Characterization of Iron and Organic Carbon Colloids in Boreal Rivers and Their Fate at High Salinity

Autor: Simon David Herzog, Per Persson, Ulf Olsson, Emma S. Kritzberg, Luigi Gentile
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Atmospheric Science
010504 meteorology & atmospheric sciences
XAS
DLS
Soil Science
Nanoparticle
Atmospheric Composition and Structure
Aquatic Science
Biogeosciences
01 natural sciences
Biogeochemical Kinetics and Reaction Modeling
Colloid
chemistry.chemical_compound
Oceanography: Biological and Chemical
Paleoceanography
Dynamic light scattering
Limnology
size distribution
Fe speciation
Surface charge
Global Change
Instruments and Techniques
natural colloids
Research Articles
0105 earth and related environmental sciences
Water Science and Technology
X-ray absorption spectroscopy
Geochemical Cycles
Ecology
Paleontology
Forestry
Biogeochemistry
Mineral Physics
Salinity
Oceanography: General
Geochemistry
chemistry
Environmental chemistry
Hydroxide
Particle size
Hydrology
Cryosphere
Biogeochemical Cycles
Processes
and Modeling
X‐ray
Neutron
and Electron Spectroscopy and Diffraction
Research Article
Zdroj: Journal of Geophysical Research. Biogeosciences
ISSN: 2169-8961
2169-8953
Popis: Riverine colloids are important carriers of macronutrients, trace metals, and pollutants into marine waters. The aim of the current study was to extend the understanding of iron (Fe) and organic carbon (OC) colloids in boreal rivers and their fate at higher salinities. X‐ray absorbance spectroscopy (XAS) and dynamic light scattering (DLS) were combined to explore Fe speciation and colloidal characteristics such as size and surface charge and how these are affected at increasing salinity. XAS confirmed the presence of two Fe phases in the river waters—Fe‐organic matter (OM) complexes and Fe(oxy)hydroxides. From DLS measurements on filtered and unfiltered samples, three particle size distributions were identified. The smallest particles (10–40 nm) were positively charged and suggested to consist of essentially bare Fe(oxy)hydroxide nanoparticles. The largest particles (300–900 nm) were dominated by Fe(oxy)hydroxides associated with chromophoric molecular matter. An intermediate size distribution (100–200 nm) with a negative surface charge was presumably dominated by OM and containing Fe‐OM complexes. Increasing the salinity resulted in a removal of the smallest distribution. Unexpectedly, both the intermediate and largest size distributions were still detected at high salinity. The collective results suggest that Fe(oxy)hydroxides and Fe‐OM complexes are both found across the wide size range studied and that colloidal size does not necessarily reflect either Fe speciation or stability toward salinity‐induced aggregation. The findings further demonstrate that also particles beyond the typically studied
Key Points Three colloidal size distributions occurred in river water samplesPositively charged Fe(oxy)hydroxide nanoparticles were removed at increasing salinityLarger size distributions were less affected by salinity
Databáze: OpenAIRE
Externí odkaz: