The revised Environmental Protection Act Part 2A contaminated land Statutory Guidance (England and Wales) makes reference to 'normal' levels of contaminants in soil. The British Geological Survey has been commissioned by the United Kingdom Department for Environment, Food and Rural Affairs (Defra) to estimate contaminant levels in soil and to define what is meant by 'normal' for English soil. The Guidance states that 'normal' levels of contaminants are typical and widespread and arise from a combination of both natural and diffuse pollution contributions. Available systematically collected soil data sets for England are explored for inorganic contaminants (As, Cd, Cu, Hg, Ni and Pb) and benzo[a]pyrene (BaP). Spatial variability of contaminants is studied in the context of the underlying parent material, metalliferous mineralisation and associated mining activities, and the built (urban) environment, the latter being indicative of human activities such as industry and transportation. The most significant areas of elevated contaminant concentrations are identified as contaminant domains. Therefore, rather than estimating a single national contaminant range of concentrations, we assign an upper threshold value to contaminant domains. Our representation of this threshold is a Normal Background Concentration (NBC) defined as the upper 95% confidence limit of the 95th percentile for the soil results associated with a particular domain. Concentrations of a contaminant are considered to be typical and widespread for the identified contaminant domain up to (and including) the calculated NBC. A robust statistical methodology for determining NBCs is presented using inspection of data distribution plots and skewness testing, followed by an appropriate data transformation in order to reduce the effects of point source contamination.

Jurassic ironstones outcropping over parts of eastern England give rise to soils with arsenic concentrations in excess of the UK soil guideline value of 20 mg kg(-1) for residential areas. Total arsenic concentrations were determined for 73 ironstone derived soils and bioaccessible arsenic determined using an in vitro physiologically based extraction test. The bioaccessible arsenic concentration for these soils was found to be well below the soil guideline value with a mean concentration of 4 mg kg(-1) and a range of 2-17 mg kg(-1). The bioaccessible fraction ranges from 1.2 to 33%. Data from a sequential extraction test based on the use of aqua regia as the main extractant is presented for a subset of 20 of the soils. Chemometric data reduction is used to demonstrate that the bioaccessible arsenic is mainly contained within calcium iron carbonate (sideritic) assemblages and only partially iron aluminosilicates, probably berthierine, and iron oxyhydroxide phases, probably goethite. It is suggested that the bulk of the non-bioaccessible arsenic is bound up with less reactive iron oxide phases.

Impact of the earthwormHuman activities have resulted in an increase in the concentrations of metals and 37 metalloids in urban and rural soils due to diffuse and point source pollution. These 38 disruptions to the natural biogeochemical cycle of metals and metalloids can lead to 39 toxic effects on flora and fauna. Earthworms are found in soils containing elevated 40 levels of metals and metalloids (Spurgeon and Hopkin, 1996; Langdon et al., 2001; 41 Vijver et al., 2007) and represent a major constituent of soil fauna. Bioavailable-rather 42 than total-concentrations determine metal toxicity in soils (Harmsen, 2007) and this is 43 dependent on mobility and speciation in the living soil environment (Di Toro et al., 44 2001; Thakali et al., 2006; Arnold et al., 2007). In order to assess properly the risks that Generally earthworms increase the mobility and availability of metals and metalloids in 50 soils (Sizmur and Hodson, 2009). This can result in greater concentrations of metals 51 leaching out of the soil into ground water (Tomlin et al., 1993) or greater uptake into 52 plants (Ma et al., 2003; Yu et al., 2005; Wang et al., 2006) and soil animals (Currie et 53 al., 2005; Coeurdassier et al., 2007). In addition to this, earthworms may reduce the 54 efficiency of soil remediation by mobilising recalcitrant metals (Udovic et al., 2007). 55The mechanisms for earthworms increasing metal mobility and availability are unclear, 56 but may involve changes in microbial populations, pH, dissolved organic carbon or 57 metal speciation (Sizmur and Hodson, 2009 BS7755-3.9, 1995) and cation exchange capacity was measured at 93 pH 7 using the ammonium acetate method (Rowell, 1994). Pore water was extracted from moist bulk soil from each pooled sample by centrifuging 128 at 6000rpm for 60 min. This extracted 51 % (SD = 0.9, n = 2), 56% (SD = 3.3, n = 2) 129 and 65% (SD = 0.7, n = 2) of the soil moisture from the Rookhope, Wisley and DGC 130 soils respectively. Pore water samples were analysed for pH (Jenway 3310 pH meter), 131 7 elements (ICP-OES), major anions (Dionex DX-500 ion chromatograph), and Total 132Organic Carbon (TOC) (Shimadzu TOC 5000). Speciation of Cu, Pb and Zn in pore 133 water samples was modelled using WHAM VI (Tipping, 1998). In the absence of 134 characterisation of the TOC fractions, we assumed that 50% of TOC was fulvic in 135 origin and that the fulvic acid contained 50% C (Tipping, 1996; Pribyl, 2010). 137Arsenic speciation in pore waters extracted from the DGC soil was determined in a 138 separate experiment. This was carried out at the Analytical Geochemistry Laboratory at 139British Geological Survey, Keyworth separately to the previous experiment to ensure 140 that freshly produced pore waters were analysed within 24 hours of extraction. 166Recoveries of these elements were 103%, SD = 2.4, n = 2 for Cu, 93%, SD = 4.2, n = 2 167 for Pb and 90%, SD = 0.81, n = 2 for Zn. Arsenic was below detection limits in the in- Results 173Earthworm mortality was low in the contaminated ...

This study characterises the total As concentrations and As bioaccessibility in 109 soils from Devon Great Consols Mine, an abandoned Cu-As mine in Devon, SW England, UK and discusses the soil and mineralogical factors that influence the bioaccessibility of this element. These data provide the basis for developing more accurate exposure estimates for use in human health risk assessments. The median value of the percent bioaccesible As of 15 % for these As rich soils contaminated by mining activities indicated that relatively little of the total As is present in a bioaccessible form. Spatial variability of As bioaccesibility in the soils was also recognised throughout the mine site as a function of mineralogy. Multivariate statistical analysis identified a sulphide component responsible for the reduced As bioaccessibility of one cluster of soils. In the larger cluster of acidic mine soils covered by woodland As is mainly hosted in Fe oxyhydroxides whose partial ______________________ *Address Correspondence to Barbara Palumbo-Roe, British Geological Survey, Keyworth, Nottingham, NG12 5GG, U.K, Tel: 44+115+9363542, Fax:44+115+9363261, e-mail: bpal@bgs.ac.uk 2 dissolution is responsible for the bioaccessible As fraction. It was highlighted that the degree of Fe oxyhydroxide crystallinity might represent an important factor influencing arsenic bioaccessibility. Mine soils from Devon Great Consols Mine showed overall higher As bioaccessibility (15 %) than other mineralised soils not affected by mining activities and background soils within the Tamar Catchment whose percent bioaccessible As median values were 9 %.

As, Cu, Pb and Zn, respectively, for up to 112 days, in parallel with earthworm-free 29 columns. Leachate was produced by pouring water on the soil surface to saturate the 30 soil and generate downflow. Ryegrass was grown on the top of columns to assess 31 metal uptake into biota. Different ecological groups affected metals in the same way 32 by increasing concentrations and free ion activities in leachate, but anecic L. terrestris 33 had the greatest effect by increasing leachate concentrations of As by 267%, Cu by 34 393%, Pb by 190%, and Zn by 429% compared to earthworm-free columns. Ryegrass 35 grown in earthworm-bearing soil accumulated more metal and the soil microbial 36 community exhibited greater stress. Results are consistent with earthworm enhanced 37 degradation of organic matter leading to release of organically bound elements. The 38 degradation of organic matter also releases organic acids which decrease the soil pH. 39The earthworms do not appear to carry out a unique process, but increase the rate of a 40 process that is already occurring. The impact of earthworms on metal mobility and 41 availability should therefore be considered when inoculating earthworms into 42 contaminated soils as new pathways to receptors may be created or the flow of metals 43 and metalloids to receptors may be elevated. 44

This paper examines Pb concentrations and sources in soil, grass and heather from the Rookhope catchment in the North Pennines, UK, an area of historical Pb and Zn mining and smelting. Currently, the area has extensive livestock and sports shooting industries. Risk assessment, using the source-pathway-receptor paradigm, requires the quantification of source terms and an understanding of the many factors determining the concentration of Pb in plants. A paired soil and vegetation (grass and heather) geochemical survey was undertaken. Results showed no direct correlation between soil (total or EDTA extractable Pb) and vegetation Pb concentration. However, regression modelling based on the Free-Ion Activity Model (FIAM) suggested that the underlying mechanism determining grass Pb concentration across the catchment was largely through root uptake. Spatial patterns of (206/207)Pb isotopes suggested greater aerosol deposition of Pb on high moorland and prevailing wind facing slopes. This was evident in the isotopic ratios of the heather plants. Pb isotope analysis showed that new growth heather tips typically had (206/207)Pb values of ~1.14, whilst grass shoots typically had values ~1.16 and bulk soil and peat ~1.18. However, the (206/207)Pb ratio in the top few cm of peat was ~1.16 suggesting that grass was accessing Pb from a historical/recent pool of Pb in soil/peat profiles and consisting of both Pennine ore Pb and long-range Pb deposition. Isotope Dilution assays on the peat showed a lability of between 40 and 60%. A simple source apportionment model applied to samples where the isotope ratios was not within the range of the local Pennine Pb, suggested that grass samples contained up to 31% of non-Pennine Pb. This suggests that the historical/recent reservoir of non-Pennine Pb accessed by roots continues to be a persistent contaminant source despite the principal petrol Pb source being phased out over a decade ago.

18Purpose Past metal mining has left a legacy of highly contaminated sediments representing a significant diffuse 19 source of contamination to water bodies in the UK and worldwide. This paper presents the results of an 20 integrated approach used to define the role of sediments in contributing to the dissolved lead (Pb) loading to 21 surface water in a mining-impacted catchment. 22Materials and methods The Rookhope Burn catchment, northern England, UK, is affected by historical mining 23 and processing of lead ore. Quantitative geochemical loading determinations, measurements of interstitial water 24 chemistry from the stream hyporheic zone, and inundation tests of bank sediments were carried out. 25Results and discussion High concentrations of Pb in the sediments from the catchment, identified from the

One of the global legacies of industrialisation is the environmental impacts of historic mineral exploitation. Recent national initiatives to manage the impacts on ground and surface waters have driven the need to develop better techniques for assessing understanding of the catchment-scale distribution and characterisation of the relative contribution of point and diffuse contaminant sources. The benefits of a detailed, multidisciplinary investigation are highlighted through a case study focused on the Rookhope Burn, a tributary of the River Wear, which falls within a significantly mine impacted area of the North Pennines Orefield, UK. Zinc (Zn) has been identified as the contaminant of concern within this catchment, which is judged by the Environment Agency to be at risk of failing to achieve good water quality status in the context of the Water Framework Directive. The results of synoptic flow monitoring and sampling for chemical determinations of major and trace elements have been used to calculate mass balances of instream and inflow chemical loads in the Rookhope Burn. Despite a dominant impact on the water quality from a mine outburst