Quantifying heavy metal inputs to agricultural soils in England and Wales

Heavy metal inputs to agricultural soils in England and Wales were estimated from major sources, including atmospheric deposition, biosolids, livestock manures, inorganic fertilisers and lime, industrial by‐product ‘wastes’ and composts (year 2000). Across the whole agricultural land area, atmospheric deposition was the main source of most metals ranging from 25 to 85% of total inputs. Livestock manures and biosolids were also important sources representing 37 and 8% of total zinc (Zn) inputs, 40 and 17% for copper (Cu), and 10 and 4% for cadmium, respectively. The highest heavy metal input rates on a field basis were generally from biosolids, although Zn and Cu inputs from pig manures were equivalent to 46–52% of biosolids inputs (both applied at a rate of 250 kg/ha total N). The study provided baseline information to develop and focus policies limiting heavy metal inputs to and accumulation in topsoils.     

Arsenic and heavy metals in soils associated with regional geochemical anomalies in South-West England

Regional geochemical maps have shown extensive anomalies of arsenic, copper and other heavy metals in those parts of South-West England associated with mineralised zones around the granite intrusion. Studies in the vicinity of the River Tamar and of the metamorphic aureole around Dartmoor have confirmed significantly higher concentrations of arsenic and heavy metals in soils contaminated by mining, smelting and mineralisation compared with those from nearby control areas. Arsenic and copper show the greatest degree of enhancement ranging up to 900 ppm As and 2000 ppm Cu in both alluvial and upland topsoils within the Tamar area. Preliminary analyses indicate that the trace metal content of pasture herbage-reflects in part the degree of soil contamination. Maximum concentrations of 35 ppm As and 22 ppm Cu in autumn sampled herbage were found at contaminated sites compared with mean values of less than 0.5 ppm As and 8 ppm Cu in control areas. Geochemical reconnaissance surveys based on stream sediment sampling provide a useful indication of areas wherein widescale soil contamination may occur.     

Baseline values for heavy metals in agricultural soils in an European Mediterranean region

Baseline values for heavy metals were proposed in Alicante (Spain), a representative agricultural area of the European Mediterranean region, as a basis to identify and assess soil contamination processes at regional level. Fifty-four agricultural plots were sampled and heavy metals concentrations were analysed for nine elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) by atomic absorption spectrometry (AAS) after acid digestion with HNO(3) and HCl in a microwave oven. Heavy metal concentrations obtained in the study area were similar to concentrations analysed by other authors within the European Mediterranean region. However, some agricultural plots with a high heavy metal content were identified by statistical treatment (boxplots) as outliers and, therefore, were not considered for establishing baseline values. Baseline values in Alicante were proposed by taking into account the statistical approach extensively used elsewhere, which refers to the increase in the mean plus twice the standard deviation. The baseline values were: 0.7 mg/kg for Cd, 11 mg/kg for Co, 36 mg/kg for Cr, 28 mg/kg for Cu, 19,822 mg/kg for Fe, 402 mg/kg for Mn, 31 mg/kg for Ni, 28 mg/kg for Pb and 83 mg/kg for Zn. The experience gained in this work further suggests that baseline values for heavy metals should be proposed in other areas. This is necessary to facilitate the identification of soil contamination processes over the whole European Mediterranean region as a basis to undertaking appropriate action to protect soil resource quality.     

Bioavailability of heavy metals from polluted soils to plants

The aim of this work was to estimate, on the basis of soil extraction procedures, whether a given soil is suitable for cultivation of plants used as food or feed. The paper discusses the transfer of metal ions (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn) from contaminated soils to plants in terms of transfer factors (TF). The knowledge of transfer factors for a given element should enable prediction, before plants are sowed, whether a given soil is suitable for the cultivation of plants for consumption purposes. TF can only be evaluated when a linear relationship is observed between soil and plant composition for a given element. Such a relationship is rarely observed between the total soil content of a given metal and that of the plant. For this reason, it was necessary to develop an extraction procedure that would represent the content of metal available to plants during growing season. Several extracting agents were tested. The extracting agent that fulfilled these criteria was 2% (w/v) ammonium citrate. Statistically significant correlation coefficients were determined between the citrate-soluble fraction of soil and content in plant in the case of all the elements studied, except Ni. If a statistically significant correlation exists, it is then possible to evaluate the soil-plant transfer factor for a given metal in plants.     

An Integrated Approach to Flood Forecasting and Warning in England and Wales

Flood-warning systems have been researched and discussed for several decades, and there is a large degree of consensus among researchers that an integrated approach to such systems is the most effective. There is evidence to show that flood-warning systems are rarely operated in an integrated way and, as a consequence, tend to function sub-optimally. The new powers vested in the Environment Agency in 1996, to oversee the total warning process in England and Wales, provide a unique opportunity to develop an integrated approach to flood detection, forecasting, warning dissemination and response, and therefore an improved service to other agencies and communities at risk from flooding.     

Atmospheric accessions of heavy metals to some New Zealand pastoral soils

Total heavy metal deposition was monitored at seven rural sites across New Zealand to determine the rate of atmospheric deposition of heavy metals to soils and to evaluate any regional and temporal variations in metal deposition. Heavy metal deposition was collected monthly in Warren Spring Laboratory type inverted frisbees. The rate of heavy metal deposition followed the order Zn>Cu>Cr>Pb>Ni>Cd. There were no obvious trends with regards to either seasonal or spatial deposition for any of the heavy metals measured. With the exception of Zn, heavy metal deposition in New Zealand was generally lower than rates measured in other countries. This reflects the general lack of high temperature industrial processes from urban-based industrial processes that are an important source of heavy metal aerosols in other industrialised regions worldwide. The inverted frisbee technique used provides a reliable indication of the magnitude of deposition of heavy metals from the atmosphere at a reasonable cost and with manageable logistical effort for a national survey.     

矿区土壤重金属污染现状及对策

介绍了矿区土壤重金属污染的现状、污染特点、污染来源，同时提出了相应的治理对策，指出植物修复是一种有前途的土壤污染治理技术。     

Heavy metals in soils and radish in a mineralised limestone area of Wales,Great Britain

Halkyn Mountain, Clwyd, Wales is a limestone area containing lead and zinc ores which were mined until quite recently. A survey of agricultural soils has revealed extensive contamination by cadmium, lead and zinc and, to a lesser extent, by copper. Gardens in the area are also similarly contaminated and the composition of radish grown in the gardens reflects this metal enrichment. Soil levels for both total and plant-available cadmium and lead are unusually high and some radish samples exceeded the statutory limit for lead in food.     

River-Channel Changes in England and Wales

An investigation of the literature on river-channel changes in the UK reveals that the rate and extent of changes is much higher than was previously thought. In order to assess how widespread these changes are, and whether the rates and types of changes are typical, an historical survey has been carried out of the streams which drain the upland areas of England and Wales. This survey involved the comparison of Ordnance Survey 1:10,560 maps from approximately 1870 and 1950, and revealed that almost 35% of the rivers draining upland England have shown some pattern instability during this period.
Great variety exists both in the types of channel planform changes and their extent: several rivers possess short isolated reaches of change separated by stable sections. This suggests the operation of thresholds of channel stability, and further research aims to identify these in terms of specific factors and conditions.     

Public Attitudes to In-House Water Recycling in England and Wales

This study, which is based on responses from over 300 individuals in England and Wales, explores how a willingness to use a water-recycling system of specific configuration varies against a number of factors which are linked to system design, system scale, system context, and water-conservation behaviour. Findings show that there is broad willingness to accept in-house water recycling provided that public health is not compromised.     

Strengthening and simultaneous neutralization of alumosilicate soils contaminated with heavy metals and petroleum products

The feasibility of strengthening soils contaminated with heavy-metal ions (HMI) and their simultaneous neutralization is examined. Phosphate systems are analyzed thermodynamically on the basis of the parameter ΔG^o _{298_}, which is indicative of possible soil stabilization. Concentration limits of contamination are determined, and mechanisms responsible for neutralization with simultaneous stabilization are analyzed. __________ Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 17–20, March–April, 2008.     

Sorption and bioavailability of heavy metals in long-term differently tilled soils amended with organic wastes

In this study, bioavailability and enrichment studies were focused on Cd, Zn and Cu in two different soils (sandy loam and silt loam), which were treated with compost and sewage sludge, respectively, both under conventional tillage (CT) and no tillage (NT). Long-term NT resulted in a significant increase in Cd and Zn extracted by aqua regia in a soil profile (0-25 cm), especially in the 0-3 cm layer. In the sandy loam, a slight increase in cadmium due to sewage sludge application was observed. Results from EDTA-extractable heavy metal analyses were not consistent but NH(4)NO(3)-extractable concentrations were significantly lower in the NT soil. Bioavailability of heavy metals was reduced in the long-term NT, resulting in lower uptake of Cd and Zn by plants and accumulation in the soil. The effect of tillage on enrichment of heavy metals in soils was more significant than the impact of the fertilisation by means of legally allowable application rates of organic wastes. This work suggests that non-tilled soils enriched in heavy metals should not be amended with organic waste in the long term.     

Total and extractable contents of trace metals in agricultural soils of the Valderas area, Spain

The surface horizons of four agricultural field soils (Mollic ustifluvents, Alfic Xerochrepts, Typic Palexeralfs, Typic Haploxeralfs) were sampled to determine the total copper, cobalt, molybdenum, zinc, chromium, nickel, selenium, cadmium, lead, mercury, lithium and strontium, and were also fractionated by an extraction procedure to estimate the quantities of these trace metals in soluble form. The extractants used were the following: 1.0 N NH4 OAc for lithium and strontium, 0.05 M Na2-EDTA for cadmium, copper, nickel and zinc, 2.5% (w/v) acetic acid for lead, 2.5% (w/v) acetic acid and 2% (w/v) dithizone for cobalt, 2% (w/v) diethyldithiocarbamate solution for selenium, 0.1 NHCl for chromium, and 0.5 NHCl for mercury. The total content of these twelve elements in the four field soils sampled were lower than the levels quoted in the literature, although for different geochemical systems. The percentage of the total element content in soluble form was (except for selenium) generally very low, averaging between 5.5 and 8% for copper, 1.6 and 2.5% for cobalt, 8 and 10% for molybdenum, 1.8 and 2.2% for zinc, 14.2 and 17.7% for chromium, 5.5 and 6.4% for nickel, 30 and 55% for selenium, 8 and 14% for cadmium, 3 and 3.6% for lead, 8.3 and 11% for mercury, 5 and 7% for lithium, and 4.4 and 5.7% for strontium, regardless of the soil type.     

Estimation of migration profiles in England and Wales

"Migration profiles by age have been increasingly used in the analysis of migration data, and a theoretical function has been developed by researchers at the International Institute for Applied Systems Analysis (IIASA). This paper refines the approach by applying the principles of maximum likelihood to the estimation of the coefficients for the function. This enhances the statistical basis and in particular enables [the authors] to carry out tests of similarity between different areas on the basis of the calibrated coefficients. The method is applied to 1971 Census data for the local authorities of England and Wales."     

Inefficiencies in electricity pricing in England and Wales

The combination of competition and regulation established in the electricity industry of England and Wales stimulates production efficiency and thus helps the industry to achieve low costs. Nevertheless this system does have some disadvantages as regards the incentives it presents to generators and to suppliers. These deficiencies arise because Use of System Charges both for Distribution and for Transmission are determined in a way that inadequately reflects the structure and level of marginal costs. Furthermore, the way that profiling for consumers taking less than 100 kW will work is likely to inhibit tariff innovation.     

The influence of weathering and organic matter on heavy metals lability in silicatic, Alpine soils

We investigated the effect of organic matter and weathering on the lability and solid phase speciation of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) in two contrasting subalpine regions in the Italian Alps. Cr, Ni and Cu could be linked to weathering. This was not the case for Pb. Since organic matter (OM) influences the solid phase speciation of heavy metals, the total organic C and N content, the C and N content of different density fractions of OM and also of the labile (oxidised by H₂O₂) and stable (H₂O₂-resistant) fractions were determined. Soil OM stocks were high and soils on north-facing slopes had more OM than the south-facing sites to which they were paired. Density measurements and the H₂O₂ fractionation indicated that the higher OM content on north-facing sites was due to an accumulation of weakly degraded organic material. Due to higher weathering intensity on north-facing sites, the abundance of the EDTA-extractable heavy metals was higher than on south-facing sites. All EDTA-extractable heavy metals showed a good correlation to the water-soluble phenolic concentrations which indicates that the metals were probably translocated as metal-organic complexes. Pb and Cu correlate not only to the light (density < 1 g/cm³) and labile, organic fraction but also to the heavy (density > 2 g/cm³) and stable fraction. High-mountain ecosystems like the Alps are sensitive to changing environmental conditions such as global warming. A warmer climate and the more favourable conditions it brings for biological activity, especially at cooler sites, will probably lead in the short- to mid-term to an increased loss of accumulated, weakly degraded OM. As the Pb and Cu content is significantly related to the labile organic matter pools, the risk exists that an increase in OM mineralisation could affect the storage capacity and mobility of these metals in soils.     

Mobilization of heavy metals from Le An River sediment

The release of sediment-bound heavy metals can have a significant influence on river water quality. Generally speaking, variations of pH and oxygen are among the most important chemical factors that affect the mobility of sediment-bound metals. Recent research has indicated that sulfide, measured as acid-volatile sulfide (AVS), is an important partitioning component of heavy metals. We determined the metal release potential of sediments from the Le An River which receives drainage from a major copper mining operation. We found that the in-situ Cu, Pb, Zn, Cd and As concentrations of the Le An River sediments below the mine are much higher than are the global background values, but that Ni was not elevated. There is potential for mobilization of bound metals to the overlying water, the order of metal release ratio in terms of pH dependencies is Zn > Cu > Cd approximately Pb. Sulfide is not a major binding component for metals in Le An River sediment. It is more likely that the iron and manganese oxides are the most important metal binding components in the sediments of the Le An River.     

Strategic Resource Development Options in England and Wales

This paper describes the options which had to be considered for new water resources in the development of the † National Rivers Authority's water resource strategy for England and Wales. The options included interregional transfers, strategic reservoirs, and a range of unconventional schemes including aquifer recharge, effluent re-use, groundwater abstraction where levels are rising, desalination, and transfer by sea. The main options are described and comparative costs are presented.     

Domestic and agricultural contributions to the inputs of phosphorus and nitrogen to Lough Neagh

Loadings of nitrogen and phosphorus from the major river catchments that contribute to Lough Neagh have been measured for the years 1971–1974. Analysis of this data indicated that there was a very significant correlation between soluble ortho-P loadings and the human but not the animal population densities of the catchments. The land drainage and agricultural contribution of soluble ortho-P to Lough Neagh was 0.14 kg P-ha⁻¹·yr⁻¹ which was about 25% of the measured soluble ortho-P loading to the Lough. It was estimated that the introduction of phosphorus removal treatment at sewage works connected to populations greater than 2000 could curtail 50% of the phosphorus available to support algal growth in the Lough. There was a good correlation between nitrogen fertilisers usage in Northern Ireland and the nitrate concentration in the major rivers.