Sensitivity of Azolla filiculoides to hydrogen sulphide

This study was conducted to clarify the patterns of nitrogen fixation [nitrogenase activity C2H2 - C2H4 reduction] and chlorophyll concentration of Azolla filiculoides under different concentrations of hydrogen sulfide. It was found that hydrogen sulfide reduced the nitrogenase activity and chlorophyll concentration of Azolla. The reduction in the amount of nitrogen fixed under concentration of 10 mg H2S/l was found to be 56% and 72% after 24 and 96 hours of incubation, respectively, while the reduction in chlorophyll content was 25% and 48% after 24 and 90 hours, respectively, under the same conditions. The study showed linear negative correlation between the hydrogen sulfide concentrations and each of nitrogenase activity [r = 0.92] and chlorophyll concentration [r = -0.88]. The results of Azolla are useful and sensitive enough to use as a new sensitive test species in environmental toxicity tests

Acute toxicity of six organophosphorus herbicides tested by nauplii of brine shrimp, artemia sp

The acute toxicity of six organophosphorus herbicides ametryne, gramxone, gesabrime, bladex atrazine pimextra, and igrane on the survival rate of larvae of brine shrimp Artemia sp., was studied. The effect of these herbicides on larvae after 24 hours exposures in 39% saline water and in sea water having low salinity [20%] were estimated graphically. Results show that the sensitivity of larvae exposed to gramaxone, gesabrime, bladex atrazine and pimextra were higher in sea water of low salinity [LC[50] values were 45 mg/1, 90mg/1, 19mg/1 and 47 mg/1 respectively] than in saline one [which were 75 mg/1, 100 mg/1, 35 mg/1 and 54 mg/1; respectively]. On the other hand, ametryne indicates higher activity and toxicity to larvae in saline water