Polycyclic aromatic hydrocarbons in water and sediment of the Baltic Sea   总被引：10，自引：0，他引：10  

G. Witt 《Marine pollution bulletin》1995,31(4-12)

Between 1992 and 1994, the distribution of 15 polycyclic aromatic hydrocarbons (PAHs) was investigated in seawater and surface sediments of the Baltic Sea. The analysis of PAHs in seawater is very difficult due to the low concentration. High separation capability is required. A method for analysing very low concentrations of PAHs is presented. The method is based on the high-performance liquid chromatography (HPLC) with fluorescence detection. The concentrations of PAHs in seawater are discussed in relation to water depth. A seasonal variation of PAHs in seawater was observed, with lowest concentrations occurring in summer and generally higher concentrations occurring in November. According to the regional distribution, elevated concentrations of PAHs were found in coastal regions of the Baltic Sea. The regional distribution of PAHs in surface sediments of the Belt Sea and the Arkona Basin were also investigated. The relationship between the content of PAHs and the percentage of total organic carbon in sediments is discussed.  相似文献   

Quaternary sedimentation and active faulting along the Ecuadorian shelf: preliminary results of the ATACAMES Cruise (2012)     

F. Michaud  J. N. Proust  J. Y. Collot  J. F. Lebrun  C. Witt  G. Ratzov  H. Pouderoux  C. Martillo  M. J. Hernández  G. Loayza  L. Penafiel  L. Schenini  A. Dano  M. Gonzalez  D. Barba  L. De Min  G. Ponce  A. Urresta  M. Calderon 《Marine Geophysical Researches》2015,36(1):81-98

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How do Local People Value Rural Waterways? A Study in the Upper Catchments of South East Queensland’s Rivers     

Katherine Witt  Helen Ross  Sylvie Shaw  Natalie Jones  David Rissik  Breanna Pinner 《社会与自然资源》2019,32(6):638-656

In Integrated Catchment (or Watershed) Management, the impacts of upstream conditions and actions on downstream environments and people is a key issue. Knowing upstream people’s values towards waterways is, therefore, important for community engagement and the development of publicly acceptable management approaches. This qualitative study applies Kellert’s framework of relational values to explore the types and diversity of people’s values towards the upper catchments of South East Queensland, Australia, and tests the “universality” of Kellert’s framework. We found the full range of values identified by Kellert with some variations and elaborations in content. People living, working, and enjoying recreation in the upper catchments have affection for their local waterways and a moral inclination to protect them. This extends our understanding of how people value these waterways, which is more often depicted in terms of utilitarian and economic value. The findings provide managers with new opportunities for engaging with local communities and waterway users.  相似文献   

The Consequences of the Oder Flood in 1997 on the Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in the Oder River Estuary     

Gesine Witt  Herbert Siegel 《Marine pollution bulletin》2000,40(12):1124-1131

Changes in the levels and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) as a consequence of the Oder flood in the summer of 1997 were investigated in surface water samples and fluffy layer material from the Oder Lagoon and the Pomeranian Bight. The measurements of the contaminants were complemented by satellite data to describe the spreading of the Oder flood discharge including the distribution of the particulate material. During the flood elevated levels of PAHs were discussed in the surface water and fluffy layer material of the Oder River Estuary in comparison to the average values in this region. These increased concentrations were attributed to flooding of municipal and industrial waste disposal areas in the drainage area of the Oder River. The meteorological conditions during the sampling period were characterized by predominant easterly winds, which guided the river plume along the German coast into the Arkona Sea, as verified by satellite observations. The highest concentrations of PAHs were observed near the mouth of the Swina and along the main direction of the river plume. Elevated concentrations of PAHs were also found in fluffy layer samples taken from the Oder Lagoon in late August. As derived from satellite data the eastern and the western parts of the lagoon differed in their SPM load during the entire flood period. The eastern part was covered by Oder water, while the western part contained a mixture of Oder Lagoon water. The highest concentrations of PAHs were not observed in the western part with the highest suspended matter values, but in the eastern part where the flood water entered the lagoon. Despite the significantly increased PAH levels measured during the flood, all measured concentrations were below the values that are considered to pose a risk to the ecosystem.  相似文献   

Palynological evidence for climatic and oceanic variability off NW Africa during the late Holocene     

Ilham Bouimetarhan  Lydie Dupont  Enno Schefuß  Gesine Mollenhauer  Stefan Mulitza  Karin Zonneveld   《Quaternary Research》2009,72(2):188-197

Pollen and organic-walled dinoflagellate cyst assemblages from core GeoB 9503-5 retrieved from the mud-belt ( 50 m water depth) off the Senegal River mouth have been analyzed to reconstruct short-term palaeoceanographic and palaeoenvironmental changes in subtropical NW Africa during the time interval from ca. 4200 to 1200 cal yr BP. Our study emphasizes significant coeval changes in continental and oceanic environments in and off Senegal and shows that initial dry conditions were followed by a strong and rapid increase in humidity between ca. 2900 and 2500 cal yr BP. After ca. 2500 cal yr BP, the environment slowly became drier again as indicated by slight increases in Sahelian savannah and desert elements in the pollen record. Around ca. 2200 cal yr BP, this relatively dry period ended with periodic pulses of high terrigenous contributions and strong fluctuations in fern spore and river plume dinoflagellate cyst percentages as well as in the fluxes of pollen, dinoflagellate cysts, fresh-water algae and plant cuticles, suggesting “episodic flash flood” events of the Senegal River. The driest phase developed after about 2100 cal yr BP.  相似文献   

Holocene sea-surface temperature variability in the Chilean fjord region     

Magaly Caniupán  Frank Lamy  Carina B. Lange  Jérôme Kaiser  Rolf Kilian  Helge W. Arz  Tania León  Gesine Mollenhauer  Susana Sandoval  Ricardo De Pol-Holz  Silvio Pantoja  Julia Wellner  Ralf Tiedemann 《Quaternary Research》2014

Here we provide three new Holocene (11–0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50–53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past ~ 0.6 cal ka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During the mid-Holocene, pronounced short-term variations of up to 2.5°C and a cooling centered at ~ 5 cal ka BP, which coincides with the first Neoglacial glacier advance in the Southern Andes, are recorded. The latest Holocene is characterized by two pronounced cold events centered at ~ 0.6 and 0.25 cal ka BP, i.e., during the Little Ice Age. These cold events have lower amplitudes in the offshore records, suggesting an amplification of the SST signal in the inner fjords.  相似文献   

Source component mixing controls the variability in Cu and Au endowment along the strike of the Eastern Andean Cordillera in Peru     

Thomas?AngererEmail authorView author&#;s OrcID profile  Anthony?I.?S.?Kemp  Steffen?G.?Hagemann  Walter?K.?Witt  Jo?o?O.?Santos  Christian?Schindler  Carlos?Villanes 《Contributions to Mineralogy and Petrology》2018,173(5):36

Mississippian arc magmatic suites of the Au-rich Pataz and Cu-dominated Montañitas regions in Peru reveal distinct modes of magmatic-hydrothermal petro- and metallogenesis. The distinction is remarkable due to their broad contemporaneity (336–322 Ma), arc-parallel position, and close distance (<?50 km) to each other. In both arc regions, petrography, geochemistry, and the tectonic setting of magmatic suites suggest a rapid switch from syn-collisional/compressional to post-collisional/extensional (with ‘A₂-type’ signature) emplacement regime. Rocks of the Au-rich Pataz region originate from mixed sources with a contribution from the mantle (εHf?>?0 and δ¹⁸O of ~?5.3‰) and assimilated old crust (variously low εHf and δ¹⁸O >?5.3‰). The ultimate source of Au in the mineralised Pataz batholith was oxidised (fO₂ at FMQ buffer; based on zircon trace chemistry) and alkali-, LILE- and HFSE-enriched, most likely represented by the metasomatised mantle. The syn-extensional emplacement of the relatively reduced (ΔFMQ?<?0), but unmineralised, A₂-type suite involved assimilation of reduced crust. Associated, reduced, magmatic-hydrothermal fluids infiltrated the Au-bearing batholith suite and effectively mobilised and transported and concentrated Au. In the Montañitas region, rocks are oxidised (ΔFMQ?>?0) and dominantly mantle derived without significant incorporation of crustal material. Samples from the Cu-mineralised suites indicate the additional contribution of a δ¹⁸O <?5.3‰ source, potentially melted layer-2 gabbro. In addition, the elevated whole-rock La/Yb and Sr/Y ratios are compatible with minor addition of slab-derived material, which may have enhanced Cu endowment in this region. Late-magmatic, oxidised fluids derived from the younger A₂-type suite controlled Cu mobilisation and concentration, while Au behaved largely refractory. In general terms, it is postulated that source mixing in continental arcs is a first-order control of contrasting Cu and Au endowment and that sequential intrusion processes facilitate late-magmatic-hydrothermal mobilisation and concentration of specific metal assemblages.  相似文献   

On the state of ionization of the local interstellar medium     

P. W. Blum  S. Grzędzielski  N. Witt 《Astrophysics and Space Science》1980,70(2):513-522

The abundance ratio of neutral hydrogen to helium, as deduced from interplanetary observations of Lyman-alpha and He 584 Å radiation by Mariner 10, is significantly lower than the cosmic abundance ratio of these elements, thus showing that the local interstellar medium (LISM) is partly ionized. The effect of various sources of ionization — especially electron impact and EUV photon flux — on hydrogen and helium is discussed. It is shown that the observational data on the temperature of the LISM, on the diffuse EUV flux and on the neutral and electron densities in the nearby interstellar medium (NISM) are not all compatible. However, if the diffuse EUV flux below 912 Å as deduced from the preliminary analysis of Voyager observations is not representative, then it is easy to reconcile all observations. In this case an important source of ionization of the LISM would be electron impact, yielding an ionization degree of about 50% for the hydrogen component.  相似文献   

On the validity of a model for the reversals of the Earth's magnetic field     

A. Witt  J. Kurths  F. Krause  K. Fischer 《地球物理与天体物理流体动力学》2013,107(1-4):79-91

Abstract

We have used techniques of nonlinear dynamics to compare a special model for the reversals of the Earth's magnetic field with the observational data. Although this model is rather simple, there is no essential difference to the data by means of well-known characteristics, such as correlation function and probability distribution. Applying methods of symbolic dynamics we have found that the considered model is not able to describe the dynamical properties of the observed process. These significant differences are expressed by algorithmic complexity and Renyi information.  相似文献   

Ecotoxicity assessment of natural attenuation effects at a historical dumping site in the western Baltic Sea     

Leipe T  Kersten M  Heise S  Pohl C  Witt G  Liehr G  Zettler M  Tauber F 《Marine pollution bulletin》2005,50(4):446-459

During the late 1950s and early 1960s of the past century, industrial waste material highly enriched in various contaminants (heavy metals, PAHs) was dumped in the inner Mecklenburg Bay, western Baltic Sea. Large-scale shifts in the spatial distribution of heavy metals in surface sediments were mapped by geochemical monitoring in the mid-1980s and 12 years later in 1997. A further study in 2001 was designed to investigate the small-scale spatial distribution of contaminants inside, on top of, and around the historical dumping ground and to examine possible effects to benthic organisms (Arctica islandica, microbiological toxicity tests). The site is located within an area characterized by a discontinuous deposition of fine sediments, but net sedimentation rate of about 3mm/y led ultimately to a gradual coverage of the dumped material. During the first decades after the dumping, about half of the originally dumped material was already spread over the surrounding area as a result of sediment dynamics and re-suspension processes. Recent sediments of the historical dump site are still significantly enriched in heavy metals and PAHs. Microbiological toxicity test results were positive, though uptake of contaminants in mussels was found to deviate only slightly from that of a non-contaminated reference station due to a gradual dilution and decrease in bioavailability of the contaminants.  相似文献