不同水文情势下环形湿地土壤铁的时空分布特征

通过分季节原位采集三江平原环形湿地不同深度的土壤和土壤溶液，调查了土壤总铁的空间分布和土壤溶液中可溶性铁的时间变化，分析了水文情势对这种铁时空分异的影响.结果表明，环形湿地0～60 cm土层总铁的平均含量为（2.54±0.73）×10⁴mg·kg^-1，且随地表积水深度的增加由小叶章群落和乌拉苔草群落的（2.91±0.51）×10⁴ mg·kg^-1和（2.60±0.35）×10⁴mg·kg^-1逐渐下降到毛苔草和漂筏苔草群落的（2.48±0.31）×10⁴mg·kg^-1和（2.17 ± 0.31）×10⁴mg·kg^-1；常年积水土壤中铁的可溶性高于季节性积水土壤；从春季化冻开始，土壤溶液中的可溶性铁含量随积水时间的延长而逐渐增加，从6月的（0.35±0.086） mg·L^-1增加到10月上冻前的（12.67±2.92） mg·L^-1；以Fe³⁺/Fe²⁺表征的土壤还原性随积水深度或浸没时长的增加而增加；土壤溶液中的可溶性铁与pH、总有机碳、总氮和磷酸盐都具有显著或极显著相关，表明铁的分布还受土壤理化性质的影响，并与土壤碳、氮、磷的迁移转化相耦合.

patiotemporal Distribution Characteristics of Soil Iron in the Annular Wetland Under Different Water Regime

The effect of water regime on the spatial distribution of total iron and the seasonal variation of dissolved iron in a typical annular wetland of Sanjiang Plain, Northeast China, was analyzed through in situ sampling of soils and soil solutions. The results showed that the average level of total iron of the wetland soil (0-60 cm) was (2.54 ± 0.73) × 10~4mg·kg~(-1) , which decreased gradually from the Calamagrostis angustifolia community in the edge of the annular wetland (2.91 ± 0.51)× 10~4mg· kg~(-1)], to the C. meyeriana community (2.60 ± 0.35) × 10~4mg·kg~(-)], the C. lasiocarpa community (2.48 ± 0.31)×10~4mg·kg~(-1)], and the of C. pseudocuraica community (2.17 ± 0.31) ×10~4mg·kg~(-1)] in the centre of the annular wetland. The iron solubility of perennial flooding soil was higher than seasonal flooding soil. The gross dissolved iron increased from soil thawing in the late spring (0.35 ± 0.086) mg·L~(-1)] to freezing in the late autumn (12.67 ± 2.92) mg·L~(-1)], because the soil iron was activated by continuous submergence. The reduced degree as shown by Fe~(3+)/Fe~(2+) increased with the increment of water depth or flooding duration. Significant and extremely significant correlations were observed between dissolved Fe~(3+) or Fe~(2+) and pH, TOC, TN and PO_4~(3+) , which suggested that the distribution of iron was influenced by the soil physical and chemical properties, and coupled with the transfer and transformation of C, N, and P elements.