Some chemical features of two Papuan fresh waters (Papua New Guinea)

Abstract

The Purari River in Papua (Papua New Guinea) is a tropical river with ionic dominance similar to that of the world average river water, i.e. Ca > Mg > Na > K, and HCO₃ > (SO₄?) > Cl. As the sulphate concentration was not determined, the anionic trend still needs to be further investigated. The Na:Ca as well as the Ca + Mg:Na + K ionic ratios suggest that chemical weathering in the highlands is the dominant source of dissolved solids, and that it determines the chemistry of the lower course of the Purari River. Among the waters investigated, the Purari River, in its lower course, has a total salinity higher than that of the Sirinumu impoundment, and lower than that of the Sepik River. The low concentration of solutes in the Sirinumu impoundment near Port Moresby indicates that oligotrophication can be expected in reservoirs built on Papuan rivers.