Background: The presence of pharmaceutical substances and their residual in water resources is an important environmental concern. Azithromycin, an antibiotic that is used for the treatment of infectious diseases, is a pollutant agent in the wastewater. The aim of this study was to investigate azithromycin degradation in aqueous solution through ultrasonic process in the presence of zinc oxide nanoparticles as catalysts.
Methods: Sonocatalytic experiments were performed at variable conditions including pH (3-8), temperature (20-60°C), time (3-21 minutes), catalyst dosage (0.25-2 g/L), hydrogen peroxide concentration (15-100 mg/L) and initial azithromycin concentration (10-100 mg/L).
Results: The optimum values for pH (3), temperature (40°C), time (15 minutes), catalyst dosage (1 g/L), H2O2 concentration (50 mg/L) and initial azithromycin concentration (20 mg/L) were determined. The highest degradation efficiency of 98.4% was achieved after 15 minutes of ultrasonic irradiation under optimum condition.
Conclusion: According to the results, ultrasonic irradiation is able to degrade azithromycin. In addition, ZnO and hydroxyl radical can successfully accelerate the reaction process in the shortest possible time.

Background: Human activities related to workshops in the cities contribute to the release of heavy metals into the environment, which pose serious risks to the environment and to human health. The aim of the present study was to evaluate the concentration of lead (Pb), iron (Fe), and manganese (Mn) in the pine trees and soil in various land uses of Birjand city, Iran.
Methods: The sampling stations were randomly selected from different land uses including parks, streets, carwashes, car repair shops, and car smooth shops in Birjand city. The pine trees (skin and leaves) and soil samples were collected from 15 stations located at different and uses in 2017. To determine the concentration of heavy metals, atomic absorption spectrometer (Contr AA 700) was used.
Results: It was revealed that the mean concentration of Pb, Fe and Mn in residential soil was 1.79, 419.39, and 30.76 mg/kg, respectively. Moreover, the Pb, Fe, and Mn concentration in pine skin and leaves was 0.63 – 0.18, 23.05–9.84, and 10.05–3.13 mg/kg, respectively. The geo-accumulation index (Igeo) mean of the study areas demonstrated a descending trend for Fe (16.31 mg/kg) Conclusion: According to the results, the soils of car repair and smooth shops as well as carwashes in Birjand are becoming polluted by Pb, Fe, and Mn. Although, it does not threaten the city ecosystem, but with passage of time, these measures will be accumulated due to the soil alkalinity and will reach critical levels.