A Relaxed Eddy Accumulation System for the Automated Measurement of Atmospheric Ammonia Fluxes

A continuous relaxed eddy accumulation system ispresented for the automated measurement of surface/atmosphere exchange fluxes of atmospheric ammonia (NH₃) at a single height. The new system features sampling by parallel plate denuder inlets, online chemical analysis using the conductivity cell of a commercially available NH₃ analyzer and online flux calculation. The effective detection limit of the system for air concentrations is 0.2 g m^-3 and it is estimated to resolve fluxes > ± 20 ng m^-2 s^-1, depending on the NH₃ concentration and turbulence. The performance of the system was tested in two measurement campaigns above agricultural grassland, in which it was compared with a 3-point continuous gradient system. During the first campaign, after urea application of 47 kg N ha^-1 in autumn, the REA system derived fluxes which were on average twice as large as the gradient fluxes, while concentrations agreed closely (on average within 4%). Possible reasons include differences in the footprint and an over-correction of the gradient flux in stable conditions. Due to wet and cold conditions, only 0.3% of the fertilizer N was volatilized as NH₃ during the first week. Results from the deployment of an improved system are presented for a summer day, 6 days after fertilization with calcium ammonium nitrate. The agreement of both concentrations (on average within 13%) and fluxes (26%) was very encouraging and similar to the agreement found between two state-of-the-art gradient systems with online analysis.     

The potential for spatial planning at the landscape level to mitigate the effects of atmospheric ammonia deposition

Ammonia (NH₃) is emitted mainly from agricultural practices, with NH₃ concentrations decreasing rapidly away from sources. As a consequence there is a high spatial variability in nitrogen deposition and its consequent ecological effects in agricultural landscapes that is in addition to differences in sensitivity between habitat types. This variability points to the potential to include spatial planning measures as part of strategies to protect sensitive vegetation from ammonia deposition.National abatement policies typically include uniform recommendations for technical abatement measures, such as ploughing in manures after land spreading. In this study, the complementary potential of spatial planning to reduce effects on target locations is analysed through model scenarios for an example landscape in central England. Scenarios included defining buffer zones of low-emission agriculture and establishing tree belts surrounding either emission sources or priority areas for the protection of semi-natural habitats.The analysis showed that tree belts can reduce deposition to sensitive areas, with trees surrounding the sensitive habitats being more effective than trees around the sources. Low emission buffer zones around sink areas also result in useful reductions in N deposition. Smaller nature reserve sites benefit to a greater degree from such spatial planning measures, as large reserves can provide their own buffer zone to some degree. Similarly, relocating point sources or using planning policies to ensure the location of large NH₃ point sources are at least 2–3 km from the sensitive habitats results in substantial reductions in N deposition.     

A case of a paracentric inversion inv(7)(q11q22). Prenatal detection and counselling

A paracentric inversion in the long arm of a number 7 chromosome was detected in an amniotic cell culture from a 41 year old woman, screened because of maternal age. The karyotype was 46, XX, inv(7) (q11q22). Her husband carried an identical inversion. The parents were advised that the pregnancy should continue and a healthy infant was born at term. Prenatal diagnosis and counselling for paracentric inversion heterozygotes are discussed in the light of published and unpublished cases.     

Microbial metabolic activities in soils of old-field communities following eleven years of nutrient enrichment

Effects of 11 years (1978-1988) of nutrient enrichment (fertilizer or sludge) on microbial metabolic activity in soil samples collected from contrasting types of old-field communities were studied during September 1989. During the 1989 growing season, subplots were manipulated by tilling and/or liming to evaluate mechanisms of ecosystem recovery or were left undisturbed. Metabolic activities of soil microorganisms were determined by measuring dehydrogenase activity within soil samples collected from these subplots. The amounts of 2,3,5-triphenyltetrazolium formazan formed during incubation by the reduction of 2,3,5-triphenyltetrazolium chloride were used to evaluate dehydrogenase activity. Plots that had received long-term applications of sludge or fertilizer had significantly lower rates of microbial activity (P<0.05) than did control plots. Fertilizer and sludge plots treated with lime had significantly higher microbial metabolic activity (P<0.05) than those not receiving lime. Whereas liming stimulated microbial activity to near control levels, tilling had no significant treatment effect.     

Nitrate toxicity toPenaeus monodon protozoea

Increased levels of nitrate occur in natural waters due to pollution, and in aquaculture systems from nitrification and addition of microalgal cultures for feeding. Static bioassays showed that significant mortality of larvalPenaeus monodon (Fabricius) occurred within 40 h at nitrate concentrations as low as 1 mg NO ₃ ^- l^–1. Sublethal effects of this concentration resulted in changes to ganglionic neuropiles and muscles. At higher concentrations (10 and 100 mg NO ₃ ^- l^–1), additional tissues were affected including the hypodermis, midgut and proventriculus. This is the first report of toxicity to a marine organism of nitrate at concentrations normally present in enclosed seawater and mariculture systems. The results are discussed in terms of management of culture systems and of natural marine ecosystems containing elevated levels of nitrate.     

Old distribution procedure of both water and matter fluxes in floodplains of western Europe: Impact on present vegetation

In France and the United States it has been shown that strong linkages exist between vegetation and alluvial landforms within homogeneous river stretches characterized by geomorphological processes, flood duration, flood magnitude, flood frequency, and sediment size. Furthermore, perturbations induced by man (such as embankments and damming) have been shown to have an effect on both succession and plant distribution patterns. Yet, in numerous cases it is not possible to find either the communities or the plants whose presence might be predicted by reference to the river section characteristics (such as straight, braided, anastomosed, or meandering channels) or by reference to perturbation effects well known in piedmont valleys (such as variations of the water-table depth, variations of magnitude, and frequency and duration of floods). Unexpected species, new communities, and even new successional sequences are often observed. The presence of new alluvial forms explains these differences. An “artificial” substratum generated by an old human perturbation (limited in the time) has been established in the past; consequently, the natural distribution patterns of water and matter flows have been disturbed. Archive research has enabled a classification of abandoned systems that were commonly used during the 16th, 17th, 18th, and 19th centuries on European floodplains. Several case studies were chosen in order to illustrate and explain the importance of stream corridor history. The example of the Isère River valley, downstream from Albertville, is chosen to highlight the heterogeneity of the vegetation mosaïc pattern outside the dikes. The historical reconstruction explains the role of the additional disturbances that cause deviation from the system evolution patterns.     

Ecological literacy and socio-demographics: who are the most eco-literate in our community,and why?

Ecological literacy is founded upon knowledge and understanding about how the ecological systems of the Earth function and support life. A widespread concern that levels of ecological literacy within many contemporary human communities are inadequate to enable effective decision-making about sustainable ways of living led to a rigorous and carefully designed assessment of over 1000 South Australian adults from diverse sectors including industry, government, nongovernment, business and community organisations. This assessment tested for local and global knowledge, including an understanding of the interconnection of natural systems with human society. Quantitative analyses revealed significant relationships between scores and a range of socio-demographic characteristics. Scores varied significantly with gender, age, education, employment, place of growing up and time spent in South Australia (SA). Highest average scores were found in males, middle-age groups, the most highly educated, those with science-related educational backgrounds, those working in environment-related fields, those who grew up in small town environments rather than in large towns or cities and in those who had spent more than 10 years in SA. These findings contribute to a broader study of factors associated with ecologically literate individuals and groups within the western and industrialised adult community of SA. They form a valuable foundation on which to build efforts to further understand and develop ecological literacy within our citizenry and governing bodies.     

A New Diffusion Denuder System for Long-Term,Regional Monitoring of Atmospheric Ammonia and Ammonium

Estimating regional patterns in concentrations of atmosphericammonia (NH₃) gas and ammonium (NH₄ ⁺) in aerosolis essential to assess dry deposition, as well as to test theperformance of long-range transport models. Until now, methods for monitoring NH₃ and NH₄ ⁺ (collectively NH_x) have focused on either passive sampling, which does not sample aerosol NH₄ ⁺, or active sampling techniquessuitable for sampling over several minutes to 24 hr. The classicalactive sampling approach is the diffusion denuder, which typically involves either a complex annular denuder or a long(0.5 m) and fragile glass tube. A new denuder implementationis reported here that has been designed for long-term samplingof NH₃ and NH₄ ⁺. By sampling at just 0.35 L min^-1, the method is suitable for monthly measurementsand uses 0.1 m long glass denuders, which may be sent safelyby the normal postal service to monitoring sites. Two denudersare applied in series to test for adequate NH₃ captureefficiency in each sample, while a subsequent acidified paperfilter collects NH₄ ⁺. The method has been implementedat over 50 sites across the U.K. as part of a new national monitoring network. The detection limit is <0.01 μg m^-3 and the sampling is sufficiently accurate to show theseasonal patterns at different sites. This low-cost method willbe useful to address future trends in NH₃ and NH₄ ⁺, especially in relation to compliance with international agreements to reduce NH₃ emissions.     

Statistical evaluation of data from multi-laboratory testing of a measurement method intended to indicate the presence of dust resulting from the collapse of the World Trade Center

In this paper we describe a statistical analysis of the inter-laboratory data summarized in Rosati et al. (2008) to assess the performance of an analytical method to detect the presence of dust from the collapse of the World Trade Center (WTC) on September 11, 2001. The focus of the inter-lab study was the measurement of the concentration of slag wool fibers in dust which was considered to be an indicator of WTC dust. Eight labs were provided with two blinded samples each of three batches of dust that varied in slag wool concentration. Analysis of the data revealed that three of labs, which did not meet measurement quality objectives set forth prior to the experimental work, were statistically distinguishable from the five labs that did meet the quality objectives. The five labs, as a group, demonstrated better measurement capability although their ability to distinguish between the batches was somewhat mixed. This work provides important insights for the planning and implementation of future studies involving examination of dust samples for physical contaminants. This work demonstrates (a) the importance of controlling the amount of dust analyzed, (b) the need to take additional replicates to improve count estimates, and (c) the need to address issues related to the execution of the analytical methodology to ensure all labs meet the measurement quality objectives.