Improvement of Sensitivity of the Lonizing Method For Radon Determination by lntegrated Current

采用积分电流电离法测氡结果表明；当氡气剂量很低时，在给定时间内将十分微弱的电流积分，大大地提高了测定的灵敏度，可测得剂量为1bQ以下的氧气，与常用的fd-125氡钍分析仪的比较实验数据相对误差不超过5%.The experimental results of Rn determination by the ionizing method with integrated ciruit are presented.The sensitivity of Rn determination could be greatly improved by integration of weakly ionizing current at very low concentrations of Rn and within the given experimental period.Experimental results indicated that sensitivity would be 1 Bq dose of Rn.Relative error was less than 5% in comparison with that of the FD-125 Rn analyzor

The Ionizing Measurement of Radon Escaped From the Underground Water

将氧气引入电离室，测定其微电流，可以直接测定地下水逸出气氡的浓度，实现自动记录。为地下水氧测定提供新的途径。该文着重介绍应用电离法测氧的各组实验及数据。When Radon is introduced into the ionizing cell,the micro-current can be mea-sured,so the Radon concentration can be measured directly and recorded automatically,This is a newmethod For measuring the Radon escaped From the underground water.In this paper,we present someexperiments and results of the Radon s measurement by the way of ionization

EXPERIMENTAL STUDY ON THE ESCAPED RADON GAS FROM THE HIGH TEMPERATURE TERMAL WELL

本文通过在漳州龙师1-#井开展的逸出气氡观测实验研究,认为逸出气氡作为新的地震前兆观测项目是可行的,可以进行平行样观测,同时可得到rn_气/rn_水比值,作为研究地下流体前兆的一个新的参数。并对应用电离法测量逸出气氡的连续自记观测技术进行了预研究试验。In this paper the authors propose that it is practical to apply the escaped Radon gas as a new observational item of seismic precursors by means of the experimental study on the escaped Radon gas From Longshi #1 well in Zhangzhou, Fujian Province.Authors have conducted the observation of parallel samples and obtained the ratio of Radon (gas) to Radon (water), which can be used as a new parameter to study the precursor of ground liquids.The authors also studied the continuous selF-recording technique by using the ionization method to measure the Radon gas

Weathering Characteristics of Microplastics of Low Density Polyethylene Film in the Coastal Environment of the Yellow River Estuary

【Objective】Microplastic pollution has become a global environmental issue that has caused widespread concern. Coastal zone is a region of land-ocean interaction under the dual impacts of global climate change and human activities. It is also an important sink for microplastics in the environment. However, by far little attention has been paid to long-term weathering characteristics of microplastics in coastal environments. In this study, microplastics of low density polyethylene(LDPE)film, which were commonly found in the coastal environments of the Yellow Sea and the Bohai Sea, were selected as the object for test in exploring long-term weathering characteristics of the microplastics in different coastal environments, including supratidal, intertidal and subtidal zones at the Yellow River Estuary. The aim of this study is to lay down a scientific basis for clarifying fates and effects of microplastics in the coastal environments. 【Method】Microplastics of LDPE film were left in the tidal zones for exposure to the coastal environment for 12 and 18 months. At the end of the each exposure period, they were retrieved for analysis of surface morphology, chemical functional groups(carbonyl index)and density with scanning electron microscopy, Fourier transform infrared spectrometry, and pycnometry. Weathering degree of the microplastics was characterized. 【Result】 Results show that after 18 months of exposure in the field, colonies of microorganisms were observed on the surface of the microplastics in all the zones and so were significant weathering characteristics. The microplastics in the supratidal zone exhibited the highest degree of cracking. Carbonyl groups were also observed on the surface of the microplastics regardless of where they were in, and in terms of carbonyl index of the microplastics, the three zones displayed an order of supratidal zone (0.28-0.81) > intertidal zone (0.18-0.22) > subtidal zone (0.16-0.20). The microplastics did not show much spatio-temporal variation in density. However, having been subjected to ultrasonic cleaning for removal of surface attachments, the microplastics exposed aboveground at the supratidal zone for 18 months were by (0.850.02 g·cm~(-3)) significantly lower than the untreated ones (0.930.03 g·cm~(-3)) in density.【Conclusion】The dynamic changes in morphological characteristics, chemical functional groups (carbonyl index) and density of the microplastics of LDPE film indicate that weathering degree of the microplastics varying with the tidal zone shows a declining order of supratidal zone > intertidal zone > subtidal zone, and the microplastics in the supratidal zone varied sharply with time in weathering characteristics. The microplastics in the coastal environment are subjected to physical, chemical and biological weathering, such as light, friction, chemical oxidation, and biodegradation. Among them, light-triggered photochemical oxidation may contribute the most to the weathering of microplastics. In the future, more attention should be paid to the research on potential environmental effects and fate of microplastics as affected by the complex environmental factors in the coastal environment

Surface properties and changes in morphology of microplastics exposed in-situ to Chinese coastal wetlands

Coastal wetlands are key areas of accumulation of microplastics. However, until now only a few studies have focused on the surface properties and morphological changes in microplastics in the real coastal wetland environment. Here, two typical biogeographic coastal soils, the Yellow River Estuary salt marsh wetland in the temperate zone and the Beibu Bay mangrove wetland in the subtropical zone, were selected for study. Polystyrene foams and polyethylene films were used and exposed within two coastal wetlands sites through in situ soil burial (underground exposure) and surface placement (above-ground exposure). The samples were sampled after 6, 12, 18 and 24 months of exposure to reveal the characteristics of the surface properties and morphological changes in microplastics in typical wetlands from the southern and northern biogeographic coastal zones. The surface morphology, microstructures and attached materials were observed using scanning electron microscopy using an energy dispersive spectrometer. Surface properties of the microplastics, i.e. the surface roughness, specific surface area, pore size distribution, functional groups and hydrophobicity, were analyzed by using atomic force microscopy, a surface area analyzer, a mercury porosimeter, Fourier transform infrared spectrometry and a contact angle meter. The surface morphology of the polystyrene foams in the Beibu Bay mangrove wetland exhibited more pits and holes than those in the Yellow River Estuary salt marsh wetland. The polystyrene foams exposed aboveground in the Beibu Bay mangrove wetland showed embrittlement and exfoliation after 18 months, while those exposed underground did not show such features. The specific surface areas of the polystyrene foams and the polyethylene films in the Yellow River Estuary salt marsh wetland were higher than those in the Beibu Bay mangrove wetland. The pore distributions on the surfaces of the two microplastic types mainly comprised macropores and mesopores. However, the porosity of the polyethylene film in the Yellow River Estuary salt marsh wetland was slightly higher than in the Beibu Bay mangrove wetland. The porosities in both regions were higher than in the original control samples. In terms of carbonyl index, rates of change in the Yellow River Estuary salt marsh wetland were higher than those in the Beibu Bay mangrove wetland. The surface hydrophobicity of the polyethylene film in the two regions declined with increasing exposure time. The changes in surface morphology of the polystyrene foams were more rapid than those in the polyethylene films, but the degree of change in specific surface area of the polyethylene films was greater than in the case of the polystyrene foams. It can be concluded that the surface properties and changes in morphology of microplastics in the coastal soil environment are related to multiple factors including the types and conditions of the wetlands, types of microplastics, exposure mode and exposure time. However, the specific mechanisms of these surface changes require further study. In summary, this study provides a scientific basis for research on the chemical processes of the micro-interfaces on the microplastic surfaces and environmental behavior and risk assessment of microplastics in the Chinese coastal zone

Prediction of Energy Resolution in the JUNO Experiment

International audienceThis paper presents the energy resolution study in the JUNO experiment, incorporating the latest knowledge acquired during the detector construction phase. The determination of neutrino mass ordering in JUNO requires an exceptional energy resolution better than 3% at 1 MeV. To achieve this ambitious goal, significant efforts have been undertaken in the design and production of the key components of the JUNO detector. Various factors affecting the detection of inverse beta decay signals have an impact on the energy resolution, extending beyond the statistical fluctuations of the detected number of photons, such as the properties of liquid scintillator, performance of photomultiplier tubes, and the energy reconstruction algorithm. To account for these effects, a full JUNO simulation and reconstruction approach is employed. This enables the modeling of all relevant effects and the evaluation of associated inputs to accurately estimate the energy resolution. The study reveals an energy resolution of 2.95% at 1 MeV. Furthermore, the study assesses the contribution of major effects to the overall energy resolution budget. This analysis serves as a reference for interpreting future measurements of energy resolution during JUNO data taking. Moreover, it provides a guideline in comprehending the energy resolution characteristics of liquid scintillator-based detectors