Endpoint ‘floating leaves’ of <Emphasis Type="Italic">Potamogeton natans</Emphasis>: A new method to evaluate the development of macrophytes in pond mesocosms

Goal, Scope and Background One of the advantages of long-term mesocosm experiments as compared to short-term standard toxicity tests in the laboratory is the potential for detecting secondary effects due to the interaction of species and recovery with biomass of macrophytes being an important endpoint. However, generating biomass data by harvesting is often laborious, time-consuming, costly and restricted to the end of the experiment. Moreover, valuable information may get lost, in particular in single application studies, since maximal primary effects and secondary effects or recovery occur per se at different times. Potamogeton natans was used as an example in order to test whether number and area of floating leaves can be reliably measured and be used as intermediate and final endpoints in mesocosm effect studies. Methods Digital photos, which were taken of the water surface in the course of an indoor pond mesocosm study on herbicide effects, were subjected to image analysis. The results were compared to wet weight and ash-free dry weight of Potamogeton at the end of the herbicide study. Results and Discussion Both number and area of floating leaves indicated the same herbicide effects as wet weight and ash-free dry weight of Potamogeton. Error introduced by the different work steps is small and can be further minimised by a number of method improvements. Recommendations and Perspectives In indoor mesocosm studies, errors due to the perspective adjustment may be circumvented by taking the photos perpendicular to the water surface. Correction for lens aberration, identical light conditions and the use of fluorescence images are considered promising. Field applications are proposed.     

Net methylmercury production as a basis for improved risk assessment of mercury-contaminated sediments

Sediments contaminated by various sources of mercury (Hg) were studied at 8 sites in Sweden covering wide ranges of climate, salinity, and sediment types. At all sites, biota (plankton, sediment living organisms, and fish) showed enhanced concentrations of Hg relative to corresponding organisms at nearby reference sites. The key process determining the risk at these sites is the net transformation of inorganic Hg to the highly toxic and bioavailable methylmercury (MeHg). Accordingly, Hg concentrations in Perca fluviatilis were more strongly correlated to MeHg (p < 0.05) than to inorganic Hg concentrations in the sediments. At all sites, except one, concentrations of inorganic Hg (2-55 microg g(-1)) in sediments were significantly, positively correlated to the concentration of MeHg (4-90 ng g(-1)). The MeHg/Hg ratio (which is assumed to reflect the net production of MeHg normalized to the Hg concentration) varied widely among sites. The highest MeHg/Hg ratios were encountered in loose-fiber sediments situated in southern freshwaters, and the lowest ratios were found in brackish-water sediments and firm, minerogenic sediments at the northernmost freshwater site. This pattern may be explained by an increased MeHg production by methylating bacteria with increasing temperature, availability of energy-rich organic matter (which is correlated with primary production), and availability of neutral Hg sulfides in the sediment pore waters. These factors therefore need to be considered when the risk associated with Hg-contaminated sediments is assessed.     

Effect of Aging on Brain Injury Prediction in Rotational Head Trauma—A Parameter Study with a Rat Finite Element Model

Objective: The aim of this study was to investigate the possible effects of age-related intracranial changes on the potential outcome of diffuse axonal injuries and acute subdural hematoma under rotational head loading.

Methods: A simulation-based parametric study was conducted using an updated and validated finite element model of a rat head. The validation included a comparison of predicted brain cortex sliding with respect to the skull. Further, model material properties were modified to account for aging; predicted tissue strains were compared with experimental data in which groups of rats in 2 different lifecycle stages, young adult and mature adult, were subjected to rotational trauma. For the parameter study, 2 age-dependent factors—brain volume and region-specific brain material properties—were implemented into the model. The models young adult and old age were subjected to several injurious and subinjurious sagittal plane rotational acceleration levels.

Results: Sequential analysis of the simulated trauma progression indicates that an increase in acute subdural hematoma injury risk indicator occurs at an early stage of the trauma, whereas an increase in diffuse axonal injury risk indicators occurs at a later stage. Tissue stiffening from young adult to mature adult rats produced an increase in strain-based thresholds accompanied by a wider spread of strain distribution toward the rear part of the brain, consistent with rotational trauma experiments with young adult and mature adult rats. Young adult to old age brain tissue softening and brain atrophy resulted in an increase in diffuse axonal injuries and acute subdural hematoma injury risk indicators, respectively.

Conclusions: The findings presented in this study suggest that age-specific injury thresholds should be developed to enable the development of superior restraint systems for the elderly. The findings also motivate other further studies on age-dependency of head trauma.     

Compromising sustainable mobility? The case of the Gothenburg congestion tax

Congestion charging is widely considered an effective policy measure to regulate and reduce car traffic demand and associated environmental and health problems in cities. However, introducing restrictive measures to constrain individual choice and behaviour for the common good has often proven difficult. Using a specific case, the Gothenburg congestion tax introduced in 2013, we study the policy process behind the introduction of the tax and assess to what extent green values were compromised along the way. The tax was made possible by co-financing infrastructure investments, including roads, which seemingly contradicts stated goals of reducing car traffic and emissions. We show how the tax was ‘muddled through’ in a top-down political compromise by a grand coalition where different interests could legitimate their support in relation to the achievement of partially conflicting objectives and projects. However, to declare the regulatory goals fully neutralised would be to underestimate the scheme's direct environmental effects and restrictive potential. Finding a compromise with powerful political and economic interests was necessary to get it off the ground. Once launched, however, it can over time regain its restrictive properties and lead to more profound long-term effects.     

Environmental risk perception, environmental concern and propensity to participate in organic farming programmes

This paper aims to identify the factors underlying farmers' propensity to participate in organic farming programmes in a Romanian rural region that confronts non-point source pollution. For this, we employ structural equation modelling with latent variables using a specific data set collected through an agri-environmental farm survey in 2001. The model includes one 'behavioural intention' latent variable ('propensity to participate in organic farming programmes') and five 'attitude' and 'socio-economic' latent variables ('socio-demographic characteristics', 'economic characteristics', 'agri-environmental information access', 'environmental risk perception' and 'general environmental concern'). The results indicate that, overall, the model has an adequate fit to the data. All loadings are statistically significant, supporting the theoretical basis for assignment of indicators for each latent variable. The significance tests for the structural model parameters show 'environmental risk perception' as the strongest determinant of farmers' propensity to participate in organic farming programmes.     

Activity-Based Patterns of Everyday Mobility: The Potential for Long-Term Behaviour Change Across Five Groups of Travellers

Abstract

Significant differences in our mobility patterns can be found in relation to both range/distance and form. While some people travel on multiple occasions to global destinations over the course of a year, others travel mainly locally, that is, by bicycle or on foot. Policymakers and planners need to have a clear conception of the different mobility patterns if they are to develop valid and precise measures promoting more sustainable forms of mobility. This paper points to five key mobility types based on an exploratory cluster analysis of approximately 20,000 Norwegian travel diaries. Three of the defined groups are dominated by the private car, while two are oriented towards the use of public transport, bicycling and walking. The key differences and similarities between the mobility types are discussed and the relationship between everyday travel patterns and long-distance travel is analysed. Opportunities and challenges for transformations in the everyday travel habits of the five groups are discussed in the final section.     

Assessing the sustainability of forest management: An application of multi-criteria decision analysis to community forests in northern Ethiopia

Continuous deterioration of the natural resource base has become a serious threat to both the ecological systems and economic production in Ethiopia. Many of these problems have been attributed directly or indirectly to the rapid dwindling of the country's forest cover which is associated with unsustainable forest use and management. Closing community woodlands from human and livestock intervention to promote natural regeneration of forests has been one of the environmental restoration strategies pursued in the degraded highland areas of northern Ethiopia. However, local pressure to use reforested community lands for economic benefit has become a major threat to forest sustainability.Using locally identified sets of criteria and indicators for sustainable community forest management, this paper applies a multi-criteria decision analysis tool to evaluate forest management problems in the northern province of Tigray, Ethiopia. Three MCA methods – ranking, pair-wise comparison, and scoring – were used in evaluating the sets of criteria and indicators and alternative forest management scenarios.Results from the study indicate a number of noteworthy points: 1) MCA techniques both for identifying local level sustainability criteria and indicators and evaluating management schemes in a participatory decision environment appear to be effective tools to address local resource management problems; 2) Evaluated against the selected sets of criteria and indicators, the current forest management regime in the study area is not on a sustainable path; 3) Acquainting local people with adequate environmental knowledge and raising local awareness about the long-term consequences of environmental degradation ranked first among the set of sustainability criteria; and 4) In order to harmonize both environmental and economic objectives, the present ‘ecological-biased’ forest management regime needs to be substituted by an appropriate holistic scheme that takes into account stakeholders' multiple preferences and priority rankings.     

The cell-free DNA virome of 108,349 Dutch pregnant women

Objective

Viral infections during pregnancy are a major health concern to mother and fetus. By repurposing cell-free Non Invasive Prenatal Testing (NIPT) sequencing data, we investigated prevalence and abundance of viral DNA in a cohort of 108,349 pregnant women.

Method

Cell-free DNA (cfDNA) sequencing reads that did not map to any of the human chromosomes or mitochondrial DNA of the human reference genome build GRCh38 were aligned to 224 DNA viruses selected from the NCBI refseq viral database.

Results

In total 443,665 reads of viral origin were detected across 42,273 samples representing 165 viral species. Several are known to be potentially harmful during pregnancy and/or childbirth, including Cytomegalovirus, Parvovirus B19 and Hepatitis B. Viral sequences were mostly detected at very low abundance. However, several cases had exceptionally high viral loads for Parvovirus B19, Hepatitis B and others. We found statistically significant associations between presence of viral DNA and gestational age, maternal age, fetal fraction, cfDNA concentration and others.

Conclusion

We demonstrate the feasibility to detect viral DNA from typical genome-wide NIPT cfDNA sequencing and describe the main characteristics of the viral DNA in our cohort. Our dataset of detected viral sequence reads is made publicly available to guide future clinical implementations.