Pontificia Universidad Católica de Chile, Departamento de Ingeniería Hidráulica y Ambiental, Av. Vicuña Mackenna 4860, Macul, Código Postal 6904411, Santiago, Chile; Servicio de Evaluación Ambiental de Chile, Miraflores 222, piso 19, Santiago, Código Postal 8320198, Santiago, Chile.
Sci Total Environ. 2014 Jan 1;466-467:387-96. doi: 10.1016/j.scitotenv.2013.06.114. Epub 2013 Aug 7.
Fluvial sediments from two lower Loa River basin sites in northern Chile were compared in order to probe the effects of vegetation and organic matter (OM) on As accumulation in fluvial environments. The two sites were the Sloman dam, which lacks macrophytes and has a low OM content (2.4%) in sediments, and the Quillagua Oasis, which is 23 km downstream from the Sloman site and has a higher OM (6.2%) in sediments and abundant aquatic plant life. The Quillagua site had preferential As enrichment with a co-occurrence pattern that differed from that of the Sloman site, which had a lower As concentration (1528 vs. 262 mg/kg d.w., respectively). At the Quillagua site, As concentration was strongly correlated with Mn and OM (r = 0.91 and 0.85, respectively); while at the Sloman site, As concentration in sediments was significantly correlated with Ca and Sr (r = 0.63 and 0.54, respectively). Sequential extraction analyses showed that the Sloman site had higher percentage of easily exchangeable As within the surface sediment (12%, 45 mg/kg d.w.) compared with the Quillagua site (3%, 40 mg/kg d.w.). These contrasting results suggest that both vegetation and OM control the immobilization and accumulation of As in the arid Loa River basin.
为了探究植被和有机质（OM）对河流环境中砷积累的影响，对智利北部两个下洛阿河流域的河流沉积物进行了比较。这两个地点分别是斯劳曼大坝，这里缺乏大型植物，沉积物中的 OM 含量较低（2.4%）；以及奎拉瓜绿洲，位于斯劳曼大坝下游 23 公里处，沉积物中的 OM 含量较高（6.2%），水生植物丰富。奎拉瓜地区的砷富集程度较高，且具有不同于斯劳曼地区的共存模式，后者的砷浓度较低（分别为 1528 毫克/千克干重和 262 毫克/千克干重）。在奎拉瓜地区，砷浓度与锰和 OM 呈强相关（分别为 r = 0.91 和 0.85）；而在斯劳曼地区，沉积物中的砷浓度与钙和锶显著相关（分别为 r = 0.63 和 0.54）。顺序提取分析表明，与奎拉瓜地区相比（3%，40 毫克/千克干重），斯劳曼地区表层沉积物中更容易交换的砷百分比更高（12%，45 毫克/千克干重）。这些对比结果表明，植被和 OM 均控制着干旱的洛阿河流域中砷的固定和积累。
