| Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine, C8H14CIN5) is one of themost widely used herbicides in China and the world. It can enter into water-bodies by theways of surface water runoff, eluviation, dry or wet sedimentations, and so on, influencingdirectly the vascular bundle hydrophytes and phytoplankton and it also producingtoxicological effects on aquatic animals like fishes at the same time. Recently, a great dealof attention has focused on atrazine for its large use, long persistence, high detection ratioin natural water-bodies and endocrine disruption and so on. So it is emergent to evaluatethe water ecological safety of atrazine.Using crucian as test animal, the experiment researched acute toxicity of herbicideatrazine to fishes and effects of low concentration of atrazine on serum estradiol content,antioxidant enzymes activities and micronucleus of erythrocyte and its bioaccttmulationtrend in liver, kidney and muscle at the same time. Concentrations were set as 0, 0.1, 0.5,1.0, 5.0 and 10.0 mg.L-1, respectively, in sub-acute toxicity test. Sample male crucianexposuring to 5.0 mg.L-1 alter days 6, 10, 14, 19 and 24, respectively, to study thetime-effect relationship between atrazine and serum estradiol content; and sample malecrucian exposuring to all the concentrations at the end (24d) of experiment to study thedose-effect relationship between atrazine and serum estradiol content when effects of lowconcentration of atrazine on serum estradiol content in male crucian were researched.Sample crucian exposuring to 1.0 and 10.0 mg.L-1 after days 3, 6, 10, 14, 19, 24,respectively, and sample crucian exposuring to all the concentrations at the end (24d) ofexperiment to study effects of atrazine on antioxidant enzymes in different organs andtissues of crucian. Sample crucian exposuring to all the concentrations after days 3, 6, 10,14, 19, 24, respectively, to researched effects of atrazine on micronucleus in erythrocyteand its bioaccumulation trend in liver, kidney and muscle of crucian. And the resultsshowed that:①24h, 48h and 96h LC50 of atrazine to crucian were 229.33mg.L-1, 146.17 mg.L-1 and 105.94 mg.L-1, respectively. So the safety concentration of atrazine to crucian was 10.594mg.L-1 and, consequently, atrazine was low toxic to fishes.②Accumulation velocity of atrazine in fish body was quick and accumulation stablestate was reached by 19d, but accumulation capacity was low. The biggest and lowestbioconcentration factors (BCF) of atrazine in liver, kidney and muscle existed at the lowest(0.1 mg.L-1) and the highest (10.0 mg.L-1) concentrations, respectively, whenbioaccumulation reached the stable state. The biggest BCF in liver, kidney and muscle were13.08, 11.00 and 6.02, respectively, and the lowest BCF in that above were 5.22, 4.37 and2.94, respectively. Bioaccumulation capacity of fishes to atrazine differed with thedifference of pollutant concentrations in water-bodies, that is to say, BCF was large whenpollutant concentration was low and it was small when pollutant concentration was high. Atthe same time, bioaccumulation capacity of fishes to atrazine differed with the difference oforgans, that is to say, liver＞kidney＞muscle.③Afler 24 days of continues exposure, the synthesis of serum estradiol in male crucianwas induced by atrazine at the low concentrations ranging from 0.1 to 5.0 mg.L-1. Thestrongest inducing effect happened when the concentration of atrazine was 1.0 mg.L-1, andserum estradiol content increased by 84.1％compared with that of the control. However,the synthesis of serum estradiol was inhibited at high concentration of 10.0 mg.L-1. Serumestradiol content in male crucian were higher than that of the control at any effecting timein the experiment that researched the time-response relationship between atrazine andserum estradiol content in male crucian at the exposure concentration of 5.0 mg.L-1, and onthe 14th day, the serum estradiol content increased by 50％compared with that of thecontrol and reached the highest value. Because the change of serum estradiol content couldinfluence the reproductive function of male crucian, so it can be concluded that the malecrucian whose serum estradiol content had changed significantly for the enrichment ofatrazine in body were likely to have reproductive problems to some extent. Althoughatrazine could disrupt synthesis and metabolism of serum estradiol in male crucian, thetime-response or dose-response relationships between serum estradiol contents in malecrucian and effecting time or exposure concentrations of atrazine didn't exist significantly.However, significant changes of serum estradiol content in male crucian illuminated itcould be a sensitive biomarker to estimate environment hormone pollution in water bodies.④Atrazine could make antioxidant enzymes activities in liver, kidney and musclechange significantly. And test results about SOD showed that hepatic and renal SOD activities were inhibited and induced, respectively, at all the atrazine concentrations at theend (24d) of the experiment; and muscular SOD activities were inhibited at lowconcentrations and induced at high concentrations. What is more, there were dose-responserelationships between atrazine and hepatic and renal SOD activities at all theconcentrations and the range from 1.0 to 10.0 mg.L-1, respectively. The time-responserelationship between atrazine and muscular SOD activities existed at the time ranging from14 to 24 days. There were no time-response relationships between atrazine and hepatic orrenal SOD activities at any time the experiment has chose. But during the experiment, SODactivities in the same organ influenced by the two concentrations of 1.0 and 10.0 mg.L-1had changed in the same trend. Test results about CAT showed that CAT activities in liver,kidney and muscle were induced at low concentrations ranged from 0.1 to 1.0 mg.L-1,however, CAT activities of that above were inhibited at high concentrations ranged from5.0 to 10.0 mg.L-1 at the end (24d) of test. Time-response test indicated that CAT activitiesin liver, kidney and muscle were induced strongly at concentration of 0.1 mg.L-1 during theexperiment; and, what is more, the inducement effect increased firstly and then decreasedwith time prolonging, and CAT activities of that above maintained in a level just havingfeeble changes finally. Inducement effect reached the strongest point after 10d, and thebiggest inducement ratios in liver, kidney and muscle were 93.96％, 75.39％and 62.86,respectively. Only in the third day after exposure had the hepatic CAT activity beeninduced, and except it, CAT activities in all organs were inhibited at any other time whenthe exposure concentration of atrazine was 10.0 mg.L-1. Test results about GSTs indicatedthat GSTs activities in liver and muscle were induced when effect time was long (24d), andthe strongest inducible rates were 110.81％and 32.54％, respectively. What is more,dose-response relationships between atrazine and hepatic and muscular GSTs activitiesexisted at the ranges from 0.1 to 5.0 mg.L-1 and from 1.0 to 10.0 mg.L-1, respectively.Renal GSTs activities were inhibited when the exposure time was long (24d), and thestrongest inhibitive rate was 14.42％, and dose-response relationship between atrazine andRenal GSTs activities existed at all the concentrations the experiment has chosen.Time-response relationships between atrazine and GSTs activities in liver and muscleexisted at the time ranging from 6 to 14 days when the fish exposed to atrazineconcentration of 10.0 mg.L-1. There were no time-response relationships between atrazineand any organs at other conditions.⑤Ratios of micronucleus and nucleus anomalies in erythrocyte increased significantly under pollution intimidation of atrazine, and there were dose-response relationships andtime-response relationships between atrazine and ratios of micronucleus and nucleusanomalies in erythrocyte, which meant atrazine had strong genetic damage on aquaticanimals and the degree of genetic damage increased with the increase of atrazineconcentration or pollution intimidation prolongging. The test showed atrazine had potentialmutation effect on aquatic animals.The results showed that atrazine was an herbicide with low toxicity to fish and had lowbioaccumulation factor in fish body. However, it could make fish body produce oxidationpressure and had serum estradiol content in male crucian risen, and it had genetic damageto fish to some extent. At the same time, the significant change of the indexes chosen in theresearch and the dose-reponse or time-response relationships between atrazine and theindexes showed they were likely to become biomarkers to estimate atrazine pollution inwater body.
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