Abstract
European legislative framework supports a multidisciplinary strategy of environmental monitoring because the environment is a complex system of abiotic and biotic interactions, and it should not be studied and protected by looking at one single aspect. The resulting heterogeneous data request to be carefully processed, and the application of Weight of Evidence (WOE) approaches is, thereby, an integrated validated tool. In this perspective, the present study aims to: (i). apply a specific model (Sediqualsoft) based on the WOE approach for processing multidisciplinary data related to four Lines Of Scientific Evidence (LOEs: chemical analyses, ecotoxicological bioassays, bioaccumulation tests and biomarkers) regarding sediments from an area of the Adriatic Sea; (ii). evaluate the usefulness of this specific integrated approach to estimate the potential environmental hazard due to the presence of gas production platforms respect to the traditional approach of sediment chemical characterization. This latter recognized a more contaminated area within 100 m of the platforms in which the Sediqualsoft model showed the presence of a chemical hazard, ranging from moderate to severe, and identified the contaminants (e.g., some metals, benzo(a)pyrene and acenaphthene) most responsible for it. A significant hazard also appeared in some of the sampled stations by analyzing the LOEs dedicated to the biological responses. The choice of different reference values (regulatory limits, threshold values or concentrations measured in the control area) influenced only the chemical hazard but not the overall integration with other LOEs, showing a moderate hazard for the majority of stations. Here, the concentrations measured in a control area are firstly proposed as possible reference values in Sediqualsoft model applications; this could be of particular relevance when Sediment Quality Guidelines are not available for all the measured substances. Moreover, the limitations of a conventional pass-to-fail approach or worst-case scenario were overcoming interpreting whole chemical and ecotoxicological results. All data analyzed and discussed confirm Sediqualsoft as a suitable tool for processing environmental data, including those first processed here on a monitoring scenario of gas platforms that discharge Produced Water into the sea.
Highlights
Different types of investigations are performed in environmental monitoring plans, from chemical to ecotoxicological and ecological analyses, their independent interpretation is often misleading and not representative of the real environmental impacts due to contamination
Where Environmental Quality Standards (EQS) are not available, concentrations measured for some contaminants may be compared to values measured in the control area or to threshold values below which adverse effects rarely occur as Effects Range Low (ERL) and Threshold Effect Level (TEL) [2,3]
We evaluated sediment contamination by determining the concentrations of the main contaminants of the production process (trace metals, total hydrocarbons, volatile hydrocarbons and polycyclic aromatic hydrocarbons (PAHs)) and comparing the measured values with EQSs or, alternatively, with the values of the control area
Summary
Different types of investigations are performed in environmental monitoring plans, from chemical to ecotoxicological and ecological analyses, their independent interpretation is often misleading and not representative of the real environmental impacts due to contamination. The comparison between measured concentrations and regulatory thresholds is functional for the assessment of environmental chemical quality, but it does not take directly into account biological/ecological responses and potential toxic effects of chemical mixtures [4]. Changes in the structure of biological communities are indicators of potential natural and anthropic impacts and, one of the factors affecting environmental quality assessment [6]. The Sediment Quality Triad was the first WOE approach to integrate three LOEs: chemical analysis, toxicity tests and ecological analysis [8]. The triad allowed potential biological and ecological impacts to be related to contamination through a qualitative integrated assessment of the environmental data (e.g., low—adverse effects unlikely, medium—adverse effects may or may not occur, high—adverse effects likely). Sediment is a deposit of organic matter and contaminants, a refuge for benthic organisms and bacterial communities; in addition to its ecological value, it has a his-
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