Major ion and trace metal concentrations and physicochemical parameters were measured over a full tidal cycle in groundwater from reclaimed land adjacent to Rozelle Bay in Port Jackson, Sydney, Australia. Materials used for reclaiming the land (construction material waste or dredged marine sediment) predominantly influenced the ion and trace element compositions of the groundwater. The redox behaviour and composition of the soil profiles influenced the behaviour of redox-sensitive elements in the groundwater, for example Mn and Fe. When the water table recedes in drier periods, oxygen ingress can lead to biologically catalysed oxidation reactions resulting in a reduction in pH and an associated increase in the concentration of some trace elements. The dredged marine sediment contains a considerable fraction of shell fragments, leading to elevated bicarbonate levels in the groundwater, which in turn limits some trace element and major ion concentrations. The groundwaters contain higher levels of many trace elements (Cu, Pb, Zn, As, Cr) than occur in seawater and the natural hydraulic gradient may lead to elevated concentrations of these elements entering the estuary.

A large part of the Sydney 2000 Olympic Site at Homebush Bay was reclaimed over several decades using an estimated 9 Mt of domestic, commercial and industrial waste. Past activities, such as reclamation of wetlands, land clearing, shoreline remodelling and industrial practices, have caused an adverse environmental impact on the Homebush Bay site. Core samples (n = 4513) collected from the reclaimed lands of Homebush Bay show that, prior to remediation, soil contaminated by heavy metals (Cr, Cu, Pb, Zn) may have posed a threat to groundwater in the area. Mean Pb concentrations from the three land types at the Olympic site range from 65 to 374 µg/g in reclaimed areas, 78–167 µg/g in landfill areas and 44–52 µg/g in non‐infilled areas, respectively. Heavy‐metal concentrations in soils from non‐infilled areas indicate that these parts of the site were uncontaminated. The distribution of heavy metals in soil samples revealed a close association between elevated concentrations and the presence of fill materials at the site. Metal concentrations were frequently above Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The Olympic Coordination Authority's remediation strategy to clean up the Homebush Bay site included consolidating contaminated waste into landscaped hills, which were capped with impermeable clay and thermal destruction of scheduled waste on site. The primary aims of the current study were to provide a scientific foundation for the remediation/rehabilitation of natural systems, and to make a contribution to the Olympic Coordination Authority's Development Plan and Environmental Management System for the site.

Cobalt, Cr, Cu, Fe, Mn, Ni, Pb, Zn and As concentrations in the grain size and elemental normalization using Fe in gravel-free total soil ((X m /Fe) total sample ; X m = Cu, Pb, Zn, etc.) were used to determine the influence of variable grain size on the concentration of anthropogenic trace metal contaminants in the reclaimed area adjacent to Port Jackson, Sydney, Australia. Trace metal concentrations in soils in reclaimed area are greatly influenced by the heterogeneous nature of the waste materials buried at the site. The confounding effects of variable grain size in soils can be reduced by analyzing the contaminant concentration of the material after removing >2 mm size in sample. An example from Sydney Harbour is used to demonstrate the comparability between grain size normalized data and elemental normalized data using Fe in soils from reclaimed areas. Results from the current study reveal that the vertical distribution of trace metal concentrations in soils is remarkably similar between the grain size and elemental normalization, using Fe. Normalization methods might be beneficial in overcoming texturally driven variations of contaminant concentrations in soils in the reclaimed or infilled land area.

The present study compared the geochemistry of saline and freshwater percolating through columns containing soils sampled from reclaimed land adjoining Sydney Harbour, Australia. The investigation assessed the flux of contaminants from the soil and, hence, estimated the affect of reclaimed land (using construction waste or dredged sediment) on the adjoining aquatic environment. Leachate samples were collected weekly for 22 weeks and were monitored for pH, Eh (redox potential), electrical conductivity, dissolved oxygen, major elements and heavy metals. In the early stages of the experiment (until approximately Week 12), the concentrations of the major elements in water percolating from the two columns were similar. Differing pseudo-steady-state conditions were reached in the columns after approximately 14 weeks. Sodium and Cl are weakly sorbed onto surface sites of the material in the saline column. The exchange of Na with other cations results in an increase in the aqueous concentrations of Ca, K and Mg in this column. As the parallel field concentrations are considerably higher than those measured in the column experiments, and are much higher (by orders of magnitude) than those measured in seawater, results of the fresh and saline water column tests strongly indicate that elevated concentrations of trace metals probably enter the estuary by tidal action and during periods of rainfall.

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