Rain and cloud water from a high-elevation site and an adjacent lower-level site in the northern Pennines of England were sampled and analysed between 1994 and 2008. The comparison of wet deposition ...and rainfall depth at the high and low-level sites has been used to estimate the additional deposition of pollutants arising from ‘seeder–feeder’ enhancement by washout of the orographic cap cloud that forms over the high-level site. The derived ‘orographic scavenging ratio’ for different ions is used to map the orographic enhancement of wet deposition across the U.K. The ratio of ion concentrations in cloud and in rain at the high-level site is also important for estimating the input of pollutants through the direct capture of cloud water droplets at high elevation sites.
Long-term trends in ion concentrations in cloud and rain showed significant downward trends in non-sea sulphate, and a weaker downward trend in nitrate, but no trend in other ions. There was also no trend in the orographic scavenging ratios, implying that the methods used to estimate orographic enhancement across the U.K. are robust over time.
•Cloud and rain water analysis from low and high elevation sites in Pennines, UK•Orographic (seeder–feeder) enhancement of cloud ion concentrations estimated•Long-term (1994–2008) downward trends in non-sea sulphate and nitrate•No trends in cloud:rain scavenging ratios, implying consistent mechanism•Uncertainties in extrapolation to upland UK are quantified.
The assessment of the deposition of both wet (rain and cloud) and dry sedimenting particles is a prerequisite for estimating element fluxes in ecosystem research. Many nations and institutions ...operate deposition networks using different types of sampler. However, these samplers have rarely been characterized with respect to their sink properties. Major errors in assessing bulk deposition can result from poor sampling properties and defective sampling strategies. Relevant properties are: sampler geometry and material, in particular the shape of the rim; sink properties for gases and aerosols; and microbial transformations of the collected samples. An adequate number of replicates allows the identification of samples which are contaminated, in particular by bird droppings. The paper discusses physical and chemical properties of the samplers themselves. The dependence of measurement accuracy on the number of replicates and the sampling area exposed is discussed. Recommendations are given for sampling strategies, and for making corrections and substitution of missing data.
Recommendations are given for sampling strategies and for making corrections and substitution of missing data.
Robust emission inventories of atmospheric pollutants are critical to understanding and predicting impacts, identifying key sources and mitigation opportunities. The objective of this study was to ...review the extent to which UK land management is accounted for as a source of emission of ammonia (NH
3), nitrous oxide (N
2O), nitrogen oxides (NO
x), organic nitrogen (N
org), methane (CH
4), non-methane volatile organic compounds (NMVOC), particulate matter (PM) and heavy metals (HM), in comparison with the current state of scientific knowledge; to ascertain whether there is evidence for significant gaps or that key emission sources have been overlooked. The processes leading to emissions of NH
3, N
2O and CH
4 are largely understood and all major sources are thought to be captured in the current inventory. Quantification of uncertainties in the estimates for some of these sources is still required, as is an assessment of the potential improvement in accuracy of estimates through the development of country-specific emission factors for N
2O and CH
4 in particular. There is limited knowledge about sources and processes leading to emissions of N
org and the role that these may play in local and global nitrogen budgets. Land management is known to be a source of NO
x, NMVOC and PM emissions, and potentially also HM emissions. Improved quantification is required to assess the importance of land management as a source of these pollutants in comparison with other sectors and, if appropriate, to determine the potential for mitigation.
► Major emission sources of NH
3, N
2O and CH
4 from land management are accounted. ► The importance of land management for NO
x, NMVOC and PM emissions is less certain. ► Emissions of organic nitrogen and their role in the atmosphere is poorly understood. ► Better quantification of the uncertainty in pollutant emission estimates is needed.
Background and objective Critical care transport (CCT) involves the movement of critically ill patients between healthcare facilities. South Africa (SA), like other low- to middle-income countries, ...has a relative shortage of ICU beds, making CCT an inevitability. In SA, CCTs are mostly done by emergency care practitioners; however, it is unclear how universities offering Bachelor in Emergency Medical Care (BEMC) courses approach their teaching in critical care and whether the content taught is consistent between institutions. In our study we formally evaluate and compare the intensive and critical care transport modules offered at SA universities in their BEMC programmes.Methods The electronic version of curricula of the critical care transport modules from higher education institutes in SA offering the BEMC were subjected to document analysis. Qualitative (inductive content analysis) and quantitative (descriptive analysis) methods were used to describe and compare the different components of the curriculum. Curricula were assigned into components and sub-components according to accepted definitions of curricula. The components included: aims, goals, composition and objectives of the course; content or teaching material and work-integrated learning.Results The four universities that offer BEMC programmes were invited to participate, and three (75%) consented and provided data. The duration of the modules ranged from 6 to 12 months, corresponding with notional hours of 120 - 150. A total of 83 learning domains were generated from the coding process. These domains included content on mechanical ventilation, patient monitoring, arterial blood gases, infusions and fluid balance, and patient preparation and transfer. Two universities had identical structures and learning outcomes, while one had a different structure and outcomes; it corresponded with a 58% similarity. Clinical placements were in critical and emergency care units, operating theatres and prehospital clinical services.Conclusion In all components compared, the universities offering BEMC were more similar than they were different. It is unclear whether the components taught are relevant to the SA patient population and healthcare system context, or whether students are adequately prepared for clinical practice. Postgraduate educational programmes might need to be developed to equip emergency care practitioners to function in this environment safely.
A comprehensive European dataset on monthly atmospheric NH3, acid gases (HNO3, SO2, HCl), and aerosols (NH4+, NO3-, SO42-, Cl-, Na+, Ca2+, Mg2+) is presented and analysed. Speciated measurements were ...made with a low-volume denuder and filter pack method (DEnuder for Long-Term Atmospheric sampling, DELTA®) as part of the EU NitroEurope (NEU) integrated project. Altogether, there were 64 sites in 20 countries (2006–2010), coordinated between seven European laboratories. Bulk wet-deposition measurements were carried out at 16 co-located sites (2008–2010). Inter-comparisons of chemical analysis and DELTA® measurements allowed an assessment of comparability between laboratories.The form and concentrations of the different gas and aerosol components measured varied between individual sites and grouped sites according to country, European regions, and four main ecosystem types (crops, grassland, forests, and semi-natural). The smallest concentrations (with the exception of SO42- and Na+) were in northern Europe (Scandinavia), with broad elevations of all components across other regions. SO2 concentrations were highest in central and eastern Europe, with larger SO2 emissions, but particulate SO42- concentrations were more homogeneous between regions. Gas-phase NH3 was the most abundant single measured component at the majority of sites, with the largest variability in concentrations across the network. The largest concentrations of NH3, NH4+, and NO3- were at cropland sites in intensively managed agricultural areas (e.g. Borgo Cioffi in Italy), and the smallest were at remote semi-natural and forest sites (e.g. Lompolojänkkä, Finland), highlighting the potential for NH3 to drive the formation of both NH4+ and NO3- aerosol. In the aerosol phase, NH4+ was highly correlated with both NO3- and SO42-, with a near-1:1 relationship between the equivalent concentrations of NH4+ and sum (NO3-+ SO42-), of which around 60 % was as NH4NO3.Distinct seasonality was also observed in the data, influenced by changes in emissions, chemical interactions, and the influence of meteorology on partitioning between the main inorganic gases and aerosol species. Springtime maxima in NH3 were attributed to the main period of manure spreading, while the peak in summer and trough in winter were linked to the influence of temperature and rainfall on emissions, deposition, and gas–aerosol-phase equilibrium. Seasonality in SO2 was mainly driven by emissions (combustion), with concentrations peaking in winter, except in southern Europe, where the peak occurred in summer. Particulate SO42- showed large peaks in concentrations in summer in southern and eastern Europe, contrasting with much smaller peaks occurring in early spring in other regions. The peaks in particulate SO42- coincided with peaks in NH3 concentrations, attributed to the formation of the stable (NH4)2SO4. HNO3 concentrations were more complex, related to traffic and industrial emissions, photochemistry, and HNO3:NH4NO3 partitioning. While HNO3 concentrations were seen to peak in the summer in eastern and southern Europe (increased photochemistry), the absence of a spring peak in HNO3 in all regions may be explained by the depletion of HNO3 through reaction with surplus NH3 to form the semi-volatile aerosol NH4NO3. Cooler, wetter conditions in early spring favour the formation and persistence of NH4NO3 in the aerosol phase, consistent with the higher springtime concentrations of NH4+ and NO3-. The seasonal profile of NO3- was mirrored by NH4+, illustrating the influence of gas–aerosol partitioning of NH4NO3 in the seasonality of these components.Gas-phase NH3 and aerosol NH4NO3 were the dominant species in the total inorganic gas and aerosol species measured in the NEU network. With the current and projected trends in SO2, NOx, and NH3 emissions, concentrations of NH3 and NH4NO3 can be expected to continue to dominate the inorganic pollution load over the next decades, especially NH3, which is linked to substantial exceedances of ecological thresholds across Europe. The shift from (NH4)2SO4 to an atmosphere more abundant in NH4NO3 is expected to maintain a larger fraction of reactive N in the gas phase by partitioning to NH3 and HNO3 in warm weather, while NH4NO3 continues to contribute to exceedances of air quality limits for PM2.5.
Throughfall chemistry was studied in a mature Sitka spruce plantation in order to investigate canopy interactions, such as nitrogen absorption, cation leaching, and neutralization of rainfall passing ...through the canopy. The plantation had been exposed to six different simulated mist treatments including N (NH
4NO
3) and S (H
2SO
4 at pH 2.5) in four replicated blocks since 1996. Throughfall and rainfall were collected from May to September 2000. The results showed that 30–35% of the applied N was retained by the canopy. There were linear relationships between the loss of H
+ and increased K
+, Mg
2+ and Ca
2+ deposition through the canopy. However these increases in K
+, Mg
2+ and Ca
2+ deposition accounted for only about 50% of total neutralization of the acidity. The relationship between the anion deficits in throughfall and the loss of H
+ implied that weak organic acid anions were involved in the neutralization of the acidity in throughfall.
Weak organic acids may be involved in neutralizing acidity of throughfall.
1. Atlantic bryophytes are of European conservation importance, yet the effect on them of excess atmospheric nitrogen is relatively unknown. This study assesses the effects of increased atmospheric N ...deposition on the growth and tissue N of epiphytic Atlantic bryophytes, and their potential to recover following a decline in N deposition. 2. The N received in stemflow by bryophytes at two sites was measured and compared to model predictions. 3. Four species of epiphytic bryophytes (Isothecium myosuroides, Dicranum scoparium, Frullania tamarisci and Ulota crispa), typical of Atlantic Oak woods, were studied in a 12-month reciprocal transplant experiment between a pristine Oak woodland receiving a modelled atmospheric deposition of 12 kg N ha-1year-1and a polluted one receiving 54 kg N ha-1year-1. 4. Tissue N concentration increased and growth declined following an increase in atmospheric N deposition in all species except Ulota crispa. Conversely, tissue N concentration decreased and growth increased in Frullania tamarisci following a decrease in atmospheric N deposition, with similar non-significant patterns in the other species. 5. The reciprocal transplants indicate a detrimental effect of increased N deposition on the bryophyte species studied. The study indicated recovery following a decrease in atmospheric N deposition, but the responses caused by decreased N deposition were smaller than those due to increased N deposition. This suggests that the time-scale for recovery of bryophytes from excess N deposition is longer than the timescale of nitrogen impacts.
Total gaseous mercury (TGM) was monitored during 2013 at the rural monitoring site, Harwell, England using the Tekran 2537A monitoring system. Average TGM for the year was 1.45 ± 0.24 ng m(-3). This ...is comparable to other northern hemisphere studies, but on average 0.5 ng m(-3) higher than at its sister monitoring station at Auchencorth Moss, Scotland, but 14% lower than that found in a similar study at the same location of 1.68 ng m(-3) in 1995/6. Using wind sector analysis we show the important influence of local emissions, with our data showing that the largest influence on TGM observed is that of the adjacent Science & Innovation campus, making the site more a 'suburban background'. By using co-located measurements of black carbon and sulphur dioxide as tracers, we present an initial investigation into the impact of the closure of Didcot A coal fired power station, which ceased operating in March 2013. Further analysis using air mass back trajectories shows the long-range contribution to TGM from continental Europe, and that the lowest levels are associated with marine air masses from the west.
Previous work has indicated that the soil is important to understanding biogeochemical fluxes of trichloroacetic acid (TCA) in the rural environment, in forests in particular. Here, the hydrological ...and TCA fluxes through 22
in situ soil columns in a forest and moorland-covered catchment and an agricultural grassland field in Scotland were monitored every 2
weeks for several months either as controls or in TCA manipulation (artificial dosing) experiments. This was supplemented by laboratory experiments with radioactively-labelled TCA and with irradiated (sterilised) soil columns. Control
in situ forest soil columns showed evidence of net export (i.e.
in situ production) of TCA, consistent with a net soil TCA production inferred from forest-scale mass balance estimations. At the same time, there was also clear evidence of substantial
in situ degradation within the soil (∼70% on average) of applied TCA. The laboratory experiments showed that both the formation and degradation processes operate on time scales of up to a few days and appeared related more with biological rather than abiotic processes. Soil TCA activity was greater in more organic-rich soils, particularly within forests, and there was strong correlation between TCA and soil biomass carbon content. Overall it appears that TCA soil processes exemplify the substantial natural biogeochemical cycling of chlorine within soils, independent of any anthropogenic chlorine flux.
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