Table 4: Trace element concentrations (ppm) from coal samples taken from the Four Corners mine (BHP), Black Mesa, and five residences in or near Shiprock, New Mexico. Mean concentrations of trace metals in US coals [23] are in the final column for comparison.

elementBHPBlack MesaNav51Nav56Nav69Nav78Nav151mean US coal

arsenic (As)0.2720.6030.4810.5710.3290.480.36324.0
beryllium (Be)0.8070.1031.130.1010.7440.4650.5592.20
chromium (Cr)3.202.269.833.662.712.334.0515.0
cadmium (Cd)0.0210.0070.0690.0090.0150.0130.0180.470
lead (Pb)9.760.829 19. 7 a 0.7305.461.084.1411.0
manganese (Mn)10.01.9310.03.606.935.139.5643.0
mercury (Hg)0.0160.0260.0270.0290.0150.020.1200.170
nickel (Ni)2.212.213.472.862.091.603.0714.0
selenium (Se)1.700.7702.401.401.701.300.6502.80
antimony (Sb)0.5120.0580.4960.1160.3040.2340.3181.20
cobalt (Co)2.570.5685.130.742.580.9731.7815.0

a. Only one element (lead) in one sample (Nav51) exceeded the U.S. average values in coal for these hazardous air pollutants.