Abstract
The metal bioavailability concept is implemented in the Water Framework Directive (WFD) compliance assessment. The bioavailability assessment is usually performed by the application of user-friendly Biotic Ligand Models (BLMs), which require dissolved metal concentrations to be used with the “matching” data of the supporting physicochemical parameters of dissolved organic carbon (DOC), pH and Cadissolved. Many national surface water monitoring networks do not have sufficient matching data records, especially for DOC. In this study, different approaches for dealing with the missing DOC data are presented: substitution using historical data; the appropriate percentile of DOC concentrations; and combinations of the two. The applicability of the three following proposed substitution approaches is verified by comparison with the available matching data: (i) calculations from available TOC data; (ii) the 25th percentile of the joint Bulgarian monitoring network DOC data (measured and calculated by TOC); and (iii) the 25th percentile of the calculated DOC from the matching TOC data for the investigated surface water body (SWB). The application of user-friendly BLMs (BIO-MET, M-BAT and PNEC Pro) to 13 surface water bodies (3 reservoirs and 10 rivers) in the Bulgarian surface waters monitoring network outlines that the suitability of the substitution approaches decreases in order: DOC calculated by TOC > the use of the 25th percentile of the data for respective SWB > the use of the 25th percentile of the Bulgarian monitoring network data. Additionally, BIO-MET is the most appropriate tool for the bioavailability assessment of Cu, Zn and Pb in Bulgarian surface water bodies.
Highlights
The determination of metal species and their bioavailability depends crucially on Dissolved Organic Matter (DOM)
2021), M-BAT and PNEC Pro, data for the concentrations of pH, Dissolved Organic Carbon (DOC), Total Organic Carbon (TOC) and Cadissolved were obtained by the open data portal of the Bulgarian
The Bulgarian Environmental Agency surface water monitoring programme revealed a total of 1829 measurement results for DOC for all monitored surface water bodies since 2010 and 13,234 measurement results for dissolved Fe
Summary
The determination of metal species and their bioavailability depends crucially on Dissolved Organic Matter (DOM). The presence of DOM is specified as a Dissolved Organic Carbon (DOC) concentration, contrary to Natural Organic Matter (NOM), which is a collective organic component of water. The organic carbon results of unfiltered samples are reported as Total Organic Carbon (TOC) and samples filtered through a 0.45 μm filter are reported as DOC. Both results equal the mass of carbon present in the mixture of organic compounds in the raw water/filtrate [1]. DOC mainly comprises humic substances of natural origin, which is formed as a result of the breakdown of plant and animal tissues by chemical and biological processes or from anthropogenic sources [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
