Distributions And Influence Factors Of Dissolved Inorganic Antimony And Arsenic In The Yellow Sea And East China Sea

With the development of social economy, antimony and arsenic compound materials have been widely used, resulting in increasing emissions of antimony and arsenic in recent years. Because of the highly toxic of antimony and arsenic, they received extensive attentions due to their bioaccumulation through food web and potential damage to the health of human beings. The Yellow Sea (YS) and East China Sea (ECS) are important marginal seas of the Western Pacific Ocean. They have abundant biological and mineral resources and are famous fishing grounds and seafood base. Therefore, to know the biogeochemical behavior of antimony and arsenic in the YS and ECS has the vital practical significance.Two cruises were carried out in March and October 2011 in the YS and ECS to investigate the biogeochemical behavior of total dissolved inorganic antimony (TDISb, [TDISb]= [Sb(V)]+[Sb(Ⅲ)]), antimonite, total dissolved inorganic arsenic (TDIAs, [TDIAs]= [As(V)]+[As(Ⅲ)]) and arsenite. In addition, a supplementary investigation was conducted aboard the T/V "Nagasaki Maru " in July 2012 in the Tsushima Strait to understand the export of antimony and arsenic in the YS and ECS. The concentrations of antimony and arsenic were measured by Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS). The average concentrations of TDIAs, arsenite, TDISb and antimonite in March 2011 were 18.2 nmol/L±1.4 nmol/L,0.32 nmol/L±.45 nmol/L, 1.79 nmol/L±.53 nmol/L and below the detection limit, respectively. The average concentrations of TDIAs, arsenite, TDISb and antimonite in October 2011 were 16.5 nmol/L ±1.8 nmol/L,0.62 nmol/L±.67 nmol/L,1.97 nmol/L±.44 nmol/L and 0.17 nmol/L±0.08 nmol/L, respectively. The average concentrations of TDIAs and TDISb in July 2012 were 18.0 nmol/L ±2.0 nmol/L and 1.48 nmol/L±0.13 nmol/L, respectively. The dominant species of inorganic antimony and arsenic were antimonate and arsenate in the YS and ECS.High concentrations of TDISb were found in the coastal area, which indicates the effect of terrestrial inputs from the adjacent rivers. The concentrations of TDISb were decreased gradually towards the offshore. The negative relationships between TDISb and salinity in March (r= 0.70, p< 0.01, n= 290) and October (r= 0.77,p< 0.01, n= 205) 2011 infer that the behavior of TDISb is generally conservative in the YS and ECS. The mixing of different water masses is the main factor affecting the distribution of TDISb in the study area. TDISb is used as a tracer to estimate the contributions of different water masses in this study. Through the calculation for section PN in October 2011, the impact of Changjiang Diluted Water (CDW) is dominant within a distance of <120 km from the river mouth. In addition, the CDW affects the surface waters (<30 m) between 120-350 km. However, the contribution of the Changjiang to the deep waters along the PN section is relatively small at distances>350 km where the water is dominated by the incursion of Kuroshio Waters (K.W).The distribution of TDIAs was similar to that of TDISb, with the maximum concentrations occurring in the surface layer of coastal area, which indicates the impact of terrestrial input. However, relatively high concentrations of TDIAs were also found in the near bottom layer in the southeastern YS and the shelf of ECS which is different with that of TDISb. Incorporation of high salinity confirmed that higher concentrations of TDIAs are typical of the Yellow Sea Warm Current (YSWC) and KW, respectively. TDIAs showed nutrient like vertical profile in the study area, with depleting at surface and enrichment in the deep waters. The vertical distribution of arsenite was different with that of TDIAs, with the maximum concentrations occurring in the surface or subsurface layer of the region where high concentrations of Chi a existed. There was significant positive relationship (r= 0.81, p< 0.01, n= 57) between As(Ⅲ)/TDIAs ratios and Chi a at section PN in October 2011, which indicates the biological mediation may be one of the most important factors affected the transformation of arsenic species in the YS and ECS.According to the obtained data, the sources of TDISb and TDIAs in the study area mainly include riverine input, dry and wet atmospheric deposition and inputs from Taiwan Strait Warm Water (TSWW) and KW. While the sink of TDISb and TDIAs is the export through Tsushima Current (TSC) in principle. The contributions from submarine groundwater discharge (SGD), particle sedimentation and biological mediation are ignored due to the lack of relevant data. Through the calculation for sources and sink, the residence time of TDISb and TDIAs in the YS and ECS were 3.7 a±1.8 a and 3.1a±2.1 a, respectively. Compare the concentrations of TDISb and TDIAs to that in other regions of the world, they still remain at natural levels in the YS and ECS.