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

In the environment, a pollutant is rarely present alone, and other contaminants can influence its fate. To investigate the influence of the presence of other pollutants on the sorption of pesticides and trace metals (TM), the adsorption of Aclonifen, alachlor, Cd and Cu onto suspended particulate matter (SPM) was studied. SPM was isolated during the flood event of May 2010 in the Save agricultural watershed of SW France. Adsorption equilibrium was reached after 2 h of contact with SPM for pesticides and 24 h for TM. To simulate natural conditions, the SPM load allowing a maximum adsorption of pollutants was set at 1 g L-1 and the concentration of pollutants at 10 g L-1. These factors being established, the co-presence experiments showed that most contaminants were influenced by the presence of other pollutant(s) in the water, trace metals to a lesser extent than pesticides. The mutual influence can be either competition for the same adsorption sites or formation of new complexes between pollutants. These phenomena can modify the adsorption capacities of each pollutant. The order of introduction into the aqueous solution also influenced the amount of adsorption of pollutants onto SPM. These results open new perspectives on the fate of pollutants.