Transient secondary currents behind a compression wave in an irregular channel

Environmental Fluid Mechanics - A compression wave is an unsteady rapidly-varied open channel flow motion, characterised by an increase in water depth. A detailed investigation was conducted in a...     

A Device for Measuring Volatile Organic-Carbon Emissions from Cooling-Tower Water

A manual method for measuring reduced sulfur compounds in kraft pulp mill and sulfur recovery plant emissions was evaluated. The method involves removing SO₂ from the gas stream (if present) with a citric acid-potassium citrate buffer that passes reduced sulfur compounds; thermal oxidation of all reduced sulfur compounds to SO₂; collection of the SO₂ in H₂O₂; and a titrimetric analysis of the H₂O₂ for SO₄ ^2?. A heated filter removes alkaline particulate matter that would produce a negative interference if absorbed by the buffer. When used at kraft pulp mills, the method agrees closely with Reference Method 16, provided that nonregulated reduced sulfur compounds, such as carbonyl sulfide, are not present in the emissions. At sulfur recovery plants, nonregulated reduced sulfur compounds, such as thiophene, are likely to be present in the emissions and will produce a positive bias in the results obtained with this method. The precision of the method ranges from 1 to 7 percent relative standard deviation.     

Field Validation of a Conservation Network on the Eastern Shore of Maryland,USA, Using Breeding Birds as Bio-Indicators

Maryland’s Green Infrastructure (GI) is a network of large, intact natural areas (hubs), interconnected by linear swaths of riparian or upland vegetation (corridors). The GI serves significant ecological functions and provides the bulk of the state’s natural support system. This study examined whether the GI as mapped does, in fact, identify Maryland’s most ecologically valuable forested lands, using forest interior dwelling birds (hereafter called “forest birds”) as bio-indicators. We conducted bird point counts within forest both inside and outside of hubs on Maryland’s Eastern Shore. We also collected a wide variety of habitat data. We found that both the condition of a forest and its surrounding landscape influenced the bird communities. On average, forest bird richness was significantly higher within hubs; furthermore, almost all sites with at least five forest bird species present were in hubs. Forest bird richness and abundance were highest in undisturbed, mature broadleaf forest with wetlands and streams nearby. We detected a significant relationship between forest bird richness and the ecological score of a finer-scale landscape assessment, focused on “cells” of about 0.1 ha in size. This field study also validated the Rapid Field Assessment (RFA) protocol developed in 2001 to assess, on the ground, the relative condition of individual sites or properties within the GI. Forest bird richness and abundance were positively correlated with the RFA community scores. Our results underscore the importance of maintaining regional biological diversity by retaining large blocks of forest, especially mature forest containing streams and wetlands.     

Distribution and ecotoxicity of chlorotriazines in the Scheldt Estuary (B-Nl)

As part of the Endis-Risks project, the current study describes the occurrence of the chlorotriazine pesticides atrazine, simazine and terbutylazine in water, sediment and suspended matter in the Scheldt estuary (B-Nl) from 2002 to 2005 (3 samplings a year, 8 sampling points). Atrazine was found at the highest concentrations, varying from 10 to 736 ng/l in water and from 5 up to 10 ng/g in suspended matter. Simazine and terbutylazine were detected at lower concentrations. Traces of the targeted pesticides were also detected in sediments, but these were below the limit of quantification. As part of an ecotoxicological assessment, we studied the potential effect of atrazine on molting of Neomysis integer (Crustacea:Mysidacea), a resident invertebrate of the Scheldt Estuary and a proposed test organism for the evaluation of endocrine disruption. Following chronic exposure ( approximately 3 weeks), atrazine did not significantly affect mysid molting at environmentally relevant concentrations (up to 1 microg/l).     

The effect of increasing lifespan and recycling rate on carbon storage in wood products from theoretical model to application for the European wood sector

The use of wood products is often promoted as a climate change mitigation option to reduce atmospheric carbon dioxide concentrations. In previous literature, we identified longevity and recycling rate as two determining factors that influence the carbon stock in wood products, but no studies have predicted the effect of improved wood use on carbon storage over time. In this study, we aimed at evaluating changes in the lifespan and the recycling rate as two options for enhancing carbon stock in wood products for different time horizons. We first explored the behaviour over time of both factors in a theoretical simulation, and then calculated their effect for the European wood sector of the future. The theoretical simulation shows that the carbon stock in wood products increases linearly when increasing the average lifespan of wood products and exponentially when improving the recycling rate. The emissions savings under the current use of wood products in Europe in 2030 were estimated at 57.65 Mt carbon dioxide (CO₂) per year. This amount could be increased 5 Mt CO₂ if average lifespan increased 19.54 % or if recycling rate increased 20.92 % in 2017. However, the combination of both strategies could increase the emissions saving almost 5 Mt CO₂ more by 2030. Incrementing recycling rate of paper and paperboard is the best short-term strategy (2030) to reduce emissions, but elongating average lifespan of wood-based panels is a better strategy for longer term periods (2046).