『Abstract
Two hundred and forty water samples (in four seasons) and seventeen
sediment samples have been analyzed to monitor the natural and
anthropogenic influences on the water and sediment chemistry of
the Dal Lake, Kashmir Himalaya. The scatter diagrams [(Ca+Mg)/total
cations (TZ+), (Ca+Mg)/HCO3, (Ca+Mg)/(HCO3+SO4), (Na+K)/TZ+;
(Ca+Mg)/(Na+K)] and the geological map of the study area suggest
predominance of carbonate and silicate weathering. Lower pH and
high total dissolved solids, electrical conductivity and NO3- values in the Gagribal basin and
in some patches of other basins reflect anthropogenic inputs in
the form of sewage from surrounding population, houseboats, hotels,
etc. The Dal Lake is characterized by high chemical index of alteration
(CIA: 87-95), reflecting extreme weathering of the catchment area.
Relative to the average carbonates, the lakebed sediments are
enriched in Al, Ti, Zn, Cu and Co and depleted in Ni and Mn. Compared
to the post-Archean Shale the sediments have higher Al, Zn and
Cu contents and lower Ni and Co. There are distinct positive anomalies
of Al, Mn, Zn and Cu and negative anomalies of Ni and Pb with
respect to the upper continental crust. Geoaccumulation index
(I geo) and the US Environmental Protection
Agency sediment quality standards indicate that the Gagribal basin
and some patches of the Nagin basin are polluted with respect
to Zn, Cu and Pb. These data suggest that the Dal Lake is characterized
by differential natural and anthropogenic influences.
Keywords: Geochemistry; Dal Lake; Weathering; Anthropogenic activity;
Pollution; Erosion; Geoaccumulation index; Kashmir Himalaya』
Introduction
Study area
Methodology
Results and discussion
Water chemistry
Chemical weathering of drainage basin
Chemical evolution
Sediment chemistry
Sediments as pollution indicators
Conclusions
Acknowledgements
References