基于DGT技术对土壤硒生物有效性及其影响因素的分析

硒是生态环境中重要的微量元素之一,如何准确评估其生物有效性一直存在争议。在四川省广安市邻水县采集了60套农作物及其根系土样品,分析其Se含量和理化性质。同时基于梯度扩散膜技术对土壤有效Se含量进行分析,并对土壤有效Se含量的影响因素进行探究。结果表明,研究区土壤Se含量为0.15~2.42 mg/kg,均值为0.48 mg/kg,不同类型土壤Se含量差异明显,石灰土(1.06 mg/kg)>黄壤(0.78 mg/kg)>紫色土(0.28 mg/kg)>水稻土(0.27 mg/kg)。石灰土和黄壤有机质含量和总铁(TFe₂O₃)含量明显高于其他类型土壤。研究区内不同类型土壤的DGT-Se明显不同,与土壤Se含量分布相反。相关性分析表明土壤DGT-Se与Se含量、TFe₂O₃含量、S含量、有机质含量、pH值、Al₂O₃含量显著相关,受理化性质影响导致不同类型土壤中DGT-Se的差异。水稻根系土壤DGT-Se与水稻籽实Se含量显著正相关,用DGT可以较好地表达水稻-根系土系统中土壤Se的生物有效性。基于DGT技术评估预测区域尺度农业土壤有效Se含量时,需充分考虑土壤类型及其理化性质。

Analysis of Soil Selenium Bioavailability and Its Influencing Factors Based on DGT Technology

Se is one of the important trace elements in the environment, and the accurate evaluation of its bioavailability has always been controversial. Sixty sets of crop and root soil samples were collected in Linshui County, Guang’an City, Sichuan Province, and the Se content, physical properties, and chemical properties of crops and soil were analyzed. Results showed that the total Se content in the soil of the study area ranged from 0.15 mg/kg to 2.42 mg/kg (average=0.48 mg/kg). The total Se content of the different types of soil in the study area was considerably different and followed the order: lime soil (1.06 mg/kg)>yellow soil (0.78 mg/kg)>purple soil (0.28 mg/kg)>paddy soil (0.27 mg/kg). The organic matter and the total Fe₂O₃ (TFe₂O₃) contents of the lime and the yellow soil samples were remarkably higher than those of the other types of soil. The content of the DGT-Se in the different types of soil in the study area was evidently different. The correlation analysis showed that the soil DGT-Se was significantly related to the total Se, TFe₂O₃, S, organic matter, and Al₂O₃ contents and pH of the soil (p<0.01). The influence of its physical and chemical properties led to differences in the DGT-Se in the different types of the soil. The content of the DGT-Se in the soil of rice roots was significantly positively correlated with the Se content in rice seeds (r=0.55, n=29, p<0.01). The DGT could be used as an indicator for the bioavailability of the soil Se in the rice-root soil system. The type, physical properties, and chemical properties of the soil should be fully considered in the evaluation and the prediction of the available Se content of agricultural soils on a regional scale on the basis of the DGT technology.