Mobility of a pharmaceutical cocktail in soil porous media – Role of the colloidal transport

International audienc

Chemical reaction rates of ozone in water infusions of wheat, beech, oak and pine leaves of different ages

In this study we present results from a laboratory experiment designed to evaluate the first-order chemical reaction rate (k) of ozone in water films on plant leaves occurring during dew or rain events. Ozone deposition to wet cuticles is indeed known to be a significant pathway of ozone deposition, but the underlying processes are not yet well understood. Leaf infusions obtained by infusing plant leaves with water at room temperature were introduced into a wet effluent denuder fed with a flux of ozone-rich air. Ozone, water vapour concentrations and temperature were measured in both inlet and outlet airflows in order to compute ozone reaction rates kr using an ozone reaction-diffusion model in the water film. Ascorbate solutions were used to validate the set up and led to kr = 3.6 107 M−1 s−1 consistent with the literature. Ozone reaction rates were determined for wheat, beech, oak and pine leaves infusions at several developmental stages were, as well as for rain samples. Leaf infusions reaction rates were between 240 s−1 and 3.4 105 s−1 depending on species and developmental stage, while kr for rain water range from 130 to 830 s−1. Wheat leaves solutions showed significantly (P < 0.001) higher kr (median 73800 s−1) compared to the other tree species (median 4560 s−1). Senescing or dead leaves also showed significantly (P < 0.001) larger kr (median 21100 s−1) compared to non-senescent leaves (median 3200 s−1). In wheat, kr also increased with increasing yellow leaf fraction. Our results are in the range of previously reported ozone deposition on wet leaves in field or chamber studies. Composition of leaves infusions and previous studies on throughfall and dew composition shows that reaction of ozone with inorganic compounds may only explain the smallest measured kr. The largest kr observed during senescent are most likely due to reaction with organic material. This is confirmed by our LC-MS measurements which showed detection of ascorbate and VOCs as well as the reaction products of ozone with these compounds

Pharmaceuticals in soil leachates after raw and treated sludge spreading : impact of sludge treatments

Sewage sludge contains a huge diversity of organic contaminants including pharmaceuticals (1). These compounds may interact with the organo-mineral environment prevailing in such complex matrix through various sorption/complexation mechanisms. These interactions could be modified by the treatment applied to sludge and this reactivity modification could thus influence the contaminants fate after sludge disposal onto soil. In order to study the impact of sludge treatments on the fate of pharmaceuticals after sludge spreading on soil, we have conducted lab-scale leaching experiments with 4 types of sludge sampled on an industrial sludge treatment line including anaerobic digestion, drying and composting. Batch and column assays (based on EU standards XP CEN ISO/TS 21268-1, XP CEN ISO/TS 21268-2, XP CEN/TS 14997 et XP CEN ISO/TS 21268-3) and lysimeters experiments were conducted to assess contaminant release from 4 sludge: a thickened sludge (S), the same sludge after anaerobic digestion (DS), then after drying (DDS) and finally composted with green wastes (C-DDS). The release was also assessed from soil-sludge mixtures. Carbamazepin (CBZ), ciprofloxacin (CIP), sulfamethoxazole (SMX) and ibuprofen (IBP) were quantified in the raw and treated samples and in the leachates of the assays. CIP and IBP transfer from a non-contaminated soil was also assessed by means of laboratory column experiments. CIP was present at the highest concentration in the 4 sludge samples, the three other compounds were present at concentration around and below 100 μg/kgDM. During all the leaching experiments, only CIP, CBZ and IBP were detected. Experiments carried out on sludge showed that different sludge treatments can lead to different contaminant releases. Indeed, the dried anaerobic digested sludge and the composted sludge led to a better retention of CIP and CBZ as shown during batch and column experiments. Sludge thickening and composting led to a greater retention of IBP as shown in batch experiments. However, the sludge exhibited the same behavior in column experiments concerning IBP. In addition, CIP was neither detected in batch nor in column experiments carried out with soil-sludge mixtures whereas IBP and CBZ were either quantified or detected. In batch experiments IBP was quantified in leachates coming from soil-DS mixture and only detected in leachates of other mixtures. Under the same batch conditions, CBZ was quantified in each leachate with a lower level in the soil-C-DDS. In the column experiments, IBP was quantified in all soil-sludge mixtures as well as CBZ. In addition, column experiments with the non-contaminated soil showed that IBP can migrate in soil. But, a fraction of IBP seemed irreversibly sorbed to the soil. On the contrary, CIP showed no migration in laboratory column experiments. In lysimeter vessel under unsaturated conditions, CIP was not detected in leachates. IBP was quantified in only one leachate coming from the lysimeter filled with the soil-DS mixture and was also detected in some other leachates. CBZ was quantified in all leachates, the lowest concentration was found for the soil-compost mixture. These results confirmed what was already observed during batch and column experiments: CIP is highly retained in soils whereas IBP and CBZ can be mobilized. These results are also in accordance with results obtained on field-experiment where CBZ and IBP were detected at low frequency in the soil-leachates (2). According to the concentrations found in the raw and treated sludge, it seems that ibuprofen is preferentially released compared to carbamazepin and ciprofloxacin. Ciprofloxacin is highly retained in the soil. Ibuprofen release is nevertheless moderate. The releases of ciprofloxacin and carbamazepin are lower is the case of compost supply

Leaching and degradation of S-Metolachlor in undisturbed soil cores amended with organic wastes

International audienceOrganic waste (OW) reuse in agriculture is a common practice fostered by benefits in terms of waste recycling and crop production. However, OW amendments potentially affect the fate of pesticide spread on fields to protect the crops from pests and weeds. The influence of OW on the sorption, degradation, and leaching of pesticides is generally studied for each mechanism separately under artificial laboratory conditions. Our study aims at evaluating the balance of these mechanisms under more realistic conditions to clarify the influence of three common OW amendments on the fate, in soil, of the widely used herbicide S-Metolachlor. We performed leaching experiments in large undisturbed soil cores amended with raw sewage sludge, composted sludge, and digested pig slurry (digestate), respectively. We monitored S-Metolachlor and its two main metabolites MET-OA and MET-ESA in the leachates during a succession of 10 rainfall events over 126 days. We also quantified the remaining S-Metolachlor and metabolites in the soil at the end of the experiments. S-Metolachlor leaching didn't exceed 0.1% of the applied dose with or without OW amendment. Despite a soil organic carbon increase of 3 to 32%, OW amendments did not significantly affect the amount of S-Metolachlor that leached through the soil (0.01 to 0.1%) nor its transformation rate (6.0 to 8.6%). However, it affected the degradation pathways with an increase of MET-OA relative to MET-ESA formed after OW amendment (28 to 54%) compared to the controls (8%). Concentration of S- Metolachlor and metabolites in the leachates of all treatments greatly exceeded the regulatory limit for groundwater intended for human consumption in Europe. These high concentrations were probably the consequence of preferential macropore flow. Colloids had comparable levels in the leachates after S-Metolachlor application. Dissolved organic carbon was also comparable in the controls, digestate, and sludge treatments but was 65% higher in the compost-amended cores. These results, along with a great variability among replicates inherent to experiments performed under realistic conditions, partly explain the limited impact of OW on the transport of S-Metolachlor

A method to assess glyphosate, glufosinate and aminomethylphosphonic acid in soil and earthworms

International audienceA new sensitive and selective analytical methodology to quantify glyphosate (GLY), aminomethylphosphonic acid (AMPA), and glufosinate (GLU) in both soil and earthworms (Allolobophora chlorotica) was developed. The extraction and purification methods were optimized. The samples were extracted with various aqueous solutions (HNO3, H2O, KOH and borate buffer) and derivatized with 9-Fluorenylmethyl chloroformate (FMOCCl). To optimize the extraction step, a method to remove the excess FMOCCl was applied based on liquid-liquid extraction with diethyl ether. The purification of derivatized extracts was carried out using XLB solid phase extraction (SPE) cartridges before internal standard quantification by liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS). The elution step was optimized to obtain the best recoveries possible, which was with acidic methanol (1% formic acid) (67% for GLY, 70% for GLU and 65% for AMPA). The extraction and purification method followed by analysis of the two herbicides and AMPA in soils using LC/MS/MS determined limit of quantification (LOQ) values of 0.030mug g(-)(1) for GLY, 0.025mug g(-)(1) for AMPA and 0.020microg g(-)(1) for GLU . For earthworms, LOQ were 0.23mug g(-)(1) for GLY, 0.20mug g(-)(1) for AMPA and 0.12mug g(-)(1) for GLU. . The developed method was applied to determine these compounds in natural soils and earthworms

Impact of soil fertilization with organic amendments on the dissemination of antibiotic resistance in cultivated soils

National audienc

Effets d'apports répétés au champ de boues et de boues compostées sur les teneurs en résidus de médicaments dans les sols

National audienc