Veterinary pharmaceuticals (VPs) are emitted into the environment and transfer to groundwater and surface water is diffuse and complex, whereas actual information on the fate is frequently limited. For 17 VPs of potential concern in the Netherlands, we assessed sources and emission due to animal slurry applications to soil. Hence, we examined the use of VPs in four livestock sectors in the Netherlands for 2015-2018, and quantified animal excretion rates and dissipation during slurry storage. For almost all VPs, administrated quantities to the animals during the period 2015-2018 decreased. VP concentrations during a storage period of six months could decrease between 10 and 98% depending on the compound. Predicted concentrations of VPs in slurries after storage compared well with measured concentrations in the literature. Based on the storage model outcomes, we developed a residue indicator, that quantifies the potential for residues in applied slurry. This indicator agrees well with the most frequently detected VPs in the Dutch slurries, and is therefore useful to prioritize measures aiming at reducing VP emissions into the environment.

Veterinary pharmaceuticals (VPs) residues may end up on the soil via manure, and from there can be transported to groundwater due to leaching. In this study an analytical framework to estimate the leaching potential of VPs at the national scale is presented. This approach takes soil-applied VPs concentrations, soil-hydraulic and soil-chemical properties, groundwater levels, sorption and degradation of VPs into account. For six commonly soil-applied VPs in the Netherlands, we assess quantities leached to groundwater and their spatial distribution, as well as the relative importance of processes that drive leaching. Our results for VPs Oxytetracycline, Doxycycline, and Ivermectin indicate that maximum quantities that may leach to groundwater are very low, i.e. ≪1 μg/ha, hence spatial differences are not investigated. For VPs Sulfadiazine and Flubendazole we identify a few regions that are potentially prone to leaching, with leached quantities higher than 1 μg/ha. Leaching patterns of these two VPs are dominated by soil properties and groundwater levels rather than soil-applied quantities. For Dexamethasone, even though applied on the soil in much lower concentrations compared to other investigated VPs, spatially widespread leaching to groundwater is found, with leached quantities higher than 1 μg/ha. Due to the leaching affinity of Dexamethasone, variations in the soil-applied amounts have significant influence on the quantities leached to groundwater. Dexamethasone is highlighted as important for the future environmental risk assessment efforts. This study has shown that the leaching potential of VPs is not determined by one single parameter, but by a combination of parameters. This combination also depends on the compound investigated.

Compounds originating from animal husbandry can pollute surface water through the application of manure to soil. Typically, grab sampling is employed to detect these residues, which only provides information on the concentration at the time of sampling. To better understand the emission patterns of these compounds, we utilized passive samplers in surface water to collect data at eight locations in a Dutch agricultural region, during different time intervals. As a passive sampler, we chose the integrative-based Speedisk® hydrophilic DVB. In total, we targeted 46 compounds, among which 25 antibiotics, three hormones, nine antiparasitics, and nine disinfectants. From these 46 compounds, 22 compounds accumulated in passive samplers in amounts above the limit of quantification in at least one sampling location. Over the 12-week deployment period, a time integrative uptake pattern was identified in 53% of the examined cases, with the remaining 47% not displaying this behavior. The occurrences without this behavior were primarily associated with specific location, particularly the most upstream location, or specific compounds. Our findings suggest that the proposed use of passive samplers, when compared in this limited context to traditional grab sampling, may provide enhanced efficiency and potentially enable the detection of a wider array of compounds. In fact, a number of compounds originating from animal husbandry activities were quantified for the first time in Dutch surface waters, such as flubendazole, florfenicol, and tilmicosine. The set-up of the sampling campaign also allowed to distinguish between different pollution levels during sampling intervals on the same location. This aspect gains particular significance when considering the utilization of different compounds on various occasions, hence, it has the potential to strengthen ongoing monitoring and mitigation efforts.

Low-cost capacitive (LCC) soil moisture sensors have considerable potential for precision agriculture due to their low cost, low energy consumption, and suitability for IoT-based systems. However, their field performance and the transferability of laboratory calibration to field conditions remain insufficiently documented. The objective of this study was to evaluate the field performance of LCC sensors calibrated in the laboratory and to assess practical calibration strategies for field application. Laboratory calibration was performed for eight soil types, and field performance was evaluated in four experiments under different soil and climatic conditions. The sensors showed high accuracy under laboratory conditions, with RMSE values of 0.002–0.022 m³/m³ for soil-specific calibration, but substantially larger errors when laboratory-derived calibrations were applied directly in the field (RMSE 0.055–0.191 m³/m³). Soil-specific field calibration gave the highest accuracy (RMSE 0.005–0.036 m³/m³), whereas a simplified one-point calibration also improved performance considerably (RMSE 0.006–0.078 m³/m³) while requiring much less effort. Sensor performance declined at high water contents and under saline conditions. The results show that low-cost capacitive sensors can be used for reliable field soil moisture monitoring.

Livestock animals are commonly treated with veterinary pharmaceuticals (VPs), and their residues often enter the environment through manure applied to soil. A fraction of these residues may be further transported to surface waters through intricate transport mechanisms. Here, we examine the temporal dynamics of VPs in lowland surface waters of an agricultural catchment in the Netherlands, utilizing information on VPs concentrations in manure (2015-2020) and surface water measurements collected in 2020. We first calculate the amounts of two VPs (flubendazole and sulfadiazine) applied in the catchment of interest and analyze the local manure application practices to establish the temporal distribution of VP application. We then develop a parsimonious catchment-scale transport model for VPs that is based on time-variable water transit time distributions. The transport model considers multiple processes experienced by the VPs during their transfer to the stream network, including evapoconcentration, sorption and degradation. Despite the uncertainties associated with VP transport processes, the model accurately captures the order of magnitude of VP concentration in stream water for two VPs characterized by contrasting sorption and degradation rates. To interpret our simulations, we investigate water and solute transit times and their variability due to changing hydrological conditions. Our results suggest that, despite the mean water transit times of some years typical of lowland catchments, as well as relatively strong VP sorption or rapid degradation, detectable amounts of VPs in the order of 1-10 ng/L may reach the stream ecosystem through fast flowpaths characterized by short transit times.