Passive samplers provide a better prediction of PAH bioaccumulation in earthworms and plant roots than exhaustive, mild solvent, and cyclodextrin extractions

A number of extraction methods have been developed to assess polycyclic aromatic hydrocarbon (PAH) bioavailability in soils. As these methods are rarely tested in a comparative manner, against different test organisms, and using field-contaminated soils, it is unclear which method gives the most accurate measure of the actual soil ecosystem exposure. In this study, PAH bioavailability was assessed in ten field-contaminated soils by using exhaustive acetone/hexane extractions, mild solvent (butanol) extractions, cyclodextrin extractions, and two passive sampling methods; solid phase micro extraction (SPME) and polyoxymethylene solid phase extraction (POM-SPE). Results were compared to actual PAH bioaccumulation in earthworms (Eisenia fetida) and rye grass (Lolium multiflorum) roots. Exhaustive, mild solvent and cyclodextrin extractions consistently overpredicted biotic concentrations by a factor of 10-10 000 and therefore seem inappropriate for predicting PAH bioaccumulation in field contaminated soils. In contrast, passive samplers generally predicted PAH concentrations in earthworms within a factor of 10, although correlations between predicted and measured concentrations were considerably scattered. The same applied to the plant data, where passive samplers also tended to underpredict root concentrations. These results indicate the potential of passive samplers to predict PAH bioaccumulation, yet call for comparative studies between passive samplers and further research on plant bioavailability

Passive samplers provide a better prediction of PAH bioaccumulation in earthworms and plant roots than exhaustive, mild solvent, and cyclodextrin extractions

A number of extraction methods have been developed to assess polycyclic aromatic hydrocarbon (PAH) bioavailability in soils. As these methods are rarely tested in a comparative manner, against different test organisms, and using field-contaminated soils, it is unclear which method gives the most accurate measure of the actual soil ecosystem exposure. In this study, PAH bioavailability was assessed in ten field-contaminated soils by using exhaustive acetone/hexane extractions, mild solvent (butanol) extractions, cyclodextrin extractions, and two passive sampling methods; solid phase micro extraction (SPME) and polyoxymethylene solid phase extraction (POM-SPE). Results were compared to actual PAH bioaccumulation in earthworms (Eisenia fetida) and rye grass (Lolium multiflorum) roots. Exhaustive, mild solvent and cyclodextrin extractions consistently overpredicted biotic concentrations by a factor of 10-10 000 and therefore seem inappropriate for predicting PAH bioaccumulation in field contaminated soils. In contrast, passive samplers generally predicted PAH concentrations in earthworms within a factor of 10, although correlations between predicted and measured concentrations were considerably scattered. The same applied to the plant data, where passive samplers also tended to underpredict root concentrations. These results indicate the potential of passive samplers to predict PAH bioaccumulation, yet call for comparative studies between passive samplers and further research on plant bioavailability

Is sustainability certification for biochar the answer to environmental risks?

Biochar has the potential to make a major contribution to the mitigation of climate change, and enhancement of plant production. However, in order for biochar to fulfill this promise, the industry and regulating bodies must take steps to manage potential environmental threats and address negative perceptions. The potential threats to the sustainability of biochar systems, at each stage of the biochar life cycle, were reviewed. We propose that a sustainability framework for biochar could be adapted from existing frameworks developed for bioenergy. Sustainable land use policies, combined with effective regulation of biochar production facilities and incentives for efficient utilization of energy, and improved knowledge of biochar impacts on ecosystem health and productivity could provide a strong framework for the development of a robust sustainable biochar industry. Sustainability certification could be introduced to provide confidence to consumers that sustainable practices have been employed along the production chain, particularly where biochar is traded internationally

XIPE

XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrally-spatially-resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics. Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective area larger than one XMM mirror but with a low weight. The payload is compatible with the fairing of the Vega launcher. XIPE is designed as an observatory for X-ray astronomers with 75 % of the time dedicated to a Guest Observer competitive program and it is organized as a consortium across Europe with main contributions from Italy, Germany, Spain, United Kingdom, Poland, Sweden.Peer reviewe