Uranium uptake and depuration in the aquatic invertebrate Chironomus tentans

Evaluation of aqueous uranium (U) uptake and depuration in larvae of the midge Chironomus tentans were investigated in two separated experiments. First, a static-renewal experiment was performed with 10-d old C. tentans larvae exposed to 300 μg U/L. The animals steadily accumulated U (K_u = 20.3) approaching steady-state conditions (BAF = 56) in approximately 9-11 d. However, accumulated U was readily depurated (K_d = 0.36) with U tissue concentration decreasing rapidly within 3 d of the larvae being placed in clean water (t_1/2 = 1.9 d). Also, the growth of C. tentans larvae appeared to decrease after 6-11 d of U exposure, probably due to the reallocation of resources into U detoxification mechanisms. However, growth significantly increased once C. tentans were transferred to clean water. A separate short-term experiment was performed to evaluate the possible mechanism of U uptake in this invertebrate. Results suggested a passive mechanism of U uptake coupled with an active mechanism of U depuration but no details related to the type of mechanisms or pathway was investigated.     

Biomonitoring von Stickstoffimmissionen

Background and aim

Air pollution caused by oxidized and reduced nitrogen is distributed over wide areas of Europe at a high level. As an alternative or complement to physical measurements and modelling calculations, biomonitoring with plants provides techniques to assess amounts and effects of pollution from oxidized and reduced nitrogen compounds (depositions and concentrations). Many of the previously implemented techniques are based on well-proven standardised methods, e.g. documented in VDI guidelines, modified more or less for a biomonitoring of atmospheric nitrogen pollution. This paper gives a review of the techniques for a biomonitoring of atmospheric nitrogen pollution, their possibilities as well as their limitations.

Main features

-diversity of the ground vegetation

-nitrogen accumulation in vascular plants

-exposure of vascular plants

-mapping of epiphytic lichens, bryophytes and algae

-nitrogen accumulation in lichens and bryophytes

-exposure of lichens and bryophytes

Results and Discussion

Important response parameters are nitrogen concentrations in plant tissue (shoot, needle, leave) and biodiversity of plant species. These responses of vascular plants in many cases are influenced by other local varying conditions, in particular the soil. The exposure of vascular plants over a short period provides a standardised quantification of the total atmospheric nitrogen input in a model ecosystem. The enrichment of nitrogen in the plant tissue of bryophytes and lichens from the ground vegetation is closely correlated with the amount of nitrogen deposition. The diversity of epiphytic lichens and the response of exposed Hypogymnia physodes is more sensitive to ammonia than to nitrous oxide, whereas with the diversity of epiphytic bryophytes or the abundance of algae no significant correlation with atmospheric N pollution were found.

Conclusions

Some bioindication techniques provide a causeeffect related, partly standardised biomonitoring of nitrogen pollution. In some cases varying experiences with some biomonitors like the biodiversity of the ground vegetation, exposure of lichens, moss bags and grass cultures stress the need for more research in this subject.     

Schnelle vor-ort-analytik zur untersuchung von rüstungsaltlasten

Field screening methods for the analysis of explosives (for which commercial test kits are generally available) are reviewed. These techniques include immunoassays, photometric methods, bio and chemical sensors as well as thin layer chromatography. Basic aspects of these techniques are discussed, their validation is presented and their application to water and soil samples from hazardous ammunition waste is described. An evaluation of field studies with commercial test kits demonstrates that these techniques can be applied successfully for both the exploration of suspected contaminated sites and their sanitation. These methods are used on-site. In general, they allow short analysis times and a high sample throughput, thus leading to a significant reduction of the number of samples to be analysed in the laboratory and the costs.     

Investigation of partitioning mechanism for volatile organic compounds in a multiphase system

Laboratory experiments were performed to investigate the partitioning behavior of a set of diverse volatile organic compounds (VOCs). After equilibration at a temperature of 25 °C, the VOC concentrations were measured by headspace method in combination with gas chromatography/mass spectrometry (GC/MS). The obtained data were used to determine the partition coefficients (K_P) of VOCs in a gas-liguid-solid system. The results have shown that the presence and nature of solid materials in the working solution control the air-water partitioning of dissolved VOCs. The air/solution partitioning of BTEX and C₉-C₁₀ aldehydes was most affected in the presence of diesel soot. K_P values decreased by a factor ranging from 1.5 for toluene to 3.0 for ethylbenzene. The addition of mineral dust in the working solution exhibited greater influence on the partitioning of short aldehydes. K_P values decreased by a factor of 1.8. The experimental partition coefficients were used to develop a predictive model for partitioning of BTEX and n-aldehydes between air, water and solid phases.     

Fluorescence imaging applied to tracer distributions in variably saturated fractured clayey till

The study of mechanisms controlling preferential flow and transport in variably saturated fractured clayey till is often hindered by insufficient spatial resolution or unknown measuring volume. With the objective to study these mechanisms while circumventing the obstacles, tracer experiments with two fluorescent tracers Acid Yellow 7 (AY7) and Sulforhodamine B (SB) were performed at three different rain events for a fall and a summer season. Irrigated areas were excavated down to depths of 2.8 m and the movement of both tracers in the exposed profiles was delineated simultaneously by high spatial resolution apparent concentration maps (pixel approximately 1 mm(2)) obtained with an imaging device. The device consists of a light source and a CCD camera, both equipped with tracer-specific-filters for fluorescent light. The fluorescence images were corrected for nonuniform lighting, changing surface roughness, and varying optical properties of the soil profile. The resulting two-dimensional apparent concentration distribution profiles of the tracers showed that: (i) relative low water content in the upper 10 cm of the irrigated till in summer had a pronounced retardation effect on the AY7-migration and no effect on the SB-migration; (ii) the dead-end biopores were not activated in the fall season; (iii) only 3D fracture-plans connected to hydraulically active 1D-biopores contributed to the leaching; (iv) the tracer migration primary followed macropores during both seasons, though AY7 also followed a topsoil piston transport in summer; (v) the highest tracer pixel apparent concentrations were often found in macropores and most pronounced in the summer season; and (vi) 3D-dilution in fractures seems to play a dominating role in AY7-migration in the fall season.     

Impact of Sodium Chloride, Sucrose and Milk on Heat Stability of the Murine Norovirus and the MS2 Phage

Until now, little is known about the influence of food additives on heat inactivation of noroviruses. Only a few studies have shown a protective or inhibiting effect on virus infectivity caused by the food matrix. Therefore, the aim of this study was to examine the influence of sodium chloride, sucrose and milk on heat stability of the surrogates murine norovirus (MNV) and MS2 phage at 60 °C for 1–5 min in PBS for MNV and for 5–120 min in suspension medium buffer for MS2 phage. Different concentrations of sodium chloride (5, 10 %) and sucrose (5, 50 %) were added to the respective buffers. In addition, commercially available milk with different fat concentrations (0.3, 1.5, 3.5 %) was investigated in this study. In general, a linear titre reduction for MNV and MS2 phage could be observed, except for the heat treatment of MNV in PBS with 50 % sucrose. A protective effect of PBS with 50 % sucrose and of the matrix milk on MNV could be concluded. All other tested conditions did not show any influence on virus inactivation. However, MS2 phage did show a higher heat resistance throughout the experiments compared to MNV. In future investigations, it should be tested, whether the achieved data may be considered in risk assessments of heat-treated food products with high concentrations of sugar. Furthermore, it should be clarified, whether these results can also be referred to complex food matrices.     

Adaption to Extreme Rainfall with Open Urban Drainage System: An Integrated Hydrological Cost-Benefit Analysis

This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas. The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken.     

Seasonal variation in ecophysiological patterns in macroalgae from an Arctic fjord. I. Sensitivity of photosynthesis to ultraviolet radiation

Marine macroalgae inhabiting Arctic coastal ecosystems are exposed to pronounced seasonal variations in the radiation regime, including harmful UVB radiation. This study presents the first data on the seasonal changes in the sensitivity of macroalgal photosynthesis towards UV exposure by comparing under-ice, clear-water and turbid-water conditions characteristic for late winter, spring and summer. Various brown (Laminaria saccharina, L. digitata, L. solidungula, Saccorhiza dermatodea, Desmarestia aculeata), red (Palmaria palmata, Devaleraea ramentacea) and one green macroalgal species (Monostroma aff. arcticum) were collected at the same water depth throughout the seasons in the Kongsfjord (Spitsbergen, Svalbard, Norway). Maximum quantum yield (F_v/F_m) and maximum photosynthetic electron transport rates (ETR_max) were determined immediately after collection, after 2 h exposure to artificial UV radiation and after 18 h recovery in dim white light. Photosynthesis of the studied species showed different responses depending on their morpho-functional and physiological characteristics, their life strategies, phenology and depth distribution. Within the genus Laminaria, maximum quantum yield of adult specimens of the deep-water species L. solidungula was most strongly UV sensitive. Adult L. saccharina exhibited a lower UV sensitivity than a 6-month-old specimen. Inhibition of photosynthesis after UV exposure remained at the same level throughout the study period, both in adult L. saccharina and S. dermatodea. However, adult specimens of L. saccharina collected in May showed partial recovery only, whereas photosynthesis of specimens from both species collected later recovered fully. D. aculeata exhibited a remarkable decrease of UV sensitivity during the study period. Photosynthesis of specimens collected under the ice was strongly inhibited by UV, but the degree of inhibition decreased during spring and summer. Concomitantly ETR_max values were low after UV exposure in specimens collected in June, but increased later in the season. P. palmata exhibited a relatively flexible response. Photosynthesis in specimens collected under the ice in June or in turbid water in July/August was relatively strongly inhibited; specimens collected during sunny periods and in clear water in spring showed a much lower degree of photoinhibition after UV exposure. The seasonal pattern of low/high ETR_max values in spring/summer is probably a characteristic of the life strategy of this species. The UV sensitivity of D. ramentacea exhibited a similar seasonal pattern. In M. aff. arcticum, UV sensitivity increased and ETR_max values decreased during the study period, reflecting the life strategy of this annual late winter/spring species. The physiological basis for the seasonal changes in UV sensitivity of photosynthesis is presented in a companion paper (this issue).     

Species-specific responses of herbivores to within-plant and environmentally mediated between-plant variability in plant chemistry

Allocation of resources to growth and defense against herbivores crucially affects plant competitiveness and survival, resulting in a specific distribution of assimilates and defense compounds within plant individuals. Additionally, plants rarely experience stable environmental conditions, and adaptations to abiotic and biotic stresses may involve shifts in resistance to herbivores. We studied the allocation of phytochemicals in Brassica oleracea (Brussels sprouts) due to leaf age, drought stress and herbivore damage and assessed effects on two lepidopteran herbivores differing in diet breadth: the generalist Spodoptera littoralis and the specialist Pieris brassicae. Glucosinolates as secondary defense compounds and total nitrogen and carbon were quantified and linked to plant palatability, i.e., herbivore feeding preference. Herbivore responses were highly species-specific and partially related to changes in phytochemicals. Spodoptera littoralis preferred middle-aged leaves with intermediate levels of glucosinolates and nitrogen over young, glucosinolate and nitrogen rich leaves, as well as over old leaves, poor in glucosinolates and nitrogen. In contrast, P. brassicae preferred young leaves. Both species preferred severely drought-stressed plants to the well-watered control, although analyzed glucosinolate concentrations did not differ. Both S. littoralis and P. brassicae feeding induced an increase of indole glucosinolate levels, which may explain a reduced consumption of damaged plants detected for S. littoralis but not for P. brassicae. By revealing distinct, sometimes contrasting responses of two insect herbivores to within-plant and stress-mediated intraspecific variation in phytochemistry of B. oleracea, this study emphasizes the need to consider specific herbivore responses to understand and predict the interactions between herbivores and variable plants.     

The cockle <Emphasis Type="Italic">Cerastoderma edule</Emphasis> at Northeast Atlantic shores: genetic signatures of glacial refugia

The cockle Cerastoderma (Cardium) edule (L.) ranges from NW Africa to northern Scandinavia. Abundance in shallow coastal sediment is often high, and it attracts commercial harvest. In this study, a complex genetic pattern has been revealed by mitochondrial DNA in 383 individuals from 19 sampling sites. Parsimony network analysis of 79 haplotypes identified two dominant central haplotypes separated by low divergence. One is characteristic for a homogenous southwestern group of populations from Africa to the British Isles. The other is characteristic for a heterogeneous northern group with a deviant Arctic population. At the entrance of the Baltic Sea, a mixture zone of the dominant haplotypes was found. The estimated population expansion time for the northern haplotype group predates that of the southwestern one, suggesting northern glacial refugia and a subsequent southern expansion of C. edule populations.