| Phenols are divided into two categories. One kind is votile phenol which boiling point is below 230℃, the other is non-volatile phenol with the boiling point above 230℃. Phenols in water mainly are from the waste water of the industry of oil refining coking, coking plant, gas washing, papermaking, synthetic ammonia, wood preservative and chemical engineering. Phenols have a great harm on the environment and human beings. When phenol concentration is between 0.1 mg/L and 0.2mg/L, fish smells; greater than 5mg/L, fish poisons and dies. Toxicity of phenols has its main features:they are genotoxic, carcinogenic and immunotoxic. This is mainly because phenols can provide carcinogenic free radicals, and there are some phenols are considered as reactive oxygen species generating agents. Firstly a kind of method was studied in this paper to detect the contents of phenols in surface water and freshwater fish of Wuhan, and then the effects of phenols on physiological indicators of Carassius auratus were studied, and finally the degradation of phenols was studied.1 Detection of phenols in water and fishTraditionally, steam distillation/4-aminoantipyrine(4-AAP) method was used to detect the phenols in environment. However, this method is time-consuming and energy-consuming. Therefore, this study adopted direct distillation instead of steam distillation, distilled water instead of phenol-free water to detect phenols in water and fish. The linear range was 0.0003mg/L-6mg/L, with detection limit 0.0075mg/kg, and the recovery was 98.4%-107.0% by this method. This method was simple, and it had faster detection speed than the steam distillation method, suitable for promotion.This method was used to detect the volatile phenol content of common freshwater fish in the markets and the surface water of Wuhan. The results showed that the surface water and freshwater fish in Wuhan had been polluted by volatile phenols. Detection of the surface water of Wuhan showed that, compared with riners in Wuhan, the pollution of volatile phenols in lakes in Wuhan was more serious, and the volatile phenol content in the area along banks of rivers or lakes was higher than that in the middle area of rivers or lakes, up to 0.009mg/L, far beyond the fishery standard (0.005mg/L). Erythroculter ilishaeformis had the highest volatile phenol content among common freshwater fishes in the market of Wuhan up to 0.213mg/kg, beyond the fishery standard (0.2mg/kg).2 Effect of phenols on physiological indicators of Carassius auratusIn this experiment, Carassius auratus as experimental object,4 kinds of water system by different phenol concentration (0,0.15,1,2mg/L) was designed to feed carp. Nutrition, flavor and peroxide value of the crucian carp were measured periodically to study the effects of phenols on physiological indicators of Carassius auratus.The changes of the water and ash content in Carassius auratus muscle had the same trend with phenol concentration and drug exposure time, increased significantly (P<0.05) in the first week, and then decreased significantly (P<0.05). The fat content in Carassius auratus muscle decreased significantly (P<0.01)in the first week, then increased significantly (P<0.01). The protein (crude protein, salt-soluble protein and soluble protein) content in Carassius auratus muscle decreased significantly (P<0.01 or P<0.05) with phenol concentration and drug exposure time. but it could increase fat content, and made crude protein, salt-soluble protein and soluble protein decreased. The presence of phenol in water caused the changes of fatty acids. It would make the polyunsaturated fatty acids' relative content decreased significantly (P<0.01 or P<0.05). So that, monounsaturated fatty facids and saturated fatty acids increased relatively. That maight be due to that votatile phenols could result in lipid oxidation in Carassius auratus muscle. In addition, volatile phenols could significantly (P<0.01 or P<0.05) affect texture properties of crucian carp's back muscle, making its hardness, elasticity, chewiness and cohesiveness decreased.SOD activity in the liver of Carassius auratus had been inhibited significantly (P<0.01 or P<0.05) with the effects of phenols, and when the votatile phenols content was up to 1.Omg/L, this inhibition increased following the concentration of phenols and time. However, this change relation was not such obvious on GSH-PX activity and CAT activity in the liver of Carassius auratus. In addition, with the effects of volatile phenols, SOD and GSH-PX activity in the liver of Carassius auratus in low concentration (0.15mg/L) of votatile phenols rised transitorily, which might because SOD and GSH-PX were inducible enzymes. When the concentration of phenols were below a certain point, the enzyme's activity was inducted, resulting in a short period of increase of the enzyme's activity in the protophase. In this study, crucian carp was used as the experimental animal, phenols make SOD, GSH-PX and CAT activity in the liver of crucian carp decreased was discovered for the first time, which indirectly confirmed the previous report about phenols were genotoxic, carcinogenic and immunotoxic.The presence of phenols in water could make content of IMP in carp muscle decreased significantly (P<0.01). With the phenol concentration increasing, compared with the control group, the volatile esters in Carassius auratus muscle continued to decrease, and some kinds of aldehydes which produced off-odor rised. This might be due to that the presence of volatile phenols could damage the crucian carp's oxidation system, so the fatty acids oxidated and produced short chain aldehydes with off-odor.3 The degradation of phenol in waterSince phenols could made such toxic effects on fish, it was imperative to explore a kind of energy efficient, low-power method to degradate phenols in water. In this study, TiO2/Fe2O3 as the composite catalyst, H2O2 as oxidant were used to ultrasonic degradation of phenol, with the highest degradation rate of 69.8%. |
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