Volcanic activity is one of the primary sources of arsenic in nature, and chemical forms of arsenic discharged by volcanic activity are inorganic. Kagoshima Bay has active submarine volcano located in the 200 m deep basin of its northern part. Since dissolved inorganic arsenic is more toxic than organic arsenic it is important to understand the dispersion of discharged arsenic in seawater. To estimate the influence of arsenic emitted from the bottom vents seasonal changes in As(III) and As(V) concentrations in seawater were studied. There are few studies on the impact of arsenic discharged by submarine volcanos in the inner bay. The total concentrations of As(III) and As(V) (T-As) in seawater at the background site in Kagoshima Bay was 1.71 ± 0.35 μg L⁻¹ (av. ± s.d.), similar to the world average value of 1.7 μg L⁻¹. The highest T-As value at the nearest point to the submarine volcano, 3.48 μg L⁻¹, was observed in summer. Since the vertical mixing of seawater cannot occur in summer due to the formation of the thermocline, the deep water is strongly affected by volcanic activity. The increase in T-As was caused by the increase in As(III) concentration suggesting the discharge of As(III) from the vents.

火山活动是自然界中砷的主要来源之一，通过火山活动排放的砷的化学形式是无机的。鹿儿岛湾的北部深200 m的盆地中有活跃的海底火山。由于溶解的无机砷比有机砷的毒性更大，因此了解排放的砷在海水中的分散情况非常重要。为了估算从底部通风口排放的砷的影响，研究了海水中As（III）和As（V）浓度的季节性变化。关于内湾海底火山释放的砷的影响的研究很少。鹿儿岛湾本底海水中的As（III）和As（V）（T-As）的总浓度为1.71±0.35μgL ^-1（av。±sd），类似于1.7μgL ^-1的世界平均值。夏季观测到最接近海底火山的最高T-As值3.48μgL ^-1。由于夏季由于形成了温跃层而无法在海水中进行垂直混合，因此深水受到火山活动的强烈影响。T-As的增加是由于As（III）浓度的增加所致，表明As（III）从通风孔中排出。