Determination of guidance values for closed landfill gas emissions

International audienceIn order to promote active landfill gas collection and treatment or natural attenuation, it is necessary to identify trigger values concerning landfill gas emissions in the preliminary stage of a risk assessment. The determination of these values is the first goal of a work which includes a large regulation review and the study of a generic inhalation exposure scenario for the most common reuse of French Municipal Solid Waste (MSW) landfill surface, namely a recreational area without residential buildings. The health risk levels of this scenario are lower than the usual levels and enable to determine trigger values for methane production rate. These results and the methane oxidation rate in the landfill cover allow for the determination of residual methane surface emission rates. The combination of these parameters with on-site specific measurements enables the promotion of natural attenuation or active landfill gas treatment

Sensor implementation on Eulerian Obs.

Implementation of pH sensor on Eulerian observations in the Mediterranean Sea (DYFAMED site

Abrupt episode of mid-Cretaceous ocean acidification triggered by massive volcanism

Large igneous province volcanic activity during the mid-Cretaceous approximately 94.5 million years ago triggered a global-scale episode of reduced marine oxygen levels known as Oceanic Anoxic Event 2. It has been hypothesized that this geologically rapid degassing of volcanic carbon dioxide altered seawater carbonate chemistry, affecting marine ecosystems, geochemical cycles, and sedimentation. Here, we report on two sites drilled by the International Ocean Discovery Program offshore of southwest Australia that exhibit clear evidence for suppressed pelagic carbonate sedimentation in the form of a stratigraphic interval barren of carbonate, recording ocean acidification during the event. We then use the osmium isotopic composition of bulk sediments to directly link this protracted ~600- kiloyear shoaling of the marine calcite compensation depth to the onset of volcanic activity. This decrease in marine pH was prolonged by biogeochemical feedbacks in highly productive regions that elevated heterotrophic respiration of carbon dioxide to the water column. A compilation of mid- Cretaceous marine stratigraphic records reveals a contemporaneous decrease of sedimentary carbonate content at continental slope sites globally. Thus, we contend that changes in marine carbonate chemistry are a primary ecological stress and important consequence of rapid emission of carbon dioxide during many large igneous province eruptions in the geologic past

Hypoxia-induced modulation of apoptosis and BCL-2 family proteins in different cancer cell types

Hypoxia plays an important role in the resistance of tumour cells to chemotherapy. However, the exact mechanisms underlying this process are not well understood. Moreover, according to the cell lines, hypoxia differently influences cell death. The study of the effects of hypoxia on the apoptosis induced by 5 chemotherapeutic drugs in 7 cancer cell types showed that hypoxia generally inhibited the drug-induced apoptosis. In most cases, the effect of hypoxia was the same for all the drugs in one cell type. The expression profile of 93 genes involved in apoptosis as well as the protein level of BCL-2 family proteins were then investigated. In HepG2 cells that are strongly protected against cell death by hypoxia, hypoxia decreased the abundance of nearly all the pro-apoptotic BCL-2 family proteins while none of them are decreased in A549 cells that are not protected against cell death by hypoxia. In HepG2 cells, hypoxia decreased NOXA and BAD abundance and modified the electrophoretic mobility of BIM(EL). BIM and NOXA are important mediators of etoposide-induced cell death in HepG2 cells and the hypoxia-induced modification of these proteins abundance or post-translational modifications partly account for chemoresistance. Finally, the modulation of the abundance and/or of the post-translational modifications of most proteins of the BCL-2 family by hypoxia involves p53-dependent and -independent pathways and is cell type-dependent. A better understanding of these cell-to-cell variations is crucial in order to overcome hypoxia-induced resistance and to ameliorate cancer therapy

Evolution of the Southwest Australian Rifted Continental Margin During Breakup of East Gondwana: Results from IODP Expedition 369

International Ocean Discovery Program Expedition 369 drilled four sites on the southwestern Australian continental margin, in the deep water Mentelle Basin (MB) and on the neighboring Naturaliste Plateau (NP). The drillsites are located on continental crust that continued rifting after seafloor spreading began further north on the Perth Abyssal Plain (PAP) between magnetochrons M11r and M11n (133‐132 Ma), ending when spreading began west of the NP between chrons M5n and M3n (126‐124 Ma). Drilling recovered the first in‐situ samples of basalt flows overlying the breakup unconformity on the NP, establishing a magnetostratigraphically constrained eruption age of >131‐133 Ma and confirming a minimal late Valanginian age for the breakup unconformity (coeval with the onset of PAP seafloor spreading). Petrogenetic modeling indicates the basalts were generated by 25% melting at 1.5 GPa and a potential temperature of 1380‐1410 °C, consistent with proximity of the Kerguelen plume during breakup. Benthic foraminiferal fossils indicate that the NP remained at upper bathyal or shallower depths during the last 6 Myr of rifting and for 3‐5 Myr after breakup between India and Australia. The limited subsidence is attributed to heat from the nearby Kerguelen plume and PAP spreading ridge. The margin subsided to middle bathyal depths by Albian time and to lower bathyal (NP) or greater (MB) depths by late Paleogene time. Periods of rapid sedimentation accompanied a westward jump of the PAP spreading ridge (108 Ma), rifting on the southern margin (100‐84 Ma), and opening of the southern seaway between Australia and Antarctica (60‐47 Ma)