Record of rapid catchment urbanisation preserved in estuarine sediments, Pakuranga Creek, Auckland
Fig 3: Record of rapid catchment urbanisation preserved in estuarine sediments, Pakuranga Creek, Auckland. The first appearance of 137Cs at 98 cm depth dates this sediment horizon to the early 1950s (Fig 3a). Average sediment accumulation rates of 26 mm/yr during this urbanisation phase increased ~30 fold over pre-deforestation values of less than 1 mm/yr. The onset of catchment urbanisation in 1960 coincides with the transition from sand to mud (i.e., clay and silt) deposition at 90 cm depth (Fig. 3b). Concentrations of copper, lead and zinc also start to increase above background values at this time (Fig. 3c). These high-resolution sedimentation records are particularly valuable for developing our understanding of how human activities on the land impact estuarine and coastal receiving environments (Source: Swales et al., 2002).
