Transport and fate of veterinary sulfonamide antibiotics in soil

Sulfonamide antibiotics is one group of important pharmaceuticals in the veterinary medicine market. Discharge of antibiotics from wastewater treatment plants lead to their presence in river and groundwater. In agricultural regions, application of animal manure on crop lands is a major contamination path in the environmental matrices. Contamination by veterinary antibiotics should be managed with long-term perspectives. Most of past studies focused on the detection and monitoring of the veterinary antibiotics in agricultural land and water bodies. However, the studies provided only little quantitative knowledge on transport and fluxes of pharmaceuticals in the agricultural soils. The main purpose of this study is to investigate the transport processes of veterinary sulfonamide antibiotics (Sulfadimethoxine, Sulfamethazine, and Sulfamethoxazole) in agricultural soils in Haean catchment located in South Korea. In particular, we emphasized in detail: i) sorption and transport of the sulfonamides in structured and homogeneous soil columns, ii) distribution of the applied antibiotics in runoff and soil layer on sloped fields, iii) comparing the transport processes between sulfadimethoxine and sorbable/unsorbable tracers. In the batch sorption study, sorption of the all three sulfonamides was non-linear, and the Freundlich isotherm provided the best fits to the measured data. For all target sulfonamides, their sorbility to the soils decreased with increasing pH value of aqueous solutions in range of 4.0-8.0. An increasing sorption tendency was obtained in the following order: Sulfadimethoxine>Sulfamethoxazole> Sulfamethazine. Transport of the antibiotics in soils with different soil structures and pH conditions was quantitatively investigated with a numerical modelling program, HYDRUS-1D. The soil column studies using a conservative tracer, bromide and the antibiotics showed that an important transport mechanism in the natural soil columns can be preferential flow through macropore. A comparison of water flow and solute transport in natural and disturbed soil columns revealed that the transport processes were affected by the soil structure. The transport of the sulfonamides was typical non-equilibrium process, and their mobility was reduced with decreasing pH value. In the field campaigns, loss of the antibiotics varied between two sloped fields, and was related to the slope of the surface and precipitation. Heavy rainfalls during Monsoon season from 24 June, 2011 to 10. July, 2011 generated a huge amount of overland flow as well as seepage water in the soil layer. In accordance with the field measurements and modelling with HydroGeoSphere, water fluxes were higher for the more sloped site during the entire monsoon season. Among the sulfonamides, the mobility of sulfadimethoxine in the soil layers was relatively low. This reflects that the mobility of the sulfonamides was strongly dependent on their sorbility on soil materials. In the tracer experiments with Brilliant Blue FCF, image analysis for horizontal cross-sections of the soil columns showed that dye coverage was almost 100% in the upper 6 cm. Below the fully dye covered depth, the ratio of dye coverage decreased more rapidly for disturbed soils due to their homogeneous soil structure. Both lateral and vertical dispersion of bromide were higher compared to Brilliant Blue FCF and sulfadimethoxine, which demand more time to reach flow regions than bromide. This reflects that water flow does not coincide with transport of the sorbable solutes, Brilliant Blue FCF and the sulfonamide due to adsorption to soil materials. In summary, this thesis provided valuable knowledge about the transport phenomena of veterinary pharmaceuticals in agricultural soils. Through coupling of laboratory experiments, field campaigns and numerical modelling studies, major transport processes in soils can be quantitatively described. In this thesis, we present several recommendations, aiming at reducing the risk of pharmaceuticals in groundwater and surface water. In order to reduce residual amounts of the contaminants in the environment, direct application of animal faeces and urine to agricultural lands should be restricted. Preferential flow in macropores leads to fast movement of contaminants to deeper soil layers, which results in a high risk of groundwater pollutions. We suggests regular ploughing in order to remove rest of roots creating preferential flow paths. One important sources of the antibiotics in surface waters is runoff and soil erosion from agricultural lands. To reduce their input into surface waters, we recommend establishing buffer zones between agricultural fields and streams.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Bayreuth

Year

2015

Author dc:creator

• Park, Jong Yol

Contributors dc:contributor

• Huwe, Bernd

Repository record source_url

https://epub.uni-bayreuth.de/id/eprint/2143/

OAI identifier oai:identifier

oai:epub.uni-bayreuth.de:2143