The Acute And Chronic Toxicity Of Cadmium, Zinc And Organic Pesticides To Daphnia

Biological monitoring was one among important parts of water quality monitoring, and because of the differences in concentration etc, the impact of hazardous materials to organism leaded the acute or chronic reaction.On the basis of the preliminary studies, this study chose self-selection Daphnia carinata and Ceriodaphnia quadrangular as the biological materials, in the aquatic environment of relatively long-term low concentration of cadmium (heavy metals) or PCP-Na (organochlorine pesticides), researched the effects to reproduction ability of Daphnia (Daphnia reproductive cycle, reproduction numbers and young Daphnia death rate), aimed at discussed the chronic toxicity phenomena causing by cadmium and pentachlorophenol sodium and different sensitivity of Daphnia. In addition, studied the influence of cadmium, zinc (heavy metal), and triazole phosphate, sodium pentachlorophenol (organophosphate, organochlorine pesticides) to enzyme activity of acety lcholinesterase (one of the key enzymes in the nervous system) and the Na+,K +-ATP enzyme (one of the key enzymes of energy systems) in Daphnia carinata. The purpose was deeply understanding the effects of heavy metals or pesticides to nerve and energy system in Daphnia, exploring the reason of acute poisoning of Daphnia brought about the changes of phototactic ability, provided the scientific basis for aquatic environment biological monitoring. According to research, the conclusions was following.In the water environment with three different concentration of Cd2+ or PCP (0.032mg/L,0.056mg/L and O.lmg/L), observed Daphnia carinata, Daphnia magna and Ceriodaphnia quadrangular netted respectively and consecutively for eight generation. Found that the mortality of three juvenile Daphnia was increasing with the increasing concentration of these toxic substances. However, the reproduction rate of Daphnia was discrepant in different Daphnia species. Daphnia magna reproduction rate increased with the decline in toxic concentration; the reproduction of Daphnia carinata and Ceriodaphnia quadrangular netted increased in low toxic concentrations, decreased in high concentration (viz low concentration stimulated ovulation, but declined in the quality of young Daphnia, the mortality rate was significantly increased). Showed that the influence of cadmium and PCP to reproduction capacity in three Daphnia species was different.Reproductive cycle of Daphnia Carinata, Daphnia magna and Ceriodaphnia quadrangular were lagged with the increased concentration of Cd2+ and PCP-Na. In the normal water environment, Daphnia began to lay around in 7 days;but in the highest concentration (0.1 mg/L), the average spawning period was 10.4 days,3.4 days later than the control group.In single poison water environment (Cd2+,Zn2+,triazophos and PCP-Na), activity of Daphnia carinata acety lcholinesterase and Na+,K+-ATP enzyme was declined with increased concentrations of toxic substances in the solutions.At low concentrations, enzyme activity declined sharply, leveled off gradually with the increasing of toxic concentration.In the water environment where two poison coexisted (heavy metals Cd2+,Zn2+ and pesticides triazophos and PCP-Na), AChE activity of Daphnia carinata compared with single toxic effects, showing three results:the first, enzyme activity was significantly reduced, such as Daphnia carinata biological toxicity was significantly stronger than a single toxic, both showed synergism between toxic by Cd2+ and triazophos coexistence. Second, the activity had no significant changes,such as Zn2+ and triazophos coexistence. The influence of the enzyme was similar to the presence of a single poison. Third, the activity of the enzyme was significant increase, such as 0.62mg/L of sodium pentachlorophenol in to Zn2+ solution, the enzyme activity was increaser than the single the presence of poison, showing antagonism of two poisons.Compared with single toxic effects, the activity of daphnia carinata Na+,K+-ATP enzyme in the coexistence of the two poison in the water environment (heavy metals Cd2+,Zn2+ and pesticides triazophos and PCP-Na in pairwise groups) showed two phenomena. First, the activity of the enzyme had no significant changes, such as a constant Cd2+,Zn2+ adding into pentachlorophenol sodium or triazophos, the activity of daphnia carinata Na+, K+-ATP enzyme had no significant change compared with single toxic effects. Second, the activity of the enzyme had a significant increase, such as by adding a constant concentration of triazophos or pentachlorophenol sodium into Cd2+,Zn2+,the enzyme activity increased compered with that of a single toxic,both toxic showed antagonism.