Understanding “soil change” at the national scale, in addition to soil status, is a key challenge for national scale soil monitoring programs and is essential if more sustainable use of this finite resource is to be achieved. We present results from the first national scale survey of soil change to be reported three times within Europe and perhaps globally, covering a 30‐yr time span. Countryside Survey is an integrated national monitoring program that makes measurements of vegetation; topsoil physical, chemical, and biological characteristics (0–15 cm); water quality; and land use across Great Britain (GB), thus recognizing their interdependence. Here we report on change in fundamental soil chemical characteristics. Soil pH and loss on ignition (LOI) were measured in 1978, 1998, and 2007 and soil total nitrogen (total N) concentration and C/N ratio in 1998 and 2007. Bulk density was measured in 2007. Mean soil pH increased significantly in less acidic soils from 1978 through 1998 to 2007. Mean pH increased significantly in more acidic, organic‐rich soils from 1978 to 1998 but not between 1998 and 2007, indicating spatial trends in both sulfur deposition reductions and soil sensitivity. There was a small increase (8%) in GB topsoil C concentration (calculated from LOI) between 1978 and 1998, a small decrease (6.5%) between 1998 and 2007, and no significant overall change between 1978 and 2007. The unresolved difference between these results and those from the National Soil Inventory of England and Wales that reported wide‐scale large decreases in soil C concentrations in 2005 are discussed. There were unexpected small but significant decreases in total N concentration in many broad habitats despite continuing atmospheric nitrogen deposition. In seminatural and woodland habitats, this was accompanied by an increase in the C to N ratio, indicating one possible explanation is dilution of the nitrogen signal due to high C/N litter inputs resulting from increased primary productivity as reported elsewhere due to a range of global drivers such as increased CO 2 , N, and temperature. In arable systems, comparable rates of loss of C and N suggest erosion losses or deep plowing are reducing soil condition. The results are discussed in relation to the influences on soil processes of key drivers of environmental change and the importance of considering habitat‐specific trends.
Abstract. Volcanic emissions, specifically from Iceland, pose a pan-European risk and are on the UK National Risk Register due to potential impacts on aviation, public health, agriculture, the environment and the economy, from both effusive and explosive activity. During the 2014–2015 fissure eruption at Holuhraun in Iceland, the UK atmosphere was significantly perturbed. This study focuses one major incursion in September 2014, affecting the surface concentrations of both aerosols and gases across the UK, with sites in Scotland experiencing the highest sulfur dioxide (SO2) concentrations. The perturbation event observed was confirmed to originate from the fissure eruption using satellite data from GOME2B and the chemical transport model, EMEP4UK, which was used to establish the spatial distribution of the plume over the UK during the event of interest. At the two UK European Monitoring and Evaluation Program (EMEP) supersite observatories (Auchencorth Moss, SE Scotland, and Harwell, SE England) significant alterations in sulfate (SO42−) content of PM10 and PM2.5 during this event, concurrently with evidence of an increase in ultrafine aerosol most likely due to nucleation and growth of aerosol within the plume, were observed. At Auchencorth Moss, higher hydrochloric acid (HCl) concentrations during the September event (max = 1.21 µg m−3, cf. annual average 0.12 µg m−3 in 2013), were assessed to be due to acid displacement of chloride (Cl−) from sea salt (NaCl) to form HCl gas rather than due to primary emissions of HCl from Holuhraun. The gas and aerosol partitioning at Auchencorth Moss of inorganic species by thermodynamic modelling confirmed the observed partitioning of HCl. Using the data from the chemical thermodynamic model, ISORROPIA-II, there is evidence that the background aerosol, which is typically basic at this site, became acidic with an estimated pH of 3.8 during the peak of the event.Volcano plume episodes were periodically observed by the majority of the UK air quality monitoring networks during the first 4 months of the eruption (August–December 2014), at both hourly and monthly resolution. In the low-resolution networks, which provide monthly SO2 averages, concentrations were found to be significantly elevated at remote “clean” sites in NE Scotland and SW England, with record-high SO2 concentrations for some sites in September 2014. For sites which are regularly influenced by anthropogenic emissions, taking into account the underlying trends, the eruption led to statistically unremarkable SO2 concentrations (return probabilities > 0.1, ∼ 10 months). However, for a few sites, SO2 concentrations were clearly much higher than has been previously observed (return probability < 0.005, > 3000 months). The Holuhraun Icelandic eruption has resulted in a unique study providing direct evidence of atmospheric chemistry perturbation of both gases and aerosols in the UK background atmosphere. The measurements can be used to both challenge and verify existing atmospheric chemistry of volcano plumes, especially those originating from effusive eruptions, which have been underexplored due to limited observations available in the literature. If all European data sets were collated this would allow improved model verification and risk assessments for future volcanic eruptions of this type.
SUMMARY 32 P was used to determine phosphorus uptake by different mycorrhizas of birch in the field. Time of year and location of the application of 32 P were the dominant variables influencing uptake into the canopy. There was evidence of differential uptake by the three mycorrhizal types selected. Where Hebeloma mycorrhizas were more frequent, a significantly greater rate of phosphorus uptake per unit leaf weight occurred than where Laccaria or Lactarius were more frequent. The method shows potential for field evaluation of efficiency of nutrient uptake by mycorrhizas, although a number of factors need to be taken into account in determining uptake. In locating areas for 32 P injection, it was found that the distribution of mycorrhizal types on roots did not always reflect the distribution of the corresponding fruitbodies.
The nutritional requirements of Eucalyptusgrandis Hill ex Maiden seedlings were studied in glasshouse pot experiments. Nitrogen (N), phosphorus (P), and potassium (K) demand was assessed by bioassays, in which the uptake of tracers ( 15 N, 32 P, or 86 Rb) by roots excised from the seedlings grown at different levels of nutrient supply was measured. A pilot study showed that there was an inverse relationship between nutrient supply and influx. The measured influx was affected by the length of time that the roots were stored before the bioassay was applied. In a 3 3 N, P, and K factorial nutrient experiment, growth was primarily influenced by N. Maximum growth occurred at the highest level of supply of each of the three nutrients. N and K influx in the root bioassay was inversely related to foliar N and K concentration, but P uptake was not related to foliar P concentration. These results indicate that the root bioassays are more sensitive determinants of nutrient limitation than. foliar analysis. Interactions between N and P and between N and K alter the stem:leaf ratio, which may be of importance in optimizing wood production.
Abstract. Volcanic emissions, specifically from Iceland, pose a pan-European risk and are on the UK National Risk Register due to potential impacts on aviation, public health, agriculture, the environment and the economy, both from effusive and explosive activity. During the 2014–2015 fissure eruption of the Holuhraun in Iceland, the UK atmosphere was significantly perturbed. This study focuses on the first four months of the eruption (September to December 2014). During this period there was one major incursion in September 2014, affecting the surface concentrations of both aerosols and gases across the UK, with sites in Scotland experiencing the highest sulfur dioxide (SO2) concentrations. At the two UK EMEP supersite observatories (Auchencorth Moss, SE Scotland and Harwell, SE England) significant alterations in sulfate (SO42−) content of PM10 and PM2.5 during this event, concurrently with evidence of an increase in ultrafine aerosol, most likely due to nucleation and growth of aerosol within the plume, were observed. At Auchencorth Moss, higher hydrochloric acid (HCl) concentrations during the September event (max = 1.21 µg m−3, c.f annual average 0.12 µg m−3 in 2013), were assessed to be due to acid displacement of chloride (Cl−) from sea salt (NaCl) to form HCl gas rather than due to primary emissions HCl from Holuhraun. The gas and aerosol partioning at Auchencorth moss of inorganic species by thermodynamic modelling, confirmed the observed partioning of HCl. Volcano plume episodes were observed by the majority of the UK air quality monitoring networks during the first 4 months, at both hourly and monthly resolution. In the monthly networks, SO2 concentrations were significantly elevated at remote "clean" sites in NE Scotland and SW England, with record high SO2 concentrations for some sites. For sites which are regularly influenced by anthropogenic emissions, taking into account the underlying trends, the eruption led to statistically unremarkable SO2 concentrations (return probabilities > 0.1, ~ 10 months). However for a few sites, SO2 concentrations were clearly were much higher than has been previously observed (return probability < 0.005, > 3000 months). The Icelandic eruption has resulted in a unique study providing direct evidence of atmospheric chemistry perturbation of both gases and aerosols in the UK background atmosphere. The measurements can be used to both challenge and verify existing atmospheric chemistry of volcano plumes. If all European data sets were collated this would allow improved model verification and risk assessments for future volcanic eruptions.
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