Physicochemical or geochemical

• Lohr, A. J., Bogaard, T. A., Heikens, A., Hendriks, M. R., Sumarti, S., Van Bergen, M. J., Van Gestel, C. A. M., Van Straalen, N. M., Vroon, P. Z., Widianarko, B., (2005), Natural pollution caused by the extremely acidic crater Lake Kawah Ijen, East Java, Indonesia, Environmental Science and Pollution Research, 12, 89-95, 10.1065/espr2004.09.118