Water quality and Potamoplankton of the river Buriganga and Gomti: A comparison

Abstract

The studied section of the river Buriganga besets with urban catchment
contained higher values of pH, alkalinity, CO2, conductivity, TDS, SRP, SRS and
NO3-N concentration compared to its counterpart, namely a section of the river
Gomti having rural catchment characteristics. The mean values for a period of six
months for the river Buriganga were 8.34, 1.48 meq/l, 8.49 mg/l, 686 μS/cm,
155.17 mg/l, 493 μg/l, 36.07 mg/l and 810.28 μg/l for pH, alkalinity, CO2,
conductivity, TDS, SRP, SRS and NO3-N, respectively. While the same for the
river Gomti was 7.86, 1.18 meq/l, 5.42 mg/l, 284.44 μS/cm, 79.91 mg/l, 188.37 μg/l,
26.41 mg/l and 203.99 μg/l, respectively for pH, alkalinity, CO2, conductivity,
TDS, SRP, SRS and NO3-N. In the river Gomti, the concentration of DO was
better (7.87 mg/l) compared to that of river Buriganga (5.53 mg/l). Because of a
hilly origin of the river Gomti and availability of sediments in its water, the
underwater light climate was poor compared to the river Buriganga. The Secchi
depth recorded for Gomti and Buriganga were 0.26 and 0.54 m, respectively.
Both the rivers were found diatom dominant in terms of population but the
species prevailed were different. Fragillaria virescens Ralfs was the dominant
diatom of the river Buriganga. Its density ranged from 6.5-11.09×105 ind/l which
was the highest compared to the population of all other groups of
potamoplankton. In Gomti another diatom namely, F. pinnata Ehrenberg was
dominant and the density of which ranged from 8.45 - 12.65 × 105 ind/l.
Community structure of the potamoplankton revealed 30 species from the river
Buriganga and 22 species from Gomti. The study reveals that relatively higher
concentration of nutrients prevails in the water of the river course having urban
catchment characters compared to the rural ones.