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Spatial Distribution and Location of Natural Organic Matter on Sediment Particles by Scanning Electron Microscopic Analysis and the Development of a New Persistent Organic Pollutant–Sediment Kinetic Desorption Model
Author(s) -
Clay Marra M.,
Morgan Jack A.,
Dunnivant Frank M.
Publication year - 2021
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.4915
Subject(s) - sediment , sorption , organic matter , particle (ecology) , environmental chemistry , total organic carbon , detritus , desorption , pollutant , chemistry , adsorption , geology , geomorphology , paleontology , oceanography , organic chemistry
Abstract Natural organic matter (NOM) has long been shown to be the dominant factor in determining equilibrium and kinetic processes during sorption and desorption phenomena in sediment and soil experiments. Although several models have been suggested for predicting these processes, few offer mechanistic interpretations because the spatial location of organic matter on sediment particles is unknown. This investigation manually examined sediment particles from multiple locations, containing varying concentrations of NOM, using scanning electron microscopy with energy dispersive X‐ray spectroscopy to determine the types of particles present by categorizing them as individual particles, aggregates, and “other” (detritus, algae, etc.). These types of particles were subsequently analyzed for their elemental composition, specifically the spatial location of carbon. By creating a carbon map of each particle, this investigation has determined that organic matter tends to occur in 2 forms: large aggregates or dispersed across individual sediment particles. These findings were then used to propose a more mechanistically sound mathematical model for pollutant desorption phenomena, assigning the traditional labile kinetic release component to the dispersed NOM spread randomly across sediment particles and the nonlabile kinetic release component to diffusion from densely packed NOM aggregates. Environ Toxicol Chem 2021;40:323–332. © 2020 SETAC