ALBERT

Beschreibung: In this work, the popular CAS assay for siderophore detection, based on the utilization of chrome azurol S, was redesigned and optimized to produce a new, fast, non-toxic, and easy method to determine a wide variety of microorganisms capable of siderophore production on a solid medium. Furthermore, this specific bioassay allows for the identification of more than one single siderophore-producing microorganism at the same time, using an overlay technique in which a modified CAS medium is cast upon culture agar plates (thus its name “O-CAS”, for overlaid CAS). Detection was optimized through adjustments to the medium's composition and a quantifying strategy. Specificity of the bioassay was tested on microorganisms known for siderophore production. As a result, a total of 48 microorganisms were isolated from three different types of samples (fresh water, salt water, and alkaline soil), of which 36 were determined as siderophore producers. The compounds identified through this method belonged to both hydroxamate and catechol-types, previously reported to cause color change of the CAS medium from blue to orange and purple, respectively. Some isolated microorganisms, however, caused a color change that differed from previous descriptions.

Beschreibung: Energy is an essential ingredient of socio-economic development and economic growth. Renewable energy sources like wind energy is indigenous and can help in reducing the dependency on fossil fuels. Wind is the indirect form of solar energy and is always being replenished by the sun. Wind is caused by differential heating of the earth's surface by the sun. It has been estimated that roughly 10 million MW of energy are continuously available in the earth's wind. Wind energy provides a variable and environmental friendly option and national energy security at a time when decreasing global reserves of fossil fuels threatens the long-term sustainability of global economy. This paper reviews the wind resources assessment models, site selection models and aerodynamic models including wake effect. The different existing performance and reliability evaluation models, various problems related to wind turbine components (blade, gearbox, generator and transformer) and grid for wind energy system have been discussed. This paper also reviews different techniques and loads for design, control systems and economics of wind energy conversion system.

Beschreibung: The calcium isotopic compositions (δ44Ca) of 30 high-purity nannofossil ooze and chalk and 7 pore fluid samples from ODP Site 807A (Ontong Java Plateau) are used in conjunction with numerical models to determine the equilibrium calcium isotope fractionation factor (αs−f) between calcite and dissolved Ca2+ and the rates of post-depositional recrystallization in deep sea carbonate ooze. The value of αs−f at equilibrium in the marine sedimentary section is 1.0000 ± 0.0001, which is significantly different from the value (0.9987 ± 0.0002) found in laboratory experiments of calcite precipitation and in the formation of biogenic calcite in the surface ocean. We hypothesize that this fractionation factor is relevant to calcite precipitation in any system at equilibrium and that this equilibrium fractionation factor has implications for the mechanisms responsible for Ca isotope fractionation during calcite precipitation. We describe a steady state model that offers a unified framework for explaining Ca isotope fractionation across the observed precipitation rate range of ∼14 orders of magnitude. The model attributes Ca isotope fractionation to the relative balance between the attachment and detachment fluxes at the calcite crystal surface. This model represents our hypothesis for the mechanism responsible for isotope fractionation during calcite precipitation. The Ca isotope data provide evidence that the bulk rate of calcite recrystallization in freshly-deposited carbonate ooze is 30–40%/Myr, and decreases with age to about 2%/Myr in 2–3 million year old sediment. The recrystallization rates determined from Ca isotopes for Pleistocene sediments are higher than those previously inferred from pore fluid Sr concentration and are consistent with rates derived for Late Pleistocene siliciclastic sediments using uranium isotopes. Combining our results for the equilibrium fractionation factor and recrystallization rates, we evaluate the effect of diagenesis on the Ca isotopic composition of marine carbonates at Site 807A. Since calcite precipitation rates in the sedimentary column are many orders of magnitude slower than laboratory experiments and the pore fluids are only slightly oversaturated with respect to calcite, the isotopic composition of diagenetic calcite is likely to reflect equilibrium precipitation. Accordingly, diagenesis produces a maximum shift in δ44Ca of +0.15‰ for Site 807A sediments but will have a larger impact where sedimentation rates are low, seawater circulates through the sediment pile, or there are prolonged depositional hiatuses.

Beschreibung: Due to the high mortality rates and poor growth generally observed in Octopus vulgaris paralarval rearing experiments, it was decided to organize a working group in order to formulate recommendations to tackle this problem. Over a dozen scientists representing the most active current research groups related to this subject attended the meeting in Vigo, Spain, in November 2005. The aim of this working group was to determine the bottlenecks that prevent success in paralarval rearing, define the most appropriate rearing conditions, and identify required future research. This paper describes rearing techniques for the O. vulgaris paralarvae used by the different research participant teams, with regard to tank systems, feeding environment, and diets (Artemia, crustacean zoeae, sandeel flakes, copepods, etc.). Additionally, it includes other related themes such as the culture of Artemia and copepods, organisms that are commonly used in paralarval rearing. When embarking on O. vulgaris rearing it is advised to use prey rich in DHA (docosaenoic acid, 22:6n-3) and EPA (eicosapentaenoic acid, 20:5n-3), and with high DHA/EPA ratio. Such prey could be enriched Artemia, accompanied or not by crustacean zoeae or any microdiet. It is also recommended that, in future studies, values of growth and survival rates are recorded at the beginning of the benthic phase, in order to compare them to successful previous studies. Dry weight and DHA/EPA ratio of paralarvae may also be good criteria to define paralarval viability and evaluate success of the rearing system. It is further concluded that the nutritional aspect is the most important factor influencing larval mortality. Certain lipids (phospholipids, cholesterol, and polyunsaturated fatty acids), amino acids (lysine, leucine and arginine), and essential elements (e.g. copper) play a relevant role in the larval nutrition. It is believed that the PUFA content, especially DHA and EPA, constitutes one of the basic nutritional requirements. Regarding new research lines, no standardized system for paralarval rearing exists, and it is essential to make progress on this issue. Research on nutritional requirements is considered an area of highest priority, especially the development of a specific enrichment for Artemia, the search for alternative live preys, and the development of suitable formulated diets.

Beschreibung: Paralarvae of the family Gonatidae were sampled in the Gulf of Alaska during spring 2001–2003. Taxonomic characters were determined to allow identification of the specimens to species. The dorsal head chromatophore pattern (DHCP) was the most robust character and allowed identification to species for the first time without requiring the removal and examination of the radula. Six different DHCPs were found among the six species in the study area. The 1140 specimens collected consisted of the following six species: Berryteuthis anonychus (759), Berryteuthis magister (71), Gonatopsis borealis (155), Gonatus kamtschaticus (1), Gonatus madokai (4) and Gonatus onyx (143). The specimens had a size range of 3.0–20.63 mm dorsal mantle length with the majority of specimens smaller than 10 mm. All species showed an increasing trend in abundance from the shelf (0–200 m) to the slope (200–1000 m) to the basin (〉1000 m) except G. onyx in 2001 and 2002. Wide variation in distribution and abundance was found for the four most abundant species; however, in general, B. anonychus was most abundant and widely distributed, followed by Gonatopis borealis, Gonatus onyx and B. magister.

Beschreibung: Dissolved organic carbon (DOC) in the oceans is one of the largest dynamic carbon reservoirs on earth. The composition and fate of this carbon reservoir is of great interest to earth scientists, atmospheric scientists, and biologists who study global biogeochemical cycles and global warming. Current techniques for the extraction and purification of dissolved organic matter (DOM) from seawater for research purposes recover at best only 30 wt% of DOC. A new technique for the recovery of DOM from seawater has been developed by combining electrodialysis and reverse osmosis. Here we present shipboard results and laboratory work to show the feasibility of our technique. DOC recoveries exceeding 60% and even exceeding 90% for one seawater sample have been found. Analysis of samples recovered using this technique will yield new insights into the cycling of DOC in the oceans.

Beschreibung: Zoning patterns of An content and Fe, Mg and Sr concentrations in plagioclase phenocrysts in andesites from Parinacota Volcano (N. Chile) reflect alternating recharge events with two chemically distinct mafic magmas. These magmas are characterized by low and high Sr contents, similar to two recent mafic flank eruptions. One end-member basaltic andesite shows large Sr enrichment and Heavy Rare Earth depletions and thus equilibrated with lower-crustal rocks at depth where plagioclase (high Sr) is unstable, and garnet (high HREE, Y) is stable. A second end-member magma is lower in Sr, Ba contents and has REE patterns typical for parent magmas elsewhere in the Central Andes. The number of recorded recharge events increases after a catastrophic sector collapse and during the subsequent rebuilding of the stratocone. Variations of An, Fe and Mg contents and morphology of zones suggest also changes in water pressure, including decompression under water under-saturated and water-saturated conditions. Evidence for decompression is more present in post-collapse samples, suggesting that the change in the volcano dynamics involves changes in magma chamber location. This shows the importance of the cone collapse event in the volcano's magmatic evolution. We propose that both end-members are only seen at the surface of Parinacota Volcano because of the particular dynamics of this volcanic system and that similar processes might occur in other volcanic centres of the Central Volcanic Zone.

Beschreibung: There are various similarities and differences in zooplankton processes between Arctic Ocean (AO) and Southern Ocean (SO) polynyas, many of which are due to fundamental differences in their respective ecosystem properties. The composition of zooplankton communities in AO and SO polynyas is largely dependent upon advection from local, ice-covered waters, with little evidence of an endemic, polynya zooplankton fauna. While copepods are common in both systems, a major difference is the predominance of euphausiids in the SO and appendicularian tunicates in the AO. The same genera of small copepods occur in both the AO and SO and appear to derive little benefit from the higher primary productivity and extended growing season of polynyas. In contrast, larger calanoid copepods appear to derive recruitment and life cycle benefits from the diatom production and heat in polynyas, with higher egg production rates and shorter generation times. Most large calanoid copepods overwinter in diapause in AO polynyas, while some proportion of SO populations remain in surface waters. Grazing impact by copepods in AO polynyas accounts for about 20% of primary productivity d−1, with appendicularian tunicates accounting for another 20% d−1. The few estimates of community impact in the SO are variable. In both regions, individual zooplankton feeding rates are high and equivalent to boreal ocean values; thus, grazing impact depends primarily on the biomass of zooplankton and phytoplankton. SO zooplankton contribute to the vertical particulate flux through faecal pellets from euphausiids, copepods and pteropods, while the contribution in AO polynyas is primarily through appendicularian tunicate faecal pellets and shed houses and copepod faeces. Maximum pellet flux in both the AO and SO occurs at times of high biomass of diatoms. The primary benefits of polar polynyas to zooplankton processes results from the greater production of diatoms and extended productive period, with few differences in individual daily rations or food web transfer efficiencies relative to temperate and boreal systems.