The release of radon in active fault zones is a sustained radioactive pollution source of the atmospheric environment. The species, concentration and flux of radon emitted in soil gas in active fault zones in the Capital of China were investigated by in-situ field measurements. Two main species of radon discharging from soil gas in active fault zones were identified, including radon diffused and dispersed from permeable soil, and upwelling from faults. Higher concentrations and flux of radon from faults were observed in the Bohai Bay Basin due to the accumulated uranium in the sandstone reservoirs and higher permeability of the strata and bed rocks. Increased radon released by strong earthquakes persists, with the max flux of 334.56 mBq m⁻² s⁻¹ observed in FN (Fengnan district) located at the epicenter of the 28 July, 1976 Tangshan M_S 7.8 earthquake. The level of radon released in 8 of 22 locations within the Basin and Range Province (to the west of Taihangshan piedmont fault Zone) reached level 2, and 13 of 14 locations within the Bohai Bay Basin reached levels 2–4, according to the Chinese Code (GB 50325–2001, 2006). Corresponding protective and safety measures should be in place to protect the health of nearby residents, due to their exposure to radon emitted from the faults. Also, the concentration of radon in active fault zones should be investigated to assess the possible risk, before land-use is planned.

Since the discovery of superconductivity in boron-doped diamond with a critical temperature (T_C) near 4 K, great interest has been attracted in hard superconductors such as transition-metal nitrides and carbides. Here we report the new discovery of superconductivity in polycrystalline hexagonal ε-NbN synthesized at high pressure and high temperature. Direct magnetization and electrical resistivity measurements demonstrate that the superconductivity in bulk polycrystalline hexagonal ε-NbN is below ∼11.6 K, which is significantly higher than that for boron-doped diamond. The nature of superconductivity in hexagonal ε-NbN and the physical mechanism for the relatively lower T_C have been addressed by the weaker bonding in the Nb-N network, the co-planarity of Nb-N layer as well as its relatively weaker electron-phonon coupling, as compared with the cubic δ-NbN counterpart. Moreover, the newly discovered ε-NbN superconductor remains stable at pressures up to ∼20 GPa and is significantly harder than cubic δ-NbN; it is as hard as sapphire, ultra-incompressible and has a high shear rigidity of 201 GPa to rival hard/superhard material γ-B (∼227 GPa). This exploration opens a new class of highly desirable materials combining the outstanding mechanical/elastic properties with superconductivity, which may be particularly attractive for its technological and engineering applications in extreme environments.

Geochemical Transactions is ready to receive manuscripts on all aspects of geochemistry. The official journal of the Geochemistry Division of the American Chemical Society.

Hydrogeochemistry of 10 hot springs in the Kangding district was investigated by analyzing cation and anion concentrations in the spring water. The water samples were collected in the 5 days after the Lushan M_S = 7.0 earthquake, which occurred on 20 April 2013. The spring waters are classified into seven chemical types based on their hydrochemical compositions. Compared with hydrochemical data before the Lushan earthquake, concentrations of Ca²⁺, HCO₃^- and total dissolved solid (TDS) in water samples from the Guanding, Erdaoqiao, Gonghe, Erhaoying, Tianwanhe and Caoke springs significantly increased, which may be the result of a greater increase in groundwater from carbonate rocks, and water–carbonate rock interactions, enhanced by the increment of CO₂. Concentrations of Na⁺, Cl^- and SO₄^2- in water samples from the Guanding, Zheduotang, Xinxing and Gonghe springs decreased, indicating a dilution of shallow waters. Concentrations of Na⁺ and SO₄^2- in water samples from the Erhaoying spring water increased, which may be attributed to water–granite interactions enhanced by H₂S. The results indicated that hydrochemical components of spring water could be used as an effective indicator for earthquakes.

Hydrogeochemical changes in association with earthquakes are considered as a potential means of identifying earthquake precursors. The Xianshuihe fault zone (XSHF) is considered one of the most active seismic fault zones in China; 43 hot springs were sampled and analysed in the laboratory for major elements, silica, stable isotopes (δD and δ¹⁸O) and strontium isotopes were investigated from 2008 to 2021. The meteoric water acted as the primary water source of the hot spring in the XSHF, and recharged elevations ranged from 1.9 to 4.8 km. The geothermometers method was used to estimate the region of thermal storage temperature and its temperature between 8 and 142 °C. And the circulation depth ranged from 0.1 to 6.9 km. Most of the hot spring water was immature water with a weak degree of water-rock reaction. However, the degree of water-rock reaction and the depth of hot spring water circulation were high in part of the Kangding and Daufu segments, which also had the highest reservoir temperature and the most frequent strong earthquakes. Temporal variations of hydrogeochemical showed that Na⁺, Cl⁻ and SO₄²⁻ decreased obviously following the 12 May 2008 Wenchuan Ms8.0 and existed abnormal value fluctuations from the 20 April 2013 Lushan Ms7.0 to 22 November 2014 Kangding Ms6.3 occurred and after 20 July 2017 returned to the normal levels. And the ion concentrations in hot springs increased by 5% to 35% three months before 22 November 2014 Kangding Ms6.3 with the obvious precursor anomaly. Hydrogeochemical anomalies could be useful for predicting an earthquake in the study area.

地震的孕育和发生过程始终伴随着地下物质运移、能量传输和环境条件改变，并引发某些元素和同位素的迁移和演化. 因此，地球化学不但成为重要的地震异常研究方法，也是解释地震过程中物质和条件变化的重要手段. 此外，新的地球化学分析技术的迅速发展，使其在研究地震前兆机理和地震物理过程中发挥出越来越重要的作用. 在综述近年来流体地球化学在地震预测领域研究进展的基础上，结合自身团队的研究结果和认识，提出未来地震地球化学研究的优选发展方向.