Comparative measurement of the redox potential of marine sediments as a rapid means of assessing the effect of organic pollution

A rapid method for measuring the redox potential (Eh) values of marine sediments is described. This method has been used to relate changes in the areas of highly reduced sediment in a sea loch system to the continuously fluctuating inputs of organic waste from a pulp and paper mill. Subsequent faunal changes in these areas can be related to changes in the measured sedimentary redox level. The method is suggested as a rapid means of assessing the potential impact of an additional organic input to a marine sediment.     

The relationship between spatial ability and environmental knowledge

This study examined the relationships between four standardized measures of spatial ability—the Embedded Figures Test (EFT), the Mental Rotations Test (MRT), the Differential Aptitude Spatial Relations subtest (DAT), and the Building Memory Test (BMT)—and two measures of environmental knowledge. Three hundred and fifty-three college undergraduates were administered the EFT, MRT, DAT, BMT and two measures of environmental knowledge-a landmark location (LM) and route knowledge (RK) task. The two environmental knowledge tasks were based on a slide-simulated walk through an unfamiliar urban environment. A principal components analysis of the above six measures produced two factors; one consisting of the four spatial ability tests, and the other the two environmental knowledge tasks. The correlation between the two factors was 0·37, indicating that the spatial ability factor accounted for 13·69% of the variance in the environmental knowledge factor.     

Greenhouse gas and alcohol emissions from feedlot steers and calves

Livestock's contributions to climate change and smog-forming emissions are a growing public policy concern. This study quantifies greenhouse gas (GHG) and alcohol emissions from calves and feedlot steers. Carbon dioxide (CO) methane (CH), nitrous oxide (NO), ethanol (EtOH), and methanol (MeOH) were measured from a total of 45 Holstein and Angus steers and 9 Holstein calves representative of four different growth stages commonly present on calf ranches and commercial feedlots. Individuals from each animal type were randomly assigned to three equal replicate groups of nine animals per group. Steers were fed a high concentrate diet and calves a milk replacer and grain supplement. Cattle and calves were housed in groups of three animals in an environmental chamber for 24 h. The CO, NO, EtOH, and MeOH concentrations from the air inlet and outlet of the chamber were measured using an INNOVA 1412 monitor and CH using a TEI 55C methane analyzer. Emission rates (g head h) were calculated. The GHGs were mainly produced by enteric fermentation and respiration and differed across life stages of cattle. Compared with dairy cows, feedlot steers produce relatively less GHG. In general, ethanol and methanol, the most important volatile organic compound (VOC) group in the dairy sector, were below the lower limit of detection of the gas analyzer. The present data will be useful to verify models and to enhance GHG emission inventories for enteric fermentation, respiration, and fresh excreta for numerous cattle life stages across the beef industry.     

Environmental Flows Can Reduce the Encroachment of Terrestrial Vegetation into River Channels: A Systematic Literature Review

Encroachment of riparian vegetation into regulated river channels exerts control over fluvial processes, channel morphology, and aquatic ecology. Reducing encroachment of terrestrial vegetation is an oft-cited objective of environmental flow recommendations, but there has been no systematic assessment of the evidence for and against the widely-accepted cause-and-effect mechanisms involved. We systematically reviewed the literature to test whether environmental flows can reduce the encroachment of terrestrial vegetation into river channels. We quantified the level of support for five explicit cause-effect hypotheses drawn from a conceptual model of the effects of flow on vegetation. We found that greater inundation, variously expressed as changes in the area, depth, duration, frequency, seasonality, and volume of surface water, generally reduces riparian vegetation abundance in channels, but most studies did not investigate the specific mechanisms causing these changes. Those that did show that increased inundation results in increased mortality, but also increased germination. The evidence was insufficient to determine whether increased inundation decreases reproduction. Our results contribute to hydro-ecological understanding by using the published literature to test for general cause-effect relationships between flow regime and terrestrial vegetation encroachment. Reviews of this nature provide robust support for flow management, and are more defensible than expert judgement-based approaches. Overall, we predict that restoration of more natural flow regimes will reduce encroachment of terrestrial vegetation into regulated river channels, partly through increased mortality. Conversely, infrequent deliveries of environmental flows may actually increase germination and subsequent encroachment.     

The role of hindrance stressors in the job demand–control–support model of occupational stress: A proposed theory revision

Previous research on the job demand–control–support (JDCS) model of occupational stress has generally been inconsistent at best regarding a key issue: the interaction of demands, control, and support in predicting employee health and well‐being. However, the model continues to be tested in a variety of studies and academic journals owing to its intuitive appeal. By incorporating conservation of resources theory with knowledge from the challenge–hindrance stressor framework, we proposed that hindrance stressors, not the challenge stressors commonly assessed when testing JDCS theory, will provide validation for the model. A two‐wave panel study of 228 employees in a variety of occupations provided support for three‐way interactions between hindrance demands, control, and support predicting job‐related anxiety and physical symptoms. Three‐way interactions using a challenge demand (forms of workload) were not significant, consistent with our propositions. In summary, this study supports the buffering effect of control and support on the relationship between job demands and strain only when job demands reflect hindrance stressors, thereby proposing to alter the JDCS model by specifying that it applies primarily to hindrance stressors in a job hindrance–control–support model. Copyright © 2015 John Wiley & Sons, Ltd.