砷污染生境下挺水植物香蒲对砷的积累与迁移特性

为探究典型湿地挺水植物香蒲（Typha angustifolia L.）不同生长阶段对As（砷）污染生境中As累积与迁移的影响，采用室内模拟方式，通过外源添加Na₂HAsO₄·7H₂O设置不同的As污染生境，wAs（V）]分别为0、50、100、150、200、400 mg/kg，探析As胁迫下不同物候期（幼苗期、花果期、枯黄期）香蒲的生长发育、As累积特征及对土壤中As的提取迁移效果.结果表明:①As对挺水植物香蒲的生长产生低促高抑的作用，在wAs（Ⅴ）]为100~150 mg/kg处理下香蒲的生长状态显著优于其他处理；在wAs（Ⅴ）]为400 mg/kg污染生境下，香蒲的生长存在受害症状，但仍可完成整个生命期.不同生长阶段香蒲对As的耐受性特征存在差异，随着生育期的延长，植株对As污染反应的敏感性下降，表现出较强的耐受性，其中花果期最为突出，在wAs（Ⅴ）]为100 mg/kg时耐性指数最大，比0 mg/kg处理增加了54.0%.②香蒲不同部位对As的积累特征均反映出剂量依赖效应，在幼苗期、花果期和枯黄期香蒲地上部w（As）均低于地下部，转运系数均小于1；但不同生长阶段植株富集转运水平差别较大，以花果期为最高，幼苗期次之，伴随"稀释"效应的产生，枯黄期最低.③在As污染生境下，香蒲对土壤中As的去除作用大于固定作用，其迁移效果表现为花果期>枯黄期>幼苗期，在花果期进行刈割可使其发挥最佳修复效果.研究显示，挺水植物香蒲对As具有较强的耐性，并且对As的积累与迁移在不同物候期存在差异，因此，其可作为修复As污染河湖湿地土壤的推荐性植物加以深入研究与利用. 

Accumulation and Transportation of Arsenic to Wetland Plant Typha angustifolia L. in the Herbaceous Plants Grown in Arsenic-Contaminated Habitat

The accumulation and transport of arsenic (As) in typical wetland plant Typha angustifolia L. were investigated in seedling, flowering, and yellowing stages under various As stresses (0, 50, 100, 150, 200 and 400 mg/kg). The effect of As stress on plant growth and development, plant As accumulation and soil As transportation of three growth stages was examined. The results showed that:(1) Typha angustifolia L. growth was increased by low As while decreased by high As and the highest biomass production was obtained at 100-150 mg/kg As. Typha angustifolia L. showed toxic symptoms under 400 mg/kg As but can still complete its life cycle. Typha angustifolia L. in different growth stages showed different As tolerant abilities. Plant sensitivity to As stress decreased with increasing growth period, showing increased As tolerance. The greatest As tolerance was observed in flowering stage, with tolerance index being increased by 54.0% in the 100 mg/kg As treatment compared the control. (2) The As distribution in different plant tissues was dose-dependent. Shoot As concentration was higher than the root in seedling, flowering and yellowing stages, leading to the transport coefficient<1. However, the As accumulation and transportation efficiency in plants were different in three growth stages, with the highest in flowering stage and lowest in browning stage due to the biomass dilution. (3) Arsenic removal from soil was greater than that being fixed by Typha angustifolia L. under As stresses. The As transport efficiency was in order of flowering > yellowing > seedling stage. Therefore, collecting plants in flowering stage helps the greatest restoration of As-contaminated soils and/or sediments. The results showed that the emergent plant Typha angustifolia L. has strong tolerance to As and various As accumulation and transportation abilities in different phenological stages. It''s performance and mechanisms in As-contaminated wetland sediment remediation deserve further studies.