Author(s): Shinichiro Yano; Akihiro Hisano; Herawaty Riogilang; Hayato Kawase; Akira Tai; Akito Matsuyama; Akihide Tada; Kohei Yano; Wei Huang
Linked Author(s): Shinichiro Yano, Akira Tai, Wei Huang
Keywords: Particulate total mercury; Grain size distribution; Bottom sediment; LISST-100X; Suspended solids
Abstract: Mercury in sea water can be transported by advection and diffusion/dispersion processes, and there are exchange processes between air and sea water and one between bottom sediment and sea water. Both of methylmercury and inorganic mercury can exist as both of particulate form and dissolved one in water. Since particulate mercury may attach with suspended solids (SS) in water, the distribution can depend on resuspention and settling of bottom sediments. Thus, in the recent development of numerical model for mercury transport and its fate combination of hydrodynamic model, which can solve the physical oceanographic process such as a flow and a sediment transport, with biogeochemical model to solve methylation-demethylation equilibrium for mercury has been studying. Since 2006, our research group has been conducting monthly monitoring of mercury concentration in sea water in the Minamata Bay, Japan. In 2010 we introduced LISST-100X which can measure in-situ grain size distribution of SS into monthly water sampling. In the present paper, we report these measurement results. In addition, core sampling for bottom sediment was conducted three times in 2010, 2011 and 2012. As a result, the followings were clarified: i) There is significant difference of SS grain size distribution between upper layer and lower one in density stratification; ii) Origin of SS in upper layer can be estimated to exist in except for bottom sediment and load from rivers; and iii) Characteristics of correlation between particulate T-Hg and SS grain size distribution are obvious.
Year: 2013