Residue And Degradation Of Oxine-copper In Paddy Field And Its Toxic Effects

In order to study the residue, degradation and ecological environment effects, determine ecological environment safety and guide scientific, reasonable application of oxine-copper in paddy field. This paper established analysis and detection methods of oxine-copper simultaneously in paddy field by added recovery test, and systematically studied the residue, degradation of oxine-copper after 33.5% oxine-copper SC be applied in the paddy field. Then put forward the reasonable and scientific recommendations on using this drug in paddy field. Besides, Research oxine-copper, copper-abietate, copper calcium sulphate, Pisa grass and copper-hydroxide to aquatic organisms (tadpole and Lemma Paucicostata) toxicity paddy ecological environment, compare the toxicity and mechanism of these five copper pesticides to aquatic organisms. Moreover, we studied physiology and biochemistry of these five copper pesticides to Lemma Paucicostata. The main contents and results were as follows:(1)The residue analysis method of oxine-copper in paddy water, paddy soil, rice plants, paddy rice straw, rice husk, and coarse rice was systematically established by high performance liquid chromatography(HPLC). Paddy water, rice plants, paddy rice straw, rice husk, and coarse rice were extracted with acetonitrile and hydrochloric acid(lmol/L); paddy soil were extracted with acetonitrile and sodium hydroxide(2mol/L). Paddy water need not to be purified, the rest of samples extracts were cleaned up with hexane and acetonitrile, respectively, and determined by HPLC equipped with UV detector, and analyzed quantitatively with external standard method. The recoveries of oxine-copper in coarse rice was 82.84%-108.82%, and the relative standard deviations was 1.84%-4.87% respectively. The minimum detectable amount of oxine-copper was 2.0×10-10g respectively. The analytical methods could comply with the technical requirements for the analysis and detection of pesticide residue.(2) In 2013 year, a field experiment was conducted to reveal the residual dynamics and final residue of oxine-copper after 33.5% oxine-copper SC applied in paddy field in Changsha, Hangzhou and Nanning of China. The results of degradation dynamic test showed that the degradation dynamics of oxine-copper in paddy water, paddy soil and rice plants could meet the requirements of the first-order chemical reaction kinetic equation. The half-life of oxine-copper in paddy water, paddy soil and rice plants were 5.14d～5.38d, 11.63d～16.08d and 4.95d～5.87d respectively. These results showed that oxine-copper are degradable fungicides in paddy field. With the final residue test that the rice plants was sprayed 2 to 3 times with 33.5% oxine-copper SC in the dosage of 301.5 g a.i./ha and 452.25g a.i./ha, each spraying intervals for seven days, the results showed that when the last application was done at 21 days, the maximum residual value of oxine-copper in coarse rice was less than O.Olmg/kg. By the results, we recommended that the rational use of 33.5% oxine-copper SC in paddy field was that 33.5% oxine-copper SC was sprayed in rice with a dose of 900g/ha (the content of effective component:301.5g a.i./ha) for 2 times at most, the safe period of oxine-copper in rice could be set as 21d.(3) Through acute toxicity of copper-abietate, copper-hydroxide, Pisa grass, copper calcium sulphate and oxine-copper to tadpoles. The results showed that the acute toxicity of copper-abietate and copper calcium sulphate to tadpoles was middle toxic, Pisa grass and copper-hydroxide to tadpoles was highly toxic and oxine-copper to tadpoles was the most toxic. The LC50 of 96h were 1.760 mg/L,0.148 mg/L,0.319 mg/L,1.334 mg/L and 0.0046 mg/L. The acute toxicity of these five copper pesticides to tadpoles from high to low was oxine-copper, copper-hydroxide, Pisa grass, copper calcium sulphate, copper-abietate.(4) Through growth and physiological and biochemical effects of copper-abietate, copper-hydroxide, Pisa grass, copper calcium sulphate and oxine-copper to Lemma Paucicostatas. The results showed that the toxicity of copper-abietate and copper calcium sulphate to Lemma Paucicostatas was low toxic, Pisa grass and copper-hydroxide to Lemma Paucicostatas was middle toxic and oxine-copper to Lemma Paucicostatas was highly toxic. The EC50 of 96h were 5.85 mg/L,0.44 mg/L,1.18 mg/L,5.12 mg/L and 0.17 mg/L. we studied the effects of these five copper pesticides on pigment composition and content of Lemma Paucicostata. The results showed that Lemma Paucicostata of pigment could be stimulated increase for low concentration copper pesticides and the high concentration could reduce Lemma Paucicostata of pigment. The toxicity of these five copper pesticides to Lemma Paucicostata was the same to tadpole.