Table 3. Mercury and methylmercury concentrations in dredge tailings and sediment samples Field site Subsamples Material sampled Sample "Total Hg, ng/g" "Total Hg, ng/g" "Methyl Hg, ng/g" size fraction by CVAAS* by CVAFS** by CVAFS** CC1 21CC01WAS Poorly sorted gravel fill (dredge stacker tailings) Bulk 134 0.588 21CC01WBSF Poorly sorted gravel fill (dredge stacker tailings) <63mm 295 1.18 CC2 21CC02WBS Pebbly organic mud Bulk 24.9 0.639 21CC02WASF Pebbly organic mud <63mm 190 2.07 22CC02SBA Organic mud Bulk 102 0.780 22CC02SB Poorly sorted gravel Bulk 30 22CC02SC Poorly sorted gravel >2mm 20 22CC02SF Poorly sorted gravel <2mm 50 23CC02SB Organic mud Bulk 18.1† 0.215†† CC3 21CC03SA Poorly sorted gravel fill (dredge stacker tailings) Bulk 90 21CC03WSAB Poorly sorted gravel fill (dredge stacker tailings) Bulk 109 0.225 21CC03WSFB Poorly sorted gravel fill (dredge stacker tailings) <63mm 269 1.02 CC4 21CC04SA Poorly sorted gravel fill (dredge stacker tailings) Bulk 30 CC5 21CC05S Metamorphic rock pebble composite (from stacker tailings) Bedrock 30 CC6 21CC06S Granitic rock pebble composite (from stacker tailings) Bedrock <10 CC7 21CC07S Poorly sorted gravel Bulk 30 21CC07ASB Poorly sorted gravel Bulk 22.9 0.574 21CC07B Poorly sorted gravel <63mm 275 3.00 CC8 21CC08SC Poorly sorted gravel (placer tailings) >2mm 20 21CC08SF1 Poorly sorted gravel (placer tailings) <2mm 30 21CC08SF2 Poorly sorted gravel (placer tailings) <2mm 60.1 0.387 CC9 21CC09S Nomlaki Tuff Bedrock <10 CC10 21CC10SB1 Poorly sorted gravel (placer tailings) Bulk 70 21CC10SB2 Poorly sorted gravel (placer tailings) Bulk 114 0.299 22CC10SB Poorly sorted gravel (placer tailings) Bulk 110 22CC10SC Poorly sorted gravel (placer tailings) >2mm 90 22CC10SF Poorly sorted gravel (placer tailings) <2mm 150 22CC10SM Poorly sorted gravel (placer tailings) <2mm>63mm 163 0.068 22CC10SFA Poorly sorted gravel (placer tailings) <63mm 326 <1.36 23CC10SB Poorly sorted gravel (placer tailings) Bulk 100 23CC10SF Poorly sorted gravel (placer tailings) <2mm 64† 23CC10SM Poorly sorted gravel (placer tailings) <2mm>63mm 126 23CC10SFA Poorly sorted gravel (placer tailings) <63mm 290 CC11 21CC11SB1 Poorly sorted stream gravel Bulk 40 21CC11SB2 Poorly sorted stream gravel Bulk 118 0.699 21CC11SC Poorly sorted stream gravel >2mm 30 21CC11SF Poorly sorted stream gravel <2mm 60 21CC11SVF Poorly sorted stream gravel <63mm 204 0.775 22CC11SB Poorly sorted stream gravel Bulk 40 22CC11SC Poorly sorted stream gravel >2mm 20 22CC11SF Poorly sorted stream gravel <2mm 70 22CC11SM Poorly sorted stream gravel <2mm>63mm 41.9 0.032 22CC11SFA Poorly sorted stream gravel <63mm 282 <2.50 23CCC11SB Poorly sorted stream gravel Bulk 60 23CCC11SM Poorly sorted stream gravel <2mm>63mm 90 23CCC11SF Poorly sorted stream gravel <63mm 138.5† 0.861†† CC12 21CC12B Organic and iron-rich mud Bulk 160 31.1 22CC12SB Organic and iron-rich mud Bulk 452 6.3 23CC12SB Organic and iron-rich mud Bulk 354† 8.30†† CC13 21CC13SB "Poorly sorted congolmerate, Tehama Fm." Bulk <10 21CC13SC "Poorly sorted congolmerate, Tehama Fm." >2mm <10 21CC13SF1 "Poorly sorted congolmerate, Tehama Fm." <2mm <10 21CC13SF2 "Poorly sorted congolmerate, Tehama Fm." <2mm 2.89 <0.015 21CC13ST Nomlaki Tuff Bedrock <10 CC14 21CC14SB Poorly sorted gravel (dredge stacker tailings) Bulk 50 21CC14SC Poorly sorted gravel (dredge stacker tailings) >2mm 30 21CC14SF1 Poorly sorted gravel (dredge stacker tailings) <2mm 40 21CC14SF2 Poorly sorted gravel (dredge stacker tailings) <2mm 51.0 0.064 CC15 21CC15CL1 Clay-silt (dredge sluice tailings) Bulk 160 21CC15CL2 Clay-silt (dredge sluice tailings) Bulk 134 0.046 21CC15SC1 Coarse sand (dredge sluice tailings) Bulk 90 21CC15SC2 Coarse sand (dredge sluice tailings) Bulk 99.5 <0.015 21CC15SF1 Fine sand (dredge sluice tailings) Bulk 90 21CC15SF2 Fine sand (dredge sluice tailings) Bulk 104 <0.015 CC16 21CC16B Poorly sorted gravel (dredge stacker tailings) Bulk 70 21CC16SB Poorly sorted gravel (dredge stacker tailings) Bulk 202 0.026 21CC16SC Poorly sorted gravel (dredge stacker tailings) >2mm 40 21CC16SF Poorly sorted gravel (dredge stacker tailings) <2mm 140 CC17 21CC17SB Poorly sorted gravel (dredge stacker tailings) Bulk 60 21CC17SC Poorly sorted gravel (dredge stacker tailings) >2mm 20 21CC17SF1 Poorly sorted gravel (dredge stacker tailings) <2mm 40 21CC17SF2 Poorly sorted gravel (dredge stacker tailings) <2mm 29.7 0.101 CC18 21CC18SB1 Poorly sorted stream gravel Bulk 20 21CC18SB2 Poorly sorted stream gravel Bulk 22.5 0.188 22CC18SB Poorly sorted stream gravel Bulk 40 22CC18SC Poorly sorted stream gravel >2mm 10 22CC18SF Poorly sorted stream gravel <2mm 50 22CC18SM Poorly sorted stream gravel <2mm>63mm 10.8 0.524 22CC18SFA Poorly sorted stream gravel <63mm 93.8 4.130 23CCC18SB Poorly sorted sandy stream gravel Bulk 40 23CCC18SM Poorly sorted sandy stream gravel <2mm>63mm 20 23CCC18SF Poorly sorted sandy stream gravel <63mm 69.3† 0.625†† CC19 21CC19SB1 Fluvial flood sand Bulk 20 21CC19SB2 Fluvial flood sand Bulk 13.1 0.020 CC20 22CC20SB Poorly sorted gravel (dredge stacker tailings) Bulk 20 22CC20SC Poorly sorted gravel (dredge stacker tailings) >2mm 10 22CC20SF Poorly sorted gravel (dredge stacker tailings) <2mm 10 CC21 22CC21SB Poorly sorted gravel (dredge stacker tailings) Bulk 20 22CC21SC Poorly sorted gravel (dredge stacker tailings) >2mm 20 22CC21SF Poorly sorted gravel (dredge stacker tailings) <2mm 40 CC22 22CC22SB Poorly sorted sandy gravel (mixed dredge stacker and sluice tailings) Bulk 850 22CC22SC Poorly sorted sandy gravel (mixed dredge stacker and sluice tailings) >2mm 520 22CC22SF Poorly sorted sandy gravel (mixed dredge stacker and sluice tailings) <2mm 1100 CC23 22CC23SB Coarse sand (dredge sluice tailings) Bulk 330 CC24 22CC24SB Poorly sorted gravel (dredge stacker tailings) Bulk 60 22CC24SC Poorly sorted gravel (dredge stacker tailings) >2mm 50 22CC24SF Poorly sorted gravel (dredge stacker tailings) <2mm 90 CC25 22CC25SC Pebbly fluvial sand >2mm 10 22CC25SF Pebbly fluvial sand <2mm 10 CC26 22CC26SB Poorly sorted gravel fill (dredge stacker tailings) Bulk 50 22CC26SC Poorly sorted gravel fill (dredge stacker tailings) >2mm 30 22CC26SF Poorly sorted gravel fill (dredge stacker tailings) <2mm 60 CC28 22CC28SB Black sulfide-bearing mud (precipitate) Bulk 66.4 0.849 CC29 22CC29SB Poorly sorted stream gravel Bulk 70 22CC29SC Poorly sorted stream gravel >2mm 40 22CC29SM Poorly sorted stream gravel <2mm>63mm 19.6 0.029 22CC29SF Poorly sorted stream gravel <63mm 60 156 0.322 23CCC29SB Poorly sorted stream gravel Bulk 20 23CCC29SM Poorly sorted stream gravel <2mm>63mm 30 23CCC29SF Poorly sorted stream gravel <63mm 112.8† 0.548†† CC30 22CC30SB Poorly sorted stream gravel Bulk 40 22CC30SC Poorly sorted stream gravel >2mm 30 22CC30SF Poorly sorted stream gravel <2mm 20 22CC30SM Poorly sorted stream gravel <2mm>63mm 10.7 0.054 22CC30SFA Poorly sorted stream gravel <63mm 45.3 <0.882 23CCC30SB Poorly sorted stream gravel Bulk 30 23CCC30SM Poorly sorted stream gravel <2mm>63mm 30 23CCC30SFA Poorly sorted stream gravel <63mm 76.6† 0.138†† CC31 23CC31SB Poorly sorted gravel (placer tailings) Bulk 110 23CC31SF Poorly sorted gravel (placer tailings) <2mm 145† 23CC31SM Poorly sorted gravel (placer tailings) <2mm>63mm 917 23CC31SFA Poorly sorted gravel (placer tailings) <63mm 589 CC32 23CC32SB Mud Bulk 233 CC33 23CC33SB Mud Bulk 158 CC34 23CC34SB Fine organic mud Bulk 309 CC35 23CC35SB Organic mud Bulk 95.4† 0.582†† CC36 23CC36SB Poorly sorted stream gravel Bulk 30 23CC36SM Poorly sorted stream gravel <2mm>63mm 40 23CC36SF Poorly sorted stream gravel <63mm 182.9† 1.75†† *Analyses performed by ALS Chemex "**Analyses performed by Frontier Geosciences, Inc. except as noted (see methods section)" †Calculated from sequential extraction determinations performed by Brooks Rand LLC "††Analysis performed by Brooks Rand LLC (method same as Frontier Geosciences, see methods section)"