Dissolved load of the Loire River: chemical and isotopic characterization
Dissolved load of the Loire River: chemical and isotopic characterization
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DOI：
10.1016/s0009-2541(99)00247-8
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发表时间：
2000-10-01
期刊：
影响因子：
3.9
通讯作者：
Grimaud, D
中科院分区：
文献类型：
--
作者：
Grosbois, C;Negrel, P;Grimaud, D
卢瓦尔河是法国最大的流域之一，自1994年以来一直在奥尔良市外进行监测。根据河水流量，每隔2 ~ 1周测定理化参数和主微量元素。采样点占卢瓦尔河流域总采样点的34%，其中硅酸盐岩占76%，碳酸盐岩占24%，元素主要以溶解相运移，总溶解盐（TDS）与悬浮物（SM）之比在1.6 ~ 17.4之间。因此，岩石和土壤的化学风化作用是卢瓦尔河水组成的主要机制。最高的TDS/SM比率是由于溶解的人为输入。数据库显示NO3含量和河流流量之间没有联系。Na+、K+、Mg2+、SO42-和Cl-浓度随着流量的增加而降低，这与至少涉及两种成分的混合过程相一致：第一种成分（低流量时）浓度较高，可能与地下水和污水站水的输入有关；第二种成分（高流量时）浓度较低，与基岩风化和雨水输入有关。HCO3-和Ca2+也具有地球化学行为模式，它们的浓度随着流量的增加而增加，达到300 m(3)/s后，它们的浓度随着流量的增加而降低。溶解负荷的Sr同位素组成至少受5个组分控制，即由(a)硅酸盐和碳酸盐基岩排水、(b)地下水和(c)雨水代表的一系列自然组分，以及2种人为组分。本研究的目的是描述混合模型，以估计每个成分的贡献。最后，卢瓦尔河上游流域的具体出口速率被评估为接近12 t /年（-1）km（-1）的硅酸盐速率和47 t /年（-1）km（-2）的碳酸盐速率。(C) 2000 Elsevier Science B.V.版权所有
The Loire River, with one of the largest watersheds in France, has been monitored just outside the city of Orleans since 1994. Physico-chemical parameters and major and trace elements were measured between 2-day and 1-week intervals according to the river flow. The sampling site represents 34% of the total Loire watershed with 76% silicate rocks and 24% carbonate rocks,Elements are transported mainly in the dissolved phase with the ratio of total dissolved salts (TDS) to suspended matter (SM) ranging between 1.6 and 17.4. Chemical weathering of rocks and soils are thus the dominant mechanisms in the Loire waters composition. The highest TDS/SM ratios are due to dissolved anthropogenic inputs. The database shows no link between NO3- content and river flow. The Na+, K+, Mg2+, SO42-, and Cl- concentrations are seen to decrease with increasing discharge, in agreement with a mixing process involving at least two components: the first component (during low flow) is concentrated and may be related with input from the groundwater and sewage station water, the second component (during high flow) is more dilute and is in agreement with bedrock weathering and rainwater inputs. A geochemical behaviour pattern is also observed for HCO3- and Ca2+ species, their concentrations increase with increasing discharge up to 300 m(3)/s, after which, they decrease with increasing discharge. The Sr isotopic composition of the dissolved load is controlled by at least five components - a series of natural components represented by (a) waters draining the silicate and carbonate bedrock, (b) groundwater, and (c) rainwaters, and two kinds of anthropogenic components.The aim of this study is to describe the mixing model in order to estimate the contribution of each component. Finally, specific export rates in the upper Loire watershed were evaluated close to 12 t year(-1) km(-1) for the silicate rate and 47 t year(-1) km(-2) for the carbonate rate. (C) 2000 Elsevier Science B.V. All rights reserved.