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Phosphorus speciation and solubility in aeolian dust deposited in the interior American West

May 10, 2018

Aeolian dust is a significant source of phosphorus (P) to alpine oligotrophic lakes, but P speciation in dust and source sediments and its release kinetics to lake water remain unknown. Phosphorus K-edge XANES spectroscopy shows that calcium-bound P (Ca−P) is dominant in 10 of 12 dust samples (41−74%) deposited on snow in the central Rocky Mountains and all 42 source sediment samples (the fine fraction) (68−80%), with a lower proportion in dust probably because acidic snowmelt dissolves some Ca−P in dust before collection. Iron-bound P (Fe−P, ∼54%) dominates in the remaining two dust samples. Chemical extractions (SEDEX) on these samples provide inaccurate results because of unselective extraction of targeted species and
artifacts introduced by the extractions. Dust releases increasingly more P in synthetic lake water within 6−72 h thanks to dissolution of Ca−P, but dust release of P declines afterward due to back adsorption of P onto Fe oxides present in the dust. The back sorption is stronger for the dust with a lower degree of P saturation determined by oxalate extraction. This work suggests
that P speciation, poorly crystalline minerals in the dust, and lake acidification all affect the availability and fate of dust-borne P in lakes.

Publication Year 2018
Title Phosphorus speciation and solubility in aeolian dust deposited in the interior American West
DOI 10.1021/acs.est.7b04729
Authors Zhuojun Zhang, Harland L. Goldstein, Richard L. Reynolds, Yongfeng Hu, Xiaoming Wang, Mengqiang Zhu
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Index ID 70196929
Record Source USGS Publications Warehouse
USGS Organization Geosciences and Environmental Change Science Center