高氟病区茶园土壤氟形态及其分布特征

采用连续化学提取法,测定了黔西北高氟病区茶园土壤样品氟含量及氟的形态.结果表明:供试土壤全氟含量为314~3558mg/kg,平均为945mg/kg,高于全国土壤全氟平均含量(453mg/kg).不同类型供试土壤中全氟含量高低顺序为:棕壤和褐土(分别为1118和1114mg/kg)>黄棕壤(908mg/kg)>黄壤(681mg/kg).供试土壤中不同形态氟含量以残余态最高,其平均含量为940mg/kg;其次为有机束缚态氟,平均含量为7.82mg/kg,处于氟污染较高水平,可能会对人体健康和生态环境产生重要影响;铁锰结合态氟也较高,平均含量3.99mg/kg;水溶态氟和可交换态氟均较低,其平均含量分别为:1.98,1.14mg/kg.由此可见,土壤中氟形态大部分均以残余态形式存在于土壤中,可被茶树叶吸收的水溶态氟和可交换态氟含量均不高.相关性分析表明:可交换态氟只与水溶态氟呈显著正相关关系(r=0.459**),而水溶态氟与铁锰结合态氟、残余态氟和全氟均呈正相关关系(r分别为0.240*, 0.226*, 0.229*), 有机束缚态氟与铁锰结合态氟、残余态氟和全氟也呈正相关关系(r分别为0.757**, 0.312**, 0.320**),水溶态氟与土壤交换性盐基含量之间也呈极显著正相关关系,而土壤氟形态与有机质的相关性不明显,仅有机束缚态氟与土壤有机质呈弱负相关.本研究可为该区域土壤氟污染防治提供科学依据,也为土壤氟的迁移转化及其对生态和环境的影响研究奠定一定的理论基础.

Distribution characteristics and speciation of fluorine in tea Garden soils in the high fluoride area

The objectives of this article were to study fluorine speciation and its distribution characteristics in tea garden soils in the high fluoride area. The fluorine content and speciation in tea garden soils of northwest Guizhou were measured by consecutive extraction. The results showed that the soil total fluorine (T-F) content ranged from 314 to 3558mg/kg, with a mean of 945mg/kg, which was much higher than the natloncal mean of 453 mg/kg. The content of total fluoride in the collected soils were decreased in the order: brown soils and tan soils (with mean values of 1118mg/kg and 1114mg/kg) > yellowish-brown soils (with a mean value of 908mg/kg) > yellow soils (with a mean value of 681mg/kg). Residual fluorine (Res-F) was the highest among different fluorine forms, with a mean of 940mg/kg. The organic-fluorine (Or-F) was also an important part, with a mean of 7.82mg/kg. The result indicated that soils in the studied area were at a relatively high fluoride pollution level, which may be harmful to human health and ecological environment. The content of Fe/Mn oxide-fluorine (Fe/Mn-F) was also high, with a mean of 3.99mg/kg. The content of water soluble fluorine (Ws-F) and exchangeable fluorine (Ex-F) were relatively low, and their average value was 1.98 mg/kg and 1.14 mg/kg respectively. Therefore, fluorine in the collected soils mainly existed as Or-F, and Ws-F and Ex-F which could be hardly absorbed by tea leaves. Correlation analysis showed that Ex-F was significantly correlated with Ws-F (r = 0.459**), Ws-F was correlated with Fe/Mn-F, Re-F and T-F (r =0.240*, 0.226*, 0.229*), and Or-F was correlated with Fe/Mn-F, Re-F and T-F (r=0.757**, 0.312**, 0.320**). In addition, significant correlation was found between Ws-F and content of exchangeable salt. However, no significant correlation was found between fluorine forms and soil organic matter with theexception of a weak negative correlation existed between Or-F and soil organic matter. The study provided scientific evidences for protection and restoration of fluorine polluted soils, and offered theoretical knowledge about migration and transformation of soil fluorine and their influence on ecology and environment.