River sediments’ monitoring: impact of tannery discharges

Abstract

Purpose – The tannery industry impacts strongly on water bodies due to the presence of chemical substances, such as chlorides, sulphates, chromium and other pollutants. This study has been carried out with a view to enhance the environmental compatibility of the Arzignano tannery district (northern Italy) which is the largest in Italy, by improving the quality of the Fratta-Gorzone River. Sediment quality, according to the driving forces-pressure-state-impact-response (DPSIR) scheme, has been developed as a significant impact indicator to be applied at basin level. The purpose of this paper is to discuss the above issues. Design/methodology/approach – Data were produced during institutional monitoring and control activities carried out by ARPAV (Veneto Region Environmental Prevention and Protection Agency) according to official methods. To define the environmental impacts on the river basin, a statistical assessment was performed on water and sediment quality data to establish the degree of correlation for the main pollutants along the river stem. Findings – In the basin considered, sediment quality presents high levels of contamination from heavy metals – in particular chromium (Cr) (III) – as well as organic pollutants. Investigation of the pressure sources revealed that the discharge from the Arzignano tannery district is the main source of Cr (III), according to background studies performed in the same area. Practical implications – The quality of river sediments must be improved in order to avoid the re-suspension/solubility of pollutants; dredged materials with high polluting substances must be managed with specific precautions in order to safeguard the environment. Originality/value – The river studied is currently the only significant water body in which sediment monitoring has been performed in the Veneto Region (Italy) since 2002. This study presents issues linked to the characterization of river sediment and the correlation between sediment quality and water pollution and prior and current pressure sources.