Effects of soil fluoride pollution on wheat growth and biomass production, leaf injury index, powdery mildew infestation and trace metal uptake.

Fluoride (F) is an emerging pollutant that originates from multiple sources and adversely affects plant growth and nutrient bioavailability in soil. This greenhouse study investigated the effects of soil F (0, 10, 20, 50, 100, 200 mg kg-1) on morpho-physiological growth characteristics of wheat, soil F contents, and bioavailability and uptake of F, phosphorus (P), sulphur (S), potassium (K), calcium (Ca), magnesium (Mg), aluminium (Al), iron (Fe), manganese (Mn), silicon (Si) and zinc (Zn) by wheat. Higher F significantly reduced plant height and number of leaves particularly at early growth stages and increased visible leaf injury index. Powdery mildew infestation coincided with leafy injury and was higher in elevated soil F treatments. Fluoride treatments (>50 mg kg-1) significantly increased water (H2O)- and calcium chloride (CaCl2)-extractable F contents in soil. Water-extractable soil F contents from soil in all concentration were higher than CaCl2-extractable F. This increased F bioavailability resulted in significantly higher F uptake and accumulation in live leaves, dead leaves and grains of wheat which followed order: live leaves > dead leaves > grains. Leaf injury index and number of dead leaves correlated significantly positively with soil H2O- and CaCl2-extractable F contents. Patterns of nutrient (P, K, S) and trace metals (Al, Ca, Mg, Fe, Mn, Si, Zn) varied significantly with F concentrations and between live and dead leaves, and grains except for Zn. Dead leaves generally had higher nutrients and trace metals than live leaves and grains. Fluoride contents in live leaves, dead leaves and grains showed positive correlations with nutrient elements but negative with trace metals. Number of dead leaves correlated negatively with Al, Ca, Fe, Mg, S and Si but positively with P and Zn contents in dead leaves whereas leaf injury index showed positive correlation with Fe, K, P, Si, Zn, S but negative with Al, Ca and Mg contents. These observations provided evidence of higher F uptake and associated impairment in nutrient and trace metal accumulation which caused leaf injury accompanied by powdery mildew infestation in wheat. However, further research in the region is required to confirm the relationship between F pollution, leaf injury and trace metal accumulation in crops under field conditions.

Development of the Low Emissions Analysis Platform - Integrated Benefits Calculator (LEAP-IBC) tool to assess air quality and climate co-benefits: Application for Bangladesh.

Low- and middle-income countries have the largest health burdens associated with air pollution exposure, and are particularly vulnerable to climate change impacts. Substantial opportunities have been identified to simultaneously improve air quality and mitigate climate change due to overlapping sources of greenhouse gas and air pollutant emissions and because a subset of pollutants, short-lived climate pollutants (SLCPs), directly contribute to both impacts. However, planners in low- and middle-income countries often lack practical tools to quantify the air pollution and climate change impacts of different policies and measures. This paper presents a modelling framework implemented in the Low Emissions Analysis Platform - Integrated Benefits Calculator (LEAP-IBC) tool to develop integrated strategies to improve air quality, human health and mitigate climate change. The framework estimates emissions of greenhouse gases, SLCPs and air pollutants for historical years, and future projections for baseline and mitigation scenarios. These emissions are then used to quantify i) population-weighted annual average ambient PM2.5 concentrations across the target country, ii) household PM2.5 exposure of different population groups living in households cooking using different fuels/technologies and iii) radiative forcing from all emissions. Health impacts (premature mortality) attributable to ambient and household PM2.5 exposure and changes in global average temperature change are then estimated. This framework is applied in Bangladesh to evaluate the air quality and climate change benefits from implementation of Bangladesh's Nationally Determined Contribution (NDC) and National Action Plan to reduce SLCPs. Results show that the measures included to reduce GHGs in Bangladesh's NDC also have substantial benefits for air quality and human health. Full implementation of Bangladesh's NDC, and National SLCP Plan would reduce carbon dioxide, methane, black carbon and primary PM2.5 emissions by 25%, 34%, 46% and 45%, respectively in 2030 compared to a baseline scenario. These emission reductions could reduce population-weighted ambient PM2.5 concentrations in Bangladesh by 18% in 2030, and avoid approximately 12,000 and 100,000 premature deaths attributable to ambient and household PM2.5 exposures, respectively, in 2030. As countries are simultaneously planning to achieve the climate goals in the Paris Agreement, improve air quality to reduce health impacts and achieve the Sustainable Development Goals, the LEAP-IBC tool provides a practical framework by which planners can develop integrated strategies, achieving multiple air quality and climate benefits.

Controls on accumulation and soil solution partitioning of heavy metals across upland sites in United Kingdom (UK).

A significant body of knowledge suggests that soil solution pH and dissolved organic carbon (DOC) strongly influence metal concentrations and speciation in porewater, however, these effects vary between different metals. This study investigated the factors influencing soil and soil solution concentrations of copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) under field conditions in upland soils from UK having a wide range of pH, DOC and organic matter contents. The study primarily focussed on predicting soil and soil solution metal concentrations from the data on total soil metal concentrations (HNO3 extracts) and soil and soil solution properties (pH, DOC and organic matter content). We tested the multiple regression models proposed by Tipping et al. (2003) to predict heavy metal concentrations in soil solutions and the results indicated a better fit (higher R2 values) in both studies for Pb compared to the Zn and Cu concentrations. Both studies observed consistent negative relationships of metals with pH and loss on ignition (LOI) suggesting an increase in soil solution metal concentrations with increasing acidity. The positive relationship between Pb concentrations in porewater and HNO3 extracts was similar for both studies, however, similar relationships were not found for the Zn and Cu concentrations because of the negative coefficients for these metals in our study. The results of this study conclude that the predictive equations of Tipping et al. (2003) may not be applicable to the field sites where the range of DOC and metal concentrations is much lower than their study. Our study also suggests that the extent to which metals are partitioned into soil solution is lower in soils with a higher organic matter contents due to binding of these metals to soil organic matter.

Updated Global Estimates of Respiratory Mortality in Adults ≥30Years of Age Attributable to Long-Term Ozone Exposure.

BACKGROUND: Relative risk estimates for long-term ozone (O3) exposure and respiratory mortality from the American Cancer Society Cancer Prevention Study II (ACS CPS-II) cohort have been used to estimate global O3-attributable mortality in adults. Updated relative risk estimates are now available for the same cohort based on an expanded study population with longer follow-up. OBJECTIVES: We estimated the global burden and spatial distribution of respiratory mortality attributable to long-term O3 exposure in adults ≥30y of age using updated effect estimates from the ACS CPS-II cohort. METHODS: We used GEOS-Chem simulations (2×2.5º grid resolution) to estimate annual O3 exposures, and estimated total respiratory deaths in 2010 that were attributable to long-term annual O3 exposure based on the updated relative risk estimates and minimum risk thresholds set at the minimum or fifth percentile of O3 exposure in the most recent CPS-II analysis. These estimates were compared with attributable mortality based on the earlier CPS-II analysis, using 6-mo average exposures and risk thresholds corresponding to the minimum or fifth percentile of O3 exposure in the earlier study population. RESULTS: We estimated 1.04-1.23 million respiratory deaths in adults attributable to O3 exposures using the updated relative risk estimate and exposure parameters, compared with 0.40-0.55 million respiratory deaths attributable to O3 exposures based on the earlier CPS-II risk estimate and parameters. Increases in estimated attributable mortality were larger in northern India, southeast China, and Pakistan than in Europe, eastern United States, and northeast China. CONCLUSIONS: These findings suggest that the potential magnitude of health benefits of air quality policies targeting O3, health co-benefits of climate mitigation policies, and health implications of climate change-driven changes in O3 concentrations, are larger than previously thought. https://doi.org/10.1289/EHP1390.

Preterm birth associated with maternal fine particulate matter exposure: A global, regional and national assessment.

Reduction of preterm births (<37 completed weeks of gestation) would substantially reduce neonatal and infant mortality, and deleterious health effects in survivors. Maternal fine particulate matter (PM2.5) exposure has been identified as a possible risk factor contributing to preterm birth. The aim of this study was to produce the first estimates of ambient PM2.5-associated preterm births for 183 individual countries and globally. To do this, national, population-weighted, annual average ambient PM2.5 concentration, preterm birth rate and number of livebirths were combined to calculate the number of PM2.5-associated preterm births in 2010 for 183 countries. Uncertainty was quantified using Monte-Carlo simulations, and analyses were undertaken to investigate the sensitivity of PM2.5-associated preterm birth estimates to assumptions about the shape of the concentration-response function at low and high PM2.5 exposures, inclusion of provider-initiated preterm births, and exposure to indoor air pollution. Globally, in 2010, the number of PM2.5-associated preterm births was estimated as 2.7 million (1.8-3.5 million, 18% (12-24%) of total preterm births globally) with a low concentration cut-off (LCC) set at 10µgm-3, and 3.4 million (2.4-4.2 million, 23% (16-28%)) with a LCC of 4.3µgm-3. South and East Asia, North Africa/Middle East and West sub-Saharan Africa had the largest contribution to the global total, and the largest percentage of preterm births associated with PM2.5. Sensitivity analyses showed that PM2.5-associated preterm birth estimates were 24% lower when provider-initiated preterm births were excluded, 38-51% lower when risk was confined to the PM2.5 exposure range in the studies used to derive the effect estimate, and 56% lower when mothers who live in households that cook with solid fuels (and whose personal PM2.5 exposure is likely dominated by indoor air pollution) were excluded. The concentration-response function applied here derives from a meta-analysis of studies, most of which were conducted in the US and Europe, and its application to the areas of the world where we estimate the greatest effects on preterm births remains uncertain. Nevertheless, the substantial percentage of preterm births estimated to be associated with anthropogenic PM2.5 (18% (13%-24%) of total preterm births globally) indicates that reduction of maternal PM2.5 exposure through emission reduction strategies should be considered alongside mitigation of other risk factors associated with preterm births.

How does elevated ozone reduce methane emissions from peatlands?

The effects of increased tropospheric ozone (O3) pollution levels on methane (CH4) emissions from peatlands, and their underlying mechanisms, remain unclear. In this study, we exposed peatland mesocosms from a temperate wet heath dominated by the sedge Schoenus nigricans and Sphagnum papillosum to four O3 treatments in open-top chambers for 2.5years, to investigate the O3 impacts on CH4 emissions and the processes that underpin these responses. Summer CH4 emissions, were significantly reduced, by 27% over the experiment, due to summer daytime (8hday-1) O3 exposure to non-filtered air (NFA) plus 35ppb O3, but were not significantly affected by year-round, 24hday-1, exposure to NFA plus 10ppb or NFA plus 25ppb O3. There was no evidence that the reduced CH4 emissions in response to elevated summer O3 exposure were caused by reduced plant-derived carbon availability below-ground, because we found no significant effect of high summer O3 exposure on root biomass, pore water dissolved organic carbon concentrations or the contribution of recent photosynthate to CH4 emissions. Our CH4 production potential and CH4 oxidation potential measurements in the different O3 treatments could also not explain the observed CH4 emission responses to O3. However, pore water ammonium concentrations at 20cm depth were consistently reduced during the experiment by elevated summer O3 exposure, and strong positive correlations were observed between CH4 emission and pore water ammonium concentration at three peat depths over the 2.5-year study. Our results therefore imply that elevated regional O3 exposures in summer, but not the small increases in northern hemisphere annual mean background O3 concentrations predicted over this century, may lead to reduced CH4 emissions from temperate peatlands as a consequence of reductions in soil inorganic nitrogen affecting methanogenic and/or methanotrophic activity.

Current and future ozone risks to global terrestrial biodiversity and ecosystem processes.

Risks associated with exposure of individual plant species to ozone (O3) are well documented, but implications for terrestrial biodiversity and ecosystem processes have received insufficient attention. This is an important gap because feedbacks to the atmosphere may change as future O3 levels increase or decrease, depending on air quality and climate policies. Global simulation of O3 using the Community Earth System Model (CESM) revealed that in 2000, about 40% of the Global 200 terrestrial ecoregions (ER) were exposed to O3 above thresholds for ecological risks, with highest exposures in North America and Southern Europe, where there is field evidence of adverse effects of O3, and in central Asia. Experimental studies show that O3 can adversely affect the growth and flowering of plants and alter species composition and richness, although some communities can be resilient. Additional effects include changes in water flux regulation, pollination efficiency, and plant pathogen development. Recent research is unraveling a range of effects belowground, including changes in soil invertebrates, plant litter quantity and quality, decomposition, and nutrient cycling and carbon pools. Changes are likely slow and may take decades to become detectable. CESM simulations for 2050 show that O3 exposure under emission scenario RCP8.5 increases in all major biomes and that policies represented in scenario RCP4.5 do not lead to a general reduction in O3 risks; rather, 50% of ERs still show an increase in exposure. Although a conceptual model is lacking to extrapolate documented effects to ERs with limited or no local information, and there is uncertainty about interactions with nitrogen input and climate change, the analysis suggests that in many ERs, O3 risks will persist for biodiversity at different trophic levels, and for a range of ecosystem processes and feedbacks, which deserves more attention when assessing ecological implications of future atmospheric pollution and climate change.

Using Qualitative and Quantitative Methods to Choose a Habitat Quality Metric for Air Pollution Policy Evaluation.

Atmospheric nitrogen (N) deposition has had detrimental effects on species composition in a range of sensitive habitats, although N deposition can also increase agricultural productivity and carbon storage, and favours a few species considered of importance for conservation. Conservation targets are multiple, and increasingly incorporate services derived from nature as well as concepts of intrinsic value. Priorities vary. How then should changes in a set of species caused by drivers such as N deposition be assessed? We used a novel combination of qualitative semi-structured interviews and quantitative ranking to elucidate the views of conservation professionals specialising in grasslands, heathlands and mires. Although conservation management goals are varied, terrestrial habitat quality is mainly assessed by these specialists on the basis of plant species, since these are readily observed. The presence and abundance of plant species that are scarce, or have important functional roles, emerged as important criteria for judging overall habitat quality. However, species defined as 'positive indicator-species' (not particularly scarce, but distinctive for the habitat) were considered particularly important. Scarce species are by definition not always found, and the presence of functionally important species is not a sufficient indicator of site quality. Habitat quality as assessed by the key informants was rank-correlated with the number of positive indicator-species present at a site for seven of the nine habitat classes assessed. Other metrics such as species-richness or a metric of scarcity were inconsistently or not correlated with the specialists' assessments. We recommend that metrics of habitat quality used to assess N pollution impacts are based on the occurrence of, or habitat-suitability for, distinctive species. Metrics of this type are likely to be widely applicable for assessing habitat change in response to different drivers. The novel combined qualitative and quantitative approach taken to elucidate the priorities of conservation professionals could be usefully applied in other contexts.

A pharmacoeconomic approach to assessing the costs and benefits of air quality interventions that improve health: a case study.

OBJECTIVE: This paper explores the use of pharmacoeconomic methods of valuation to health impacts resulting from exposure to poor air quality. In using such methods, interventions that reduce exposure to poor air quality can be directly compared, in terms of value for money (or cost-effectiveness), with competing demands for finite resources, including other public health interventions. DESIGN: Using results estimated as part of a health impact assessment regarding a West Yorkshire Low Emission Zone strategy, this paper quantifies cost-saving and health-improving implications of transport policy through its impact on air quality. DATA SOURCE: Estimates of health-related quality of life and the National Health Service (NHS)/Personal Social Services (PSS) costs for identified health events were based on data from Leeds and Bradford using peer-reviewed publications or Office for National Statistics releases. POPULATION: Inhabitants of the area within the outer ring roads of Leeds and Bradford. MAIN OUTCOMES MEASURES: NHS and PSS costs and quality-adjusted life years (QALYs). RESULTS: Averting an all-cause mortality death generates 8.4 QALYs. Each coronary event avoided saves £28 000 in NHS/PSS costs and generates 1.1 QALYs. For every fewer case of childhood asthma, there will be NHS/PSS cost saving of £3000 and a health benefit of 0.9 QALYs. A single term, low birthweight birth avoided saves £2000 in NHS/PSS costs. Preventing a preterm birth saves £24 000 in NHS/PSS costs and generates 1.3 QALYs. A scenario modelled in the West Yorkshire Low Emission Zone Feasibility Study, where pre-EURO 4 buses and HGVs are upgraded to EURO 6 by 2016 generates an annual benefit of £2.08 million and a one-off benefit of £3.3 million compared with a net present value cost of implementation of £6.3 million. CONCLUSIONS: Interventions to improve air quality and health should be evaluated and where improvement of population health is the primary objective, cost-effectiveness analysis using a NHS/PSS costs and QALYs framework is an appropriate methodology.

Citizen science identifies the effects of nitrogen dioxide and other environmental drivers on tar spot of sycamore.

Elevated sulphur dioxide (SO2) concentrations were the major cause of the absence of symptoms of tar spot (Rhytisma acerinum) of sycamore (Acer pseudoplatanus), in urban areas in the 1970s. The subsequent large decline in SO2 concentrations has not always been accompanied by increased tar spot symptoms, for reasons that have remained unresolved. We used a large citizen science survey, providing over 1000 records across England, to test two competing hypotheses proposed in earlier studies. We were able to demonstrate the validity of both hypotheses; tar spot symptoms were reduced where there were fewer fallen leaves as a source of inoculum, and elevated nitrogen dioxide concentrations reduced tar spot symptoms above a threshold concentration of about 20 µg m(-3). Symptom severity was also lower at sites with higher temperature and lower rainfall. Our findings demonstrate the power of citizen science to resolve competing hypotheses about the impacts of air pollution and other environmental drivers.

Consistent ozone-induced decreases in pasture forage quality across several grassland types and consequences for UK lamb production.

In this study we have demonstrated that rising background ozone has the potential to reduce grassland forage quality and explored the implications for livestock production. We analysed pasture samples from seven ozone exposure experiments comprising mesotrophic, calcareous, haymeadow and sanddune unimproved grasslands conducted in open-top chambers, solardomes and a field release system. Across all grassland types, there were significant increases in acid detergent fibre, crude fibre and lignin content with increasing ozone concentration, resulting in decreased pasture quality in terms of the metabolisable energy content of the vegetation. We derived a dose-response function for metabolisable energy of the grassland with ozone concentration, applicable to a range of grassland types, and used this to predict effects on pasture quality of UK vegetation at 1 km resolution using modelled ozone data for 2007 and for predicted higher average ozone concentrations in 2020. This showed a potential total reduction in lamb production in the UK of approximately 4% in 2020 compared to 2007. The largest impacts were in geographical areas of modest ozone increases between the two years, but where large numbers of lambs were present. For an individual farmer working to a very small cost margin this could represent a large reduction in profit, both in regions where the impacts per lamb and those where the impacts per km(2) of grazing land are largest. In the short term farmers could adapt their lamb management in response to changed forage quality by additional supplementary feed of high metabolisable energy content. Nationally this increase in annual additional feed in 2020 compared to 2007 would be 2,166 tonnes (an increase of 0.7%). Of added concern are the longer-term consequences of continual deterioration of pasture quality and the implications for changes in farming practices to compensate for potential reductions in livestock production capacity.

Evidence for differential effects of reduced and oxidised nitrogen deposition on vegetation independent of nitrogen load.

Nitrogen (N) deposition impacts natural and semi-natural ecosystems globally. The responses of vegetation to N deposition may, however, differ strongly between habitats and may be mediated by the form of N. Although much attention has been focused on the impact of total N deposition, the effects of reduced and oxidised N, independent of the total N deposition, have received less attention. In this paper, we present new analyses of national monitoring data in the UK to provide an extensive evaluation of whether there are differences in the effects of reduced and oxidised N deposition across eight habitat types (acid, calcareous and mesotrophic grasslands, upland and lowland heaths, bogs and mires, base-rich mires, woodlands). We analysed data from 6860 plots in the British Countryside Survey 2007 for effects of total N deposition and N form on species richness, Ellenberg N values and grass:forb ratio. Our results provide clear evidence that N deposition affects species richness in all habitats except base-rich mires, after factoring out correlated explanatory variables (climate and sulphur deposition). In addition, the form of N in deposition appears important for the biodiversity of grasslands and woodlands but not mires and heaths. Ellenberg N increased more in relation to NHx deposition than NOy deposition in all but one habitat type. Relationships between species richness and N form were habitat-specific: acid and mesotrophic grasslands appear more sensitive to NHx deposition while calcareous grasslands and woodlands appeared more responsive to NOy deposition. These relationships are likely driven by the preferences of the component plant species for oxidised or reduced forms of N, rather than by soil acidification.

Exploring the Links between Post-Industrial Landscape History and Ecology through Participatory Methods.

There is increasing recognition of the importance for local biodiversity of post-mining sites, many of which lie near communities that have suffered significant social and economic deprivation as the result of mine closures. However, no studies to date have actively used the knowledge of local communities to relate the history and treatment of post-mining sites to their current ecological status. We report a study of two post-mining sites in the Yorkshire coalfield of the UK in which the local community were involved in developing site histories and assessing plant and invertebrate species composition. Site histories developed using participatory GIS revealed that the sites had a mixture of areas of spontaneous succession and technical reclamation, and identified that both planned management interventions and informal activities influenced habitat heterogeneity and ecological diversity. Two groups of informal activity were identified as being of particular importance. Firstly, there has been active protection by the community of flower-rich habitats of conservation value (e.g. calcareous grassland) and distinctive plant species (e.g. orchids) which has also provided important foraging resources for butterfly and bumblebee species. Secondly, disturbance by activities such as use of motorbikes, informal camping, and cutting of trees and shrubs for fuel, as well as planned management interventions such as spreading of brick rubble, has provided habitat for plant species of open waste ground and locally uncommon invertebrate species which require patches of bare ground. This study demonstrates the importance of informal, and often unrecorded, activities by the local community in providing diverse habitats and increased biodiversity within a post-mining site, and shows that active engagement with the local community and use of local knowledge can enhance ecological interpretation of such sites and provide a stronger basis for successful future management.

Crucial Role for Outdoor Chemistry in Ultrafine Particle Formation in Modern Office Buildings.

In the developed world, we spend most of our time indoors, where we receive the majority of our exposure to air pollution. This paper reports model simulations of PM2.5 and ozone concentrations in identical landscape offices in three European cities: Athens, Helsinki, and Milan. We compare concentrations during an intense heatwave in August 2003 with a meteorologically more typical August in 2009. During the heatwave, average indoor ozone concentrations during office hours were 44, 19, and 41 ppb in Athens, Helsinki, and Milan respectively, enhanced by 7, 4, and 17 ppb respectively relative to 2009. Total predicted PM2.5 concentrations were 13.5, 3.6, and 17.2 µg m(-3) in Athens, Helsinki, and Milan respectively, enhanced by 0.5, 0.4, and 6.7 µg m(-3) respectively relative to 2009: the three cities were affected to differing extents by the heatwave. A significant portion of the indoor PM2.5 derived from gas-phase chemistry outdoors, producing 2.5, 0.8, and 4.8 µg m(-3) of the total concentrations in Athens, Helsinki, and Milan, respectively. Despite filtering office inlet supplies to remove outdoor particles, gas-phase precursors for particles can still enter offices, where conditions are ripe for new particles to form, particularly where biogenic emissions are important outdoors. This result has important implications for indoor air quality, particularly given the current trend for green walls on buildings, which will provide a potential source of biogenic emissions near to air inlet systems.

Can citizen science produce good science? Testing the OPAL Air Survey methodology, using lichens as indicators of nitrogenous pollution.

Citizen science is having increasing influence on environmental monitoring as its advantages are becoming recognised. However methodologies are often simplified to make them accessible to citizen scientists. We tested whether a recent citizen science survey (the OPAL Air Survey) could detect trends in lichen community composition over transects away from roads. We hypothesised that the abundance of nitrophilic lichens would decrease with distance from the road, while that of nitrophobic lichens would increase. The hypothesised changes were detected along strong pollution gradients, but not where the road source was relatively weak, or background pollution relatively high. We conclude that the simplified OPAL methodology can detect large contrasts in nitrogenous pollution, but it may not be able to detect more subtle changes in pollution exposure. Similar studies are needed in conjunction with the ever-growing body of citizen science work to ensure that the limitations of these methods are fully understood.

Effects of ozone on crops in north-west Pakistan.

Although ozone is well-documented to reduce crop yields in the densely populated Indo-Gangetic Plain, there is little knowledge of its effects in other parts of south Asia. We surveyed crops close to the city of Peshawar, in north-west Pakistan, for visible injury, linking this to passive measurements of ozone concentrations. Foliar injury was found on potato, onion and cotton when mean monthly ozone concentrations exceeded 45 ppb. The symptoms on onion were reproduced in ozone fumigation experiments, which also showed that daytime ozone concentrations of 60 ppb significantly reduce the growth of a major Pakistani onion variety. Aphid infestation on spinach was also reduced at these elevated ozone concentrations. The ozone concentrations measured in April-May in Peshawar, and used in the fumigation experiment, are comparable to those that have been modelled to occur over many parts of south Asia, where ozone may be a significant threat to sensitive crops.

Dissolved organic carbon (DOC) concentrations in UK soils and the influence of soil, vegetation type and seasonality.

Given the lack of studies which measured dissolved organic carbon (DOC) over long periods, especially in non-forest habitat, the aim of this study was to expand the existing datasets with data of mainly non-forest sites that were representative of the major soil and habitat types in the UK. A further aim was to predict DOC concentrations from a number of biotic and abiotic explanatory variables such as rainfall, temperature, vegetation type and soil type in a multivariate way. Pore water was sampled using Rhizon or Prenart samplers at two to three week intervals for 1 year. DOC, pH, organic carbon, carbon/nitrogen (C:N) ratios of soils and slope were measured and data on vegetation, soil type, temperature and precipitation were obtained. The majority of the variation in DOC concentrations between the UK sites could be explained by simple empirical models that included annual precipitation, and soil C:N ratio with precipitation being negatively related to DOC concentrations and C:N ratio being positively related to DOC concentrations. Our study adds significantly to the data reporting DOC concentrations in soils, especially in grasslands, heathlands and moorlands. Broad climatic and site factors have been identified as key factors influencing DOC concentrations.

Hydrogen fluoride damage to vegetation from peri-urban brick kilns in Asia: a growing but unrecognised problem?

The rapid urbanisation of many cities in south and south-east Asia has increased the demand for bricks, which are typically supplied from brick kilns in peri-urban areas. We report visible foliar damage to mango, apricot and plum trees in the vicinity of traditional Bull's Trench brick kilns in Peshawar, Pakistan. Visible injury symptoms, hydrogen fluoride concentrations in air, and foliar fluoride concentrations were all greater in the vicinity of brick kilns than at more distant sites, indicating that fluoride emissions from brick kilns were the main cause of damage. Interviews with local farmers established the significant impact of this damage on their livelihoods. Since poorly regulated brick kilns are often found close to important peri-urban agricultural areas, we suggest that this may be a growing but unrecognised environmental problem in regions of Asia where emission control in brick kilns has not been improved.

Effects of ozone on species composition in an upland grassland.

Northern hemispheric background concentrations of ozone are increasing, but few studies have assessed the ecological significance of these changes for grasslands of high conservation value under field conditions. We carried out a 3-year field experiment in which ozone was released at a controlled rate over three experimental transects to produce concentration gradients over the field site, an upland mesotrophic grassland located in the UK. We measured individual species biomass in an annual hay cut in plots receiving ambient ozone, and ambient ozone elevated by mean concentrations of approximately 4 ppb and 10 ppb in the growing seasons of 2008 and 2009. There was a significant negative effect of ozone exposure on herb biomass, but not total grass or legume biomass, in 2008 and 2009. Within the herb fraction, ozone exposure significantly decreased the biomass of Ranunculus species and that of the hemi-parasitic species Rhinanthus minor. Multivariate analysis of species composition, taking into account spatial variation in soil conditions and ozone exposure, showed no significant ozone effect on the grass component. In contrast, by 2009, ozone had become the dominant factor influencing species composition within the combined herb and legume component. Our results suggest that elevated ozone concentrations may be a significant barrier to achieving increased species diversity in managed grasslands.