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以三江平原典型多级沟渠系统(毛渠-农渠-斗渠-支渠-干渠)为对象,研究了其0~60 cm沉积物全铁含量的空间分布特征.结果表明,多级沟渠系统中沉积物的平均铁含量为(3.02±0.10)×104mg.kg-1,各类型、各等级的沉积物铁含量具有极显著差异(F=6.261,p 0.001),最高值出现在农田斗渠(3.71×104mg.kg-1)中,而最低值出现在湿地斗渠(2.43×104mg.kg-1)中.整个多级沟渠系统沉积物各层的铁含量没有显著性差异(F=0.093,p=0.693),但与沟渠相邻湿地同深度土层的铁含量相比,沟渠沉积物0~10 cm层、10~20 cm层分别增加了51.96%、62.22%.铁虽然具有一定的可迁移性,其最大累积处仅能延伸到第三等级的斗渠中,而非逐级递增.由于湿地保护和气候干热化,现阶段本区含铁径流量有逐渐减少的趋势.沉积物各层铁含量沿沟渠类型和等级的递变揭示了铁输移的历史变迁.
Taking the typical multistage ditches system (furrow - agricultural canal - ditch - branch canal - main channel) in the Sanjiang Plain as an example, the spatial distribution characteristics of total iron content in the sediment of 0 ~ 60 cm were studied. The results show that the sediment (3.02 ± 0.10) × 104 mg · kg-1. The iron content of sediment in all types and grades had extremely significant difference (F = 6.261, p 0.001), and the highest value appeared in farm ditch (3.71 × 104mg · kg-1), while the lowest value was found in the wet ditches (2.43 × 104mg · kg-1). There was no significant difference in the iron content of all layers of sediment (F = 0.093, p = 0.693 ), Compared with the iron content in the soil layer of the adjacent wetland and the depth of the ditch, the ditch sediments increased by 51.96% and 62.22% in the 0-10 cm layer and the 10-20 cm layer, respectively. Although iron has a certain mobility, The maximum accumulation can only extend to the third level of the bucket channel instead of increasing step by step.As the protection of wetlands and the dry climate, the present runoff rate of iron in this area has gradually decreased.The content of iron Changes along the ditch types and gradients reveal the historical changes in iron transport.