Evaluation of the Potential Agricultural Risks of Polycyclic Aromatic Hydrocarbon Contaminated Soil by Planting Lactuca sativa L.

Abstract

In order to evaluate the potential agricultural risks of soil contaminated by polycyclic aromatic hydrocarbons (PAHs), Lactuca sativa L. was used as a model leaf vegetable plant to investigate the enrichment characteristics of PAHs in the different tissues of Lactuca sativa L, such as its underground parts (GS) and aboveground parts (YS), which were studied through an experiment involving potted cultivation in PAHs contaminated soil that was taken from the agricultural soil around a coking enterprise area. The concentrations of the different PAHs in the soil and plant tissues were analyzed using ultrasonic oscillation extraction and high-performance liquid chromatography-mass spectrometry (GC-MS) analysis methods. The results show that the enrichment of the total PAHs (Σ16PAHs) in the YS is higher than that in the GS. The components enriched in the YS mainly consist of 3-5 ring PAHs, and those in the GS consist of 4-6ring PAHs. The coefficients of the different PAHs enriched in the YS were higher than those of the GS. The enrichment coefficient of anthracene (Ant) was the largest and that of fluoranthene (Fla) was the smallest in the YS, while the enrichment coefficient of benzene[a]pyre (Bap) was the largest and that of Fla was the smallest in the GS. The transfer coefficients of the different PAHs from the GS to the YS were greater than the rate from the initial soil (SS) to the GS; the value is less than 1 from the SS to GS. The correlations and goodness of fit were analyzed for the concentrations of PAHs in the SS, GS and YS. The Σ16PAHs in the SS showed positive correlations with the Σ16PAHs in the YS and in GS. The goodness of fit of the correlation of the PAHs in YS to those in the SS was the largest (R2=1.0), while the goodness-of-fit for the correlation between the GS and SS was lower (R2=0.71). The benzo[a]pyrene equivalent concentration values (Σ16PAHsBapeq) of YS and GS were 11.8 and 12.7 times the maximum value of Bap level allowed in food. The study indicates that contaminated farmland soil would present a high health risk when it was used to grow the plant.