Determination of diffusion coefficients of dissolved organic matter in the Churchill River estuary system, Hudson Bay (Canada)

作者：Balch J; Gueguen C^*

来源：Environmental Chemistry, 2015, 12(2): 253-260.

DOI：10.1071/EN14182

Diffusion coefficients (D) and the molecular weight distribution (MW) of 18 dissolved organic matter (DOM) samples collected in the Churchill River estuary system (Manitoba, Canada) were determined using a diffusive cell apparatus. NaN3 addition has been shown to preserve the DOMMWdistribution within 5 weeks of collection whereas the diffusive properties (i. e. D) were strongly influenced by storage conditions, suggesting D must be determined on freshly collected material. Aquatic DOM from the river and estuarine sites was capable of diffusing across a polyacrylamide diffusive gel membrane with mean D values ranging from 2.74 x 10(-6) to 6.98 x 10(-6) cm(2) s(-1) and from 2.42 x 10(-6) to 10.7 x 10(-6) cm(2)s(-1) respectively, congruent with previous studies using humic substances and natural DOM. The molecular weight of the river and estuary DOM samples (similar to 400-830 Da) measured using asymmetrical flow-field flow fractionation (AF4) strongly influenced D, with larger MW DOM having lower D values. Conductivity had a significant negative correlation with D in estuarine samples collected at high and low tides (R-2 = 0.82 and 0.46 respectively). These results suggest that MW and conductivity can significantly influence D of DOM in river and marine-dominated sites respectively.

• 出版日期2015