This dataset represents the raw reads from sequencing the V4 hyper-variable region of the 16S rRNA gene on an Illumina MiSeq platform. The samples are filtered groundwater samples from 8 boreholes from a sandy-dominated site and a clay-dominated site in Cambodia that show arsenic concentrations above the WHO recommended limit, and were collected in May 2019.

The BGS Estimated Ambient Background Soil Chemistry Scotland digital soil chemistry data indicates the estimated geometric mean topsoil concentrations (mg kg-1) of Arsenic (As), Cadmium (Cd), Chromium (Cr), Nickel (Ni) and Lead (Pb). The soil chemistry data is based on GBASE (Geochemical Baseline Survey of the Environment) stream sediment data converted to top soil equivalent potentially harmful element(PHE) concentrations. This dataset covers Scotland but data is available for the whole of Great Britain, with the exception of the London area where an inadequate number of geochemical samples are available at the moment.

Data on gas composition in headspace of borehole NB04. Contains 11 columns of data taken from the headspace of borehole NB04 (at the clay-dominated site) using a GasClam 2.0 (Salamander Group, UK) that continuously measure temperature, atmospheric pressure, borehole pressure, and the percentage of carbon dioxide, oxygen, and methane in the borehole. All data collection for the GOAM project was performed on the same sites located in the Kien Svay district of northern Kandal Province, Cambodia, southeast of Phnom Penh. These sites are referred to as "clay-dominated" and "sand-dominated" in reference to the known lithology and are known for high arsenic concentrations (Richards et al., 2017). Each site contained four 18 m boreholes installed in January 2019 using manual drilling described in Richards et al (2015), spaced evenly about ~1.5 m apart. The boreholes that were located at the clay-dominated site are referred to NB01, NB02, NB03 and NB04. The boreholes that were located at the sand-dominated site are referred to as NB05, NB06, NB07 and NB08. The data taken are from the headspace of borehole NB04 (at the clay-dominated site) This file contains part of the data produced for NERC grant NE/P01304X/1 - called Genetic and molecular basis of organic-arsenic-microbe interactions in arsenic prone aquifers ("GOAM") project. References: Richards, L. A., Lapworth, D. J., Magnone, D., Gooddy, D. C., Chambers, L., Williams, P. J., van Dongen, B. E., Polya, D. A. Dissolved Organic Matter Tracers Reveal Contrasting Characteristics across High Arsenic Aquifers in Cambodia: A Fluorescence Spectroscopy Study. Geoscience Frontiers 2019, 10 (5), 1653-1667. Richards, L. A., Magnone, D., Sovann, C., Kong, C., Uhlemann, S., Kuras, O., van Dongen, B. E., Ballentine, C. J., Polya, D. A. High Resolution Profile of Inorganic Aqueous Geochemistry and Key Redox Zones in an Arsenic Bearing Aquifer in Cambodia. Science of The Total Environment 2017, 590-591, 540-553. Richards, L. A., Magnone, D., van Dongen, B. E., Ballentine, C. J., Polya, D. A. Use of Lithium Tracers to Quantify Drilling Fluid Contamination for Groundwater Monitoring in Southeast Asia. Applied Geochemistry 2015, 63, 190-202.

These are groundwater geochemical data taken from two sites in the Kien Svay district of northern Kandal Province, Cambodia, southeast of Phnom Penh. These sites are referred to as “clay-dominated” and “sand-dominated” in reference to the known lithology and are known for high arsenic concentrations (Richards et al., 2017). Each site contained four 18 m boreholes installed in January 2019 using manual drilling described in Richards et al (2015), spaced evenly about ~1.5 m apart. The boreholes that were located at the clay-dominated site are referred to NB01, NB02, NB03 and NB04. The boreholes that were located at the sand-dominated site are referred to as NB05, NB06, NB07 and NB08. Two sampling campaigns were carried out: 6th-12th May 2019 (pre-monsoon season), and 27th-31st January 2020 (post-monsoon season). References: Richards, L. A., Magnone, D., Sovann, C., Kong, C., Uhlemann, S., Kuras, O., van Dongen, B. E., Ballentine, C. J., Polya, D. A. High Resolution Profile of Inorganic Aqueous Geochemistry and Key Redox Zones in an Arsenic Bearing Aquifer in Cambodia. Science of The Total Environment 2017, 590–591, 540–553. Richards, L. A., Magnone, D., van Dongen, B. E., Ballentine, C. J., Polya, D. A. Use of Lithium Tracers to Quantify Drilling Fluid Contamination for Groundwater Monitoring in Southeast Asia. Applied Geochemistry 2015, 63, 190–202.

2 published papers from NERC grant NE/G016879/1. Palaeosol Control of Arsenic Pollution:The Bengal Basin in West Bengal, India by by U. Ghosal, P.K. Sikdar, and J.M. McArthur. Tracing recharge to aquifers beneath an Asian megacity with Cl/Br and stable isotopes: the example of Dhaka, Bangladesh by M. A. Hoque, J. M. McArthur, P. K. Sikdar, J. D. Ball and T. N. Molla (DOI 10.1007/s10040-014-1155-8)

THIS DATASET HAS BEEN WITHDRAWN **This dataset was created for the "Britain beneath our feet" atlas using information extracted from the Geochemical Baseline Survey Of The Environment (G-BASE) For The UK . For Arsenic in soil data please see Geochemical Baseline Survey Of The Environment (G-BASE) For The UK ** Geochemical Baseline Survey Of The Environment (G-BASE) coverage for arsenic in soil. The G-BASE programme involves systematic sampling and the determination of chemical elements in samples of stream sediment, stream water and, locally, soil, to build up a picture of the surface chemistry of the UK. The average sample density for stream sediments and water is about one site per 1.5-2km square. Analytical precision is high with strict quality control to ensure countrywide consistency. Results have been standardised to ensure seamless joins between geochemical sampling campaigns. The data provide baseline information on the natural abundances of elements, against which anomalous values due to such factors as mineralisation and industrial contamination may be compared. Published in Britain beneath our feet atlas.

The BGS digital estimated urban soil chemistry data (GB_EstimatedUrbanSoilChemistry_v3) indicates the estimated geometric mean concentrations (mg kg-1) of Arsenic (As), Cadmium (Cd), Chromium (Cr), Nickel (Ni) and Lead (Pb) in topsoil derived by spatial interpolation of the point source urban soil chemistry data. The information is relevant for the first stage of any assessment of risks to human health required by regulatory authorities in relation to land use and also assessing ecological risks. Estimated topsoil PHE (Potentially Harmful Element) concentrations above respective SGVs (Soil Guideline Value) do not necessarily imply a significant health risk but they do highlight the need to consider whether or not there may be a risk. Comparison of this spatially referenced geochemical data set with information on current or historic land use and geological information might help environmental professionals decide whether high PHE concentrations in topsoils can be attributed to geogenic or anthropogenic sources. The dataset is based on, and limited to, an interpretation of the records in the possession of the BGS at the time the dataset was created. An indication of high estimated PHE concentrations in soil does not necessarily mean that an individual site will have a high PHE concentration. Topsoil concentrations in urban areas are frequently characterised by strong spatial variation over short distances so this data should be interpreted and used with caution. The original urban topsoil samples were collected and analysed as part of the BGS Geochemical Baseline Survey of the Environment (G-BASE) project.

The BGS digital Measured Urban Soil Chemistry data comprises the locations and concentrations (mg kg-1) of Arsenic (As), Cadmium (Cd), Chromium (Cr), Nickel (Ni) and Lead (Pb) in urban topsoil samples. The data is derived from the national, high resolution urban soil geochemical data from the BGS Geochemical Baseline Survey of the Environment (G-BASE) project. The information is relevant for the first stage of any assessment of risks to human health required by regulatory authorities in relation to land use and also for assessing ecological risk. Although point source PHE (Potentially Harmful Element) concentrations above respective SGVs (Soil Guideline Value) do not necessarily imply a significant health risk, they do highlight the need to consider whether or not there may be a risk. The urban soil chemistry data can be used to assist Local Planning Authorities to identify those areas where a risk assessment may need to be carried out by developers. Comparison of this spatially referenced geochemical data with information on current or historic land use and geological information might help environmental professionals decide whether high PHE concentrations in topsoils can be attributed to geogenic or anthropogenic sources. The point source data is based on an interpretation of the records in the possession of the BGS at the time the dataset was created.

The dataset comprise hydrogeochemical, isotopic and environmental geophysics data from surface waters and groundwater and sediments from scientific boreholes drilled into arsenic-prone aquifers in the Mekong River Basin. The data is divided into 5 categories: Geophysical data Hydrogeochemical data Isotopic data Sedimentary data Outreach and Dissemination Publications to date - open access linkages The data pertain to samples obtained from northern Kandal province just south of Phnom Penh in Cambodia. The data were collected over the period 2013-2016. The hydrogeochemical data were obtained by one of more of (i) in situ analytical techniques; or (ii) instrumental geochemical techniques, notably IC, ICP-AES, ICP-MS and GC-MS in the Manchester Analytical Geochemistry Unit, University of Manchester following methods as described in Richards et al. (2015, 2017). The geophysical data were obtained as described in Uhlemann et al. (2017). The data were obtained as part of a project funded by NERC Standard Research Grant NE/J023833/1 the major purpose of which was to determine the extent to which surface derived organics may be driving arsenic mobilisation in shallow circum-Himalayan aquifers, an exemplar of which is norther Kandal Province's largely Holocene aquifers to which these data refer. The data were obtained and interpreted by the University of Manchester except as follows: environmental geophysics data were obtained and interpreted by Oliver Kuras and Sebastian Uhlemann of the British Geological Survey GTOM team; tritium data were generated by Jurgen Sultenfuss of the University of Bremen; oxygen and hydrogen isotope data by SUERC, East Kilbride and carbon-14 data by the NERC Radiocarbon Laboratory at East Kilbride.

This dataset has now been superseded, please see the Estimated Urban Soil Chemistry dataset. There are two themes to BGS urban soil chemistry, the point source dataset and the estimated dataset. The point source urban soil chemistry data comprises the locations and concentrations (mg kg-1) of Arsenic (As). Cadmium (Cd), Chromium (Cr), Nickel (Ni) and Lead (Pb) in urban topsoil samples. The Estimated Urban Soil Chemistry data indicates the estimated geometric mean concentrations (mg kg-1) of As, Cd, Cr, Ni and Pb in topsoil derived by spatial interpolation of the Point Source Urban Soil Chemistry data. Both urban soil chemistry datasets are derived from high resolution urban soil geochemical data from the BGS Geochemical Baseline Survey of the Environment (G-BASE) project. The Urban Soil Chemistry data can be used to assist Local Planning Authorities to identify those areas where a risk assessment may need to be carried out by developers. Comparison of this spatially referenced geochemical data with information on current or historic land use and geological information might help environmental professionals decide whether high PHE concentrations in topsoils can be attributed to geogenic or anthropogenic sources. The dataset is based on, and limited to, an interpretation of the records in the possession of the BGS at the time the dataset was created.