1. An analysis of dredged sediments from a stormwater retention basin revealed a high concentration (in mg/kg) of the heavy metals Fe, Al, Zn, Cu, Pb, Cr, Ni and Cd. The retention basin receives runoff from a watershed that recently has seen an increase in industrial activity. A study is to be conducted with the following objectives: (i) quantify the upstream generation of heavy metals and (ii) assess the settleability of heavy metals through an investigation of the partitioning of heavy metals into different size fractions. Develop a monitoring programme to study storm runoff from a sub-catchment within the watershed having an area of 80 ha of which 85% is industrial and 10% road. The sampling point is a large U-drain 2m in depth and 3 m wide.
Your monitoring programme should include the following considerations:
(i) Equipment selection - provide details of the equipment you would use and give reasons for your choice.
(ii) Suggest a possible sampling plan for the hydrograph shown (Q is in m3 /min).
(iii) Provide details of the sampling protocol to be adopted (sample bottles, sample preservation, field preservation, blanks, ...)
(iv) Procedure for size fractionating the samples.
(v) Laboratory analysis methodology to be used. Give details on the standard methods, instrument and detection limits. Standard methods for heavy metals analysis exist, you should look them up. You should choose a method that best suits the concentrations that you are expecting.
(vi) Of the heavy metals listed, which would you expect is least likely to be anthropogenic in origin? Why?