ADDITIONS AND CORRECTIONS 1991, Volume 25, Pages 1565-1572 Michael J. Barcelona* and Thomas R. Holm: OxidationReduction Capacities of Aquifer Solids. It has been brought to our attention that there are several errors in this publication which should be communicated to interested researchers. We would like to acknowledge the interest and concerns of Mr. Gorm Heron and Dr. Jorn Kristian Pedersen of the Department of Environmental Engineering, Technical University of Denmark, Lyngby, DK, who pointed out the errors in recent discussion. In section 2.2, Oxidation Capacity, eqs 9 and 10 should read oxidation capacity = 4[02] + 8[N03-] + 8[S04’-] + 6[N02-] + 2TOC/72 (9) = {Fe(III)j+ 2{Mn(IV))+ 2TOC/72
(10)
In these cases, the factor of 2 applied to the TOC term was inadvertently left out of the equations. The changes noted above require the correction of calculated entries for total and organic oxidation and reduction capacities in Tables I and 11, respectively. Table I
TOC calcd oxidn capac (mequiv/g) total calcd oxidn capac (mequiv/g) total meaad oxidn capac (mequiv/d
Table I1 Sand Ridge
Beardstown upgradient
downgradient
0.012
0.019
0.020
0.029
0.028
0.025
0.374
0.376
0.410
Sand Ridge TOC calcd reduc capac (mequiv/g) total calcd reduc capac (mequiv/g) total measd reduc capac (meauiv/a)
Envlron. Sci. Technol., Vol. 26, No. 12, 1992
downgradient
0.13
0.19
0.20
0.15
0.20
0.21
0.095
0.111
0.136
There were apparently some minor arithmetic errors involved in correcting the calculated oxidation and reduction capacities for Fe and Mn species to dry weights of total sediment stemming from the use of incorrect original weights which may have a 3 4 % effect on the total capacities. It should be recognized that these errors and those noted above do not affect the nature of our original conclusions that the calculated oxidation capacities do not account for the total measured capacity. Indeed, the nature of “organic” constituents which might act as oxidizing agents (part of the oxidation capacity) remains in question. In the case of the reduction capacities, these corrections to the calculated organic capacities increase these values above those measured. This tends to reinforce the importance of organic matter in the redox poising of aquifer/groundwater systems. It should be noted that Dr. Pedersen has been making similar determinations of redox capacity in samples from a variety of subsurface environments and has noted substantial contributions of both organic matter and reduced sulfur species to the reduction capacity results. We regret any inconvenience or confusion which these errors may have caused the readership of ES&T.
2540
Beardstown upgradient
