Evaluation of butachlor for control of some submerged macrophytes along with its impact on biotic components of freshwater system

In this investigation, the efficacy of the herbicide butachlor, [N-butoxymethyl-2 chloro-2[1], 6[1] diethyl 1 acetanilide] was tested against few common submerged macrophytes namely Hydrilla [Hydrilla verticillata [L.] Royale], Najas [Najas minor All.], Nechamandra [Nechamandra alternifolia [Roxb.] Thwaites] and Ottelia [Ottelia alismoides [L.] Pers.] of freshwater fish ponds. Almost complete decay of Hydrilla, Nechamandra and Ottelia was achieved at 7.5 L of active ingredient/ha/m butachlor within 15 days while the herbicide showed no negative effect on Najas. However at the same concentration of butachlor, total mortality of zooplankton and water fern Azolla [Azolla caroliniana Lamarck] occurred within seven days. In case of few freshwater fish species like Rohu [Labeo rohita], Channa [Channa punctatus], Anabas [Anabas testitudineus] and Heteropneustes [Heteropneustes fossilis], total mortality occurred upto 90 days after application of the same dose of butachlor but fish survived beyond 120 days of herbicide application indicating degradation of the herbicides

Combined effects of water pH and alkalinity on the accumulation of lead, cadmium and chromium to labeo rohita [hamilton]

Influence of pH [5.5, 7.0 and 8.5] and alkalinity [40 to 200 mg/L as CaCO3] on the accumulation of Pb [NO3]2, CdCl2, H2O and K2Cr2O7 to Labeo rohita [Hamilton] was investigated in the laboratory. Highest accumulation of Pb and Cr in whole fish occurred at pH 5.5 and at alkalinity level of 40 to 46 mg/L as CaCO3 compared to 7.0 and 8.5. In case of Cd maximum accumulation occurred at pH 7.0 and at alkalinity of 100 mg/L as CaCO3 than that of pH 5.5 and 8.5 and alkalinity 42 and 156 mg/L as CaCO3. Maximum accumulation of lead and chromium occurred at total alkalinity level of 40 and 46 mg/L as CaCO3, respectively while maximum accumulation of cadmium occurred at an alkalinity level of 200 mg/L as CaCO3. A significant [p<0.05] linear relationship was demonstrated between increasing pH/ alkalinity and decreasing accumulation in Pb and Cr treatment at all exposure period while for Cd there was no significant linear relationship established