Sulfonamide antibiotics can enter agricultural soils by fertilisation with contaminated manure. While only rough estimations on the extent of such applications exist, this pathway results in trace level contamination of groundwater. Therefore, we studied the transport of three sulfonamides in leachates from field lysimeters after application of a sulfonamide-contaminated liquid manure. In a 3-year period, the sulfonamides were determined in 64% to 70% of all leachate samples at concentrations between 0.08 to 56.7 µg L−1. Furthermore, sulfonamides were determined in leachates up to 23 months after application, which indicated a medium- to long-term leaching risk. Extreme dry weather conditions resulted in highest dislocated amounts of sulfonamides in two of the three treatments. Furthermore, soil management such as tillage and cropping affected the time between application and breakthrough of sulfonamides and the intra-annual distribution of sulfonamide loads in leachates. Although the total sulfonamide leaching loads were low, the concentrations exceeded the limit value of the European Commission of 0.1 µg biocide L−1 in drinking water in more than 50% of all samples. Furthermore, the medium-term mean concentration of the sulfonamides ranged from 0.08 and 4.00 µg L−1, which was above the limit value of the European Commission in 91 out of 158 samples. Therefore, sulfonamides applied to soils in liquid manure under common agricultural practice may cause environmental and health risks which call for a setting up of more long-term studies on the fate of antibiotics.

Soil carries out functions that are crucial for theenvironment and life on earth and is therefore an essential non renewableresource for mankind. Recently, the European Soil Framework Directive proposalindicated that soil is under increasing environmental pressure mostly due tothe intensification of human activities, which are damaging the capacity ofsoil to continue to perform in full its broad variety of crucial functions.Most of these soil functions are depending on micro-organisms inhabiting the soil.The diversity of soil micro-organisms is the highest on earth with estimates ofseveral thousand to several million different genomes per gram of soil. Howeverfundamental knowledge of the diversity and ecology of microbial communitiescarrying out soil functions is still limited. Understanding the impact ofanthropogenic activities on microbial communities and how this relates to soilfunctioning is therefore a major challenge in soil microbiology. The revolutionin the techniques available to date offer exciting opportunities for a betterunderstanding of the relationships between microbial diversity and soilfunctions. This talk will focus on the novel insights into the impact of humanactivities on microbial communities and potential consequences for ecosystemprocesses.