According to their characteristics

arsenic in sediment was classified into four states: water soluble

HCl-extracting

NaOH-extracting and residue. Four arsenic species

i.e. inorganic arsenic As(III) and As(V) and organic arsenic monomethyl arsonate and dimethyl arsonate (DMA) in sediment were analyzed by spectrophotometry after solvent extraction.The results show that there are some rules for the arsenic in sediment. Arsenic concentration for all sampling sites is affected by pollutiou source around that. Arsenic concentration of HCl-extracting state is the highest in the sediment. In HCl-extracting and NaOH-extracting states

inorganic arsenic species is higher than organic arsenic

As(III) is predominant

and DMA is the major organic species.