Characterization of Fe plaque and associated metals on the roots of mine-waste impacted aquatic plants
Characterization of Fe plaque and associated metals on the roots of mine-waste impacted aquatic plants
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DOI：
10.1021/es0105459
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发表时间：
2001-10-01
影响因子：
11.4
通讯作者：
Newville, M
中科院分区：
文献类型：
--
作者：
Hansel, CM;Fendorf, S;Newville, M
水生植物根部的铁斑无处不在，并且在湿地土壤中螯合金属；然而，金属螯合的机制尚未解决。因此，表征铁斑块和相关金属将有助于理解和预测湿地生态系统中的金属循环。因此，利用显微镜和光谱技术来确定常见本土湿地植物（Phalaris arundinacea）根部铁、锰、铅和锌的空间分布、关联性和化学环境。铁在根表面形成连续沉淀物，主要由水铁矿（约 63%）组成，含有少量针铁矿（32%）和少量菱铁矿（5%）。尽管 Pb 与 Fe 在根表面并列，但它与有机官能团复合，与细菌生物膜的情况一致。相比之下，锰和锌在根表面以离散、孤立的混合金属碳酸盐（菱锰矿/水锌矿）结核的形式存在。因此，土壤-根界面似乎是一个复杂的生化环境，包含还原和氧化的矿物种类，以及细菌诱导的有机金属络合物。因此，水合铁氧化物、细菌生物膜和金属碳酸盐将影响水生植物根际内金属的可用性和流动性。
Iron plaque on aquatic plant roots are ubiquitous and sequester metals in wetland soils; however, the mechanisms of metal sequestration are unresolved. Thus, characterizing the Fe plaque and associated metals will aid in understanding and predicting metal cycling in wetland ecosystems. Accordingly, microscopic and spectroscopic techniques were utilized to identify the spatial distributions, associations, and chemical environments of Fe, Mn, Pb, and Zn on the roots of a common, indigenous wetland plant (Phalaris arundinacea). Iron forms a continuous precipitate on the root surface, which is composed dominantly of ferrihydrite (ca. 63%) with lesser amounts of goethite (32%) and minor levels of siderite (5%). Although Pb is juxtaposed with Fe on the root surface, it is complexed to organic functional groups, consistent with those of bacterial biofilms. In contrast, Mn and Zn exist as discrete, isolated mixed-metal carbonate (rhodochrosite/hydrozincite) nodules on the root surface. Accordingly, the soil-root interface appears to be a complex biochemical environment, containing both reduced and oxidized mineral species, as well as bacterial-induced organic-metal complexes. As such, hydrated iron oxides, bacterial biofilms, and metal carbonates will influence the availability and mobility of metals within the rhizosphere of aquatic plants.