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8 significantly. Differences in total and dissolved metal concentrations would affect WAD cyanide concentrations, and the presence of the green mat-like material, whidh is especially evident in collection pond samples preserved with NaOH, could affect ryanide recovery rates. As discussed above, in both the upper and lower tailings ponds and the collection pond total iron concentrations were higher than dissolved 'iron. At the pH values of the tailings pond colloidal iron is expected to be resent. Total calcium was higher than dissolved calcium in the upper tailings pond, most likely as a result of gypsum precipitation. IrM addition, the collection pond has higher concentrations of copper in unfiltered than in filtered samples. Copper(I) forms stable complexes with cyanide, therefore the complex is much less toxic than HCN. However, iron-cyanide complexes are extremely unstable when subjected to photolysis, which is expected to occur in the tailings ponds and the collection pond. Therefore, differences in iron concentrations in filtered and unfiltered samples could be significant in terms of potential toxicity. This again argues for collection of matched, preferably both unfiltered, samples at al] sampling locations. Total metal concentrations may overestimate the amount of iron, for example, that is available to bind with cyanide because of the digestion step. However, dissolved metal concentrations certainly underestimate the amount of metal available for cyanide complexing because of dynamic equilibrium associated with the solution and solid phases (i.e., transfer of meta] from suspended mltterial to the solution phase, which would then be available for complexing with ryanifle; or direct complexing of cyanide with metals on suspended sediment). For total cyanide concentrations, all unfiltered process-point samples had higher concentrations than did filtered samples. For WAD cyanide determinations, the lower tailings pond had equivalent total and dissolved WAD ryanide concentrations. In upper tailings pond and collection pond samples filtered samples had significantly higher WAD concentrations than did unfiltered samples, again indicating that there are analytical problems with the WAD cyanide determinations in these samples. In addition, as discussed earlier, WAD cyanide concentrations were higher than total cyanide in many of the process- point samples. 33 QUALITY CONTROL ANALYSES AND RESULTS Both the original (05(01!93) and the amended (06/10193) Quality Control Reports are included as Appendix D of this summary report. In some cases Core laboratories used samples from the second third-party monitoring trip to perform spike and duplicate QA/QC analyses. These samples are marked by an asterisk in Appendix D. The job number, 930346, is followed by a dash and a laboratory sample ID (011, etc.). The laboratory sample IDs are handwritten next to the sample IDs on the Chain of Custody Records in Appendix B of this summary report (e.g., RCG-SU is laboratory sample 007, so if the unfiltered lower RCG/Hagler, Bailly, Inc.