Heavy metals in suburban gardens and the implications of land-use change following a major earthquake

Urban Farm DB summary

A study in Christchurch, New Zealand, measured heavy metal (HM) concentrations in suburban garden soils and soils at risk of HM contamination due to former land uses or nearby activities. HM concentrations in suburban garden soils were higher than normal background levels, with 46% of urban garden samples exceeding the residential land use national standard for lead (210 mg kg−1), and the most contaminated soil reaching 2615 mg kg−1. Arsenic and zinc also exceeded national standards in 20% of soils. These findings suggest that soil HM concentrations should be key criteria when determining future land use for former residential areas demolished due to the 2010 and 2011 earthquakes, and that 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.