ALBERT

Beschreibung: We discuss the results of measurements in the region of Cape Baranov (the Severnaya Zemlya archipelago) of the set of physicochemical characteristics of atmospheric aerosol: aerosol optical depth, aerosol and black carbon concentrations, elemental and ion compositions of aerosol, organic and elemental carbon contents in aerosol, as well as the isotopic composition of carbon in the aerosol and snow samples. It is shown that the average values of most aerosol characteristics, measured in April–June 2018, are a little lower than in the Arctic settlement Barentsburg (Spitsbergen archipelago) and several-fold smaller than in the south of Western Siberia in the same period.

Beschreibung: Die 72. Reise der FS Poseidon fand zwischen dem 9. und 13. März 1981 im Skagerrak statt.

Beschreibung: As coastal areas become increasingly vulnerable to climate change, the study of nearshore sediment textures along the littoral cell of the Medjerda delta in the Gulf of Tunis, southern Mediterranean coast can provide valuable information (i) on the origin (continental or marine) of the sediment, (ii) its transport direction, and (iii) constitutes an important tool in the assessment of coastal sensitivity. A total of 120 sediments samples underwent grain size analysis and statistic parameters have been calculated. These allowed the identification of five different Sedimentary Types (ST). Accordingly, using grain size indexes (i.e. Mz, SKI and Ku), Sediment Trend Analysis (STA) modeling tools were applied to define the seasonal sediment transport pathways throughout the nearshore of the Medjerda sedimentary cell. Results show that grain size distribution (GSD) and STA model pathways are determined by cross-shore geomorphology, location of the sediment-cell, seasonal incident wave and local terrestrial supply. The appearance in an atypical seabed location of the finer (Mo = 0.1 mm) and the coarser STs (Mo = 0.8 mm) can be indicative of human influence since the coarser particles are usually retained by dam structures. Moreover, the bimodality and the increased distribution of mud are also related to the seasonal incident wave winnowing of the historic deltaic plain submerged by the relative rise in sea level. The evolution of the sediment pattern towards a greater proportion of very fine grains indicates a deficit of sediment supply, particularly of the coarser grains, and demonstrates the coastal vulnerability of the Gulf of Tunis due to anthropic effects.

Beschreibung: Hydrothermal fluids on the modern seafloor are important carriers of base and precious metals in a wide range of volcanic and tectonic settings. The concentrations and distribution, especially of gold and silver, in associated seafloor massive sulfide (SMS) deposits are strongly influenced by variable source rocks, fluid chemistry, and precipitation mechanisms. Compositional data of 130 SMS deposits around the world show a large range of gold and silver grades, in part reflecting strong buffering of the hydrothermal fluids by their host rocks. Geochemical reaction-path modeling shows that in most cases the investigated hydrothermal fluids are undersaturated with gold and silver, and solubilities can be orders of magnitude higher than the Au and Ag concentrations measured in the corresponding fluids. Precipitation of gold during conductive cooling of mid-ocean ridge black smoker (MOR) fluids occurs at low temperatures but can be very rapid, with 〉 90% of the gold deposited in the first 25 °C of cooling below ~ 150 °C. The result is a Zn–Au polymetallic assemblage with Au and Ag deposited at the same time together with Pb and sulfosalts. In ultramafic-dominated (UM) systems, the strongly reduced hydrothermal fluids promote the deposition of gold at higher temperatures and explain the correlation between gold and copper in these deposits. In this case, the lower stability of the AuHS° complex at low ƒO2 (buffered by fayalite, magnetite, and quartz) results in gold deposition at 〉 250 °C with early bornite and chalcopyrite and before sphalerite and silver, producing a high-temperature Cu–Au assemblage. In sediment-hosted (SED) systems, the much higher pH stabilizes Au(HS)2− and keeps gold in solution to very low temperatures, after the precipitation of chalcopyrite, sphalerite, and galena, resulting in Au-poor polymetallic sulfides and very late-stage deposition of gold, commonly with amorphous silica. In arc-related (ARC) systems, gold deposition occurs at somewhat higher temperatures than in the MOR case, in part because the fluids start with higher gold concentrations. This can be explained by probable direct magmatic contributions, and the high ƒO2 of the fluids, which promotes the solubility of gold at the source. During cooling, gold precipitates at about 160 °C with sphalerite, tennantite, silver, and galena, resulting in an Au-rich polymetallic sulfide assemblage. The mixing of hydrothermal fluids with seawater generally causes oxidation and eventually a decrease in the pH at a mixing ratio of 1:1, causing an initial increase in the solubility of gold and silver. This can delay gold deposition from aqueous species to very low temperatures. These complex systematics make prediction of Au and Ag grades difficult. However, important new data are coming to light on the actual concentrations of the precious metals in hydrothermal fluids. In particular, the input of magmatic volatiles and leaching of pre-existing gold can lead to significant increases in the Au and Ag concentrations of the venting fluids and earlier deposition. In several cases, it appears that at least part of the gold load is present as nanoparticles in suspension, allowing bulk gold concentrations that may be far in excess of liquid saturation. Boiling at the seafloor is now widely observed, even at great water depths close to the critical point of seawater. Model calculations of phase separation during boiling show the competing effects on gold solubility of H2, H2S, and CO2 partitioning into the vapor, which can result in highly variable gold-to-base metal ratios in the deposits. Flashing of the vent fluids into steam at high temperatures is also commonly observed and can lead to spectacular Au grades, with a strong Cu–Au association in the deepest and hottest vents.

Beschreibung: The order Botryosphaeriales includes many latent fungal pathogens with a wide range of woody hosts. The taxonomy of these pathogens has been difficult due to the use of poorly informing markers in phylogenetic analyses and the lack of good morphological characters. Many genera and families in this order have not yet been systematically studied in different hosts and from different regions. In this study, a total of 29 fungal strains from the Aplosporellaceae and Botryosphaeriaceae were isolated from branches or twigs with symptoms of canker and dieback disease in Mount Yudu of China. Morphology and multigene analyses (ITS, LSU and TEF1-α) indicated five distinct lineages, including Aplosporella javeedii, Botryosphaeria dothidea, Diplodia quercicola sp. nov., Phaeobotryon aplospora sp. nov. and Phaeobotryon rhois. Diplodia quercicola is characterized by multiloculate conidiomata, producing oblong to cylindrical, thick-walled, hyaline, aseptate conidia. Phaeobotryon aplospora is characterized by pulvinate, multiloculate conidiomata, producing ellipsoid to oblong, brown, aseptate conidia. The new species differ from related species phylogenetically and ecologically and in morphological features.

Beschreibung: Three large plastic enclosures (3-4 m3) were anchored in the outer harbour of Helgoland (German Bight) and filled with natural seawater which was filtered free of algae. The enclosed water bodies were enriched with inorganic nutrients and inoculated with the diatom Thalassiosira rotula. During the growth of the algae diurnal changes in concentration of dissolved free amino acids (DFAA) occurred. The periodic concentration changes of individual amino acids with a low carbon to nitrogen ratio showed significant interrelationships with the partly synchronous devisions of the diatoms. From the exponential to the stationary phase the carbon to nitrogen ratio of DFAA shifted to higher values pointing at an adaptation of the organisms to the decreasing inorganic nitrogen source. During the bloom amino acids relatively rich in nitrogen were mainly excreted but by the end of the growth amino acids with a higher carbon content predominated. At phases of high photosynthetic activity the organisms probably reduced the high osmotic pressure by exudation of DFAA.

Beschreibung: Copepods are an important link in the marine food web, and, in particular, serve as food for fish larvae. Schizopera elatensis, a marine harpacticoid copepod, was reared in the laboratory, and the effect of various environmental factors, i.e., diet, temperature, salinity and height of water column on its growth was determined. Schizopera elatensis multiplies at a wide range of salinities, 10‰ to 70‰, and temperatures, from at least 18° C to an upper limit of 36° C, with an optimum of 25° C, and grows in high densities (300-400 individuals per ml): the lower the water column, the higher the density. The prospective use of S. elatensis as a live food organism in mariculture is discussed.

Beschreibung: The importance of bacteria in the feeding of marine bivalves has been demonstrated by several authors. Some examples of good growth of molluscs were noted on a bacterial diet only. But, while the intense filtration of bacteria by molluscs has been observed, the exact role of bacteria in the nutrition of bivalves was not completely known. The filtered particles were sometimes eliminated as pseudofaeces, without any intestinal transit. On the other hand, live cells could also pass through the gut without being degested. To study in detail the fate of bacterial cells distributed as food to young bivalves, we used a new method which combines histology and scanning electron microscopy. This made it possible to observe, on serial histological sections of whole animals, the gut content and the condition of the ingested cells at the different levels of the intestinal tract. The ingestion and digestion by young mussels (Mytilus edulis) of some marine bacterial strains belonging to different taxonomic groups were studied by this method. Thus, partially digested bacterial cells were observed in the stomach, when the hind gut contained undamaged cells, three hours after food distribution. The results obtained for all the strains we tested are presented and discussed in this paper.

Beschreibung: Eutrophication by sewage effluent has led to the development of extensive mats of green algae over much of the former open mudlands of Langstone Harbour on the south coast of Britain. The presence of the mal reduces the biomass and diversity of the mud-dwelling infauna but a great increase in the number and biomass of epibenthic animals (primarily Hydrobia ulvae Pennant) produces a total biomass almost twice that of open mudlands. Although the common invertebrates are favoured prey for many estuarine birds these algal areas are avoided by the dense aggregation of waders and wildfowl.

Beschreibung: From April to September 1978 benthos and plankton samples were taken at three different sites in the Schlei fjord (German Baltic coast) with different salinity (ca. 15, 10 and below 5‰). Abundances of benthos and plankton taxa were compared with abundances of the taxa occurring in the guts of Pomatoschistus microps and P. minutus, caught at the same places at the same time. Main food were calanoids, oligochaetes and harpacticoids. Calculations showed that young gobies most probably regulate the population of harpacticoids to a large extent by grazing.