{"id":3828,"date":"2025-08-04T15:20:42","date_gmt":"2025-08-04T14:20:42","guid":{"rendered":"https:\/\/www.bgs.ac.uk\/groundwater\/?page_id=3828"},"modified":"2026-04-01T14:48:40","modified_gmt":"2026-04-01T13:48:40","slug":"uk-baseline-sampling-and-analysis","status":"publish","type":"page","link":"https:\/\/www.bgs.ac.uk\/groundwater\/quality\/baseline-chemistry-uk-aquifers\/uk-baseline-sampling-and-analysis\/","title":{"rendered":"UK baseline sampling and analysis"},"content":{"rendered":"\t\t\t<section class=\"hero-section hero-section-with-social\">\n\t\t\t\t\t\t\t\t<div class=\"hero-info-wrap\">\n\t\t\t\t\t<div class=\"container\">\n\t\t\t\t\t\t<div class=\"row\">\n\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t<div class=\"hero-info\">\n\t\t\t\t\t\t\t\t\t<h1>UK baseline sampling and analysis<\/h1>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n\t\t\t<div class=\"social-wrap social-wrap-inline-them\">\n\t\t\t\t<div class=\"sea-background-f\">\n\t\t\t\t\t<span>Share this article<\/span><a target=\"_blank\"  href=\"https:\/\/www.facebook.com\/sharer\/sharer.php?u=https:\/\/www.bgs.ac.uk\/groundwater\/quality\/baseline-chemistry-uk-aquifers\/uk-baseline-sampling-and-analysis\/\"><span class=\"icon-facebook\"><span class=\"hidden\">Facebook<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/twitter.com\/intent\/tweet?text=UK%20baseline%20sampling%20and%20analysis&#038;url=https:\/\/www.bgs.ac.uk\/groundwater\/quality\/baseline-chemistry-uk-aquifers\/uk-baseline-sampling-and-analysis\/\"><span class=\"icon-twitter\"><span class=\"hidden\">Twitter<\/span><\/span><\/a><a   onclick=\"javascript:void( (function() {var e=document.createElement('script' );e.setAttribute('type','text\/javascript' );e.setAttribute('charset','UTF-8' );e.setAttribute('src','\/\/assets.pinterest.com\/js\/pinmarklet.js?r='+Math.random()*99999999);document.body.appendChild(e)})());\"  href=\"javascript:void(0);\"><span class=\"icon-pinterest\"><span class=\"hidden\">Pinterest<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/wa.me?text=https:\/\/www.bgs.ac.uk\/groundwater\/quality\/baseline-chemistry-uk-aquifers\/uk-baseline-sampling-and-analysis\/\"><span class=\"icon-whatsapp\"><span class=\"hidden\">WhatsApp<\/span><\/span><\/a><a   href=\"mailto:?subject=UK%20baseline%20sampling%20and%20analysis&#038;body=%20(https:\/\/www.bgs.ac.uk\/groundwater\/quality\/baseline-chemistry-uk-aquifers\/uk-baseline-sampling-and-analysis\/)\"><span class=\"icon-mail\"><span class=\"hidden\">Email<\/span><\/span><\/a><a href=\"#\" data-copy=\"https:\/\/www.bgs.ac.uk\/groundwater\/quality\/baseline-chemistry-uk-aquifers\/uk-baseline-sampling-and-analysis\/\" class=\"copy-url-on-click\"><span class=\"icon-link\"><span class=\"hidden\">Copy Link<\/span><\/span><\/a><\/div><\/div>\t\t\t\t\t\t\t<\/section>\n\t\t\t\n\n\n<section class=\"wp-block-bgs-blocks-content-container content-section\"><div class=\"container\"><div class=\"row\"><div class=\"col-12\">\n<p>The sites selected for baseline sampling surveys were chosen to ensure that:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>a suitable number of samples from the studied aquifer types were collected, according to the aquifers&#8217; distribution and extent<\/li>\n\n\n\n<li>the samples were distributed as evenly as possible over the aquifer study areas<\/li>\n\n\n\n<li>samples were reasonably representative of groundwater in the studied aquifers<\/li>\n<\/ul>\n\n\n\n<p>We assessed each of the sample sites at the time of sampling, in particular the source construction and the surrounding land use, to identify any potential sources of contamination that could affect the chemistry of sampled groundwater and the risk of contamination. <\/p>\n\n\n\n<p>We did not take samples from boreholes or other groundwater sources that: <\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>might have had contributions of water from intervals other than our target aquifer<\/li>\n\n\n\n<li>were close to obvious sources of contamination<\/li>\n\n\n\n<li>contained storage tanks or treatment systems before the sampling point<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Sample sources<\/h2>\n\n\n\n<p>Samples were taken from boreholes, springs and wells (depending on site accessibility). Shallow, large-diameter wells are least favourable for sampling because of the potential for contamination and difficulties in purging. Wells were only sampled where they were in daily use and the samples obtained likely to be representative.<\/p>\n\n\n<figure  class=\"img-wrap\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/groundwater\/wp-content\/uploads\/sites\/4\/2025\/08\/LincsLimestone.jpg\" class=\"lazy-blur\" alt=\"Water spurts from a borehole set in a rectangular concrete hole in some grass. rectangular\" data-src=\"https:\/\/www.bgs.ac.uk\/groundwater\/wp-content\/uploads\/sites\/4\/2025\/08\/LincsLimestone.jpg\" \/><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/groundwater\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Groundwater from the <a href=\"https:\/\/webapps.bgs.ac.uk\/lexicon\/lexicon.cfm?pub=LL\">Lincolnshire Limestone Formation<\/a>. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<p>Springs and wells typically tap shallow groundwater and have relatively small catchments, so they are less likely than boreholes to represent a mixture of groundwaters from different depths. Springs are constantly flowing and, as such, are naturally purged. Sampled spring groundwater is therefore likely to be representative of groundwater in the surrounding aquifer.<\/p>\n\n\n\n<p>Sources were pumped before sampling wherever possible, in order to purge standing water and obtain a sample representative of aquifer conditions.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Sampling and analysis protocol<\/h2>\n\n\n\n<p>During sample collection, we made field measurements of:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>groundwater pH<\/li>\n\n\n\n<li>dissolved oxygen (DO)<\/li>\n\n\n\n<li>redox potential (Eh)<\/li>\n\n\n\n<li>alkalinity<\/li>\n\n\n\n<li>temperature<\/li>\n\n\n\n<li>specific electrical conductance (SEC)<\/li>\n<\/ul>\n\n\n\n<p>Where possible, DO, pH and Eh were measured in an in-line flow cell to minimise atmospheric contamination.<\/p>\n\n\n<figure  class=\"img-wrap\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/groundwater\/wp-content\/uploads\/sites\/4\/2025\/08\/MidlandValley.jpg\" class=\"lazy-blur\" alt=\"A white woman wearing a yellow hard hat, a blue jacket and a yellow hi-vis vest pours water into a bottle. She is crouched down and surrounded by buckets and sampling equipment.\" data-src=\"https:\/\/www.bgs.ac.uk\/groundwater\/wp-content\/uploads\/sites\/4\/2025\/08\/MidlandValley.jpg\" \/><figcaption class=\"caption sm-line\">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/groundwater\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Field chemistry in the Midland Valley of Scotland. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<p>Samples for subsequent laboratory analysis were filtered through or 0.2&nbsp;\u03bcm or 0.45&nbsp;\u03bcm filters and collected in polyethylene bottles rinsed with sample water before collection. Two filtered aliquots were collected at each site, one acidified to 1&nbsp;per cent v\/v with Aristar HNO<sub>3<\/sub> for analysis of major cations, SO<sub>4<\/sub> and trace elements by inductively coupled plasma mass spectrometry (ICP-MS), and the other left unacidifed for the analysis of anions by ion chromatography.<\/p>\n\n\n\n<p>Samples were also collected in chromic-acid-washed glass bottles for DOC analysis, after filtration using 0.45&nbsp;\u03bcm, silver-impregnated filters. DOC was measured by carbon analyser. At a selection of sample sites, additional water samples were collected in glass bottles for stable isotopic analysis. At some sites, samples were also collected in glass bottles for CFC and SF<sub>6<\/sub>&nbsp;analysis.<\/p>\n\n\n\n<p>Analysis was carried out at the&nbsp;<a href=\"https:\/\/www.bgs.ac.uk\/geological-research\/science-facilities\/\">BGS laboratories<\/a>&nbsp;in BGS Keyworth and the former BGS site at Wallingford. The Keyworth laboratory has well-established QA procedures and holds ISO 17025:2005 certification (UKAS Testing Laboratory 1816) for analysis of aqueous samples, as well as a wide range of geological materials. Specialist CFC and SF<sub>6<\/sub>&nbsp;analytical facilities were housed in the Wallingford laboratory.<\/p>\n<\/div><\/div><\/div><\/section>\n\n\n<section class=\"cta-section  sea-background-e \">\n\t<div class=\"container\">\n\t\t<div class=\"row md-row\">\n\t\t\t<div class=\"col-12\">\n\t\t\t\t<h2>Need more information?<\/h2>\t\t\t\t\t\t\t\t<div class=\"btn-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/people\/lapworth-daniel\/\"  class=\"button primary-background   \">Contact Dan Lapworth<\/a><\/div>\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n<\/section>\n\t","protected":false},"excerpt":{"rendered":"","protected":false},"author":7,"featured_media":0,"parent":1995,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"1","_relevanssi_noindex_reason":"","footnotes":""},"tags":[],"class_list":["post-3828","page","type-page","status-publish","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.2 - 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