Sorption of Cr, Pb, Cu, Zn, Cd, Ni, and Co to nano-TiO2 in seawater.

In this study, the role of nanoparticles in complex aqueous matrices such as the Baltic Sea was investigated in batch-mode experiments in which titanium dioxide nanoparticles (nano-TiO2) were tested for their ability to remove heavy metals (Cr, Pb, Cu, Zn, Cd, Ni, Co) from multicomponent spiked and non-spiked Baltic Sea water. The experimental data were analyzed using different isotherms (Langmuir, Freundlich, Dubinin-Kaganer-Radushkevich (DKR)) and models (pseudo-first-order and pseudo-second-order models, the double-exponential model, and the Weber-Morris model). The equilibria and kinetic investigations showed that metal sorption to nano-TiO2 occurs in a two-step, multilayer process and that there is strong competition for sorption sites. The results of the DKR isotherm and dilution experiment indicated weak electrostatic bonds, except for Pb. The distribution coefficient values (1.8 × 103 to 2.8 × 105 ml g-1) were consistent with the good sorbent properties of nano-TiO2 and supported the use of the particles in seawater purification technologies. However, metal-enriched nano-TiO2 may also act as an effective carriers of metals to marine sediments, which could increase their availability to benthic organisms.

Pockmarks and associated fresh submarine groundwater discharge in the seafloor of Puck Bay, southern Baltic Sea.

This is the first well-documented report on the occurrence of pockmarks in Puck Bay. Pockmarks in the seafloor of Puck Bay were discovered during a hydroacoustic survey carried out in 2020. They are located at a depth of 25-27 m in the southwestern part of the bay. Significant depletion of chloride (Cl-) concentrations in sediment pore water was found within the depressions. Most likely, the formation of pockmarks was due to groundwater flow through the Miocene-Pleistocene system of aquifers, which extends from land to the bay area. One-dimensional modeling of vertical Cl- concentration profiles in pore water revealed the upward flow of freshened groundwater within the pockmarks. The magnitude of submarine groundwater discharge (SGD) was estimated to vary from 1.53·10-2 to 18·10-2 L·m-2·h-1. The effect of groundwater seepage was also observed at 3 cm above the seafloor within the pockmarks, which was identified as a decrease in salinity of approximately 0.12 PSU compared to reference sites. Furthermore, due to the effect of water advection, SGD can be detected even several meters above the seafloor as a decrease in salinity values within the thermocline layer.

Biodiversity of microorganisms in the Baltic Sea: the power of novel methods in the identification of marine microbes.

Until recently, the data on the diversity of the entire microbial community from the Baltic Sea were relatively rare and very scarce. However, modern molecular methods have provided new insights into this field with interesting results. They can be summarized as follows. (i) Although low salinity causes a reduction in the biodiversity of multicellular species relative to the populations of the North-East Atlantic, no such reduction occurs in bacterial diversity. (ii) Among cyanobacteria, the picocyanobacterial group dominates when considering gene abundance, while filamentous cyanobacteria dominate in means of biomass. (iii) The diversity of diatoms and dinoflagellates is significantly larger than described a few decades ago; however, molecular studies on these groups are still scarce. (iv) Knowledge gaps in other protistan communities are evident. (v) Salinity is the main limiting parameter of pelagic fungal community composition, while the benthic fungal diversity is shaped by water depth, salinity, and sediment C and N availability. (vi) Bacteriophages are the predominant group of viruses, while among viruses infecting eukaryotic hosts, Phycodnaviridae are the most abundant; the Baltic Sea virome is contaminated with viruses originating from urban and/or industrial habitats. These features make the Baltic Sea microbiome specific and unique among other marine environments.

Polymorphism of CaCO3 and the variability of elemental composition of the calcareous skeletons secreted by invertebrates along the salinity gradient of the Baltic Sea.

Biomineralization is of great importance in ecosystem functioning and for the use of carbonate skeleton as environmental proxies. Skeletal formation is controlled to different degrees by environmental parameters and biological mechanisms. While salinity is one of the most important factors affecting ecological processes and ocean physiochemistry, the goal of this investigation was to identify how salinity influences the mineral type and the concentrations of chemical elements in the whole skeleton of invertebrates from the Baltic Sea. In this model system, the surface salinity decreases from marine values (27.2) to almost fresh water (6.1). The selected organisms, mussels (Mytilus spp.), bryozoans (Einhornia crustulenta, Cribrilina cryptooecium, Cryptosula pallasiana, Electra pilosa, Escharella immersa), barnacles (Amphibalanus improvisus, Semibalanus balanoides), and polychaetes (Spirorbis tridentatus), precipitated skeleton composed of calcite and aragonite, most likely as a result of various interacting environmental and biological factors. The concentrations of all elements in bulk skeleton were highly variable between species from the same location, underlining the role of the biological mechanisms in skeletal formation. The concentration of Ca, Mg, Sr, and Na increased in the bulk skeleton of stenohaline organisms with increasing salinity, while in the bulk skeleton of euryhaline species, only the concentration of Na increased with increasing salinity. The concentrations of Mn, Ba, Cu, Pb, Y, V, Cd, and U in the skeleton of euryhaline species generally decreased at higher salinities, most likely reflecting the lower bioavailability of elements at higher salinity. However, the concentrations of elements in the skeleton of stenohaline organisms were highly variable with no clear salinity impact. This study suggests that, although the composition of skeleton of calcifying organisms along the salinity gradient of the Baltic Sea is to a large extent affected by biological mechanisms, it also reflects the responses to environmental conditions.

Submarine groundwater discharge as a source of pharmaceutical and caffeine residues in coastal ecosystem: Bay of Puck, southern Baltic Sea case study.

Even though the occurrence of pharmaceuticals in the water environment is thought to be a potential problem for human health and aquatic organisms, the level of knowledge of their sources and presence in the marine ecosystem is still insufficient. Therefore, this study was designed to determine the emergence of sixteen pharmaceuticals and caffeine in groundwater, submarine groundwater discharge (SGD), rivers and coastal seawater in the southern Baltic Sea. It has been recognized that chemical substances load associated with SGD can affect coastal ecosystems equally or even greater than surface runoff. Hence, the Bay of Puck, which is an active groundwater discharge area, has been chosen as a model study site to assess the preliminary risk of pharmaceutical and caffeine residues supply in coastal ecosystem. A special focus was placed on tracing the possible sources of pollution for groundwater and SGD based on the composition of collected samples. Five pharmaceuticals (carbamazepine, sulfapyridine, sulfamethoxazole, ketoprofen and diclofenac) and caffeine were detected in varying concentrations from below the detection limit to 1528.2 ng L-1. Caffeine and diclofenac were the most widespread compounds. Groundwater was mostly enriched in the analysed compounds and consequently SGD has been recognized as an important source of identified pharmaceutical and caffeine residues to the Bay of Puck. A predicted no-effect concentration (PNEC) was determined in order to perform an environmental risk assessment of five pharmaceuticals and caffeine detected in water samples. Finally, future challenges and potential amendments in monitoring strategies are discussed.

Legacy and emerging pollutants in the Gulf of Gdansk (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 Gdansk 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 Gdansk 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.

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.

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.