Abstract
Contamination of aquatic systems with pharmaceutical products represents a rising concern. The Kadicha river in Northern Lebanon is an illustrative example of a small Mediterranean river affected by rapid urbanization and population growth. This paper reports the first study on occurrence and ecological risk assessments on selected pharmaceuticals and their metabolites within the Kadicha river. For this purpose, surface water samples were collected over two sampling campaigns from twelve sites impacted by urban, rural, and mixed land uses (residential and agricultural zones) within the Kadicha river basin. Among the studied pharmaceuticals, six compounds (carbamazepine, diclofenac, acetaminophen, sulfamethoxazole, ofloxacin, and atenolol) were detected with detection frequencies and concentrations that vary according to the sampling sites. Carbamazepine was the most frequently detected compound and showed the highest concentrations (not detected-290 ng/L). The presence of pharmaceuticals carbamazepine, ofloxacin (not detected-190 ng/L), and atenolol (not detected-93 ng/L) was related to raw wastewater inputs in the water body, while the presence of sulfamethoxazole (not detected-23 ng/L) was associated with its usage in specific sites with livestock activity. Besides, the presence of acetaminophen (not detected-242 ng/L) and diclofenac (not detected-1055 ng/L) can be affected by their degradation properties in river waters. The highest concentrations were observed in the urbanized downstream area, while the lowest concentrations were within the rural upstream area. Thus, the urbanized downstream area presents the highest potential risks for aquatic species. Moreover, ofloxacin may pose high ecotoxicological risks in this watershed. The levels of contamination with pharmaceuticals do not exceed the concentrations reported in the literature. Furthermore, the levels of carbamazepine, diclofenac, and acetaminophen were more similar to sites receiving raw wastewaters, while the concentration levels of sulfamethoxazole, ofloxacin, and atenolol were more similar to sites receiving treated wastewaters. This paper highlights the need to collect and treat wastewater in this watershed to improve the situation for health and the environment. Monitoring programs on pharmaceutical compounds in Lebanese river waters are needed to better understand the pollution situation and make future public policies on water quality in Lebanon.