| 沟渠化对三江平原湿地铁元素沉积过程的影响 |
| 摘要点击 2608 全文点击 1038 投稿时间：2014-09-29 修订日期：2014-11-07 |
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| 中文关键词 沟渠化 沉积通量 铁氧化物 养分迁移 三江平原 |
| 英文关键词 canalization deposition flux iron oxides nutrients transfer Sanjiang Plain |
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| 中文摘要 |
| 沟渠化是湿地垦殖的标志性过程和景观. 在三江平原洪河国家级自然保护区附近选择了一个典型四级排水沟渠系统,沿等级在沟渠底部布设沉积板,并以附近的河漫滩天然湿地为对照,连续两年定量采集了不同级别沟渠和天然湿地中的当年沉积物,分别计算了沉积通量和沉积物中的铁元素及其氧化物和生源要素含量. 结果表明,各等级沟渠的枯落物、泥沙和总沉积通量都没有显著性差异,其均值分别为(57.00±16.90)、(3997.57±798.98)和(4054.57±792.91) g ·(m2 ·a)-1,其中枯落物所占比例随沟渠等级增加而逐渐降低; 天然湿地的枯落物沉积通量[(120.26±19.42) g ·(m2 ·a)-1]显著高于沟渠,而泥沙[(35.41±11.15) g ·(m2 ·a)-1]和总沉积通量[(155.67±20.75) g ·(m2 ·a)-1]则显著低于沟渠; 各级沟渠和天然湿地沉积物中的总铁含量没有显著性差异,但游离态铁含量显著低于天然湿地; 农渠、斗渠和支渠沉积物的无定形铁和络合态铁含量都与天然湿地接近,且都高于干渠沉积物; 各级沟渠沉积物中铁氧化物的游离度为天然湿地的60.2%,而络合度和活化度都没有显著性差异; 各级沟渠沉积物中的总有机碳、总氮和总磷含量都没有显著差异,但都低于天然湿地,分别为天然湿地的14.6%、31.6%和41.0%. 三江平原湿地垦殖形成的沟渠化对天然湿地的铁和生源要素沉积产生了显著影响,合理的农田用水管理才能避免由此带来的环境生态风险. |
| 英文摘要 |
| Canalization is the representative process and landscape of wetland reclamation. A typical ditch system of four levels near the Honghe National Nature Reserve in Sanjiang Plain was selected. Deposition plates were set on the sediments along the ditch level and the remained natural wetland nearby was quantitatively sampled for two years as the control. The deposition fluxes, total iron concentration, iron oxides and their components, as well as biogenic elements in the sediments collected by deposition plates were measured. The results showed that the litter, mud/sand and total deposition fluxes showed no significant differences between different ditch levels, with the means of (57.00±16.90) g ·(m2 ·a)-1, (3997.57±798.98) g ·(m2 ·a)-1 and (4054.57±792.91) g ·(m2 ·a)-1, respectively. The litter flux decreased with the increase of ditch level, and the flux in the natural wetland [(120.26±19.42) g ·(m2 ·a)-1] was significantly greater than that of the ditches. The mud/sand [(35.41±11.15) g ·(m2 ·a)-1] and total deposition fluxes [(155.67±20.75) g ·(m2 ·a]-1] were significantly smaller than those of the ditches. There were no significant differences in the total iron between different ditches and natural wetland, while the free iron oxide content in the ditch sediments was significantly lower than that of natural wetland sediment. Except for the main ditch, the amorphous and complex iron oxides in the other ditch and natural wetland sediments showed no significant differences. The free degree of the iron oxide in ditch sediments was 60.2% of that in the natural wetland, while the differences in the complex degree and the activated degree were insignificant. The differences in the total organic carbon, total nitrogen and total phosphorus were insignificant, and all were smaller than those of the natural wetland, with the percentages of 14.6%, 31.6% and 41.0%, respectively. It could be concluded that the effects of canalization on iron and biogenic elements were significant. Consequently, rational agricultural water managements are strongly recommended to avoid the potential environmental and ecological risks caused by canalization in Sanjiang Plain. |
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