| Pesticide is one kind of necessary means of production in agriculture. However, it is a harmful chemical substance. It will do harm to people's health and ecological environment owing to its unreasonable application. Pesticide aniline and pentachlorophenol (PCP) are extensively applied all over the China, but some important environment behaviors of them such as microbial degradation, degradation mechanism and bioaccumulation characteristics et al. have not been reported until now. In order to comprehensively evaluate environmental risk of aniline and pentachlorophenol, the biodegradation and adsorption of aniline and pentachlorophenol by two species of typical fresh algae and three kinds of plants were studied respectively. The main conclusions obtained are listed as follows:Firstly, an analytical method for determining residues of aniline in medium and algae cells by HPLC was established.The recovery rates ranged from 79.0% to 95.1% and RSD varied between 0.1% and 0.9%.The accuracy, sensitivity, precision for the method was satisfied to meet the quota requirements of pesticide residue.Secondly, the biodegradation and bioaccumulation of aniline by the green algae Chamydomonas reinhardtii, at the fortification level of 10 mg/L, were investigated. The bioaccumulation and adsorption by algae after treatment in the control CHU-11 medium was 1.2% .The removal of aniline over an 8-day period in the control medium and with the group of ABT was 32% and 35%, respectively. With algae culture the removal of aniline was 56%. About up to 24% of total aniline was biodegraded or biotransformed by C. reinhardii in 8 days. C. reinhardii biotransformed aniline into acetylaminobenzene and the cytochrome P-450 was the key enzyme in the metabolic pathway.The biodegradation and bioaccumulation by the algae, Euglena gracilis, under autotrophic and heterotrophic conditions upon exposure to 10 mg/L condition of aniline were investigated. Results showed that over an 8 day period about 17% and 6% of aniline were degraded by light and by Euglena gracilis under autotrophic conditions, respectively. About 5% and 52% of aniline were degraded by vaporization and by Euglena gracilis under the heterotrophic condition, respectively. The removal rate of aniline over an 8 day period with the group of ABT was 19% and 34% under autotrophic and heterotrophic conditions. About 0.6% and 3% of the aniline were accumulated by algae cells under the former two conditions. Additionally, irrespective of what kind of conditions, the degradation products were acetylaminobenzene.Thirdly, a method for determining residues of the persistent organic pollutants (POPS) pentachlorophenol in environment was founded by means of GC-μECD. Samples were extracted with petroleum ether and dilute sulphuric acid about 90 minutes by means of vibrating, and re-extracted with sodium carbonate, derivated with acetic anhydride about 20 minutes under the condition of pH 9 and at the same time extracted, finally analyzed by GC-μECD. The recovery rates ranged from 81.7% to 99.4% and RSD varied between 1.05% and 4.53%. Generally speaking, the method was simple, sensitive, stable, quick and can be used as a routine method for determination of trace PCP in environment.Fourthly, the use of plants to detoxify contaminated soil or groundwater is a potentially cost-effective alternative to traditional remediation technologies. The different plants ability of bioaccumulation and biodegradation of PCP from soil were investigated. The initial concentration of PCP was 2000.00μg/kg, at the end of the experiment after 30 days, chinese shallot (Scirpus tabernaemontani Gmel)absorbed most PCP, cattail(Typha orientalis Presl) absorbed more and reed (Phragmites communis (L.) Trin) absorbed lest from the soil. Generally speaking, it is a feasible technology to utilizing plants enhances the degradation of organic contaminants such as PCP in soil systems.Finally, phytoremediation is a cost-effective method to detoxify the contaminated soil by organic matter. In this paper, the ability of Chinese shallot to bioaccumulate PCP from soil was investigated. When the initial fortification concentration was 2000.00μg/kg in soil, the recovered residues of PCP in shallot-planted soil only accounted for 28.34% and 1.03%, respectively, of the initial level at 30 and 60 days after treatment (DAT). Almost complete disappearance (＞99.00%) was noticed after 90 days. In contrast, the concentrations of PCP for shallot-unplanted treatment represented 95.09, 81.17, 71.32, and 63.75%, respectively, of the initial level at 30, 60, 90, and 120 DAT. The data fitting results showed that time-trend of PCP could be well described by the first-order kinetic equation in both shallot-planted and unplanted treatment, and the correspondingly estimated half-lives were 11.83 and 173.25 days, respectively. The disappearance in shallot-planted soil approximately increased 15 times over that in unplanted soil. In addition, it was also monitored that PCP residue (579.55μg/kg) in shallot root at the beginning of the experiment increased to its maximum amount (2090.00μg/kg) at 30 DAT. The preceding results proved that shallot had a high bioaccumulation capacity for PCP. Therefore, it can be concluded that shallot is a good alternative plant to remediate PCP-polluted soil or sediment in water system.
|
PDF Full Text Request