Behavior of dissolved inorganic arsenic in the Yellow Sea and East China Sea

Plant Nutrients and Trace Elements from the Changjiang Watersheds to the East China Sea

“…Furthermore, surface waters in the shelf area of the East China Sea can have As (III)-to-TDIAs ratios that are twofold-fourfold higher than those of near-bottom samples (cf. Ren et al 2010). In the East China Sea, the ratio of As (III) to TDIAs in water samples has a positive correlation with chlorophyll a (γ 2 = 0.5-0.8).…”

“…Indeed, the ratio of As (III) to TDIAs increases exponentially when the concentration of PO 4 3-is smaller than 0.1-0.2 μM in the water column, with an apparent As-to-P stoichiometric molar ratio of 2.0 × 10 −3 to 2.5 × 10 −3 , which is similar to values from other coastal waters (cf. Ren et al 2010). The implication is that, in the case of phosphorus depletion (i.e., phosphate-limited waters) relative to other plant nutrients (e.g., nitrogen), arsenic can be an alternative candidate in the processes of synthetic metabolism of phytoplankton, with As (V) being transformed to As (III) in the surface waters of the East China Sea.…”

“…Further offshore, profiles of dissolved arsenic in the water column of the East China Sea show that it is regulated by a combination of metabolism and changes in boundary influxes (Ren et al 2010). Briefly, the influxes from Kuroshio waters and land sources (e.g., the Changjiang) have a high As (V)/As (III) ratio relative to the shelf waters (i.e., SMW), although As concentrations from the Changjiang (20-40 nM) can be a factor of two higher than KSW (i.e., 10-15 nM) and KSSW (15-20 nM) (Yao et al 2007;Ren et al 2010) (Fig.…”

“…Briefly, the influxes from Kuroshio waters and land sources (e.g., the Changjiang) have a high As (V)/As (III) ratio relative to the shelf waters (i.e., SMW), although As concentrations from the Changjiang (20-40 nM) can be a factor of two higher than KSW (i.e., 10-15 nM) and KSSW (15-20 nM) (Yao et al 2007;Ren et al 2010) (Fig. 5.8).…”

“…Dissolved concentrations of As and Se and their chemical speciation [i.e., As (III/IV) and Se (IV/ VI)] were determined by hydride generation and atomic absorption spectrometry (HG-AAS) and/or atomic fluorescence spectrometry (HG-AFS) (Yao 2005;Ren et al 2010). Dissolved Al was determined by fluorescence measurements after complexion with lumogallion and extraction into n-hexanol (Zhang et al 2000).…”