Medieval demise of a Himalayan giant summit induced by mega-landslide.

Despite numerous studies on Himalayan erosion, it is not known how the very high Himalayan peaks erode. Although valley floors are efficiently eroded by glaciers, the intensity of periglacial processes, which erode the headwalls extending from glacial cirques to crest lines, seems to decrease sharply with altitude. This contrast suggests that erosion is muted and much lower than regional rock uplift rates for the highest Himalayan peaks, raising questions about their long-term evolution.

Enhanced weathering input from South Asia to the Indian Ocean since the late Eocene.

Enhanced silicate weathering induced by the uplift of the Himalayan-Tibetan Plateau (HTP) has been considered as the major cause of pCO decline and Cenozoic cooling. However, this hypothesis remains to be validated, largely due to the lack of a reliable reconstruction of the HTP weathering flux. Here, we present a 37-million-year record of the difference in the seawater radiogenic neodymium isotopic composition (Δε) of Ocean Drilling Program (ODP) sites and Fe-Mn crusts between the northern and central Indian Ocean, which indicates the contribution of regional weathering input from the South Asian continent to the Indian Ocean.

Radon signature of CO flux constrains the depth of degassing: Furnas volcano (Azores, Portugal) versus Syabru-Bensi (Nepal Himalayas).

Substantial terrestrial gas emissions, such as carbon dioxide (CO), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO and radon-222 fluxes at the surface constrains the depth of degassing at two hydrothermal systems in geodynamically active contexts: Furnas Lake Fumarolic Field (FLFF, Azores, Portugal) with mantellic and volcano-magmatic CO, and Syabru-Bensi Hydrothermal System (SBHS, Central Nepal) with metamorphic CO.

Sustained wood burial in the Bengal Fan over the last 19 My.

The Ganges-Brahmaputra (G-B) River system transports over a billion tons of sediment every year from the Himalayan Mountains to the Bay of Bengal and has built the world's largest active sedimentary deposit, the Bengal Fan. High sedimentation rates drive exceptional organic matter preservation that represents a long-term sink for atmospheric CO While much attention has been paid to organic-rich fine sediments, coarse sediments have generally been overlooked as a locus of organic carbon (OC) burial. However, International Ocean Discovery Program Expedition 354 recently discovered abundant woody debris (millimeter- to centimeter-sized fragments) preserved within the coarse sediment layers of turbidite beds recovered from 6 marine drill sites along a transect across the Bengal Fan (∼8°N, ∼3,700-m water depth) with recovery spanning 19 My.

Persistent CO emissions and hydrothermal unrest following the 2015 earthquake in Nepal.

Fluid-earthquake interplay, as evidenced by aftershock distributions or earthquake-induced effects on near-surface aquifers, has suggested that earthquakes dynamically affect permeability of the Earth's crust. The connection between the mid-crust and the surface was further supported by instances of carbon dioxide (CO) emissions associated with seismic activity, so far only observed in magmatic context. Here we report spectacular non-volcanic CO emissions and hydrothermal disturbances at the front of the Nepal Himalayas following the deadly 25 April 2015 Gorkha earthquake (moment magnitude M = 7.

Occurrence of eight household micropollutants in urban wastewater and their fate in a wastewater treatment plant. Statistical evaluation.

The occurrence in urban wastewater of eight micropollutants (erythromycin, ibuprofen, 4-nonylphenol (4-NP), ofloxacin, sucralose, triclosan, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS)) originating from household activities and their fate in a biological wastewater treatment plant (WWTP) were investigated. Their concentrations were assessed in the liquid and solid phases (sewage particulate matter and wasted activated sludge (WAS)) by liquid chromatography-tandem mass spectrometry. The analysis of sewage from two different urban catchments connected to the WWTP showed a specific use of ofloxacin in the mixed catchment due to the presence of a hospital, and higher concentrations of sucralose in the residential area.

Root exudates modify bacterial diversity of phenanthrene degraders in PAH-polluted soil but not phenanthrene degradation rates.

To determine whether the diversity of phenanthrene-degrading bacteria in an aged polycyclic aromatic hydrocarbon (PAH) contaminated soil is affected by the addition of plant root exudates, DNA stable isotope probing (SIP) was used. Microcosms of soil with and without addition of ryegrass exudates and with ¹³C-labelled phenanthrene (PHE) were monitored over 12 days. PHE degradation was slightly delayed in the presence of added exudate after 4 days of incubation.

Recycling of graphite during Himalayan erosion: a geological stabilization of carbon in the crust.

At geological time scales, the role of continental erosion in the organic carbon (OC) cycle is determined by the balance between recent OC burial and petrogenic OC oxidation. Evaluating its net effect on the concentration of carbon dioxide and dioxygen in the atmosphere requires the fate of petrogenic OC to be assessed. Here, we report a multiscale (nanometer to micrometer) structural characterization of petrogenic OC in the Himalayan system.

Efficient organic carbon burial in the Bengal fan sustained by the Himalayan erosional system.

Continental erosion controls atmospheric carbon dioxide levels on geological timescales through silicate weathering, riverine transport and subsequent burial of organic carbon in oceanic sediments. The efficiency of organic carbon deposition in sedimentary basins is however limited by the organic carbon load capacity of the sediments and organic carbon oxidation in continental margins. At the global scale, previous studies have suggested that about 70 per cent of riverine organic carbon is returned to the atmosphere, such as in the Amazon basin.

Geochemical evidence for efficient aquifer isolation over geological timeframes.

Aquitards-layers of rock having low permeability-have been suggested as potential long-term reservoirs for toxic materials such as nuclear or chemical waste. But information about the isolation properties of aquitard layers is essential to evaluate whether they can indeed be used safely as reservoirs. Here we investigate the long-term mobility of groundwaters between two aquifers surrounding an aquitard layer in the eastern recharge area of the Paris basin, France, using helium isotopes as a geochemical tracer.