A detection method for organophosphorus pesticides using electrochemical sensor based on enzyme inhibition has been developed. Acetylcholine esterase (AChE) was selected to quantify the pesticides concentration in water samples due to its activity was non-competitively inhibited in the presence of pesticides. To detect parathion and dichlorvos, optimized analytical conditions were that the substrate concentration was 3mmol/L, enzyme solution concentration was 18g/L and reaction time was 20min. Under the optimized detection conditons, a detection limit of 1.2ng/mL and 0.004ng/mL for parathion and dichlorvos was obtained, respectively. The approach was rapid, simple, accurate and of high sensitivity when compared with immunoassays or chromatographic methods.
Decontamination level and residual amount of polycyclic aromatic hydrocarbons (PAHs) were investigated by ex-situ remediation technologies including biopile, soil washing and thermal desorption in a field level. After the remediation, 16 USEPA priority PAHs were decontaminated from 99.3% to 99.9% for thermal desorption, from 17.9% to 82.1% for biopile and from-27.6% to 84.3% for soil washing. Residual PAHs amount in soils by thermal desorption was below the local soil screening level, differently from that by biopile and soil washing. Especially for high molecular weight PAHs, i.e. 5-6 rings PAHs, residual amount exceeded over the screening lever 4 to 197 times for biopile and 17 to 421 times for soil washing. Additional factors, such as cost, time, operation and maintainance etc. for remedial technology selection and contaminant bioavailability in soil matrix for remediation target values, were proposed to be paid more attention for specific contaminated sites.
This is the report describing the biodegradation of benzo[a]pyrene (BaP) by strains isolated from the soil of the PAH contaminated sites. Achromobacter sp and Alcaligenes sp were found with the capability of degrading Bap as sole carbon source, their biodegradation performance of BaP was evaluated when the initial BaP concentrations was approximately 0.25mg/L, 0.40mg/L and 0.90mg/L. The results demonstrated Alcaligenes sp could degrade Bap completely within two weeks when the initial Bap concentration was 0.40mg/L. Alcaligenes sp showed higher removal efficiency than Achromobacter sp.
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