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首页> 外文期刊>Estuarine Coastal and Shelf Science >Salt marsh plants (Juncus maritimus and Scirpus maritimus) as sources of strong complexing ligands
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Salt marsh plants (Juncus maritimus and Scirpus maritimus) as sources of strong complexing ligands

机译：盐沼植物（Juntus maritimus和Scirpus maritimus）是强络合配体的来源

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This work aimed to evaluate, in vitro, the capability of roots of salt marsh plants to release strong Cu-complexing ligands and to ascertain whether Cu contamination would stimulate ligands' exudation or not. The sea rush Juncus maritimus and the sea-club rush Scirpus maritimus, both from the lower Douro river estuary (NW Portugal), were used. Plants were collected seasonally, four times a year in 2004, during low tide. After sampling, plant roots were washed for removal of adherent particles and immersed for 2 h in a solution that matched salinity (3) and pH (7.5) of the pore water from the same location and spiked with Cu~(2+) in the range 0—1600 nM to obtain plant exudates. In the final solutions as well as in sediment pore water total dissolved Zn and Cu, Cu-complexing ligand concentrations and the respective conditional stability constants (K'_(CuL)) values were determined by voltammetry. This study demonstrated that plants are able to release, in a short period of time, relatively high amounts of strong Cu-complexing ligands (56—265 nmol gmot), which differed among plants and sampling site but were independent of the season. Cu contamination did not stimulate exudation of Cu-complexing ligands. On the other hand, in media contaminated with Cu both plants accumulated relatively high amounts (29—83%) of the initially dissolved Cu, indicating that they have alternative internal mechanisms for Cu detoxification. Cu exchange between roots and medium (either accumulation in contaminated medium or release in the absence of Cu) was more intense for 5. maritimus than for J. maritimus. It was observed that exudate solutions obtained in the absence of added Cu and sediment pore water (the densities of roots observed inside the salt marsh where comparable to those used in the in vitro experiments), displayed similarities in terms of total dissolved metals, Cu-complexing ligands concentrations, values of K'_(CuL) (12 ＜ log K'_(CuL) ＜ 14), as well as patterns of variation among seasons (only observed for Zn). These results are novel and point out that salt marsh plants may be the source at least partially of the strong organic ligands found in the sediment pore water in shallow marginal areas. The capability of salt marsh plants to release strong organic ligands into the environment, conjugated with their known capacity to oxidize anaerobic sediment around roots, indicate that these plants can play a role in controlling metal speciation in the water/sediment interface.
机译：这项工作的目的是在体外评估盐沼植物根部释放强大的铜络合物配体的能力，并确定铜污染是否会刺激配体的渗出。使用都来自杜罗河下游河口（葡萄牙西北部）的海峰海鲈（Juncus maritimus）和海浪海峰（Scirpus maritimus）。在退潮期间，按季节采集植物，2004年每年采集四次。取样后，将植物根部洗净以除去粘附的颗粒，并在同一位置将其浸入与孔隙水的盐度（3）和pH（7.5）相匹配的溶液中2小时，并在其中加入Cu〜（2+）。范围为0-1600 nM，以获得植物渗出液。在最终溶液中以及在沉积物孔隙水中，总溶解的Zn和Cu，Cu络合配体浓度和相应的条件稳定性常数（K'_（CuL））值通过伏安法测定。这项研究表明，植物能够在短时间内释放相对大量的强铜络合配体（56-265 nmol gmot），这在植物和采样地点之间有所不同，但与季节无关。铜污染不会刺激铜络合配体的渗出。另一方面，在被铜污染的培养基中，两株植物累积了相对较高的量（29-83％）的最初溶解的铜，表明它们具有替代性的内部机理来解毒铜。 5. maritimus的根与培养基之间的Cu交换（在受污染的培养基中积累或在没有Cu的情况下释放）比J. maritimus更为强烈。观察到，在不添加铜和沉积物孔隙水的情况下获得的渗出液（盐沼内部观察到的根的密度与体外实验中使用的相当）在总溶解金属，Cu-络合配体浓度，K'_（CuL）值（12 ＜log K'_（CuL）＜14）以及季节之间的变化模式（仅在Zn中观察到）。这些结果是新颖的，指出盐沼植物可能至少部分是浅边缘地区沉积物孔隙水中发现的强有机配体的来源。盐沼植物释放强大的有机配体到环境中的能力，加上其已知的氧化根周围厌氧沉积物的能力，表明这些植物可以在控制水/沉积物界面中的金属形态中发挥作用。

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