| Polycyclic Aromatic Hydrocarbons (PAHs), a typical Persistent Organic Pollutant (POPs), has obviously harmful effect on human health and environment. It was reported that90%of PAHs entered the soil, which could not only affect soil functioning but also affect crop growth and quality, and distribute various components of the ecosystem by the biological chain, finally could harm human health and the whole ecosystem.To scientifically assess and maintain the environment quality of soil, the criteria for PAHs which affect crop yield and quality must be established. Here, through conducting a pot experiment with the rice and wheat grown in different fluoranthene polluted soils (typic hapludalfs and alluvial soil), we studied fluoranthene (FLA) content in soil, crop accumulation and transmission characteristics, and crop growth and grain quality. Several threshold values of soil fluoranthene concentration were obtained by fitting dose-effect equations, which provided scientific basis for establishing PAHs’soil environmental quality criteria and facilitated evaluating their ecological risks. The main research contents and results were as followed:(1) Rice yield weren’t reduced under the investigated FLA’s concentration range (0～50mg·kg-1), while the growth of rice were promoted by FLA Moreover, protein synthesis was suppressed while fat accumulations were promoted in rice grains by the high level FLA. Consequently, as affected by the high concentration of FLA, ash content was decreased while no substantial effect was observed in starch content. The uptake and enrichment of FLA by rice plant increased with the soil FLA concentrations while its conductivity coefficients expressed an opposite mode. Maturing, degradation and FLA’s effect on rice growth was connected with soil organic matter, soil nutrients and CEC of typic hapludalfs and alluvial soil.(2) Across all the testing concentrations in this design (0～100mg·kg-1), no inhibiting effect was found of FLA on wheat grain yield. In contrary, the grain yield was promoted by FLA in our experiment. The accumulation of FLA in wheat plant expressed a positive correlation with soil FLA concentrations. The concentrations of FLA in wheat plant trend expressed as root> grain>stem and leaves. The enrichment coefficient in wheat plant decreased while concentrations of FLA in soil increased. The delivery of FLA from root to stems and leaves was increased inhibited by the concentration increase of FLA in soil.Accumulation of fat in wheat grain was inhibited by FLA while high concentration decreased the ash content of wheat grain. However, no substantial effect was detected in wheat grain protein and starch contents. The maturing, degradation and effect of FLA on wheat was connected with soil physical and chemical property. Compared with flooded rice, wheat cultivation in dry land favors the degradation of FLA in soil.(3) By fitting model between "concentration-effects", relationship of FLA concentrations in contaminated soil and rice, wheat yield as well as the grain quality was analyzed. The critical value of FLA was calculated by a10%decrease in rice or wheat grain quality. Our results showed that, critical value of typic hapludalfs was1.890mg·kg-1while rice root biomass decreased by10%. For a10%decrease in rice grain protein contents, the critical value of typic hapludalfs and alluvial soil and moisture soil was7.337mg·kg-1and1.690mg·kg-1, respectively.Meanwhile, a10%decrease in wheat grain fat concentration occurred while the critical value was3.726mg·kg-1and0.446mg·kg-1for typic hapludalfs a and alluvial soil and moisture soil, respectively. |
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