1533 / 2019-08-15 09:03:35

In situ understanding the sorption-desorption of Antibiotics in Soil with o-DGT and implications

17、土壤科学与环境健康 > 专题8：有机污染物的土壤环境行为及其生态效应

Adverse effects of antibiotics has raised concerns in environmental science and ecology1, 2. The availability, rather than total concentration in the soil determines the toxicity of antibiotics in soil. In situ tool like the well-known Diffusive Gradients in Thin-film (DGT) which has been extended to organics (o-DGT)3 would be a potential novel approach for understanding the avalability of organics.
We introduced, for the first time, o-DGT to the soil systems for understanding the sorption-desorption of antibiotics. Resutls showed that the concentration in the soil solution were only partially sustained by release of these antibiotics from the solid phase. The potential fluxes of these antibiotics in this soil were 1.2, 3.6, 5.4 and 2.4 pg/cm2/s for TMP, SMZ, SMX and SDM, respectively4. This induces a remobilization flux from the solid phase. With the aid of the DGT induced fluxes in soils (DIFS) model, distribution coefficients for labile antibiotics (Kdl) and the rate constant of sorption (k1) and desorption (k-1), as well as the response time (Tc) were derived. Larger labile solid phase pools were observed for TMP than 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 (>3h), implying that the supply of SAs to o-DGT samplers was limited by the desorption release rate5.
o-DGT is a promising tool for understanding the fate and behaviours of polar organic chemicals in soil, and it provides a potential in situ approach for assessing their bioavailability.