Naproxen, ibuprofen, and diclofenac residues in river water, sediments and Eichhornia crassipes of Mbokodweni river in South Africa: An initial screening

Abstract

In the last 5 years, naproxen, ibuprofen and diclofenac have been the subject of investigation in the South African water resources. In this study, their occurrence in river water, sediments and aquatic plants was investigated. The concentrations of compounds detected in river water and sediments varied from 0.59 to 2.3 µg L⁻¹ and 0.2 to 9.2 ng g⁻¹, respectively. The partitioning coefficients (L kg⁻¹) for naproxen, ibuprofen and diclofenac varied from one sampling location to the other in ranges of 3.36–4, 1.3–1.9 and 0.13–0.91, respectively. This indicates that the fate of these pharmaceuticals can be influenced by the surrounding conditions such as climate and presence of other water pollutants as well as differences in physicochemical parameters. In the aquatic plant species (Eichhornia crassipes), the concentrations of target compounds varied in different parts of the plant material (roots, stems and leaves). Naproxen was the most abundant in Eichhornia crassipes, with the maximum concentration of 12.0 ng g⁻¹ found in leaves. In this initial assessment, we found no rational trend for the concentrations detected in various parts of Eichhornia crassipes, however, it is speculated that these pharmaceuticals diffuse from water into the roots of the aquatic plants and get translocated into the stem and leaves. Overall, the occurrence of naproxen, ibuprofen and diclofenac in river water, sediments and Eichhornia crassipes was observed, which is an indication that Eichhornia crassipes has the ability to reduce water pollution through the uptake of pharmaceuticals through plant roots.

Keywords:

• Eichhornia crassipes
• river water
• sediments
• pharmaceuticals
• solid-phase extraction
• high performance liquid chromatography

Additional information

Funding

This work is based on the research supported in part by the National Research Foundation of South Africa (Grant Numbers: 114415) and Durban University of Technology.