The influence mechanism of environmental factors on DGT adsorbing sulfonamides and the migration between water and sediment

Abstract

Obtaining the sulfonamides (SAs) concentrations in the water body and sediment bulk was a prerequisite to reveal their transport and partitioning behavior in sediment-water environments and accurately assess their ecological risk. In the present study, the influences of multifactor interactions on the performance of o-DGTs with XAD-18 binding gels were analyzed by central combination experiments and response surfaces analysis, in which the target compounds were 9 SAs. The results indicated that dissolved organic matter (DOM), pH, and suspended particulate matter (SS) had significant effects on the o-DGT sampling, whereas this o-DGT was independent of the ionic strength (IS). Concentning the composite influence of the four factors, the interaction between DOM and SS posed the most significant effect on all 9 SAs compounds. Subsequently, an o-DGT and DIFS model was applied to explore the SAs migration between the water-sediments interface. The difference between desorption rate (k_b) and adsorption rates (k_f) values suggested that the kinetics of SAs was dominated by adsorption. Moreover, the short-term sediment-water partitioning of SAs was clarified on the basis of distribution coefficient (K_dl) for the labile SAs, among which the sulfadiazine (SDZ) had the largest labile pool. The ability of sediments to release SAs to the liquid phase as a sink was determined by response time (T_c). Among the 9 SAs, the long-term release of soseulfamethoxypyridazine (SMP) from the solid phase of sediments would have a potential risk to the aquatic environment, to which more attention should be paid in the future.