Chemical elements in our environment

Humans are intimately linked to the Earth’s surface environment; we are fundamentally dependent on it, yet we are responsible for many aspects of environmental change. This provides an urgent impetus to enhance our knowledge of the chemical status of our environment and improve our understanding of the processes and consequences of environmental change so that any hazards can be identified. The BGS delivers our National Capability in baseline geochemical mapping, providing a flexible observational framework for the chemistry of Britain’s surface environment

High resolution observations of 137Cs in northern Britain and Ireland from airborne radiometric data

This study presents high-resolution airborne geophysical estimates of the distribution of 137Cs across three areas of northern Britain and Ireland. The radiometric spectra were acquired as part of a program of modern resource and environmental surveying. The largest survey area considered covers the whole of Northern Ireland. All three data sets display some clustering on high ground together with regional scale banding features. The two main banding directions are approximately NNW-SSE and NW-SE. Our interpretation of the regional scale features is in relation to existing knowledge of the wet deposition model of the Chernobyl release of 1986. The airborne estimates, obtained at 200 m flight line intervals, add significant detail in relation to the meteorological and atmospheric interactions involved in the fallout from the Chernobyl plume over Western Europe

London Earth : anthropogenic and geological controls on the soil chemistry of the UK’s largest city

The soil geochemical survey of the Greater London (UK) area, comprising over 6400 sample sites, is the most detailed and comprehensive urban mapping project carried out to date. In order to give insight into the environmental impacts of urbanisation and industrialisation, as well as to characterise the geochemical baseline of the UK’s most populous city, samples were collected at a density of 4 sites per km2. The <2 mm fraction from the topsoil samples (5 – 20 cm) was analysed by X-ray fluorescence spectrometry (XRFS). Resulting data for over 50 elements were subject to rigorous quality control procedures to ensure accurate and inter-comparable data. Anthropogenic modification to soil baseline concentrations is evident across the urban area. A notable feature is the ‘central zone’ of higher concentrations of, for example, Pb, Sb, Ca, Zn, Cu, Sn and As in the oldest, most intensely urbanised parts of the city. In the cases of Pb and Sb in particular, high-density traffic is a likely source. Local ‘hotspots’ of elevated concentrations, related to particular anthropogenic activities, can also be identified. For example Se, Cd, Ni, Cu and Zn show particularly elevated concentrations in the vicinity of an industrial area on the banks of the river Lee in north London, whilst Cr and Cd also display high concentrations around Heathrow airport in the west. Despite these anthropogenic controls, a strong geological control on soil chemistry is observed for many elements. This is particularly evident in south London where high baseline concentrations of, for example, Ca, Ce, I, La, Mn, Nd, P, Sr, Y and Zr, relate to the influence of the Cretaceous chalk bedrock. In the north-western quadrant of London and along the northern boundary of the project area, high baseline concentrations for a number of elements (Al, Fe, Mg, K, Cr, La, Ti, Ga, Rb and Ni) are associated with the outcrop of Palaeogene clays. Elevated levels of Hf and Zr correspond to areas of Eocene marine and Quaternary wind-blown deposits. One of the most interesting features of the mapped data is the consistently low concentrations of metals associated with the Royal Parks (Bushy and Richmond), Hampton Court and nearby Wimbledon Common in southwest London, which contrast with surrounding areas. Throughout the urban evolution of London these parks have avoided significant residential or industrial activity and remain free of imported soil, wastes or ‘made ground’. Consequently, comparison of geochemical baselines within and outside the parks, where underlying geology is consistent, can help to provide an indication of ambient anthropogenic geochemical modification of London’s soils

High spatial resolution observations of 137Cs in northern Britain and Ireland from airborne geophysical survey

This study reports the 137Cs data derived from three regional and national scale High Resolution Airborne Resource and Environmental Surveys (HiRES) in northern Britain and Ireland. The detailed spatial resolution, combined with the large areas these surveys collectively cover, gives insight into large-scale deposition patterns and possible subsequent re-distribution of 137Cs on a level that was previously not possible. The largest survey area considered covers the whole of Northern Ireland. All three data sets display some clustering of higher 137Cs activities on high ground together with regional scale NNW-SSE and NW-SE banding features. We interpret these as representing a series of rainfall interceptions of the repeated passage of the Chernobyl plume. Our observations, obtained at 200 m flight line intervals, appear to provide significant detail in relation to existing knowledge of large scale along-wind deposition of 137Cs

Airborne uranium data in support of radon potential mapping in Derbyshire, Central England

In order to assess if uranium (eU) data gathered by airborne survey could support the radon potential mapping process in areas with few indoor radon measurements, the relationship between airborne eU values, ground-based eU measured by in situ gamma spectrometry, indoor radon and soil gas radon was investigated for Derbyshire, Central Britain. Significant correlations between the airborne eU geometric mean and the geometric mean of indoor radon for a single geological unit can be demonstrated in some urban areas (e.g. Buxton, Derbyshire, England) where there are many indoor radon measurements. Significant correlation was also shown in the Buxton area between airborne eU data, soil gas radon measurements and the percentage of houses estimated to exceed the UK Action Level of 200 Bq m-3. At the regional scale, airborne eU data correlates significantly (p=0.0005) with geometric mean indoor radon for data grouped by generalised geology and 1-km grid square when data for all geologies are considered together. Significant correlations for individual geological units are found only when these include a wide range of eU and indoor radon values (e.g. Visean Limestone). Permeability of the parent material (soil, superficial deposits and/or bedrock) is an important controlling factor in the relationship between eU and indoor radon as the same level of uranium generally gives rise to higher indoor radon when the bedrock is permeable and lower indoor radon when the bedrock is impermeable. Linear regression modelled estimates of indoor radon with K, eTh, eU and permeability as independent predictor variables correlate better with measured indoor radon than when eU is the sole predictor variable

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