Trace oxyanions and their behaviour in the rivers Porong and Solo,the Java Sea and the adjacent Indian Ocean

During the Snellius-II Expedition (theme 5) dissolved and particulate concentrations of As(III), As(V), Sb(III), Sb(V), Se(IV), Mo, U, V, Au and W were measured in the Kali Porong and Bengawan Solo, Strait Madura, the Java Sea and the adjacent Indian Ocean.The estuarine mixing behaviour of Mo, U and V was found to be conservative. Arsenic behaved in a conservative manner during the wet period, while removal was observed in the high salinity region of the Solo and Porong during the dry season. The exceptionally high vanadium concentration in the rivers Porong and Solo, which is more than 10 times higher than that in the world rivers, is connected with leaching of volcanic rock; dissolved concentrations of Au, W and Mo are also higher. Apart from V and Au, the dissolved concentrations in the Java Sea and in the Indian Ocean compare well with average ocean values.