Vertical Distribution Characteristics Research Articles

Characteristics of Modern Geostress and Removability of No. 15 Coal Reservoir, Yangquan Mining Area, China

Based on injection pressure drop test data and acoustic emission test data of 13 records for samples from the Wenjiazhuang and Sijiazhuang mines in the Yangquan mining area, the vertical distribution characteristics of modern in situ stress and its influence on permeability in the Yangquan mining area were analyzed, and the exploitation of the No. 15 coal reservoir was studied. The results show that the Yangquan mining area is a low-stress area within burial depths of 400–760 m, moderate-stress area within 760–950 m, and high-stress area within 950–1300 m. The Yangquan mining area hosts a strike–slip fault stress field within burial depths of 400–900 m and a normal fault stress field within burial depths of 900–1300 m, and the permeability showed a “decrease–increase–decrease” trend with an increase in burial depth. The pressure coefficient K of the modern in situ stress field in the Yangquan mining area decreased with increasing burial depth, and its relationship formula with burial depth was 68.25/H + 0.2846 ≤ K ≤ 397.63/H + 0.6061. The permeability of No. 15 coal seam had a strong logarithmic relationship with horizontal principal stress, a strong exponential relationship with horizontal principal stress difference, and a strong power function relationship with effective stress. With an increase in stress and in stress difference, permeability decreased rapidly. The results of the acoustic emission tests of the No. 15 coal were analyzed. The in situ stress type of the Sijiazhuang mine and Wenjiazhuang mine is the normal fault stress field type, which is consistent with the well test analysis results. The high ring counts in the horizontal direction of coal seam 15 lasted for a long time, which was conducive to the generation of several network-forming fractures in the process of fracturing. The No. 15 coal reservoir is located in strike–slip fault stress field and normal fault stress field areas, and the fractures generated by hydraulic fracturing expanded along the vertical direction and the maximum horizontal principal stress direction, which was favorable for the fracturing transformation of coal reservoirs and the production and development of coalbed methane.

Heavy Metal Contents of Soil and Surface Dust and Its Ecological Risk Analysis in a Multifunctional Industrial Park

A multifunctional industrial park can perform both producing and living functions. The smelting and processing of non-ferrous metals may lead to soil pollution, posing risks to human beings. In this study, an industrial park located in central Anhui Province, China, with copper (Cu) processing and mechanical components as the main industries, was selected as the study object. By collecting and testing soil and dust samples, the horizontal and vertical distribution characteristics of heavy metals in soil and dust in the park were analyzed. The ecological risk index is used to identify areas with higher risks and correlation and principal component analysis are used to disclose the potential source of heavy metals. Results showed that the contents of Cu, Zn, As, Pb, and Cd in the soil were 2.65, 1.76, 1.56, 2.14, and 3.87 times that of the background value, respectively. The heavy metal content of dust was significantly higher than that of soil, with contents of Cr, Ni, Cu, Zn, Hg, As, Pb, and Cd of 1.93, 1.05, 7.57, 4.63, 6.08, 5.39, 2.58, and 5.50 times that of the background value, respectively. Horizontally, the areas with higher ecological risks concentrated in the western part of the park, while vertically there was no significant trend with increases in soil depth. For the dust samples, areas with high ecological risks were closer to the main traffic arteries. Principal component analysis indicated that the main source of heavy metal in western soils was probably irrigation with contaminated river water. Road traffic, on the other hand, is more likely to be the main contributor to high dust heavy metal levels. This result is important for the park to control the potential health risks caused by heavy metals through zoning management according to the functions of different areas.

Study on Soil Moisture Temporal-Spatial Variation and Stability in Loess Plateau of China

Soil moisture temporal-spatial distribution and stability are important factors influencing soil pollutant transport, material migration, regional climate change, hydro-ecological environment as well as agricultural production patterns. According to soil moisture distribution features on the loess plateau, the paper selected three different kinds of surface slopes on the typical experiment sites to carry out soil moisture measurement. The variation coefficient and rank correlation method are proposed to calculate the longitudinal and vertical soil moisture distribution characteristics. The temporal-spatial dynamic features of soil moisture are studied. The present findings show that the soil moisture in the Loess Plateau varies greatly at different soil depths during the period from April to June. The maximum soil moisture appears at the depth of 40-60 cm. The variation coefficient of soil moisture increases with the soil depth. It was discovered that there exists temporal stability at the depth of 20-80cm. The correlation coefficient of soil moisture in different slopes is significant during the period of April-June. The results would play an important support in theoretical research and ecological environment planning, optimization of agricultural planting pattern and comprehensive management of Loess Plateau.

Hydrogeochemistry of fluoride in shallow groundwater of the abandoned Yellow River delta, China

Abstract Fluorosis is the most widespread and serious endemic disease in the abandoned Yellow River flooding delta of East China. One of the important causes of fluorosis is drinking high-fluorine groundwater. In this study, 313 groundwater samples were collected in the central part of the flooding delta to address the chemistry of high-fluoride groundwater, and 33 core samples were collected from one borehole of 150 m depth to analyse the vertical distribution characteristics of total fluorine and water-soluble fluorine. The fluorine concentration in groundwater ranges from 0.2 to 6.7 mg/L, and 72.8% of the samples have fluorine above the China maximum permissible limit of 1.0 mg/L for drinking water. These 313 samples can be divided into nine hydrochemical subtypes, and over 77% of the samples belong to the bicarbonate types. High-fluorine groundwater (over 3.0 mg/L) is generally alkaline water with high HCO3− and low Ca2+. The concentration of water-soluble fluorine decreases gradually with the increase of formation depth, and that in vertical sediment is negatively correlated with Ca2+ and Cl−, but positively correlated with HCO3−. According to the calculation by PHREEQC package, MgF+ and CaF+ are the dominant species controlling the endemic fluorosis of the study area.

Vertical Distribution Characteristics of Outdoor Particles Concentrations in High-Rise Buildings

Vertical Distribution Characteristics of Outdoor Particles Concentrations in High-Rise Buildings

Spreadsheet Tools for Quantifying Seepage Flux Across the GW-SW Interface.

Identifying the spatial distribution and magnitude of seepage flux across the groundwater-surface water (GW-SW) interface is critical for assessing potential impairments and restoration alternatives for water bodies adjacent to sites with groundwater contamination. Measurement of the vertical distribution and time-varying characteristics of temperature in sediments provides an indirect way to map out spatial and temporal patterns of seepage flux into surface water. Two spreadsheet-based calculation tools are introduced that implement four one-dimensional analytical solutions to calculate the magnitude and direction of seepage flux based on measurement of steady-state vertical temperature profiles or transient diel temperature signals at two depths within sediment. Performance of these calculation tools is demonstrated for a pond receiving contaminated groundwater discharge from an adjacent landfill. Transient versus steady-state model performance is compared, and limitations of transient modelsare illustrated for a situation with unfavorable sediment characteristics and inadequate sensor spacing. The availability of a range of analytical solutions implemented within Microsoft Excel® is intended to encourage practitioners to explore use of this seepage flux characterization method and develop greater insight into best practices for model selection and use.

Vertical Distribution Characteristics of Pu Isotopes, <sup>137</sup>Cs and <sup>237</sup>Np in Sediments of Lake Xingkai and the Response to Catchment Environmental Changes

Vertical Distribution Characteristics of Pu Isotopes, <sup>137</sup>Cs and <sup>237</sup>Np in Sediments of Lake Xingkai and the Response to Catchment Environmental Changes

Vertical distribution characteristics of phytoplankton functional groups and their relationships with environmental factors in Lake Basomtso, Tibet, China

Vertical distribution characteristics of phytoplankton functional groups and their relationships with environmental factors in Lake Basomtso, Tibet, China

A Study on rational well spacing for Producing Evaluation and Solution Scheme of the Water Injection in Northern Daqing Blocks

The inter of daqing oil field has already entered the period of high water cut,with the deepening of oil and gas field development technology,the current water flooding development objects in the high and moderate permeableness layers gradually transformed into poor thin layers, such reservoirs with the complicated structure have poor development benefits, but the remaining reserves of several million tons of the demonstrated reserves mainly exist in low permeability poor thin layers. The development well pattern deployment of thin and poor pay zones still have the problems of the imperfectly injection-prodction relation, poor water flooding wells driving, and low producing degree,and it is still difficult to employ the reservoirs with poor development. In order to improve the effect of oil development,and enhance the producing degree of low poor thin reservoirs with permeability,so that it can establish the effective driving energy system,the research on effective producing limitation and technology policy limitation of thin and poor pay zones need to strengthen. Through a lot of research abroad effective producing and rational development technology policy limitation research results on the thin and poor pay zones, based on the basis of previous word, the paper study the microscopic pore structure of thin and poor layers, and compares with the thick reservoirs, while carrying out the research on effective producing limitation and development technology policy limitation of thin and poor layers. On the basis of the standard model fitting the paper analyzed the plane and vertical distribution characteristics of the remaining and also discussed the rational well spacing for producing evaluation.

Characteristics and implication of multilayer dawsonite in heterogeneity reservoir of the Honggang anticline, southern Songliao Basin, NE China

Reservoir heterogeneity is one of the key factors regarding the long-term fate of the injected CO2. Natural CO2 reservoir and ancient CO2-bearing reservoir is a natural analog to investigate the influence of reservoir heterogeneity on the migration of CO2 and CO2-rock interaction with geological timescale. Dawsonite cements are detected in both sandstone and mudstone of the Upper Cretaceous Qingshankou reservoir in Honggang anticline of the southern Songliao Basin, China. Here, we present results of a petrographic characterization of this reservoir based on polarizing microscope, X-ray diffraction, and fluid inclusion data. These data were used to identify the vertical distribution characteristic of dawsonite and to identify the migration characteristics for the supercritical CO2 in heterogeneity reservoir. Our analytical results show that as the “CO2 trace mineral,” dawsonite appears as multilayered zones of cementation that are separated by mudstone interlayers. These multilayered dawsonite could be one of the geological produces for supercritical CO2 flooding through the heterogeneous rock, acting as the lateral migration and upward diffusion. Supercritical CO2 could move through the thinner mudstone interlayer, with the product of dawsonite developing in the mudstone as its “footprint,” although the vertical distance of diffusion in low-permeability caprock is limited. Combined with the truth that most of the present CO2 gas reservoirs (in K1q4) are in the deeper layers than the dawsonite-bearing sandstone (K1q4-K2y1) (developed in non-CO2 reservoir), we can deduce that CO2 was at some time abundant in the Honggang anticline but had now part of CO2 been migrated, with the other part consumed by the reaction with the primary rock and captured as new carbonate minerals. The dawsonite-bearing sandstones also record a sequence of hydrocarbon filling events. Combined with the truth that the injection time of CO2 is later than that of hydrocarbon, the early hydrocarbon should be deasphalted by the injection and migration of mantle CO2. Therefore, CO2 could also be stored as long-term carbonate minerals after the termination of a CO2-EOR project.

Aircraft observations of ice nucleating particles over the Northern China Plain: Two cases studies

While the concentration of ice nucleating particles (INPs) in the cloud layer is more relevant to the cloud processes, most previous measurements of INPs were conducted on the ground. Given the lack of knowledge of vertical distribution characteristics of ice nucleating particles (INPs) over China, airborne measurements focused on the INP vertical profiles were conducted over Northern China Plain on December 27, 2018 and May 12, 2019. The INPs data, sampled from 0.5 to 5.5 km above ground, were analyzed using a static vacuum water vapor diffusion chamber. The observed INP concentration ranges from 0.13 to 10.53 L−1 at nucleation temperature from −17 to −26 °C and generally decreases with height. In addition, the large aerosols (>0.5 μm) sampled at higher altitudes have a better ice nucleation capacity based on the vertical distribution of activated fractions. The INPs sampled in the low humidity area show a strong correlation (R2 > 0.7) with aerosol particles larger than 0.5 μm in diameter, indicating that the number concentration of large aerosols (>0.5 μm) is an important parameter in INP concentration parameterization at high altitudes.

Risk analysis of natural hydraulic fracturing in an overpressured basin with mud diapirs: A case study from the Yinggehai Basin, South China sea

The Yinggehai Basin is a strongly overpressured basin without large-scale faults in the Central Depression Zone. The hydraulic seal capacity of the caprocks over geological history has been the key factor controlling the vertical distribution characteristics of oil and gas. Based on leak-off data, rock mechanics tests and measured pore pressure data, this paper analyses the potential of natural hydraulic fracturing with the fault analysis seal technology (FAST) methodology for caprocks C1 (caprock of the Huangliu Formation) and C2 (caprock of the Meishan Formation) of the diapir belt in the north Central Depression Zone and determines the failure mode and gas sealing capacity of the two caprocks. The results show that gas leakage occurred continuously in both C1 and C2 in the diapir zone (DZ) throughout geological time. However, far from the diapir zone (FDZ), hydraulic leakage occurred only in caprock C2 while no leakage occurred in caprock C1 over geological time. These results are consistent with the gas accumulation that occurred in both the Yinggehai Formation and Huangliu Formation in the DZ but only in the Huangliu Formation in the FDZ. A relatively reasonable explanation is that diapirism promoted natural hydraulic fracture development via the following effects: (i) Diapirism transfers deep overpressure to shallow layers and increases the pressure gradient; (ii) The high-angle fractures associated with diapirism reduce the critical stress condition for the occurrence of natural hydraulic fracturing; and (iii) Diapirism results in the formation of dome structures in shallow layers, causing more shallow burial of caprock in the DZ than the FDZ. Shallowly buried caprocks, which have a relatively lower hydraulic fracture pressure, facilitate gas migration. These effects promoted natural hydraulic fracturing in the DZ, which is the main reason for the difference in the vertical distribution of gas reservoirs between the DZ and FDZ.

Estimating the Probable Maximum Precipitation by Physical Methods Using Satellite and Radiolocation Observation Data: Case Study of the Middle Urals

The study considers the methods for evaluating the maximal possible daily storm rainfall (MPR) in the Middle Ural based on a combination of ground, aerological, satellite, and radiolocation data. The methods under consideration represent an alternative to statistical estimation approaches. MPR is evaluated using the total moisture content of cloud systems, described in terms of their stationarity or dynamics over time. The considered methods include evaluating moisture content based on the characteristics of vertical temperature distribution in the troposphere, convection rate, and the height of the upper cloud boundary. The estimates of the probable maximum precipitation, made for the conditions of stable or cloud-dependent moisture content, are comparable with the maximums evaluated by Hershfield statistical method. The probable maximums determined by physical methods are close to the values with exceedance probability of 0.01–0.001%, evaluated with the use of lognormal distribution. The method for evaluating the probable maximum precipitation can be used in engineering practice.

Vertical distribution, population structure and developmental characteristics of the less studied but globally distributed mesopelagic copepod Scaphocalanus magnus in the western Arctic Ocean

Abstract Scaphocalanus magnus is a large copepod species with a worldwide distribution. Information on the ecology of this species is scarce. In this study, S. magnus was collected using vertically stratified net sampling from an ice station in the western Arctic Ocean over a year. The vertical distribution differed between periods of polar night and midnight sun, with core depth distributions of 264–381 m for the polar night and 518–745 m for the midnight sun. The shallower distribution during the polar night may have resulted from the animals moving upwards to find sufficient food during the less productive season. The abundance of early copepodite stages showed clear seasonality. The C2 and C3 stages were abundant June–August and August–September, respectively. After C4, seasonality in abundance was not clear. For C4 and C5, body sizes and masses were greater for males than for females while the opposite was the case for C6. Adult males do not feed and thus have shorter life spans than females, skewing the adult sex ratio towards females. For these mesopelagic particle feeding copepods, a long residence time at C6F suggests that in a varying food environment, it is possible to wait to initiate reproduction until favourable food conditions occur.

Ecological Risk Assessment of Heavy Metals in the Vicinity of Tungsten Mining Areas, Southern Jiangxi Province

ABSTRACT A field survey was performed to investigate the metals contamination in the vicinity of tungsten mining areas. Ten sampling sites alongside perennial wind direction were selected for soil collection and heavy metal contents determination, include Cr, Cu, Zn, Pb, As, Cd, and W. Horizontal and vertical distribution characteristics of metals were performed. Geo-accumulation and potential ecological risk of soil samples were discussed for a description of risk assessment. The results showed that the mean concentrations of all metals in soil samples exceeded the background value of Jiangxi background. The heavy metal contents in vertical profiles revealed the surface accumulation of Cd, W, and Pb, while, As increased as soil depth increased. The geo-accumulation index shown the highest pollution level of W and followed by Cd. Single ecological risk factor () figured out that the contamination degree followed the sequence of Cd>As>W>Zn>Pb>Cr>Cu. Furthermore, the potential ecological risk index () was calculated for risk level assessment, and Cd takes account the most contribution in surface soil, followed by W and As.

The Horizontal and Vertical Distribution of Nutrients and the Potential Eutrophication Assessment in the Yellow River Estuary in Dry Season

Yu, X.; Li, B.; Wang, T.; Liu, Y.; Zhan, C., and Cui, B., 2020. The horizontal and vertical distribution of nutrients and the potential eutrophication assessment in the Yellow River estuary in dry season. In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 208–213. Coconut Creek (Florida), ISSN 0749-0208.Terrigenous nutrients discharged into seawater played an important role in controlling the marine primary productivity. Study on the horizontal and vertical distribution characteristics of nutrients was essential in eutrophication and sea-air exchange study. In this paper, the nutrient concentrations and their distribution in the surface microlayer and three sub-surface layers of the Yellow River estuary were measured. The horizontal and vertical distribution characteristic of nutrients was analyzed, so did the potential eutrophication assessment and the nutrient enrichment of the surface microlayer. The results showed that nutrient concentrations decreased from the estuary to the shore horizontally. NH4+-N and NO2--N increased vertically. NO3--N and PO43-P decreased vertically. Eutrophication occurred in the micro-layer and the sub-surfaces. The Yellow River estuary suffered an eutrophication outbreak risk. The enrichment of NH4+-N, NO3--N and NO2--N was significant in April 2018, nor did PO43--P.

Vertical Distribution Characteristics of Dissolved Oxygen and Chlorophyll a in Typical Tributaries During the Impoundment Period of the Three Gorges Reservoir

The water quality of the backwater areas in the Xiangxi River and Shennong River, which are typical tributaries of the Three Gorges Reservoir, was monitored in September 2018. The vertical distribution characteristics of dissolved oxygen, chlorophyll a, and other indicators in the two rivers were analyzed and compared, and the environmental factors affecting their vertical distribution were discussed. The results showed that the dissolved oxygen concentration 0-10 m and 0-12 m from the surface of the Xiangxi River and Shennong River, respectively, showed significant stratification and decreased with increasing water depth. The dissolved oxygen saturation of surface water was 139.20% and 107.78%, respectively, reaching a state of supersaturation (SDO>100%).The dissolved oxygen concentration in the middle and bottom water was more stable without stratification. The vertical distribution characteristics of chlorophyll a were consistent with those of dissolved oxygen in the Xiangxi River and Shennong River, and the chlorophyll a concentration in the surface water showed moderate eutrophication (5μg·L-1 < Chl-a < 20 μg·L-1). According to Pearson correlation analysis, the vertical distribution of dissolved oxygen in the Xiangxi River and Shennong River was significantly correlated with that of water temperature and phytoplankton. The stratification of water temperature and the life activities of phytoplankton were the key factors affecting the vertical distribution of dissolved oxygen. Chlorophyll a was positively correlated with water temperature and pH, and negatively correlated with turbidity, indicating that the vertical distribution of phytoplankton was mainly affected by the attenuation of light intensity along the water depth and the stratification of water temperature.

Vertical distribution characteristics of plant community in shady slope of degraded tiankeng talus: A case study of Zhanyi Shenxiantang in Yunnan, China

We investigated the characteristics of plant species diversity in tree and shurb layers and the main influencing factors in different slope positions of a shady slope of degraded tiankeng talus. The results showed that there were 21 species in 17 genera and 13 families in the tree layer, and 20 species in 20 genera and 14 families in shrub layer in the south side of the Shenxiantang. Plant communities were subtropical moist coniferous and broad-leaved mixed forest. Micro-climate led to obvious vegetation variation between the pit and the pit slope at the tiankeng. The secondary collapse over the talus with mid-slope could conserve more water, which supported the water-demanding species in a high-quality niche. All the α diversity indices including Margalef (3.58), Shannon (2.47), Simpson (0.79) and Pielou (0.86) reached the maximum at the pit bottom edge with slight variability, and the maximum coefficient of variation was only 0.226. The β diversity index fluctuated greatly among the pit-pit, slope-pit, bottom edge. The Routledge and Whilson-Shmida indices showed the trends of decrease-increase-decrease, with the maximum values of 15.95 and 1.20, respectively. Species turnover demonstrated the upward trend overall, and the number of co-species was decreased. Plant diversity on each slope position was mainly related to the contents of total nitrogen, total phosphorus, available phosphorus and organic carbon in soil. Soil was the most important factor leading to the difference among slope positions.

Characteristics of Vertical Spatial Distribution of Dust Particles in Radio Frequency-Plasma Sheath

The vertical spatial distribution of dust particles in radio frequency (RF) discharge plasma sheath is studied. The dust particles are levitated above the powered electrode in the discharge. From the distribution of the dust particles of different sizes generated by mixing of suitable gases, the effect of changing the RF power on the dust cloud behavior is studied. It is found that the distribution of the different sized dust particles in the sheath with variable bias differs significantly from that of single sized dust particles with fixed bias. As the RF power increases, the distribution range as well as the levitation height of the dust cloud above the powered electrode decrease. A theory for the observed results is also given. Based on the experimental and numerical results, we attribute the observed dependence to a combination of the enhanced sheath electric field and the ion drag force, but the decrease of the sheath thickness with increase of the discharge power has only minor contribution.

Vertical Distribution of Soil Dissolved Carbon and Its Influencing Factors in the Artificial Shelterbelt Irrigated with Saline Water in an Extreme Drought Desert

Dissolved carbon (DC) is the most active carbon fraction in soils. Vegetation restoration and reconstruction accelerate the carbon cycle in arid desert regions. Studying the DC distribution in soil profiles of artificial shelterbelt under saline irrigation can provide theoretical support and decision-making basis for artificial shelterbelt management, development, and utilization in arid desert areas. In this study, we took the artificial shelterbelts drip-irrigated with five different mineralization and one shifting sandy land (CK) along the Taklimakan Desert Highway as sampling plots, analyzed and discussed the vertical distribution characteristics of soil dissolved organic carbon (SDOC) and dissolved inorganic carbon (SDIC) in the 0-1 m profiles, and further analyzed their relationships among different factors. The results showed that SDOC and SDIC of CK and shelterbelts under 2.82 g·L-1 irrigation showed an "I" type distribution with a linear function relationship. The SDOC and SDIC of four other treatments showed a "Γ" type distribution with power function relationships. The fluctuation ability and contribution degree of SDOC and SDIC of different treatments in the surface layer were higher than those in the lower layers, and the fluctuation and contribution intensity of SDOC were higher than those of SDIC. Except for 2.82 g·L-1 treatment, the average SDOC contents of other treatments were 2-4 times those of SDIC. The average SDOC content of 2.82 g·L-1 treatment was lower than CK; other treatments were 3-5 times that of CK; and the average SDIC content of all treatments increased 15.0%-57.9% than CK. For the 0-5 cm layer, SDOC content increased with the irrigation water mineralization except the 2.82 g·L-1 treatment, but SDIC content firstly increased and then decreased with increasing mineralization, and that for the 4.82 g·L-1 treatment was highest. The SDOC and SDIC were positively correlated with EC, SOC, irrigation water mineralization, SIC, and soil moisture, for which they both showed a weak positive correlation with soil moisture; they were negatively correlated with soil depth. The SDOC and SDIC showed a weak negative correlation and a weak positive correlation with pH, respectively. In summary, the mineralization of irrigation water has an important impact on the vertical distribution of SDOC and SDIC, and their distribution also has close relationships with EC, SOC, SIC, soil moisture, and soil depth, which is of great significance for plantations in extremely drought deserts.