Chemical characterization of dissolved organic compounds from coastal sea surface microlayers (Baltic Sea, Germany)

The physicochemical properties of the sea surface microlayer (SML), i.e. the boundary layer between the air and the sea, and its impact on air-sea exchange processes have been investigated for decades. However, a detailed description about these processes remains incomplete. In order to obtain a better chemical characterization of the SML, in a case study three pairs of SML and corresponding bulk water samples were taken in the southern Baltic Sea. The samples were analyzed for dissolved organic carbon and dissolved total nitrogen, as well as for several organic nitrogen containing compounds and carbohydrates, namely aliphatic amines, dissolved free amino acids, dissolved free monosaccharides, sugar alcohols, and monosaccharide anhydrates. Therefore, reasonable analytical procedures with respect to desalting and enrichment were established. All aliphatic amines and the majority of the investigated amino acids (11 out of 18) were found in the samples with average concentrations between 53 ng/l and 1574 ng/l. The concentrations of carbohydrates were slightly higher, averaging 2900 ng/l. Calculation of the enrichment factor (EF) between the sea surface microlayer and the bulk water showed that dissolved total nitrogen was more enriched (EF: 1.1 and 1.2) in the SML than dissolved organic carbon (EF: 1.0 and 1.1). The nitrogen containing organic compounds were generally found to be enriched in the SML (EF: 1.9-9.2), whereas dissolved carbohydrates were not enriched or even depleted (EF: 0.7-1.2). Although the investigated compounds contributed on average only 0.3% to the dissolved organic carbon and 0.4% to the total dissolved nitrogen fraction, these results underline the importance of single compound analysis to determine SML structure, function, and its potential for a transfer of compounds into the atmosphere.

Composition of organic carbon at ODP Site 128-798

Organic geochemical and sedimentological investigations have been performed on sediments from ODP Sites 798 and 799 in order to reconstruct the depositional environment in the Japan Sea through late Cenozoic times. The Miocene to Quaternary sediments from Site 798 (Oki Ridge) and Site 799 (Kita-Yamato Trough) are characterized by high organic carbon contents of up to 6%. The organic matter is mainly a mixture of marine and terrigenous material. The dominant factors controlling marine organic carbon enrichment in the sediments of Hole 798A are probably an increased surface-water productivity and/or an increased preservation rate of organic carbon under anoxic deep-water conditions. In lower Pliocene sediments at Site 798 and Miocene to Quaternary sediments at Site 799, rapid burial of organic matter in turbidites may have been important, too. Remarkable cycles of dark, laminated sediments distinctly enriched in (marine) organic carbon by up to 5% and light, bioturbated to homogeneous sediments with reduced organic carbon contents indicate dramatic short-term paleoenvironmental variation.

Dissolved organic matter in the Lena Delta in 2009

Large Arctic rivers discharge significant amounts of dissolved organic matter (DOM) into the Arctic Ocean. We sampled natural waters of the Lena River, the Buor-Khaya Bay (Laptev Sea), permafrost melt water creeks, ice complex melt water creeks and a lake. The goal of this study was to characterize the molecular DOM composition with respect to different water bodies within the Lena Delta. We aimed at an identification of source-specific DOM molecular markers and their relative contribution to DOM of different origin. The molecular characterization was performed for solid-phase extracted DOM by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Average dissolved organic carbon concentrations in the original samples were 490±75 µmol C/L for riverine and bay samples and 399±115 µmol C/L for permafrost melt water creeks. Average TDN concentrations were elevated in the permafrost melt waters (19.7±7.1 µmol N/L) in comparison to the river and the bay (both 13.2±2.6 µmol N/L). FT-ICR MS and statistical tools demonstrated that the origin of DOM in the Lena Delta was systematically reflected in its molecular composition. Magnitude weighted parameters calculated from MS data (O/Cwa, H/Cwa, C/Nwa) highlighted preliminary sample discrimination. The highest H/Cwa of 1.315 was found for DOM in melt water creeks in comparison to 1.281 for river and 1.230 for the bay samples. In the bay samples we observed a higher fraction of oxygen-rich components which was reflected in an O/Cwa ratio of 0.445 in comparison to 0.425 and 0.427 in the river and creeks, respectively. From the southernmost location to the bay a relative depletion of nitrogenous molecular markers and an enrichment of oxidized DOM components occurred. The highest contribution of nitrogenous components was indicative for creeks reflected in a C/Nwa of 104 in comparison to 143 and 176 in the river and bay, respectively. These observations were studied on a molecular formula level using principal component and indicator value analyses. The results showed systematic differences with respect to water origin and constitute an important basis for a better mechanistic understanding of DOM transformations in the changing Arctic rivers.

Organic geochemistry of Late Cretaceous to Paleogene sediments from MITI Sanriku-oki borehole

Perylene is present in high concentration in Paleogene sediments from the Sanriku-oki borehole of the Ministry of International Trade and Industry (MITI), northeastern Japan. The borehole penetrates a thick sequence of Late Cretaceous to Neogene sediments deposited under a range of conditions, including fluvial-deltaic and shallow marine. Organic petrological and geochemical data show the sediments to be rich in organic matter (OM) derived from higher plants. Biomarker analysis of aliphatic and aromatic hydrocarbons confirms a significant input from higher plants, with extracts dominated by numerous gymnosperm- and angiosperm-derived biomarkers such as diterpanes, oleanenes, des-A-triterpanes and their aromatized counterparts. The highest concentration of perylene occurs in Middle Eocene sediments deposited in a relatively reducing environment. Stable carbon isotope compositions show 13C enrichment in perylene compared to gymnosperm and angiosperm biomarkers, consistent with a fungal origin. This elevated abundance of sedimentary perylene could relate to a Paleogene continental climate where fungi probably flourished.

PeECE I - Pelagic Ecosystem CO2 Enrichment Study, Raunefjord, Bergen, Norway, 2001

The effects of CO2-induced seawater acidification on plankton communities were also addressed in a series of 3 mesocosm experiments, called the Pelagic Ecosystem CO2 Enrichment (PeECE I-III) studies, which were conducted in the Large-Scale Mesocosm Facilities of the University of Bergen, Norway in 2001, 2003 and 2005, respectively. Each experiment consisted of 9 mesocosms, in which CO2 was manipulated to initial concentrations of 190, 350 and 750 µatm in 2001 and 2003, and 350, 700 and 1050 µatm in 2005. The present dataset concerns PeECE I.

CO2 and inorganic nutrient enrichment affect the performance of a calcifying green alga and its noncalcifying epiphyte

Ocean acidification studies in the past decade have greatly improved our knowledge of how calcifying organisms respond to increased surface ocean CO2 levels. It has become evident that, for many organisms, nutrient availability is an important factor that influences their physiological responses and competitive interactions with other species. Therefore, we tested how simulated ocean acidification and eutrophication (nitrate and phosphate enrichment) interact to affect the physiology and ecology of a calcifying chlorophyte macroalga (Halimeda opuntia (L.) J.V. Lamouroux) and its common noncalcifying epiphyte (Dictyota sp.) in a 4-week fully crossed multifactorial experiment. Inorganic nutrient enrichment (+NP) had a strong influence on all responses measured with the exception of net calcification. Elevated CO2 alone significantly decreased electron transport rates of the photosynthetic apparatus and resulted in phosphorus limitation in both species, but had no effect on oxygen production or respiration. The combination of CO2 and +NP significantly increased electron transport rates in both species. While +NP alone stimulated H. opuntia growth rates, Dictyota growth was significantly stimulated by nutrient enrichment only at elevated CO2, which led to the highest biomass ratios of Dictyota to Halimeda. Our results suggest that inorganic nutrient enrichment alone stimulates several aspects of H. opuntia physiology, but nutrient enrichment at a CO2 concentration predicted for the end of the century benefits Dictyota sp. and hinders its calcifying basibiont H. opuntia.

PeECE II - Pelagic Ecosystem CO2 Enrichment Study, Raunefjord, Bergen, Norway

The effects of CO2-induced seawater acidification on plankton communities were also addressed in a series of 3 mesocosm experiments, called the Pelagic Ecosystem CO2 Enrichment (PeECE I-III) studies, which were conducted in the Large-Scale Mesocosm Facilities of the University of Bergen, Norway in 2001, 2003 and 2005, respectively. Each experiment consisted of 9 mesocosms, in which CO2 was manipulated to initial concentrations of 190, 350 and 750 µatm in 2001 and 2003, and 350, 700 and 1050 µatm in 2005. The present dataset concerns PeECE II.