At the end of experiment three the 20 g of mussel shell material had successfully absorbed an estimated total of 4,044.5 ± 2.4 μg of Zn. Whilst at the end of experiment four the 20 g of mussel shell material had successfully absorbed an estimated total of 18,675.3 ± 78.2 μg of dissolved Zn. Experiment four, loaded a solution containing 100 μg ml-1 Zn and 20 μg ml-1 Cu into the experimental columns three times (Figure 7). In comparison, aqueous Zn and Cu in Auckland stormwater are at much lower concentrations, i.e., approximately 0.2 μg ml-1 and 0.05 μg ml-1 respectively.