Changes in Southern Ocean hydrography may have played an important role in the Middle Pleistocene Transition (MPT), particularly through their impact on ocean circulation and atmospheric CO2 ...concentrations. Here we present foraminiferal Mg/Ca and δ18O results for the subsurface dwelling planktonic foraminifer Neogloboquadrina pachyderma (sinistral) at the Ocean Drilling Program (ODP) Site 1090. Results are used to reconstruct upper ocean temperatures and derive seawater δ18O in the Subantarctic Atlantic Ocean during the MPT. The new records indicate that, starting at ∼1250ka, glacial temperatures and local (ice volume corrected) seawater δ18O in the upper water column of the Subantarctic Atlantic Ocean decreased, pointing to cooler (∼2°C) and fresher (∼0.4‰) conditions than in the preceding glacial stages. These upper ocean hydrographic changes broadly coincide with the increase in the power of the 100ky glacial–interglacial cycle in both records and with a shift towards decreased deep ventilation in the glacial Southern Ocean. Our finding suggests that an increase in Southern Ocean stratification, driven by the observed freshening of the upper water column, may have reduced the exchange of carbon between the deep Southern Ocean and the atmosphere during glacial stages. This process may have contributed, in combination with other mechanisms, to lower glacial atmospheric CO2 concentrations during the MPT.
► Cooling and freshening of the Subantarctic upper ocean during the MPT. ► Glacial Southern Ocean (SO) stratification during the MPT. ► SO physical and biological interactions, with implications on G/I pCO2 cycling.
Arctic sea ice coverage is shrinking in response to global climate change and summer ice-free conditions in the Arctic Ocean are predicted by the end of the century. The validity of this prediction ...could potentially be tested through the reconstruction of the climate of the Pliocene epoch (5.33-2.58 million years ago), an analogue of a future warmer Earth. Here we show that, in the Eurasian sector of the Arctic Ocean, ice-free conditions prevailed in the early Pliocene until sea ice expanded from the central Arctic Ocean for the first time ca. 4 million years ago. Amplified by a rise in topography in several regions of the Arctic and enhanced freshening of the Arctic Ocean, sea ice expanded progressively in response to positive ice-albedo feedback mechanisms. Sea ice reached its modern winter maximum extension for the first time during the culmination of the Northern Hemisphere glaciation, ca. 2.6 million years ago.
We report a case of a nine-year-old boy with clinical evidence of foreign body (FB) aspiration with 3 months of delay in diagnosis. The bronchoscopy found soft tissue FB with surrounding inflamed ...granulation tissue at the entrance to the lateral segmental bronchus. Repeated attempts to remove the FB with flexible forceps were unsuccessful due to friable FB and granulation tissue. Ablation of the granulation tissue using nitrous oxide cryotherapy was then successfully performed and the distal and organic FB was extracted. Early diagnosis is important for minimizing granulation tissue development which complicates FB removal. Cryotherapy with a flexible bronchoscope is an option if organic FB cannot be removed using conventional bronchoscopic instrumentation.
Archaeal tetraether membrane lipids span the whole membrane width and present two C40 isoprenoid chains bound by two glycerol groups (or one glycerol and calditol). These lipids confer stability and ...maintain the membrane fluidity in mesophile to extremophile environments, making them very attractive for biotechnological applications. The isoprenoid lipid composition in archaeal membranes varies with temperature, which has placed these lipids in the focus of paleo-climatological studies for over a decade. Non-hydroxylated isoprenoid archaeal lipids are typically used as paleo-thermometry proxies, but recently identified hydroxylated (OH) derivatives have also been proposed as temperature proxies. The relative abundance of hydroxylated lipids increases at lower temperatures, but the physiological function of the OH moiety remains unknown. Here we present molecular dynamics simulations of membranes formed by the acyclic glycerol-dialkyl-glycerol-tetraether caldarchaeol (GDGT-0), the most widespread archaeal core lipid, and its mono-hydroxylated variant (OH-GDGT-0) to better understand the physico-chemical properties conferred to the membrane by this additional moiety. The molecular dynamics simulations indicate that the additional OH group forms hydrogen bonds mainly with the sugar moieties of neighbouring lipids and with water molecules, effectively increasing the size of the polar headgroups. The hydroxylation also introduces local disorder that propagates along the entire alkyl chains, resulting in a slightly more fluid membrane. These changes would help to maintain trans-membrane transport in cold environments, explaining why the relative abundance of hydroxylated Archaea lipids increases at lower temperatures. The in silico approach aids to understand the underlying physiological mechanisms behind the hydroxylated lipid based paleo-thermometer recently proposed.
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•We studied the effects of hydroxylation of GDGT-0 lipids by molecular dynamics.•OH moieties bulge out from the core lipid and extend the polar head group region.•The OH addition introduces local disorder that propagates along the core lipid.•Free cavities are displaced towards the inner part of the membrane.•Permeation of small solutes would be facilitated at low temperature.
Oil extraction activities in the Northern Peruvian Amazon have generated a long-standing socio-environmental conflict between oil companies, governmental authorities and indigenous communities, ...partly derived from the discharge of produced waters containing high amounts of heavy metals and hydrocarbons. To assess the impact of produced waters discharges we conducted a meta-analysis of 2951 river water and 652 produced water chemical analyses from governmental institutions and oil companies reports, collected in four Amazonian river basins (Marañon, Tigre, Corrientes and Pastaza) and their tributaries. Produced water discharges had much higher concentrations of chloride, barium, cadmium and lead than are typically found in fresh waters, resulting in the widespread contamination of the natural water courses. A significant number of water samples had levels of cadmium, barium, hexavalent chromium and lead that did not meet Peruvian and international water standards. Our study shows that spillage of produced water in Peruvian Amazon rivers placed at risk indigenous population and wildlife during several decades. Furthermore, the impact of such activities in the headwaters of the Amazon extended well beyond the boundaries of oil concessions and national borders, which should be taken into consideration when evaluating large scale anthropogenic impacts in the Amazon.
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•Meta-analysis to assess impacts of oil exploration in the headwaters of the Amazon.•Spillage of produced waters contaminated rivers between 1987 and 2013.•Widespread contamination by chloride, cadmium and barium.•Local population and wildlife exposed to hazardous levels of heavy metals.
By means of a meta-analyses of governmental reports we have established that the long term spillage of oil produced waters led to widespread contamination in the headwater of the Amazon.
Urban green installations are extensively promoted to increase sustainable and accessible food production and simultaneously improve the environmental performance and liveability of city buildings. ...In addition to the multiple benefits of plant retrofitting, these installations may lead to a consistent increase in biogenic volatile organic compounds (BVOCs) in the urban environment, especially indoors. Accordingly, health concerns could limit the implementation of building-integrated agriculture. In a building-integrated rooftop greenhouse (i-RTG), throughout the whole hydroponic cycle, green bean emissions were dynamically collected in a static enclosure. Four representative BVOCs, α-pinene (monoterpene), β-caryophyllene (sesquiterpene), linalool (oxygenated monoterpene) and cis-3-hexenol (LOX derivate), were investigated in the samples collected from two equivalent sections of a static enclosure, one empty and one occupied by the i-RTG plants, to estimate the volatile emission factor (EF). Throughout the season, extremely variable BVOC levels between 0.04 and 5.36 ppb were found with occasional but not significant (P > 0.05) variations between the two sections. The highest emission rates were observed during plant vegetative development, with EFs equivalent to 78.97, 75.85 and 51.34 ng g−1 h−1 for cis-3-hexenol, α-pinene, and linalool, respectively; at plant maturity, all volatiles were either close to the LLOQ (lowest limit of quantitation) or not detected. Consistent with previous studies significant relationships (r ≥ 0.92; P < 0.05) were individuated within volatiles and temperature and relative humidity of the sections. However, correlations were all negative and were mainly attributed to the relevant effect of the enclosure on the final sampling conditions. Overall, levels found were at least 15 folds lower than the given Risk and LCI values of the EU-LCI protocol for indoor environments, suggesting low BVOC exposure in the i-RTG. Statistical outcomes demonstrated the applicability of the static enclosure technique for fast BVOC emissions survey inside green retrofitted spaces. However, providing high sampling performance over entire BVOCs collection is recommended to reduce sampling error and incorrect estimation of the emissions.
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•Unknown levels of indoor BVOC emissions are investigated in a building integrated rooftop greenhouse (i-RTG).•Dynamic sampling in static enclosure is proposed for fast BVOC emissions determination in indoor systems.•Higher BVOC emissions are expected along full vegetative development.•Enclosing conditions may affect true emissions estimation.•Indicative BVOC levels provided are below the lowest concentrations of interest reported in official tables.
Hyperbaric oxygen therapy, the administration of 100% oxygen at pressures > 1 atm, is believed to promote wound healing by increasing angiogenesis and collagen synthesis. To our knowledge, this ...treatment modality has never been described in patients with tracheal radionecrosis. Here, we report the case of a 55-year-old man diagnosed with stage IIIB lung adenocarcinoma who was treated with chemotherapy and concomitant external intensity-modulated radiotherapy involving the left lung and mediastinum. Nine months later, he presented with neck pain, cough with mucopurulent sputum, and fever. A PET-CT scan revealed a fissure in the posterior wall of the left upper trachea. Flexible bronchoscopy showed a tracheal ulceration with a small left posterior wall fissure that extended into the mediastinum. To our knowledge, this is the first report in the literature that suggests that treatment with hyperbaric oxygen therapy, local debridement, and antibiotics is a feasible and successful management option for patients with complicated tracheal radionecrosis.
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