On-line Monitoring Of Emergency Pollution Of Ochratoxin A In Drinking Water And Its Biological Toxicity Assessment

Drinking water safety is crucial to the lives and health of residents and there is a potential threat of human poisoning and sudden pollution due to the complex process from the water supply to residential areas.For the sake of preventing the risk of major drinking water safety accidents,it is urgent to establish the methods including online monitoring and early warning,rapid water toxicity assessment and emergency measures.The potential pollutant of ochratoxin A（OTA）was used as a research target in the thesis.The growth and OTA toxin-producing properties of Aspergillus Ochraceus（A.ochraceus）in different cultures were studied.A new method of flow injection chemiluminescence was established for the online monitoring.The luminescent bacteria assay of Photobacterium leiognathi（P.leiognathi）was built for rapid detection and toxicity assessment of OTA.The effective measures were proposed to deal with the emergency pollution of OTA in drinking water system.The main research results are as follows:1.A.ochraceus is easy to cultivate and produce OTA.Among three different culture plates of PDA,CS and YES,A.ochraceus shows most vigorous growth in YES with its colony diameter of 7.66 cm and its highest OTA production of 24.67ng/mm² after dark culture at 25℃for 8 days.In ground corn,wheat,peanut and rice natural cultures,the most suitable culture for the mass toxin production and mechanism research of OTA is ground wheat medium with its high yield of 50.82μg/g after dark culture at 25℃for 8 days.2.Based on the quenching effect of OTA on chemiluminescence（CL）reaction of Luminol-Na IO₄-Tween 20 system,a novel flow-injection chemiluminescence method was developed for the rapid online determination of possible sudden pollution of OTA in drinking water.Under the optimum conditions of response surface experiment,the linear range for OTA was 0.006～1.000μg/m L with a detection limit of 1.74×10^-3μg/m L and recovery of 80.6%～92.4%.This method was convenient to operate and could be applied to the rapid emergency waring and real-time monitoring of OTA in drinking water.3.A novel technique was developed for rapid monitoring and toxicity assessment of ochratoxin A（OTA）by P.leiognathi based on its inhibition of bioluminescence.A correlation（R²=0.9858）was obtained between the relative luminosity unit of P.leiognathi and OTA concentration in the range of 0.01-20 mg/L with the recoveries of80.8%-87.4%.The IC₅₀ values of 12.71 mg/L at 30 mins demonstrated the good sensitivity of P.leiognathi to OTA.The cells of P.leiognathi under OTA exposure showed morphological alternations,protein damage,apoptosis and necrosis.4.In the physical removal method of OTA,ultraviolent radiation has a better removal effect than incandescent lamp but it is relatively energy-consuming.Ultrasonic waves and diatomite show a poor removal effect of OTA in drinking water while powdered activated carbon（PAC）demonstrates significant OTA removal rate（95.08%）under the optimum conditions of response surface experiment when its adding sample is 0.25 g/L,adsorption temperature is 20℃and adsorption time is 12mins.This method can be applied as a rapid emergency removal method for the sudden pollution of OTA in drinking water.