Ecological screening indicators of stress and risk for the Llobregat river water

Abstract

The objective of this article is to develop and apply several simple and rough indicators for river aquatic ecosystems assessment in order to screen potential chemical stressors. Several indicators, based on toxicity (PNEC) and on legislation levels (EQS) have been developed. All these indicators are ratios that were calculated by using public and private data of concentrations of a large list of compounds during a period of five years, including metals and organic compounds in the lower part of the Llobregat river basin at the intake of the drinking water treatment plant. Additionally, new campaigns were executed for increasing the information available on the presence of compounds not routinely analyzed, such as some other pesticides and pharmaceuticals. In the case of inorganic pollutants, the indicators obtained in this river section showed significant risk especially for zinc, but also for copper, nickel and barium. For organic pollutants, the pesticides terbuthylazine, diazinon, 2-methyl-4-chlorophenoxyacetic (MCPA), and in a few cases, chlorpyrifos and lindane, also showed indexes above the threshold. Among the pharmaceuticals, the antibiotics clarithromycin and ciprofloxacin were the only ones with risk indicators adverse to ecosystems. The specific values of the indexes obtained rely on the quantity and quality of the data available, so their interpretation should take into account that some values can be high due to the use of too conservative toxicological information.

Keywords: 5th percentile of the distribution; ACA; AF; BCF; CI; Catalan Water Agency; DGT; DWTP; EC(50); EQS; ERA; ES; Ecological risk assessment (ERA); Fluvial ecosystems; GIS; HC(5%); IRA; K(ow); LC; LC(50); LOEC; LOQ; MS/MS; Metals; NOEC; PEC; PNEC; Pesticides; Pharmaceutical compounds; SGAB; SPE; SSD; Sociedad General de Aguas de Barcelona; TU; WFD; WQI; Water Framework Directive; assessment factor; bioconcentration factor; confidence interval; diffusive gradient thin film; drinking water treatment plant; ecological risk assessment; electrospray; environmental quality standards; geographical information systems; integrated risk assessment; limit of quantification; liquid chromatography; lowest observed effect concentration; no observed effect concentration; octanol–water partition coefficient; predicted environmental concentration; predicted no effect concentration; solid phase extraction; species sensitivity distribution; tandem mass spectrometry; term half maximal effective concentration; term half maximal lethal concentration; toxicity units; water quality indexes.