贵州喀斯特地貌畜禽粪污综合利用方式研究

为有效提升喀斯特地貌下畜禽粪污综合利用率,本文阐述了喀斯特地貌下畜禽粪污综合利用存在的问题,提出了利用统筹兼顾,多形式推进利用、优化完善机制,注重配合协调、利用技术支撑,促进粪污利率、注重政策及资金扶持,强化综合利用力度这几个对策,提供给相关人员参考。

不同岩性土壤养分对广玉兰幼苗的影响

以广玉兰幼苗为试材,采用生态学方法,研究了喀斯特地区6种不同岩性的土壤与广玉兰幼苗养分含量间的变化和影响,以期为喀斯特地区广玉兰幼苗的培育、生长和施肥提供参考依据。结果表明:在不同岩性的土壤上,土壤养分及广玉兰幼苗体内营养元素含量之间均存在显著差异;在不同岩性的土壤上,广玉兰幼苗对土壤有效养分的吸收在石英砂岩上最好,在第四纪红色粘土上最差;广玉兰幼苗在其整个生长过程中,对氮素和磷素的吸收较多,对钾素的吸收则相对较少。

Survey of the use by birds of various karst wetlands in southwestern Guangxi, southern China

The limestone area located in southwestern Guangxi in the south of China is part of a global biodiversity hotspot. As an important habitat of this limestone region, karst wetlands provide birds with necessary water conditions for their survival and reproduction. From 2007 to 2012, bird surveys were conducted in natural wetlands(pools, streams, springs and seasonal flows) in 14 nature reserves and 18 reservoirs in the limestone area of southwestern Guangxi. A total of 365 bird species were recorded in field investigations, including 103 water-dependent birds mainly seen in wetlands. Among these 103 birds, 10 species are globally threatened and 5 species have been placed under national key protection. The birds were selective in their use of the various types of karst wetlands. The number of bird species was the highest in pools and springs, with 304 and 266 respectively, followed by streams with 131 species. Reservoirs are the main wintering habitat for the large Natatores and in the rainy season the importance of seasonal flows is paramount. Seasonal changes in the utilization of karst wetlands by birds were obvious; the number of bird species in the dry season was much higher than during the rainy season. Bird migration and seasonal flows are the main reasons for seasonal variation in the number of water-dependent birds. These natural karst wetlands ensure the drinking water supply for more than 80% of the water-independent birds in the dry season. These karst wetlands are the wintering ground and stopover area for 58 species of migrant birds. At present, threats to the birds in the karst wetlands consist of illegal hunting, habitat changes and eucalyptus plantations. Karst wetlands are important for protecting biodiversity. More attention ought to be directed to these wetlands and protection efforts enhanced.

Cultivation Techniques for High-yield Corn in a Karst Area of Southwest Guizhou

The cultivation techniques for high-yield corn in a karst area of southwest Guizhou were elaborated in this research from the respects of choosing farmland, preparing farmland, picking good seeds, timely sowing, rational close planting, im-proving the quality of planting, mulching, scientific fertilization, field management, timely harvest, etc. we hoped to provide a reference for the realization of high-effi-ciency corn planting in mountain areas.

Safety thickness analysis of tunnel floor in karst region based on catastrophe theory

Based on the tunnel shape, span and depth, the previous elliptical plate model and clamped beam model were modified.The modified model was applied to different situations. For the elliptical plate model, the water effects were considered. For the clamped beam model, water and horizontal stress were considered. Corresponding potential functions and cusp catastrophe models of rock system were established based on the catastrophe theory. The expressions of critical safety thickness were derived with necessary and sufficient conditions. The method was applied to the practical engineering. Some parameters related to the stability were discussed. The results show that elastic modulus and thickness are advantageous to the floor stability, and that the load, span,horizontal stress and water are disadvantageous to the floor stability.

Minimum safe thickness of rock plug in karst tunnel according to upper bound theorem

High pressure and water-bearing caverns ahead of a karst tunnel face tend to cause geological disasters, such as water and mud bursts. So, the determination of safe thickness of the reserved rock plug is a key technical problem to be solved for karst tunnel construction. Based on the Hoek-Brown nonlinear failure criterion, the minimum safe thickness of rock plug was investigated in the light of the limit analysis theory. On the basis of the proposed failure mode, the expression of the minimum thickness for rock plug was obtained by means of upper bound theorem in combination with variational principle. The calculation results show the influence of each parameter on safe thickness and reveal the damage range of rock plug. The proposed method is verified by comparing the results with those of the drain cavern of Maluqing Tunnel. The research shows that with the increase of compressive strength and tensile strength as well as constant A of Hoek-Brown criterion, the safe thickness decreases, whereas with the increase of cavern pressure, tunnel diameter, and constant B from Hoek-Brown criterion, the safe thickness increases. Besides, the tensile strength, or constants A and B affect the shear failure angle of rock plug structure, but other parameters do not. In conclusion, the proposed method can predict the minimum safe thickness of rock plug, and is useful for water burst study and prevention measures of tunnels constructed in high-risk karst regions.

Effects of Land Cover on Soil Organic Carbon Stock in a Karst Landscape with Discontinuous Soil Distribution

Land cover type is critical for soil organic carbon （SOC） stocks in territorial ecosystems. However, impacts of land cover on SOC stocks in a karst landscape are not fully understood due to discontinuous soil distribution. In this study, considering soil distribution, SOC content and density were investigated along positive successional stages （cropland, plantation, grassland, scrubland, secondary forest, and primary forest） to determine the effects of land cover type on SOC stocks in a subtropical karst area. The proportion of continuous soil on the ground surface under different land cover types ranged between 0.0% and 79.8%. As land cover types changed across the positive successional stages, SOC content in both the 0-20 cm and 20-50 cm soil layers increased significantly. SOC density （SOCD） within O-lOO cm soil depth ranged from 1.45 to 8.72 kg m^-2, and increased from secondary forest to primary forest, plantation, grassland, scrubland, and cropland, due to discontinuous soil distribution. Discontinuous soil distribution had a negative effect on 8OC stocks, highlighting the necessity for accurate determination of soil distribution in karst areas. Generally, ecological restoration had positive impacts on SOC accumulation in karst areas, but this is a slow process. In the short term, the conversion of croplandto grassland was found to be the most efficient way for SOC sequestration.

Spatial Heterogeneity of Soil Mineral Oxide Components in Depression Between Karst Hills,Southwest China

In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.

Responses of Spatial-temporal Variation of Karst Ecosystem Service Values to Landscape Pattern in Northwest of Guangxi,China

The responses of spatiotemporal variation of ecosystem service values (ESVs) to landscape pattern from 1985 to 2005 in a typical Karst area of the northwest Guangxi Zhuang Autonomous Region,China,were examined us-ing remote sensing and geographic information system techniques in this paper.The total ecosystem service values de-clined significantly from 1985 to 1990,and then increased slowly from 1990 to 2005,almost equaled to the 1985 level.The ecosystem service values tended to decline from the west to the east and from mountainous regions to peak-cluster depression areas in 1985,1990,2000 and 2005 respectively.During the period from 1985 to 2005,the ecosystem ser-vice values have increased in the middle and eastern parts of the study area.Landscape pattern indices,such as total area,largest patch index,contagion,aggregative index,effective mesh and proportion of like adjacencies,are significantly correlated with ecosystem service values.This suggests that ecosystem service values tend to increase with the growth of patch area and patch connectivity.However,there are negative correlations between ecosystem service values and landscape pattern indices,such as division index and patch richness.It indicates that ecosystem service values decrease with patch fragmentation and patch size shrinkage.The ecosystem conditions in the typical Karst area have been improved because of the control measures of rocky desertification.It is important to protect key landscape types,such as woodland,shrub and grassland,and to increase patch size and connectivity to avoid further fragmentation.Furthermore,it is necessary to reduce disturbances to ensure the growth of ecosystem service values and to facilitate the sustainable development in this region.

Modified Method for Estimating Organic Carbon Density in Discontinuous Karst Soil Using Ground-Penetrating Radar and Geostatistics

The conventional method which assumes the soil distribution is continuous was unsuitable for estimating soil organic carbon density(SOCD) in Karst areas because of its discontinuous soil distribution. The accurate estimation of SOCD in Karst areas is essential for carbon sequestration assessment in China. In this study, a modified method,which considers the vertical proportion of soil area in the profile when calculating the SOCD, was developed to estimate the SOCD in a typical Karst peak-cluster depression area in southwest China. In the modified method, ground-penetrating radar(GPR) technology was used to detect the distribution and thickness of soil. The accuracy of the method was confirmed through comparison with the data obtained using a validation method, in which the soil thickness was measured by excavation. In comparison with the conventional method and average-soil-depth method,the SOCD estimated using the GPR method showed the minimum relative error with respect to that obtained using the validation method. At a regional scale, the average SOCDs at depths of 0-20 cm and 0-100 cm, which were interpolated by ordinary kriging,were 1.49(ranging from 0.03-5.65) and 2.26(0.09-11.60) kgm-2based on GPR method in our study area(covering 393.6 hm2), respectively. Therefore, the modified method can be applied on the accurate estimation of SOCD in discontinuous soil areas such as Karst regions.

Characteristics of heavy metals in soils under different land use in a typical karst area, Southwest China

This study investigated the distribution of six pollutant elements(Cr, Cu, Pb, Zn, Cd, and As), and their relationship to soil organic carbon(SOC) in five soil profiles in the Puding area. Results show SOC content decreased exponentially to the depth of soil profiles; the vertical distribution patterns of SOC in soil profiles were partially controlled by land use. The concentrations of these pollutant elements in most soils were lower than background values, indicating that the local soil was less likely to be contaminated by foreign inputs. Geo-accumulation index values of these elements in most soil samples were less than 1, suggesting that the soil of this area may not be polluted. The concentrations of Cr, Cu, As, and Zn in soils from all land use types were significantly negatively correlated with SOC contents. Geochemical approaches confirmed that the soil of this area was less influenced by pollutant elements.

Spatial-temporal Changes of Vegetation Cover in Guizhou Province, Southern China

Guizhou Province is an important karst area in the world and a fragile ecological area in China. Ecological risk assessment is very necessary to be conducted in this region. This study investigates different characteristics of the spatial-temporal changes of vegetation cover in Guizhou Province of Southern China using the data set of SPOT VEGETATION(1999–2015) at spatial resolution of 1-km and temporal resolution of 10-day. The coefficient of variation, the Theil-Sen median trend analysis, and the Mann-Kendall test are used to investigate the spatial-temporal change of vegetation cover and its future trend. Results show that: 1) the spatial distribution pattern of vegetation cover in Guizhou Plateau is high in the east whereas low in the west. The average annual normalized difference vegetation index(NDVI) from west to east is higher than that from south to north. 2) Average annual NDVI improved obviously in the past 17 years. The growth rate of average annual NDVI is 0.028/10 yr, which is slower than that of vegetation in the country(0.048/10 yr) from 1998 to 2007. Average annual NDVI in karst area is lower than that in non-karst area. However, the growing rate of average annual NDVI in karst area(0.030/10 yr) is faster than that in non-karst area(0.023/10 yr), indicating that vegetation coverage increases more rapidly in karst area. 3) Vegetation coverage in the study area is stable overall, but fluctuates in the local scales. 4) Vegetation coverage presents a continuous increasing trend. The Hurst exponent of NDVI in different vegetation types has an obvious threshold in various elevations. 5) The proportion of vegetation cover with sustainable increase is higher than that of vegetation cover with sustainable decrease. The improvement in vegetation cover may expand to most parts of the study area.

The importance of non-carbonate mineral weathering as a soil formation mechanism within a karst weathering profile in the SPECTRA Critical Zone Observatory, Guizhou Province,China

Soil degradation, including rocky desertification,of the karst regions in China is severe. Karst landscapes are especially sensitive to soil degradation as carbonate rocks are nutrient-poor and easily eroded. Understanding the balance between soil formation and soil erosion is critical for long-term soil sustainability, yet little is known about the initial soil forming processes on karst terrain. Herein we examine the initial weathering processes of several types of carbonate bedrock containing varying amounts of non-carbonate minerals in the SPECTRA Critical Zone Observatory, Guizhou Province, Southwest China. We compared the weathering mechanisms of the bedrock to the mass transfer of mineral nutrients in a soil profile developed on these rocks and found that soil formation and nutrient contents are strongly dependent upon the weathering of interbedded layers of more silicate-rich bedrock(marls). Atmospheric inputs from dust were also detected.

Effects of organic mineral fertiliser on heavy metal migration and potential carbon sink in soils in a karst region

Heavy metal pollution in karst mountainous area of Guizhou has spread due to the long-term exploitation of mineral resources and the improper disposal of environmentally hazardous waste. Heavy metals are characterised by non-degradation, strong toxicity, and constant accumulation, posing a grave threat to karst mountain fragile soil ecosystem. To reduce the harm caused by heavy metal pollution and damage to agricultural products, research was undertaken on the basis of previous work by simulating pot experiments on pak choi cabbage(Brassica rapa chinensis)planted in Cd-contaminated soil: different amounts of organic mineral fertilisers(OMF) compared with chemical fertiliser(CF) were used and by detecting the amount of heavy metal in the mature vegetable, a better fertilisation strategy was developed. The results showed that the Cd content in vegetables grown with CF was 23.70 mg/kg,while that of vegetables grown with OMF and bacterial inoculant was the lowest at 15.13 mg/kg. This suggests that the use of OMF and microbes in karst areas not only promotes plant growth but also hinders plant absorption of heavy metal ions in the soil. In addition, through the collection of pot leachate, the detection of water chemistrycharacteristics, and the calculation of the calcite saturation index, it was found that the OMF method also induces certain carbon sink effects. The results provide a new way in which rationalise the use of OMFs in karst areas to alleviate soil heavy metal pollution and increase soil carbon sequestration.

Role of hydro-geochemical functions on karst critical zone hydrology for sustainability of water resources and ecology in Southwest China

Focusing on sustainability of water resources and ecology in the complex karst critical zone, we illustrated functions of the hydro-geochemical analysis on hydrology from the aspects of connection and interaction among hydrology–vegetation–soils/rock fractures along the karst subsurface profile. We reviewed isotopic and geochemical interpretations on tracing water sources for plant uptake, quantifying watershed outlet flow composition and residence times, and evaluating long-term evolution among climate–landscape–hydrology in the karst critical zone. In this paper, the application of the hydro-geochemical analysis on the above aspects in the karst areas of southwest China was summarized.

Characteristics and distributions of humic acids in two soil profiles of the southwest China Karst area

Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their evolutions in different soils of the study area. The results showed that characteristics and distribution of SOM along the two soil profiles were notably different. Total organic carbon(TOC) contents of soil samples decreased just slightly along the limestone soil profile but sharply along the yellow soil profile. TOCs of the limestone soils were significantly higher than those of the corresponding yellow soils, and C/N ratios of SOMs showed a similar variation trend to that of TOCs, indicating that SOM can be better conserved in the limestone soil than in the yellow soil. The soil humic acids were exhaustively extracted and further fractionated according to their apparent molecular weights using ultrafiltration techniques to explore underlying conservation mechanisms. The result showed that C/N ratios of HAs from different limestone soil layers were relatively stable and that large molecular HA fractions predominated the bulk HA of the top soil, indicating that HA in the limestone profile was protected while bio and chemical degradations were retarded. Combined with organic elements contents and mineral contents of two soils, weconcluded that high calcium contents in limestone soils may play a key role in SOM conservation by forming complexation compounds with HAs or/and enclosing SOMs with hypergene CaCO_3 precipitation.

Numerical simulation of groundwater under complex karst conditions and the prediction of roadway gushing in a coal mine:a case study in the Guang'an Longtan Reservoir in Sichuan Province, China

Numerical simulation of groundwater in karst areas has long been restricted by the difficulty of generalizing the hydrogeological conditions of reservoirs and of determining the relevant parameters due to the anisotropy and discontinuity of the karst water-bearing media in these areas. In this study, we used the Guang'an Longtan Coal mine in Sichuan as an example, and generalized the complex hydrogeological conditions in the reservoir area. A finite element numerical flow model was used to simulate current and future scenarios of roadway gushing at the bottom of the coal mine at pile number 1 + 700 m. The results show that the roadway section corresponding to valleys has a gushing quantity of 4323.8–4551.25 m^3/d before impoundment. Modeled water inflow after impoundment increased to 1.6 times the water inflow before impoundment, which threatens the impoundment as well as the roadway's normal operation. Therefore, roadway processing measures are needed to guarantee the safety of the impoundment and of the mining operation.

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.

Hydrodynamic characteristics of Wujiangdu Reservoir during the dry season-a case study of a canyon reservoir

With the development of hydropower in the karst area of Southwest China, a series of cascade canyon reservoirs have been formed through the construction of dams. Given that hydrodynamic conditions in canyon reservoirs play a pivotal role in controlling the spatiotemporal distribution of physical and chemical properties of the stored water, hydrodynamic characteristics are of great importance in understanding biogeochemical cycles in those reservoirs. To further this understanding, a field campaign was conducted in the Wujiangdu Reservoir of Guizhou Province. It was found that from the reservoir inlet to the front of the dam, velocity(v) was negativelycorrelated and had a logarithmic relationship with distance along the ship track(s) under dry-season flow conditions[v =-0.104 ln(s) + 0.4756]. Analysis showed that dryseason flow velocity had no significant correlation with water temperature, p H, or dissolved oxygen(DO). However, when velocity decreased to 0.061 m/s, water depth increased abruptly. In addition, DO displayed a sudden drop and the trend in p H changed from increasing to decreasing, while water temperature showed an opposite trend, indicating the existence of a transition zone from the river to the reservoir.

Application of TSD tunnel seismic prediction system in karst area

TSD is one of the classical methods of tunnel seismic prediction based on higher accuracy multi-wave multi-component seismology.The working principle of the TSD and an application example of the TSD on tunnel prediction in Chongqing are introduced in this paper.This system has two ports for speed signal and acceleration signal,and the equipment is more portable and easy to use.According to the application results we can conclude that the TSD prediction system is accurate and it has the wide application prospect in tunnel seismic detection.