Behaviors of dissolved antimony in the Yangtze River Estuary and its adjacent waters

Abstract

Antimony is a naturally occurring and cumulatively toxic element. With increasing concern as an inorganic contaminant, research on its environmental behavior is becoming a necessity. However, very little is known about this element. To further understand its biogeochemical behaviors and roles in the ecosystem, the main species of dissolved inorganic antimony (Sb(III) and Sb(V)) in Yangtze River Estuary and its adjacent waters were determined by hydride generation and atomic fluorescence (HG-AFS) in our study. Results show that in surface water, the concentration for Sb(III) and Sb(V) were in the range 0.029 μg L⁻¹∼0.736 μg L⁻¹ and 0.121 μg L⁻¹∼2.567 μg L⁻¹, with averages of 0.152 μg L⁻¹ and 0.592 μg L⁻¹, respectively. While concentrations of Sb(III) and Sb(V) in the bottom layer were much lower, ranging from 0.023 μg L⁻¹ to 0.116 μg L⁻¹ (average of 0.050 μg L⁻¹) and from 0.047 μg L⁻¹ to 0.441 μg L⁻¹ (average of 0.194 μg L⁻¹), respectively. Data analysis further demonstrates that the major processes controlling antimony geochemistry in the area are riverine input, atmospheric deposition, incursion of Taiwan Warm Current, and release from particulate phase. The surface-enrichment and bottom-depletion depth profile reveals it does appear as a mildly scavenged element but is less like arsenic than previously believed. Sb(V) was the predominant speciation in aquatic environment of our research, and Sb(III) was a minor constituent of the total antimony. Regarding the adsorption–desorption process onto SPM, Sb(III) has a higher affinity to particulate phase than Sb(V). Furthermore, the significant correlation between antimony and nutrients indicates it is an element with great biological potential, which is also an important behavior for antimony.