Diffusion Coefficients and Polydispersities of the Suwannee River Fulvic Acid:  Comparison of Fluorescence Correlation Spectroscopy, Pulsed-Field Gradient Nuclear Magnetic Resonance, and Flow Field-Flow Fractionation

Abstract

Diffusion coefficients of the Suwannee River fulvic acid (SRFA) obtained using fluorescence correlation spectroscopy (FCS), pulsed-field gradient nuclear magnetic resonance spectroscopy (PFG-NMR), and flow field-flow fractionation (FlFFF) were compared as a function of pH (4.0−8.5) and ionic strength (5−500 mM). Diffusion coefficients of the SRFA ranged between 1.9 and 3.5 × 10-10 m2 s-1. These values were fairly constant as a function of both pH and ionic strength and comparable to the limited literature values available. Polydispersity data are shown indicating that there is some degree of size and chemical heterogeneity for this humic sample including a small fraction of SRFA components with a diffusion coefficient smaller than 1 × 10-10 m2 s-1. The results imply that the majority of SRFA components have hydrodynamic diameters between 1.5 and 2.5 nm.

Characterization of Optical and Associated Properties of Marine Colored Dissolved Organic Material (CDOM)

“…Diffusion coefficient (D) and molecular mass distributions (MM) were calculated for the samples. D varied from 3.81 to 4.35 × 10 10 m 2 s -1 which is in the range of values previously published for humic and fulvic acids (1,6). Two different MM fractions (2 peaks), based on the maximum peak intensities, were found in low salinity water samples based on their fluorescence.…”

Environmental Colloids and Particles: Current Knowledge and Future Developments

“…Although average measures are most often quantified, environmental colloids are always polydisperse, often with undefined size distributions. Size distributions can be determined experimentally by field-flow fractionation (FFF) [21,22], electron microscopy [15,23,24] and atomic force microscopy (AFM) [15,25,26] and calculated from fluorescence correlation spectroscopy (FCS) [27][28][29] and dynamic light scattering [30]. Nevertheless, the techniques each have different detection limits and detection windows corresponding to different size ranges (Figure 1).…”

Metallic nanoparticle enrichment at low temperature, shallow CO2 seeps in Southern Italy

“…Whilst sampling challenges in extreme environments (Kadar and Powell, 2006) and the lack of analytical techniques for detection and characterisation of natural NPs (Lead et al, 2000) have prevented in depth study of the actual morphology, mineralogy and chemical properties of the NPs emitted in deep sea hydrothermal fluids until recently, shallow seeps may be a more accessible site for such studies. The contrasting geological settings, distributions, biogeochemistry, and dynamics of vent and seep ecosystems render distinctive characteristics ranging from the source of reduced compounds available for microbial transformation into energy through chemical oxidation, to the nature of the substratum.…”