U:\2021\BM210482_IBo_Waihi_North_Project\Documents\WNP_Freshwater_Report_May_2022\FINAL_Freshwater_Report_FOR DELIVERY_June 2022\FINAL DELIVERED 17 JUNE 2022\WAI-985-000-REP-LC-0007_Rev0_Freshwater_20220621_FINAL.docx Table 22: Historical range (2005-2021) for heavy metals recorded at OGNZL monitoring sites in the Ohinemuri River in the vicinity of Oceana Gold Waihi, Waihi. Data from sites OC2, OH3, OH5, OH1, OH6, RU1 and drawn from Ryder (2021), see Figure 10 for site locations. All units g/m3;< = below detection limit; HD = hardness dependent20. Parameter Min Max Compliance limits Antimony <0.0002 0.026 0.03 Arsenic <0.0002 0.0046 0.19 Cadmium <0.00005 0.00007 HD Copper <0.0005 0.0031 HD Iron <0.02 0.64 1.00 Lead <0.0001 0.0013 HD Manganese 0.0011 0.88 2.00 Mercury <0.00008 0.0001 0.000012 Nickel <0.0005 0.0058 HD Selenium <0.0002 0.0095 0.02 Silver <0.00001 0.0015 HD Zinc <0.001 0.055 HD 20 Generally, as hardness increases, the toxicity of metals decreases.
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