A comparison of DEMETRA individual QSARs with an index for evaluation of uncertainty

Quantitative structure-activity relationships (QSARs) urgently need to be applied in regulatory programs. Many QSAR models can predict the effect of a wide range of substances to different endpoints, particularly in the case of ecotoxicity, but it is difficult to choose the most appropriate model on the basis of the requirements of the application. During the EC-funded project DEMETRA (www.demetra-tox.net) a huge number of QSAR models have been developed for the prediction of different ecotoxicological endpoints. DEMETRA individual models on rainbow trout LC50 after 96 h, water flea LC50 after 48 h and honey bee LD50 after 48 h have been used as a QSAR database to test the advantages of a new index for evaluating model uncertainty. This index takes into consideration the number of outliers (weighted on the total number of compounds) and their root mean square error. Application on the DEMETRA QSAR database indicated that the index can identify the models with the best performance with regard to outliers, and can be used, together with other classical statistical measures (e.g., the squared correlation coefficient), to support the evaluation of QSAR models.     

Novel two-step vapor-phase synthesis of UV–Vis light active Fe2O3/WO3 nanocomposites for phenol degradation

Supported Fe₂O₃/WO₃ nanocomposites were fabricated by an original vapor phase approach, involving the chemical vapor deposition (CVD) of Fe₂O₃ on Ti sheets and the subsequent radio frequency (RF)-sputtering of WO₃. Particular attention was dedicated to the control of the W/Fe ratio, in order to tailor the composition of the resulting materials. The target systems were analyzed by the joint use of complementary techniques, that is, X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and optical absorption spectroscopy. The results showed the uniform decoration of α-Fe₂O₃ (hematite) globular particles by tiny WO₃ aggregates, whose content could be controlled by modulations of the sole sputtering time. The photocatalytic degradation of phenol in the liquid phase was selected as a test reaction for a preliminary investigation of the system behavior in wastewater treatment applications. The system activity under both UV and Vis light illumination may open doors for further material optimization in view of real-world end-uses.

     

Plant growth promotion by inoculation with selected bacterial strains versus mineral soil supplements

In the process of remediation of mine sites, the establishment of a vegetation cover is one of the most important tasks. This study tests two different approaches to manipulate soil properties in order to facilitate plant growth. Mine waste from Ingurtosu, Sardinia, Italy rich in silt, clay, and heavy metals like Cd, Cu, and Zn was used in a series of greenhouse experiments. Bacteria with putative beneficial properties for plant growth were isolated from this substrate, propagated and consortia of ten strains were used to inoculate the substrate. Alternatively, sand and volcanic clay were added. On these treated and untreated soils, seeds of Helianthus annuus, of the native Euphorbia pithyusa, and of the grasses Agrostis capillaris, Deschampsia flexuosa and Festuca rubra were germinated, and the growth of the seedlings was monitored. The added bacteria established well under all experimental conditions and reduced the extractability of most metals. In association with H. annuus, E. pithyusa and D. flexuosa bacteria improved microbial activity and functional diversity of the original soil. Their effect on plant growth, however, was ambiguous and usually negative. The addition of sand and volcanic clay, on the other hand, had a positive effect on all plant species except E. pithyusa. Especially the grasses experienced a significant benefit. The effects of a double treatment with both bacteria and sand and volcanic clay were rather negative. It is concluded that the addition of mechanical support has great potential to boost revegetation of mining sites though it is comparatively expensive. The possibilities offered by the inoculation of bacteria, on the other hand, appear rather limited.     

Ecotoxicological effects of sediments from Mar Piccolo,South Italy: toxicity testing with organisms from different trophic levels

The Mar Piccolo of Taranto (Ionian Sea, Southern Italy) is a semi-enclosed and strongly polluted basin. For decades, it has been subjected to different anthropogenic impacts. These stressors caused severe sediments contamination with high concentration of different pollutants (PAHs, PCB, heavy metals). In order to assess the current status of sediments contamination, an ecotoxicological investigation combined with chemical analysis (heavy metals, PAH, and PCB) has been performed. In order to derive ecologically relevant conclusions, a multiorganisms and multiend-points approach has been applied, exposing organisms from different trophic levels to elutriate and whole sediment. The battery of bioassays consists of a microalgal growth inhibition test (Dunaliella tertiolecta), acute and sublethal assays (end-points: mortality, immobilization and swimming speed alteration) on crustaceans larvae and juveniles, and rotifers (Amphibalanus amphitrite, Artemia salina, Corophium insidiosum and Brachionus plicatilis), and embryotoxicity test on echinoderms (Paracentrotus lividus). Considering the high levels of sediment contamination highlighted from chemical analysis, an unexpected very low toxic effect was observed, even considering the sublethal end-point (larval swimming speed alteration). The results of this study suggest a very complex contaminants dynamic in the Mar Piccolo sediments that, despite a strong level of contamination, seems to not affect in a proportional manner the biological compartment.     

Scenarios of change in the realized climatic niche of mountain carnivores and ungulates

Mountains are among the natural systems most affected by climate change, and mountain mammals are considered particularly imperiled, given their high degree of specialization to narrow tolerance bands of environmental conditions. Climate change mitigation policies, such as the Paris Agreement, are essential to stem climate change impacts on natural systems. But how significant is the Paris Agreement to the survival of mountain mammals? We investigated how alternative emission scenarios may determine change in the realized climatic niche of mountain carnivores and ungulates in 2050. We based our predictions of future change in species niches based on how species have responded to past environmental changes, focusing on the probabilities of niche shrink and niche stability. We found that achieving the Paris Agreement's commitments would substantially reduce climate instability for mountain species. Specifically, limiting global warming to below 1.5°C would reduce the probability of niche shrinkage by 4% compared with a high-emission scenario. Globally, carnivores showed greater niche shrinkage than ungulates, whereas ungulates were more likely to shift their niches (i.e., face a level of climate change that allows adaptation). Twenty-three species threatened by climate change according to the IUCN Red List had greater niche contraction than other species we analyzed (3% higher on average). We therefore argue that climate mitigation policies must be coupled with rapid species-specific conservation intervention and sustainable land-use policies to avoid high risk of loss of already vulnerable species.     

Design considerations for financing a national trust to advance the deployment of geologic CO2 storage and motivate best practices

This paper explores how the widely held public policy view of the evolution of the risk profile associated with geologic carbon dioxide (CO₂) storage profoundly influences the public policy dialogue about how to best address the long-term risk profile for geologic storage. Evidence emerging from research and pilot scale field demonstrations of CO₂ storage demonstrates that, with proper site characterization and sound operating practices, retention of stored CO₂ will increase with time thus invalidating the premise of an ever growing risk. The authors focus on key issues of fit, interplay, and scalability associated with the ability of a trust fund funded by a hypothetical $1 per tonCO₂ tipping fee for each ton of CO₂ stored in the United States under WRE450 and WRE550 climate policies to manage such risks in an economically efficient and environmentally effective manner. The authors conclude there is no intrinsic value – in terms of risk management or risk reduction – in creating a trust fund predicated solely on collecting a universally applied tipping fee that does not take into account site-specific risk profiles. If left to grow unchecked, a trust fund that is predicated on a constant stream of payments unrelated to each contributing site's risk profile could result in the accumulation of hundreds of billions to more than a trillion dollars contributing to significant opportunity cost of capital. Further, rather than mitigating the financial consequences of long-term CCS risks, this analysis suggests a blanket $1 per tonCO₂ tipping fee, if combined with a concomitant limitation of liability may increase the probability and frequency of long-term risk by eliminating financial incentives for sound operating behavior and site selection criteria—contribute to moral hazard. At a minimum, effective use of a trust fund requires: (1) strong oversight regarding site selection and fund management, and (2) a clear process by which the fund is periodically valued and funds collected are mapped to the risk profile of the pool of covered CCS sites. Without appropriate checks and balances, there is no a priori reason to believe that the amount of funds held in trust will map to the actual amount of funds needed to address long-term care expenses and delimited compensatory damages. For this reason, the authors conclude that financing a trust fund or other risk management instrument should be based on a site delimited estimate of potential future expected financial consequences rather than on the random adoption of a fixed funding stream, e.g., a blanket $1 per ton, because it “sounds” reasonable.     

A multi-disciplinary framework to monetize financial consequences arising from CCS projects and motivate effective financial responsibility

Carbon dioxide capture and storage (CCS) holds promise as a safe and effective approach for addressing climate change. However, concern about potential “liability” associated with CCS often is cited as a significant barrier to project deployment. The authors contend that, in this context, the term “liability” is poorly defined and conflates concerns about the uncertainty in the timing and magnitude of potential damages with the need for financial responsibility for long-term stewardship of certified closed sites. This paper offers an analytic framework drawn from damages estimation methodologies used in comparable contexts and incorporates risk-based probabilistic modeling to assist stakeholders in evaluating the potential environmental, human health and financial consequences of CCS projects. Application of the proposed framework will achieve four distinct objectives. First, the outputs of the analyses – monetized damages estimates for adverse impact scenarios coupled with expected loss calculations that reflect scenario probabilities and identify the statistical range of possible outcomes, including “most likely” loss estimates – will help interested stakeholders consider the viability of various investment and financial risk management strategies. Second, the results can be used to develop or negotiate financial assurance instruments for analyzed projects. Third, the results will inform the public policy debate regarding the degree and magnitude of potential financial consequences resulting over the long-term, beyond an established post-closure period. And, fourth, while the detailed conceptual framework, resulting models, impact calculations and valuation analyses may be applied on a site-by-site basis, the site-specific results could be pooled to assess regional and national implications of various risk mitigation and financial risk management policies.     

Integration of biological responses from a suite of bioassays for the Venice Lagoon (Italy) through sediment toxicity index - Part A: Development and comparison of two methodological approaches

Marine and coastal quality assessment, based on test batteries involving a wide array of endpoints, organisms and test matrices, needs for setting up toxicity indices that integrate multiple toxicological measures for decision-making processes and that classify the continuous toxicity response into discrete categories according to the European Water Framework Directive.Two toxicity indices were developed for the lagoon environment such as the Venice Lagoon. Stepwise procedure included: the construction of a database that identified test-matrix pairs (indicators); the selection of a minimum number of ecotoxicological indicators, called toxicological core metrics (CMs-tox) on the basis of specific criteria; the development of toxicity scores for each CM-tox; the integration of the CMs-tox into two indices, the Toxicity Effect Index (TEI), based on the transformation of Toxic Unit (TU) data that were integrated as logarithmic sum, and the Weighted Average Toxicity Index (WATI), starting from toxicity classes integrated as weighted mean. Results from the indices are compared; advantages and drawbacks of both approaches are discussed.