A 900-year isotopic proxy rainfall record from Northeastern Botswana

SUPPLEMENTARY MATERIALS : Figure S1: Age-depth model.A high-resolution climate archive was reconstructed based on carbon isotope analysis and radiocarbon dating of the Chapman baobab in northeastern Botswana. The Chapman baobab, which exhibited an open ring-shaped structure composed of six stems, collapsed in January 2016 during an intense El Niño event. Two samples belonging to the oldest stems were investigated in order to obtain a proxy rainfall record, which provides insight into the precipitation regime over the last millennium, evincing centennial and decadal scale variability. The results indicate that the Medieval Warm Period was marked by relatively stable precipitation, whereas rainfall variability and drought frequency increased during the Little Ice Age. The investigated area has experienced both wetter and drier conditions in the past. The wettest conditions of the last millennium were registered before 1450 while the driest period occurred in 1835. For southern Africa, inter-annual rainfall variability is mainly associated with sea surface temperatures in the Agulhas Current core region, which determine the east–west displacement of tropical temperate troughs. Previous studies suggested that positive sea surface temperature anomalies in the Mozambique Channel led to an eastward movement of the troughs but the Chapman record demonstrates a westward displacement in the past, causing drought in northeastern South Africa and wetter conditions in the central part of southern Africa. The positive rainfall correlation with SST anomalies reversed after 1900, causing a gradual decrease in precipitation and confirming the current aridity trend for Botswana. The results contribute to a better understanding of the past climate of southern Africa for which paleoclimate reconstructions remain scarce.The Romanian Ministry of Research CNCS-UEFISCDI.https://www.mdpi.com/journal/forestsam2024Mammal Research InstituteSDG-15:Life on lan

Detection of volatile organic compounds in breath using thermal desorption electrospray ionization-ion mobility-mass spectrometry

A thermal desorption unit has been interfaced to an electrospray ionization-ion mobility-time-of-flight mass spectrometer. The interface was evaluated using a mixture of six model volatile organic compounds which showed detection limits of <1 ng sample loaded onto a thermal desorption tube packed with Tenax, equivalent to sampled concentrations of 4 μg L−1. Thermal desorption profiles were observed for all of the compounds, and ion mobility-mass spectrometry separations were used to resolve the probe compound responses from each other. The combination of temperature programmed thermal desorption and ion mobility improved the response of selected species against background ions. Analysis of breath samples resulted in the identification of breath metabolites, based on ion mobility and accurate mass measurement using siloxane peaks identified during the analysis as internal lockmasses

Hunting for Toxic Industrial Chemicals: Real-Time Detection of Carbon Disulfide Traces by Means of Ion Mobility Spectrometry

Sensitive real-time detection of vapors produced by toxic industrial chemicals (TICs) represents a stringent priority nowadays. Carbon disulfide (CS2) is such a chemical, being widely used in manufacturing synthetic textile fibers and as a solvent. CS2 is simultaneously a very reactive, highly flammable, irritant, corrosive, and highly toxic compound, affecting the central nervous system, cardiovascular system, eyes, kidneys, liver, skin, and reproductive system. This study was directed towards quick detection and quantification of CS2 in air, using time-of-flight ion mobility spectrometry (IMS); photoionization detection (PID) was also used as confirmatory technique. Results obtained indicated that IMS can detect CS2 at trace levels in air. The ion mobility spectrometric response was in the negative ion mode and presented one product ion, at a reduced ion mobility (K0) of 2.25 cm2 V&minus;1 s&minus;1. Our study demonstrated that by using a portable, commercial IMS system (model Mini IMS, I.U.T. GmbH Berlin Germany) one can easily measure CS2 at concentrations of 0.1 ppmv (0.3 mg m&minus;3) in the negative ion mode, which is below the lowest threshold value of 1 ppmv given for industrial hygiene. A limit of detection (LOD) of ca. 30 ppbv (0.1 mg m&minus;3) was also estimated

Sensing Precursors of Illegal Drugs—Rapid Detection of Acetic Anhydride Vapors at Trace Levels Using Photoionization Detection and Ion Mobility Spectrometry

Sensitive real-time detection of vapors produced by the precursors, reagents and solvents used in the illegal drugs manufacture represents a priority nowadays. Acetic anhydride (AA) is the key chemical used as acetylation agent in producing the illegal drugs heroin and methaqualone. This study was directed towards quick detection and quantification of AA in air, using two fast and very sensitive analytical techniques: photoionization detection (PID) and ion mobility spectrometry (IMS). Results obtained indicated that both PID and IMS can sense AA at ultra-trace levels in air, but while PID produces a non-selective response, IMS offers richer information. Ion mobility spectrometric response in the positive ion mode presented one product ion, at reduced ion mobility K0 of 1.89 cm2 V&minus;1 s&minus;1 (almost overlapped with positive reactant ion peak), while in the negative ion mode two well separated product ions, with K0 of 1.90 and 1.71 cm2 V&minus;1 s&minus;1, were noticed. Our study showed that by using a portable, commercial IMS system (model Mini IMS, I.U.T. GmbH Berlin) AA can be easily measured at concentrations of 0.05 ppmv (0.2 mg m&minus;3) in negative ion mode. Best selectivity and sensitivity of the IMS response were therefore achieved in the negative operation mode

Control of dopants / modifiers in differential mobility spectrometry using a piezoelectric injector

A piezoelectric injector has been interfaced to a differential mobility spectrometer to enable fast and reversible control of dopant/transport-gas modifier levels within the reaction region of the instrument. Operating at 1 Hz with optimised bipolar waveforms for the piezoelectric injector and gas flows within the injector, steady-state 2-butanol mass fluxes of 21 to 1230 ng min-1 and 1-bromohexane mass fluxes of 149 to 2644 ng min-1 were delivered to the differential mobility cell. Control of split-flow and transport-gas flow rates enabled rapid and flexible control of the dopant concentrations. The system was consistently reproducible with a relative standard deviation (RSD) of 7.9% at every mass- flux level studied. Stable responses were achieved between 3 to 5 seconds following a change in the control levels and no significant hysteresis effects were observed. In the positive mode it was possible to control the extent of formation protonated monomer and proton bound cluster ions, tentatively assigned to {C4H9OH(H2O)n}+ and {2C4H9OH(H2O)n}+ and similar control was possible in the negative mode where the concentration relationship for the formation of bromide clusters indicated the presence of multiple ionisation mechanisms. A dopant formulation for the simultaneous control of ions in both the positive and negative modes was demonstrated by the injection of a 50%/50% v/v solution of 2-butanol/1-bromohexane with mass fluxes of 2-butanol in the mixture of between 11 and 1161 ng min-1 and between 13 and 1325 ng min-1 for 1-bromohexane

Radiocarbon investigation of two old elms from Romania

Author Posting. © Studia Chemia, 2022. This article is posted here by permission of Studia Chemia for personal use, not for redistribution. The definitive version was published in Studia Universitatis Babes: Bolyai Chemia, 67(1), 245–256, https://doi.org/10.24193/subbchem.2022.1.16.The paper reports the AMS (accelerator mass spectrometry) radiocarbon investigation results of two superlative elms from Romana, the very large field elm of Calafat, with a wood volume of 85 m 3 , and the wych elm of Sadova. Two wood samples were extracted from each elm and were analysed by AMS radiocarbon. The oldest dated sample from the elm of Calafat had a radiocarbon date of 350 ± 19 BP, which corresponds to a calibrated age of 415 ± 25 years, while the oldest sample from the elm of Sadova had a radiocarbon date of 188 ± 24 BP, corresponding to a calibrated age of 260 ± 25 years. These values indicate high ages for the two elms, namely 430 ± 25 years or the elm of Calafat and 400 ± 25 years for the elm of Sadova.The research was funded by the Romanian Ministry of Education CNCS-UEFISCDI under grant PN-III-P4-ID-PCE-2020-2567, No. 145/2021

A 900-Year Isotopic Proxy Rainfall Record from Northeastern Botswana

A high-resolution climate archive was reconstructed based on carbon isotope analysis and radiocarbon dating of the Chapman baobab in northeastern Botswana. The Chapman baobab, which exhibited an open ring-shaped structure composed of six stems, collapsed in January 2016 during an intense El Niño event. Two samples belonging to the oldest stems were investigated in order to obtain a proxy rainfall record, which provides insight into the precipitation regime over the last millennium, evincing centennial and decadal scale variability. The results indicate that the Medieval Warm Period was marked by relatively stable precipitation, whereas rainfall variability and drought frequency increased during the Little Ice Age. The investigated area has experienced both wetter and drier conditions in the past. The wettest conditions of the last millennium were registered before 1450 while the driest period occurred in 1835. For southern Africa, inter-annual rainfall variability is mainly associated with sea surface temperatures in the Agulhas Current core region, which determine the east–west displacement of tropical temperate troughs. Previous studies suggested that positive sea surface temperature anomalies in the Mozambique Channel led to an eastward movement of the troughs but the Chapman record demonstrates a westward displacement in the past, causing drought in northeastern South Africa and wetter conditions in the central part of southern Africa. The positive rainfall correlation with SST anomalies reversed after 1900, causing a gradual decrease in precipitation and confirming the current aridity trend for Botswana. The results contribute to a better understanding of the past climate of southern Africa for which paleoclimate reconstructions remain scarce