Effect of closed areas on distribution of fish and epibenthos   总被引：2，自引：1，他引：1  

Hoffmann  E.; Dolmer  P. 《ICES Journal of Marine Science》2000,57(5):1310-1314

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Quantitative tools and simultaneous actions needed for species conservation under climate change-Reply to Shoo et al. (2013)     

Luke P. Shoo  Ary A. Hoffmann  Stephen Garnett  John K. Scott  Stephen E. Williams 《Climatic change》2015,129(1-2):1-7

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Mass-cargo-affine industries and climate change     

Anja Scholten  Benno Rothstein  Roland Baumhauer 《Climatic change》2014,122(1-2):111-125

The impact of low water periods on inland navigation and companies is well known by ship-operators and companies that rely on this mode of transport but it is rarely a topic of climate impact research. As climate change might affect the frequency and intensity of low water periods, quantifying the impact of climate change on companies and the effects of possible adaptation measures is vital. In this study, we present a model for quantifying the impact of low water events on companies which rely on inland navigation and apply that model to three anonymous iron and steel companies along the River Rhine. The deviation of optimal storage, the storage level that evens out risk vs. fixed capital, is used in the model to measure the vulnerability of companies. The results show that, depending on the climate scenario, the companies might have to deal with either one or five additional days of empty storage in the near future (2021–2050) and up to nine more days by the 2071–2100 period. Seasonal analysis shows that, consistent with the change in the river discharge, the biggest deviations from optimal storage level occur in the late summer/early autumn. Analysis of adaptation options shows that companies would need to increase storage capacity by 2.5 % for the 2021–2050 period, and by 25 % by the 2071–2100 period. A reduction of ship sizes is not an adaptation option for the three companies in this study, because these companies already use relatively small vessels. This is however an efficient adaptation option for companies which employ larger vessels for transport. Another adaptation option would be to reduce the share of transportation via inland waters, but the feasibility of this option depends on the availability and cost of other modes of transport.  相似文献   

The origin of decoupled Hf-Nd isotope compositions in Eoarchean rocks from southern West Greenland   总被引：1，自引：0，他引：1  

J. Elis Hoffmann  Carsten Münker  Minik T. Rosing 《Geochimica et cosmochimica acta》2011,75(21):6610-6628

Radiogenic isotope compositions of Hf and Nd are typically coupled in Phanerozoic and Proterozoic mafic rocks due to a similar behaviour of Lu-Hf and Sm-Nd during mantle melting. Eoarchean rocks, for instance those from southern West Greenland, exhibit an apparent decoupling of Hf and Nd isotope compositions. This apparent decoupling may either indicate metamorphic disturbance or, alternatively, mirror early differentiation processes in the silicate Earth. To evaluate the issue, we performed combined measurements of Hf-Nd isotope compositions together with major and trace element concentrations for well preserved >3720 to >3800 Ma old tholeiitic metabasalts and gabbros from the ∼3700 Ma and ∼3800 Ma old terranes of the Isua Supracrustal Belt, southern West Greenland. In contrast to younger mafic rocks, calculated initial εHf-εNd values of the Isua tholeiites show similar spreads and are both near chondritic to strongly depleted (−0.7 to +6.3 and −0.8 to +4.4, respectively), also in contrast to previously reported more depleted signatures in nearby boninite-like metabasalts of the Garbenschiefer unit. An evaluation of alteration effects based on preserved major and trace element arrays reveals pristine magmatic trends and therefore the measured isotope compositions indeed in most cases characterize contrasting Eoarchean mantle sources. In accord with this view, compositions of the Isua metabasalts yield Eoarchean regression ages in Sm-Nd and Lu-Hf isochron spaces, overlapping with emplacement ages inferred from crosscutting relationships with tonalites. Lutetium-Hf systematics of the Isua metabasalts studied here, yield clear isochron relationships. For both terranes, there is some scatter in Sm-Nd space, indicating early disturbance of the Sm-Nd system close in time to the extrusion ages, possibly by seafloor alteration. Trace element compositions of the metabasalts indicate an arc setting and a strong source overprint by melt-like subduction components. It is likely, that the source overprint may have caused partial decoupling of the εHf-εNd values, due to selective addition of Nd as observed in modern subduction settings. In this case, the most radiogenic initial εNd and εHf isotope values characterize the most depleted mantle sources, and less radiogenic values would reflect increased contributions of isotopically more enriched subduction components. However, the most depleted samples still exhibit decoupled Hf-Nd compositions, making a case for the presence of even older mantle heterogeneities. A proposed superchondritic composition of the silicate Earth (SCHEM), however, cannot account for the most depleted sample compositions. Conversely, a depleted upper mantle formed by crystallization of perovskite-rich cumulates in the early Hadean may well explain these observed compositions. A literature survey reveals an overlap in initial Hf-Nd compositions between southern West Greenland TTGs and the metabasalts analyzed here. This overlap suggests a genetic relationship between these lithologies, where the TTGs may have inherited their unusual Hf-Nd compositions from mafic precursors isotopically similar in composition to the Isua tholeiites.  相似文献   

Sources of fluids and gases expelled at cold seeps offshore Georgia, eastern Black Sea   总被引：1，自引：0，他引：1  

Anja Reitz  Thomas Pape  Mark Schmidt  Florian Scholz  Giovanni Aloisi  Stephan M. Weise 《Geochimica et cosmochimica acta》2011,75(11):3250-46

Four seep sites located within an ∼20 km² area offshore Georgia (Batumi seep area, Pechori Mound, Iberia Mound, and Colkheti Seep) show characteristic differences with respect to element concentrations, and oxygen, hydrogen, strontium, and chlorine isotope signatures in pore waters, as well as impregnation of sediments with petroleum and hydrocarbon potential. All seep sites have active gas seepage, near surface authigenic carbonates and gas hydrates. Cokheti Seep, Iberia Mound, and Pechori Mound are characterized by oil-stained sediments and gas seepage decoupled from deep fluid advection and bottom water intrusion induced by gas bubble release. Pechori Mound is further characterized by deep fluid advection of lower salinity pore fluids. The Pechori Mound pore fluids are altered by mineral/water reactions at elevated temperatures (between 60 and 110 °C) indicated by heavier oxygen and lighter chlorine isotope values, distinct Li and B enrichment, and K depletion. Strontium isotope ratios indicate that fluids originate from late Oligocene strata. This finding is supported by the occurrence of hydrocarbon impregnations within the sediments. Furthermore, light hydrocarbons and high molecular weight impregnates indicate a predominant thermogenic origin for the gas and oil at Pechori Mound, Iberia Mound, and Colkheti Seep. C₁₅₊ hydrocarbons at the oil seeps are allochtonous, whereas those at the Batumi seep area are autochthonous. The presence of oleanane, an angiosperm biomarker, suggests that the hydrocarbon source rocks belong to the Maikopian Formation. In summary, all investigated seep sites show a high hydrocarbon potential and hydrocarbons of Iberia Mound, Colkheti Seep, and Pechori Mound are predominantly of thermogenic origin. However, only at the latter seep site advection of deep pore fluids is indicated.  相似文献   

Making decisions to conserve species under climate change     

Luke P. Shoo  Ary A. Hoffmann  Stephen Garnett  Robert L. Pressey  Yvette M. Williams  Martin Taylor  Lorena Falconi  Colin J. Yates  John K. Scott  Diogo Alagador  Stephen E. Williams 《Climatic change》2013,119(2):239-246

Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not be adequately addressed by conventional approaches to conservation. As a result, additional management actions are now being considered. However, there is currently limited guidance to help decision makers choose which set of actions (and in what order) is most appropriate for species that are considered to be vulnerable. Here, we provide a decision framework for the full complement of actions aimed at conserving species under climate change from ongoing conservation in existing refugia through various forms of mobility enhancement to ex situ conservation outside the natural environment. We explicitly recognize that allocation of conservation resources toward particular actions may be governed by factors such as the likelihood of success, cost and likely co-benefits to non-target species in addition to perceived vulnerability of individual species. As such, we use expert judgment of probable tradeoffs in resource allocation to inform the sequential evaluation of proposed management interventions.  相似文献   

Use of sedimentary diatoms from multiple lakes to distinguish between past changes in trophic state and climate: evidence for climate change in northern Germany during the past 5,000 years     

Mirko Dreßler  Anja Schwarz  Thomas Hübener  Sven Adler  Burkhard W. Scharf 《Journal of Paleolimnology》2011,45(2):223-241

Fossil diatoms from lake sediments have been used to infer both past trophic state and climate conditions. In Europe, climate reconstructions focused on northern and alpine regions because these areas are climatically sensitive and anthropogenic impact was low. In contrast, anthropogenic impact was often high in the central European lowlands, such as northern Germany, beginning in the Neolithic Age, ~3700 BC. Since that time, trophic state change was the main factor that affected diatom assemblages in central European lowland lakes. Therefore, it was considered difficult or impossible to identify climate changes in the region using sedimented diatoms. We used diatom assemblage changes, diatom-inferred total phosphorus concentrations and the relative abundance of planktonic diatoms from sediments of three lakes that differ in their location, size, morphology, catchment area and current trophic state to test whether we could distinguish between trophic state and climate signals over the past 5,000 years in northern Germany. In this study, changes in trophic state and climate were well differentiated. In the study lakes, relative abundance of planktonic diatoms seems to be linked to the length of lake mixing phases. Planktonic diatom abundance decreased during years with shorter mixing duration, and these shorter mixing times probably reflect colder winters. The diatom-inferred periods of short mixing phases from 1000 BC to AD 500 and from AD 1300 to 1800 coincide well with two known cooling phases in Europe and the North Atlantic region.  相似文献   

Vodyanitskii mud volcano,Sorokin trough,Black Sea: Geological characterization and quantification of gas bubble streams     

Heiko Sahling  Gerhard Bohrmann  Yuriy G. Artemov  André Bahr  Markus Brüning  Stephan A. Klapp  Ingo Klaucke  Elena Kozlova  Aneta Nikolovska  Thomas Pape  Anja Reitz  Klaus Wallmann 《Marine and Petroleum Geology》2009

Vodyanitskii mud volcano is located at a depth of about 2070 m in the Sorokin Trough, Black sea. It is a 500-m wide and 20-m high cone surrounded by a depression, which is typical of many mud volcanoes in the Black Sea. 75 kHz sidescan sonar show different generations of mud flows that include mud breccia, authigenic carbonates, and gas hydrates that were sampled by gravity coring. The fluids that flow through or erupt with the mud are enriched in chloride (up to ∼650 mmol L⁻¹ at ∼150-cm sediment depth) suggesting a deep source, which is similar to the fluids of the close-by Dvurechenskii mud volcano. Direct observation with the remotely operated vehicle Quest revealed gas bubbles emanating at two distinct sites at the crest of the mud volcano, which confirms earlier observations of bubble-induced hydroacoustic anomalies in echosounder records. The sediments at the main bubble emission site show a thermal anomaly with temperatures at ∼60 cm sediment depth that were 0.9 °C warmer than the bottom water. Chemical and isotopic analyses of the emanated gas revealed that it consisted primarily of methane (99.8%) and was of microbial origin (δD-CH₄ = −170.8‰ (SMOW), δ¹³C-CH₄ = −61.0‰ (V-PDB), δ¹³C-C₂H₆ = −44.0‰ (V-PDB)). The gas flux was estimated using the video observations of the ROV. Assuming that the flux is constant with time, about 0.9 ± 0.5 × 10⁶ mol of methane is released every year. This value is of the same order-of-magnitude as reported fluxes of dissolved methane released with pore water at other mud volcanoes. This suggests that bubble emanation is a significant pathway transporting methane from the sediments into the water column.  相似文献   

The stabilisation of wet sediment cores by means of a polyethylene glycol/freeze-drying treatment for display and permanent storage     

Per Hoffmann  Jürgen Pätzold 《Geo-Marine Letters》2001,21(4):245-252

A reversible method is presented to transform waterlogged sediment cores into dry and stable specimens which can go on exhibition or into permanent storage, needing no special precautions. Wet sediment core segments are bath-impregnated with polyethylene glycol of molecular weight 3,350 (PEG 3,350) dissolved in water. The samples are then subjected to a freeze-drying process, during which the PEG forms a stabilising and bonding porous network structure in the capillary system of the sediment. Standard sediment cores at least 1 m long become strong enough to stand upright. Sediment types ranging from muddy deep-sea sediments to very coarse littoral Halimeda sand were successfully stabilised. For standard cores of 10-cm diameters split length-wise, impregnation times vary from 2 weeks for coarse sand to 6–10 weeks for more compacted sediments. With regard to the stability of the samples and the visual clarity of detail, best results were obtained by impregnation with 25 to 60% solutions of PEG 3,350, coarse sediments needing more PEG than finer ones. Colour changes are systematic – the processed samples are lighter in appearance and the contrasts are enhanced, but there is no serious shift in colour tones. The PEG can easily be re-dissolved and washed out of the sediments. Display specimens can thus be made available for research again.  相似文献   

Illumina sequencing for the identification of filamentous bulking and foaming bacteria in industrial activated sludge plants     

T. Dunkel  E. L. de León Gallegos  C. Bock  A. Lange  D. Hoffmann  J. Boenigk  M. Denecke 《International Journal of Environmental Science and Technology》2018,15(6):1139-1158

In this study, Illumina sequencing was used for the identification of bulking and foaming bacteria in industrial wastewater treatment plants. The reliable identification of bulking and foaming bacteria represents the first step in developing effective and specific control strategies to avoid disturbances in activated sludge systems. Illumina sequencing revealed 432 16S rRNA operational taxonomic units, representing phylotypes and including 21 bulking and foaming bacteria in the two investigated industrial wastewater treatment plants. Foaming represents the most severe problem in the cascade biology system. Up to 22.5% of all sequencing reads are bulking and foaming bacteria, including Chryseobacterium, Candidatus Microthrix parvicella and Gordonia sp. as the dominant bulking and foaming bacteria which are known for foam formation. Moreover, Illumina sequencing revealed an increase in Candidatus Microthrix parvicella and Gordonia sp. reads from activated sludge to foam and scum samples, indicating a preferred flotation and/or growth advantages in the foam and scum layers. Analyses of the taxonomic assignment and distribution showed that the phylum Actinobacteria is the most dominant phylum, underlining the key role of Actinobacteria in bulking and foaming. Multivariate data analysis was applied, revealing that the dominant bulking and foaming bacteria are positively correlated with the sludge age and influent flow and negatively correlated with the dissolved oxygen level and the temperature. In terms of developing a specific control strategy, the positive linear relationships to the fatty acid and surfactant sludge loadings are highlighted and the removal of lipid compounds from the wastewater influent could avoid an overgrowth of bulking and foaming bacteria.  相似文献