An uncertainty analysis of mean flow velocity measurements used to quantify emissions from stationary sources

Point velocity measurements conducted by traversing a Pitot tube across the cross section of a flow conduit continue to be the standard practice for evaluating the accuracy of continuous flow-monitoring devices. Such velocity traverses were conducted in the exhaust duct of a reduced-scale analog of a stationary source, and mean flow velocity was computed using several common integration techniques. Sources of random and systematic measurement uncertainty were identified and applied in the uncertainty analysis. When applicable, the minimum requirements of the standard test methods were used to estimate measurement uncertainty due to random sources. Estimates of the systematic measurement uncertainty due to discretized measurements of the asymmetric flow field were determined by simulating point velocity traverse measurements in a flow distribution generated using computational fluid dynamics. For the evaluated flow system, estimates of relative expanded uncertainty for the mean flow velocity ranged from ±1.4% to ±9.3% and depended on the number of measurement locations and the method of integration.

Implications:Accurate flow measurements in smokestacks are critical for quantifying the levels of greenhouse gas emissions from fossil-fuel-burning power plants, the largest emitters of carbon dioxide. A systematic uncertainty analysis is necessary to evaluate the accuracy of these measurements. This study demonstrates such an analysis and its application to identify specific measurement components and procedures needing focused attention to improve the accuracy of mean flow velocity measurements in smokestacks.     

Unique phenotypes in the sperm of the earthworm Eudrilus eugeniae for assessing radiation hazards

The earthworm, Eudrilus eugeniae is a segmented worm. It has two pairs of testes whose cells are highly proliferative. It was found that the earthworm, which is irradiated with X-ray, shows the following phenotypic changes in its sperm: fragmented acrosome in the head, break in the tail, and the appearance of zigzag sperm tail. Sperm morphology can be used as a tool to study radiation hazards in local areas. These three phenotypes were not observed in the sperm of worms exposed to different concentration of toxic chemicals such as sodium arsenate, lead acetate, and mercuric chloride. In contrast, exposure of worms to ethidium bromide caused fragmented acrosome in the head of their sperm cells.     

Effects of suburban land use on phosphorus fractions and speciation in the Upper Peruque Creek, Eastern Missouri

This field study was conducted to explore the spatial and seasonal changes in total phosphorus and fraction distribution in relation to land uses. Water samples were collected biweekly at four sampling locations, which represented different potential phosphorus sources along the Upper Peruque Creek in Eastern Missouri. Total phosphorus concentrations of > 0.8 mg/L appeared sporadically at site 2, downstream of a small community, with an average of 0.82 +/- 0.14 mg/L in fall. Particulate phosphorus accounted for approximately 80% of total phosphorus at all sampling sites, except for site 2, where approximately 50 to 75% of dissolved phosphorus was often observed. Approximately 71 and 85% of total phosphorus in the sediment was in the form of iron (III) phosphate at the headwaters and downstream sites, respectively; 29 and 15% was in the form of phytic acid at the two sites. Land uses affect the total phosphorus concentration and alternate phosphorus fraction and speciation in the creek.     

Influences of Water and Sediment Quality and Hydrologic Processes on Mussels in the Clinch River

Segments of the Clinch River in Virginia have experienced declining freshwater mussel populations during the past 40 years, while other segments of the river continue to support some of the richest mussel communities in the country. The close proximity of these contrasting reaches provides a study area where differences in climate, hydrology, and historic mussel distribution are minimal. The USGS conducted a study between 2009 and 2011 to evaluate possible causes of the mussel declines. Evaluation of mussel habitat showed no differences in physical habitat quality, leaving water and sediment quality as possible causes for declines. Three years of continuous water‐quality data showed higher turbidity and specific conductance in the reaches with low‐quality mussel assemblages compared to reaches with high‐quality mussel assemblages. Discrete water‐quality samples showed higher major ions and metals concentrations in the low‐quality reach. Base‐flow samples contained high major ion and metal concentrations coincident to low‐quality mussel populations. These results support a conceptual model of dilution and augmentation where increased concentrations of major ions and other dissolved constituents from mined tributaries result in reaches with declining mussel populations. Tributaries from unmined basins provide water with low concentrations of dissolved constituents, diluting reaches of the Clinch River where high‐quality mussel populations occur.     

Achieving public participation in coastal zone environmental impact assessment

The case is made in this paper for early and integrative public participation in planning decisions concerning proposals major development in the zone. This is perhaps easy to subscribe to in theory but much more difficult in practice. Currently the extent and timing of public involvement in such decisions varies widely. A key benefit is the legitimacy that public participation provides to the planning process and, perhaps as a result, a variety of public involvement methodologies have emerged. Important considerations include which sections of the public to involve and at what stage in the decision-making process to involve them. The multidisciplinary nature of coastla zone issues will tend to engage a wide variety of stakeholder groups who in turn will influence the topics for discussion. A major port expansion proposal in the UK is used to illustrate a range of ways in which the public can be involved. The case study also highlights that public participation is an uncertain science, and to be successful can require skilled personnel and significant resources. The papper concludes that more guidance for developers, some standardisation of public involvement, training for facilitatiors and a more responsible stance from some environmental pressure groups would be advantageous. The complexity of coastal decision-making, tensions between science and policy, and the inter-dependency of coastal activities mutually reinforce the view that inclusive participation is an important issue for all coastal communities.     

Correlates of bushmeat in markets and depletion of wildlife

We used data on number of carcasses of wildlife species sold in 79 bushmeat markets in a region of Nigeria and Cameroon to assess whether species composition of a market could be explained by anthropogenic pressures and environmental variables around each market. More than 45 mammal species from 9 orders were traded across all markets; mostly ungulates and rodents. For each market, we determined median body mass, species diversity (game diversity), and taxa that were principal contributors to the total number of carcasses for sale (game dominance). Human population density in surrounding areas was significantly and negatively related to the percentage ungulates and primates sold in markets and significantly and positively related to the proportion of rodents. The proportion of carnivores sold was higher in markets with high human population densities. Proportion of small‐bodied mammals (<1 kg) sold in markets increased as human population density increased, but proportion of large‐bodied mammals (>10 kg) decreased as human population density increased. We calculated an index of game depletion (GDI) for each market from the sum of the total number of carcasses traded per annum and species, weighted by the intrinsic rate of natural increase (r_max) of each species, divided by individuals traded in a market. The GDI of a market increased as the proportion of fast‐reproducing species (highest r_max) increased and as the representation of species with lowest r_max (slow‐reproducing) decreased. The best explanatory factor for a market's GDI was anthropogenic pressure—road density, human settlements with >3000 inhabitants, and nonforest vegetation. High and low GDI were significantly differentiated by human density and human settlements with >3000 inhabitants. Our results provided empirical evidence that human activity is correlated with more depleted bushmeat faunas and can be used as a proxy to determine areas in need of conservation action.