Study On Degradation And Transport Of Sulfadiazine In Soil

Sulfadiazine, chemical name: N-2-pyrimidinyl-4-aminobenzene sulfonamide, w hich is used to preparation for its prevention and therapy in advance infectious diseases which were caused by bacteria, is one of the most amount veterinary drugs. People have proved it harm for human. Therefore, it is very emergent a nd important to comprehensively understand persistence, movement and transfer mation of sulfadiazine and its potential hazards in ecological environments.The investigation, made sulfadiazine as the object and the different soils text ure as environmental medium, study the transport and degradation of sulfadiazi ne in soils and influencing factors. According to the research contents, the diss ertation was divided into five parts. The main conclusions obtained were listed as follows:In the first part the basic concepts, theories and current advances were revie wed briefly on behavior in environment, influence for entironment, transport an d degradation of veterinary drugs, and sulfadiazine characteristic. The content a nd intention of study were mentioned.In the second part a method of UV spectrophotometer was used to determin e the concentration of sulfadiazine in soil and water by using sodium hydroxid e solution as extractant. The results showed: (1) By this method the analytical data, with better accuracy and precision, were obtained by determine sulfadiazi ne in soil and water. The method had many advantages, such as convenience, speed, and accurate. (2) By using 0.1mol/l sodium hydroxide solution as extrac tant, results showed that the linear range of standard carve was 2~10μg/mL an d the correlation coefficient was 0.9999, and the average recovery for soil and water samples were 98.0—101.0% and 94.2～111.50%, respectively, and RSD were 1.36～3.06% and 0.25～2.06%, respectively.In the third part leaching experiment of dynamic soil column was conducted tostudy the transport of sulfadiazine in soils. Results showed that sulfadiazine s howed different ability to be transported downward with moving water in three kinds of soil columns. In sandy soil column, the motion of sulfadiazine wasob vious, and about 70.16% of the added sulfadiazine could be moved out of col umn (40cm) leached continuously by 48L distilled water, 39.66% and 51.12% i n loam column and clay column under the same condition, respectively. The tr ansportation sequence of sulfadiazine in the tested soils was sand > clay > loa m. In addition, the most of sulfadiazine moved out of column was in the halfc ourse of leaching, and the sulfadiazine detained in column distributed mainly i n 0～20cm of soil layer after leaching. So, these results indicated that the mobi lity of sulfadiazine in soils is directly related to the properties of soils. Soil te xture and soil organic matter content are two important influencing factors. In the fourth part indoor simulation experiment of degradation was conductedtostudy the degradation in soils. The results showed: (1) Sulfadiazine was diffi cultly degraded in three kinds of tested soils in the experimental condition. Th e degradation rate of sulfadiazine in the tested soils was sand > loam > clay, and the degradation rate coefficient were 0.0083,0.0066 and 0.00361 with its half-life of 83.5,105.0 and 192.5d, respectively. (2) Sulfadiazine that were add ed different concentrations showed different ability to be degradation in this soi 1 (zhengzhou sand). Degradation of sulfadiazine in soils speeded down with the increasing concentrations of sulfadiazine, in the range of 10～250 mg/kg in soils.The half-life from untreated control samples fortified with 10 mg/kg that wa sthe lowest concentrations was 61.3d, and one was 239.1d with 250mg/kg that was the highest concentrations. (3) Degradation rate coefficient (k) of sulfadiazi ne in sterilized and non-sterilized soil (zhengzhou sand) was 0.0083和0.0070,de gradation half-life was 83.5d and 99.0d, respectively, indicating that microorgan isms would not accelerate the degradation of sulfadiazine in soils. The biodegr adation amount of sulfadiazine was not increased form the tenth, indicating con centration beyond the tolerant of microorganism in soil, and microorganism wer e controlled powerfully by sulfadiazine.In the last part a summary was done on the research results, and meanwhile projects that need to be further studied were suggested.