London Earth Topsoil Chemical Results: User Guide
Contents
1. ee ee eee CR CIC E 1 4 GSD 7 ees eee Ree es es eee eee OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 e ET AR UM i a S e Table 4 2 Elements by XRF WDT Cert Cert CRM ID Cert Na20 Cert MgO AI203 Cert AI203 P205 P205 Se DINEENENCGCENNCICND GIZCULOGNMNGUETEXCID _ _ _ _ CRM ID 503 5 not GSD 7 detected no data Table4 3 Elements by XRF WDM Table 4 Summary of primary reference material results for London Earth soil samples XRFS analyses S13B Chart of Ni 484 UCL 48 002 474 45 657 s m Individual Value LCL 43 311 434 is 8 7 5 5 10 OA A Observation Figure 2 Example of a time series plot Shewhart plot used to indicate the precision and accuracy of elemental analyses between different analytical batches This chart shows repeated analyses for Ni in reference soil S13B Green line shows accepted value x red lines x 2 std dev Duplicate samples i e separate samples that have been collected from the same sampling site and replicate samples i e a sample split into two samples in the laboratory can be used to i2. 48 29469 2094 3 5 257148 85 2 15 80002 505 6 142 6825 5325 5 292 2913 10095 2 791615 27 6 1 670454 29 4 8 637098 160 9 0 604414 19 6 5 815867 119 19 04873 148 6 40 54883 601 2 7 62795 132 9 85 11562 1446 4 3 020127 146 7 8 874716 561 2 8 727336 122 8 2 044726 25 8 0 896897 8 8 2 30664 37 1 0 595945 9 5 6 203868 316 8 1 369056 33 8 0 640149 26 2 430 4443 10000 2 789603 70 5 5 896254 456 5 0 875289 6 4 0 127707 1 6 0 42341 4 2 757696 20 8 10 38328 100 0 226831 Table 3 Summary statistics of London Earth topsoil results 4 49 ION C NN ee ee OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 1 2 27 ie La E Table 4 1 Elements by XRF ED Cert Cert Cert Cert K20 K20 CaO CaO TiO2 TiO2 MnO Cert MnO Fe203 Fe203 5 LKSD 1 1 10 12 14 10 80 0 448 0 500 0 093 0 100 LKSD 4 0 76 0 80 0 299 0 400 0 068 0 100 4 20 4 10 1 7 85 pev eur tone SUCI wer Besse m uns e a Bees C e e ING IE ups un
3. describes the format of the results and details how the data was conditioned before delivery OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 Introduction Founded in 1835 the British Geological Survey BGS is the world s oldest national geological survey and the United Kingdom s premier centre for earth science information and expertise The BGS provides expert services and impartial advice in all areas of geoscience Our client base is drawn from the public and private sectors both in the UK and internationally Our innovative digital data products aim to help describe the ground surface and what s beneath across the whole of Great Britain These digital products are based on the outputs of the BGS survey and research programmes and our substantial national data holdings This data coupled with our in house Geoscientific knowledge are combined to provide products relevant to a wide range of users in central and local government insurance and housing industry engineering and environmental business and the British public Further information on all the digital data provided by the BGS can be found on our website at http www bgs ac uk products or by contacting Central Enquiries British Geological Survey Kingsley Dunham Centre Keyworth Nottingham NG12 5GG Direct tel 44 0 115 936 3143 Fax 44 0 115 9363150 email enquiries bgs ac uk 2 About the London Earth Dataset Data Described LondonEarth_Topsoil_XRFS_v1 xl
4. 9 British BG i 2 Geological Survey 1855 NATURAL ENVIRONMENT RESEARCH COUNCIL London Earth Topsoil Chemical Results User Guide Land use planning and development Programme Open Report OR 1 1 035 BRITISH GEOLOGICAL SURVEY LAND USE PLANNING AND DEVELOPMENT PROGRAMME OPEN REPORT OR 11 035 London Earth Topsoil Chemical Results User Guide C C Johnson A Scheib amp T R Lister The National Grid and other Ordnance Survey data are used with the permission of the Controller of Her Majesty s Stationery Office Licence No 100017897 2010 Keywords Report geochemical sampling chemical analysis London Bibliographical reference JOHNSON C C SCHEIB A LISTER T R 2010 London Earth Topsoil Chemical Results User Guide British Geological Survey Open Report OR 11 035 l6pp Copyright in materials derived from the British Geological Survey s work is owned by the Natural Environment Research Council NERC and or the authority that commissioned the work You may not copy or adapt this publication without first obtaining permission Contact the BGS Intellectual Property Rights Section British Geological Survey Keyworth e mail ipr bgs ac uk You may quote extracts of a reasonable length without prior permission provided a full acknowledgement is given of the source of the extract Maps and diagrams in this book use topography based on Ordnance Survey mapping NERC 2011 All rights reserved K
5. erui Acknowled i ndi S i jw Ree 1 Unt Ct Oh 2 2 About the London Earth ee eee ee eese eee eese senos sees eese eesesossse sese eeeeeesssssssss 2 Del eerte eh 3 2 2 Sample preparati n and nce oh cue wassup pees 4 231 eate p RUE 4 TUnusobConceniralolrsdosdesc dias a en ipia 5 2 3 Fieldsin the results database dab eon 5 2 6 o Data GC OMAN OBI auod ord edendi ede beue 6 3 Licensing Information ament teet eser 1 2 Summary This report describes London Earth Dataset specifically the file LondonEarth Topsoil XRFS v1 xlsx It describes how the sample data were collected prepared and analysed
6. number of sites indicates the number of locations where duplicate and replicate samples were collected Those sites where element results were below detection are excluded from the ANOVA analysis 10 OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 3 Licensing Information The British Geological Survey does not sell its digital mapping data to external parties Instead BGS grants external parties a licence to use this data subject to certain standard terms and conditions In general a licence fee will be payable based on the type of data the number of users and the duration years of a licence recipients of a licence potential licensees are required to return a signed digital data licence document to us before authorisation for release of BGS digital data is given In general terms a BGS digital data licensee will be permitted to e make internal use of the dataset s e allow a specified number of internal users to access use the data the number of users will be agreed with the licensee and specified in the licence document for the purposes of their day to day internal activities e reproduce extracts from the data up to A3 for use in external analogue paper hard copy or non queryable electronic e g secured pdf format to meet a public task duty fulfil a statutory requirement and or as part of academic or other non commercial research But will not be permitted to provide a bureau service for others
7. wt 0 01 Sr strontium mg kg 1 0 Ga gallium mg kg 1 0 Ta tantalum mg kg 1 0 Ge germanium mg kg 0 5 Th thorium mg kg 0 7 Hf hafnium mg kg 1 0 TiO titanium wt 0 01 Hg mercury mg kg 0 5 TI thallium mg kg 0 5 I iodine mg kg 0 5 U uranium mg kg 0 5 potassium wt 0 01 V vanadium mg kg 3 0 La lanthanum mg kg 1 0 W tungsten mg kg 0 6 MgO magnesium wt 0 03 Y yttrium mg kg 1 0 MnO manganese wt 0 005 Yb ytterbium mg kg 1 5 Mo molybdenum mg kg 0 2 Zn zinc mg kg 1 3 Na2O sodium wt 0 3 Zr zirconium mg kg 1 0 LLD lower limit of detection Table 1 List of elements reported for the London Earth topsoils following determination by XRFS 2 2 SAMPLE PREPARATION AND ANALYSIS Samples were prepared at the BGS laboratories After drying 35 the samples were sieved through a nylon sieve to give a lt 2 mm fraction A 50 g subsample of this fraction was pulverised in an agate ball mill to create a homogeneous sample used to make a pressed powder pellet prior to XRFS analysis Samples were analysed by XRFS which gives total element concentrations in the soil samples Several different XRFS instruments were used wave dispersive and energy dispersive to determine 53 chemical elements Fifty of these elements are listed in Table 1 three elements chlorine indium In and tellurium Te are excluded from the released data set as the majority gt 95wt of the results for
8. SE The Results spreadsheet contains five columns before the element results for the elements in the next 50 columns The first row of data gives the column names Descriptive statistics for all the fields are given in Table 3 Column A Project Code Two character code to identify the project collecting the samples For London Earth two codes are used namely 64 and 65 The 64 code represents samples collected before the start of the main London Earth project in 2008 Column B Site Number An integer number between 1 and 9999 giving the number assigned to the soil sampling site A combination of the Project Code and the Site Number to give a six character number e g 641304 650001 provides a unique id for the sample and is a key field Column C Date Date the site was sampled in standard date format dd mm yyyy Column D Easting British National Grid Easting x co ordinate in metres Column E Northing British National Grid Northing y co ordinate in metres Columns F BC Fifty columns of element results with column header as chemical symbol which for the major elements is expressed as an oxide 5 OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 2 6 DATA CONDITIONING The results received from the laboratory contain control samples replicates duplicates and reference materials which are used to assess the quality of the results These control samples are removed from the data set and are no
9. a is indicated in the Excel file by colour highlights and fonts as shown in Table 2 Colour format Signifies User Action 56 7 No Quality issues None 25 4 This result is associated with a qualifier Be aware that the result is qualified Data of dubious quality with significant Pay careful attention to what the quality issue s issue is and if necessary don t use results Results lt 0 Be aware that the result could give problems in some statistical or plotting packages null value Be aware that no result is present though transferring to some software packages could erroneously reset this to 0 25 Result is at the upper limit of detection Be aware that this result has some quality issue but is unlikely to restrict its use 10 Generally a data issue relating to representation of results below limits of detection Table 2 Explanation of the colour formatting in the Excel spreadsheet Results used to indicate data quality issues 2 4 UNITS OF CONCENTRATION The units of concentration for elements are shown in Table 1 For trace elements these are mg kg i e mg kg and for the major elements these are wt i e expressed as a percentage weight of the sample Geochemists also use the old notation of ppm parts per million which is equivalent to 1 mg kg and express the major elements in terms of oxides e g 2 2 etc 2 5 FIELDS IN THE RESULTS DATABA
10. cence the BGS Intellectual Property Rights IPR section will be happy to discuss this with you and can be contacted through the following email address iprdigital 9 bgs ac uk BGS IPR will usually be able to provide reassurance that the licence will cover individual user requirements and or to include additional special conditions in the licence documentation addressing specific requirements within BGS s permitted usage 11 OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 Further Information British Geological Survey holds most of the references listed below and copies may be obtained via the library service subject to copyright legislation contact libuser bgs ac uk for details The library catalogue is available at http geolib bgs ac uk London Earth Project G BASE web site www gs ac uk gbase londonearth G BASE urban soil chemistry data APPLETON J D 2011 User Guide for British Geological Survey Urban Soil Chemistry dataset British Geological Survey 24 IR 11 039 unpublished Field sampling manual JOHNSON C C 2005 2005 G BASE field procedures manual British Geological Survey 65pp IR 05 097 Unpublished Data conditioning procedures LISTER T R AND JOHNSON C C 2005 G BASE data conditioning procedures for stream sediment and soil chemical analyses British Geological Survey 85pp IR 05 150 Unpublished JOHNSON 2011 Understanding the quality of chemical data from t
11. d but these samples are not routinely analysed The surface and deep soils are archived at the National Geoscience Data Centre NGDC in Keyworth along with the excess topsoil samples At each site samplers recorded comprehensive information about the sample and location including information such as soil texture land use and observed contamination This field information is available as the field database and can be made available on request to those who have a licence to use the results British National Grid coordinates were determined at site using a GPS and recorded to the nearest metre though in reality the spatial error is estimated at 50 m Element Oxid i Element Oxid e e Ag silver mg kg 0 5 Nb niobium mg kg 1 0 Al O3 aluminium wt 0 2 Nd neodymium mg kg 4 0 AS arsenic mg kg 2 4 Ni nickel mg kg 1 3 Ba barium mg kg 1 0 P205 phosphorous wt 0 05 Bi bismuth mg kg 0 3 Pb lead mg kg 1 3 Br bromine mg kg 0 8 Rb rubidium mg kg 1 0 CaO calcium wt 0 05 5 sulphur mg kg 1000 Cd cadmium mg kg 0 5 Sb antimony mg kg 0 5 Ce cerium mg kg 1 0 Sc scandium mg kg 3 0 Co cobalt mg kg 1 5 Se selenium mg kg 0 2 OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 Cr chromium mg kg 3 0 SiO silicon wt 0 1 Cs caesium mg kg 1 0 Sm samarium mg kg 3 0 Cu copper mg kg 1 3 Sn tin mg kg 0 5 iron
12. eyworth Nottingham British Geological Survey 2011 BRITISH GEOLOGICAL SURVEY The full range of our publications is available from BGS shops at Nottingham Edinburgh London and Cardiff Welsh publications only see contact details below or shop online at www geologyshop com 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 British Geological Survey offices BGS Central Enquiries Desk Tel 0115 936 3143 email enquiries Qbgs ac uk Fax 0115 936 3276 Kingsley Dunham Centre Keyworth Nottingham NG12 5GG Tel 0115 936 3241 Fax 0115 936 3488 email sales bgs ac uk Murchison House West Mains Road Edinburgh EH9 3LA Tel 0131 667 1000 Fax 0131 668 2683 email scotsales bgs ac uk Natural History Museum Cromwell Road London SW7 5BD Tel 020 7589 4090 Fax 020 7584 8270 Tel 020 7942 5344 45 email bgsl
13. he urban environment Part 1 Quality Control Procedures In Johnson Christopher Demetriades Alecos Locutura J Ottesen Rolf Tore eds Mapping the chemical environment of urban areas John Wiley amp Sons Chapter 5 61 76 JOHNSON C C ANDER E L LISTER T R AND FLIGHT D M A 2008 Data conditioning of environmental geochemical data quality control procedures used in the British Geological Survey s regional geochemical mapping project In de Vivo B Belkin H E Lima A eds Environmental geochemistry site characterization data analysis and case histories Amsterdam London Elsevier 93 118 G BASE Project G BASE web site http www gs ac uk gbase JOHNSON C C BREWARD N ANDER E L AND AULT L 2005 G BASE Baseline geochemical mapping of Great Britain and Northern Ireland Geochemistry exploration environment analysis 5 4 347 357 10 1144 1467 7873 05 070 G BASE Urban Geochemical Mapping FLIGHT D M A AND SCHEIB A J 2011 Soil geochemical baselines UK urban centres The G BASE Project In Johnson Christopher Demetriades Alecos Locutura J Ottesen Rolf Tore eds Mapping the chemical environment of urban areas John Wiley amp Sons Chapter 13 186 206 FORDYCE F M BROWN S E ANDER E L RAWLINS B G O DONNELL K E LISTER T R BREWARD N AND JOHNSON C C 2005 GSUE urban geochemical mapping in Great Britain Geochemistry Exploration Env
14. ironment Analysis 5 4 325 336 10 1144 1467 7873 05 069 JOHNSON C C AND ANDER E L 2008 Urban geochemical mapping studies how and why we do them Environmental Geochemistry and Health 30 6 511 530 10 1007 s10653 008 9 189 2 12
15. ndicate within site and within sample variability respectively Using a statistical technique called nested ANOVA Analysis of Variance the duplicates can be used to give an estimate of the between site variability for each element A variability that represents gt 80wt of between 9 OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 site total variance shows that the sampling and analytical methodology are satisfactory though ANOVA analysis is not valid when a large number of samples have element concentrations that are near or below detection If there is a high percentage of variance within site then the results suggest that the element concerned shows a high variability in the soil over short distances A high within sample variance indicates a high degree of uncertainty in the analytical determination for the element concerned Results for the ANOVA analysis of the London Earth soil duplicates and replicates are given in Table 5 This shows the poor between site variance for Yb Hg Sm and Ta suggesting that any interpretation of these elements should be done with caution Element Between Site wt Between Sample wt Number of sites Element Between Site wt Between Sample wt Number of sites Table 5 A table showing the nested ANOVA results for the London Earth soil duplicate and replicate sets The
16. ondon G bgs ac uk Columbus House Greenmeadow Springs Tongwynlais Cardiff CF15 7NE Tel 029 2052 1962 Fax 029 2052 1963 Maclean Building Crowmarsh Gifford Wallingford 10 8BB Tel 01491 838800 Fax 01491 692345 Geological Survey of Northern Ireland Colby House Stranmillis Court Belfast BT9 5BF Tel 028 9038 8462 Fax 028 9038 8461 www bgs ac uk gsni Parent Body Natural Environment Research Council Polaris House North Star Avenue Swindon SN2 1EU Tel 01793 411500 Fax 01793 411501 www nerc ac uk Website www bgs ac uk Shop online at www geologyshop com OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 Foreword This report presents a description of the BGS London Earth Topsoil Chemical survey The purpose of this user guide is to enable those licensing this dataset to have a better appreciation of how the data set has been created and therefore better understand the potential applications and limitations that the dataset may have Acknowledgements A number of individuals in the Land Use Planning and Development Programmes have contributed to the project and helped compile this report This assistance has been received at all stages of the study In addition to the collection and processing of data many individuals have freely given their advice and provided local knowledge Contents co oed Ca
17. or incorporate the data in the generation of products or services for commercial purposes e sell assign sublicense rent lend or otherwise transfer any part of the dataset s or the licence place any part of the dataset s on the Internet The BGS is committed to ensuring that all the digital data it holds which is released to external parties under licence has been through a robust internal approval process to ensure that geoscientific standards and corporate quality assurance standards are maintained This approval process is intended to ensure that all data released 1 is quality assured ii meets agreed BGS data management standards iii is not in breach of any 3rd party intellectual property rights or other contractual issues such as confidentiality issues that would mean that release of the data is not appropriate When the BGS digital datasets are revised any upgrades will be automatically supplied to the licensee at no additional cost Geological map datasets are revised on a periodic rather than on an annual basis licensees will therefore not automatically receive a new dataset each year unless changes have been made to the data These are general comments for guidance only A licensee of BGS s digital data is provided with full details of the basis on which individual BGS datasets licensed to them are supplied If you have any doubts about whether your proposed use of the BGS data will be covered by a BGS digital li
18. sx created 18 May 2011 This guide describes and explains the London Earth topsoil chemical results The London Earth project is part of a nationwide project to determine the distribution of chemical elements in the surface environment namely the Geochemical Baseline Survey of the Environment G BASE London Earth focuses on the soil of the capital city the limits of the survey being defined by the Greater London Authority GLA administrative boundary Figure 1 Chemical elements have been determined by X ray fluorescence spectrometry XRFS at the laboratories of the British Geological Survey BGS in Keyworth Nottingham These results are presented as a MS Excel file OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 2 rer EA mdi i uid NM x HORS Re pru d eee ha PED D 2 LEE sie e Figure 1 A plot of the London Earth topsoil sites in file LondonEarth Topsoil XRFS v1 xlsx within a polygon of the GLA 21 SAMPLE COLLECTION Soil samples were collected at a density of four samples from every square kilometre Each sample is a composite of five subsamples collected at the corners and centre of a 20 m square The soil was collected using a 1 m stainless steel hand held soil auger and stored in Kraft paper bags The topsoil was collected from a standard depth in the soil profile 5 20 cm A surface soil 0 2 cm and deep soil 35 50 cm were also collecte
19. t included in the results provided in the Excel data file which this user guide describes A summary of primary reference materials analysed along with London Earth soil samples is given in Table 4 These are certified reference materials CRM for which there is an accepted set of results and can be used to assess the accuracy of the element results Table 4 shows tabulated certified values versus data values reported by the BGS XRF laboratory for four accredited reference materials GSD 7 GSS 1 LKSD 1 LKSD 4 Certified data values are indicated in red and represent a mean value derived from approximately 20 analyses of each material The precision of the results is demonstrated by repeatedly analysing a secondary reference material and an example is given in Figure 2 OR 11 035 Final 1 0 Project Code Last modified 2011 05 27 08 23 Site Number Date 02 08 2005 13 11 2009 Easting 503724 561819 Northing 155662 200757 Ag 4 809181 0 1 200 9 Cd 3 218913 0 165 2 Sn 43 43841 0 9 1041 5 Sb 12 8729 0 1 434 6 I 3 008918 0 1 64 8 Cs 1 311103 1 11 147 9445 143 5 3475 1 8 75202 3 130 12 88859 18 238 0 444684 3 33 3 432534 52 77 0 150692 1 179 0 042119 0 697 1 229329 15 37 377 93 10000 3 22153 33 3 28 56777 302 3
20. these elements are below the lower limit of detection Loss on ignition LOI an indicator of the soil s organic content and pH has also been determined this is available as separate MS Excel spreadsheet LondonEarth Topsoil pHLOI vl in which there are 6 467 sample results The loss on ignition is determined by weighting samples before and after heating the soil sample at 450 C for 24 hrs The soil pH is determined using a pH meter on a slurry of the sample made using 0 01 M CaCl 2 5 RESULTS When the results are received from the laboratory they undergo a series of data conditioning processes to check the quality of the data and to level the results so the will fit seamlessly with other UK soil chemical results when plotted as maps This data conditioning is described below and uses control samples submitted with the analytical batches and are seen as normal samples by the analyst Once the data has been conditioning it is loaded to the BGS Oracle Geochemical Database a repository for all the BGS UK landmass surface chemical results In the Geochemistry Database every element result is qualified with a qualifier code that identifies any data quality issues relating to that result Most results have no qualifier code 4 OR 11 035 Final 1 0 Last modified 2011 05 27 08 23 indicating there are no data quality issues Results with qualifiers are those generally with results that are below the element s detection limit Qualified dat
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