多环芳烃(PAHs)是持久性有机污染物(POP)之一, 通过大气沉降和污水灌溉能被植物吸收, 对食品生产安全和人类生命健康具有极大威胁。为探究PAHs对蔬菜作物的生长影响及毒害机理, 采用盆栽试验研究了不同浓度的荧蒽(FLU)和苯并[a]芘(B[a]P)单独胁迫下对油菜(Brassica chinensis)生长、生理和品质的影响及在油菜茎叶内的积累。结果表明: FLU和B[a]P在油菜茎叶内的积累量随着土壤中施加浓度的升高而增加, FLU胁迫下各处理间差异显著(p < 0.05), B[a]P胁迫下5.0和10.0 mg·kg^-1时积累量与对照(CK)相比显著(p < 0.05)增加, 10.0 mg·kg^-1时油菜茎叶内的最大B[a]P积累量没有超过我国食品安全标准; FLU和B[a]P对油菜叶长、叶宽和地上生物量的影响都是低浓度促进高浓度抑制; FLU和B[a]P胁迫下与CK相比株高和光合速率(P_n)值都显著(p < 0.05)降低; 对叶绿素含量的影响是低浓度促进高浓度抑制; 从总体来看, FLU胁迫对还原性维生素C (Vc)具有抑制作用, 5.0 mg·kg^-1时Vc含量最低, 而B[a]P胁迫下变化不规律, 在0.5 mg·kg^-1胁迫时与CK相比略有增加, 5.0 mg·kg^-1时含量最低。

Aims Polycyclic aromatic hydrocarbons (PAHs) are a large class of ubiquitously occurring persistent organic pollutants (POP). Plants can take up PAHs through atmospheric sedimentation and sewage irrigation, resulting in serious hazards on the food safety and human’s health. Our objective was to investigate the effects of fluoranthene (FLU) and benzo-a-pyrene (B[a]P) on growth, physiological performance, and quality of rape (Brassica chinensis), and to understand their patterns of accumulations in stem and leaves.
Methods Rape seedlings were transplanted to grow in soils with different rates of FLU and B[a]P addition, i.e. 0, 0.5, 1.0, 5.0, and 10.0 mg·kg^-1, respectively. Growth indicators including leaf length, leaf width, plant height and aboveground biomass, and physiological properties including photosynthetic rate (P_n), chlorophyll content, and the content of vitamin C were measured to determine the effects of the two PAHs on rape. Accumulations of FLU and B[a]P were measured by the method of high performance liquid chromatography (HPLC). Pearson correlation analysis was performed to investigate the relationships between the accumulations of the PAHs and various growth indicators.
Important findings We found that the accumulated concentrations of FLU and B[a]P in rapes increased with the level of FLU and B[a]P in soils. The accumulations of FLU in stems and leaves differed significantly (p < 0.05) among treatments with different rates of FLU addition. As compared with the control (CK), the accumulations of B[a]P in rapes significantly increased in treatments with 5.0 and 10.0 mg·kg^-1 B[a]P addition, and the highest amount of accumulation at 10 mg·kg^-1 was below the national food security standard. Low concentrations of FLU and B[a]P had positive effects on leaf length, leaf width and the aboveground biomass; whereas high concentrations had negative impacts. As compared with CK, plant height and P_n significantly decreased with of the level of FLU and B[a]P treatments. Chlorophyll content increased at lower concentrations but declined at higher concentrations. Overall, the reduced vitamin C was inhibited by FLU; it was lowest at 5.0 mg·kg^-1 of FLU. The reduced vitamin C varied irregularly with B[a]P treatments; it increased slightly at 0.5 mg·kg^-1of B[a]P and was lowest at 5.0 mg·kg^-1 of B[a]P, compared with CK.