. It is of major importance as the lagoons in the southern Baltic fulfil many essential functions in the scope of tourism, economy, and fishery. Thanks to restrictions on the quality of wastewater and the emission of pollutants, it has been noticed a substantial "purifying" effect of rivers, too.

Status and trends of mercury pollution of the atmosphere and terrestrial ecosystems in Poland

The goal of this paper is to assess the current status and trends of total mercury (THg) contamination of the atmosphere and terrestrial ecosystems in Poland. The study shows that the reduced domestic and worldwide atmospheric emission of Hg resulted in decreased THg level in the terrestrial biotope and biosphere. Considering that Poland is one of the main Hg emitters in Europe, the THg concentrations in its abiotic environment are still elevated. However, the THg level in terrestrial organisms is relatively low, which is because a large proportion of Hg deposited on land is accumulated in organic-rich soils. Regarding the THg concentration, consumption of wildlife and livestock from Poland is safe for humans. Nevertheless, the authors indicate the need for effective environmental monitoring, based on selected bioindicators, which is crucial considering the slowing reduction of Hg emission combined with the consequences of the changing climate.

Distribution and bioavailability of mercury in the surface sediments of the Baltic Sea

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.

Presence of mercury and methylmercury in Baltic Sea sediments, collected in ammunition dumpsites

Methylmercury (MeHg) is the most toxic and dangerous form of mercury occurring in the environment. MeHg is highly bioaccumulative in organisms and undergoes biomagnification via the food chain. In the Baltic Sea munition dumpsites, methylmercury can be formed from mercury fulminate contained in primary explosives, as environmental conditions there favour methylation. MeHg in analysed sediments ranged from 19 to 2362 pg g^-1d.w., the concentration of mercury (Hg_TOT) ranged from 4 to 294 ng g^-1 d.w., and the values of MeHg/Hg ratio ranged from 0.1 to 2.0%. The obtained results confirmed that munition dumpsites are a source of mercury. The concentration of MeHg is elevated in a wider area than immediately next to dumped munitions. Presented results suggest that physical processes responsible for sediment and near-bottom water movement are diffusing MeHg signal, making munition dumpsites rather a diffuse source of MeHg than a number of point sources associated with particular munitions.

Spatial and Temporal Trends in Contamination of the Czech Part of the Elbe River by Mercury Between 1991 and 2016

We summarized available data concerning contamination of the Czech part of the Elbe River by mercury and assessed the potential risks to humans connected with the consumption of contaminated fish. Total mercury concentrations were evaluated in dorsal muscle of chub (Squalius cephalus) and bream (Abramis brama) that were collected at 11 sampling sites in the period from 1991 to 2016. Significant differences among sites were found for both species. The highest contamination was observed near the non-ferrous Kovohute metal works at Celakovice and also downstream from the Spolana chemical plant at Neratovice. A significant decline in contamination with time (concentrations decreasing from 1.65 to 0.22 mg kg^-1; p = 0.004) was revealed in chub downstream from the Spolana plant. Calculated hazard indices (HIs) were below 1, therefore, adverse health effects on the general Czech population connected with the consumption of fish from the Elbe River were not expected.

Could biotransport be an important pathway in the transfer of phenol derivatives into the coastal zone and aquatic system of the Southern Baltic?

Bird guano and the faeces of marine mammals appear to be a significant yet undisclosed biotransporter of Endocrine Disrupting Compounds in the marine environment. The authors determined the concentration of bisphenol A (BPA), 4-tert-octylphenol (4-t-OP) and 4-nonylphenol (4-NP) removed from birds and seals in their droppings into the coastal zone of the Gulf of Gdansk (Southern Baltic Sea).The research was carried out on samples of bird guano collected during the breeding season and after in 2016 at nesting sites, as well as on faecal samples from grey seals (Halichoerus grypus grypus) living in the Seal Centre of the Marine Station in Hel between 2014 and 2018. Measurements were carried out using high performance chromatography with fluorescence detector. Results have shown that the presence of seabird habitats and grey seal colonies in the coastal zone of the Gulf of Gdansk can have an impact on the pollution of the seashore (beach sand, bottom sediment and surface seawater) with phenol derivatives. The concentrations of BPA, 4-t-OP and 4-NP ranged from 0.1 to 32.97 ng∙g^-1dw in sediment and beach sand, and from 0.23 to over 800 ng dm^-3 in seawater. In the cases of bisphenol A and 4-tert-octylphenol safe concentration levels in the waters were exceeded. Bisphenol A concentrations were almost always found to be the highest. This was also noted in bird guano and seal faeces, although it was found to be much higher in the seal faeces - average 10149.79 ng g^-1 dw, than in bird guano. An experiment conducted to assess BPA, 4-t-OP, 4-NP leaching from bird guano and seal faeces into seawater, also confirmed the importance of animal excrement in the circulation of these compounds in the marine ecosystem. The highest % of leaching related to BPA was noted at 20 °C and reached 84%. The lowest % of leaching was for 4-nonylphenol (44%).

Meteorological phenomenon as a key factor controlling variability of labile particulate mercury in rivers and its inflow into coastal zone of the sea

Mercury (Hg) is recognized as a global pollutant, which can be transported to the sea by suspended particulate matter (SPM) via rivers constituting the main source of mercury in the southern Baltic sea. The aim of the present study was to characterize the mercury fractions in suspended particulate matter, as well as the transformations of Hg during its riverine transportation into the sea. The thermo-desorption method was used to determine the labile and stable mercury fractions in SPM of rivers (Reda, Zagórska Struga, Gizdepka, Płutnica) within the Baltic Sea basin. In this paper six "periods" were designated (heating, non-heating, drought, rains, downpour/flood and thaws), during which the river suspended particulate matter was enriched with various fractions of mercury. Meteorological and hydrological phenomena such as downpours and thaws intensified surface runoff, causing an increase in the share of Hg_abs and Hg_ads1 mercury fractions in suspended particulate matter. Whereas, droughts contributed to the formation of HgS in a large river and to an inflow of adsorbed Hg in smaller rivers decrease of air temperature leads to increase of fossil fuel combustion and then increases the share of adsorbed Hg (mainly bound with halides) in riverine particulate matter. In the non-heating season, the main fraction was the mercury absorbed inside organic matter.

Impacts of Hydrological Processes on Stream Temperature in a Cold Region Watershed Based on the SWAT Equilibrium Temperature Model

Variance in stream temperature from historical norms, which reflects the impacts from both hydrological and meteorological factors, is a significant indicator of the stream ecosystem health. Therefore, it is imperative to study the hydrological processes controlling stream temperature in the watershed. The impacts of hydrological processes on stream temperature in the cold region of Western Canada were investigated based on the previously developed Soil and Water Assessment Tool (SWAT) equilibrium temperature model. The model was calibrated and validated for streamflow and stream temperature based on the observations and a global parameter sensitivity analysis conducted to identify the most important hydrological process governing the stream temperature dynamics. The precipitation and air temperature lapse rates were found to be the most sensitive parameters controlling the stream temperature, followed by the parameters regulating the processes of soil water dynamics, surface runoff, and channel routing. Our analysis showed an inverse relationship between streamflow volume and stream temperature, and different runoff components have different impacts on temporal regimes of stream temperatures. This study elaborates on the response of the stream temperature to changes in hydrological processes at the watershed scale and indicates that hydrological processes should be taken into account for prediction of stream temperatures.

Mobility of mercury in soil and its transport into the sea

Mercury (Hg) is deposited temporarily in soil and can be remobilised into rivers and seas. Given that rivers are a significant part of the mercury budget in the southern Baltic region (inland sea located in northern Europe) and meteorological changes (e.g. intense rain, drought) are observed more frequently, it is important to recognize the factors affecting the cycling of bioavailable Hg forms. The aim of this study was to identify the processes influencing the changes of labile and stabile mercury proportion in soil and the potential impact on the outflow of labile Hg into fluvial systems. For this purpose, soil samples, river sediments, and river water were collected from the Reda River (southern Baltic Sea catchment area) during the 2015 hydrologic year. The material was analysed for total and particulate mercury content and Hg forms, by a thermo-desorption method. The analysis showed that due to changes of meteorological and hydrological conditions Hg can enter rivers and then be introduced into the marine environment in various forms. On the one hand due to high precipitation events washing out of labile (i.e. bond with halogenides, MeHg, HgSO₄), Hg forms into the river can be enhanced which affects increasing of availability of the most dangerous Hg form in the water systems. On the other hand the same event can cause the limitation of bioavailable mercury forms by a conversion of labile Hg into the most stable one (HgSO₄ ➔ HgS) under anaerobic conditions.

Forms of mercury in the Baltic mussel (Mytilus trossulus): Human and ecosystem health risk assessment

Mercury (Hg) is one of the most dangerous environmental pollutants. A significant source of this toxic element to the human body is the consumption of seafood - including the increasingly popular mussels. Mussels also play an important role in the marine ecosystem, providing a food base for fish and birds. The study aimed to determine the level of total Hg and its labile and stable forms in the Baltic mussel (Mytilus trossulus), as well as to indicate the factors that shape them. The research was conducted in the Puck Bay (Polish part of the southern Baltic Sea) in 2012-2013. The study material consisted of M. trossulus mussels, the components of their diet (suspended matter and phytoplankton), and surface sediments. Concentrations of total Hg (Hg_TOT) and the individual Hg forms were established using the thermodesorption method on a DMA-80 analyser (Milestone). The obtained results showed that the level of Hg concentration in M. trossulus from the Puck Bay was shaped by the individual features of specimens, related to the growth and reproductive cycle of mussels, as well as the quality of food consumed by them. The total share of labile Hg forms in M. trossulus was high, exceeding 90% of Hg_TOT, and the predominant form was the most dangerous organic Hg. This means that almost all of the Hg accumulated in mussels can be transferred to higher trophic levels. The obtained results showed that Baltic mussels were characterised by levels of Hg_TOT and organic Hg deemed to be safe for humans. A positive relationship was noted between the Hg_TOT concentration in a mussel's tissues and the length of its shell. Smaller sized organisms demonstrated not only by lower Hg concentrations, but also by better condition and, consequently, higher nutritional value.

Temporal changes in the content of labile and stabile mercury forms in soil and their inflow to the southern Baltic Sea

Rivers represent the main source of mercury (Hg) in the Southern Baltic. Nevertheless, the concentration and proportion of individual Hg forms in rivers depend on the management of the river basin, as well as on the intensity of meteorological phenomena. Hence the aim of the present study was to determine the influence of drought and rains/intense rains on the content of labile and stable Hg forms in the soil of river catchments with various types of land management, and on the inflow of bioavailable mercury to the coastal zone of the sea. Soil and sediment samples were taken from two rivers flowing into Puck Bay (Southern Baltic): the Reda and Gizdepka. In order to determine Hg concentration and the proportions of its particular forms in the collected material, the thermo-desorption method was used. Five periods were identified during which the soil was enriched with various Hg forms. The obtained results showed that in periods of intensive development of vegetation, the soil becomes enriched with absorbed mercury (Hg_abs). On the other hand, as a result of Hg emissions during the heating of buildings, mercury associated with halides (Hg_ads1) is deposited on land, as was primarily recorded in catchments where individual household furnaces were found. Both mild and intense rainfalls intensified the surface run-off, which contributed to soil erosion, causing the transport of both Hg_abs and Hg_ads1 to the river bed. However, the soil was more enriched with labile mercury in anthropogenic catchments, as they are only slightly overgrown with vegetation, the presence of which limits soil erosion. During periods of snow melting, there was intensive leaching and transportation of Hg_ads1, which had been deposited on the land surface during the intensive combustion of fossil fuels. In each of the designated periods, stable mercury sulphide was formed in the soil. However, the highest proportion of HgS was found during a period of drought, when organic matter decomposed and there was inflow of sulphur compounds from farms. Taking into consideration the anomalous study periods, the largest load of mercury introduced along with the bed sediment of the Gizdepka into the sea was recorded during downpour/flood. Nevertheless, the most bioavailable Hg-enriched load was introduced during snow melting period.

Changes in total mercury, methylmercury, and selenium blood levels during different life history stages of the Baltic grey seal (Halichoerus grypus grypus)

Using the blood of grey seal pups, the blood and milk of female grey seals inhabiting the Hel Marine Station of Gdansk University's Institute of Oceanography (HMS), we monitored the transfer of total mercury (THg), methylmercury (MeHg), and selenium (Se) with blood during foetal life and nursing. Changes in the concentration of mercury and selenium were characterised in the pups' blood during their first three months of life when they transition from suckling, to a post-weaning fast, to eating fish. In the blood of pregnant females, there was a significant decrease in THg and MeHg concentrations throughout the gestation, indicating the transfer of these toxins through the placenta into the foetus. At no other stage of the pup's development was there such a high level of THg and MeHg as on the day of birth, despite the incorporation of mercury into the lanugo during foetal growth. This suggests that the maternal transfer of mercury during gestation may be the time of greatest mercury exposure for a young seal pup. The consumption of milk caused a rapid increase in weight and a lowering of the mercury level in the blood in the subsequent days of the pups' life. The postweaning fast was the period of the lowest mercury concentration. The switch to a diet consisting of fish caused a systematic increase in the concentration of mercury in the blood of the pups. Milk was the significant source of selenium for pups and the selenium concentration in females' blood was reduced during lactation. The nursing period seemed to have the greatest impact on the mercury and selenium blood levels in examined seals. Natural development of the grey seal pup created an opportunity to decrease the levels of toxic substances obtained through the maternal transfer during foetal growth.

Impact of hydrotechnical works on outflow of mercury from the riparian zone to a river and input to the sea

The aim of this research was to assess the impact of hydrotechnical works within the riverbed and riparian zone on the mobility of mercury in soil and its outflow to the river and the sea. Deepening and reconstruction of the riverbed or the cutting of reeds, influenced the fate of mercury in the river system. However, only activitis that disturbed the riperian zone increased mobilization of Hg in soils. Hg transformations in these places were controled by inflow of fresh organic matter in soil and sediments as well as by oxidation-reduction potential. In areas where reducing conditions occurred, mercury released from the soil was incorporated into the sediment. However, in areas where oxidizing conditions prevailed in the sediment, mercury flowing out of the soil occurred mainly in dissolved form and most of it was transported downstream from where it could reach the sea.

The river runs through it: The Athabasca River delivers mercury to aquatic birds breeding far downstream

This study examined factors contributing to temporal variability (2009–2017) in total mercury (THg) concentrations in aquatic bird eggs collected in the Peace-Athabasca Delta and Lake Athabasca in northern Alberta. Factors examined included year of egg collection, site of collection, bird species, bird diets, annual surface-mineable oil sands production, forest fires, and flow of the Athabasca River. Surface mining activities associated with Alberta’s Athabasca oil sands are situated north of Fort McMurray, Alberta, adjacent to the northward-flowing Athabasca River. Previous studies have found that oil sands industrial operations release mercury into the local (within ~50 km) environment. An information-theoretic approach revealed that the best model for explaining egg THg levels included Athabasca River flow, bird food source, and bird species. Variability in egg THg levels was partly a reflection of differences in food sources, e.g. proportions of aquatic versus terrestrial food in bird diets. Annual fluctuations in maximal flow of the Athabasca River were also important with eggs collected following years of high maximal flow exhibiting higher THg concentrations. Furthermore, eggs collected in years of high versus low flow differed in their stable Hg isotope composition with less mass-independent fraction of ¹⁹⁹Hg and ²⁰¹Hg in years of high flow. Riverine processes associated with suspended sediment were likely critical in regulating Hg availability to nesting birds. This study highlights the importance of the Athabasca River as a conduit for Hg transport to ecologically-sensitive downstream ecosystems such as the Peace-Athabasca Delta and Wood Buffalo National Park (a UNESCO World Heritage Site). Human activities that increase atmospheric Hg deposition to the Athabasca River watershed, or that enhance Hg releases to the river through erosion of Hg-bearing soils, will likely increase the availability of Hg to organisms inhabiting downstream areas.

Legacy and emerging pollutants in the Gulf of Gdańsk (southern Baltic Sea) - loads and distribution revisited

Coastal marine areas of densely populated countries are exposed to a wide array of human activities having an impact on their ecological status. The Baltic Sea is particularly susceptible to pollution by hazardous substances (limited water exchange, shallowness, and large catchment area). Polish media regularly reports ecological catastrophes in the Gulf of Gdańsk area caused by eg. shipwrecks leaking. Thus, there is a need of a broad scientific based report on recent contaminant loads and distribution. In this review paper, we report loads of contaminants from different obvious and non-obvious sources. We also gather data on legacy and new emerging contaminant concentrations measured in the Gulf of Gdańsk within the last decade (2008-2018). The paper also includes available biological effect measurements performed recently as well as a summary of needs and gaps to be filled for the development of reliable risk assessment.

Seasonal variation in accumulation of mercury in the benthic macrofauna in a temperate coastal zone (Gulf of Gdańsk)

The main source of toxic mercury (Hg) in the human body is the consumption of fish and seafood. Therefore, it is particularly important to indicate the processes that condition Hg accumulation in marine organisms, especially those in the basal links of the food chain, which are rather poorly investigated compared to top predators. The aim of the study was to determine the seasonal variability of Hg concentrations in macrozoobenthic organisms and the factors that condition it. The research was conducted in 2012-2013 in a temperate coastal zone (Gulf of Gdańsk). The obtained results showed that both Hg concentrations within one trophic level, and their seasonal variation, may differ significantly if the organisms have different feeding habits. The research also indicated that the seasonal variability of Hg level in macrozoobenthos depended on a number of both biotic factors (primary production volume, biomass and rate of fauna metabolism) and abiotic factors (salinity and ionic composition of water, Eh). The variability of Hg concentrations in macrozoobenthos during the study period was different at the research stations, which were subjected to different land influence (e.g. surface run-off, coastal erosion), and consequently differed in the quantity and quality of organic matter. The increased load of suspended particulate matter (SPM) was also an important factor influencing the increase in Hg concentration in macrozoobenthos, regardless of their trophic status. This indicates that SPM is an important source of food for zoobenthos, even in species that prefer a different feeding strategies. The obtained results also showed the role of climate changes observed in the temperate zone - in particular, the warming of the winter season - in shaping the Hg level in macrozoobenthos. The accumulation of Hg in the bottom fauna occurred most intensively in spring immediately after a long period of icing - Hg concentrations were then much higher than those measured after a mild winter, during which the ice cover persisted for a short time. The warming of the winter season and the extension of the vegetation season contributed to an increase in macrozoobenthic biomass, and consequently to the biodilution of Hg, which could have had a negative effect on the Hg load introduced into the trophic chain.

Coastal erosion-a "new" land-based source of labile mercury to the marine environment

Mercury (Hg) can be introduced into the marine environment in many different ways. In the case of the Baltic Sea, rivers and atmospheric deposition are the predominant ones. However, in the face of ongoing climate change, a new potential source, coastal erosion, is starting to become more important and is currently considered to be the third largest source of Hg in the Gdansk Basin region. It is especially significant along sections of coastline where, due to the higher frequency of extreme natural phenomena such as storms, heavy rains, and floods, increased erosion processes have already been noted. Cliffs, which account for about 20% of the Polish coastline, are particularly vulnerable. The aim of the study was to estimate the annual load of labile Hg entering the Gdansk Basin as a result of coastal erosion. Samples of down-core sediments (0-65 cm) were collected in the years 2016-2017 from selected cliffs situated in the Gulf of Gdansk area. The thermodesorption method was used to distinguish between labile and stable fractions of Hg. Considering the mean total Hg concentrations in the collected sediments (9.7 ng g^-1) and the mean share of labile (64%), bioavailable mercury, it was estimated that the load of labile Hg originating from coastal erosion entering the Gdansk Basin is 10.0 kg per year. The load can increase by up to 50% in the case of episodic abrasion events during heavy storms and rains.

The variability of Hg concentration and composition of marine phytoplankton

Mercury is a toxic element. It undergoes biomagnification in the marine trophic chain, which is why it is significant to identify the factors influencing its bioaccumulation on the first level of the trophic chain. At present, the input of heavy metals to the southern Baltic is being reduced. On the other hand, the parameters influencing mercury remobilisation in the environment are a subject to a long-time trend associated with climate changes. Examples include growing number of heavy rain events causing surges or floods, and increased frequency of storm winds leading to increased coastal erosion as well as overall temperature increase. The present studies were carried out in the coastal zone of the Gulf of Gdańsk (southern Baltic) for 18 months at two stations (Chałupy and Osłonino) located in the Puck Lagoon, and for 12 months in Gdynia. Climate changes influence the abundance and species composition of phytoplankton, which in consequence has an effect on Hg accumulation and magnification in the trophic chain, and in the human body as a result. Extreme phenomena such as land erosion or floods resulted in an additional inflow of nutrients, but also toxic substances, into the coastal zone. The bioconcentration factor (BCF) increased almost four times after abrasion of cliff. That was conducive to the growth of microflora, as well as increased Hg accumulation. The highest bioconcentration of Hg in phytoplankton was observed when the Mesodinium rubrum (spring and autumn) and Diatomophyceae (winter) prevailed in biomass. The BCF was then almost tenfold higher than during the rest of the year.

The effect of land use in the catchment and meteorological conditions on the riverine transport of dissolved organic carbon into the Puck Lagoon (southern Baltic)

Dissolved organic carbon (DOC) concentration and fluxes from four rivers draining the catchment of the Puck Lagoon in southern Baltic are presented. Water samples from rivers and coastal zone close to the rivers' mouth were collected from April 2015 to March 2017. DOC was measured using high temperature catalytic oxidation with an NDIR detection. DOC concentration in rivers as well as area specific load discharged to the lagoon reflected variations of land use along their course. Area specific load of DOC discharged by rivers with high proportion of forests, meadows, and pastures in the catchment was significantly higher as compared to rivers with catchment dominated by arable land. However, the main controlling factor of the total discharged loads of DOC was the water flow. The highest loads were observed during the downpour. That was due to the larger volumes of water transported with rivers and the higher concentration of DOC resulting from increased leaching from the catchment area. The obtained results are especially important in the light of climate change in the southern Baltic region. According to the forecasts, we can expect increased precipitation and flooding and consequently increased leaching from the catchment and transport of DOC to the sea via rivers.

Watershed characteristics and climate factors effect on the temporal variability of mercury in the southern Baltic Sea rivers

Mercury (Hg) is a neurotoxic metal which can enter into the human organism mainly by fish consumption, skin and transpiration. In the coastal zone of the southern Baltic Sea, rivers are the main source of Hg. The Polish region represents the largest proportion of the Baltic Sea catchment and this research included four rivers of the Baltic watershed: the Reda, Zagórska Struga, Kacza and Gizdepka. The samples were collected in the years 2011-2013. Total and particulate Hg concentration in these rivers were measured. Due to intensive rain, deposited mercury on the catchment area was washed out into the riverines water and introduced into the Baltic Sea. Consequently, the load of Hg increased three times. Additionally, the intensive dry atmospheric deposition during heating season caused the increase of the concentration of particulate Hg in the river water even by 85%. The research confirmed the role of the river flow magnitude in the load of mercury introduced into the sea by rivers. Moreover, a high variability of mercury concentration was connected to the additional sources such as the chemicals containing Hg and no municipal sewage system. The analysis of stable isotopes indicated that the SPM contained terrestrial organic matter; however, there was no clear correlation between Hg_tot, C_org and N_tot concentrations and δ¹³C, δ¹⁵N, C/N in particulate matter.

Impact of intense rains and flooding on mercury riverine input to the coastal zone

The aim of the present research was to determine the impact of intense rains and flooding on mercury riverine input to the coastal zone. This study focused on four small rivers (Reda, Zagórska Struga, Płutnica, Gizdepka), typical of the Southern Baltic region, with no significant mercury sources. Samples were collected for 16months during average flow conditions and during selected meteorological events: floods, downpours, thaws and droughts. Results showed decreased retention of mercury during intense rainfalls, thus demonstrating mercury elution from the catchment. Floods and melting snow also have a tremendous impact on the outflow of mercury from the catchment. Development of urban infrastructure and farmlands increases the outflow of mercury from the catchment too, making such areas a significant source of mercury in the river. On the other hand, areas with natural character, predominated by forests, stimulate retention of mercury that reaches them through dry and wet atmospheric deposition.

Mercury in the Diatoms of Various Ecological Formations

Mercury is a neurotoxin, its main source in the human organism being fish and seafood. The first level in the marine food web is formed of planktonic and benthic photosynthetic microorganisms, which form a biofilm on the surface of the hard bottom (epilithon) or plants (epiphyton). They are carriers of nutritional as well as toxic substances and pass these on to subsequent levels of the trophic web. Their biomass is often dominated by diatoms. This was the basis for the presented study into Hg accumulation in epilithic, epiphytic and planktonic diatoms, which was carried out in 2012-2013 in the coastal zone of the Puck Lagoon and the Gulf of Gdańsk (southern Baltic). In this coastal area, both micro- and macroorganisms develop particularly intensively. The collected results indicate an increase in Hg concentration in the biofilm during the warm season which, with the lengthening of the vegetative period due to global warming in recent years, is of great significance. As a consequence, the annual mercury load entering the trophic web is larger in comparison with a year in which there is a long, cold winter. An important parameter influencing the accumulation of Hg was the function of those organisms from the biofilm-forming communities. In this case, the highest concentrations of Hg were measured in organisms forming high-profile guilds.

Long-term variation in concentrations and mass loads in a semi-arid watershed influenced by historic mercury mining and urban pollutant sources

Urban watersheds are significantly anthropogenically-altered landscapes. Most previous studies cover relatively short periods, without addressing concentrations, loads, and yields in relation to annual climate fluctuations, and datasets on Ag, Se, PBDEs, and PCDD/Fs are rare. Intensive storm-focused sampling and continuous turbidity monitoring were employed to quantify pollution at two locations in the Guadalupe River (California, USA). At a downstream location, we determined loads of suspended sediment (SS) for 14yrs., mercury (HgT), PCBs, and total organic carbon (TOC) (8yrs), total methylmercury (MeHgT) (6yrs), nutrients, and trace elements including Ag and Se (3yrs), DDTs, chlordanes, dieldrin, and PBDEs (2yrs), and PCDD/Fs (1yr). At an upstream location, we determined loads of SS for 4yrs. and HgT, MeHgT, PCBs and PCDD/Fs for 1yr. These data were compared to previous studies, climatically adjusted, and used to critically assess the use of small datasets for estimating annual average conditions. Concentrations and yields in the Guadalupe River appear to be atypical for total phosphorus, DDTs, dieldrin, HgT, MeHgT, Cr, Ni, and possibly Se due to local conditions. Other pollutants appear to be similar to other urban systems. On average, wet season flow varied by 6.5-fold and flow-weighted mean (FWM) concentrations varied 4.4-fold, with an average 7.1-fold difference between minimum and maximum annual loads. Loads for an average runoff year for each pollutant were usually less than the best estimate of long-term average. The arithmetic average of multiple years of load data or a FWM concentration combined with mean annual flow was also usually below the best estimate of long-term average load. Mean annual loads using sampled years were also less than the best estimate of long-term average by a mean of 2.2-fold. Climatic adjustment techniques are needed for computing estimates of long-term average annual loads.

Transfer of mercury and phenol derivatives across the placenta of Baltic grey seals (Halichoerus grypus grypus)

The placenta is an intermediary organ between the female and the developing foetus. Some chemical substances, including the most harmful ones, exhibit the ability to accumulate in or penetrate through the placenta. The aim of the study was to determine the role of the placenta of the Baltic grey seal (Halichoerus grypus grypus) in the transfer of endocrine disrupting compounds (EDCs) - (bisphenol A, 4-tert- octylphenol, 4- nonylphenol), as well as total and organic mercury. 30 placentas were collected from grey seals pupping under human care at the Hel Marine Station in the years 2007-2016. The assays were conducted using the technique of high-preformance liquid chromatography (phenol derivatives) and atomic absorption spectrometry (mercury and selenium). A measurable level of EDCs was indicated in the placentas of grey seals. It was established that the inorganic Hg form was accumulated in the placenta, and that its concentrations were an order of magnitude higher than the concentrations of the organic form, which penetrated to the foetus. Similar observations were made for phenol derivatives - bisphenol A, 4-tert- octylphenol and 4-nonylphenol. For this compound group the placenta was a barrier, but the properties of phenol derivatives suggest the possibility of their penetration through this organ.

Mercury in suspended matter of the Gulf of Gdańsk: Origin, distribution and transport at the land-sea interface

The coastal regions of inland seas are particularly vulnerable to Hg pollution. An important carrier of toxic Hg in the marine environment is suspended matter originating from multiple sources. The present study was conducted in the Gulf of Gdańsk and its adjoining land in the years 2011-2013. The results indicated that the Hg_SPM (Hg bound with suspended particulate matter) concentrations varied horizontally and vertically and were dependent on the water dynamics and the composition of organic matter. Conditions favourable for the accumulation of matter and adsorption of reactive gaseous mercury led to increasing Hg_SPM levels, which are especially hazardous in the case of semi-enclosed areas such as estuaries. These conditions also increase the Hg loads into the trophic chain through suspension feeders. Moreover, the Hg_SPM concentration was significantly affected by seasonal phenomena (mainly coastal erosion) and the quantity and quality of primary production (phytoplankton blooms, mainly Mesodinium rubrum).

Eutrophication Increases Phytoplankton Methylmercury Concentrations in a Coastal Sea-A Baltic Sea Case Study

Eutrophication is expanding worldwide, but its implication for production and bioaccumulation of neurotoxic monomethylmercury (MeHg) is unknown. We developed a mercury (Hg) biogeochemical model for the Baltic Sea and used it to investigate the impact of eutrophication on phytoplankton MeHg concentrations. For model evaluation, we measured total methylated Hg (MeHg_T) in the Baltic Sea and found low concentrations (39 ± 16 fM) above the halocline and high concentrations in anoxic waters (1249 ± 369 fM). To close the Baltic Sea MeHg_T budget, we inferred an average normoxic water column Hg^II methylation rate constant of 2 × 10^-4 d^-1. We used the model to compare Baltic Sea's present-day (2005-2014) eutrophic state to an oligo/mesotrophic scenario. Eutrophication increases primary production and export of organic matter and associated Hg to the sediment effectively removing Hg from the active biogeochemical cycle; this results in a 27% lower present-day water column Hg reservoir. However, increase in organic matter production and remineralization stimulates microbial Hg methylation resulting in a seasonal increase in both water and phytoplankton MeHg reservoirs above the halocline. Previous studies of systems dominated by external MeHg sources or benthic production found eutrophication to decrease MeHg levels in plankton. This Baltic Sea study shows that in systems with MeHg production in the normoxic water column eutrophication can increase phytoplankton MeHg content.

Coastal erosion as a source of mercury into the marine environment along the Polish Baltic shore

The climate changes in recent years in the southern Baltic have been resulting in an increased frequency of natural extreme phenomena (i.e. storms, floods) and intensification of abrasion processes, which leads to introduction of large amounts of sedimentary deposits into the marine environment. The aim of this study was to determine the mercury load introduced to the Baltic Sea with deposits crumbling off the cliffs-parts of the coast that are the most exposed to abrasion. The studies were carried out close to five cliffs located on the Polish coast in the years 2011-2014. The results show that coastal erosion could be an important Hg source into the marine environment. This process is the third most important route, after riverine and precipitation input, by which Hg may enter the Gulf of Gdańsk. In the Hg budget in the gulf, the load caused by erosion (14.3 kg a(-1)) accounted for 80 % of the wet deposition and was 50 % higher than the amount of mercury introduced with dry deposition. Although the Hg concentration in the cliff deposits was similar to the natural background, due to their large mass, this problem could be significant. In addition, the preliminary studies on the impact of coastal erosion on the Hg level in the marine ecosystem have shown that this process may be one of the Hg sources into the trophic chain.

Methylation index as means of quantification of the compliance of sedimentary mercury to be methylated

Methylmercury (MeHg) is the most bioavailable and toxic mercury species in the marine environment. MeHg concentration levels, methylation rates leading to MeHg formation, and methylation index (MI) are all used to assess the compliance of mercury to be methylated in the marine sedimentary environment. This paper reports on the works conducted on the MI upgrade. This paper proposes a new formula for calculating MI. Apart from labile mercury(II) and organic matter, it includes redox potential and abundance of sulfur-reducing bacteria (SRB), both essential factors for MeHg generation. The obtained MI is validated against actual sedimentary MeHg concentrations proving the potential usefulness of MI as a factor characterizing status of sedimentary environment regarding possible occurrence of MeHg. Moreover, values of the methylation index in particular regions show that MI values correspond well to environmental conditions in those areas. The values calculated correlate well with MeHg concentrations; however, the correlation coefficients vary between different regions. This has been attributed to the lack of empirical coefficients. Thus, MI could be used as a characteristic of the sedimentary environment indicating the potential presence of MeHg. It could also be used in methylation rate modeling, provided that empirical constants are applied to improve model performance.

Mercury in the eggs of aquatic birds from the Gulf of Gdansk and Wloclawek Dam (Poland)

The aim of this paper was to assess the influence of diet on the concentrations of total mercury (HgTOT) in the eggs of aquatic birds. Trophic level was determined using stable isotopes (δ(15)N, δ(13)C). Analysis was carried out on eggs (laid in 2010-2012) belonging to two species of terns nesting at the River Vistula outlet on the Gulf of Gdansk and on herring gulls nesting both in Gdynia harbour and on the Vistula dam in Wloclawek. The results show that seafood diet causes the highest load of mercury, that which is transferred into terns eggs. The amounts of accumulated mercury obtained were found to be different in the particular egg components with Hgalbumen > Hgyolk > Hgmembrane > Hgshell. In the herring gull eggs, three stages of embryo development with varying levels of mercury were determined. It was observed that mercury received from the albumen and yolk was most effectively removed when developing embryo into down.

Macrophyta as a vector of contemporary and historical mercury from the marine environment to the trophic web

Macrophyta are the initial link introducing toxic mercury to the trophic chain. Research was carried out at 24 stations located within the Polish coastal zone of the Southern Baltic, in the years 2006-2012. Fifteen taxa were collected, belonging to four phyla: green algae (Chlorophyta), brown algae (Phaeophyta), red algae (Rhodophyta) and flowering vascular plants (Angiospermophyta), and total mercury concentrations were ascertained. The urbanisation of the coastal zone has influenced the rise in Hg concentrations in macroalgae, and the inflow of contaminants from the river drainage area has contributed to an increase in metal concentration in vascular plants. At the outlets of rivers possessing the largest drainage areas in the Baltic (the Vistula and the Oder), no increases in mercury concentration were observed in macrophyta. Increase in environmental quality and a prolonged vegetative season results in the growing coverage of algae on the seabed and in consequence leads to rapid introduction of contemporary mercury and Hg deposited to sediments over the past decades into the trophic chain. Thriving phytobenthos was found to affect faster integration of Hg into the trophic web.

The Influence of Weather Anomalies on Mercury Cycling in the Marine Coastal Zone of the Southern Baltic-Future Perspective

Despite the decreased emission loads of mercury, historical deposits of this metal in various compartments of the environment may become an additional diffuse source in the future. Global climate change manifests itself in the temperate zone in several ways: warmer winters, shorter icing periods, increased precipitation and heightened frequency of extreme events such as strong gales and floods, all of which cause disturbances in the rate and direction of mercury biogeochemical cycling. The present study was conducted at two sites, Oslonino and Gdynia Orlowo (both in the coastal zone of the Gulf of Gdansk), from which samples were collected once a month between January 2012 and December 2012. In the Southern Baltic region, climate changes can certainly enhance coast to basin fluxes of mercury and the transfer of bioavailable forms of this metal to the food web. They may also, in the future, contribute to uncontrollable increases of mercury in the seawater.

Chlorinated herbicides in fish, birds and mammals in the Baltic Sea

The aim of the present work was to determine the concentration levels, as well as accumulation and magnification coefficients, of triazine derivatives in herring gulls and Baltic grey seals 11 years after a ban on their use in the EU and eight after their exclusion in Poland. Dead birds were collected in the coastal zone of the Gulf of Gdansk in the years 2010-2012. The grey seals, on the other hand, were from before 2007, when s-triazine derivatives were still in use. Triazine herbicides (atrazine, simazine, propazine, terbutrine, prometrone, prometrine and ametrine) were found in the muscles and livers of birds and mammals and also in fish. The obtained results indicated the presence of all the assayed triazines in whole Baltic herring and their livers, while fish muscles were found to be free of prometrone and ametrine. In the muscles and liver of the grey seal, no ametrine, propazine or terbutrine were found, while prometrine was found in the liver of only one specimen. Research showed that simazine did not accumulate and magnify in marine birds and mammals. Atrazine became accumulated in the liver of birds and mammals while magnification was determined in their muscles. The accumulation of ametrine was found in the muscles of seals.

Total, methyl and organic mercury in sediments of the Southern Baltic Sea

Distribution of sedimentary mercury in the Southern Baltic was investigated. Sediment samples were collected from the Southern Baltic in the period from 2009 to 2011, and concentrations of sedimentary total mercury (average 102 ng/g, range 5.8-225 ng/g) and methyl mercury (average 261 pg/g, range 61-940 pg/g) were measured in the manner that the influence of both patchiness and seasonal changes were assessed. Moreover, sedimentary mercury extracted with organic solvent- the so-called organic mercury was also analyzed (average 425 pg/g, range 100-1440 pg/g). There is a statistically significant dependence between organic mercury and both methyl mercury and total mercury concentrations in the sediments. Methyl mercury contribution to total mercury varied from 0.12% to 1.05%, while organic mercury contributed to 2% of total concentration on average. The area studied, although mercury concentrations exceed threefold the geochemical background, can be regarded as moderately contaminated with mercury, and methylmercury.

Factors influencing variability of mercury input to the southern Baltic Sea

The southern Baltic countries have been identified as significant sources of Hg into the sea. Are anthropogenic activities the sole source? How do meteorological parameters influence the deposition? Studies on input of Hg to the Baltic were conducted in 2008-2012 in the Polish coastal stations. The riverine load was found to depend directly or indirectly on the amount of precipitation and catchment type. Input of atmospheric Hg increased along with the number of precipitation episodes from remote maritime air masses, as well as with the number of days when continental air masses from regional (when domestic heating prevailed) and remote sources moved over the Baltic, during the heating season. During the non-heating season metal input was found to be proportional to episodes of rain from continental regional air masses and to the number of days under influence of continental and maritime air masses from regional sources.