Abstract: The Deepor Beel is a permanent, freshwater lake at the southwest
corner of Guwahati in the southern bank of the Brahmaputra River and the Beel
serves as the major storm water storage basin for Guwahati city. It is
recognized as a Ramsar site (No. 1207) in 2002. The water quality of the Beel
is threatened in recent times by excessive fishing activities, hunting of water
birds, pollution from pesticides and fertilizers, and infestation by water
hyacinth Eichhornia crassipes. The present work reports on bimonthly monitoring
of macro and micro nutrients including nitrate, phosphate, potassium, boron,
copper, iron, zinc at 13 different sites and three different depths of the
water column. The impact of the nutrients on chlorophyll (a, b and c) contents
of the wetland were also monitored. Each parameter was monitored 202 times in
total. The measured values were subjected to analysis of variance test, which
indicated important temporal, spatial and depth-wise correlations for the
parameters. The ratios of total nitrogen to total phosphorus for the water is
mostly <10 and the Trophic State Index is >70.0, both of which point to a
phosphorus-enriched state and water approaching eutrophic conditions. The
results indicate a serious degradation in quality of the water mostly due to
human interferences.
Keywords: Wetland, nutrients, chlorophyll, trophic state index, Deepor Beel
