16-Limnological Study of a Tropical Wetland of Darbhanga North Bihar with Special Reference of Pollution

Abstract

One hundred and eighteen wetlands of Darbhanga District have been surveyed. East of the town Milkichak wetland spreading within more than two hundred ha and receives effluent of Darbhanga Medical College and Hospital, Laheriasarai (D.M.C.H.) as well as Donar Industrial Belt and sewage of the town polluting the wetland. To find out the degree of pollution of water of wetland, different physico-chemical parameters of water and Species Diversity of macrophytes of wetland were carried out. Five sites including two effluent falling were selected for sampling of water and macrophytes. The seasonal value of pH, temperature, transparency, electrical conductivity, total dissolved solids, dissolved oxygen, free carbondioxide, carbonate, bicarbonate, calcium, magnesium, chloride, total nitrogen and B.O.D. were calculated. The mean annual value of B.O.D. was recorded 18.28 ± 2.44 ppm (site — 1), 18.07 ± 2.36 ppm (site — 2), 5.40 ± 0.90 ppm (site —3) 5.38 ± 0.56 ppm (site — 4) and 4.87 ± 0.56 ppm) (site — 5). The mean value of Species Diversity of 25 macrophytes were tabulated 0.537 ± 0.044 (site — 1), 0.656 ± 0.036 (site — 2), 1.560 ± 0.245 (site — 3), 1.372 ±0.269 (site — 4) and 2.166 ± 0.329 (site — 5). The conclusion was drawn that site — 1 and 2 were heavily polluted, site — 3 and 4 were moderately polluted and site-5 was slightly polluted.