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Papers by Mark Cave

Research paper thumbnail of Characterization of oral bioaccessibility of Potentially Toxic Elements (PTEs) in urban area of Belfast

Research paper thumbnail of ORAL BIOACCESSIBILITY OF POTENTIALLY TOXIC ELEMENTS (PTEs) IN URBAN AREA OF BELFAST

A literature survey has shown that no study has investigated the oral bioaccessibility of PTEs in... more A literature survey has shown that no study has investigated the oral bioaccessibility of PTEs in Nigeria dusts. Studies on human health risk of PTEs from urban Nigeria dust have been based only on total elemental concentrations. Whilst this protocol is useful in assessing human health of PTEs, it could lead to an over estimation of the risk considering the elemental sequestration in the dust samples. This study deviated from previous studies by examining the total concentrations as well as the oral bioaccessibility of 8 PTEs in 15 urban dust samples collected from Abakaliki, Ebonyi State, Nigeria. The result showed that high concentrations of Pb (ranging from 236-1815 mg/kg) were observed in 5 locations. The Unified Bioaccessibility Method (UBM) was used to investigate the oral bioaccessibility of these PTEs in the urban dust samples. The result revealed that all the PTEs were more bioaccessible in the gastric phase that the gastric + intestinal phase. The lead tolerable daily intake (TDI), as well as the bioaccessible TDI, was computed and results compared with a guideline value. © JASEM

Research paper thumbnail of Soil mineralogy and its effect on oral bioaccessibility of Ni and Cr in soils overlying basalt lavas, Northern Ireland

Research paper thumbnail of Stream sediment background concentrations in mineralised catchments in Northern Ireland: assessment of ‘pressures’ on water bodies in fulfilment of Water Framework Directive objectives

An approach for deriving sediment background metal and metalloid element concentrations using sys... more An approach for deriving sediment background metal and metalloid element concentrations using systematically collected geochemical survey data is demonstrated in the mineralised area associated with the Ordovician-Silurian rocks in counties Down and Armagh in Northern Ireland. Operationally-defined background ranges can be used for improving the assessment of the environmental pressures posed by historical mining on impacted catchments and establishing feasible catchment restoration goals. Deriving pre-mining baselines provides essential information for any proposed mineral development project, with direct benefit to the mineral sector and industry.

Research paper thumbnail of Technical Guidance Sheet (TGS) on normal levels of contaminants in English soils : cadmium (Cd) : technical guidance sheet TGS06, July 2012

Research paper thumbnail of Mercury, n-alkane and unresolved complex mixture hydrocarbon pollution in surface sediment across the rural–urban–estuarine continuum of the River Clyde, Scotland, UK

Earth and Environmental Science Transactions of The Royal Society of Edinburgh, Jun 1, 2017

ABSTRACTSurface sediments (n=85) from a 160-km river-estuarine transect of the Clyde, UK, were an... more ABSTRACTSurface sediments (n=85) from a 160-km river-estuarine transect of the Clyde, UK, were analysed for total mercury (Hg), saturated hydrocarbons and unresolved complex mixtures (UCMs) of hydrocarbons. Results show that sediment-Hg concentration ranges from 0.01 to 1.38mgkg–1 (mean 0.20mgkg–1) and a spatial trend in Hg-content low–high–low–high, from freshwater source, to Glasgow, to estuary, is evident. In summary, sediment-Hg content is low in the upper Clyde (mean of 0.05Hg mgkg–1), whereas sediments from the Clyde in urbanised Glasgow have higher Hg concentrations (0.04 to 1.26mgkg–1; mean 0.45mgkg–1), and the inner estuary sediments contain less Hg (mean 0.06mgkg–1). The highest mean sediment Hg (0.65mgkg–1) found in the outer estuary is attributed to historical anthropogenic activities. A significant positive Spearman correlation between Hg and total organic carbon is observed throughout the river estuary (0.86; P<0.001). Comparison with Marine Scotland guidelines suggests that no sites exceed the 1.5mgkg–1 criterion (Action Level 2); 22 fall between 0.25 and 1.5mgkg–1 dry wt. (Action Level 1) and 63 are of no immediate concern (<0.25mgkg–1 dry wt.). Saturated (n-alkane) hydrocarbons in the upper Clyde are of natural terrestrial origin. By contrast, the urbanised Glasgow reaches and outer estuary are characterised by pronounced and potentially toxic UCM concentrations in sediments (380–914mg/kg and 103–247mgkg–1, respectively), suggesting anthropogenic inputs such as biodegraded crude oil, sewage discharge and/or urban run-off.

Research paper thumbnail of A comparison of batch mode and dynamic physiologically based

A fed state in vitro methodology capable of use in commercial testing laboratories has been devel... more A fed state in vitro methodology capable of use in commercial testing laboratories has been developed for measuring the human ingestion bioaccessibility of polyaromatic hydrocarbons (PAHs) in soil (Fed ORganic Estimation human Simulation Test-FOREhST). The protocol for measuring PAHs in the simulated gastro-intestinal fluids used methanolic KOH saponification followed by a combination of polymeric sorbent solid phase extraction and silica sorbent cartridges for sample clean-up and preconcentration. The analysis was carried out using high pressure liquid chromatography with fluorescence detection. The repeatability PAH bioaccessibility Paper 22/10/2012 Version 8 2 of the method, assessed by the measurement of the bioaccessibility of 6 PAHs (benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[ah]anthracene and indeno[1,2,3-c,d]pyrene) in eleven gas works soils, was c.10% RSD. The method compared well with the results from an independent dynamic human simulation reactor comprising of the stomach, duodenal and colon compartments tested on the same soils. The measured bioaccessible fraction of the soils varied from 10-60% for soils containing 10-300 mg kg-1 PAH (the sum of the six studied) with total organic carbon concentrations in the soils ranging from 1-13%. A multiple regression model showed that the PAH bioaccessible fraction could be explained using the PAH compound, the soil type and the total PAH to soil organic carbon content. The method described here has potential for site specific detailed quantitative risk assessment either to modify the risk estimation or to contribute to the risk evaluation.

Research paper thumbnail of Inductively Coupled Plasma Spectrometry

Books in soils, plants, and the environment, Oct 15, 2003

Optical Emission Spectra are observed by dispersing the radiation according to wavelength so that... more Optical Emission Spectra are observed by dispersing the radiation according to wavelength so that photons of different frequency (i)) appear in the focal plane of a spectroscopic apparatus as an array of monochromatic images of the entrance slit. These images are charac-terised by their wavelengths (7k) and called spectral lines.

Research paper thumbnail of Validation of a gravimetric PM2.5 impactor using particle sizing techniques

The London Information Office also maintains a reference collection of BGS publications, includin... more The London Information Office also maintains a reference collection of BGS publications, including maps, for consultation. We publish an annual catalogue of our maps and other publications; this catalogue is available online or from any of the BGS shops. The British Geological Survey carries out the geological survey of Great Britain and Northern Ireland (the latter as an agency service for the government of Northern Ireland), and of the surrounding continental shelf, as well as basic research projects. It also undertakes programmes of technical aid in geology in developing countries. The British Geological Survey is a component body of the Natural Environment Research Council.

Research paper thumbnail of Predictive Geochemical Mapping Using Machine Learning in Western Kenya

Social Science Research Network, 2022

Research paper thumbnail of Potential fluoride exposure from selected food crops grown in high fluoride soils in the Makueni County, south-eastern Kenya

Environmental Geochemistry and Health, 2022

Makueni County, located in south-eastern Kenya, faces challenges such as limited potable water an... more Makueni County, located in south-eastern Kenya, faces challenges such as limited potable water and restricted food supplies as the result of semi-aridity. High fluoride (F) concentrations have been reported in drinking water with resultant dental fluorosis affecting the local population. To determine the potential F exposure through the consumption of food crops grown in the area, F concentration was assessed in the main five locally grown and consumed crops. Additionally, the water-soluble F fraction was determined from 30 soil samples with mineralogical determination of 20 samples. Mean F concentration in the food crops was in the order; 700, 288, 71.2, 36.6, and 29 mg/kg in kale, cowpeas leaves, green grams, cowpeas (legume portion), and maize, respectively. The F concentration in farm soils ranged from 0 to 3.47 mg/kg (mean of 0.87 mg/kg) and showed a significant strong positive correlation (p = 0.03, r = 0.89) with F values in the crops. Apatite, muscovite, and biotite were ide...

Research paper thumbnail of Environmental baseline monitoring : Phase III final report (2017-2018)

High-quality environmental baseline monitoring data are being collected in areas around two propo... more High-quality environmental baseline monitoring data are being collected in areas around two proposed shale gas sites near Kirby Misperton, North Yorkshire and Little Plumpton Lancashire. Monitoring has now been on-going for over two years and has produced an internationally unique data set that will allow any future changes that arise from industrial activities at either or both shale gas sites to be detected and characterised, as well as providing a significant resource for future research. The monitoring includes: water quality, air quality, seismicity, ground motion, soil gas and radon in air. This report presents the results of monitoring in the Vale of Pickering, within which the Kirby Misperton shale gas site (KM8) is located, for the period April 2017–March 2018. It also includes the results of atmospheric composition measurements made near the Little Plumpton (Preston New Road) site. Earlier results and other monitoring in Lancashire are reported elsewhere and can be accesse...

Research paper thumbnail of How can oral bioaccessibility improve the human health risk assessment of inorganic contaminants? Case study: metropolitan area of Belfast

Research paper thumbnail of Influences of Contaminant Source over Oral Bioaccessibility of Potentially Toxic Elements in Belfast Topsoils

Goldschmidt2021 abstracts, 2021

Research paper thumbnail of Preface of SI:ISEG 2016

Applied Geochemistry, 2018

Research paper thumbnail of Equal abundance of odd and even n-alkanes from cycad leaves: can the carbon preference index (CPI) faithfully record terrestrial organic matter input at low latitudes?

of odd and even nalkanes from cycad leaves: can the carbon preference index (CPI) faithfully reco... more of odd and even nalkanes from cycad leaves: can the carbon preference index (CPI) faithfully record terrestrial organic matter input at low latitudes? Encephalartos (118).

Research paper thumbnail of Using 206/207Pb isotope ratios to estimate phosphorus sources in historical sediments of a lowland river system

Journal of Soils and Sediments, 2020

Purpose Engineering and dredging strategies to manage sediment, along with river-scouring, can re... more Purpose Engineering and dredging strategies to manage sediment, along with river-scouring, can reveal older sediments. These present a unique opportunity to assess past sources of phosphorus (P) inputs into river sediments. We used the sediment concentrations of P, lead (Pb) and 206/207Pb isotopes to produce ‘first-order’ estimates of the source (diffuse agricultural or sewage treatment) of phosphorus. Materials and methods Sediment cores (n = 30) were collected from the length of the non-tidal River Nene, a lowland river in eastern England. Cores were analysed for sediment elemental concentrations and Pb isotopes. Principal component analysis and linear regression modelling were used to assess the relationships between P, Pb and Pb isotopes. Monte-Carlo simulations and boot-strapping were undertaken to estimate, with 95% confidence intervals, the source of P in these sediments. Results and discussion Analysis of the relationships between PTotal, PbTotal and 206/207Pb isotope ratios...

Research paper thumbnail of Assessing the influence of the industrial past on an urban environment - what does the soil geochemistry?

Research paper thumbnail of Technical Guidance Sheet (TGS) on normal levels of contaminants in English soils : copper (Cu) : technical guidance sheet TGS03, July 2012

Research paper thumbnail of Technical Guidance Sheet (TGS) on normal levels of contaminants in English soils : Benzo(a)pyrene (BaP) : technical guidance sheet TGS04, July 2012

Both the NSI (XRFS) and G-BASE data sets are derived from a soil sample that has been aggregated ... more Both the NSI (XRFS) and G-BASE data sets are derived from a soil sample that has been aggregated (composited) from a number of subsamples collected over the area of a site, rather than a single point sample. In the case of NSI this is 25 cores (subsamples) from a 20-m square (McGrath and Loveland 1992) whereas G-BASE is 5 cores, also from a 20-m square (Johnson et al. 2005; Fordyce et al. 2005). If a sample is collected as a single core, and the result is compared to the NBC, it is important to be aware that short-range variation (which can be substantial) for the single core sample will be potentially much greater than for the samples from which the NBC values are derived (Lark, 2012). Soil samples used to calculate the Cu NBCs have been collected from the top 15 cm of the mineral soil profile (hence they are referred to as topsoils). When the sample is collected from a site covered with vegetation the surface organic layers (leaf litter) do not form part of the sample collected. Any recently deposited airborne particulates that have not yet migrated into the soil profile will not be sampled and surface organic material, which has the capacity to fix some contaminants from atmospheric deposition, is not included as part of the sample. In urban areas the top 15 cm will be expected to have been modified by historical urban land uses and, in rural agricultural areas, where relevant, will be within the ploughed horizon. Surveys targeting recent airborne pollution added to the soil will generally only collect from the top 2 cm of the profile in order to bias the soil results toward the airborne pollutant inputs. Such data has not been used in the NBC calculations

Research paper thumbnail of Characterization of oral bioaccessibility of Potentially Toxic Elements (PTEs) in urban area of Belfast

Research paper thumbnail of ORAL BIOACCESSIBILITY OF POTENTIALLY TOXIC ELEMENTS (PTEs) IN URBAN AREA OF BELFAST

A literature survey has shown that no study has investigated the oral bioaccessibility of PTEs in... more A literature survey has shown that no study has investigated the oral bioaccessibility of PTEs in Nigeria dusts. Studies on human health risk of PTEs from urban Nigeria dust have been based only on total elemental concentrations. Whilst this protocol is useful in assessing human health of PTEs, it could lead to an over estimation of the risk considering the elemental sequestration in the dust samples. This study deviated from previous studies by examining the total concentrations as well as the oral bioaccessibility of 8 PTEs in 15 urban dust samples collected from Abakaliki, Ebonyi State, Nigeria. The result showed that high concentrations of Pb (ranging from 236-1815 mg/kg) were observed in 5 locations. The Unified Bioaccessibility Method (UBM) was used to investigate the oral bioaccessibility of these PTEs in the urban dust samples. The result revealed that all the PTEs were more bioaccessible in the gastric phase that the gastric + intestinal phase. The lead tolerable daily intake (TDI), as well as the bioaccessible TDI, was computed and results compared with a guideline value. © JASEM

Research paper thumbnail of Soil mineralogy and its effect on oral bioaccessibility of Ni and Cr in soils overlying basalt lavas, Northern Ireland

Research paper thumbnail of Stream sediment background concentrations in mineralised catchments in Northern Ireland: assessment of ‘pressures’ on water bodies in fulfilment of Water Framework Directive objectives

An approach for deriving sediment background metal and metalloid element concentrations using sys... more An approach for deriving sediment background metal and metalloid element concentrations using systematically collected geochemical survey data is demonstrated in the mineralised area associated with the Ordovician-Silurian rocks in counties Down and Armagh in Northern Ireland. Operationally-defined background ranges can be used for improving the assessment of the environmental pressures posed by historical mining on impacted catchments and establishing feasible catchment restoration goals. Deriving pre-mining baselines provides essential information for any proposed mineral development project, with direct benefit to the mineral sector and industry.

Research paper thumbnail of Technical Guidance Sheet (TGS) on normal levels of contaminants in English soils : cadmium (Cd) : technical guidance sheet TGS06, July 2012

Research paper thumbnail of Mercury, n-alkane and unresolved complex mixture hydrocarbon pollution in surface sediment across the rural–urban–estuarine continuum of the River Clyde, Scotland, UK

Earth and Environmental Science Transactions of The Royal Society of Edinburgh, Jun 1, 2017

ABSTRACTSurface sediments (n=85) from a 160-km river-estuarine transect of the Clyde, UK, were an... more ABSTRACTSurface sediments (n=85) from a 160-km river-estuarine transect of the Clyde, UK, were analysed for total mercury (Hg), saturated hydrocarbons and unresolved complex mixtures (UCMs) of hydrocarbons. Results show that sediment-Hg concentration ranges from 0.01 to 1.38mgkg–1 (mean 0.20mgkg–1) and a spatial trend in Hg-content low–high–low–high, from freshwater source, to Glasgow, to estuary, is evident. In summary, sediment-Hg content is low in the upper Clyde (mean of 0.05Hg mgkg–1), whereas sediments from the Clyde in urbanised Glasgow have higher Hg concentrations (0.04 to 1.26mgkg–1; mean 0.45mgkg–1), and the inner estuary sediments contain less Hg (mean 0.06mgkg–1). The highest mean sediment Hg (0.65mgkg–1) found in the outer estuary is attributed to historical anthropogenic activities. A significant positive Spearman correlation between Hg and total organic carbon is observed throughout the river estuary (0.86; P<0.001). Comparison with Marine Scotland guidelines suggests that no sites exceed the 1.5mgkg–1 criterion (Action Level 2); 22 fall between 0.25 and 1.5mgkg–1 dry wt. (Action Level 1) and 63 are of no immediate concern (<0.25mgkg–1 dry wt.). Saturated (n-alkane) hydrocarbons in the upper Clyde are of natural terrestrial origin. By contrast, the urbanised Glasgow reaches and outer estuary are characterised by pronounced and potentially toxic UCM concentrations in sediments (380–914mg/kg and 103–247mgkg–1, respectively), suggesting anthropogenic inputs such as biodegraded crude oil, sewage discharge and/or urban run-off.

Research paper thumbnail of A comparison of batch mode and dynamic physiologically based

A fed state in vitro methodology capable of use in commercial testing laboratories has been devel... more A fed state in vitro methodology capable of use in commercial testing laboratories has been developed for measuring the human ingestion bioaccessibility of polyaromatic hydrocarbons (PAHs) in soil (Fed ORganic Estimation human Simulation Test-FOREhST). The protocol for measuring PAHs in the simulated gastro-intestinal fluids used methanolic KOH saponification followed by a combination of polymeric sorbent solid phase extraction and silica sorbent cartridges for sample clean-up and preconcentration. The analysis was carried out using high pressure liquid chromatography with fluorescence detection. The repeatability PAH bioaccessibility Paper 22/10/2012 Version 8 2 of the method, assessed by the measurement of the bioaccessibility of 6 PAHs (benz[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[ah]anthracene and indeno[1,2,3-c,d]pyrene) in eleven gas works soils, was c.10% RSD. The method compared well with the results from an independent dynamic human simulation reactor comprising of the stomach, duodenal and colon compartments tested on the same soils. The measured bioaccessible fraction of the soils varied from 10-60% for soils containing 10-300 mg kg-1 PAH (the sum of the six studied) with total organic carbon concentrations in the soils ranging from 1-13%. A multiple regression model showed that the PAH bioaccessible fraction could be explained using the PAH compound, the soil type and the total PAH to soil organic carbon content. The method described here has potential for site specific detailed quantitative risk assessment either to modify the risk estimation or to contribute to the risk evaluation.

Research paper thumbnail of Inductively Coupled Plasma Spectrometry

Books in soils, plants, and the environment, Oct 15, 2003

Optical Emission Spectra are observed by dispersing the radiation according to wavelength so that... more Optical Emission Spectra are observed by dispersing the radiation according to wavelength so that photons of different frequency (i)) appear in the focal plane of a spectroscopic apparatus as an array of monochromatic images of the entrance slit. These images are charac-terised by their wavelengths (7k) and called spectral lines.

Research paper thumbnail of Validation of a gravimetric PM2.5 impactor using particle sizing techniques

The London Information Office also maintains a reference collection of BGS publications, includin... more The London Information Office also maintains a reference collection of BGS publications, including maps, for consultation. We publish an annual catalogue of our maps and other publications; this catalogue is available online or from any of the BGS shops. The British Geological Survey carries out the geological survey of Great Britain and Northern Ireland (the latter as an agency service for the government of Northern Ireland), and of the surrounding continental shelf, as well as basic research projects. It also undertakes programmes of technical aid in geology in developing countries. The British Geological Survey is a component body of the Natural Environment Research Council.

Research paper thumbnail of Predictive Geochemical Mapping Using Machine Learning in Western Kenya

Social Science Research Network, 2022

Research paper thumbnail of Potential fluoride exposure from selected food crops grown in high fluoride soils in the Makueni County, south-eastern Kenya

Environmental Geochemistry and Health, 2022

Makueni County, located in south-eastern Kenya, faces challenges such as limited potable water an... more Makueni County, located in south-eastern Kenya, faces challenges such as limited potable water and restricted food supplies as the result of semi-aridity. High fluoride (F) concentrations have been reported in drinking water with resultant dental fluorosis affecting the local population. To determine the potential F exposure through the consumption of food crops grown in the area, F concentration was assessed in the main five locally grown and consumed crops. Additionally, the water-soluble F fraction was determined from 30 soil samples with mineralogical determination of 20 samples. Mean F concentration in the food crops was in the order; 700, 288, 71.2, 36.6, and 29 mg/kg in kale, cowpeas leaves, green grams, cowpeas (legume portion), and maize, respectively. The F concentration in farm soils ranged from 0 to 3.47 mg/kg (mean of 0.87 mg/kg) and showed a significant strong positive correlation (p = 0.03, r = 0.89) with F values in the crops. Apatite, muscovite, and biotite were ide...

Research paper thumbnail of Environmental baseline monitoring : Phase III final report (2017-2018)

High-quality environmental baseline monitoring data are being collected in areas around two propo... more High-quality environmental baseline monitoring data are being collected in areas around two proposed shale gas sites near Kirby Misperton, North Yorkshire and Little Plumpton Lancashire. Monitoring has now been on-going for over two years and has produced an internationally unique data set that will allow any future changes that arise from industrial activities at either or both shale gas sites to be detected and characterised, as well as providing a significant resource for future research. The monitoring includes: water quality, air quality, seismicity, ground motion, soil gas and radon in air. This report presents the results of monitoring in the Vale of Pickering, within which the Kirby Misperton shale gas site (KM8) is located, for the period April 2017–March 2018. It also includes the results of atmospheric composition measurements made near the Little Plumpton (Preston New Road) site. Earlier results and other monitoring in Lancashire are reported elsewhere and can be accesse...

Research paper thumbnail of How can oral bioaccessibility improve the human health risk assessment of inorganic contaminants? Case study: metropolitan area of Belfast

Research paper thumbnail of Influences of Contaminant Source over Oral Bioaccessibility of Potentially Toxic Elements in Belfast Topsoils

Goldschmidt2021 abstracts, 2021

Research paper thumbnail of Preface of SI:ISEG 2016

Applied Geochemistry, 2018

Research paper thumbnail of Equal abundance of odd and even n-alkanes from cycad leaves: can the carbon preference index (CPI) faithfully record terrestrial organic matter input at low latitudes?

of odd and even nalkanes from cycad leaves: can the carbon preference index (CPI) faithfully reco... more of odd and even nalkanes from cycad leaves: can the carbon preference index (CPI) faithfully record terrestrial organic matter input at low latitudes? Encephalartos (118).

Research paper thumbnail of Using 206/207Pb isotope ratios to estimate phosphorus sources in historical sediments of a lowland river system

Journal of Soils and Sediments, 2020

Purpose Engineering and dredging strategies to manage sediment, along with river-scouring, can re... more Purpose Engineering and dredging strategies to manage sediment, along with river-scouring, can reveal older sediments. These present a unique opportunity to assess past sources of phosphorus (P) inputs into river sediments. We used the sediment concentrations of P, lead (Pb) and 206/207Pb isotopes to produce ‘first-order’ estimates of the source (diffuse agricultural or sewage treatment) of phosphorus. Materials and methods Sediment cores (n = 30) were collected from the length of the non-tidal River Nene, a lowland river in eastern England. Cores were analysed for sediment elemental concentrations and Pb isotopes. Principal component analysis and linear regression modelling were used to assess the relationships between P, Pb and Pb isotopes. Monte-Carlo simulations and boot-strapping were undertaken to estimate, with 95% confidence intervals, the source of P in these sediments. Results and discussion Analysis of the relationships between PTotal, PbTotal and 206/207Pb isotope ratios...

Research paper thumbnail of Assessing the influence of the industrial past on an urban environment - what does the soil geochemistry?

Research paper thumbnail of Technical Guidance Sheet (TGS) on normal levels of contaminants in English soils : copper (Cu) : technical guidance sheet TGS03, July 2012

Research paper thumbnail of Technical Guidance Sheet (TGS) on normal levels of contaminants in English soils : Benzo(a)pyrene (BaP) : technical guidance sheet TGS04, July 2012

Both the NSI (XRFS) and G-BASE data sets are derived from a soil sample that has been aggregated ... more Both the NSI (XRFS) and G-BASE data sets are derived from a soil sample that has been aggregated (composited) from a number of subsamples collected over the area of a site, rather than a single point sample. In the case of NSI this is 25 cores (subsamples) from a 20-m square (McGrath and Loveland 1992) whereas G-BASE is 5 cores, also from a 20-m square (Johnson et al. 2005; Fordyce et al. 2005). If a sample is collected as a single core, and the result is compared to the NBC, it is important to be aware that short-range variation (which can be substantial) for the single core sample will be potentially much greater than for the samples from which the NBC values are derived (Lark, 2012). Soil samples used to calculate the Cu NBCs have been collected from the top 15 cm of the mineral soil profile (hence they are referred to as topsoils). When the sample is collected from a site covered with vegetation the surface organic layers (leaf litter) do not form part of the sample collected. Any recently deposited airborne particulates that have not yet migrated into the soil profile will not be sampled and surface organic material, which has the capacity to fix some contaminants from atmospheric deposition, is not included as part of the sample. In urban areas the top 15 cm will be expected to have been modified by historical urban land uses and, in rural agricultural areas, where relevant, will be within the ploughed horizon. Surveys targeting recent airborne pollution added to the soil will generally only collect from the top 2 cm of the profile in order to bias the soil results toward the airborne pollutant inputs. Such data has not been used in the NBC calculations