# Retention of the Antibiotic Cofruoxime onto Agricultural and Forest Soils
###### Abstract  
Antibiotics in wastewater, sewage sludge, manures, and slurries constitute a risk for the environment when spread on soils. This work studies the adsorption and desorption of the antibiotic cefruoxime (CFX) in 23 agricultural and forest soils, using batch-type experiments. Our results show that the adsorption values were between 40.75 and 99.57% in the agricultural soils, while the range was lower (from 74.57 to 93.46%) in forest soils. Among the Freundlich, Langmuir, and Linear models, the Freundlich equation shows the best fit for the adsorption results. In addition, agricultural soils with higher pH are the ones that present the highest adsorption. Further confirmation of the influence of pH on adsorption is given by the fact that [PERSON]'s K\({}_{F}\) parameter and the Linear model K\({}_{d}\) parameter shows a positive correlation with pH and with the exchangeable Ca and Mg values, which are known to affect the charges of the soil colloids and the formation of cationic bridges between adsorbents and adsorbate. In addition, [PERSON]'s \(n\) parameter shows a positive and significant correlation with the organic matter content, related to the high adsorption taking place on forest soils despite their pH! 5. Regarding desorption, in most cases, it is lower than 1%, which indicates that CFX is adsorbed in a rather irreversible way onto these soils. Overall, these results can be considered relevant regarding their potential impact on environmental quality and public health. adsorption; desorption; emerging pollutants; soils +
Footnote †: journal:ment, and the subsequent potential impact has been causing increasing concerns in recent years, as previously occurred for some inorganic pollutants [6; 7]. In fact, [PERSON] et al. [8] indicate that since the beginning of the 21 st century a growing number of studies has revealed the presence of a wide range of persistent pharmaceuticals in soil and water, and its relevance has been confirmed [9]. The main entry of human-medicine antibiotics into the environment takes place through wastewater and sewage sludge, after domestic use. In fact, it has been reported that the direct application of wastewater in irrigation, or the application of sewage sludge as fertilizer in agricultural soils, can be the main source of antimicrobials to the edaphic environment [10; 11; 12; 13], as wastewater treatment plants usually do not eliminate these pollutants [14; 15; 16; 17]. Excessive concentrations of these drugs in the soil could affect food quality, the safety of crop production, and the health of the environment, bearing in mind that these contaminants move through environmental compartments and the food chain, especially after being absorbed by plants [18; 19; 20]. Once the antibiotics reach soils, they are subjected to different physicochemical and biological processes in the soil-water system, mainly adsorption/desorption, degradation, transportation, and uptake by crops, depending on the properties of the antibiotic, the characteristics of the soil, and climatic conditions. The magnitude of each of these processes will strongly determine the fate and persistence of these compounds in the environment [21; 22]. Among antibiotics, cefuroxime (CFX) is a compound belonging to the cephalospor group, and it has become one of the most consumed worldwide [23]. It is frequently used to treat diseases like pneumonia, otitis, sinusitis, and urinary tract infection [24]. Regarding its presence in the environment, in a study dealing with antibiotics in treated wastewater, [PERSON] et al. [25] found that CFX was the one with the highest concentrations, reaching around 6.6 \(\upmu\)g L\({}^{-1}\). Moreover, regarding CFX in the environment, [PERSON] et al. [26] found that the application of manure increased the levels of this and other antibiotics in greenhouse soils. Furthermore, as regards its effects on microbiota in the environment, [PERSON] et al.