School of Renewable Natural Resources, Louisiana State University Agricultural Center, Renewable Natural Resources Building Room 220, Baton Rouge, LA, 70803, USA.
School of Renewable Natural Resources, Louisiana State University Agricultural Center, Renewable Natural Resources Building Room 220, Baton Rouge, LA, 70803, USA; Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, 70803, USA.
Chemosphere. 2018 Aug;205:559-569. doi: 10.1016/j.chemosphere.2018.04.094. Epub 2018 Apr 17.
Discharging 680 km of freshwater annually to the Northern Gulf of Mexico (NGOM), the Mississippi-Atchafalaya River System (MARS) plays a significant role in transporting major and trace elements to the ocean. In this study, we analyzed total recoverable concentrations of thirty-one metals from water samples collected at five locations along the MARS during 2013-2016 to quantify their seasonal mass exports. The Atchafalaya River flows through a large swamp floodplain, allowing us to also test the hypothesis that floodplains function as a sink for metals. We found that the seven major elements (Ca, Na, Mg, Si, K, Al, and Fe) constituted 99% of the total annual mass load of metals (7.38 × 10 tons) from the MARS. Higher concentrations of Al, Ba, B, Ca, Fe, Mg, Mn, Ag, and Ti were found in the Mississippi River, while significantly higher Si and Na concentrations were found in the Atchafalaya River. Significant relationships were found between daily discharge and daily loads of Ba, Ca, Fe, K, Sr, and Ti in both rivers, while significant relationships were also found for Al, Mg, Mn, V, and Zn in the Atchafalaya River and B in the Mississippi River. Overall, the Mississippi River contributed 64-76% of the total annual loading of metals from the MARS to the NGOM. Daily loads of Al, Ba, B, Fe, Li, Mn, P, K, Si, Ag, Ti, V, and Zn regularly decreased upstream to downstream in the Atchafalaya River, partially accepting the initial hypothesis on metals transport in river floodplains.
密西西比-阿查法拉亚河系统（MARS）每年向墨西哥湾北部（NGOM）排放 680 公里的淡水，在将主要和微量元素输送到海洋方面发挥着重要作用。在这项研究中，我们分析了 2013 年至 2016 年期间在 MARS 五个位置采集的水样中的 31 种金属的总可回收浓度，以量化它们的季节性质量出口。阿查法拉亚河流经一个大型沼泽泛滥平原，这使我们能够检验泛滥平原作为金属汇的假设。我们发现，七种主要元素（Ca、Na、Mg、Si、K、Al 和 Fe）构成了 MARS 中金属年总质量负荷（7.38×10 吨）的 99%。密西西比河的 Al、Ba、B、Ca、Fe、Mg、Mn、Ag 和 Ti 浓度较高，而阿查法拉亚河的 Si 和 Na 浓度明显较高。在两条河流中，均发现每日流量与每日 Ba、Ca、Fe、K、Sr 和 Ti 负荷之间存在显著关系，而在阿查法拉亚河的 Al、Mg、Mn、V 和 Zn 以及密西西比河的 B 中也发现了显著关系。总体而言，密西西比河对 MARS 向 NGOM 输送的金属总年负荷的贡献率为 64-76%。在阿查法拉亚河，Al、Ba、B、Fe、Li、Mn、P、K、Si、Ag、Ti、V 和 Zn 的日负荷从上游到下游定期减少，这部分接受了关于河流泛滥平原中金属运输的初始假设。
