THE MOLECULAR WEIGHT AND ORIGIN OF YELLOW ORGANIC ACIDS

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Abstract
Using gel filtration, we determined the quantity of distribution of yellow organic acids in two forest soils and adjacent stream waters. We also determined the molecular weight distribution of these yellow organic acids and found the major fraction, the mobile fulvic acid fraction, to have a molecular weight in the range of 810 to 930. To calibrate the gel columns, we used standards chemically similar to yellow organic acids, rather than dextrans, which had been used by previous authors. If the molecular weights of yellow organic acids determined previously are recalculated using the new standard curve, the previous gel-filtration values agree quite well with those reported in this paper.Gel filtration of soil solutions from two forest soils demonstrated that yellow organic acids originated in the upper soil profile and that soil permeability strongly influences their concentration in adjacent stream waters. Because yellow organic acids originate in the soil, they can be referred to as mobile fulvic acids. Soil solutions passing through the lower B horizons had decreased mobile fulvic acid concentrations; thus the deeper B horizons were able to absorb and decrease mobile fulvic acids in the solutions derived from the upper profile. Using gel filtration, we determined the quantity of distribution of yellow organic acids in two forest soils and adjacent stream waters. We also determined the molecular weight distribution of these yellow organic acids and found the major fraction, the mobile fulvic acid fraction, to have a molecular weight in the range of 810 to 930. To calibrate the gel columns, we used standards chemically similar to yellow organic acids, rather than dextrans, which had been used by previous authors. If the molecular weights of yellow organic acids determined previously are recalculated using the new standard curve, the previous gel-filtration values agree quite well with those reported in this paper. Gel filtration of soil solutions from two forest soils demonstrated that yellow organic acids originated in the upper soil profile and that soil permeability strongly influences their concentration in adjacent stream waters. Because yellow organic acids originate in the soil, they can be referred to as mobile fulvic acids. Soil solutions passing through the lower B horizons had decreased mobile fulvic acid concentrations; thus the deeper B horizons were able to absorb and decrease mobile fulvic acids in the solutions derived from the upper profile. © Williams & Wilkins 1981. All Rights Reserved.