大气O_3浓度升高对稻田土壤有效态微量元素的影响

Effect of O_3 enrichment on concentrations of DTPA-extractable microelements of soils in the rice season

利用中国稻/麦轮作系统O3-FACE(Ozone-Free Air Concentration Enrichment)试验平台,研究大气O3浓度升高(比周围大气高50%)对2009年稻季各生育期不同深度(0-5 cm,5-10 cm和10-15 cm)耕层土壤微量元素有效性的影响。结果表明,大气O3浓度增加对0-15 cm耕层土壤有效性-Fe、Mn、Cu、Zn的提高幅度分别为10.0%、8.1%、5.4%、40.3%,其中对Cu的提高幅度达显著水平;不同土壤有效态微量元素在土壤垂直分布规律不同,土壤有效态Fe、Zn含量随土壤深度增加而降低,土壤有效态Mn含量随深度增加而增加,而土壤有效态Cu含量在不同深度土层中基本稳定;大气O3浓度升高对土壤DTPA提取态Fe的提高幅度随土壤深度的增加而增大,而对土壤DTPA提取态Mn、Cu、Zn的提高幅度均随土壤深度的增加而降低;大气O3浓度升高对0-5cm、5-10cm处土壤DTPA-Cu和0-5cm处Mn含量增加幅度分别为13.2%、8.9%和30.2%,且分别达显著和极显著水平。文章指出大气O3浓度升高会对稻田生态系统土壤微量元素地球化学循环产生重要影响,应针对不同层次土壤有效态微量元素含量情况,从土壤性质和水稻生长两个方面进一步明确其影响机制。

The objective of this study was to investigate the effects of atmospheric elevated O3 on concentrations of DTPA-extractable microelements of paddy soil in the rice season of wheat-rice rotation.Ozone Free-air Concentration Enrichment（O3-FACE） system at Xiaoji town,Jiangdu County,Jiangsu Province（32°35′5″N,119°42′0″E） was used in this study.Of six plots in O3-FACE system,three plots were under elevated O3 concentration （FACE） and the other three were under ambient （ambient）.The target for FACE plots was 50% higher than the ambient .Each plot had an area of 240 m2.Any one of the plots was separated from the other plots by at least 70 m to avoid cross-contamination.Concentrations of DTPA-extractable Fe,Mn,Cu and Zn at different soil depths（0-5 cm,5-10 cm and 10-15 cm） were determined under ambient and elevated ozone concentration treatment at different stages of the rice season in 2009.The results showed that elevated O3 increased the concentrations of DTPA-extractable Fe,Mn and Zn in soil at 0-15 cm depth with 10.0%,8.1% and 40.3%,respectively and significantly increased the concentrations of DTPA-extractable Cu with 5.4%（P=0.049）.Vertical distribution of DTPA-extractable microelements in soil differed with different microelements.Concentrations of DTPA-extractable Fe and Zn in soil decreased with soil depth,while concentration of DTPA-extractable Mn in soil increased with soil depth and concentration of DTPA-extractable Cu in soil was relatively stable at different depths.There had diverse effects of O3 enrichment on concentration of soil DTPA-extractable microelements at different depth of soil.The effect of O3 enrichment on concentration of soil DTPA-extractable Fe increased with soil depth,while the effects of O3 enrichment on concentration of soil DTPA-extractable Mn,Cu and Zn decreased with soil depth.Atmospheric elevated O3 significantly increased concentrations of DTPA-extractable Cu at 0-5 cm,5-10 cm and DTPA-extractable Mn at 0-5 cm depth of soil with 13.2%（P=0.013）,8.9%（P=0.026） and 30.2%（P=0.003）,respectively.The possible mechanisms related the effects of elevated O3 on concentrations of DTPA-extractable microelements of paddy soil were discussed in this paper.Results from this study indicated that the geochemistry cycle of microelements in paddy soils in the agricultural ecosystem can be influenced by elevated O3 in the atmosphere;in order to understand the impact mechanism of elevated O3 on concentrations of DTPA-extractable microelements in soil,soil properties and rice growth,together with the microelement status at different soil depths should be considered.Based on the previous studies in CO2-FACE system,CO2 enrichment also can affect concentration of soil DTPA-extractable microelements,therefore,the combined influence of simultaneously elevated O3 and CO2 on the geochemistry cycle of microelements in paddy soils should be studied in the future.