    Set 1                         Set 2
(Richards, 1977)   (Richmond & Richards, 1978)

ch4 2.00                1.90
ch3 1.70                1.70
nh4 2.00                1.70
nh3 1.70                1.70
oh4 1.60                1.40
oh3 1.50                1.40
sh  2.00                1.80
st  1.80                1.80
zn  0.64                0.64
fe  0.64                0.64