Monitoring and quantitative evaluation of Faraday cup deterioration in a thermal ionization mass spectrometer using multidynamic analyses of laboratory standards

Accurate and precise isotopic ratio determinations using multi-collector (MC) mass spectrometers rely on accurate cross-calibration and long-term stability of the efficiencies of the multiple detectors. Isotopic analyses at the part per million (ppm) level of precision, which are commonly carried out with a thermal ionization mass spectrometer (TIMS) equipped with arrays of several Faraday cups, are the most sensitive to detector efficiency variations. Quantitative characterization of the Faraday cup efficiency change (also known as Faraday cup deterioration) during instrument usage can assist the analyst in making decisions about the replacement or cleaning of Faraday cups and in making corrections to the measured isotopic ratios, which are both essential to sustain the high measurement accuracy and long-term reproducibility of MC-TIMS. In this study, we present a method to quantitatively and continuously track the deterioration degrees of individual Faraday cups on MC-TIMS. The advantage of this method, compared to the previous ones, is that it uses only the results of regular repetitive analyses of laboratory standards, and no additional, specially designed experiments are required. Using this method, we monitored the performance of Triton Plus MC-TIMS at the Research School of Earth Sciences, the Australian National University, during a 6 month Sr isotope analytical session, and observed significant Faraday cup deterioration up to 150 ppm. The cups that have received the most abundant Sr atom deposition during the analytical session deteriorated the most, confirming that the accumulation of measured elements is the likely cause of changing Faraday cup efficiencies. The response of the cup efficiency to the accumulation of Sr atoms in the cup is complex and non-linear, and differs between cups in magnitude and direction, suggesting that Faraday cup deterioration is not a simple univariate function of the accumulation of measured elements.This project was funded by the Australian Research Council grant DP190100002 “The history of accretion in our Solar System”

Spatial and temporal characteristics of dryness/wetness for grapevine in the Northeast of China between 1981-2020

The Northeast of China has a marked continental monsoon climate characterized by dry and wet hazards that have destructive impacts on wine grape yields and quality. The purpose of this study was to analyze the spatiotemporal characteristics of dryness/wetness of grapevines in the wine region of northeast China from 1981 to 2020. The Crop Water Surplus and Deficit Index (CWSDI) was used to characterize the dryness/wetness using meteorological data collected at 15 meteorological stations located in or near the wine region of northeast China from 1981–2020. Results showed that the multi-year average precipitation could satisfy the water requirement of grapevine with the average CWSDI of 43% (Bud burst), 35% (Shoot growth), 40% (Flowering), 73% (Berry development), 24% (Maturation) and 56% (Full growing stage) respectively for grapevine. Most growing stages experienced a wetting trend and varied discontinuously with the abrupt change in years. The drought-stricken areas were smaller than wet-stricken areas for each growing stage, especially for berry development and full growing stages. The drought and wet characteristics were stage-specific during the grapevine growth period. The precipitation, CWSDI, wet frequency, and wet risk increased from northwest to southeast for each growing stage, while crop evapotranspiration (ETc), drought frequency and drought risk showed the opposite characteristics. The drought risk was lower than wet risk in the Northeast wine region. These results can be used to develop strategies for mitigating and adapting dryness/wetness events in the wine regions of northeast China

A method to estimate the pre-eruptive water content of basalts: Application to the Wudalianchi-Erkeshan-Keluo volcanic field, Northeastern China

Water plays an important role in the generation and evolution of volcanic systems. However, the direct measurement of the pre-eruption water content of subaerial volcanic rocks is difficult, because of the degassing during magma ascent. In this study, we developed a method to calculate the pre-eruption water content of the basalts from the Cenozoic Wudalianchi-Erkeshan-Keluo (WEK) potassic volcanic field, Northeastern China, and investigated their mantle source. A water-insensitive clinopyroxene-melt thermobarometer and a water-sensitive silica activity thermobarometer were applied to these basalts. Two pressure-temperature (P-T) paths of the ascending magma were calculated using these two independent thermobarometers, with a similar P-T slope but clear offset. By adjusting the water content used in the calculation, the difference between the two P-T paths was minimized, and the water content of the WEK melts was estimated to be 4.5 ± 1.2 wt% at a pressure range of 10.1-13.5 kbar, corresponding to depths of 37-47 km. Degassing modeling shows that during the magma ascent from below the Moho to near the surface, CO2 was predominantly degassed, while the melt H2O content kept stable. Significant H2O degassing occurred until the magma ascended to 5-2 kbar. The silica activity P-T estimates of the most primary WEK samples suggest that the magmas were generated by the melting of convective mantle, which was probably facilitated by a wet upwelling plume from the mantle transition zone. The high water content found in the WEK basalts is similar to the recent reports on Phanerozoic intraplate large igneous provinces (LIPs) and supports the presence of hydrated deep mantle reservoirs as one possible source of the LIPs.This research was financially supported by the National Natural Science Foundation of China (grant number 41630205), the National Key R&D Program of China (2017YFC0601302) and National Student’s Platform for Innovation and Entrepreneurship Training Program of China (grant number 201511001041). Y.D. thanks “Tan Siu Lin Overseas Exchange Endowment for Undergraduates” for providing financial support for the trip and presentation of this research in the 2016 Goldschmidt conference

Catalytic co-pyrolysis of cellulosic ethanol–processing residue with high-density polyethylene over biomass bottom ash catalyst

In this study, the bagasse ash (BA) from biorefinery process was recovered and used as a catalyst in the co-pyrolysis of solid residue from second-generation bioethanol plant with high-density polyethylene (HDPE). The co-pyrolytic behaviors were studied using thermogravimetric analyzer at three heating rates of 10, 20, and 40 K min−1. The synergistic effects between BA and HDPE and their co-pyrolysis kinetics were investigated using two model-free methods: Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). The pyrolysis products were determined by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) as well. The results indicated that the addition of BA could increase the production yield. The average apparent active energy (Ea) of co-pyrolysis was 171.3 kJ mol−1 from KAS and 174 kJ mol−1 from FWO, which were lower than that for catalyst-free pyrolysis (174.8 kJ mol−1 from KAS and 177.3 kJ mol−1 from FWO). The novel co-pyrolysis process showed great potential in improving both the economic and environment sides of the second-generation biorefineries