The influence of land use change on karst water quality of Shuicheng Basin in Guizhou Province

The influence of land use and land cover on ecological environment is a focus of global change research. The paper chooses an industrial city-Shuicheng in Guizhou Province-as a study area because the karst water quality around the city is deteriorating with land use and land cover change. The natural susceptibility of karst water system is an important factor leading to karst water pollution. But land use and land cover change is also a main factor according to the chemical analysis of karst water quality and land use change. So it is a good way to protect karst water through rational planning and managing of land use and land cover.

A review of water resources utilization and protection in Southwest China

Yunnan and Guizhou are two provinces in Southwest China where in recent years drought disasters have occurred due to natural and human factors. This paper reviewed literature and summarized the related achievements of water resources utilization and protection in Yunnan and Guizhou provinces. rivers, and karst ground water in the two provinces, and also This included characters and utilization of precipitation, the various explanations of drought （climate and human factors） and strategies for coping with droughts. Our concluding remarks highlight three lines of future studies： inequalities and equitable use of water distribution, better evaluation systems, and raising awareness through conservation practices.

Movement characteristics of Karst water in a deep mining area

In order to study the movement characteristics of groundwater in a deep mining area and solve the dispute of the distri- bution rule of hydro-chemical zoning which is contradicted by lixiviation water zoning in a horizontal direction, we directed our attention to the source of deep groundwater, its seepage and hydro-chemical characteristics in a typical mining area. We used a neotectonic water-control theory, chemical and isotope methods, as well as a method for analyzing dynamic groundwater conditions. The results indicate that 1) Karst water in the deep and medium parts of this mining area is recharged by vertical leakage through neotectonic fractures rather than seepage along strata from subcrop parts or surrounding flows; 2) from surface to deep leakage paths, the variation in the types of chemical groundwater agrees with the normal lixiviation water distribution rule and the age of mixed groundwater increases; 3) the water-rich zones along neotectonic fractures correspond with water-diluted zones in a hori-zontal direction; 4) the leakage coefficient and water capacity of aquifers increases during the flow process of Karst water along the antidip direction (from west to east) and 5) Karst water in shallow mining areas forms a strong runoff belt along strikes and quickly dilutes the water from deep and medium mining areas. Overall, chemical and dynamic water characteristics actually agree with in terms of the entire consideration for differences in vertical leakage and abnormalities in the zone of water chemical distribution, along a horizontal runoff direction.

Study on the characteristics and causes of carbon tetrachloride pollution of karst water in eastern suburbs of Jinan

By comparing the testing data of the hydrochemistry components and organic pollution of karst water sample in Jinan with large amount of historical data, the author finds the long-existing problem of carbon tetrachloride pollution and the great change of hydrochemical characteristics of karst water in eastern suburbs of Jinan. Since karst water is the main water-supply source in eastern suburbs of Jinan, these problems have greatly affected the safety of water supply. Based on the analysis of hydrogeological condition in eastern suburbs of Jinan, this thesis discusses the causes of carbon tetrachloride pollution and hydrochemical variation with hydrogeochemical theories so as to protect the precious karst groundwater and Jinan spring water. It is found that through research and analysis that there are mainly two causes of carbon tetrachloride pollution and hydrochemical variation: the vulnerability of karst water in this area; the other being the serious pollution in this area caused by remaining pollution sources of the last century.

Isotope Hydrogeological Study of Karst Water in the Lu' an Mining District and the Xin'ancun Spring Basin, Shanxi

Isotope hydrogeological study has shown that the water supply exploration area in the Lu' an coal mine may be divided into four zones of hydrodynamic conditions and the Xin'ancun Spring Basin where the mine is located may be divided into three Middle Ordovician karst water systems. This paper discusses the features of recharge, runoff and discharge of karst water in various zones, and hydrogeological parameters such as the age, flow rate and natural recharge of karst water have been estimated.

Exploration of Water Resource and Multiple Model for Water Resource Development in Karst Areas with the Preferred Plane Theory

According to the theory of preferred plane, preferred planes (faults) alwayscontrol the distribution of bedrock fissure water and hold abundant groundwater. Thus, theexploration of fissure or karst water can be converted into searching for the watery preferred plane(WPP). In the paper, the characteristic of watery preferred planes is analyzed and a series ofsuperior indices has been set up. It is introduced that WPPs are determined by the methods ofgeological analysis, superior index and complex geophysical analysis. Meanwhile, new multiple modelfor water resource development in the water-scarce areas of karst mountainous regions are advanced.

Fluid–solid coupling analysis of rock pillar stability for concealed karst cave ahead of a roadway based on catastrophic theory

In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.

Effects of acid mine drainage on photochemical and biological degradation of dissolved organic matter in karst river water

Dissolved organic matter(DOM)can be removed or transformed by photochemical and biological processes,producing the negative effect of transforming organic carbon into inorganic carbon,which plays a vital role in the karst carbon cycle.However,acid mine drainage(AMD)will affect this process,so the degradation of DOM in karst river water(KRW)needs to be studied in this context.In this study,to reveal the evolution processes of DOM under photochemical and biological conditions in AMD-impacted KRW,AMD and KRW were mixed in different ratios under conditions of visible light irradiation(VL),biodegradation(BD),ultraviolet irradiation(UV)and ultraviolet irradiation+biodegradation(UV+BD).The average DOC concentrations in samples after mixing AMD and KRW in different proportions decreased significantly(by 23%)in UV+BD,which was 1.2–1.4 times higher than under the other conditions and would lead to a significant release of inorganic carbon.Further analysis of the fluorescence parameters via parallel factor analysis(PARAFAC)revealed that the DOM fluorescence components in AMD comprised mainly protein-like substances derived from autochthonous components,while the DOM fluorescence components in KRW were mainly humic-like substances with both autochthonous and allochthonous sources.Therefore,AMD could promote both the photochemical and biological degradation of DOM in karst receiving streams,resulting in the conversion of DOC to inorganic carbon.The results showed that the synergistic effects of UV+BD and AMD accelerated the degradation of DOM and the release of inorganic carbon in KRW,thus affecting the stability of the karst carbon cycle.

Response of Germination Physiology of Cajanus cajan Seeds to Drought Stress: Comparison between Karst Water and Allogenic Water Treatments

In this paper, responses of germination physiology of pigeon pea （Cajanus cajan） seeds to drought stress in karst water environment and non-karst （allogenic） water environment were studied to explore the adaptability of pigeon pea to karst environment. The results showed that： （i） Under drought stress of 20% PEG- 6000, the germination rate, vigor index, germination index and biomass of pigeon pea seeds on day 7 cultivated with karst water were all greater than that of the allogenic water treatment group, while the seed germination stress index was significantly smaller than that of the allogenic water treatment group, suggesting that karst water environment was more favorable to pigeon pea seed germination. （ii） Without drought stress, the malondialdehyde （MDA） and superoxide dismutase （SOD） activities of pigeon pea seeds cultivated with karst water were all smaller than that of the allogenic water group. However, under drought stress, the SOD activity was significantly higher than that of allogenic water group, suggesting pigeon pea SOD in karst water was able to more rapidly respond to external drought stress, and increase its own activity to reduce the damage to the plants. And （iii） with and without drought stress, the soluble protein level of the karst water group was higher than that of the allogenic water group, while the free amino acid level was lower than that of the allogenic water group. This difference was more significant with the presence of drought stress, suggesting that the karst water environment was more favorable to the accumulation of soluble proteins and thus produced larger biomass. Hence, pigeon pea is a tree species that is adapted to high-calcium, alkaline environments in karst areas, and is of great significance for the revegetation and rocky desertification control in mountainous karst areas.

Hydrogeochemical and Isotopic Evidence for Flow Paths of Karst Waters Collected in the Heshang Cave,Central China

Understanding of hydrological processes in caves is important to help us interpret paleoclimate records from speleothems. In this study, we integrated hydrogeological and hydrogeochemical properties to characterize the hydraulic behavior of karst waters in the Heshang Cave, Central China. Using geological and topographical analyses, we identified regional watershed boundaries and hydrogeological connections that were controlled by anticlinal geometry and faults. Water samples were collected from the Heshang Cave and potential recharge sites. Geochemical data of c（Sr^2＋）/c（Ca^2＋） and c（Mg^2＋）/c（Ca^2＋） ratios suggest that the drainage system in Heshang Cave consists of two flow paths. For vadose waters, including drip water and rimstone pool water, c（Sr^2＋）/c（Ca^2＋） ratio ranges from 0.000 6 to 0.001 1, and c（Mg^2＋）/c（Ca^2＋） ratio ranges from 0.97 to 1.1, indicating that recharge was mainly from rainfall infiltration through the overlying Cambrian dolomite stratum. In contrast, slope current and underground river waters have higher c（Sr^2＋）/c（Ca^2＋） ratios （values from 0.002 2 to 0.002 8）, and lower c（Mg2＋）/c（Ca^2＋） ratios （values from 0.50 to 0.64）. These waters show homogeneous isotopic composition （δ^18O： -7.15‰- -6.95‰; δD： -52.73‰- -51.31‰）, implying recharge of allogeneic water from the Xiaocr River via karst conduits that pass through Ordovician limestone and Cambrian dolomite stratum.