Robert Storeton-West
University of Manchester
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Featured researches published by Robert Storeton-West.
Global Biogeochemical Cycles | 2004
Michael F. Billett; S. M. Palmer; D. Hope; C. Deacon; Robert Storeton-West; K.J. Hargreaves; Christophe Flechard; D. Fowler
Any change in the ability of northern peatlands to act as a sink for atmospheric CO2 will play a crucial part in the response of the Earth system to global warming. We argue that a true assessment of the sink-source relationships of peatland ecosystems requires that losses of C in drainage waters be included when determining annual net C uptake, thus connecting measurements of stream C fluxes with those made at the land surface-atmosphere interface. This was done by combining estimates of net ecosystem exchange (NEE) with stream water measurements of TOC, DIC, and gaseous C loss, in a 335-ha lowland temperate peatland catchment (55°48.80′N, 03°14.40′W) in central Scotland over a 2-year period (1996–1998). Mean annual downstream C flux was 304 (±62) kg C ha−1 yr−1, of which total organic carbon (TOC) contributed 93%, the remainder being dissolved inorganic carbon (DIC) and free CO2. At the catchment outlet evasion loss of CO2 from the stream surface was estimated to be an additional 46 kg C ha−1 yr−1. Over the study period, NEE of CO2-C resulted in a flux from the atmosphere to the land surface of 278 (±25) kg C ha−1 yr−1. Net C loss in drainage water, including both the downstream flux and CO2 evasion from the stream surface to the atmosphere, was therefore greater or equal to the net annual C uptake as a result of photosynthesis/respiration at the land surface. By combining these and other flux terms, the overall C mass balance suggests that this system was either acting as a terrestrial C source or was C neutral.
Water Air and Soil Pollution | 2001
D. Fowler; Chris Flechard; J. Neil Cape; Robert Storeton-West; Mhairi Coyle
Ozone deposition to vegetation represents the major sink for boundary layer ozone and yet the underlying mechanism of reaction and uptake at the surface is poorly understood. While overall rates of O3 deposition are known, the fractions of the flux absorbed by stomata and deposited to non-stomatal surfaces in the field have been poorly quantified. This paper reports 4 years of continuous fluxes by micrometeorological methods to moorland vegetation in southern Scotland. The flux has been partitioned between stomatal and non-stomatal fluxes and shows over a seasonal scale that the non-stomatal deposition (50 kg O3 ha− y−1) dominates the overall flux (77 kg O3 ha−1 y−1) and represents 70% of the total deposition. The surface resistance for non-stomatal O3 deposition (rns) decreases with temperature from 400 s m−1 at 0°C to 200 s m−1 at 15°C in dry conditions and is consistent with thermal decomposition of ozone at the surface with an apparent activation energy of about 36 kJ mole−1. The 4 years of continuous flux measurements show that stomatal conductance, when O3 concentrations are 80 µg m−3, is substantially smaller than for smaller O3 concentrations, although whether this is a response to VPD or O3 remains unclear.
Atmospheric Environment | 1997
Jens Lüttke; Volker Scheer; Karsten Levsen; G. Wünsch; J. Neil Cape; K.J. Hargreaves; Robert Storeton-West; K. Acker; W. Wieprecht; B.M.R. Jones
In this study, the concentrations of phenol, four nitrated phenols, their precursors and reactants in air and cloud water, are presented. The concentrations in air and cloud water were measured simultaneously at the summit of Great Dun Fell (GDF). The measured concentrations were compared with emission data, leading to the conclusion, that in particular dinitrophenols are formed by atmospheric reactions, while car exhaust accounts to a significant extent for the mononitrophenols observed. The experimental results point to a formation of dinitrophenols in the liquid phase (cloud droplets). This is corroborated by flow tube experiments which show that phenol in aqueous solution reacts with N2O5 and ClNO2 to form nitrophenols.
Atmospheric Environment | 1997
T. W. Choularton; R.N. Colvile; Keith N. Bower; Martin Gallagher; M. Wells; K.M. Beswick; B. G. Arends; J. J. Möls; G. P. A. Kos; S. Fuzzi; J. A. Lind; G. Orsi; M. C. Facchini; P. Laj; R. Gieray; P. Wieser; T. Engelhardt; A. Berner; C. Kruisz; Detlev Möller; K. Acker; W. Wieprecht; Jens Lüttke; K. Levsen; M. Bizjak; Hans-Christen Hansson; Sven Inge Cederfelt; Göran Frank; Besim Mentes; Bengt G. Martinsson
The 1993 Ground-based Cloud Experiment on Great Dun Fell used a wide range of measurements of trace gases, aerosol particles and cloud droplets at five sites to study their sources and sinks especially those in cloud. These measurements have been interpreted using a variety of models. The conclusions add to our knowledge of air pollution, acidification of the atmosphere and the ground, eutrophication and climate change. The experiment is designed to use the hill cap cloud as a flow-through reactor, and was conducted in varying levels of pollution typical of much of the rural temperate continental northern hemisphere in spring-time.
Environmental Pollution | 1992
K.J. Hargreaves; D. Fowler; Robert Storeton-West; Jan Duyzer
Fluxes of NO, NO2 and O3 were determined over a drained marshland pasture in south-east England by using flux-gradient techniques. Nitric oxide was found to be emitted at rates of up to 40 ng m(-2) s(-1), the rate of emission being related to the magnitude of the eddy diffusivity. Nitrogen dioxide deposited at rates of up to 90 ng m(-2) s(-1) under the control of stomatal resistance, a clear diurnal cycle being observed. Minimum canopy resistance was of the order of 80 s m(-1). Ozone deposition was also controlled by stomatal resistance, the minimum canopy resistance being around 100 s m(-1) and fluxes reaching a maximum of 220 ng m(-2) s(-1). Corrections made to NO and NO2 fluxes to compensate for chemical reactions showed flux divergences of the order of 30% for NO and NO2, but these were not statistically significantly different from the measured fluxes. The pasture was found to be a net sink for nitrogen in the form of NOx.
Plant and Soil | 2001
D. Fowler; Mhairi Coyle; Chris Flechard; K.J. Hargreaves; E. Nemitz; Robert Storeton-West; Mark A. Sutton; J.W. Erisman
The application of micrometeorology for flux measurements of nitrogen species between terrestrial ecosystems and the atmosphere and some of their main limitations are reviewed. New methods which are gaining rapid acceptance such as relaxed eddy accumulation are also described. A new development to provide long term average fluxes by time averaged gradients is shown to yield long-term average NH3 fluxes over moorland within 10% of values obtained using continuous wet denuder methods and at less than 10% of the cost. The use of mass balance methods to quantify fluxes at the plot, landscape and regional scale are described, and show that in suitable conditions and for some countries, methods to check national inventories of radiatively active gases are now available.
Atmospheric Environment | 1997
P. Laj; S. Fuzzi; M. C. Facchini; J. A. Lind; G. Orsi; M. Preiss; R. Maser; W. Jaeschke; E. Seyffer; K. Acker; W. Wieprecht; Detlev Möller; B. G. Arends; J. J. Möls; R.N. Colvile; Martin Gallagher; K.M. Beswick; K.J. Hargreaves; Robert Storeton-West; Mark A. Sutton
Abstract Experimental data from the Great Dun Fell Cloud Experiment 1993 were used to investigate interactions between soluble gases and cloud droplets. Concentrations of H 2 O 2 , SO 2 , CH 3 COOOH, HCOOH, and HCHO were monitored at different sites within and downwind of a hill cap cloud and their temporal and spatial evolution during several cloud events was investigated. Significant differences were found between in-cloud and out-of-cloud concentrations, most of which could not be explained by simple dissolution into cloud droplets. Concentration patterns were analysed in relation to the chemistry of cloud droplets and the gas/liquid equilibrium. Soluble gases do not undergo similar behaviour: CH 3 COOH simply dissolves in the aqueous phase and is outgassed upon cloud dissipation; instead, SO 2 is consumed by its reaction with H 2 O 2 . The behaviour of HCOOH is more complex because there is evidence for in-cloud chemical production. The formation of HCOOH interferes with the odd hydrogen cycle by enhancing the liquid-phase production of H 2 O 2 . The H 2 O 2 concentration in cloud therefore results from the balance of consumption by oxidation of SO 2 in-cloud production, and the rate by which it is supplied to the system by entrainment of new air into the clouds.
Atmospheric Environment | 1997
Keith N. Bower; T. W. Choularton; Martin Gallagher; R.N. Colvile; M. Wells; K.M. Beswick; Alfred Wiedensohler; Hans-Christen Hansson; Birgitta Svenningsson; Erik Swietlicki; Manfred Wendisch; A. Berner; C. Kruisz; P. Laj; M. C. Facchini; S. Fuzzi; M. Bizjak; G. J. Dollard; B.M.R. Jones; K. Acker; W. Wieprecht; M. Preiss; Mark A. Sutton; K.J. Hargreaves; Robert Storeton-West; J.N. Cape; B. G. Arends
Abstract Observations are presented of the aerosol size distribution both upwind and downwind of the Great Dun Fell cap cloud. Simultaneous measurements of the cloud microphysics and cloud chemistry, and of the chemical composition of the aerosol both upwind and downwind of the hill were made along with measurements of sulphur dioxide, hydrogen peroxide and ozone. These observations are used for initialisation of, and for comparison with the predictions of a model of the air flow, cloud microphysics and cloud chemistry of the system. A broad droplet size distribution is often observed near to the hill summit, seemingly produced as a result of a complex supersaturation profile and by mixing between parcels with different ascent trajectories. The model generates several supersaturation peaks as the airstream ascends over the complex terrain, activating increasing numbers of droplets. In conditions where sulphate production in-cloud (due to the oxidation of S(IV) by hydrogen peroxide and ozone) is observed, there is a marked effect on the chemical evolution of the aerosol particles on which the droplets form. When sulphate production occurs, a significant modification of the aerosol size distribution and hygroscopic properties is both predicted and observed. The addition of sulphate mass to those aerosol particles nucleation scavenged by the cloud generally increases the ease with which they are subsequently able to act as cloud condensation nuclei (CCN). Often, this will lead to an increase in the number of CCN available for subsequent cloud formation, although this latter effect is shown to be strongly dependent upon the activation history of the droplets and the concentration of pollutant gases present in the interstitial air. Situations are also identified where cloud processing could lead to a reduction in the capacity of smaller aerosol to act as CCN.
Atmospheric Environment | 1997
R.N. Colvile; Keith N. Bower; T. W. Choularton; Martin Gallagher; K.M. Beswick; B. G. Arends; G. P. A. Kos; Wolfram Wobrock; D. Schell; K.J. Hargreaves; Robert Storeton-West; J.N. Cape; B.M.R. Jones; Alfred Wiedensohler; Hans-Christen Hansson; Manfred Wendisch; K. Acker; W. Wieprecht; S. Pahl; P. Winkler; A. Berner; C. Kruisz; R. Gieray
Synoptic and local meteorological conditions during the Spring 1993 Ground-based Cloud Experiment on Great Dun Fell are described, including cloud microphysics, general pollution levels and sources of air, especially for five case studies selected for detailed analysis. Periods when air was flowing across the hill are identified and the extent to which air mixed into the cloud from above reached the ground is estimated. To aid the interpretation of cloud chemistry and microphysics measurements, the horizontal and vertical extent of the cloud are used to estimate droplet lifetimes and to comment on the influence of complex terrain on peak supersaturation.
Atmospheric Environment | 1997
M. Wells; Keith N. Bower; T. W. Choularton; J.N. Cape; Mark A. Sutton; Robert Storeton-West; D. Fowler; Alfred Wiedensohler; Hans-Christen Hansson; Birgitta Svenningsson; Erik Swietlicki; Manfred Wendisch; B.M.R. Jones; G. J. Dollard; K. Acker; W. Wieprecht; M. Preiss; B. G. Arends; S. Pahl; Ax. Berner; C Kruisz; P Laj; M C Facchini; S. Fuzzi
Field data collected during the GDF 93 project indicated that during polluted conditions (SO2(g) > 2 ppbv, NH3(g) > 0.5 ppbv), sulphate and ammonium concentrations in air increased through cloud chemistry by as much as 25%. Similarly, ammonia was seen to be consumed by cloud processing and decreased by up to 20%. In comparatively clean conditions (SO2(g) < 0.5 ppbv, NH3(g) < 0.5 ppbv), the sulphate loading of the aerosol was seen to remain constant, and ammonium was lost from the aerosol and outgassed as ammonia, increasing ambient ammonia concentrations by as much as 0.5 ppbv. An ideal cloud chemistry model predicted up to 20% more sulphate production than is implied by the bulk aerosol data set. A non-ideal cloud chemistry model was used to estimate the final ammonium loading of the aerosol, which is determined by the transformation from wet cloud droplet to dry aerosol particles below their deliquescence point. The non-ideal model showed that in three of the four cases ammonia outgassed from evaporating cloud droplets, consistent with field observations, but at variance with the ideal chemistry model. The results indicate that in low pollution conditions clouds act to re-equilibrate reduced nitrogen in the aerosol phase with gaseous ammonia. The outgassed ammonia will then be rapidly deposited to semi-natural ecosystems downwind of such clouds.