Hydrogeological Functioning of a Karst Underground River Basin in Southwest China.

The Maocun underground karst river system in the peak cluster depression is an important source of groundwater in southwest China. Multitracers and high resolution water-level-monitoring technology were used to assess and evaluate the hydrogeological structure and flow dynamics. The results showed that the spatial geological structures of the sites had high heterogeneity.

[Evaluation of Heavy Metal Content, Sources, and Potential Ecological Risks in Soils of Southern Hilly Areas].

In order to explore the characteristics of soil heavy metal pollution and ecological risk status in southern hilly areas, a hilly area of a southern province was selected as the research area, using soil samples collected at 60 points in 2017. The single factor pollution index (), Nemero comprehensive pollution index, and potential ecological risk index (RI) were used to evaluate the content characteristics and potential ecological risks of eight heavy metal elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn), and positive definite matrix factor analysis models (PMF) were used to analyze their sources of pollution. The results were as follows:① the content of eight heavy metal elements in the study area exceeded the standard, and the Nemeiro comprehensive pollution index showed that the proportions of light, moderate, and heavy pollution in the study area were 63%, 8%, and 2%, respectively.

[Water Chemical Characteristics and Influence of Exogenous Acids in the Yangtze River Basin].

To explore the influence of human activities on the Yangtze River water chemistry, water samples were obtained from a representative section the main river stem/branch in wet and normal seasons in 2016. Ion ratio analysis, principal component analysis(PCA), and chemical ion balance calculations were performed, and carbonate rock dissolution rates were determined based on carbonate and exogenous acids. The result show that HCO-Ca is the dominant hydrochemistry type, indicating that the dissolution of carbonate rocks in the basin is the main process affecting hydrochemistry, and carbonate acid is significant in the weathering of carbonate rocks.

Dynamics in riverine inorganic and organic carbon based on carbonate weathering coupled with aquatic photosynthesis in a karst catchment, Southwest China.

Carbonate mineral weathering coupled with aquatic photosynthesis, herein termed 'coupled carbonate weathering' (CCW), represents a significant carbon sink which is determined by riverine hydrochemical variations. The magnitudes, variations and mechanisms responsible for the carbon sink produced by CCW are still unclear. In this study, major ions, TOC and discharge data at the Darongjiang, Lingqu, Guilin and Yangshuo hydrologic stations in Li River basin, a karst catchment typical of this geographic region, were analysed from January 2012 to December 2015 to elucidate the temporal variations in riverine inorganic and organic carbon and their controlling mechanisms.

[Dynamic Changes in Hydrochemical Characteristics and Influencing Factors in the Karst Watershed Flood Process].

The hydrochemistry of river water in a karst basin has a rapid response to the rainstorm/flood process, which is an important process of the karst carbon cycle and should not be ignored. Based on the dynamic monitoring of the hydrochemical characteristics of the flood process in the Yangshuo section on November 8-12, 2015, the dynamic change in the main ions and the influencing factors were analyzed, and the concentration and flux of inorganic carbon from different sources were calculated. The results showed that the hydrochemistry types in different stages of the flood area belonged to the Ca-HCO type.

Effects of aquatic phototrophs on seasonal hydrochemical, inorganic, and organic carbon variations in a typical karst basin, Southwest China.

Karst processes play an important role in the global carbon cycle. Aquatic phototrophs can transform bicarbonate, which is mainly derived from the weathering of carbonates, into organic carbon. Carbonate mineral weathering coupled with aquatic photosynthesis can be considered a stable and durable carbon sink process.

[Fate and Origin of Major Ions in River Water in the Lhasa River Basin, Tibet].

In order to understand the temporal and spatial variations of major ions in water and their sources in the Lhasa River Basin, water samples were collected monthly at the hydrological station in the Lhasa River from August 2014 to July. The results show that HCO is the dominant anion in the water of the Lhasa River, which accounts for 68.73% of the anions, followed by SO.

[Spatial Variation and Environmental Significance of δO and δD Isotope Composition in Xijiang River].

The H and O isotope composition of the Xijiang water was investigated on 54 samples collected from the mainstreams and main tributaries in June 2014 and January 2015.It was found that in the Xijiang river, there was a remarkable linear relationship between δ O and δD. This relationship was more significant in the dry season.

[Chemical Characteristics and Source of Acid Precipitation in Guilin].

A total of 396 rainwater samples of Guilin from 2008 to 2011 were collected and analyzed for pH, 44 of which were analyzed for major ions. The analysis of pH values showed the obvious seasonal variation of acid rain in Guilin. The pollution level of summer was lower than those in other seasons, while the pollution levels in winter and spring were the highest.

[Endovascular treatment of ruptured aneurysms located at anterior communicating artery complex: a sixty-six cases report].

Objective: To investigate the endovascular treatments for the ruptured aneurysms located at anterior communicating artery complex (ACoAC).

Methods: The data of patients with ruptured ACoAC aneurysms treated in Department of Neurosurgery, First Affiliated Hospital to Fourth Military Medical University from May 2013 to December 2014 was retrospectively analyzed. Sixty-six cases were recruited including 50 male and 16 female patients.

[Hydrochemical Characteristics and Influencing Factors in Different Geological Background: A Case Study in Darongjiang and Lingqu Basin, Guangxi, China].

The observation and sampling were carried out in May 2013 to April 2014 in a hydrological year for two river basins with different geological background in upstream of Li river basin. The seasonal variations of river water chemistry and its main influencing factors were discussed in this paper. The results showed that the hydrochemistry types of both Darongjiang basin with 9% of carbonates and Lingqu basin with nearly 50% of carbonates in area belonged to Ca-HCO3 type.

[Summer Greenhouse Gases Exchange Flux Across Water-air Interface in Three Water Reservoirs Located in Different Geologic Setting in Guangxi, China].

Due to special hydrogeochemical characteristics of calcium-rich, alkaline and DIC-rich ( dissolved inorganic carbon) environment controlled by the weathering products from carbonate rock, the exchange characteristics, processes and controlling factors of greenhouse gas (CO2 and CH4) across water-air interface in karst water reservoir show obvious differences from those of non-karst water reservoir. Three water reservoirs (Dalongdong reservoir-karst reservoir, Wulixia reservoir--semi karst reservoir, Si'anjiang reservoir-non-karst reservoir) located in different geologic setting in Guangxi Zhuang Autonomous Region, China were chosen to reveal characteristics and controlling factors of greenhouse gas exchange flux across water-air interface. Two common approaches, floating chamber (FC) and thin boundary layer models (TBL), were employed to research and contrast greenhouse gas exchange flux across water-air interface from three reservoirs.

[Variations of Inorganic Carbon and its Impact Factors in Surface-Layer Waters in a Groundwater-Fed Reservoir in Karst Area, SW China].

In order to understand the inorganic carbon cycle of the groundwater-fed reservoir in karst area, Dalongdong Reservoir, which is located at Shanglin County, Guangxi Zhuang Autonomous Region, China, was investigated from 12th to 20th July, 2014. Concentration of dissolved inorganic carbon (DIC), delta13C of DIC (delta13C(DIC)), partial CO2 pressure (pCO2) and CO2 flux across water-air interface were studied by observation in situ and high-resolution diel monitoring. Results show that: (1) DIC concentration and water pCO2 increased from upstream area to downstream area [DIC(average)): from 122.

[Effect of hydrochemistry characteristics under impact of human activity: a case study in the upper reaches of the Xijiang River basin].

In this paper, observation and sampling were taken three times a month in a hydrological year for three typical sections of the middle and upper reaches of the Xijiang River basin, based on the data of hydrochemistry and flow, the article mainly discusses the evolution process of hydrochemistry in river under natural process and impact of human activity. Hydrochemical characteristics of 116. samples were analyzed in the study area.