Journal - Arsenic and other heavy metals in the rivers of central Nepal

Arsenic and other heavy metals in the rivers of central Nepal

Steven H. Emerman

Department of Biology and Environmental Science, Simpson College,

Indianola, Iowa 50125, U.S.A

Jour. Nep. Geol. Soc., Vol. 31, 2004, 11-18


Abstract

The objective of this study was to measure fluvial As, Co, Cu, Fe, and Zn in order to determine whether central Nepal has a geographically-limited source of As. Seventeen rivers in central Nepal outside and eight rivers inside the heavily polluted Kathmandu valley were sampled monthly for six months. Outside the Kathmandu valley, fluvial As (11 ± 1 mg/l), Co (110 ± 30 mg/l), Cu (93 ± 4 mg/l), Fe (550 ± 80 mg/l), and Ni (50 ± 3 mg/l) were over 5, 550, 13, and 13 times the global averages for each respective element, while Zn (27 ± 4 mg/l) was very close to the global average. The only statistically significant differences between inside and outside the Kathmandu valley were pH (inside: 7.13 ± 0.06, outside: 8.13 ± 0.06), Fe (inside: 1060 ± 90 mg/l) and Cu (inside: 70 ± 10 mg/l) so that Co, Cu, Ni, and Zn levels inside the Kathmandu valley were all naturally occurring. Fluvial As was correlated both in space and time with pH. Outside the Kathmandu valley, fluvial As decreased when pH decreased, due to the increase in the number of positively-charged sorption sites on river bed sediment. Inside the polluted Kathmandu valley, fluvial As increased when pH decreased, due to the organic complexation of As and the negative correlation between organic matter and pH. Central Nepal has multiple sources of As associated with mineralisation of Co, Cu, Fe, and Ni, but not Pb-Zn.

Member Login
NEWS AND EVENTS
  • May
    21

    Nepal Geological Society has organized a press meeting on the memory of 2015 Gorkha Earthquake on 2075/1/12 at the conference hall of Department of Irrigation, Jawalakhel

  • Feb
    06

    Nepal Geological Society organized a one day workshop on Earthquake Safety Day-2074 in 2074/10/13 at the conference hall of the United World Trade Center, Tripureshwor, Kathmandu, Nepal in association with Private and Boarding School Association Nepal (BAPSON Kathmandu Province).

Activities and Information

Activities of 17th and 18th Executive Committee
Nepal Geological Society
P.O.Box No. 231
Kathmandu, Nepal
FREEPHONE: +977-01-4437874
Email: info@ngs.org.np