臭氧污染对水稻土物理结构和氮磷钾含量的影响

EFFECT OF OZONE POLLUTION ON PHYSICAL STRUCTURE AND CONTENTS OF NITROGEN,PHOSPHORUS AND POTASSIUM OF PADDY SOIL

利用中国稻-麦轮作O3FACE(Free-air O3concentration enrichment)试验平台,研究了连续3年大气O3浓度升高(较周围大气高50%)对稻田表层(0～20 cm)土壤团聚体、土壤容重及孔隙度和氮磷钾养分含量的影响。结果表明,大气O3浓度升高显著增加耕层土壤0.25～0.053 mm团聚体23.5%和降低<0.053 mm团聚体24.6%。O3污染具有增大0～10 cm土层和降低10～20 cm土层土壤容重的趋势,0～10 cm土壤中气体孔隙度显著减小39.8%,10～20 cm土壤中毛管孔隙度显著增加9.1%和气体孔隙度显著减小32.4%,改变了固、液、气三相比。长期O3污染显著降低土壤全氮含量10.5%和速效钾13.3%,显著增加有效磷40.8%,但对有效氮未产生显著影响。结果表明,长期臭氧污染将改变土壤物理结构和养分物质的生物地球化学循环。

With the aid of the Free-Air ozone Concentration Enrichment （O3-FACE） system, effects of elevated atmospheric ozone （pO3） on topsoil （0 - 20 cm） aggregate, bulk density, porosity and contents of nitrogen, phosphorus and potassium of paddy soil were investigated. The paddy field had been under rice/wheat rotation and exposed to elevated atmospheric ozone, 50% higher than the ambient pO3, for three years. Results show that elevated pO3signifieantly increased 0.25 -0. 053 mm aggregates by 23.5% and significantly decreased 〈0. 053 mm slit ＋ clay fraction by 24.6% in topsoil; obviously increased soil bulk density in the 0 - 10 cm soil layer and decreased the density in the 10 - 20 cm soil layer; decreased gas porosity by 39.8% and 32.4% in the 0 - 10 em and 10 - 20 cm soil layers respectively, and increased capillary porosity by 9.1% in the 10 - 20 cm soil layer, thus altering the soil in proportion of solid, liquid and gas; reduced soil total nitrogen content by 10.5% and available potassium by 13.3% , increased available phosphorus by 40. 8% , and however, did not affect much available nitrogen. It is quite obvious that long-term exposure to elevated atmospheric pO3 will alter physical structure of the soil and biogeoehemieal cycle of nutrient substances therein.