Heavy Metal Concentrations in and Around Households Near a Secondary Lead Smelter

Housedusts and garden soils were sampled in 14 houses in the vicinity of a secondary Pb smelter and analysed for concentrations of Pb, Zn, Cu, Cd, As, and Hg. Sixty-one topsoil samples were also taken from a 2 km² grid covering the smelter grounds and surrounding residential areas and analysed for concentrations of Pb, Zn, Cd and Cu. Contour maps generated from the grid data indicate significant contamination in the area (maximum Pb concentration 58 500 g g^-1), particularly down-wind of the smelter grounds. A geometric mean Pb concentration of 2225 g g^-1 was recorded in garden soil and similarly elevated levels were recorded for Zn, Cd, As and Sb. In housedusts, a geometric mean Pb concentration of 1668 g g^-1 was observed. Whilst housedust metal concentrations were generally elevated, compared to other urban or residential areas, there appears to be a large degree of attenuation of the metals between the exterior and interior environments of the homes studied. A significant correlation was not recorded between metal concentrations of garden soils and housedusts. There were significant correlations for: distance from the smelter against garden soil metal concentrations; garden soil metal concentrations against each other; housedust metal concentrations against each other; and house age against garden soil metal concentrations.     

Contamination from historic metal mines and the need for non-invasive remediation techniques: a case study from Southwest England

The UK is legally required by the EU Water Framework Directive (WFD) to improve the environmental quality of inland and coastal waters in the coming years. Historic metal mine sites are recognised as an important source of some of the elements on the WFD priority chemicals list. Despite their contamination potential, such sites are valued for their heritage and for other cultural and scientific reasons. Remediating historic mining areas to control the contamination of stream waters, whilst also preserving the integrity of the mine site, is a challenge but might be achieved by novel forms of remediation. In this study, we have carried out environmental monitoring at a historic, and culturally-sensitive, lead-silver mine site in southwest England and have undertaken a pilot experiment to investigate the potential for a novel, non-invasive remediation method at the site. Concentrations of Pb and Zn in mine spoil were clearly elevated with geometric mean concentrations of 6,888 and 710 microg g(-1), respectively. Mean concentrations of Pb in stream waters were between 21 and 54 microg l(-1), in exceedance of the WFD environmental quality standard (EQS) of 7.2 microg l(-1) (annual average). Mean Zn concentrations in water were between 30 and 97 microg l(-1), compared to the UK EQS of 66.5 microg l(-1) (average). Stream sediments within, and downstream from, the mining site were similarly elevated, indicating transport of mine waste particles into and within the stream. We undertook a simple trial to investigate the potential of hydroxyapatite, in the form of bonemeal, to passively remove the Pb and Zn, from the stream waters. After percolating through bonemeal in a leaching column, 96-99% of the dissolved Pb and Zn in stream water samples was removed.     

The solid-solution partitioning of heavy metals (Cu,Zn, Cd,Pb) in upland soils of England and Wales

Ninety-eight surface soils were sampled from the uplands of England and Wales, and analysed for loss-on-ignition (LOI), and total and dissolved base cations, Al, Fe, and trace heavy metals (Cu, Zn, Cd, Pb). The samples covered wide ranges of pH (3.4-8.3) and LOI (9-98%). Soil metal contents measured by extraction with 0.43 mol l-1 HNO3 and 0.1 mol l-1 EDTA were very similar, and generally lower than values obtained by extraction with a mixture of concentrated nitric and perchloric acids. Total heavy metal concentrations in soil solution depend positively upon soil metal content and [DOC], and negatively upon pH and LOI, values of r2 ranging from 0.39 (Cu) to 0.81 (Pb). Stronger correlations (r2=0.76-0.95) were obtained by multiple regression analysis involving free metal ion (Cu2+, Zn2+, Cd2+, Pb2+) concentrations calculated with the equilibrium speciation model WHAM/Model VI. The free metal ion concentrations depend positively upon MHNO3 and negatively upon pH and LOI. The data were also analysed by using WHAM/Model VI to describe solid-solution interactions as well as solution speciation; this involved calibrating each soil sample by adjusting the content of "active" humic matter to match the observed soil pH. The calibrated model provided fair predictions of total heavy metal concentrations in soil solution, and predicted free metal ion concentrations were in reasonable agreement with the values obtained from solution-only speciation calculations.     

Topsoil and Housedust Metal Concentrations in the Vicinity of a Lead Battery Manufacturing Plant

The aim of the study was to determine the extent of heavy metal pollution in the vicinity of a lead battery manufacturing plant in the Czech Republic, both in the general environment and within homes. Topsoils (0–5 cm) were sampled from 100 sites along 4 transects which crossed the battery factory, the town centre and outlying rural areas. Housedust samples were collected from 15 plant-workers' homes and 15 non plant-workers' homes located at various distances from the factory. Samples were analysed for levels of Pb, Zn, Cd, Cu, As and Sb, using ICP-AES. Soil concentrations of Pb, Cd, As and Sb peaked at the perimeter fence of the battery factory with Pb levels of up to 12 650 g g> ^-1. Concentrations of these metals decreased exponentially within 500 m of the plant. Whilst the battery factory does appear to be a source of all the metals with the exception of Zn, emissions do not appear to be transported to any great extent over distances of more than 0.5 km. Topsoil and housedust concentrations of Pb, Zn, Cd, Cu, As and Sb in the general Mlada Boleslav area do not appear to be significantly different from those recorded in a large scale survey of urban soils in the United Kingdom. A comparison of housedust Pb concentrations in homes of plant workers and non-plant workers suggests that there may be a small input of Pb into the home environment by battery plant employees.