Deep impact? Is mercury in dab (Limanda limanda) a marker for dumped munition? Results from munition dump site Kolberger Heide (Baltic Sea).

Dumped munitions contain various harmful substances which can affect marine biota like fish. One of them is mercury (Hg), included in the common explosive primer Hg fulminate. There is still a lack of knowledge whether dumped munitions impact the Hg concentrations in the Baltic Sea environment. This study aims to answer the question if dab caught at the dump site Kolberger Heide show higher Hg concentrations released from munition sources and whether Hg in fish is a usable marker for munition exposure. Therefore, a total of 251 individual dab (Limanda limanda) were analysed including 99 fish from the dump site. In fish from the Kolberger Heide, no elevated Hg concentrations were found compared to reference sites when age-dependent bioaccumulation of mercury was considered. Therefore we conclude that Hg in fish is no suitable indicator for exposure to munition dumping, e.g. in the frame of possible future monitoring studies as Hg exposure originating from dumped munition is only a small contributor to overall Hg exposure of fish.

Comparison between the Baltic Sea and Irish Sea level of Cs-137 contamination on benthic, demersal and pelagic fish species.

The Irish Sea and the Baltic Sea are nowadays still the two most Cs-137 contaminated Seas worldwide. However, the origins of this contaminations are completely different. While the Baltic Sea was unintentionally contaminated due to global fallout after the accident in the Chernobyl nuclear powerplant in 1986, the Irish sea was intentionally used for low level liquid radioactive waste discharges from the Sellafield nuclear reprocessing facility (called Windscale until 1981) between the 1950s and 1990s. Nowadays, more than 30 years later, it is still possible to detect these contaminations in fish, water and sediments of both seas. Since fish are an important part of the human diet, monitoring Cs-137 levels in fish is essential for assessing the potential radiation exposure to humans. In 2019 and 2020 two surveys were dedicated to study the current levels of radioactive contamination in fish species from both Seas. During both surveys, fish samples were collected and analysed by gamma spectrometry later on. The results show that the average Cs-137 activity in benthic, demersal and pelagic fish species from the Baltic Sea are 2.7, 4.6 and 4.2, respectively, times higher than the corresponding values of the Irish Sea. Based on this and two other comparisons, it is concluded that the Baltic Sea is the most contaminated with Cs-137.

Visual quantification and identification of shallow seafloor marine litter in the southernmost North and Baltic seas using an epibenthic video sledge (EVS) - A comparison to bottom trawl data.

The quantification of the marine litter at the seafloor is a challenging process. Currently the majority of the data of marine litter at the seafloor is a by-product of bottom trawl fish stocks assessment. In the search for a new, less invasive and universally usable method, an epibenthic video sledge was used to make video recordings of the seafloor. With these videos a visual estimation of the marine litter in the southernmost North and Baltic seas was done. The estimated mean litter abundances with 526.8 litter items (LI)·km-2 in the Baltic Sea and 305.1 LI·km-2 in the North Sea are significantly higher compared to bottom trawl studies. Using both results conversion factors for marine litter catch efficiency of two fishing gears were calculated for the first-time. These new factors now allow obtaining more realistic quantitative data of seafloor litter abundance.

Abandoned, lost or otherwise discarded fishing gear (ALDFG) as part of marine litter at the seafloor of the Baltic Sea - Characterization, quantification, polymer composition and possible impact.

As an important part of marine litter at the seafloor "Abandoned, lost, discarded or otherwise lost fishing gear" (ALDFG) is gaining increasing attention in environmental assessments. Within this study marine litter at the seafloor of the Baltic Sea was quantified and characterized with special regard to fishery as source. Litter items (LI) were collected within fishery catches by bottom trawling during three cruises in 2020 and 2021. The resulting mean litter abundance was 9.2 LI/km2. Approximately 56 % of all LI were plastic, with PE as the most frequently identified polymer. ALDFG was present in considerable amounts with a mean value of 2.2 LI/km2 (22.2 %). However, the absolute counts of fishery nets were low (0.4 LI/km2; 4.2 %). Regarding weight, fishery nets are the dominant part of litter at the Baltic seafloor. Threshold values for marine litter at the seafloor are missing and might be developed using quantitative data on ALDFG.

Marine litter at the seafloor - Abundance and composition in the North Sea and the Baltic Sea.

Litter is present in all marine waters around the globe. It consists of several compound classes of which plastic is of special interest because of its high abundance and possible threat to marine organisms. The regional distribution, composition and abundance of large litter items (LI) at the sea floor of the North Sea and the Baltic Sea were investigated based on 175 bottom trawls between 2013 and 2015. Different types of marine litter >2.5cm were classified according to the protocol of the ICES International Bottom Trawl Survey. The results showed considerable geographical variation: In the North Sea, a mean litter abundance of 16.8LI/km2 was found, whereas the litter abundance in the Baltic Sea was significantly lower (5.07LI/km2). In general, plastic represented 80% of the litter items. During the study, some methodical aspects with possible impact on the results were identified that need to be addressed in future sampling campaigns.

Large scale distribution of dioxins, PCBs, heavy metals, PAH-metabolites and radionuclides in cod (Gadus morhua) from the North Atlantic and its adjacent seas.

Regarding cod as sea food for human consumption and as bio indicator of the marine eco system, this study is the first approach to combine the analysis of organic and inorganic contaminants and radionuclides in cod muscle as well as PCDD/Fs and dl-PCBs in its livers from the same fishing areas. Concentrations of 1-hydroxypyrene, PCDD/Fs, PCBs, cesium-137 (Cs-137), cadmium and lead were determined in individual or pooled samples over a wide geographic area, including Greenland Seas, Barents Sea, North and Baltic Sea. Highest concentrations were found in samples from the Baltic Sea, lowest in the pristine areas of the Barents Sea and Greenland. Levels of contaminants in cod muscle were found to be far below the established EU maximum levels (ML), regardless of which fishing grounds. In contrast to this, most cod liver samples from the North and Baltic Sea showed PCDD/F and PCB contents exceeding the ML. In addition, new background assessment criteria (BAC) for 1-hydroxypyrene in cod of 4.6 ng mL(-1) bile and for Cs-137 a BAC of 0.16 Bq kg(-1) wet weight are proposed to be included in the European Marine Strategy Framework Directive for cod from the Northeast Atlantic.

Metabolites from fungal laccase-catalysed transformation of sulfonamides.

Soil metabolism of sulfonamides is largely unknown. Hence the sulfonamides sulfanilamide (SAA), sulfadimethoxine (SDT) and sulfapyridine (SPY) were reacted in model experiments with a fungal laccase from Trametes versicolor. Enzymatic transformation after a reaction time of 15 d ranged from 10.0% for SAA up to 95.6% for SPY and the difference was attributed to the different molecular substituents. Metabolites were first tentatively assigned after LC-ESI(+)-MS full-scan analysis. Secondly, the proposed metabolites were further confirmed employing either multiple reaction monitoring in comparison with standard substances or precursor ion scan LC-ESI(+)-MS/MS experiments striving for the precursor and two to three product ions. Aniline was confirmed as a breakdown product of SPY and further metabolites of SPY and of SDT were identified as rearranged SO(2) extrusion products. Thirdly, some of the metabolites matched those that were previously reported for sulfonamide photodegradation and degradation in soil. It was concluded that enzymatic metabolism as investigated here also occurs in soil.

Composition of organic matter in particle size fractionated pig slurry.

Pig slurry is a heterogeneous mixture of different particle sizes that will have different mobility in soil. Therefore, a physically fractionated pig slurry sample was analysed, e.g. using pyrolysis-field ionisation mass spectrometry (Py-FIMS) in an effort to identify relationships between particle size and composition of organic matter. The presumably most mobile fractions in soils (<63 microm) accounted for approximately 50% of slurry dry matter and were dominated by lignins, and N-containing compounds. Sterols were especially abundant in the larger-sized fractions, which corresponds to their reported distribution in soils and surface waters. The averaged molecular masses indicated similarities of fractions <10 microm to aquatic humic substances and increasing content of plant material with increasing particle size. A statistical analysis of the compound class distribution revealed that the analysis of three particle size fractions is essential for the assessment of the composition and properties of slurry constituents.

Distribution of sulfamethazine, chlortetracycline and tylosin in manure and soil of Canadian feedlots after subtherapeutic use in cattle.

Feedlots are potential point sources for the flow of antibiotics into the environment due to common use of antibiotics such as sulfamethazine, chlortetracycline and tylosin. Hence soils and manures originating from a grassland control, an experimental and a commercial feedlot were analyzed and mass balances were calculated for these antibiotics. Up to 9990 microg kg(-1) sulfamethazine and 401microg kg(-1) chlortetracycline on a dry matter basis were determined in feedlot manure. Soil concentrations were two orders of magnitude smaller. This corresponds to 7-40% of the calculated residual amount. In the commercial feedlot chlortetracycline was found down to soil depths of -40 cm; sulfamethazine was still detectable 1 year after medication. Sulfamethazine and chlortetracycline were additionally determined in manure of a control treatment in the experimental feedlot where cattle never received antibiotics. This was attributed to runoff from upslope pens. Consequently, antibiotics partially persist within feedlots and may be dislocated into the surrounding environment by vertical transport and runoff.