Twenty-five years of nationwide ambient metals measurement in the United Kingdom: concentration levels and trends

Ambient air quality has been an important issue for humans and the environment for hundreds of years. More recently, definitive links have been identified between pollutants and adverse effects on human health and on environmental sustainability. Of particular concern since the last quarter of the twentieth century has been the presence of toxic 'heavy metals' in ambient air. In order to measure the concentrations of pollutants, including 'heavy metals', in ambient air, to assess human and environmental exposure, comply with developing legislation, and assess newly introduced abatement strategies, the UK government established nationwide air quality measurement networks in the late 1970s. The nationwide measurement of 'heavy metals' in ambient air began in the late 1970s, and in 1980 was developed into several national networks, aimed at different metals and different emissions sources. These networks were rationalised into the current UK Heavy Metals Monitoring Network in 2003. The data produced by the current scientific operator of the Network, the National Physical Laboratory (NPL), in 2005, marked 25 years of ambient 'heavy metals' measurement in the UK at a nationwide level. This paper celebrates this milestone and provides a novel and critical examination of Network operations, measured concentration levels, and trends, over the last quarter of a century.     

Leaching behaviour of a chromium smelter waste heap

This paper reports the results of geochemical sampling and modelling of leachates from a chromite ore processing residue (C.O.P.R.) pile under rainwater infiltration. The waste pile is located in the north of England and consists of 800,000 m3 of waste. The pH of fresh leachate is similar to that of a solution in equilibrium with portlandite Ca(OH)2, which is a major constituent of the waste. The in-gassing of CO2(g) causes the pH of the leachates to drop along the drainage ditch and calcite precipitation to occur. The extent of in-gassing is dependent upon the flow rate within the drainage ditch. The dissolution of solid solutions containing residual chromate is likely to control chromate concentrations within the leachate.