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The cyclopoid copepod Apocyclops royi (Lindberg 1940) is one of two dominant mesozooplankton species in brackish Taiwanese aquaculture ponds. Periodically low n-3 polyunsaturated fatty acid (PUFA) content in seston could potentially be a limiting factor for zooplankton diversity. Apocyclops royi’s potential ability to biosynthesize n-3 PUFA was investigated through a short-term feeding experiment on four species of microalgae. Furthermore, we analyzed the expression of genes encoding putative fatty acid elongase (ELO) and desaturase (FAD) enzymes in A. royi on long-term diets of the PUFA-poor Dunaliella tertiolecta and the PUFA-rich Isochrysis galbana. The copepods exhibited high contents of docosahexaenoic acid (DHA, C22:6n-3) (>20% of total fatty acid) even when DHA-starved for two generations, and no significant differences were found in absolute DHA content between treatments. Transcripts correlating to the four enzymes Elovl4, Elovl5, Fad Δ5 and Fad Δ6 in the n-3 PUFA biosynthetic pathway were identified. Gene expression analysis revealed a significantly higher expression of two desaturases similar to Fad Δ6 in copepods fed PUFA-lacking algae compared to copepods fed algae with high PUFA content. These findings suggest a highly active n-3 PUFA biosynthesis and capability of DHA production in A. royi when fed low-PUFA diets.

In high-latitude fjord ecosystems, the spring bloom accounts for a major part of the annual primary production and thus provides a crucial energy supply to the marine food web. However, the environmental factors that control the timing and intensity of these spring blooms remain uncertain. In 2013, we studied the spring bloom dynamics in Godthabsfjord, a large fjord system adjacent to the Greenland Ice Sheet. Our surveys revealed that the spring bloom did not initiate in the inner stratified part of the fjord system but only started farther away from tidewater outlet glaciers. A combination of out-fjord winds and coastal inflows drove an upwelling in the inner part of the fjord during spring (April-May), which supplied nutrient-rich water to the surface layer. This surface water was subsequently transported out-fjord, and due to this circulation regime, the biomass accumulation of phytoplankton was displaced away from the glaciers. In late May, the upwelling weakened and the dominant wind direction changed, thus reversing the direction of the surface water transport. Warmer water was now transported toward the inner fjord, and a bloom was observed close to the glacier terminus. Overall, our findings imply that the timing, intensity, and location of the spring blooms in Godthabsfjord are controlled by a combination of upwelling strength and wind forcing. Together with sea ice cover, the hydrodynamic regime hence plays a crucial role in structuring food web dynamics of the fjord ecosystem.

Many tidewater outlet glacier fjords surround the coast of Greenland, and their dynamics and circulation are of great importance for understanding the heat transport toward glaciers from the ice sheet. Thus, fjord circulation is a critical aspect for assessing the threat of global sea level rise due to melting of the ice sheet. However, very few observational studies describe the seasonal dynamics of fjord circulation. Here we present the first continuous current measurements (April–November) from a deep mooring deployed in a west Greenland tidewater outlet glacier fjord. Four distinct circulation phases are identified during the period, and they are related to exchange processes with coastal waters, tidal mixing, and melt processes on the Greenland Ice Sheet. During early summer, warm intermediate water is transported toward the glacier at an average velocity of about 7 cm s−1. In late summer, the average velocity decreases to 3 cm s−1 during a period with significant subglacial freshwater discharges. During this period, a large variability in current velocities is also observed. The associated average heat transport in an intermediate-depth range corresponds to 568 GW in early summer and is reduced to 287 GW in late summer. These heat fluxes are at the higher end of previously reported fluxes. Our measurements show that the intermediate heat transport varies over time and during summer provides a major contribution to the heat budget and, thereby, potentially to glacial melt. We suggest that intermediate heat transport may play a similar important role in other fjords around Greenland. Many tidewater outlet glacier fjords surround the coast of Greenland, and their dynamics and circulation are of great importance for understanding the heat transport toward glaciers from the ice sheet. Thus, fjord circulation is a critical aspect for assessing the threat of global sea level rise due to melting of the ice sheet. However, very few observational studies describe the seasonal dynamics of fjord circulation. Here we present the first continuous current measurements (April–November) from a deep mooring deployed in a west Greenland tidewater outlet glacier fjord. Four distinct circulation phases are identified during the period, and they are related to exchange processes with coastal waters, tidal mixing, and melt processes on the Greenland Ice Sheet. During early summer, warm intermediate water is transported toward the glacier at an average velocity of about 7 cm s−1. In late summer, the average velocity decreases to 3 cm s−1 during a period with significant subglacial freshwater discharges. During this period, a large variability in current velocities is also observed. The associated average heat transport in an intermediate-depth range corresponds to 568 GW in early summer and is reduced to 287 GW in late summer. These heat fluxes are at the higher end of previously reported fluxes. Our measurements show that the intermediate heat transport varies over time and during summer provides a major contribution to the heat budget and, thereby, potentially to glacial melt. We suggest that intermediate heat transport may play a similar important role in other fjords around Greenland.

Although salt rejection from sea ice is a key process in deep-water formation in ice-covered seas, the concurrent rejection of CO(2) and the subsequent effect on air-sea CO(2) exchange have received little attention. We review the mechanisms by which sea ice directly and indirectly controls the air-sea CO(2) exchange and use recent measurements of inorganic carbon compounds in bulk sea ice to estimate that oceanic CO(2) uptake during the seasonal cycle of sea-ice growth and decay in ice-covered oceanic regions equals almost half of the net atmospheric CO(2) uptake in ice-free polar seas. This sea-ice driven CO(2) uptake has not been considered so far in estimates of global oceanic CO(2) uptake. Net CO(2) uptake in sea-ice-covered oceans can be driven by; (1) rejection during sea-ice formation and sinking of CO(2)-rich brine into intermediate and abyssal oceanic water masses, (2) blocking of air-sea CO(2) exchange during winter, and (3) release of CO(2)-depleted melt water with excess total alkalinity during sea-ice decay and (4) biological CO(2) drawdown during primary production in sea ice and surface oceanic waters.

METEOR-Berichte

Pga. minedrift og manglende spildevandshåndtering i lande som Bolivia, er adgangen til rent drikkevand begrænset, og det er derfor vigtigt for lokalbefolkningen at få et overordnet indblik i toksiciteten af deres vandressourcer, som ofte er overfladevand. På nuværende tidspunkt er anvendelsen af 1,5-Diphenylthiocarbazone (dithizon) kombineret med kloroform og 4-(2-Pyridylazo)resorcinol (PAR) individuelt til detektering af bl.a. kobber (Cu), kviksølv (Hg) og zink (Zn) vha. spektrofotometri, samt bestemmelse af toksiske niveau i både vand- og sedimentprøver er allerede veldokumenteret. Dog er reagenser som kloroform vanskelige at håndtere, en miljøbelastning ved udledning i naturen og der stilles derfor krav til kostelige permanente laboratoriemæssige faciliteter.Ved akutte toksicitetsanalyser hvor bl.a. koncentration med en dødelighed på 50% (LC50) bestemmes ved dosis-respons standard test med krebsdyret Daphnia Magna som testorganisme, bliver der allerede produceret kits med standardiseret analysemetoder.I dette studie præsenteres en billig og håndterbar måde, at bestemme koncentration af udvalgte metaller i overfladevand vha. bærbart PDA spektrofotometer (med laptop) og vha. en akut dosis-respons standard toksicitetstest, at få et indblik i vandets toksicitetsniveau i forbindelse indsamling af selve prøverne.Ved udvikling af multivariate analysemodeller ud fra spektrofotometriske absorptionsspektre af fortyndinger med koncentrationskombinationer med henholdsvis Cu2+, Hg2+ og Zn2+, er det muligt at måle koncentrationer på op til tre forskellige metaller ved én analyse. Ved at anvende en kombination af dithizon (kombineret med Triton X-100) og PAR, er det muligt at udnytte begge chelaters affinitet overfor forskellige metaller, og herved optimere analysemetoden.Der er fremstillet spektrofotometriske multivariate analysemodeller med en nedre detektionsgrænse på henholdsvis 18 µg/L for Cu, 21 µg/L Hg og 20 µg/L Zn ved pH 8,7, samt detektering af 70 µg/L Cu ved pH 2,5. Desuden er der ved akut toksicitetsanalyse indeholdende enkelte metalkoncentrationer, bestemt LC50-værdier for CuSO4 på henholdsvis 71 µg/L (efter 24 t), 42 µg/L (efter 48 t) og 35 µg/L (efter 72 t), samt for ZnCl2 på henholdsvis 232 µg/L (efter 24 t), 100 µg/L (efter 48 t) og 95 µg/L (efter 72 t).Hvor den spektrofotometriske analyse fokuserer på koncentrationen af specifikke udvalgte metaller, kan den akutte toksicitetsanalyse anvendes som standard test med et bredere perspektiv, da der her fokuseres på vandprøvens overordnede toksiske niveau.Ved at kombinere analysemetoderne er det muligt både at bestemme udvalgte metalkoncentrationer og få et overblik ift. toksicitetsniveau, der bl.a. kan detektere Cu2+- og Zn2+-koncentrationer, der er lavere end anbefalede kvalitetsstandarder for drikkevand ifølge United States Environmental Protection Agency (USEPA) og World Health Organization (WHO), hvilket betyder, at metoden kan anvendes som retningslinje ift. de officielle drikkevandsstandarder., In developing countries like Bolivia, access to clean drinking water may be limited, because of mining and lack of wastewater management. Therefore, it is important for the local communities to get knowledge about the toxicity of the water resources, which is often surface water. Up to now, the application of detecting of copper (Cu), mercury (Hg) and zinc (Zn) with spectrophotometric analysis by using 1,5-Diphenylthiocarbazone (dithizone) combined with chloroform or 4-(2-Pyridylazo)resorcinol (PAR) individually, as well as detection of a toxic level in both water- and sediment samples are already well documented, but reagents as like chloroform are difficult to handle. By leading chloroform into nature will cause an environmental risk and therefore, it will require permanent laboratory facilities to use spectrophotometric analysis. By acute toxicity analysis by detecting the metal concentration by determining the median lethal concentration (LC50), it is possible to use a dose-response standard test with the crustaceans as Daphnia Magna as the test organism. Kits for that purpose are already produced with standardized analysis methods.This study will present a cheap and manageable way to detect the concentration of selected metals in surface water by a PDA spectrophotometer (connected to a laptop) and by an acute dose-response standard toxicity test to get a knowledge of the toxicity level of the surface water when collecting the samples.By developing multivariate analyze models by the spectrophotometric absorption spectrum of dilutions with combinations of Cu2+, Hg2+, and Zn2+, it is possible to measure up three different metals by one analysis. By using a combination of dithizone (combined with Triton X-100) and PAR, it is possible to exploit the different chelators affinity to different metal ions.By this study, spectrophotometric multivariate analysis models are developed with a lower detection limit of 18 µg/L for Cu, 21 µg/L Hg, 20 µg/L Zn at pH 8,7, and a detection limit of 70 µg/L Cu at pH 2,5.Furthermore, in acute toxicity analysis containing single metal concentrations, the detection of LC50 values of CuSO4 are 71 µg/L (after 24 h), 42 µg/L (after 48 h) and 35 µg/L (after 72 h). the detection of LC50 values of ZnCl2 are 232 µg/L (after 24 h), 100 µg/L (after 48 h) and 95 µg/L (after 72 h).The spectrophotometric analysis focuses on the concentration of specifically selected metals, and the acute toxicity analysis can be used as a standard test with a broader perspective, by testing the total toxically level of the water sample. By combining the methods of analysis, it is possible to determine, both selected metal concentrations and obtain an overview of the toxicity level. It is possible to detect concentrations of copper and zinc lower than recommended drinking water quality standards according to the United States Environmental Protection Agency (USEPA) and the World Health Organization (WHO) ensuring the method can be used as a guideline in relation to the official drinking water standards.

Decomposition rates of organic matter in Danish salt marsh sediment were measured in this study using a flow through reactor (FTR) experimental setup. Four different treatments using single and multiple terminal electron acceptors (TEA) were prepared. One treatment was aerobic, whilst the remaining were anaerobic. The consumption of different TEAs (nitrate, oxygen and sulfate) and the production of carbon dioxide were measured over a period of 38 and 66 days in two experiments. The mean (± SEM) nitrate consumption rate was 21.5 ± 3 nmol cm-3 h-1 when only nitrate was available and 23.8 ± 3.48 nmol cm-3 h-1 when both nitrate and sulfate was available. The mean (±SEM) oxygen consumption rate was 13.4 ± 0.88 nmol cm-3 h-1. Using both ion-chromatography and a new method based upon precipitation of barium sulfate and flame atomic absorption spectroscopy (fAAS) sulfate was analyzed. Neither of the two methods gave reliable measurements of the sulfate consumption rate, however, as the deviations in the measurements were greater than the changes due to consumption. The fAAS method does, however, hold a great potential for situations where hundreds of samples needs to be analyzed but further investigation is required before it can be implemented. To compare the different treatments carbon dioxide production was measured. A new method for measuring carbon dioxide in aqueous solution was developed. It uses a Gas Sensor Infrared electrode (GSIRe), and a custom apparatus. The method was found to agree well with the already established Gran titration in the range of 0-5 mM CO_3^(2-). Using this new method, combined with the TEA consumption rates, dissolution of CaCO3 was identified to contribute approximately 60 % of the total production of carbon dioxide. Despite this contribution from the dissolution of CaCO3, the aerobic treatment used in the setup was over time found to produce significantly more carbon dioxide than the two anaerobic treatments containing either nitrate or sulfate as TEA. The daily production of carbon dioxide gave mean (± SEM) of the aerobic treatment of 127.92 ± 3.38 nmol cm-3 h-1 whilst the treatments containing either sulfate or nitrate gave 101.1 ± 2.96 and 94.66 ± 2.49, respectively. The treatment containing both nitrate and sulfate had 117.51 ± 2.73 nmol cm-3 h-1. The decomposition rates were similar in the start of the experiment for all treatments and over time the aerobic treatment become more productive than the remaining treatments. The experimental evidence did support the idea that high levels of nitrate would increase rates of salt marsh decomposition compared to sulfate reduction alone.

This thesis is based on 35 natural Emiliania huxleyi DNA samples and corresponding water samples from the North Atlantic Ocean, on a stretch between Bermuda and the Azores. Water samples were analysed for concentrations of the seven most dominant ionic species in seawater; Cl-, Na+, SO42-, Mg2+, Ca2+, K+ and HCO3-, which are also the ions that contribute the most to the salinity of solution. Distinction was made between practical salinity and absolute salinity, values were obtained for both, compared and the importance of differences discussed. pH, temperature and chlorofyll content were also measured. Methods used were atomic absorption spectroscopy, ion chromatography, titration, pH electrode, Sea-Bird Electronics CTD and ion selective electrodes. E. huxleyi strain CCMP371 was cultured at 20 °C, 16/8 - light/dark cycle with L1 medium of salinity 25 ‰. E. huxleyi cell numbers were obtained for 13 natural samples using qPCR. Qualitative exploration of data showed no obvious connections between cell numbers and specific ion concentrations, although indications of some connection between pH and cell numbers were observed. Ion selective electrodes were not suitable for measuring ion concentrations in seawater due to ion specificity issues. It was concluded that the chosen ionic species probably does not alone determine the presence of E. huxleyi, many other factors have importance, which could not be included in this project. Futher research would have to include all factors or experiments be conducted under controlled laboratory conditions.

Oil spilled into the aquatic environment is susceptible to various types of weathering. Some of these move the compounds, where others degrade them. Overall the weathering processes change the chemical composition of the remaining oil by removing specific compounds. In this thesis the weathering processes evaporation, dissolution, photooxidation and microbial degradation were simulated in vitro. The objective for this was to evaluate the relative chemical compositional changes in the remaining oil as a function of weathering processes. Based on the information of these a model was created, describing effects of natural weathering on a heavy fuel oil. The model was evaluated through analysis of naturally weathered oil samples. The effects of the weathering processes were monitored by gas chromatography – mass spectrometry operating in selected ion monitoring mode. Selected parts of ion chromatograms were preprocessed through a new integrated methodology using correlation optimised warping, which made principal component analysis (PCA) based on chemical patterns of the total ion chromatograms possible. The PCA clearly modelled the individual weathering processes as functions of exposure time, and was validated by separating the long term and short term naturally weathered oil samples. Altogether, the preprocessing methodology was capable of eliminating the concentration effects, optimising signal-to-noise ratios, reducing effects of tailing, presenting chromatographic data across several hundred analyses that were comparable by PCA, and at the same time separate data that possesses high degrees of uncertainty from accurate and useful data.