Sediment Properties for Assessing the Erosion Risk of Contaminated Riverine Sites. An approach to evaluate sediment properties and their covariance patterns over depth in relation to erosion resistance. First investigations in natural sediments (11 pp)     

Sabine U. Gerbersdorf  Thomas Jancke  Bernhard Westrich 《Journal of Soils and Sediments》2007,7(1):25-35

Background, Aim and Scope   Riverine sediments store large quantities of hazardous contaminants, remaining a 'legacy of the past' world-wide. Natural events such as floods may cause the resuspension of polluted sediments and accordingly, the former immobilized contaminants might become bioavailable and toxic again. Hence, a comprehensive erosion risk assessment of contaminated sites is of crucial importance. The present study aimed to implement 'master-variables' for a reliable, easy-to-manage and economically more viable determination of stability in cohesive sediments. Materials and Methods: A wide range of physico-chemical (bulk density, water content, particle size, mineral composition, cation exchange capacity / CEC, total organic matter / TOC, liquid and plastic limits of a soil) and biological (macrofauna abundances, microalgal biomass and species composition, bacterial cell numbers, EPS fractions such as carbohydrates and proteins) properties were determined simultaneously over depth spanning the zone between 0-35 cm. The data were related to sediment stability, determined as the 'critical shear stress for mass erosion' in the SETEG (Stroemungskanal zur Ermittlung der tiefenabhaengigen Erosionsstabilitaet von Gewaessersedimenten) - flume. The investigations were done on natural sediments, thereby covering vertical (over depth), spatial (different study sites) and temporal (different seasons) aspects to ensure the transferability of the data. Here, first data originating from three contaminated reservoirs in the lock-regulated River Neckar / Germany are presented. Results: Comparison of the rather low critical shear stress values (resisting force of sediment, determined in SETEG) with the possibly occurring natural bottom shear stresses (attacking force, calculated for different hydraulic scenarios) at the three reservoirs indicated a severe risk of sediment erosion even under moderate hydraulic conditions and was not restricted to the surface. Critical shear stress was characterised by the following sediment properties of depth, grain size, CEC (Cation Exchange Capacity) and concentrations of TOC (Total Organic Carbon), proteins as well as carbohydrates (water- and resin-extractable). Firstly, biological stabilisation by extracellular polymeric substances (EPS) could be shown for riverine sediments, even over depth. Secondly, erosion resistance was determined by the inter-particles forces, an interplay of the biologically produced compounds constituting active surfaces and the binding capacity as well as charge densities of the sediments. The combined influence of sedimentological and biological properties on sediment stability over depth was assessed by PCA (Principal Component Analysis). Discussion: Hence, a better correlation coefficient between sediment stability and the master variables could be achieved (Main component II: Polymeric substances, R = 0.7, Main component III: Grain size, TOC, CEC, R = 0.9) compared to single correlations. Conclusions: The present paper revealed the combined influence of physico-chemical and biological properties on sediment stability over depth by simultaneous investigation and statistical evaluation. It can be shown, that inter-particle forces, determined by particles size classes, CEC, TOC and polymeric substances such as proteins and carbohydrates, affected sediment stability most. Thereby, the impact of biogenic sediment mediation on riverine sediment stabilisation became evident, even over depth, where mostly sedimentological parameters were considered as important before. Recommendations and Perspectives: The importance of a comprehensive risk assessment of contaminated riverine sites was again highlighted in the present study by the comparison of natural occurring bottom shear stresses with the determined sediment erosion resistance. If a realistic risk assessment is to be derived, the stabilizing potential of micro-organisms needs to be taken into account and the covariance patterns of biological and physico-chemical sediment properties have to be addressed.  相似文献   

Local and global inverse modelling strategies to estimate parameters for pesticide leaching from lysimeter studies          下载免费PDF全文

Gunnar M Kahl  Yury Sidorenko  Bernhard Gottesbüren 《Pest management science》2015,71(4):616-631

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Effects of temperature, wetness duration and leaf age on incubation and latent periods of black leaf mold (Pseudocercospora fuligena) on fresh market tomatoes   总被引：1，自引：0，他引：1  

Zelalem Mersha  Shouan Zhang  Bernhard Hau 《European journal of plant pathology / European Foundation for Plant Pathology》2014,138(1):39-49

Black leaf mold (BLM), caused by Pseudocercospora fuligena is a serious threat to tomato production in the humid tropics. Accurate information about the incubation (IP) and latent period (LP) under various host susceptibility and weather favourability circumstances will help to formulate holistic approaches to manage this disease. In this study, effects of temperature, wetness duration, and leaf age on the monocyclic components (IP and LP) of BLM were studied from growth chamber (GC) and greenhouse (GH) experiments as well as detached leaf assays in growth cabins. Linear interpolation and inflection point (of logistic regression model) methods were used to determine IP and LP. These two methods were highly correlated in GC (r ²?=?0.89; P?<?0.0001) and GH experiments (r ²?=?0.90; P?<?0.0001) except when the epidemics were not asymptotic. Thus, IP and LP were estimated according to inflection point method. There was a delay of at least 5 days of IP and LP when plants were left in non-humid open environment than when exposed to wetness durations of 1, 2 or 3 days after inoculation. In general, IP and LP became shorter as the temperature increased from 20–24 and then to 28 °C. In growth chambers, there was more disease and consequently shorter IP and LP on young and unfolded tomato leaves that were 1-, 3-, or 5-week old at the time of inoculation than 7-week old leaves. In the greenhouse, there was about 50 % more disease incidence and sporulation on 1-week than 3-week old leaves. The shortest IP (8–11 days) and LP (12–13 days) were recorded from two out of three GH experiments on 1-week old leaves at an ambient mean temperature of 28.5 °C. This study implicated that fresh market tomatoes planted during warm temperatures in 50-mesh greenhouses and exposed to extended periods of wetness are highly prone to BLM infection at their young stages of growth.  相似文献   

Effect of the estimation of forest management and decay of dead woody material on the reliability of carbon stock and carbon stock changes—A simulation study     

Michael Khl  Wolfgang Stümer  Bernhard Kenter  Thomas Riedel 《Forest Ecology and Management》2008,256(3):229-236

The IPCC-GPG on Greenhouse Gas Monitoring offers countries several options for reporting. The current study selected management effects and decay of dead woody material to demonstrate the dependence of different approaches and assumptions for carbon stock and carbon stock change estimates. For a given set of inventory data the reported change of carbon stock varied between 3.1 tonnes C ha⁻¹ yr⁻¹and 34.4 tonnes C ha⁻¹ yr⁻¹ for a 10-year period.Based on the available data set from a test area in the federal state of Salzburg (Austria) the effect of different scenarios for harvesting operations and mortality on reported carbon release was studied. The scenarios covered timber utilization at different points in time and two mortality rates (constant and exponential). A proportion of harvesting was assumed to remain inside the forest as logging residues and entered together with mortality a decay process. Two different lifetimes for decay (10 and 50 years) and constant and negative exponential decay rates were simulated. Those decisions affect the amount of carbon released considerably. For a 10-year period between 5% and 80% of the carbon content of dead woody material that accumulated within the period is released to the atmosphere.  相似文献   

Comparing the financial performance of traditionally managed beech and oak stands with roomy established and pruned stands     

Bernhard Beinhofer 《European Journal of Forest Research》2010,129(2):175-187

Beech and oak stands are normally established with high numbers of plants. On one hand, this costs a lot, but on the other hand, knot-free timber may be expected only in this way. This study analyses whether roomy establishment and, as a result, lower timber quality lead to financial advantages over the normal treatment. In addition to this, it is tested if pruning of roomy established beech and oak stands is financially advantageous. For this valuation, conventionally managed stands were simulated with the forest growth simulator Silva and for the roomy established stands, data from trial plots were completed with Silva. The development of the pruned oak stands followed the yield table of Jobling and Pearce (Free growth of oak, Forest record number 113, Forestry Commission HMSO, London, 1977), while for beech the development of the diameters orientated to an investigation of Hasenauer et al. (Österr Forstztg 105:28–29, 1994). Based on the assortments contained in the stands, a valuation of the different treatments was done with annuities within a Monte Carlo simulation, thereby including the volatility of timber prices and the risk of natural hazards. Additionally, the imputed costs per cubic meter of produced timber and the minimum share of high-value assortments on the pruned trunks were calculated for the required rates of return of 1, 2 and 3%. The conventionally managed beech and oak stands were found to be inferior from the financial point of view. Even the non-pruned stands with roomy establishment were superior despite the lower timber quality. The minimum share of high-value assortments on the pruned trunks were between 6 and 410%. Particularly in the case of high values of the land, the maximum volume of high-value assortments was not sufficient to achieve certain rates of return. Nevertheless, the stands with pruning and low-density management were more profitable. In addition to this, it was ascertained that pruning of beech and oak is possible and does not hinder the production of high-value assortments.  相似文献   

Structural diversity of English yew (<Emphasis Type="Italic">Taxus baccata</Emphasis> L.) populations     

Herwig Ruprecht  Amalesh Dhar  Bernhard Aigner  Gerald Oitzinger  Raphael Klumpp  Harald Vacik 《European Journal of Forest Research》2010,129(2):189-198

In Europe, the English yew species (Taxus baccata L.) is endangered. Intensive human land-use, including forest management, has caused a decrease of the yew populations all over Europe. In Austria, gene conservation forests are used for the in situ conservation of populations of this rare tree species by silvicultural treatments. In order to improve the conservation management in these gene conservation forests, this study addresses the relation between competition and viability of yew populations through the use of structural diversity indices. The structural indices, which include mingling, tree–tree distance, diameter, and tree height differentiation, were determined for a structural group of four trees as well as the neighbouring trees of the male and female yews at the monitoring plots on a regular grid in three gene conservation forests. Although the three study sites provided quite different environmental conditions for English yew, the vitality of each individual yew was influenced by the inter-specific competition of the neighbouring tree species at all sites. Low vitality was associated with a small mean distance to neighbours and large tree height differentiation. In conclusion, we suggest that a combination of different structural indicators is needed for an integrative assessment of conservation status in the gene conservation forests. This would help improve the evaluation of the impact management has on yew population viability.  相似文献   

Evaluation of a rebound tonometer (Tonovet^®) in clinically normal cat eyes     

Elina Rusanen†  Marion Florin†  Michael Hässig‡  Bernhard M. Spiess† 《Veterinary ophthalmology》2010,13(1):31-36

Objective  To determine the accuracy of and to establish reference values for a rebound tonometer (Tonovet^®) in normal feline eyes, to compare it with an applanation tonometer (Tonopen Vet^®) and to evaluate the effect of topical anesthesia on rebound tonometry.
Procedures  Six enucleated eyes were used to compare both tonometers with direct manometry. Intraocular pressure (IOP) was measured in 100 cats to establish reference values for rebound tonometry. Of these, 22 cats were used to compare rebound tonometry with and without topical anesthesia and 33 cats to compare the rebound and applanation tonometers. All evaluated eyes were free of ocular disease.
Results  Both tonometers correlated well with direct manometry. The best agreement with the rebound tonometer was achieved between 25–50 mmHg. The applanation tonometer was accurate at pressures between 0 and 30 mmHg. The mean IOP in clinically normal cats was 20.74 mmHg with the rebound tonometer and 18.4 mmHg with the applanation tonometer. Topical anesthesia did not significantly affect rebound tonometry.
Conclusions  As the rebound tonometer correlated well with direct manometry in the clinically important pressure range and was well tolerated by cats, it appears suitable for glaucoma diagnosis. The mean IOP obtained with the rebound tonometer was 2–3 mmHg higher than that measured with the applanation tonometer. This difference is within clinically acceptable limits, but indicates that the same type of tonometer should be used in follow-up examinations in a given cat.  相似文献   

Hydraulic traits and tree-ring width in <Emphasis Type="Italic">Larix sibirica</Emphasis> Ledeb. as affected by summer drought and forest fragmentation in the Mongolian forest steppe     

Elmira Khansaritoreh  Bernhard Schuldt  Choimaa Dulamsuren 《Annals of Forest Science》2018,75(1):30

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Metropolitan farmers markets in Minneapolis and Vienna: a values-based comparison     

Milena Klimek  Jim Bingen  Bernhard Freyer 《Agriculture and Human Values》2018,35(1):83-97

Farmers markets (FMs) have traditionally served as a space for farmers to sell directly to consumers. Recently, many FMs in the US and other regions have experienced a renaissance. This article compares the different value sets embedded in the rules and norms of two metropolitan FM regions—Minneapolis, Minnesota and in Vienna, Austria. It uses a values-based framework that reflects the relationships among FM operating structures (OS) and their values reflected by the key FM participants—i.e., farmer/vendors, consumers and market managers. The framework allows us to focus on two very contrasting value sets of metropolitan FM regions in (1) presenting and discussing the values found and embedded in the two metropolitan market regions; (2) illustrating how the values found are embodied as rules and norms in each FM region; (3) considering the alignment or not of FM participant values with their corresponding FM values; and (4) the differences and commonalities as well as the benefits and challenges of the two market regions. In contrasting metropolitan FMs we explain that FM value sets are complex and differ among and within FM participant groups and are dependent on their respective OS. We show that contrasting two metropolitan FM regions can be useful in understanding beneficial and disadvantageous relationships between the values and structures of, and in FMs, and specifically in examining institutional impediments such as governance. Thus we illustrate the possibilities and limitations of values for and within metropolitan FMs.  相似文献   

Sub‐Tenon's injection in equine cadaver eyes: MRI visualization of anesthetic fluid distribution and comparison of two different volumes          下载免费PDF全文

Silvia Stadler  Matthias Dennler  Udo Hetzel  Francesca Del Chicca  Sèamus Hoey  Bernhard M. Spiess  Katrin Voelter  Simon A. Pot 《Veterinary ophthalmology》2017,20(6):488-495

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