赤壁市茶园土壤多环芳烃季节分布的特征分析

Seasonal distribution of polycyclic aromatic hydrocarbons in the soil of tea plantations in Chibi County

土壤是持久性有机污染物多环芳烃(PAHs)的主要归趋之一,城市、农业、工业等土壤中PAHs浓度水平、污染来源及风险评估等研究得到了广泛的关注。采用气相色谱质谱联用法对赤壁市太平口村茶园土壤PAHs的分布、来源及生态风险评价进行了季节差异分析。结果表明:茶园土壤中16种PAHs的总浓度为18.38~154.44 ng·g^(-1),平均值71.33 ng·g^(-1);夏季土壤中PAHs浓度略高于冬季。整体上茶园土壤中PAHs是以5~6环组成为主,但在冬季有25%样点是以2~3环为主。通过源解析发现,赤壁市茶园土壤PAHs主要来自石油燃烧,木材及煤炭燃烧等混合燃烧源。其中冬季土壤PAHs还存在石油输入源。茶园土壤中总有机碳(TOC)与总PAHs存在显著的相关性(r^(2)=0.46,p≤0.05),其中与高环PAHs之间存在显著相关性(r^(2)=0.5,p≤0.01),与低环PAHs不存在相关性(r^(2)=0.13,p≥0.05)。生态风险评价结果表示,尽管赤壁市茶园土壤PAHs整体生态风险相对较低,但也存在一定致癌风险,其中以苯并(b)荧蒽(BbF)、二苯并(a,h)蒽(DahA)和茚并(1,2,3-cd)芘(InP)的毒性当量浓度贡献最大。

Soil is one of the main places for accumulation of persistent organic pollutants,such as polycyclic aromatic hydrocarbons(PAHs).PAHs concentration,sources and risk assessment in urban,agricultural and industrial soils have received extensive attention.Seasonal differences in the distribution,sources,and ecological risk assessment of PAHs in the soil of the tea plantations in Taipingkou Village,Chibi County were analyzed using gas chromatography-mass spectrometry.The findings showed that the total concentration of 16 PAHs in the soil of tea plantations was in the range of 18.38~154.44 ng·g^(-1),with an average of 71.33 ng·g^(-1);the PAH concentration was slightly higher in summer than in winter.Overall,five or six ring PAHs were predominant in tea plantation soil,but in winter,25%of sampling points were dominated by 2-3 ring PAHs.Source analysis revealed that PAHs in the tea plantation soil in Chibi County mainly came from petroleum combustion,mixed combustion sources such as wood and coal.Additionally,in winter,there was also a petroleum input source for PAHs in the soil.There was a significant correlation between total organic carbon(TOC)and total PAHs in the tea plantation soil(r^(2)=0.46,p≤0.05),with a significant correlation between high-ring PAHs(r^(2)=0.5,p≤0.01),and no correlation with low-ring PAHs(r^(2)=0.13,p≥0.05).The ecological risk assessment results indicate that although the overall ecological risk of PAHs in the soil of tea plantations in Chibi County is relatively low,there is still a certain carcinogenic risk,with benzo(b)fluoranthene(BbF),dibenzo(a,h)anthracene(DahA),and indeno(1,2,3-cd)pyrene(InP)contributing the most to the toxicity-equivalence concentrations.