Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Desorption kinetics of sulfonamide and trimethoprim antibiotics in soils assessed with diffusive gradients in thin-films
AU - Chen, Chang-Er
AU - Jones, Kevin C.
AU - Ying, Guang-Guo
AU - Zhang, Hao
PY - 2014/4/4
Y1 - 2014/4/4
N2 - Although sorption/desorption of antibiotics in soils affects their mobility and availability, with consequences for risks to the surrounding environment, the dynamics of these processes are not well-known. In this study, diffusive gradients in thin-films devices suitable for measuring polar organic compounds (o-DGT) were deployed in two soils for a range of times (5 h to 20 d) to measure the distribution and rates of exchange between solid phase and solution of three sulphonamides (SAs; sulfamethoxazole, SMX; sulfamethazine, SMZ; and sulfadimethoxine, SDM) and trimethoprim (TMP). o-DGT continuously removes antibiotics to a XAD gel layer after passage through a well-defined diffusion layer and therefore perturbs their concentration in the adjacent soil solution. This induces a remobilization flux from the solid phase, which is related to the concentration of antibiotics in the soil solution, their diffusional supply, and the exchange kinetics between dissolved and sorbed antibiotics. A dynamic model of solute interactions called DIFS (DGT induced fluxes in soils) was used to derive distribution coefficients for labile antibiotics (Kdl) and the rate constant for supply of antibiotics from solid phase to solution, expressed as a response time (Tc). Larger labile solid phase pools were observed for TMP than for SAs. The soils could resupply TMP so rapidly that in one soil, where Tc = 2 min, supply was controlled by diffusion. Response times for SAs were generally longer (>27 min), particularly for SDM (>3 h), implying that the supply of SAs to o-DGT samplers was limited by the desorption release rate. A wider implication of this study is that similar solid phase release kinetics may control the uptake of antibiotics by biota.
AB - Although sorption/desorption of antibiotics in soils affects their mobility and availability, with consequences for risks to the surrounding environment, the dynamics of these processes are not well-known. In this study, diffusive gradients in thin-films devices suitable for measuring polar organic compounds (o-DGT) were deployed in two soils for a range of times (5 h to 20 d) to measure the distribution and rates of exchange between solid phase and solution of three sulphonamides (SAs; sulfamethoxazole, SMX; sulfamethazine, SMZ; and sulfadimethoxine, SDM) and trimethoprim (TMP). o-DGT continuously removes antibiotics to a XAD gel layer after passage through a well-defined diffusion layer and therefore perturbs their concentration in the adjacent soil solution. This induces a remobilization flux from the solid phase, which is related to the concentration of antibiotics in the soil solution, their diffusional supply, and the exchange kinetics between dissolved and sorbed antibiotics. A dynamic model of solute interactions called DIFS (DGT induced fluxes in soils) was used to derive distribution coefficients for labile antibiotics (Kdl) and the rate constant for supply of antibiotics from solid phase to solution, expressed as a response time (Tc). Larger labile solid phase pools were observed for TMP than for SAs. The soils could resupply TMP so rapidly that in one soil, where Tc = 2 min, supply was controlled by diffusion. Response times for SAs were generally longer (>27 min), particularly for SDM (>3 h), implying that the supply of SAs to o-DGT samplers was limited by the desorption release rate. A wider implication of this study is that similar solid phase release kinetics may control the uptake of antibiotics by biota.
U2 - 10.1021/es500194f
DO - 10.1021/es500194f
M3 - Journal article
VL - 48
SP - 5530
EP - 5536
JO - Environmental Science and Technology
JF - Environmental Science and Technology
SN - 0013-936X
IS - 10
ER -