A video about the New Zealand Army testing the quality of water across Christchurch. After the 4 September 2010 earthquake, the NZ Army developed ties with the Canterbury District Health Board. This relationship continued after the 22 February 2011 earthquake with the NZ Army taking on the role of examining Christchurch's water quality.
Numerous studies have shown that urban soils can contain elevated concentrations of heavy metals (HMs). Christchurch, New Zealand, is a relatively young city (150 years old) with a population of 390,000. Most soils in Christchurch are sub-urban, with food production in residential gardens a popular activity. Earthquakes in 2010 and 2011 have resulted in the re-zoning of 630 ha of Christchurch, with suggestions that some of this land could be used for community gardens. We aimed to determine the HM concentrations in a selection of suburban gardens in Christchurch as well as in soils identified as being at risk of HM contamination due to hazardous former land uses or nearby activities. Heavy metal concentrations in suburban Christchurch garden soils were higher than normal background soil concentrations. Some 46% of the urban garden samples had Pb concentrations higher than the residential land use national standard of 210 mg kg⁻¹, with the most contaminated soil containing 2615 mg kg⁻¹ Pb. Concentrations of As and Zn exceeded the residential land use national standards (20 mg kg⁻¹ As and 400 mg kg⁻¹ Zn) in 20% of the soils. Older neighbourhoods had significantly higher soil HM concentrations than younger neighbourhoods. Neighbourhoods developed pre-1950s had a mean Pb concentration of 282 mg kg⁻¹ in their garden soils. Soil HM concentrations should be key criteria when determining the future land use of former residential areas that have been demolished because of the earthquakes in 2010 and 2011. Redeveloping these areas as parklands or forests would result in less human HM exposure than agriculture or community gardens where food is produced and bare soil is exposed.
A photograph of a sign from the Christchurch City Council, ECan and the Canterbury District Health Board warning people over the contamination in the rivers after the September earthquake. The sign reads, "Warning, contaminated water. Due to sewage overflows this water is unsafe for human contact and activity and is a Public Health Risk. Please keep all people and pets out of contact with the water and do not consume any seafood or shellfish collected from this area". In the background, workers from Treetech clean up wood and leaves from felled trees.