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2014 Vol. 33, No. 2

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Utilization of karst water HCO3-, Ca2+ by Chlorella vulgaris under different Cd2+ concentrations stress
HU Qing-jing, WANG Pei, HUA Lei, CAO Jian-hua, LI Qiang
2014, 33(2): 123-128.
Abstract PDF(1816KB) icon1906 icon1523
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The carbon sink effect of algae is a hot topic in global carbon sink research. At the end of 2012, the Longjiang river cadmium pollution event greatly harmed downstream aquatic life. In order to study the effect of cadmium pollution on the algae carbon sink effect, this experiment explored the HCO3- and Ca2+ in karst water used by Chlorella vulgaris cultivated in a closed system under the stress of different Cd2+ concentrations (0, 10, 20, 40 μmol/L), as well as changes to pH and the biomass of Chlorella vulgaris in the system. The results indicated that HCO3- and Ca2+ utilization by Chlorella vulgaris photosynthesis is essentially unchanged when the Cd2+ concentration is in the range of 0 μmol/L to 10 μmol/L. When the Cd2+ concentration is 10-40 μmol/L, the use of HCO3- and Ca2+ in karst water by Chlorella vulgaris is inhibited. When the Cd2+ concentration exceeds 40 μmol/L, Chlorella vulgaris essentially doesn’tuse the HCO3- and Ca2+ in the closed system. Furthermore, pH drift experiments show that when the Cd2+ concentration is in the 0 μmol/L to 20 μmol/L range, Chlorella vulgaris can simultaneously use the free CO2 and HCO3- in karst water for photosynthesis. But when the Cd2+ concentration is between 20 μmol/L and 40 μmol/L, Chlorella vulgaris only uses free CO2 as the carbon source. Therefore, the cadmium pollution in karst aquatic ecosystem has a pronounced impact on the algae carbon sink. 
Paleoenvironmental changes inferred from diatom and geochemistry records of lake deposits: A case study in Huixian karst wetland, Guilin
WANG Liang-chi, ZHANG Qiang, XIAO Liang-jian, HU Zhi-an, LI Hong-chun, XIE Yun-qiu
2014, 33(2): 129-136.
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The Holocene paleolimnological variations in Huixian karst wetland, Guilin, and the climate changes as well as human activities that they reflect, have been reconstructed using multiproxies, including radioactive dating, geochemical proxy, and diatom analysis of a sediment core from Shizitan Lake. During 6 400-5 200 cal BP, high percentages of planktonic diatoms indicated higher water levels, corresponding to a warm and humid climate during the Holocene Optimum. During 5 200-2 700 cal BP, the decline of weak acid leachable Ca, Mg, Sr, and the increase of Mg/Ca, Sr/Ca ratios, associated with low percentages of planktonic diatoms inferred a marked decline in water levels and drier climate. The re-accumulation of lake sediments in A.D. 1943 may correlate to significant population shifts during World War 2. The numerous deposits of diatom valves since A.D. 1973, showed algal blooms as a consequence of intense human impacts.
Recognition on recharge of Shaizhudong spring in the central Weibei, Shaanxi Province, China
MA Zhi-yuan, YUN Zhi-han, LI Xiu-cheng, ZOU Jian-feng, HOU Chen, WAN Wei-feng
2014, 33(2): 136-145.
Abstract PDF(4881KB) icon2004 icon1416
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Shaizhudong spring is located between middle-low mountains and Weibei loess tablelands. The overall terrain trend of the study area is that it is higher in the northwest than in the southeast.The north area is mainly middle-low mountains with elevations of about 1 200 to 1 600 m, and it mainly consists of exposed or concealed carbonate rocks. In the southwest the terrain gradually decreases, with altitudes of 800 to 1 000 m, and a series of Tangwangling synclinal fold structures consisting of Ordovician clastic and carbonate rocks. The terrain of the southeast area shows a ladder-like decrease and the elevation of the piedmont zone is between 400 and 500 m, which is located between exposed carbonate area and piedmont alluvial-pluvial fan sector. Shaizhudong spring is the largest karst spring in central Weibei, Shaanxi Province, China. Its supply source has been the topic of a lot of research, and it was thought that Jinghe leakage was the main recharge source, and it was the main discharge point in the hiden karst system of shaizhudong spring area. In this paper, we have a different understanding of the recharge of Shaizhudong spring, based on research into hydrogen, oxygen and strontium isotopes, combined with hydro-geochemistry and karst hydrogeological conditions. Isotope hydro-geochemistry study showed that the recharge was given priority to karst groundwater outside southwest of the Shaizhudong spring area. The proportions of atmospheric precipitation, river water and karst water were 11 %, 37 % and 52 % of all the supply source, and proportion in the southwest, northwest and the dam site area karst water were 77.9 %, 19.7 % and 2.4 % in the karst water supplies, respectively. On this basis, this paper also estimates that the average residence time of Shaizhudong spring karst water is 62-64 years based on tritium isotope data.
Environmental signification and characteristics of δD and δ18O variation in drip water in Yangkou cave, Chongqing
WANG Hai-bo, LI Ting-yong, YUAN Na, LI Jun-yun
2014, 33(2): 146-155.
Abstract PDF(4034KB) icon2163 icon1263
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To explore the variation of water δD, δ18O and its environmental significance, drip water and local meteoric precipitation were collected monthly from Yangkou cave in Jinfo Mountain, Nanchuan district, Chongqing, China, from October 2011 to August 2013, which were used for the analyze of the hydrogen and oxygen stable isotopes. By comparing the distribution and seasonal changes of δD and δ18O values, and the correlations with rainfall and temperature, some summaries can be concluded as below. (1) For all the six monitoring sites, the δD and δ18O data of drip water distributed closely to the Local Meteoric Water Line (LMWL), δD=8.75δ18O+22.14, which was built up based on the δD and δ18O data of local precipitation. This means that there was no significant evaporation for the precipitation during the infiltration into the cave, and the δD and δ18O of drip water represent the average composition of local precipitation. (2) The amplitudes of δD and δ18O variation for drip water were -46.77 ‰～ -62.09 ‰ and -7.05 ‰～ -9.96 ‰ respectively, obviously less than the amplitudes of δD and δ18O for local precipitation, which were 5.17 ‰～ -115.63 ‰ and -1.44 ‰～ -16.10 ‰ respectively. In additionally, the δD and δ18O variations of drip water lagged to those of local precipitation. This should be attributed to the adjustment capacity of the overlying soil and bedrock. While, because of the seasonal change of moisture source, for both of the local precipitation and drip water, the δD and δ18O variation charactered as lighter in summer months and heavy in winter months. The relatively extensive δD and δ18O variation of drip water among different drip sites, maybe should be attributed to the difference of fissures in the bedrock, thickness of overlying stratum, residence time of underground water, migration length, dripping height and rate, and the distance between the drip site and entrance, and so on. (3) The δ18O of precipitation presented amount effect to rainfall and negative correlation with temperature. In general, the δ18O of drip water negatively correlated to rainfall too, but the correlation between drip water δ18O and temperature (water temperature and air temperature in cave) was diversified. E.g. there was no correlation for sites 1#、2#、5#、6#, positive correlation for site 3# and negative correlation for site 4#. It seems that these various correlations between drip water δ18O and temperature should partly be attributed to the different seasonal change of drip water δ18O among the drip sites. (4) In a word, mixing effect in the bedrock overlying the cave hiding the seasonal change of δD and δ18O in precipitation, resulted in smooth seasonal change of δD and δ18O in drip water. So, it may be at a low possibility to reconstruct paleoclimate change at seasonal resolution based on the stalagmite in Yangkou cave. While, the δD and δ18O of drip water inherited the change of local precipitation, the stalagmite δ18O in this cave can record the paleoclimate change at long time scale as annual-decades or even longer.
The covered karst water resource evaluation and mining plan prediction in Daxing overlapping uplift area
NAN Tian, LI Peng, LI Xing-yu, WANG Xin-juan, XIE Zhen-hua, SHAO Jing-li
2014, 33(2): 156-166.
Abstract PDF(8856KB) icon2196 icon1368
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The Daxing overlapping uplift area is located in the middle and lower reaches of the alluvial-proluvial plain of the Yongding and Chaobai rivers in the south of Beijing. The karst water under the quaternary aquifer has good quality and large storage. With the development of the urban area, the demand for groundwater has increased. Leadings to increased use of the karst water. With the continuous decline of the karst water level, it is essential to assess the groundwater resource and analyze the exploitation plan. A numerical model was set up by means of GMS, simulating the karst groundwater flow system and predicting variations in the groundwater level. The model was conceptualized with five layers, the 1st and 2nd layers are quaternary aquifers, the 3rd to 5th layers are karst aquifers. The model was calibrated using historical data spanning 12 years and 9 months. According to the model’s water budget, the recharge of the groundwater system is 14,425.74×104 m3/a, the total allowable exploitation of the groundwater system is 14,310.52×104 m3/a, of which the karst aquifer is 2,309.36×104 m3/a. Analysis of the groundwater budget indicates, that the main recharge of the karst water aquifer is the leakage from the upper quaternary aquifer. Considering the local hydrogeological condition and the groundwater supply conditions, four exploitation plans have been proposed,(1)Maintain current exploitation;(2)Exploit according to the allowable exploitation level;(3)Maintain current exploitation until 2020, exploit by according to allowable exploitation level after 2020;(4)Maintain current exploitation until 2020, then stop the Niantan water source exploitation after 2020, and exploit according to the allowable exploitation level after 2025. By analyzing the stage hydrograph of typical observed well and the water balance, The 4th plan is the best exploitation plan.In conclusion, the model is fit to describe the local hydrogeological features and has been successfully applied to predict changes in groundwater level.
Renewable assessment for geothermal resources in the karst area of Chongqing City
YANG Hua-lin, LI Ming-lun, ZHOU Shen-bo, YANG Sen
2014, 33(2): 167-175.
Abstract PDF(4817KB) icon1821 icon1498
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The geothermal resources of the main city of Chongqing karst area are mainly located in the layered heat storage structure of five anticlines. The geothermal fields are mainly in the limbs and south or north plunging ends of the anticlines. The Triassic Jialingjiang limestone is a heat reservoir, with overlying Xujiahe Formation and Jurassic strata, and with the marl of the Triassic Feixianguan Formation serving as the lower heat insulation layer. With increasing geothermal economic development and engineering construction, Chongqing City geothermal water resources renewability has been affected. In this paper, based on years of geothermal resource exploration and monitoring in Chongqing City, the five anticline reservoir structures in the karst area were divided into spring outcrops and deeply buried anticline, zones and the renewability of the geothermal resources was evaluated using the comprehensive index method. The results show that, the geothermal resources in the karst area can be classified as: 5 strong renewable, 10 moderately-strong, 8 moderate and 7 weak, comprising 12.95 %, 32.2 %, 32.15 % and 22.7 % by area, respectively, and shows a moderately-strong to moderate renewability overall. Moderately-strong and moderate renewable spring-type geothermal resources account for 33.6 % and 33.95 %, respectively, by area. Strong and moderately-strong renewable deeply buried resources account for 25.9 % and 30.8 % by area. Strong to moderately-strong renewable geothermal resources are mainly located in the northern anticline, moderate to weak renewable geothermal resources are found in the middle and southern anticlines. In general, deeply buried geothermal resources are more strongly renewable than spring-type resources. Therefore, this article suggests strengthening the exploration and development of geothermal water resources in the deeply buried area of the northern anticline limbs. At the same time, in order to ensure the sustainable utilization of geothermal resources, the scale of mining should be controlled in the moderate to weak renewable geothermal resources areas, the deeply buried anticline limbs areas in the south and the part - Hot Springs outcrop areas.
Analysis of hydrological process of drip water in the aeration zone of a typical karst stone hill
GUO Xiao-jiao, JIANG Guang-hui, Tang Qing-jia, Huang Si-yu, Liu Shao-hua
2014, 33(2): 176-183.
Abstract PDF(4557KB) icon1812 icon1398
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Xiaoyan cave is located in Yaji village approximately 8 km southeast of Guilin City in Guangxi (N25°14′53, E110°22′33). Geomorphologically, the cave is on the boundary between adjacent peak cluster and peak forest karst systems. Xiaoyan cave is developed in massive pure Upper Devonian limestone with a bioclastic sparite to micrite texture. The limestones dip gently toward the south-west. The altitude of the cave is 197.5 m. The total length of cave measures 100 m, the width of cave is about 25 m and the thickness of the cave roof is approximately 20-150 m. XY5 is a perennial drip point, which is the largest drip water point in the cave. The overburden above the cave is about 0.3-1 m thick. The area has a subtropical monsoon climate with mean temperature of 18.9℃， and long-term mean annual rainfall of 1 886 mm.In order to study the hydrological processes of cave drip water flow, cave drip water was sampled, and water level, conductivity, and temperature were automatically monitored in Xiaoyan cave’s karst aeration zone. The response of the drip water, water chemistry and dynamic characteristics to the rain was analyzed. The results indicate that the drip water flow rate, conductivity and water temperature have a good corresponding relationship. Rainfall, rainfall intensity and the pre-rainfall water content of the rock and soil mass overlying Xiaoyan cave are the main factors affecting water flux; the flow rate ranges from 23.15 to 589.47 mL/s. Temperature has the fastest response to rainfall, while water flux and conductivity basically increase at the same time. Water temperature is mainly affected by the local temperature. Conductivity exhibits obvious seasonal changes,with higher values and lower amplitude in the rainy season, lower values and and a large amplitude in the dry season. Due to the hydrological processes of the wet and dry conditions, combined with dynamic changes in the main hydrochemical components in the dry season, conductivity and temperature exhibit three peaks. The different peaks correspond to different runoff water: preferential flow, soil-rock interface runoff and fracture water. Therefore, through the hydrological processes and the dynamic change characteristics of hydrochemical indicators, we can qualitatively reflect the drip water source, flow paths, time and the changes in environment conditions.
Research about the control of geological structure on karst groundwater system in Zhangfang, Beijing
QIAO Xiao-juan, HOU Quan-lin, JU Yi-wen, LIU Kai, ZHANG Yu-xiu, GUO Gao-xuan
2014, 33(2): 184-191.
Abstract PDF(6468KB) icon1510 icon1292
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Carbonate formations are intensively distributed throughout Zhangfang, Fangshan, in the West Mountain area of Beijing. Karst groundwater exits among the geological fracture network which is characterized by the different arrangements and levels in different types of fracture networks and structures. The influence of the tectonic environment on the dynamic change rule and the enrichment regulation of karst groundwater system is significant for the exploitation and protection of karst groundwater resources.From the control function of fault and fracture point of view, based on the developmental and distribution pattern of multi-episodic tectonism, this study analyzed fractures in the three-fold structural units characterized by NE-NW and NS trends and discussed the influence of multi-episodic tectonism on groundwater flow, the spring system and rich water zones.The results showed that the geological fracture underwent two episodes of tectonism, thrusting nappe in the Jurassic and extension in the Cretaceous. The overprint of the processes of the two tectonic episodes resulted in a number of faults with high hydraulic conductivity, which serve as conduits. The superior joint groups are in the NE and NW directions, with conjugated characteristics. The high-angle or vertical dips directly benefit infiltration. The fractures in the intersection areas have formed groundwater runoff channels and storage space, controlling water-rich zones such as Baidai, Ganchi-Changgou and Gaozhuang-Shiwo. Magmatic rock and the aquiclude also contribute to the rich water zones and the location of springs, all of which have important significance for water supply.
Ecological characteristic of Bryophyte communities from karst peak cluster rock desertification in Guanling county, Guizhou
ZHANG Tian-han, DAI Yu, WANG Zhi-hui, ZHANG Zhao-hui
2014, 33(2): 192-200.
Abstract PDF(1422KB) icon1926 icon1378
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Guanling county is in the ramp strip on the south side of ridged ramp from the east of Yunnan-Guizhou Plateau to hills of Guangxi,the carbonate was widely distributed and it is the typical mountains of karst.Strong soil erosion makes vegetation degradation and rocky desertification stronger in the place.Bryophyte belongs poikilohydric plants,it has good physiological drought tolerance and adapt environment of arid.For finding out the species and characteristics of bryophyte communities in the place of karst rocky desertification peak cluster, three typical areas(bare rock,natural vegetation,artificial vegetation) of karst peak cluster rock desertification was surveyed,we study the composition,distribution and ecological characteristics of the bryophyte communities in the area,PIE(Interspecific Encounter Probability),ecological dominance,Shaanon-Wiener niche breadth formula and Morisita-Horn niche overlapping formula were used.The results are as follows:(1)The bryoflora of this site includes 11 families,17 genera and 22 species,Bryaceae is the dominant families,19 types of bryophyte communities were concluded in the area.(2)The PIE of bryophyte communities is direct ratio to vegetation coverage and inversely proportional to bare rock ratio,the PIE of mixed forest in karst peak cluster rock desertification is higher than the other two habitats,but the PIE of all kinds of places is lower,reflects the bad habitat of karst rocky desertification peak cluster. (3)Hyophiletum, Anomodonetum and Racopiletum have the higher ecological dominance and niche breadth in three areas,the niche overlapping of the three bryophyte communities are very high.The results indicated that Hyophiletum,Anomodonetum and Racopiletum have higher adaptation of the three kinds of karst rock desertification,they can live well with the other bryophyte communities in the karst peak cluster rock desertification.
Assessment of the applicability of the WEPP model (Hillslope Version) for soil erosion in karst rock desertification area, Guizhou Province
LONG Ming-zhong, WU Ke-hua, XIONG Kang-ning
2014, 33(2): 201-207.
Abstract PDF(2324KB) icon2123 icon1617
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The Huajiang demonstration area (total area = 47.63 km2) in Guizhou Province was used as a study area to assess the applicability of the WEPP (Hillslope Version) model for soil erosion in karst rock desertification areas. The Huajiang demonstration area, which features typical-canyon in karst plateau, covers both sides of Huajiang river between Guanling county and Zhenfeng county in southwest Guizhou. The demonstration area is in the Panjiang syncline composed of Upper and Middle Triassic carbonates, with lime soil. The soil erosion area is 23.62 km2, that is 49.6 % of the total area, indicating that the soil erosion is serious. Using the runoff plot method and the erosion pin technique, the author monitored and simulated soil loss in the demonstration area in 2006 and 2010 using the WEPP model (Hillslope Version). The applicability of the WEPP model to karst rock desertification areas was assessed by comparing monitoring and simulating data, and the Nash-Sutcliffe coefficient was calculated. The simulation results showed relatively large error and the effective coefficients were negative indicating that the WEPP model is not applicable for direct calculation of the soil erosion modulus in the karst areas of Guizhou. Although the simulation accuracy for soil erosion on micro scale is not sufficient, it generally reflects the different soil erosion intensities between different runoff plots and the relationship between the process of ecological restoration and the changing trend of soil erosion. The application of the WEPP model to soil erosion calculation in karst areas must take into account environmental factors such as underground leakage, rate of bedrock outcropping, and highly broken terrain.
Study of dynamic changes in fractional vegetation coverage in Hechi City in Guangxi karst regions based on TM images
LIANG Zhao-xiong, WANG Xi-zhi, WEI Xing-hu, WANG Ming-chong
2014, 33(2): 208-215.
Abstract PDF(2607KB) icon1720 icon1213
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Hechi City is located in northwest Guangxi Province, one of the most famous karst regions in southwest China with high temperature and precipitation. The area's upper Paleozoic Devonian, Carboniferous, Permian and Triassic carbonate sedimentary rocks have a total thickness of nearly 10,000 meters. The karst topography in Hechi is well developed, concentrated and morphologically diverse. Three periods of the Landsat TM images were selected (1900, 2000 and 2010) to investigate space-time dynamic changes in the fractional vegetation coverage and changes in the karst and non-karst regions, delineation of the different vegetation cover and their change in area according to the dimidiate pixel model based on NDVI. It was shown that during the 20 year period from 1990 to 2010, the area of high vegetation coverage increased from 30.81 % to 53.66 % of the total study area. However, the medium-low, medium and medium-high fractional vegetation coverage areas decreased from 9.63 % to 8.54 %, 17.25 % to 9.88 %, and 31.97 % to 26.74 % respectively during the same period. This shows that, over nearly 20 years, returning farmland to forests in karst regions has been an effective rocky desertification control measure. The change in the area of low fractional vegetation coverage was greater in the karst districts than in the non-karst districts, with change rates of 37.74 % in karst and 3.28 % in non-karst over nearly 20 years. But changes in the area of medinm-low, medium, medium-high and high fractional vegetation coverage were greater in non-karst than in karst, with change rates of 54.3 %, 57.47 %, 26.75 %, 75.77 % in non-karst and 34.84 %, 43.07 %, 16.34 %, 71.55 % in karst. The change in the area of medinm-low and medium fractional vegetation coverage from 1990-2000 was greater than that from 2000-2010, with the change rates of 4.68 %, 0.11 % and 5.68 %, 1.79 % for these two periods. But the change in the area of low and medium-high fractional vegetation coverage from 2000 to 2010 was greater than that from 1990 to 2000, with the change rates of 1.75 %, 5.07 % and 1.64 %, 3.59 % in these two periods. In non-karst, the change in the area of high vegetation coverage from 2000 to 2010 was greater than that from 1990 to 2000, with change rates of 8.38 % from 1990 to 2000 and 16.04 % from 2000 to 2010. The differences in the change of vegetation fraction between karst district and non-karst district are mainly due to differences in lithological conditions.
Study on characteristics and comprehensive evaluation of the fertility of tobacco cultivated soil in Fengdu karst area,Chongqing
LAN Mu-ling, GAO Ming
2014, 33(2): 216-222.
Abstract PDF(1746KB) icon1967 icon1582
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The fertility of limestone soil cultivated with tobacco in karst areas of Fengdu county, Chongqing was studied through field sampling and lab analysis. Methods of principal component analysis and membership function of fuzzy mathematics were used to estimate soil fertility by means of estimating SFI(Soil Feasibility Index). The results showed that: (1) The soil in the area was weakly acidic to neutral. 23.08 % of soil samples had pH less than 5.00, thus there are obvious soil acidification problems in the region. (2) The soil was rich in organic matter and nitrogen. 78.85 % of the soil samples had OM content in the optimum range for planting tobacco (15～30 g/kg). All soil samples had available nitrogen content in a suitable range for planting tobacco (65～100 mg/kg) with a coefficient of variation of only 0.92 %. (3) Total phosphorus content was medium to high (>0.6 g/kg), but there was insufficient supply of available phosphorus in the soil. Phosphorus was absent (<10 mg/kg) in 20.93 % of the soil samples. (4) The soil had an adequate supply of potassium. All samples had rich or extremely rich total potassium content (> 25 g/kg). 81.84 % of the soil samples had available potassium content in the proper range for planting tobacco (>150 mg/kg); (5) The area's overall soil fertility level was not high. Only 15.38 % of samples had medium-high soil fertility (0.70>SFI≥0.60), 57.69 % had medium-low fertility (0.60>SFI≥ 0.40), and 26.93 % had low fertility. Obviously the karst areas are affected by factors including soil erosion and severe degradation,and irrational fertilization. Therefore, in karst areas attention should be given to scientific farming, reduction of soil erosion and degradation, the application of lime to regulate soil pH, and proper increase of the ratio of phosphorous in fertilizer.
Soil fertility evaluation of slope farmland in karst area：A case study of slope farmland in Zhongliang mountain in Chongqing
WU Yu-chun, FU Wa-li, CHENG Hui, CHEN Gao-qi, WEN Zhi-lin
2014, 33(2): 223-230.
Abstract PDF(1086KB) icon1900 icon1216
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Slope farmland is one of the main land-use types in southwest China, and also an important farm land resource in China. However, rocky desertification and soil erosion problems are serious in slope farmland areas, leading to soil fertility degradation. Taking Zhongliang mountain in Chongqing as a case, the soil fertility of slope farmland was evaluated on a small scale by the fuzzy comprehensive index method. According to statistical analysis of sample number rationality, the regional soil fertility evaluation based on 25 soil samples was sufficient to meet the required accuracy of 10 %, 15 % and 20 % relative error at a 90 % confidence level. The minimum data set (MDS) components including soil organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, soil depth and silt/clay were selected by calculating the norm values based on principal components analysis (PCA). Correlation coefficient test between the indicators inside MDS showed that MDS represented maximally all the soil properties with minimal loss of soil fertility information. Membership function was used to transform the indicators into dimensionless data and a weighted summation model was used to calculate the integrated fertility index (IFI). The membership values and IFI reflect the single factor fertility and the integral fertility respectively. This indicated that soil organic matter and total phosphorus were the limiting factors for the soil fertility in the study area, and soil integral fertility was at a medium level with integrated fertility index (IFI) ranging from 0.40 to 0.60.
Heavy metal pollution and toxicity assessment of interstitial water from Laolongdong subterranean river, Chongqing
REN Kun, YANG Ping-heng, DU Wei, SHI Yang, REN Xiao-feng, LI Xiao-chun
2014, 33(2): 231-237.
Abstract PDF(2236KB) icon1868 icon1495
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With increasing urbanization and industrialization, karst subterranean river systems, an important source of drinking water in karst areas, have suffered from various degrees of pollution. Samples of overlying water and interstitial water from surface sediments were collected at the seven sampling sites along the Laolongdong subterranean river in Chongqing karst area during September 2013. Mn concentrations were measured by ICP-OES, and Cu, Cd, Cr, As and Pb were measured by ICP-MS, in order to determine the heavy metal pollution status. The spatial distribution of the heavy metals in the interstitial water and the relationships between metals in different media were studied. Meanwhile, the biological toxicity of the metals in interstitial water was assessed according to the National Recommended Water Quality Criteria released by the EPA. The results showed that the overlying water of Laolongdong subterranean river is not suitable for drinking, as the Mn and Pb levels were higher than limits (Mn≤100 ug/L, Pb≤10 ug/L) established by GB 5749-2006. The concentrations of metals in the interstitial water samples were higher than those in the overlying water samples. This phenomenon probably indicates that the heavy metals may be released from the interstitial water into the overlying water. The concentrations of the studied metals (with the exception of Mn and Pb) in interstitial water decreased from upstream to midstream to downstream locations. Although statistical analysis suggested that there were no significant correlations between the concentrations of these metals occurring in overlying water, with the exception of Mn and As, as well as Cd and Cr, high correlations were found between Cu, Cd, Cr and As in interstitial water. Toxicity assessment of the interstitial water showed that Pb and especially Cr, Cu and Cd, pose acute toxicity to the aquatic ecosystem. However, As does not pose acute toxicity to the aquatic ecosystem.
Distribution of OCPs in underground water and surface sediment of underground river in Chongqing’s Laolongdong
SHI Yang, SUN Yu-chuan, XU Xin, REN Kun, Md.Jahangir Alam
2014, 33(2): 238-247.
Abstract PDF(4530KB) icon2010 icon1223
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In order to study the spatial and temporal distribution of OCPs in surface sediments and different parts of the underground river in Chongqing’s Laolongdong, the concentrations of OCPs residues in water samples were measured with a gas chromatograph equipped with a miro-63Ni electron capture detector. The results showed that the detection rates of OCPs in the water samples and surface sediment in the research area were 100 %. The concentrations of OCPs have obvious seasonal differences. The concentrations of OCPs, DDTs, HCHs in the water are higher during the dry season are than in the rainy season. The OCPs, HCHs concentrations in the surface sediments are higher during the rainy season than in the dry season, but DDTs are higher in the dry season. The concentrations of OCPs in the water are higher downstream than upstream. In contrast, the concentrations of OCPs in the surface sediments are higher upstream than downstream. Due to the lack of sunlight, slow air flow, and less frequent biological activity in the karst cave, the HCHs in the water do not degrade easily, and the difficult release of HCHs from the surface sediment makes their concentrations higher in the cave than outside. In the dry season, under the stable cave conditions the high deposition of DDTs makes DDTs concentrations in water lower underground than at the cave entrance; but during the wet season, dilution due to large amounts of rain makes the DDTs concentrations in water lower at the cave entrance than inside the cave. Under stable cave conditions, it is difficult to release DDTs from cave sediments, and they are largely deposited during the dry season, making DDTs concentrations higher in sediments inside the cave than those outside. The cave environment and different pollution sources (including farmland, factories, etc.)impact the structure of DDTs in water and DDTs, HCHs in surface sediments, but they have little influence on the structure of HCHs in water. In addition, the nature of the pollution sources in different parts of the underground river is connected to the structure of the organochlorine pollutants. Compared with other areas of the world, the concentration of HCHs, DDTs in water and surface sediment of the research area are moderate and high respectively.
Geochemical characteristics of a paleokarst-reservoir in Ordovician Majiagou formation in southern Jingbian tableland
HUO Yong, PANG Qiu-wei, LUO Shun-she, ZHAO Bo-quan, YAO Ya-bin
2014, 33(2): 248-254.
Abstract PDF(2226KB) icon1542 icon1048
Abstract:
The nicer karst reservoirs were formed at the top of the Ordovician Majiagou formation in Ordos basin due to tectonic uplift and erosion during the Caledonian movement.Based on analysis of δ13C and δ18O in dissolution pore fillings, karst breccia cements and carbonate rocks, the results showed that,(1)The δ18O value of various types of rocks is lower than that of the Ordovician seawater in study area while the δ13C value of weak karstification original rock is similar to that of Ordovician seawater;(2)With intensified karstification, the δ18O and δ13C of rocks decreased, and the δ18O value was more sensitive;(3)Fillings in dissolved pore and bedrock formed in the same fluid source, which should be the synsedimentary product of karst. In the paper, based on the values of Sr and the analytic of Sr/Ca, Sr/Ba and B elements which responded to the diagenetic fluid salinity, it may be concluded that there was a large freshwater input into the study area. The low Sr content and high Fe2+/Fe3+ value illustrated that sediments had undergone burial karstification.
Review of and prospects for research on karst cave lighting systems
WENG Zi-fan, YANG Xiao-xia, XIANG Xu, SHI Ding-fang
2014, 33(2): 255-262.
Abstract PDF(1112KB) icon1873 icon2105
Abstract:
With the development of karst cave tourism, lots of artificial lights are introduced into the cave. Cave lighting is helpful for showing the cave space, beautifying the cave environment, making the scenery more attractive and arousing the enthusiasm of visitors. Therefore, cave lighting systems have become important to the research into cave development and protection at home and abroad. Analysis existing research results on cave lighting at home and abroad is beneficial for deeper academic research and directly serves the practical development and protection of karst caves. Through Wanfang Data, CNKI, Springer Link, Elsevier SDOL, EBSCO, Google Scholar, Google, Superstar Academic Discovery System and other databases and search tools, combined with paper documents, 56 articles on cave lighting systems were obtained. Research on cave lighting is mainly focused on seven aspects: the origin and development of cave lighting, the type and choice of light source, the choice and installation of lighting fixtures, the design of cave lighting systems, the operational control of cave lighting systems, the security control of the lighting systems and the cave lighting. Academic research in this field has a long history and diverse research methods. However, the research has some shortcomings. Firstly, the research achievements are excessively limited. Secondly, the research perspectives are too narrow. Thirdly, the general applicability of the research is so weak that there is not yet a systemic theoretical framework. Additionally, the study of cave lighting started late in China and the research development of this area has been much slower than abroad. In the future, the study of cave lighting systems should be focused on the following aspects, systematic research, integration of disciplines, targeted research, establishment of technical standards for karst cave lighting systems, application of new materials and new technology to cave lighting, economy efficiency of cave lighting and the comparative studies of cave light sources.

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