Abstract: In order to investigate the soil quality in non-polluted food bases in Nanjing,a total of 70 soil samples were collected from the surface soil layer in Baguazhou,Nanjing for analysis of residues of organochlorine pesticides(OCPs)(α-,β-,γ-,and δ-HCH,o,p′-DDT,p,p′-DDT,o,p′-DDE,p,p′-DDE,and p,p′-DDD) and their characteristics.OCPs were extracted by ASE(accelerated solvent extractor) with acetone/petroleum ether(1/4,V/V),cleaned up with silica gel column and quantified by capillary gas chromatography with a 63Ni electron capture detector(GC-μECD).Results show that total OCPs residues in the soils ranged between 6.18 and 84.72 μg·kg^-1,averaging 18.63 μg·kg^-1.The concentration of DDT was much higher than that of HCH in soils.DDT residues ranged from 3.36 to 74.19 μg·kg^-1 with an average being 12.61 μg·kg^-1,while HCH residue did from 2.48 to 17.80 μg·kg^-1 with an average being 6.02 μg·kg^-1.Both DDT and HCH in all the soil samples were far below the threshold value of 500 μg·kg^-1 in the Chinese "Non-Polluted Food Base Soil Quality Standards".However,most of them were much higher than the criteria for non-polluted soils in the "Guideline for Soil Protection of the Netherlands".

Key words: DDT, HCH, organo-chlorinated pesticide, non-polluted food base, residue