[Application of automated identification and quantification system with a database (AIQS-DB) to screen organic pollutants in surface waters from Yellow River and Yangtze River].

Approximately 1 000 chemicals were screened in surface waters from downstreams of Yellow River and Yangtze River using GC-MS coupled with Automated Identification and Quantification System with a Database (AIQS-DB). 95 pollutants were detected in water samples from Yellow River in Shandong Province and 121 in those from Yangtze River in Jiangsu Province. The pollutants involved n-alkanes, PAHs, phenols, nitro compounds, phthalates esters (PAEs), pesticides and pharmaceuticals, etc. The average concentrations of n-alkanes, 16 priority PAHs and 6 priority PAEs were 1 806 ng/L, 27 ng/L, 77 ng/L in water samples from Yellow River and 720 ng/L, 30 ng/L, 2 166 ng/L in water samples from Yangtze River respectively. Besides, 9 and 11 pesticides were detected in water samples from Yellow River and Yangtze River respectively. The levels of pollutants showed stronger site dependence in samples from Yellow River than those from Yangtze River. Combination of GC-MS and AIQS-DB shows high efficiency in regional pollutants survey.

[Enhanced sorption of OTC on clays via complexation with Zn2+].

Oxytetracycline (OTC) and Zn2+ are both widely used as growth promoters in concentrated animal feeding operations, which are discharged into soil system by manure application. There is special environment significance to study the sorption and interaction of OTC with accompanied metal cations on clays to elucidate their environmental behaviors and to assess ecological risks. Much stronger sorption of OTC was observed on montmorillonite than that on kaolinite, which might be resulted from the larger cation exchange capacity of the former. Different pH-dependent Kd patterns were illustrated on montmorillonite and kaolinite, which might be contributed by the different properties of surface charge. During 4 < pH < 5, OTC sorption was decreased by cation competition of Zn2+, while OTC sorption was promoted by OTC-Zn-clay bridge while 5 < pH < 9, and the most significant effect was shown at pH = 6.5. The sorption of Zn2+ on two clays was decreased by OTC in the pH range studied, which can be explained by cation competition of OTC at lower pH, or by prohibition in the sorption or precipitation resulted from complexation between OTC and Zn2+ at higher pH. CD and UV-Vis spectrometry analysis showed that there was no complexation observed between OTC and Zn2+ at pH = 4. But with increasing of pH value, complexation might happen at the sites of O11, O12 or O12, O1.

[Prediction of common buffer catalysis in hydrolysis of fenchlorazole-ethyl].

The purpose of this study was to elucidate the effects of temperatures, pH levels and buffer catalysis on the hydrolysis of FCE. The hydrolysis of FCE follows first-order kinetics at different pH levels and temperatures. FCE hydrolysis rates are greatly increased at elevated pH levels and temperatures. The maximum contribution of buffer catalysis to the hydrolysis of FCE was assessed based on application of the Bronsted equations for general acid-base catalysis. The results suggest that the buffer solutions play an obvious catalysis role in hydrolysis of FCE and the hydrolysis rates of FCE are quickened by the buffer solutions. Besides, the buffer catalysis capacity of different buffer solutions is diverse, and the buffer catalysis capacity at different pH levels with the same buffer solutions is different, too. The phosphate buffer at pH = 7 shows the maximal buffer catalysis capacity. The hydrolysis rate constants of FCE as a function of temperature and pH, which were remedied by the buffer catalysis factor, were mathematically combined to predict the hydrolytic dissipation of FCE. The equation suggests that the hydrolysis half-lives of FCE ranged from 7 d to 790 d. Hydrolysis metabolites of FCE were identified by liquid chromatography-mass spectrometry. In basic conditions (pH 8-10), fenchlorazole was formed via breakdown of the ester bond of the safener.

[Influential factors and degradation pathway of imidacloprid by homogeneous Co/PMS system].

Cobaltous-mediated decomposition of peroxymonosulfate (Co/PMS) system is one of novel advanced oxidation technologies (AOTs), which leads to the formation of very strong oxidizing species in aqueous phase. Effects of PMS concentrations, Co2+ concentrations and various inorganic anions (H2PO4-, HCO3-, NO3-, Cl-) on the degradation of Imidacloprid induced by Co/PMS system was investigated as emphasis. The degradation kinetics of imidacloprid followed pseudo first-order kinetics and reaction rates related to PMS and Co2+, concentrations. The reaction rates increased with increasing [PMS] and [Co2+] when the other parameters were constant. However, the decrease of degradation rates was found when the molar ratio of PMS versus imidacloprid was over 20. The effects of H2PO4- had positive effect on the degradation of Imidacloprid, low concentration HCO3- had positive effect and high concentration HCO3- had negative effect, Cl- had negative effect, while NO3- had little effect. Based on the results of GC/MS, two main intermediates were identified, 6-chloronicotinic acid and 6-chloronicotinamide, and the reaction pathway for SO4*- induced by homogeneous Co/PMS was proposed accordingly.