Development and application of an innovative expert decision support system to manage sediments and to assess environmental risk in freshwater ecosystems

With the aim of supporting decision makers to manage contamination in freshwater environments, an innovative expert decision support system (EDSS) was developed. The EDSS was applied in a sediment quality assessment along the Bormida river (NW, Italy) which has been heavily contaminated by an upstream industrial site for more than a century. Sampling sites were classified by means of comparing chemical concentrations with effect-based target values (threshold and probable effect concentrations). The level of each contaminant and the combined toxic pressure were used to rank sites into three categories: (i) uncontaminated (8 sites), (ii) mildly contaminated (4) and (iii) heavily contaminated (19). In heavily contaminated sediments, an environmental risk index (EnvRI) was determined by means of integrating chemical data with ecotoxicological and ecological parameters (triad approach). In addition a sediment risk index (SedRI) was computed from combining chemical and ecotoxicological data. Eight sites exhibited EnvRI values ≥ 0.25, the safety threshold level (range of EnvRI values: 0.14–0.31) whereas SedRI exceeded the safety threshold level at 6 sites (range of SedRI values: 0.16–0.36). At sites classified as mildly contaminated, sublethal biomarkers were integrated with chemical data into a biological vulnerability index (BVI), which exceeded the safety threshold level at one site (BVI value: 0.28). Finally, potential human risk was assessed in selected stations (11 sites) by integrating genotoxicity biomarkers (GTI index falling in the range 0.00–0.53). General conclusions drawn from the EDSS data include: (i) in sites classified as heavily contaminated, only a few exhibited some significant, yet limited, effects on biodiversity; (ii) restrictions in re-using sediments from heavily contaminated sites found little support in ecotoxicological data; (iii) in the majority of the sites classified as mildly contaminated, tested organisms exhibited low response levels; (iv) preliminary results on genotoxicity biomarkers indicate possible negative consequences for humans if exposed to river sediments from target areas.     

The environmental potential of reuse: an application to used books

Reuse is generally considered to have environmental benefits, but it has not yet been widely adopted in environmental policy or strategy. In this paper, a simple model of second-hand markets is explored with a case study of used books that illustrates the behavior of the model and shows that such a model is consistent with the data. Three questions of the dynamics of reuse are addressed: (1) If it becomes easier to buy and sell used goods (via Internet markets or other means), by how much will sales of used goods increase? (2) When sales of used goods increase, by how much will sales of new goods decrease? (3) When is reuse better than recycling? Expanding from the case study, the model is used to examine how reuse affects the consumption of new goods, and the relative merits of reuse versus recycling. When the used goods market is small, the ratio of the price of used and new goods, an observable quantity, is approximately equal to the fractional decrease in sales of new goods that will result from increased sales of used goods. A formulation of the environmental impact of reuse and recycling is developed that includes the market impact of reuse. Illustrating this formulation for books with a simplified analysis, reuse of books through sales in a second-hand market is estimated to save more than twice as much energy, with considerable uncertainty, than making books from recycled paper. The formulation provides a basis for identifying products and markets for which reuse can be an effective environmental strategy.     

Using stated preference methods to assess environmental impacts of forest biomass power plants in Portugal

As a renewable energy source, the use of forest biomass for electricity generation is advantageous in comparison with fossil fuels; however, the activity of forest biomass power plants causes adverse impacts, affecting particularly neighbouring communities. The main objective of this study is to estimate the effects of the activity of forest biomass power plants on the welfare of two groups of stakeholders, namely local residents and the general population. To this end, we apply two stated preference methods: contingent valuation and discrete choice experiments, respectively. The former method was applied to estimate the minimum compensation residents of neighbouring communities of two forest biomass power plants in Portugal would be willing to accept. The latter method was applied among the general population to estimate their willingness to pay to avoid specific environmental impacts. The results show that the presence of the selected facilities affects individuals’ well-being. On the other hand, in the discrete choice experiments conducted among the general population all impacts considered were valued, in particular odour and fauna and flora impacts. The results of this study stress the importance of performing an equity analysis of the welfare effects on different groups of stakeholders from the installation of forest biomass power plants, as their effects on welfare are location and impact specific. Policy makers should take into account the views of all stakeholders either directly or indirectly involved when deciding crucial issues regarding the sitting of new forest biomass power plants, in order to achieve an efficient and equitable outcome.     

Sorption-desorption tests to assess the risk derived from metal contamination in mineral and organic soils

We obtained the sorption isotherms of Cd, Cu, Pb and Zn from seven soils with contrasting properties, including mineral and organic soils. The distribution coefficients (Kd) were determined from batch tests in a solution that simulated the soil solution cationic composition. The Kd values of the target metals varied greatly depending on soil type and initial metal concentration. Sorption isotherms were fitted to Freundlich and Langmuir models, and derived parameters were correlated to soil properties through the construction of a correlation matrix and application of Principal Component Analysis. The batch Kd showed a satisfactory agreement with the Kd obtained from field-contaminated soils. The sorption tests were complemented with the estimation of the reversibility of metal sorption by the application of an extraction test. The extraction yields, which did not relate to the initial metal concentration, depended on the metal-soil combination, and showed no correlation to batch Kd values. The risk derived from a contamination event was estimated through the quantification of a Retention Factor, defined as the ratio of the Kd versus the extraction yield. Results showed that this was an excellent index to highlight which metal and soil represent the most vulnerable scenarios after a contamination event.     

Aquivalence revisited--new model formulation and application to assess environmental fate of ionic pharmaceuticals in Hamilton Harbour, Lake Ontario

A model formulation based on "aquivalence", as defined in terms of activity is presented to estimate the multimedia fate of ionizing chemicals. The aquivalence approach is analogous to fugacity but aquivalence is applicable to neutral and ionizing compounds, and has been applied previously to speciating chemicals, notably metals. The new aquivalence-based mass-balance model treats ionizing organic compounds that exist as interconverting neutral and ionic species which are subject to fate processes at differing rates. The model is illustrated by application to four ionizing pharmaceuticals in Hamilton Harbour, Lake Ontario. At the system pH of 7.9-8.5, ibuprofen, gemfibrozil, and naproxen are expected to be almost entirely ionic and triclosan split between ionic and neutral forms. Measured seasonal surface water concentrations, which were 2-10 times lower in the late summer and fall than during spring, were used to solve for unknown values of chemical half-life in the water column due to degradation (photo- and bio-) of the ionizing and neutral forms and secondarily, ionic sorption coefficients of the ionizing forms. Model estimates of half-lives in the habour's water ranged from 11 to 77, 11 to 147 and 10 to 37 for ionic ibuprofen, gemfibrozil, and naproxen, respectively; and 4-22 days and 2-9 days for ionic and neutral triclosan, respectively, with the shortest half-lives in spring and the longest in summer.     

A biological and geochemical integrated approach to assess the environmental quality of a coastal lagoon (Ravenna, Italy)

The assessment of the environmental quality of coastal lagoons is rather difficult as their intrinsic high variability limits the power of analytical chemistry and ecotoxicological approaches. Aim of the present work was to integrate geochemical and biological data which were simultaneously collected from the Pialassa Baiona lagoon (Ravenna, Italy), and evaluate the usefulness of a biomonitoring strategy based on sentinel organisms and biomarkers. Geochemical analysis on suspended, surface, and subsurface sediments were performed at five different sites of the lagoon; moreover the heavy metal bioaccumulation and a battery of biomarkers was evaluated in Mytilus galloprovincialis transplanted in the same sites. Heavy metals appeared to be diffused throughout the lagoon reaching higher levels in the southernmost sites, and mainly concentrated in suspended sediments. Lysosome membrane stability, neutral lipid and lipofuscin accumulation, and metallothionein levels in mussels indicated the development of a stress syndrome in animals exposed to the polluted sites.     

A new hazard index of complex mixtures integrates bioconcentration and toxicity to refine the environmental risk assessment of effluents

A new methodology to evaluate the overall environmental hazard of unknown mixtures, based on bioconcentration potential and toxicity, was developed using a combination of two methodologies: 1) the estimation of the octanol-water partition coefficient (K(ow)) using reverse-phase high performance liquid chromatography (RP-HPLC) and 2) the toxicity identification evaluation (TIE). Forty seven compounds with known K(ow) and different molecular structures where used for the calibration of the log K(ow) in relation to the retention time in reverse-phase high performance liquid chromatography (RP-HPLC). A linear regression with an R(2)=0.81 and an sd=0.69 was established between log K(ow) and RP-HPLC retention time. This K(ow) estimation method was furthermore validated using seven additional compounds, showing acceptable estimations of the log K(ow) of unknown substances. Two different mixtures were tested, one containing 3,4 Dichloroaniline, Diazinon and 4-Nonylphenol and another one containing a mixture of 16 pesticides. Both mixtures were first tested as a whole effluent and then fractionated and tested, using a miniaturized Daphnia magna test. An equation is presented, that combines both methodologies and establishes a relative hazard index RHI, ranging from 1 to 10 for any particular mixture of chemicals. The results show how the method presented can refine the security factors that could be included in the environmental risk assessment of effluents in the future.     

Derivation of predicted no effect concentrations (PNEC) for marine environmental risk assessment: application of different approaches to the model contaminant Linear Alkylbenzene Sulphonates (LAS) in a site-specific environment

Four sediment-dwelling marine organisms were exposed to sediments spiked with increasing concentrations of Linear Alkylbenzene Sulphonate (LAS). The selected endpoint mortality was reported daily and acute LC(50) (96 h), as well as final LC(10) values were calculated for the derivation of environmentally safe predicted no effect concentrations (PNEC) for the sediment compartment. PNECs were estimated by both application of assessment factors (AF) and the equilibrium partitioning method (EPM) as proposed by the EU TGD. Finally, environmental risk assessment in a site-specific environment, the Sancti Petri Channel, South Iberian Peninsula, was carried out at three different sampling stations with known environmental LAS concentrations. PNECs obtained by the assessment factor approach with acute toxicity data were one to two orders of magnitude lower than those from the equilibrium partitioning method. On the other hand, when applying lower AFs to the estimated LC(10) values, the PNECs obtained by both approaches were more similar. Environmental risk assessment carried out with the estimated PNECs in a site specific environment with known sediment LAS concentrations revealed that PNECs obtained with acute toxicity data were over conservative whereas those obtained with AF=10 on LC(10) data and EPM produced more realistic results in accordance with field observations carried out in the study area.