[Hydrochemical Characteristics and Its Origin of Surface Water and Groundwater in Dianbu River Basin]

Chaohu lake is a key water body for water pollution prevention and treatment in our country. However， it has been at a higher eutrophication level recently. Here， the surface water and groundwater in the Dianbu River Basin， a secondary tributary of Chaohu Lake， were taken as the research object. In order to test the hydrochemical composition and hydrogen and oxygen isotope values of different water bodies， 30 groups of surface water samples， 36 groups of groundwater samples， 16 groups of hydrogen and oxygen stable isotope samples， and 18 groups of groundwater hydrogen and oxygen stable isotope samples were collected in August 2021 （wet season）， November 2021 （normal season）， and February 2022 （dry season）. The seasonal and spatial variation characteristics were analyzed to explore the hydrochemical characteristics and formation mechanism of water bodies by means of mathematical statistics， Piper triangular diagram， Gibbs figures， and ion ratios. The following results were obtained： ① precipitation was the main source of surface water and groundwater in Dianbu River Basin， and the evaporation fractionation effect of surface water was more significant than that of groundwater. At different periods， the surface water was more enriched with stable isotopes of hydrogen and oxygen than groundwater. The stable isotopes of hydrogen and oxygen in water showed seasonal variation， relative enrichment in the wet season， and depletion in the dry season. ② Both surface water and groundwater in the Dianbu River Basin were weakly alkaline， and the concentration of ions in surface water was significantly lower than that in groundwater. Ca2+ and Na+ were the main cations in surface water， Ca2+ was the main cation in groundwater， and the dominant anion in all water was HCO3-. The hydrochemical typology of surface water was mainly HCO3·Cl-Na·Ca， and that of groundwater was mainly HCO3-Na·Ca. ③ The concentrations of the main hydrochemical indexes of surface water and groundwater showed certain seasonal and spatial differences. From the wet season to the dry season， the concentrations of TDS， K+， Na+， Ca2+， Mg2+， Cl-， and SO42- in surface water showed an increasing trend on the whole. The concentrations of Na+， Ca2+， and Mg2+ in groundwater showed little change but increased slightly， whereas the concentrations of Cl-， SO42-， and NO3- showed an increasing trend on the whole. The concentrations of Cl-， SO42-， and NO3- in the water showed relatively large seasonal fluctuations. From upstream to downstream， the concentrations of the main hydrochemical indexes in surface water first decreased and then increased， among which the concentration of NO3- increased the most. The concentrations of the main hydrochemical indexes of groundwater in the direction of runoff changed little overall， but the concentration in the discharge area was higher than that in the recharge area. ④ The formation of hydrochemical characteristics of the water was mainly controlled by water-rock interaction but was also influenced by human factors. The water-rock action was mainly the weathering dissolution of silicate rock， salt rock， and carbonate rock. Man-made pollutants such as sewage from a sewage treatment plant， domestic sewage， and feces had obviously changed the hydrochemical characteristics of the local water. ⑤ Compared with that in 2016， the concentration of NO3- in surface water showed a certain degree of reduction. The nitrogen pollution control work carried out by the local government had achieved certain results， but it was still necessary to strengthen the pollution prevention and control of sewage and feces in the downstream of the Dianbu River， some tributaries （such as the Dingguang River and Maqiao River）， and some residential areas.

[Hydrochemical and Isotopic Characteristics in the Surface Water of the Fenhe River Basin and Influence Factors]

The Fenhe River Basin is the mother river of Shanxi Province. Due to the over-exploitation of water resources and the impact of social and economic development, the ecological environment has deteriorated. After a series of treatment and protection measures, the water quality has since been improved. Mathematical statistics, Piper diagrams, Gibbs model, hydrogen and oxygen isotopes, and other methods were used to analyze the characteristics and sources of hydrochemistry in the surface water of the Fenhe River basin, which revealed the evolution process of surface water quality of the Fenhe River basin. The results showed that the content of the main hydrochemical components in the main stream surface water of Fenhe River basin increased gradually along the runoff path. The hydrochemical types of surface water of Fenhe River basin were mainly HCO₃·SO₄·Cl-Ca·Na·Mg and SO₄·HCO₃·Cl-Ca·Na·Mg. There were great differences in hydrochemical components of tributaries and karst water in the basin. There were also great differences in hydrochemical components of tributaries in the basin. The hydrochemical types of surface water of karst water were mainly SO₄·HCO₃-Ca·Mg. The hydrochemical composition of surface water in Fenhe River basin was mainly affected by rock weathering and evaporation crystallization, whereas rainfall had little effect. Na⁺ and K⁺ mainly came from the dissolution of evaporated salt rocks with Na in the surrounding loess. Ca²⁺, Mg²⁺, and HCO₃^- mainly came from the dissolution of carbonate rocks. SO₄^2- may have also come from the dissolution of sulfide minerals in the loess layer around Fenhe River in addition to the dissolution of gypsum. The values of δD and δ¹⁸O of Fenhe River surface water were gradually enriched from upstream to downstream. The characteristics of hydrogen and oxygen isotopes further showed that the surface water was mainly affected by evaporation. The results of this study can provide evidence for ecological restoration and protection and ecological civilization construction in the Fenhe River basin.

Recent Advances of In-Source Electrochemical Mass Spectrometry

Hyphenation of electrochemistry (EC) and mass spectrometry has become a powerful tool to study redox processes. Approaches that can achieve this hyphenation include integrating chromatography/electrophoresis between electroinduced redox reactions and detection of products, coupling an EC flow cell to a mass spectrometer, and performing electrochemical reactions inside the ion source of a mass spectrometer. The first two approaches have been well reviewed elsewhere. This Minireview highlights the inherent electrochemical properties of many mass spectrometry ion sources and their roles in the coupling of electrochemistry and mass spectrometric analysis. Development of modified ion sources that allow the compatibility of electrochemistry with ionization processes is also surveyed. Applications of different in-source electrochemical devices are provided including intermediate capturing, bioanalytical studies, nanoparticle formation, electrosynthesis, and electrode imaging.

[Hydrochemical Characteristics and Analysis of the Qilihai Wetland, Tianjin]

Hydrochemistry is an important parameter for wetland water environmental assessment. To study the hydrochemistry and main ion sources in the Qilihai wetland in Tianjin, river water, groundwater, and water in the marsh were collected and analyzed. The results show that:① The river and marsh waters are SO₄·Cl-Na in type and groundwater water is HCO₃-Na and HCO₃-Na·Ca in type. The water in the marshes is mainly recharged by river water and the exchange of shallow groundwater with river water is notable; ② Precipitation has little effect on the chemical composition of the water. Na⁺ and K⁺ were derived from the dissolution of salt rock and evaporative concentration. Ca²⁺, Mg²⁺, and HCO₃^- in the river and marsh water are mainly derived from the dissolution of evaporite salt rock. Ca²⁺, Mg²⁺, and HCO₃^- in the groundwater are mainly derived from carbonate mineral dissolution; ③ The hydrochemical composition of the river water and groundwater is notably affected by ion exchange, but this was not observed in the marsh water. Furthermore, SO₄^2- and NO₃^- are affected by human activity. During the dry season, the river and marsh water are affected by evaporite salt rock dissolution, evaporation, and human effects, while in wet season, river water is mainly affected by carbonate dissolution and human activities. These observations demonstrate how that hydrochemical composition of this wetland is controlled by a combination of natural factors and human activities.

[Hydrochemical Characteristics and Evolution of Groundwater in the Kashgar Delta Area in Xinjiang]

Pollution-induced water shortage problems have severely hindered the economic development of Kashi Prefecture in Xinjiang. In order to study the chemical characteristics and main ion sources of groundwater in the Kashgar River Delta of Western Kashi Prefecture, 402 groundwater samples and 114 groundwater hydrogen and oxygen isotope samples were collected and tested in June to October 2016. Based on the methods of mathematical statistics, Gibbs diagram, ion ratio, Schoeller diagram, and hydrogeochemical simulation, the hydrogeochemical characteristics of the groundwater were analyzed, and the hydrochemical evolution law and the main ion sources were discussed. The following results were noted. ①SO₄^2- was the main anion in the groundwater, followed by Cl^-. Na⁺ was the main cation, and the groundwater was mainly SO₄·Cl-Na type. ②The groundwater ion components were controlled by dissolution of rocks and evaporation. The groundwater ions were mainly derived from the dissolution of evaporites, followed by the dissolution of carbonates. Unconfined groundwater in the river alluvium plain was affected by evaporation, and the confined groundwater was affected by reverse cation exchange and mixing. ③Along the groundwater flow direction, the concentration of ion components in the groundwater increased. Halite, dolomite, and gypsum were dissolved, and calcite was precipitated.

[Major Ionic Features and Their Possible Controls in the Surface Water and Groundwater of the Jinghe River]

To study the hydrochemical characteristics of tributaries of the Jinghe River (Heihe River Basin) and their controlling factors, from 2014 to 2015, 242 samples of surface water and groundwater were collected during the dry and flood seasons from the Jinghe River. After determining the main water chemical ion content by comprehensively using correlation analysis, Piper three-line graphs, and Gibbs graph, the spatiotemporal changes in the hydrochemical characteristics of the Heihe River Basin were analyzed. The results showed that all the water samples in the study area were weakly alkaline. In the dry season of 2014, the cations in the surface water and groundwater were mostly Na⁺, accounting for 56% and 58% of the total cations, respectively. The anions were mainly SO₄^2-, accounting for 33% and 39% of the total anions, respectively. In the other three periods, the main cation and anion components were HCO₃^- and Na⁺, accounting for 44%-46% and 42%-56% of the corresponding totals, respectively. In the dry season, the TDS of surface water and groundwater gradually increases along the river from upstream to downstream. From the dry season to the flood season, the hydrochemical types of the surface water changed from Na-Mg-Cl-SO₄ to Ca-Mg-HCO₃ and of the groundwater from Mg-Cl-SO₄ to Ca-Na-HCO₃. Most of the water chemistry samples were distributed in the middle and upper parts of the Gibbs diagram, indicating that the formation of hydrated chemical ions in the basin was mainly affected by rock weathering and evaporation-enrichment. However, the effects of human activities on water chemistry were more significant in the dry season than in the flood season.

Installation of hybrid ion source on the 1-MV LLNL BioAMS spectrometer

A second ion source was recently installed onto the LLNL 1-MV AMS spectrometer, which is dedicated to the quantification of 14C and 3H within biochemical samples. This source is unique among the other LLNL cesium sputter ion sources in that it can ionize both gaseous and solid samples. Also, the injection beam line has been designed to directly measure 14C/12C isotope ratios without the need for electrostatic bouncing. Preliminary tests show that this source can ionize transient CO2 gas pulses containing less than 1 ug carbon with approximately 1.5% efficiency. We demonstrate that the measured 14C/12C isotope ratio is largely unaffected by small drifts in the argon stripper gas density. We also determine that a tandem accelerating voltage of 670 kV enables the highest 14C transmission through the system. Finally, we describe a series of performance tests using solid graphite targets spanning nearly 3 orders in magnitude dynamic range and compare the results to our other ion source.