Marta Szubska

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.

Seasonal changes of mercury speciation in the coastal sediments

PurposeMercury speciation in sediments is linked to environmental conditions and processes. Domination of particular mercury species depends on its source, displays considerable seasonal behavior, and may be further modified due to oxygen levels, icing conditions, or the input of fresh organic matter. The purpose of this study was to examine the coastal area of the Gulf of Gdańsk in terms of mercury contamination and the influence of seasonal environmental changes on its speciation.Materials and methodsIn three highly dynamic coastal sites, mercury speciation in sediments was studied in relation to other environmental parameters (redox conditions, organic matter concentration, bacteria abundance, etc.). Sediment and water samples were collected monthly during a 3-year study. Sequential extraction of sediments was used for identification of four inorganic mercury species: dissolved, bound with fulvic and humic acids, mercury sulfide, and residual fraction. Cold vapor atomic fluorescence spectrometry (CV-AFS) was used for extracts and liquid sample analysis. Total mercury in sediments was measured with atomic absorption spectrometry (AAS). Changes in salinity were analyzed by measurements of chloride and sulfate ion concentrations using ion chromatography. Bacteria number and biomass were measured by direct counting using epifluorescence microscopy.Results and discussionSeasonal changes in mercury speciation were observed at all sites and attributed to different processes. Labile mercury fraction contribution varied from 0 to 80%. The speciation patterns varied locally as the stations selected for the study are diversified in terms of anthropogenic impact, water dynamics, and output from land. Mercury concentrations at all stations fluctuated during phytoplankton blooms, icing of marine waters, precipitation, or increased surface runoff from the land. In this local scale, the global climate changes are visible already as environmental conditions in studied area changed in comparison to elder research.ConclusionsObtained results suggest that although mercury emissions to the environment have decreased in recent years, local weather conditions, which may be intensified by climate change, seriously affect the bioavailability of past mercury deposits in coastal sediments.

Deep sea habitats in the chemical warfare dumping areas of the Baltic Sea

The Baltic Sea is a severely disturbed marine ecosystem that has previously been used as a dumping ground for Chemical Warfare Agents (CW). The presence of unexploded underwater ordnance is an additional risk factor for offshore activities and an environmental risk for the natural resources of the sea. In this paper, the focus is on descriptions of the marine habitat based on the observations arising from studies linked to the CHEMSEA, MODUM and DAIMON projects. Investigated areas of Bornholm, Gotland and Gdańsk Deeps are similarly affected by the Baltic Sea eutrophication, however, at depths greater than 70m several differences in local hydrological regimes and pore-water heavy metal concentrations between those basins were observed. During the lifespan of presented studies, we were able to observe the effects of Major Baltic Inflow, that started in December 2014, on local biota and their habitats, especially in the Bornholm Deep area. Reappearance of several meiofauna taxa and one macrofauna specimen was observed approximately one year after this phenomenon, however its ecological effects already disappeared in March 2017. According to our findings and to the EUNIS Habitat Classification, the three reviewed areas should be characterized as Deep Sea Muddy Sands, while the presence of suspicious bomb-like objects both beneath and on top of the sediments confirms their CW dumpsite status.

Chemical Analysis of Dumped Chemical Warfare Agents During the MODUM Project

MODUM project continued the work on monitoring of the chemical weapons (CW) dumped in the Baltic Sea started in previous projects. As a new aspect, on board analysis methods – headspace gas chromatography-mass spectrometry (GC–MS) and capillary electrophoresis (CE) – were developed and tested in laboratory conditions and during cruises. The GC–MS method could be successfully applied on board to verify that collected sediment samples contained degradation products for sulfur mustard, one of the major chemical warfare agents dumped in Baltic Sea. This method could in future project be used during cruises to redirect sample collection in order to make most of the available ship time. Other part of the analysis task during MODUM project was the work done at the reach back laboratories. These analyses were done to both verify the results obtain on board and to fully identify the chemicals related to the sea-dumped CW agents. Reach back analysis of CW-related chemicals were done on sediment samples collected around a wreck in Bornholm Deep (same samples as analyzed on board) and on monitoring samples collected in Bornholm, Gotland and Gdansk Deeps. The samples from Bornholm and Gotland Deeps are in line with previous findings. Samples from Gdansk Deep are in line with previous findings that this area has been used as a dump site. Additionally, α-chloroacetophenone (CN) was found in the area for the first time. In addition to the analysis of CW-related chemicals, a new method was developed for measurement for arsenic concentrations in sediment samples. A method was also developed for arsenic speciation, which could help in estimation of the source of arsenic in the sediments.

Arsenic in the Environment of the Baltic Sea—A Review

Arsenic is an ubiquitous element, naturally occurring in all compartments of the environment. In marine ecosystems its concentrations are even one order of magnitude higher than in terrestrial environments, as arsenic entering the global cycle is eventually transported to the oceans where it bounds with sediments. It is toxic to many marine organisms, and consequently via the food web it might create risk for fish consumers. Seafood is the main source of arsenic in human organism; therefore, investigating arsenic transformations in marine environment is very important. Baltic Sea is a very specific water body. Geographical position, geological development, hydrographical features and physical drivers together make it very susceptible to pollutants, including arsenic contamination. In the case of Baltic Sea there is an additional source of arsenic—arsenic containing chemical weapon deposited on the sea bottom after the World War II. The aim of this article was to summarize the knowledge on arsenic behavior in the Baltic Sea gained by many researchers through the years. An effort was given to synthesize the information regarding arsenic concentrations in Baltic water, bottom sediments and marine organisms. Comparing with other marine areas, arsenic occurs in the Baltic Sea in relatively low concentrations, however in some regions (Bothnian Bay) the contamination with arsenic is significant and can pose a threat to organisms.