Vertical migration of radionuclides in undisturbed grassland soils

Literature data on numerical values obtained for the parameters of the two most popular models for simulating the migration of radionuclides in undisturbed soils have been compiled and evaluated statistically. Due to restrictions on the applicability of compartmental models, the convection–dispersion equation and its parameter values should be preferred. For radiocaesium, recommended values are derived for its effective convection velocity and dispersion coefficient. Data deficiencies still exist for radionuclides other than caesium and for soils of non-temperate environments.     

Eco-labelling of wild-caught seafood products

Several eco-labels for wild-caught seafood have been developed during the last decade. This article describes and analyses the criteria applied by four different eco-labelling schemes for seafood products from capture fisheries, and discusses the criteria in terms of environmental impacts, based on the ISO 14040 standard for life cycle assessment.It is concluded that the most widespread eco-label, the Marine Stewardship Council (MSC), mainly addresses the fishing stage, in particular the overexploitation of marine resources. LCA studies confirm that the fishing stage represents the most significant environmental burden, but energy consumption and emissions of anti-fouling agents at the fishing or harvesting stage contribute with significant impacts that are not being addressed by international labelling initiatives for wild-caught seafood.LCA studies show that significant environmental impacts are related to the life cycle stages after landing. This includes fish processing, transport, cooling and packaging (especially for highly processed seafood products). Hence, another challenge would be to include criteria related to the post-landing consumption of energy, certain materials and chemicals, waste handling and wastewater emissions. Minimizing product losses throughout the product chain would also be an important area for future criteria in order to avoid fishing at high environmental costs only to produce something that is later wasted.The analysis shows that the Swedish KRAV is the only one that currently addresses a range of issues that include energy and chemicals in the whole life cycle of the products. International initiatives such as MSC cover fish products from many parts of the world emphasizing ‘overexploitation of fish resources’. It is recommended, however, that international initiatives such as MSC develop criteria related to energy use and chemicals – at least at the fishing stage. Over time, other life cycle stages could be addressed as well to the extent that this is manageable.     

Fossil bog soils (‘<Emphasis Type="Italic">dwog</Emphasis> horizons’) and their relation to Holocene coastal changes in the Jade Weser region,southern North Sea,Germany

After the deceleration of the postglacial marine transgression, the German North Sea coast was subject to deposition of a complex pattern of subtidal to terrestrial facies. This study aims at reconstructing these facies changes in the ‘Land Wursten’ region (Lower Saxony) by focussing on so-called dwog horizons (incipient soil horizons of the pre-engineered salt marshes). We explore their implications for relative sea-level reconstructions and their indication for early settlement activities. Archive drilling data (1960, provided by the ‘Landesamt für Bergbau, Energie und Geologie’) were analysed to create five high-resolution stratigraphic cross sections. Three new drilling records were subjected to sedimentological and microfaunal investigations and interpreted to verify and calibrate the archive data. Two dwog horizons were found and ¹⁴C-AMS dated. We found basal salt marsh deposits inundated by a high-energy event and covered by tidal flat sediments. The thick tidal flat unit is again overlain by salt marsh deposits indicating the transition from a shallow marine to a terrestrial environment where dwogs were developed and covered by episodic marine incursions. The ages of the dwogs (1128–969 cal BC; cal AD 1426–1467) do not correlate with known layers of adjacent settlement sites and are critically discussed. However, we show that they correlate with phases of stagnant regional relative sea level (RSL) and can be used as RSL indicators. The combined archive and modern data provide valuable information for the RSL reconstruction and palaeoenvironmental changes. However, further research is recommended to accomplish more detailed information about coastal response during the Holocene sea-level changes and implications for settlement dynamics.     

Worldwide cases of water pollution by emerging contaminants: a review

Environmental Chemistry Letters - Water contamination by emerging contaminants is increasing in the context of rising urbanization, industrialization, and agriculture production. Emerging...     

Comparison of four measuring techniques to assess growth inhibition in standardized tests with seven freshwater algae and cyanobacteria

As representatives of primary producers, algae and cyanobacteria play an important role in assessing the risk of chemicals. However, the list of standard algal species commonly used for toxicity testing comprises very few species so that there is an urgent demand to identify further non-standard species which can be used for higher-tier risk assessment in general and the analysis of species sensitivity distributions in particular. In this study, four measuring techniques to assess growth inhibition were compared using five non-standard and two standard algal species and 3,5-dichlorophenol as reference substance. Regarding sensitivity and suitability, the measuring techniques were ranked in the following descending order: delayed fluorescence, prompt fluorescence, photometric absorbance, and microscopic cell count. All five non-standard species fulfilled the validity criteria if tested with delayed fluorescence.     

Evidence of nitrification and denitrification in high and low microbial abundance sponges

Aerobic and anaerobic microbial key processes were quantified and compared to microbial numbers and morphological structure in Mediterranean sponges. Direct counts on histological sections stained with DAPI showed that sponges with high microbial abundances (HMA sponges) have a denser morphological structure with a reduced aquiferous system compared to low microbial abundance (LMA) sponges. In Dysidea avara, the LMA sponge, rates of nitrification and denitrification were higher than in the HMA sponge Chondrosia reniformis, while anaerobic ammonium oxidation and sulfate reduction were below detection in both species. This study shows that LMA sponges may host physiologically similar microbes with comparable or even higher metabolic rates than HMA sponges, and that anaerobic processes such as denitrification can be found both in HMA and LMA sponges. A higher concentration of microorganisms in the mesohyl of HMA compared to LMA sponges may indicate a stronger retention of and, hence, a possible benefit from associated microbes.     

<Emphasis Type="Italic">Sympagohydra tuuli</Emphasis> (Cnidaria,Hydrozoa): first report from sea ice of the central Arctic Ocean and insights into histology,reproduction and locomotion

Various cnidarians have adapted their life style to interstitial habitats of marine sediments. Recently, for the first time a hydroid was reported from the interstitial brine channel system of Arctic fast ice. Due to its derived features, the new genus and species Sympagohydra tuuli was introduced. Here we describe findings of S. tuuli in sea ice at several sites within the central Arctic Ocean. In our view the results of this study do not allow assignment of Sympagohydra to any known family and we, therefore, suggest the introduction of a new family Sympagohydridae which is placed within the hydrozoan subclass Hydroidolina, order Anthomedusae, suborder Capitata. A first detailed histological analysis of S. tuuli is presented. In vivo analysis of locomotion and reproduction revealed a remarkable convergent evolution in S. tuuli and distant meiobenthic relatives. Shared traits are a flagellated epidermis enabling the animals to glide within small interstices by means of flagellar beating as well as an internalised embryogenesis. In S. tuuli gametogenesis occurs in the absence of gonophores inbetween gastro- and epidermis clearly separated from the epidermis. Budding was observed as the vegetative mode of reproduction. Documentation of feeding behaviour identified copepod nauplii and rotifers as prey items and demonstrates a high trophical position of the hydroids within the sympagic food web. Occurrence of reproducing individuals and pronounced tolerances towards changing temperatures and salinities indicate S. tuuli as a truly sympagic species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Biomonitoring of tin and arsenic in different compartments of a limnic ecosystem with emphasis on Corbicula fluminea and Dikerogammarus villosus

Asian clam Corbicula fluminea, the amphipod Dikerogammarus villosus and the macrophyte Nuphar lutea were tested for investigating spatial and temporal variability in the bioavailability of tin and arsenic in the River Lippe, Germany. Samples were collected from September 2002 to May 2003 at a tin polluted site (source pollution) and a reference site. Additional screening sampling was carried out twice in April 2003 to test the extent of As and Sn concentration in periphyton (aufwuchs) samples. Accumulated Sn and As concentrations were measured with ICP-MS after sample processing (dissection, cryo-milling) and digestion. Quality control was performed by parallel analysis of three certified reference materials. Measurable As and Sn contents in plant tissues were only detectable in roots (below 30 microg kg(-1) and 20 microg kg(-1) for As and Sn, respectively). Homogenates from C. fluminea and D. villosus tissues showed site-dependent trace metal contents. Elevated bioavailability of Sn is present downstream of the sewage discharge of the world's biggest producer of tributyltin (TBT) at Luenen (northern Ruhr region). In comparison to C. fluminea, D. villosus shows higher concentrations of tin in samples from both sites. Arsenic concentrations in C. fluminea remain constant with increasing shell size, whereas tin shows a size-dependent accumulation. The results indicate that Corbicula fluminea and Dikerogammarus villosus are suitable passive biomonitoring organisms for Sn, but As levels might be actively regulated. The concentration of tin in the periphyton (aufwuchs) samples was found to be much higher in samples from a contaminated site (428 +/- 63 vs. 1949 +/- 226 microg kg(-1)).     

Social behavior of free-ranging juvenile sooty mangabeys (Cercocebus torquatus atys)

Sooty mangabeys are terrestrial monkeys exhibiting female philopatry and male dispersal. Studies in captivity as well as in the wild have found that adult females form linear dominance hierarchies. However, while captive studies found no evidence for a matrilineal social system, a previous study in Taï National Park, Ivory Coast, suggested that relatedness could influence both dominance rank and affiliation pattern among adult females. Here I test whether the dominance rank, coalitionary behavior, and affiliative behavior of juveniles in a group of free-ranging mangabeys in the Taï National Park are in accordance with a matrilineal, individual, or age-related dominance system. I found that juvenile females' dominance ranks remained stable over time and were highly correlated with the dominance ranks of their mothers, whereas juvenile males' dominance ranks were initially correlated with the ranks of their mothers, but showed greater instability with increasing age. Moreover, coalitions occurred mainly between juveniles and animals that were close in rank, including their mothers and siblings. Finally, juvenile females associated and groomed preferentially with close-ranking juvenile and adult females. Juvenile males showed similar preferences in affiliation with adult females, but when associating with juvenile males, they preferred peers. The observed social behavior of free-ranging juvenile sooty mangabeys resembled the social behavior described for juveniles of many matrilineal primate species.     

In vivo measurements of the internal pH of Hediste (Nereis) diversicolor (Annelida, Polychaeta) exposed to ambient sulphidic conditions using pH microelectrodes

 The effect of different ambient sulphide concentrations on the internal pH regime of Hediste (Nereis) diversicolor was studied under in vivo conditions using liquid membrane pH microelectrodes, a method which is new to marine sciences. As a case study, the hypothesis was tested whether organisms exposed to ambient sulphidic conditions are able to lower their internal pH which, in effect, would reduce sulphide influx into the animals and thus could represent an effective detoxification mechanism. It was shown that a significant lowering of the internal pH occurred within only 20 min after adding sulphide. This pH lowering appeared to be dependent on the external sulphide concentration of the ambient medium and showed a saturation beyond a threshold level of about 130 μM. It is discussed whether this sulphide-induced pH drop is an active regulatory mechanism and acts as an effective protection mechanism against sulphide during short-term exposures. Received: 1 June 1999 / Accepted in revised form: 3 May 2000