Trace Element and Pesticide Dynamics During a Flood Event in the Save Agricultural Watershed: Soil-River Transfer Pathways and Controlling Factors

Abstract

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Adsorption of Aclonifen, Alachlor, Cd and Cu onto Natural River Suspended Matter in the Context of Multi-Pollutions: Influence of Contaminant Co-Presence and Order of Input into the Aqueous Solution

“…The mean instant discharge increased from 3 m 3 s −1 to almost 50 m 3 s −1 at the peak stormflow ( Figure 2). This flood event was intensively sampled to study the transfer dynamics of organic and inorganic contaminants from the soils to the river in relation to the discharges of the different stormflow components [12].…”

“…Both water and solid materials used were meticulously characterized for major and trace elements as well as pesticides prior to the mixture experiments. Details of the physicochemical characterizations of water and sediments are presented in [12] and listed in the results tables.…”

“…Two non-ionic pesticides were chosen, one more soluble and one less soluble: Alachlor (Ala; solubility: 342 mg L −1 ; Kow = 3.03) and Aclonifen (Aclo; solubility: 1.4 mg L −1 ; Kow = 4.67) which had been already detected in the Save river [12]. Carbon-14 labeled pesticide solutions were used to detect low concentrations efficiently.…”

“…As trace elements, two highly anthropogenic and toxic elements detected were chosen: Cd and Cu, frequently present in fertilizers and in pesticides, which were found to be moderately (for Cu) to highly (for Cd) enriched in the river bottom sediments of this area [12]. Merck standard solutions CertiPUR ® (Merck, Kenilworth, NJ, USA) Cd (Cd (NO 3 ) 2 in HNO 3 0.5 mol L −1 , 1000 mg L −1 ) and Cu (Cu (NO 3 ) 2 in HNO 3 0.5 mol L −1 , 1000 mg L −1 ) were used to prepare 1.0 mg L −1 spikes.…”

“…Merck standard solutions CertiPUR ® (Merck, Kenilworth, NJ, USA) Cd (Cd (NO 3 ) 2 in HNO 3 0.5 mol L −1 , 1000 mg L −1 ) and Cu (Cu (NO 3 ) 2 in HNO 3 0.5 mol L −1 , 1000 mg L −1 ) were used to prepare 1.0 mg L −1 spikes. These standards have very acidic pH; therefore, after their addition to the mixtures, the pH was adjusted with Merck Suprapur ® (Merck, Kenilworth, NJ, USA) sodium hydroxide (9.97 M) in order to maintain the pH at values between 8.0 and 8.5, close to the natural environmental conditions [12].…”