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.

Biogeochemical control of the coupled CO2-O 2 system of the Baltic Sea: a review of the results of Baltic-C.

Past, present, and possible future changes in the Baltic Sea acid-base and oxygen balances were studied using different numerical experiments and a catchment-sea model system in several scenarios including business as usual, medium scenario, and the Baltic Sea Action Plan. New CO2 partial pressure data provided guidance for improving the marine biogeochemical model. Continuous CO2 and nutrient measurements with high temporal resolution helped disentangle the biogeochemical processes. These data and modeling indicate that traditional understandings of the nutrient availability-organic matter production relationship do not necessarily apply to the Baltic Sea. Modeling indicates that increased nutrient loads will not inhibit future Baltic Sea acidification; instead, increased mineralization and biological production will amplify the seasonal surface pH cycle. The direction and magnitude of future pH changes are mainly controlled by atmospheric CO2 concentration. Apart from decreasing pH, we project a decreasing calcium carbonate saturation state and increasing hypoxic area.

Uptake, accumulation, and translocation of Zn, Cu, Pb, Cd, Ni, and Cr by P. australis seedlings in an urban dredged sediment mesocosm: Impact of seedling origin and initial trace metal content.

The study presents results from 6 months of phytoremediation of sediments dredged from three urban retention tanks carried out in a mesocosm setup with the use of P. australis. Two kinds of P. australis seedlings were considered: seedlings originating from natural (uncontaminated - Suncont) and anthropogenically changed environments (contaminated - Scont); this distinction was reflected in the baseline concentrations of trace metals inside their tissues. The potentially toxic elements (PTEs) considered in this study were as follows: Zn, Cu, Cd, Ni, Cr, and Pb. The aim of the study was to compare the uptake, accumulation, and translocation properties of seedlings with different initial trace metal contents. The PTE concentrations were analyzed in sediments as well as in belowground and aboveground parts of plants in the middle (3rd month) and at the end of the investigation period using inductively coupled plasma mass spectrometry (ICP-MS), and the accumulation of PTEs in plant tissues was calculated. Phytoextraction efficiency was evaluated using the bioconcentration factor (BF) and translocation factor (TF). Plant morphology was assessed with scanning electron microscopy (SEM) to document plant stress due to PTE exposure. The results of our study indicated that P. australis seedlings originating from sites differing in the initial trace metal content exhibited different behavior when grown on sediments dredged from urban retention tanks. Suncont seedlings with low initial metal contents tended to adapt to the dredged sediments and showed phytoextraction ability, while Scont seedlings originating from sites with initial high contents of trace metals acted as phytoexcluders and tended to release PTEs from their tissues into the sediments. The morphological and structural effects caused by metal toxicity were observed in growth limitation, root tissue disturbance, root hair number decrease, and structural alterations in the epidermis and endodermis. Therefore, the Suncont seedlings presented better properties and adaptability for phytoremediation purposes.

Identifying recent sources and fate of sedimentary nitrogen in the Baltic Sea based on organic matter elemental composition and nitrogen and carbon stable isotopes ratios.

Sedimentary nitrogen (SN) provenience and fate in surface and subsurface sediments collected from the Baltic Sea were assessed. SN and sedimentary organic carbon (SOC) concentrations, stable isotopic signatures (δ15NSN and δ13CSOC) and SOC/SN molar ratios, were determined in subsequent layers of twenty-four sediment cores dated with 210Pb/137Cs and fifty-seven surface sediments. Sedimentation rates in the range 66-736 g/m2yr-1 (0.05-0.34 cm/year) were measured. Prolonged incubation of sediments in the laboratory led to a 17-37% decrease of SN in surface sediments, and no SN loss in sediments deposited before 1940. Decrease of δ15NSN on incubation (1‰ on average), and gradients of δ15NSN, between recent - surface (3.5‰) vs. 100 years old - subsurface (2.1‰) sediments were attributed to varying contributions of labile nitrogen to the SN pool. Annual deposition of SN to sediment surface and burial in subsurface sediments amounted, respectively, to 5 ± 2 g/m2 and 3.5 ± 1 g/m2.

Sea-dumped ammunition as a possible source of mercury to the Baltic Sea sediments.

After World War II, as a move toward Germany demilitarization, up to 385,000 t of munitions were sunk in the Baltic Sea. Munition containing various harmful substances, including chemical warfare agents (CWA) and explosives, that can affect marine biota were dumped on the seafloor. Some of those objects contained mercury, either as elemental mercury or mercury compounds (e.g., mercury fulminate, a common explosive primer), and thus could act as a specific local source of mercury in the dumping areas. Unfortunately, there is a lack of information on how dumped munitions impact the mercury concentrations in the Baltic Sea sediments. This report aims to answer the question how much sedimentary mercury in the dumping areas originates from munitions and to determine to what extent the mercury present in those areas originates from mercury fulminate. Concentrations of total sedimentary mercury- HgTOT in samples collected from conventional (Kolberger Heide) and chemical (Bornholm Deep) munitions dumping sites are characterized by high variability. However, an increase in HgTOT concentrations was observed with a decreasing distance to particular munition objects at both study sites. Moreover, mercury speciation in sediments from Kolberger Heide proves that the mercury there can be traced back directly to mercury fulminate. Results of our study confirm that munitions dumpsites are a local point sources of mercury. Due to the ecosystem constrains, varying transport modes and pathways, and both unknown and varying decomposition rates, these sea-bed mercury concentrations are hard to evaluate quantitatively. Therefore we recommend that further detailed studies should be conducted to assess sedimentary mercury provenience in munitions dumpsites more accurately.

Temporal and spatial variations of selected biomarker activities in flounder (Platichthys flesus) collected in the Baltic proper.

The aim of the study was to examine temporal (monthly) and spatial changes in the activities of a battery of biomarkers and evaluate the influence of gender and environmental factors on those activities. Abiotic factors not correlated with chemical pollution-water temperature, salinity, and oxygen concentration-were evaluated. The activities of the following biomarkers-muscular ChEs (acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)), hepatic ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and catalase (CAT), and gross indices-condition factor (CF), hepatosomatic index (HSI), and gonadosomatic index (GSI)-were measured in individual flounder Platichthys flesus. Female flounder were collected once a month from April 2003 to April 2004 at Sobieszewo (Gulf of Gdansk). In December 2003 flounder of both sexes from nine stations in the Baltic Proper were caught and tested. Strong monthly (attributed mainly to spawning, and less-to pollution) and geographical (attributed to pollution) variations in biomarker activities, as well as gender differences, were demonstrated. Correlations between the enzymes with the abiotic properties of the environment were less important.

Responses of the toxic cyanobacterium Microcystis aeruginosa to iron and humic substances.

Iron is an essential element to marine biota. Different types of dissolved organic matter (DOM), such as humic substances have impacts on the marine coastal waters iron chemistry. The aim of the study was to examine how the presence of humic substances (both aquatic and sedimentary) may affect iron bioavailability to the bloom-forming cyanobacterium Microcystis aeruginosa Kutzing incubated on standard and modified mineral BG-11 media. The final iron concentrations in the growth media ranged from 0.1 to 100microM. The results demonstrate that both the growth rate and the concentration of chlorophyll a in cultures of M. aeruginosa are limited by insufficient (<10microM) Fe concentrations. The addition of aquatic humic substances in the presence of iron in concentrations <0.1microM increased the optical density 25-fold, and the production of chlorophyll a 15-fold as compared with the cultures exposed to iron only at the same concentration. Sedimentary humic acids in the presence of iron at a concentration of 10microM reduced the growth and production of chlorophyll a by 50% as compared to the cultures exposed to iron only at the same concentration. Possible mechanisms of humic substances - metal ion - alga interactions are discussed. It is suggested that aquatic humic substances could be of great importance in the formation of cyanobacteria blooms.

Intercomparison of alpha and gamma spectrometry techniques used in (210)Pb geochronology.

(210)Pb geochronology is a widely used tool in sedimentological studies aimed at the absolute ages of modern sediments (up to 100 years). (210)Pb activities required to model sedimentation regimes are measured using either alpha, gamma or beta spectrometry. Sediment accumulation rates derived from (210)Pb activity profiles measured by these methods are often used interchangeably in mass balance studies. Yet there is a lack of investigations considering the comparability of data derived using different analytical methods. Differences between methods could be caused by different behaviors of (210)Pb and (210)Po (used for alpha measurement) in the marine environment. In gamma spectrometry errors may arise when many gamma emitters are measured simultaneously and their activity peaks overlap. In alpha spectrometry chemical separation of (210)Po may result in analytical error due to incomplete sample dissolution. In the present study we evaluate total, supported and excess (210)Pb activities and their use in deriving sediment accumulation rates and (210)Pb excess inventories for three sediment cores collected from the Barents Sea. (210)Pb activities derived by alpha and gamma methods are shown to agree within counting error and there is also good agreement in the derived sediment accumulation rates. The inherent compatibility of analytical results based on alpha or gamma techniques is established.

Measurements of biomarker levels in flounder (Platichthys flesus) and blue mussel (Mytilus trossulus) from the Gulf of Gdansk (southern Baltic).

In the framework of the EU funded BEEP project a set of biomarkers, gross morphometric indices and tissue concentrations of selected organic pollutants were measured in flounder (Platichthys flesus) and mussels (Mytilus trossulus) collected twice a year (April and October) from three sites in the inner Gulf of Gdansk between autumn 2001 and spring 2003. In flounder, seasonal differences in most biomarkers were observed, but no correlations with tissue pollutant levels could be found. In mussels, highly variable levels in biomarker responses were seen, but no clear seasonal or spatial trends, directly related to tissue concentrations, could be established. The observed biomarkers distribution the study sites are probably mostly caused by interannual, seasonal and individual variability and, in case of flounder, possibly by exchange of stocks between the sampling sites.

The BEEP project in the Baltic Sea: overview of results and outline for a regional biological effects monitoring strategy.

Field studies in the framework of the EU funded BEEP project (Biological Effects of Environmental Pollution in Marine Coastal Ecosystems, 2001-2004) aimed at validating and intercalibrating a battery of biomarkers of contaminant exposure and effects in selected indicator species in the Mediterranean, the North Atlantic and the Baltic Seas. Major strategic goals of the BEEP project were the development of a sensitive and cost-efficient biological effects monitoring approach, delivery of information and advice to end-user groups, and the implementation of a network of biomarker researchers around Europe. Based on the main results obtained in the Baltic Sea component of the BEEP the present paper summarises and assesses the applicability of biomarkers for different regions and species in this sea area. Moreover, a general strategy and some practical considerations for the monitoring of biological effects in the Baltic Sea are outlined.

Use of biliary PAH metabolites as a biomarker of pollution in fish from the Baltic Sea.

During field campaigns of the BEEP project (Biological Effects of Environmental Pollution in Marine Coastal Ecosystems) in 2001-2002, metabolites of polycyclic aromatic hydrocarbons (PAHs) were determined in bile samples from three fish species, flounder (Platichthys flesus), perch (Perca fluviatilis) and eelpout (Zoarces viviparus), from four separate areas in the Baltic Sea. Two determination methods were applied: fixed wavelength fluorescence (FF) for pyrene-type metabolites and high-performance liquid chromatography with fluorescence detection (HPLC). There was a good correlation between the FF method and 1-OH pyrene determined by HPLC. Normalisation of the FF data for absorbance at 380 nm or bile protein concentrations greatly increased variance in one third and decreased it in two thirds of the cases and resulted in a loss of significant differences (protein normalisation) between the sampling stations, but normalisation of the HPLC data had little effect on the results. The biliary PAH metabolite content was usually higher in males than in females. In perch and eelpout the biliary PAH contents were at similar levels, whereas in flounder the levels were lower. The sampling areas arranged in decreasing order of biliary PAH contents were: Wismar Bay > Gulf of Gdansk > Lithuanian coast > Kvadofjärden (reference area). It is concluded that FF with un-normalised data is a reliable and simple method for monitoring purposes and only one sex of a selected species should be used.

Biomarker responses in flounder (Platichthys flesus) and mussel (Mytilus edulis) in the Klaipeda-Butinge area (Baltic Sea).

During the EU project BEEP a battery of biomarkers was applied in flounder (Platichthys flesus) and the blue mussel (Mytilus edulis) collected at three locations off the Lithuanian coast (Baltic Sea) in June and September 2001 and 2002. The elevated biomarker responses in specimens sampled in September 2001 were apparently related to the extensive dredging activities in the Klaipeda port area and subsequent dumping of contaminated sediments. High concentrations of organic pollutants (organochlorines and PBDEs) were also measured in the tissues of both indicator species. In addition, response levels of genotoxicity, cytotoxicity, immunotoxicity as well as concentrations of PAH metabolites in the bile of flounder showed elevations in 2002 after an oil spill in the Butinge oil terminal in November 2001. In flounder, biomarker measurements 10 months after the spill indicated recovery processes but in mussels a high level of genotoxicity could still be observed 22 months later. The present study illustrates the usefulness of the multi-biomarker approach in the detection of biological effects of pollution in this region of the Baltic Sea.

Significance of groundwater discharge along the coast of Poland as a source of dissolved metals to the southern Baltic Sea.

Fluxes of dissolved trace metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) via groundwater discharge along the southern Baltic Sea have been assessed for the first time. Dissolved metal concentrations in groundwater samples were less variable than in seawater and were generally one or two orders of magnitude higher: Cd (2.1-2.8nmolL(-1)), Co (8.70-8.76nmolL(-1)), Cr (18.1-18.5nmolL(-1)), Mn (2.4-2.8µmolL(-1)), Pb (1.2-1.5nmolL(-1)), Zn (33.1-34.0nmolL(-1)). Concentrations of Cu (0.5-0.8nmolL(-1)) and Ni (4.9-5.8nmolL(-1)) were, respectively, 32 and 4 times lower, than in seawater. Groundwater-derived trace metal fluxes constitute 93% for Cd, 80% for Co, 91% for Cr, 6% for Cu, 66% for Mn, 4% for Ni, 70% for Pb and 93% for Zn of the total freshwater trace metal flux to the Bay of Puck. Groundwater-seawater mixing, redox conditions and Mn-cycling are the main processes responsible for trace metal distribution in groundwater discharge sites.

Long-term changes in sewage sludge stored in a reed bed.

The problem of the utilization and management of sewage sludge originating from small wastewater treatment plants is still unsolved. A common approach is to store the sludge in plots which in time turn into grassland. This investigation was aimed at evaluating the influence of the storage time in plots on the chemical properties of sewage sludge deposited there. Tests were carried out on samples obtained from discrete layers of stratified sludge that had lain in a hydrophyte facility disused for 7 years after 23 years of continuous sludge discharge. The age of the sludge was established by the lead-210 method. Moisture, organic matter, total nitrogen and total phosphorus contents were measured in samples of dated sewage sludge. The composition of the stored biosolids stabilized with respect to phosphorus, nitrogen and organic matter within 11, 15 and 17 years, respectively.

Horizontal and vertical variabilities of mercury concentration and speciation in sediments of the Gdansk Basin, Southern Baltic Sea.

The mercury compounds introduced to the environment because of anthropogenic activity are accumulated, mainly, in marine sediments. Both distribution of mercury in the Baltic Sea and factors affecting it are remain largely unknown. Due to its complex chemistry and variable conditions in the Baltic Sea bottom sediments, mercury may be reemitted to the overlaying water, and thus to the environment. The aim of this study was twofold. Total mercury contents were measured in sediments of the Gdansk Basin along a Vistula mouth (main source)--Gdansk Deep (deposition area) transect in order to assess spatial distribution of the element. Soft and sandy bottom sediment cores were collected and cut into slices. The mercury measurements consisted of acid digestion followed by CV-AAS determination. A five-step sequential extraction procedure involving measurements of mercury species water soluble, bound to humic substances and insoluble, was employed in order to investigate mercury speciation. On the basis of speciation results stability and remobilisation potential was assessed. The second aim was demonstrating that mercury gradients in vertical profiles of the investigated sediment cores exist. Total mercury contents varied in range from 28 ng/g x dw to 844 ng/g. Mercury associated with organic matter and sulphides, (respectively 39% and 49%) were the dominant species of the element. The results indicated that the river run-off is a source of mercury in the area. Vertical gradients of both total content and speciation of mercury in the soft sediments were attributed to both remobilisation from sediments, and decreasing trend in the anthropogenic load of the element deposited to sediments.

Assessment of organotin pollution along the Polish coast (Baltic Sea) by using mussels and fish as sentinel organisms.

Levels of tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), as well as triphenyltin (TPT), were monitored in 10 stations along the Polish coast (Baltic Sea). Mussel-Mytilus edulis-and fish-Platichthys flesus-were used as sentinel organisms. The bioaccumulation patterns of butyltin and phenyltin compounds varied substantially. Butyltins were detected in mussel tissue from all the sampled stations. Among them, organisms from the Gulf of Gdansk showed the highest residues (68 ng/g w.w. as Sn) in conjunction with elevated TBT/DBT ratios, which suggest recent inputs of TBT in the area. Additionally, flatfish were sampled in the Gulf of Gdansk, and different tissues (liver, digestive tube and gills) were analyzed separately. TPT, although undetected in mussels, was always present in fish. The highest organotin concentration was observed in the liver (369 ng/g w.w. as Sn) of fish caught near Gdansk port. Relatively high concentrations were observed in digestive tube, which points out the ingestion of organotin contaminated food as an important uptake route of those compounds in P. flesus.

Caesium-137 distribution, inventories and accumulation history in the Baltic Sea sediments.

The Baltic Sea is susceptible to pollution by hazardous substances due to limited water exchange, shallowness, and the large catchment area. Radionuclides, particularly (137)Cs, are one of the most hazardous anthropogenic substances present in the Baltic environment. This study was conducted to present (137)Cs present contamination that should further be a subject of reliable monitoring when the new Nuclear Power Plant is put into operation in the northern Poland. The sea-wide, up to date distribution of (137)Cs activities and inventories in the Baltic Sea bottom sediments are presented. The (137)Cs activity concentrations were measured in 30 cm long sediment cores collected at 22 sampling stations. Sediment accumulation rates were quantified by (210)Pb geochronology to follow the history of (137)Cs accumulation. The (137)Cs inventories and fluxes were calculated. Most of the Baltic Sea sediments accumulated (137)Cs in the range from 750 to 2675 Bq m(-2). The Bothnian Bay is severely contaminated by (137)Cs with inventories up to 95,191 Bq m(-2). This region is moreover characterized by extremely large patchiness of (137)Cs inventories. The (137)Cs annual fluxes are highest at the two stations located at the Bothnian Bay (342 Bq m(-2) and 527 Bq m(-2)) due to large Chernobyl (137)Cs contamination of that region and high sediment accumulation rates. When these stations are excluded, the recent, annual mean value of (137)Cs load to the Baltic Sea deposits is 38 ± 22 Bq m(-2). The distribution of radio-caesium inventories over the Baltic Sea nowadays reflects the pattern of Chernobyl contamination. The radio-caesium deposited in surface sediments is not permanently buried, but may be resuspended and redeposited by currents, bioturbation or anthropogenic activities.

Submarine Groundwater Discharge as a Source of Mercury in the Bay of Puck, the Southern Baltic Sea.

Both groundwater flow and mercury concentrations in pore water and seawater were quantified in the groundwater seeping site of the Bay of Puck, southern Baltic Sea. Total dissolved mercury (HgTD) in pore water ranged from 0.51 to 4.90 ng l-1. Seawater samples were characterized by elevated HgTD concentrations, ranging from 4.41 to 6.37 ng l-1, while HgTD concentrations in groundwater samples ranged from 0.51 to 1.15 ng l-1. High HgTD concentrations in pore water of the uppermost sediment layers were attributed to seawater intrusion into the sediment. The relationship between HgTD concentrations and salinity of pore water was non-conservative, indicating removal of dissolved mercury upon mixing seawater with groundwater. The mechanism of dissolved mercury removal was further elucidated by examining its relationships with both dissolved organic matter, dissolved manganese (Mn II), and redox potential. The flux of HgTD to the Bay of Puck was estimated to be 18.9 ± 6.3 g year-1. The submarine groundwater discharge-derived mercury load is substantially smaller than atmospheric deposition and riverine discharge to the Bay of Puck. Thus, groundwater is a factor that dilutes the mercury concentrations in pore water and, as a result, dilutes the mercury concentrations in the water column.

Nutrient fluxes via submarine groundwater discharge to the Bay of Puck, southern Baltic Sea.

Submarine groundwater discharge (SGD) has been recognized as an important exchange pathway between hydrologic reservoirs due to its impact on biogeochemical cycles of the coastal ocean. This study reports nutrient concentrations and loads delivered by SGD into the Bay of Puck, the southern Baltic Sea. Measurements were carried out between September, 2009 and October, 2010 at groundwater seepage sites identified by low salinity of pore water. Groundwater fluxes, measured using seepage meters, ranged from 3 to 22 L m(-2)day(-1). Average concentrations of nutrients in groundwater samples collected were as follows: 0.4 µmol L(-1) nitrate (NO(3)), 0.8 µmol L(-1) nitrite (NO(2)), 18.2 µmol L(-1) ammonium (NH(4)) and 60.6 µmol L(-1) orthophosphate (PO(4)). Levels of NH(4) and PO(4) were significantly higher in samples from SGD sites than in seawater. Seawater and SGD samples showed similar NO(2) concentrations but SGD samples exhibited lower NO(3) levels than those observed in seawater samples. Measured seepage water fluxes and nutrient concentrations were used to calculate nutrient loads discharged into the study area while the literature groundwater flux and the measured nutrient concentrations were used to estimate nutrient loads discharged into the Bay of Puck. The estimates suggest that SGD delivers a dissolved inorganic nitrogen (DIN) load of 49.9 ± 18.0 t yr(-1) and a PO(4)(-) load of 56.3 ± 5.5tyr(-1) into the Bay of Puck. The projected estimates are significant in comparison with loads delivered to the bay from other, well-recognized sources (705 ty r(-1) and 105 ty r(-1) respectively for DIN and PO(4)). Nutrient discharge input loads were projected to the entire Baltic Sea The extrapolated values indicate SGD contributes a significant proportion of phosphate load but only an insignificant proportion of DIN load. Further studies are necessary to better understand SGD contributions to the nutrient budget in the Baltic Sea.