Imperial College London

Professor Nigel Bell

Faculty of Natural SciencesCentre for Environmental Policy

Emeritus Professor of Environmental Pollution
 
 
 
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Contact

 

+44 (0)20 7594 9288n.bell

 
 
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Location

 

16 Prince's GardensSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

27 results found

Davies L, Bell JN, Bone J, Head M, Hill L, Howard C, Hobbs SJ, Jones DT, Power SA, Rose N, Ryder C, Seed L, Stevens G, Toumi R, Voulvoulis N, White PCet al., 2011, Open Air Laboratories (OPAL): a community-driven research programme., Environmental Pollution, Vol: 159, Pages: 2203-2210

OPAL is an English national programme that takes scientists into the community to investigate environmental issues. Biological monitoring plays a pivotal role covering topics of: i) soil and earthworms; ii) air, lichens and tar spot on sycamore; iii) water and aquatic invertebrates; iv) biodiversity and hedgerows; v) climate, clouds and thermal comfort. Each survey has been developed by an inter-disciplinary team and tested by voluntary, statutory and community sectors. Data are submitted via the web and instantly mapped. Preliminary results are presented, together with a discussion on data quality and uncertainty. Communities also investigate local pollution issues, ranging from nitrogen deposition on heathlands to traffic emissions on roadside vegetation. Over 200,000 people have participated so far, including over 1000 schools and 1000 voluntary groups. Benefits include a substantial, growing database on biodiversity and habitat condition, much from previously unsampled sites particularly in urban areas, and a more engaged public.

Journal article

Bell JNB, Honour SL, Power SA, 2011, Effects of vehicle exhaust emissions on urban wild plant species, ENVIRONMENTAL POLLUTION, Vol: 159, Pages: 1984-1990, ISSN: 0269-7491

Journal article

Kaliakatsou E, Bell JNB, Thirtle C, Rose D, Power SAet al., 2010, The impact of tropospheric ozone pollution on trial plot winter wheat yields in Great Britain - An econometric approach, ENVIRONMENTAL POLLUTION, Vol: 158, Pages: 1948-1954, ISSN: 0269-7491

Journal article

Honour SL, Bell JNB, Ashenden TW, Cape JN, Power SAet al., 2009, Responses of herbaceous plants to urban air pollution: Effects on growth, phenology and leaf surface characteristics, ENVIRONMENTAL POLLUTION, Vol: 157, Pages: 1279-1286, ISSN: 0269-7491

Journal article

McKinlay R, Plant JA, Bell JNB, Voulvoulis Net al., 2008, Calculating human exposure to endocrine disrupting pesticides via agricultural and non-agricultural exposure routes, Science of the Total Environment, Vol: 398, Pages: 1-12, ISSN: 0048-9697

Endocrine Disrupting Chemicals (EDCs) are of increasing concern because of their potential impacts on the environment, wildlife and human health. Pesticides and some pesticide metabolites are an important group of EDC, and exposure to them is a poorly quantified source of human and environmental exposure to such chemicals generally. Models for estimating human exposure to Endocrine Disrupting (ED) pesticides are an important risk management tool. Probabilistic models are now being used in addition to deterministic ones in all areas of risk assessment. These can provide more realistic exposure estimates, because they are better able to deal with variation and uncertainty more effectively and better inform risk management decisions. Deterministic models are still used and are of great value where exposure data are scarce. Models or groups of models that provide holistic human ED pesticide exposure estimates are required if the risk posed to humans by ED pesticides is to be better assessed. Much more research is needed to quantify different exposure routes such as exposure from agricultural spray drift and the medical use of pesticides to develop such models. Most available probabilistic models of human exposure were developed in the USA and require modification for use elsewhere. In particular, datasets equivalent to those used to create and apply the American models are required. This paper examines the known routes of human pesticide exposure with particular reference to ED pesticides and their quantification as unlike pesticides generally, many ED pesticides are harmful at very low doses, especially if exposure occurs during sensitive stages of development, producing effects that may not manifest for many years or that affect descendants via epigenetic changes. It also summarises available deterministic and probabilistic models commonly used to calculate human exposure. The main requirement if such models are to be used in the UK is more quantitative data on the so

Journal article

McKinlay R, Plant JA, Bell JNB, Voulvoulis Net al., 2008, Endocrine disrupting pesticides: implications for risk assessment, Environment International, Vol: 34, Pages: 168-183, ISSN: 0160-4120

Endocrine disrupting (ED) chemicals are compounds that alter the normal functioning of the endocrine system, potentially causing disease or deformity in organisms and their offspring. Pesticides are used widely to kill unwanted organisms in crops, public areas, homes and gardens and medicinally to kill parasites. Many are proven or suspected to be EDs. Ancient physiological similarities between different vertebrate groups suggest that disorders observed in wildlife may indicate risks to humans. This makes accurate risk assessment and effective legislation difficult. In this paper, the hazardous properties of pesticides which are known to have ED properties are reviewed in order to assess the implications for risk assessment. As well as data on sources of exposure in the United Kingdom (UK) an assessment of the evidence on the health effects of ED pesticides is also included. In total, 127 have been identified from the literature and their effects and modes of action are listed in this paper. Using the UK as a case study, the types and quantities of pesticides used, and their methods of application are assessed, along with their potential pathways to humans. In the UK reliable data are available only for agricultural use, so non-agricultural routes of pesticide exposure have been poorly quantified. The exposure of people resident in or visiting rural areas could also have been grossly under-estimated. Material links between ED pesticide use and specific illnesses or deformities are complicated by the multifactorial nature of disease, which can be affected by factors such as diet. Despite these difficulties, a large body of evidence has accumulated linking specific conditions to ED pesticides in wildlife and humans. A more precautionary approach to the use of ED pesticides, especially for non-essential purposes is proposed. (C) 2007 Elsevier Ltd. All fights reserved.

Journal article

Jamieson KS, ApSimon HM, Jamieson SS, Bell JNB, Yost MGet al., 2007, The effects of electric fields on charged molecules and particles in individual microenvironments, Atmospheric Environment, Vol: 41, Pages: 5224-5236, ISSN: 1352-2310

Journal article

Larsen RS, Bell JNB, James PW, Chimonides PJ, Rumsey FJ, Tremper A, Purvis OWet al., 2007, Lichen and bryophyte distribution on oak in London in relation to air pollution and bark acidity, ENVIRONMENTAL POLLUTION, Vol: 146, Pages: 332-340, ISSN: 0269-7491

Journal article

Davies L, Bates JW, Bell JNB, James PW, Purvis OWet al., 2007, Diversity and sensitivity of epiphytes to oxides of nitrogen in London, ENVIRONMENTAL POLLUTION, Vol: 146, Pages: 299-310, ISSN: 0269-7491

Journal article

Bell JNB, Shaw G, 2005, Ecological lessons from the Chernobyl accident., Environ Int, Vol: 31, Pages: 771-777, ISSN: 0160-4120

The Chernobyl nuclear accident in 1986 not only caused serious ecological problems in both the Ukraine and Belarus, which continue to the present day, but also contaminated a large part of the higher latitudes of the northern hemisphere. In this paper an overview is given of the latter problems in upland UK, where ecological problems still remain some 17 years after initial contamination. Following deposition of radiocaesium and radioiodine in May 1986, measurements of radioactivity in grass and soil indicated a rapidly declining problem as the radioiodine decayed and the radiocaesium became immobilised by attachment to clay particles. However, these studies, as well as the advice received by the Ministry of Agriculture, Fisheries and Food, were based on lowland agricultural soils, with high clay and low organic matter contents. The behaviour of radiocaesium in upland UK turned out to be dominated by high and persistent levels of mobility and bioavailability. This resulted in the free passage of radiocaesium through the food chain and into sheep. Consequently the Ministry banned the sale and movement of sheep over large areas of upland Britain, with bans remaining on some farms to the present day. Present day predictions suggest that these bans will continue in some cases for some years to come. The causes of radiocaesium mobility in upland areas have subsequently been the subject of intense investigation centred around vegetation and, in particular, soil characteristics. Soil types were identified which were particularly vulnerable in this respect and, where these coincided with high levels of deposition, sheep bans tended to be imposed. While much of the earlier work suggested that a low clay content was the main reason for continuing mobility, a very high organic matter content is now also believed to play a major role, this being a characteristic of wet and acidic upland UK soils. The overall message from this affair is the importance of a fundamental understand

Journal article

Collins CD, Gravett AE, Bell JNB, 2004, The deposition and translocation of methyl iodide by crops, HEALTH PHYSICS, Vol: 87, Pages: 512-516, ISSN: 0017-9078

Journal article

Kim CG, Power SA, Bell JNB, 2004, Effects of host plant exposure to cadmium on mycorrhizal infection and soluble carbohydrate levels of <i>Pinus sylvestris</i> seedlings, ENVIRONMENTAL POLLUTION, Vol: 131, Pages: 287-294, ISSN: 0269-7491

Journal article

Shaw G, Wadey P, Bell JNB, 2004, Radionuclide transport above a near-surface water table: IV. Soil migration and crop uptake of chlorine-36 and technetium-99, 1990 to 1993., J Environ Qual, Vol: 33, Pages: 2272-2280, ISSN: 0047-2425

Vertical distributions of (36)Cl and (99)Tc are presented from deep and shallow lysimeters above artificially controlled water tables for a 4-yr experiment from 1990 to 1993. Activity concentration profiles were all measured in late summer when a winter wheat (Triticum aestivum L. cv. Pastiche) crop was harvested. After harvest, activity concentrations in different organs of the crop were determined and crop uptake quantified as both an inventory ratio (IR) and a transfer factor (TF(w)), weighted to account for differential root and radionuclide distributions within the soil profile. Vertical distributions of radionuclides, crop roots within the soil, and IR and TF(w) values were each subjected to analysis of variance to estimate the individual and combined effects of soil depth and the year of the experiment on the results obtained. Chlorine-36 and (99)Tc exhibited highly significant variations in activity concentrations with soil depth and from year to year, indicating considerable physical mobility of both radionuclides. Soil-to-plant transfer was also high for both radionuclides compared with data obtained for gamma-emitting radionuclides. The IR values indicated that up to 40% of (36)Cl was incorporated in the crop's tissues at harvest, compared with a maximum of less than 1% for the less mobile gamma-emitting radionuclides. On the basis of the TF(w) values determined, (36)Cl uptake by winter wheat exceeded (99)Tc uptake, indicating that (36)Cl is highly bioavailable. Factors controlling the migration and bioavailability of both (36)Cl and (99)Tc in soils are discussed.

Journal article

Kim CG, Power SA, Bell JNB, 2003, Effects of cadmium on growth and glucose utilisation of ectomycorrhizal fungi in vitro, MYCORRHIZA, Vol: 13, Pages: 223-226, ISSN: 0940-6360

Journal article

Bostock AC, Shaw G, Bell JNB, 2003, The volatilisation and sorption of (129)I in coniferous forest, grassland and frozen soils., J Environ Radioact, Vol: 70, Pages: 29-42, ISSN: 0265-931X

129I is a potentially important radionuclide in safety assessments of proposed deep geological radioactive waste repositories due to its radiotoxicity, high mobility and long physical half-life (15.7 million years). In soils, iodine is present both in an inorganic form and in organohalide complexes, some of which are volatile under natural environmental conditions. This study has examined volatilisation, sorption and the effect of freezing on sorption and loss of (125)I (physical half-life 60.2 days), as a surrogate for (129)I, within coniferous forest and grassland soils. The results do not suggest that volatilisation from these soils is a significant pathway for the transport of (129)I. Strong and specific sorption of iodine to humic substances has been demonstrated, which is reduced at freezing temperatures. It is hypothesised that rapid sorption to soil humic substances can significantly reduce volatilisation rates. The effect of freezing conditions on iodine extractability from soils suggests a microbially mediated sorption process.

Journal article

Power SA, Barker CG, Allchin EA, Ashmore MR, Bell JNet al., 2001, Habitat management: a tool to modify ecosystem impacts of nitrogen deposition?, ScientificWorldJournal, Vol: 1 Suppl 2, Pages: 714-721

Atmospheric nitrogen deposition has been shown to affect both the structure and the function of heathland ecosystems. Heathlands are semi-natural habitats and, as such, undergo regular management by mowing or burning. Different forms of management remove more or less nutrients from the system, so habitat management has the potential to mitigate some of the effects of atmospheric deposition. Data from a dynamic vegetation model and two field experiments are presented. The first involves nitrogen addition following different forms of habitat management. The second tests the use of habitat management to promote heathland recovery after a reduction in nitrogen deposition. Both modelling and experimental approaches suggest that plant and microbial response to nitrogen is affected by management. Shoot growth and rates of decomposition were lowest in plots managed using more intensive techniques, including mowing with litter removal and a high temperature burn. Field data also indicate that ecosystem recovery from prolonged elevated inputs of nitrogen may take many years, or even decades, even after the removal of plant and litter nitrogen stores which accompanies the more intensive forms of habitat management.

Journal article

Collins CD, Bell JNB, 2001, Experimental studies on the deposition to crops of radioactive gases released from gas-cooled reactors - III. Carbon-14 dioxide, JOURNAL OF ENVIRONMENTAL RADIOACTIVITY, Vol: 53, Pages: 215-229, ISSN: 0265-931X

Journal article

Collins CD, Bell JNB, Crews C, 2000, Benzene accumulation in horticultural crops, CHEMOSPHERE, Vol: 40, Pages: 109-114, ISSN: 0045-6535

Journal article

Kinnersley RP, Shaw G, Bell JN, Minski MJ, Goddard AJet al., 1996, Loss of particulate contaminants from plant canopies under wet and dry conditions., Environ Pollut, Vol: 91, Pages: 227-235, ISSN: 0269-7491

There is a requirement for data describing the loss with time of particulate contamination from plant canopies. Measurements were made of the loss rates of monodispersed silica spheres (three sizes, with Mass Median Aerodynamic Diameters (MMADs) 1.9, 5.3 and 8.4 microm) from wheat (Triticum aestivum) and broad bean (Vicia faba) canopies. The spheres were labelled with tracers detectable by Instrumental Neutron Activation Analysis (INAA). Canopies were contaminated under realistic turbulence conditions in a wind tunnel, then removed to sheltered and exposed field sites or to a glasshouse containing a rain simulator. Samples were taken periodically, and the level of contamination per plant determined by INAA. Statistical analysis of the resulting data suggested an offset exponential loss model, with a residue of deposit that is not lost over time. Loss half-lives in the order of 1-2 days were obtained for an exposed wheat crop and 3-4 days for a partially sheltered wheat crop, with permanent residues of initial deposit for the exposed crop of 4-8%, and for the partially sheltered crop of 22-52%. A broad bean crop under glasshouse conditions showed loss half-lives of 0.5-1.5 days with residues of 22-26% initial contamination. A double exponential loss model also fitted the data well in some cases, and it is possible that a slow loss of the residual deposit occurs, being masked by noise in the current data set.

Journal article

Brown SL, Bell JN, 1995, Earthworms and radionuclides, with experimental investigations on the uptake and exchangeability of radiocaesium., Environ Pollut, Vol: 88, Pages: 27-39, ISSN: 0269-7491

The potential influence of earthworm activity on the mobility of radionuclides in soils and their subsequent availability for uptake by plants and transfer to higher trophic levels is briefly reviewed. The accumulation of caesium by the earthworm Aporrectodea longa from soil and from plant litter was investigated in laboratory experiments, as was the effect of reworking (through burrowing and ingestion) soil and soil with added organic material, on the extractability of caesium (ammonium acetate extraction). Soil was spiked with (134)Cs, organic matter with (137)Cs. In soil-fed worms, most of the radioactivity measured was eliminated with the gut contents; 5-25% of the ingested radioactivity was retained or assimilated. Loss of caesium from soil-fed worms followed a two component curve, with an initial rapid loss due to gut clearance (half-life of loss (Tb1/2) of about 0.2-0.6 days) and a slower loss of assimilated caesium (Tb1/2 of 15-26 days). Loss rates of assimilated caesium from worms fed on fragmented apple leaves were found to have half-lives of 18-54 days. Assimilation of caesium from apple leaves was higher than from soil, ranging from 55-100% of the activity measured before gut clearance. Dry weight transfer factors (concentration in worm tissue/concentration in substrate) for worms cleared of their gut contents were similar for the two substrates 0.04 and 0.04 for two loss experiments with worms fed on radioactive soil, and 0.03 and 0.05 for worms fed on apple leaves. After three months of reworking soil and soil/organic mixtures, A. longa was found to have no measurable effect on the extractable fraction of caesium. If earthworms have any subtle effects they were masked by changes in availability that occurred when the spiked soil and organic substrates were mixed together. Only about half of the extractable fraction in soil was recovered when soil was mixed with organic material suggesting that some of the labile fraction in soil had become complexed wi

Journal article

WADEY P, SHAW G, BELL JN, MINSKI MJet al., 1994, RADIONUCLIDE TRANSPORT ABOVE A NEAR-SURFACE WATER-TABLE .2. VERTICAL-DISTRIBUTION OF GAMMA-ACTIVITIES WITHIN SOIL PROFILES IN RELATION TO WHEAT ROOTING DENSITY AND SOIL-TO-PLANT TRANSFERS, JOURNAL OF ENVIRONMENTAL QUALITY, Vol: 23, Pages: 1330-1337, ISSN: 0047-2425

Journal article

Taylor HJ, Bell JN, 1992, Tolerance to SO2, NO2 and their mixture in Plantago major L. populations., Environ Pollut, Vol: 76, Pages: 19-24, ISSN: 0269-7491

The possible evolution of tolerance to NO2, alone or in combination with SO2 was investigated in three populations of Plantago major L., originating from Hyde Park in central London (polluted site), Ascot (clean site) and The Netherlands. Screening for sensitivity to the pollutants was carried out by means of chronic fumigations with NO2 or NO2 plus SO2 and acute fumigations with SO2, NO2 or their mixture. The Hyde Park population showed smaller growth reductions induced by the pollutant mixture, than did the other populations. In contrast no differential response in terms of foliar injury was observed after an acute fumigation with SO2+ NO2, but the Hyde Park population was the most sensitive to NO2 alone. The results indicate that selection for tolerance to SO2 does not confer tolerance to NO2 alone or the pollutant mixture.

Journal article

Houlden G, McNeill S, Craske A, Bell JNet al., 1991, Air pollution and agricultural aphid pests. II chamber filtration experiments., Environ Pollut, Vol: 72, Pages: 45-55, ISSN: 0269-7491

The responses of four major aphid pest species feeding on three major crops were studied in a series of experimental chambers on the roof of Imperial College in South Kensington, London. The experimental chambers were continually circulated with air which had been subjected to a variety of filtration treatments. In the first series of experiments there were three chambers subject to ambient air, charcoal-filtered air, and charcoal plus 'Purafil'-filtered air; in the subsequent experiments there were four chambers, a charcoal plus 'Purafil' plus charcoal treatment being added. These treatments provided a range of concentrations and mixtures of the ambient gases present at the site. The growth rate of aphids was measured both during filtration and post-filtration, the plants being exposed from sowing for either 42 or 84 days. In all cases there were significant effects on aphid performance which seemed to be most strongly linked to absolute and relative NO concentrations. The pattern of responses by the aphids accorded extremely well with those observed in closed-chamber fumigation experiments with stimulation of performance in relatively polluted air in all cases except Acyrthosiphon pisum (Harris) feeding on Vicia faba L. where the opposite effect was recorded.

Journal article

Houlden G, McNeil S, Aminu-Kano M, Bell JNet al., 1990, Air pollution and agricultural aphid pests. I: Fumigation experiments with SO2 and NO2., Environ Pollut, Vol: 67, Pages: 305-314, ISSN: 0269-7491

A wide range of aphid/host-crop systems was surveyed by means of fumigation experiments in closed chambers for sensitivity to SO(2) and NO(2) at a concentration of 100 nl litre(-1). Aphid performance was measured by the mean relative growth rate (MRGR) of individual aphids. In all cases, except for Acrythosiphon pisum (Harris) on Vicia fabaL., there were increases in the MRGR of the aphids feeding on fumigated plants as compared to clean air controls, both during and post fumigation. The increases in MRGR ranged from 6 to 75%, with the majority falling between 25 and 40%. A. pisum on V. faba showed a consistent negative response, with decreases in MRGR between -9 and -12%. The changes in aohid MRGR were not due to direct effects, as no significant differences in MRGR were observed between fumigated and clean air chambers when aphids were fed on artificial diet sachets during fumigation.

Journal article

BATES JW, BELL JNB, FARMER AM, 1990, EPIPHYTE RECOLONIZATION OF OAKS ALONG A GRADIENT OF AIR-POLLUTION IN SOUTH-EAST ENGLAND, 1979-1990, ENVIRONMENTAL POLLUTION, Vol: 68, Pages: 81-99, ISSN: 0269-7491

Journal article

KRUSE M, APSIMON HM, BELL JNB, 1989, VALIDITY AND UNCERTAINTY IN THE CALCULATION OF AN EMISSION INVENTORY FOR AMMONIA ARISING FROM AGRICULTURE IN GREAT-BRITAIN, ENVIRONMENTAL POLLUTION, Vol: 56, Pages: 237-257, ISSN: 0269-7491

Journal article

Ashmore MR, Bell JN, Mimmack A, 1988, Crop growth along a gradient of ambient air pollution., Environ Pollut, Vol: 53, Pages: 99-121, ISSN: 0269-7491

An experiment, designed to elucidate the relative importance of SO2, NO2, O3, and other environmental factors in influencing the performance of four cultivars of Trifolium pratense L. and Hordeum vulgare L., was performed by growing plants in situ along a transect from central London into the surrounding countryside. A multiple regression analysis provided evidence of significant effects of SO2, NO2, and, to a lesser extent, O3, on vegetative and reproductive growth parameters, although these differed according to pollutant, cultivar, species, and the parameter concerned. The significance of these findings for the impact of ambient air pollution on the growth of crops in the more polluted rural areas of western Europe is suggested by the fact that mean SO2, NO2, and O3 concentrations in the experimental area are less than 0.020 (39.2 microg/m3), 0.025 (47.75 microg/m3), and 0.030 ppm (58.8 microg/m3), respectively. The value of the technique is discussed with respect to other studies on the effects of low levels of air pollution on crops.

Journal article

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