Applied Geochemistry

The Chalk aquifer is the most important British aquifer and is also important over much of northern Europe. Aquifer protection requires a sound knowledge of the baseline conditions and how these might vary, or have varied, with time. This detailed geochemical study of a representative area of Chalk in Berkshire, U.K., includes a consideration of several components: (1) the inputs from the atmosphere; (2) the interstitial water of the soil and the unsaturated zone; (3) the interstitial water in the confined and unconfined sections of the aquifer; and (4) the saturated, mainly fissure flow, along the hydraulic gradient which forms an important water supply of the Thames Valley region.Atmospheric inputs form an important source of some elements, but the dominant chemical characteristics of the Chalk groundwater are acquired during percolation through the soil and the upper unsaturated zone. During saturated flow downgradient the chemistry is modified mainly by incongruent reactions of ...

Due to rapid urbanisation and scarcity of land, most of the urban parks and recreational areas in Hong Kong are built close to major roads or industrial areas, where they are subject to many potential pollution sources, including vehicle exhaust and industrial emissions. An extensive soil survey was conducted in urban parks of Hong Kong to study the current conditions of heavy metals contamination in soils. Soil samples and associated street dusts were collected from more than 60 parks and public amenity areas in old urban districts, industrial areas and New Towns of the territory. Soils were also sampled in the remote country parks to establish the baseline conditions. The total concentrations of heavy metals and major elements in the samples were determined. The results indicate that urban soils in Hong Kong have elevated concentrations of Cd, Cu, Pb and Zn. The parks with high metal concentrations are located in old urban commercial districts and industrial areas, indicating that the major contamination sources in these soils are traffic emissions and industrial activities. In addition, the application of Cd containing phosphate fertilizers may be an important source of Cd in urban park soils. The street dusts have highly elevated Zn concentration, particularly along the main trunk roads. The high Zn content in the street dusts may come from traffic sources, especially vehicle tyres. Selective soil and road dust samples were also analysed for potential chemical speciation by a sequential chemical extraction method. The chemical partitioning results show that Pb and Zn are mainly in the carbonate/adsorbed and Fe–Mn oxide phases, while Cu is largely associated with the organic and sulphide fractions. The high exchangeable Cd in urban soils and high concentration of Zn in street dusts need further investigation for their ecological and health implications.