成都稻田水-土界面上锰形态的时空分布特征

Spatial and Temporal Distribution of Manganese Species at Soil-water Interface of Rice Paddy Field of Chengdu

以盐酸为介质,采用Tessier连续提取法及火焰原子吸收法,分析了不同时空条件下成都某地稻田水-土界面上土壤锰形态、总锰的含量及表面水、孔隙水中可溶态锰的浓度。结果表明:各形态锰含量随淹水时间、土质和灌溉条件的不同而变化。冬水田A可溶态锰的峰值于4、5、6月均出现在水-土界面下3～7 cm处,而水旱轮作田B的峰值则从4月的7～8 cm上移至5、6月的4～5 cm;2块稻田均出现氧化物结合态锰随着水淹时间延长而显著减少的现象;插秧前氧化物结合态锰含量最高,插秧后残渣态锰含量最高,容易被植物吸收利用的锰形态含量很少;2块稻田因灌溉水的酸碱性不同而导致了碳酸盐结合态锰明显不同的变化趋势。2块稻田总锰含量的平均值分别为499和507μg/g,均未超过我国土壤锰的平均含量,说明该地区未受到锰的污染。

Using hydrochloric acid as media,Tessier sequential extraction procedure was used for the fractionation of manganese species at water-soil interface in rice paddy field of Chengdu,under different spatial and temporal conditions,total Mn,Mn species in soils and dissolved Mn in surface water and pore water were determined by FAAS.The results showed that Mn species varied with water flooding time,soil property and irrigationconditions.For winter paddy field A,all dissolved manganese had the maximum concentration below water-soil interface 3-7 cm in April,May and June,while the peaks in paddy-upland rotation B shifted from 7-8 cm in April to 4-5 cm in May and June.The two fields appeared the phenomena that oxide bound manganese decreased significantly under surface water with the immersion time prolonging.Oxide bound manganese reached maximum before planting rice,while residual manganese was the highest after planting,a very small proportion of manganese species was easily absorbed by plants.There was a significantly different trend for carbonate bound manganese due to different acidity in irrigation water.The average content of the total manganese in soils of the two fields during whole sampling period was 499 and 507 μg/g,respectively,which was less than that of 710 μg/g in soils of China and indicated that there was no Mn contamination in selected rice paddy soils.