Geochemical characteristics and water quality assessment in the Mt. Changbai volcanic field, Northeastern China

The chemistry of groundwater is an important determinant of water quality, which is vital to human health and the ecosystem. It is estimated that 10% of the worldwide population lives in the vicinity of an active volcano; in these regions, the quality of the water could greatly affect crop yield and soil fertility. The Mt. Changbai volcanic field (CVF), located on the border between China and North Korea, is the most well-preserved typical forest ecosystem in eastern Asia, providing various ecological services to human beings. Many types of water bodies, including hot springs, cold springs, and surface water bodies (e.g. rivers and pools) are distributed in the volcanic field. In this study, the geochemical characteristics of these water types, the quality of the water for irrigation purposes, as well as the water quality-related natural mechanism of the water chemistry in the CVF were systematically studied. The results indicate that the hydrochemical characteristics of the water samples in the CVF show the obvious difference between the volcanic cone and the peripheral areas. Significant spatial variation in the water quality was found in the CVF, where water in the peripheral areas was found to be of better water quality than that in the volcanic cone. The hot spring water in the CVF is not only unsuitable for drinking, but also unsuitable for irrigation. Water-rock interactions, ion exchange, and the addition of magmatic volatiles as well as atmospheric and anthropogenic sources are the main source and controlling factors of ions in the water in the CVF. The results of this study can be used as a reference for the sustainable management of groundwater resources in dormant volcanoes.