Soil metal/metalloid concentrations in the Clyde Basin, Scotland, UK: implications for land quality

Abstract

An assessment of topsoil (5–20cm) metal/metalloid (hereafter referred to as metal) concentrations across Glasgow and the Clyde Basin reveals that copper, molybdenum, nickel, lead, antimony and zinc show the greatest enrichment in urban versus rural topsoil (elevated 1.7–2.1 times; based on median values). This is a typical indicator suite of urban pollution also found in other cities. Similarly, arsenic, cadmium and lead are elevated 3.2–4.3 times the rural background concentrations in topsoil from the former Leadhills mining area. Moorlands show typical organic-soil geochemical signatures, with significantly lower (P<0.05) concentrations of geogenic elements such as chromium, copper, nickel, molybdenum and zinc, but higher levels of cadmium, lead and selenium than most other land uses due to atmospheric deposition/trapping of these substances in peat. In farmland, 14% of nickel and 7% of zinc in topsoil samples exceed agricultural maximum admissible concentrations, and may be sensitive to sewage-sludge application. Conversely, 5% of copper, 17% of selenium and 96% of pH in farmland topsoil samples are below recommended agricultural production thresholds. Significant proportions of topsoil samples exceed the most precautionary (residential/allotment) human-exposure soil guidelines for chromium (18% urban; 10% rural), lead (76% urban; 45% rural) and vanadium (87% urban; 56% rural). For chromium, this reflects volcanic bedrock and the history of chromite ore processing in the region. However, very few soil types are likely to exceed new chromiumVI-based guidelines. The number of topsoil samples exceeding the guidelines for lead and vanadium highlight the need for further investigations and evidence to improve human soil-exposure risk assessments to better inform land contamination policy and regeneration.

Assessing threats to shallow groundwater quality from soil pollutants in Glasgow, UK: development of a new screening tool

“…Input datasets 1.2.1. Soil properties Information on soil properties for GRASP is taken from the BGS Geochemical Baseline Survey of the Environment (G-BASE) soil geochemistry dataset for Glasgow (Fordyce et al 2012(Fordyce et al , 2018. This dataset comprises 1381 urban soil samples collected at a density of 1 per 0.25km2 (on a 500-m grid) and 241 peri-urban samples at a density of 1 per 2km2 across the Glasgow conurbation ( Fig.…”

“…On the other hand, Cr and Ni concentrations in Johnstone are also influenced by the presence of artificial ground and urban pollution. Similarly, a marked cluster of high metal rankings is evident in the Rutherglen area, associated with the former metalworking heartland of the East End, including the world's largest chrome-producing works, which was active during the 19th Century (Fordyce et al 2012(Fordyce et al , 2018. High soil concentrations of these metals are also associated with the ship building corridor along the River Clyde.…”

“…Comparisons between borehole groundwater chemistry and soil chemistry were carried out using the 'spatial join' function in ArcGIS to link each borehole location to interpolated surface maps of the soil geochemistry data to estimate the soil metal concentration at each borehole site. The interpolated geochemical maps are described in Fordyce et al (2018). The distributions of metal concentration in groundwater and soil were positively skewed; hence, the data were log transformed prior to statistical analysis.…”

The Geoscience Context for Europe's Urban Sustainability – Lessons from Glasgow and Beyond (CUSP): preface

“…The influence of Glasgow's urban and industrial history on environmental quality are explored further in systematic assessments of soil and stream water geochemistry carried out across the conurbation and wider River Clyde Basin. The soil paper by Fordyce et al (2018b) reveals that metal concentrations in the urban environment (especially copper, molybdenum, nickel, lead, antimony, zinc and chromium) are typically up to 2.1 times (median values) those of rural soil, as a consequence of urbanisation. The bioaccessibility and mobility of arsenic, chromium and lead in Glasgow soil are evaluated further in the paper by Wragg et al (2018).…”

Soil metal/metalloid concentrations in the Clyde Basin, Scotland, UK: implications for land quality – CORRIGENDUM

“…In the above article (Fordyce, F., Everett, P., Bearcock, J., & Lister, T. (2019)), Figure 7 was not published in its entirety. The correct figure should be as follows:…”