Impact of environmental factors on in situ determination of iron in seawater by flow injection analysis     

Agathe Laës  Renaud Vuillemin  Bernard Leilde  Graldine Sarthou  Claudie Bournot-Marec  Stphane Blain 《Marine Chemistry》2005,97(3-4):347-356

A sensitive method for iron determination in seawater has been adapted on a submersible chemical analyser for in situ measurements. The technique is based on flow injection analysis (FIA) coupled with spectrophotometric detection. When direct injection of seawater was used, the detection limit was 1.6 nM, and the precision 7%, for a triplicate injection of a 4 nM standard. At low iron concentrations, on line preconcentration using a column filled with 8-hydroxyquinoline (8HQ) resin was used. The detection limit was 0.15 nM (time of preconcentration = 240 s), and the precision 6%, for a triplicate determination of a 1 nM standard, allowing the determination of Fe in most of the oceanic regimes, except the most depleted surface waters. The effect of temperature, pressure, salinity, copper, manganese, and iron speciation on the response of the analyser was investigated. The slope of the calibration curves followed a linear relation as a function of pressure (C_p = 2.8 × 10^{− 5}P + 3.4 × 10^{− 2} s nmol^{− 1}, R² = 0.997, for Θ = 13 °C) and an exponential relation as a function of temperature (C_Θ = 0.009e^0.103Θ, R² = 0.832, for P = 3 bar). No statistical difference at 95% confidence level was observed for samples of different salinities (S = 0, 20, 35). Only very high concentration of copper (1000 × [Fe]) produced a detectable interference. The chemical analyser was deployed in the coastal environment of the Bay of Brest to investigate the effect of iron speciation on the response of the analyser. Direct injection was used and seawater samples were acidified on line for 80 s. Dissolved iron (DFe, filtered seawater (0.4 μm), acidified and stored at pH 1.8) corresponded to 29 ± 4% of Fe_a (unfiltered seawater, acidified in line at pH 1.8 for 80 s). Most of Fe_a (71 ± 4%) was probably a fraction of total dissolvable iron (TDFe, unfiltered seawater, acidified and stored at pH 1.8).  相似文献   

Modeling the sediment yield and the impact of vegetated filters using an event‐based soil erosion model—a case study of a small Canadian watershed          下载免费PDF全文

Gabriel Hould‐Gosselin  Alain N. Rousseau  Silvio J. Gumiere  Dennis W. Hallema  Claudie Ratté‐Fortin  Georges Thériault  Eric van Bochove 《水文研究》2016,30(16):2835-2850

This paper presents the first application of the event‐based MHYDAS‐Erosion model to a small agricultural watershed under temperate climate conditions (Quebec, Canada). Simulation results based on observed and synthetic rainfall events revealed a bimodal behaviour of sediment yield. During high‐intensity rainfall events, most of the sediments reaching the watershed outlet originate from cropland. Meanwhile, during low‐intensity events, most of the sediments come from the drainage network. Furthermore, simulation results show that implementation of 5‐m and 20‐m wide vegetated filters throughout the watershed or at the edge of the most problematic fields (4% of the total fields) could reduce soil loss by 52% and 31%, respectively. The modeling framework could be used for the design and location of beneficial management practices such as grass strips and riparian zones Copyright © 2016 John Wiley & Sons, Ltd.  相似文献