Experimental Study of Coal–Gas Outburst: Insights from Coal–Rock Structure,Gas Pressure and Adsorptivity

Natural Resources Research - Coal–gas outburst is a complex dynamic phenomenon in underground coal mines that has occurred frequently over the past 150 years. This phenomenon has...     

A Thermo–Hydro–Mechanical Model: Capturing the Effects of Initial Permeability and Gas Pressure on Outburst-Prone Indicators

Natural Resources Research - Coal and gas outbursts often result in a large number of casualties and economic losses. Its complex processes involve the multi-field coupling of gas flow, coal...     

Kinetic Characteristics of CH4 Adsorption on Coals under Variable Temperature–Pressure Coupling Interaction

Natural Resources Research - The accurate determination of coalbed methane (CBM) content is of great significance for its development and utilization as well as for the prevention and control of...     

Assessment of Nitrate—Nitrogen Distribution in Kansas Groundwater, 1990–1998

Nitrate-nitrogen (nitrate-N) in groundwater is a potential problem in many parts of Kansas.From 1990 to 1998, 747 water samples were collected from domestic, irrigation, monitoring,and public water supply wells primarily from the western two-thirds of the state, and analyzedfor nitrate-N by the Kansas Geological Survey. Nitrate-N concentrations of the 747 samplesanalyzed range from 29% with less than or equal to 3 mg/L, 51% between 3 and 10 mg/L,and 20% greater than or equal to 10 mg/L. Factors that show a statistically significantrelationship with the occurrence of nitrate-N in Kansas groundwater in this assessment includegeographic area of the state, depth of well, and age of well. Nitrate-N levels of wells screenedin the High Plains aquifer in south-central Kansas showed a statistically higher concentrationthan samples collected from the High Plains aquifer in the western portion of the state.Comparison of nitrate-N with depth of well indicated that shallower wells throughout the stategenerally have higher nitrate-N values than deeper wells. Irrigation wells older than 1975showed statistically higher nitrate-N concentration than wells installed during and since 1975,possibly related to changes in well-construction practices and regulations that occurred in 1975.     

Are There Differences in the Response of Natural Stand and Plantation Biomass to Changes in Temperature and Precipitation? A Case for Two-needled Pines in Eurasia

A comparative discussion of the advantages and disadvantages of natural stands and plantations, including in terms of their productivity and stability, began from the moment of the first forest plantings and continues to this day. In the context of the progressive replacement of natural forests by plantations due to deforestation, the question of how will change the carbon storage capacity of forest cover when replacing natural forests with artificial ones in a changing climate becomes extremely relevant. This article presents the first attempt to answer this question at the transcontinental level on a special case for two-needled pine trees (subgenus Pinus L.). The research was carried out using the database compiled by the authors on the single-tree biomass structure of forest-forming species of Eurasia, in particular, data of 1880 and 1967 of natural and plantation trees, respectively. Multi-factor regression models are calculated after combining the matrix of initial data on the structure of tree biomass with the mean January temperature and mean annual precipitation, and their adequacy indices allow us to consider them reproducible. It is found that the aboveground and stem biomass of equal-sized and equal-aged natural and plantation trees increases as the January temperature and precipitation rise. This pattern is only partially valid for the branches biomass, and it has a specific character for the foliage one. The biomass of all components of plantation trees is higher than that of natural trees, but the percent of this excess varies among different components and depends on the level of January temperatures, but does not depend at all on the level of annual precipitation. A number of uncertainties that arose during the modeling process, as well as the preliminary nature of the obtained regularities, are noted.     

Measuring Space–Time Access to Food Retailers: A Case of Temporal Access Disparity in Franklin County,Ohio

Typical measures of food access use spatial-only methods to identify nearby food outlets and the quantity, quality, and variety of food available. This measure of spatial access falls short in explaining the effect that the operating hours of food retailers have on food access. Our study aims to complement the spatial dimension of access measures by bringing time in as a new constraint on food access. To this end, we developed three measures of spatial, temporal, and spatiotemporal access and correlated these measures with socioeconomic status (SES) in a case in Columbus, Ohio. Findings from our analysis of food access disparity suggest that low-SES neighborhoods in Columbus are not at a disadvantage of spatial access, but their limited temporal access is a more pressing concern. Implications drawn from the study would assist community advocates, local governments, and other stakeholders in deriving a better understanding of the local foodscape that are not only mediated by space but also time.     

Comparative Analysis of Gas–Solid–Liquid Coupling Behavior in Front of the Working Face Before and After Water Injection During Coal Mining

Natural Resources Research - Coal seam water injection is a critical measure for the prevention of coal-and-gas outbursts. However, the gas–solid–liquid coupling effect in front of the...     

Evaluation of Changes in Expected Ultimate Recovery for US Gulf of Mexico Oil and Gas Fields, 1975–2016

Natural Resources Research - Quantifying the change in field expected ultimate recovery across time is an old and complex topic fraught with ambiguity and misinterpretation. In this paper, changes...     

Application of AdaBoost Algorithms in Fe Mineral Prospectivity Prediction: A Case Study in Hongyuntan–Chilongfeng Mineral District,Xinjiang Province,China

Natural Resources Research - Continuous resource supply is one of the key points to improve comprehensive national strength. Resource prediction models supportive of target delineation for...     

Application of Artificial Neural Network for Gold–Silver Deposits Potential Mapping: A Case Study of Korea

The aim of this study is to analyze hydrothermal gold–silver mineral deposits potential in the Taebaeksan mineralized district, Korea, using an artificial neural network (ANN) and a geographic information system (GIS) environment. A spatial database considering 46 Au and Ag deposits, geophysical, geological, and geochemical data was constructed for the study area using the GIS. The geospatial factors were used with the ANN to analyze mineral potential. The Au and Ag mineral deposits were randomly divided into a training set (70%) to analyze mineral potential using ANN and a test set (30%) to validate predicted potential map. Four different training datasets determined from likelihood ratio and weight of evidence models were applied to analyze and validate the effect of training. Then, the mineral potential index (MPI) was calculated using the trained back-propagation weights, and mineral potential maps (MPMs) were constructed from GIS data for the four training cases. The MPMs were then validated by comparison with the test mineral occurrences. The validation results gave respective accuracies of 73.06, 73.52, 70.11, and 73.10% for the training cases. The comparison results of some training cases showed less sensitive to training data from likelihood ratio than weight of evidence. Overall, the training cases selected from 10% area with low and high index value of MPM_L and MPM_W gave higher accuracy (73.52 and 73.10%) for MPMs than those (73.06 and 70.11%, respectively) from known deposits and 10% area with low index value of MPI_L and MPI_W.     

Analysis of Spatial–Temporal Evolution of Mining-Induced Fracture Field: A Case Study Using Image Processing in the Shaqu Coal Mine,China

Natural Resources Research - Mining-induced fracture plays a key role in gas drainage for gas burst-prone underground coal mines, especially for closely multilayered coal seams. The layout and...     

Natural Gas Hydrates in the Offshore Beaufort–Mackenzie Basin—Study of a Feasible Energy Source II

In the offshore part of Beaufort–Mackenzie Basin depth of methane hydrate stability reaches more than 1.5 km. However, there are areas in the western part of the basin where there are no conditions of methane hydrate stability. Construction of the first contour maps displaying thickness of hydrate stability zones as well as hydrate stability zone thicknesses below permafrost in the offshore area, shows that these zones can reach 1200 m and 900 m, respectively. Depth to the base of ice-bearing relict permafrost under the sea (depth of the –1°C isotherm-ice-bearing permafrost base) and regional variations of geothermal gradient are the main controlling factors. Hydrostatic pressures in the upper 1500 m are the rule. History of methane hydrate stability zone is related mainly to the history of permafrost and it reached maximum depth in early Holocene. More recently, the permafrost and hydrate zone is diminishing because of sea transgression. Reevaluation of the location of possible gas hydrate occurrences is done from the analysis of well logs and other indicators in conjunction with knowledge of the hydrate stability zone. In the offshore Beaufort–Mackenzie Basin, methane hydrate occurs in 21 wells. Nine of these locations coincides with underlying conventional hydrocarbon occurrences. Previous analyses place some of the hydrate occurrences at greater depths than proposed for the methane hydrate-stability zone described in this study. Interpretation of geological cross sections and maps of geological sequences reveals that hydrates are occurring in the Iperk–Kugmallit sequence. Hydrate–gas contact zones, however, are possible in numerous situations. As there are no significant geological seals in the deeper part of the offshore basin (all hydrates are within Iperk), it is suggested that overlying permafrost and hydrate stability zone acted as the only trap for upward migrating gas during the last tens of thousand of years (i.e., Sangamonian to Holocene).     

Foreign-Area Expertise in U.S. Geography: An Assessment of Capacity based on Foreign-Area Dissertations, 1977–1991∗

Interpretations of a decline in foreign-area specialization have raised concerns about the capacity of geography in the United States to serve the expected increase in demands for foreign-area expertise. An assessment of foreign-area dissertations awarded by U.S. geography programs over a 15-year period (1977–1991) fails to support the concerns raised. No significant declines, if any at all, are found for early career interest and research in foreign areas. Several caveats are warranted, however. Geography has lost three doctoral programs with strong foreign-area dissertation records for the period in question. Also, non-U.S. citizens, many of whom do not remain in the United States after completion of their doctorate work, account for a significant proportion of foreign-area dissertations. Various questions that must be addressed to analyze the capacity question more broadly are identified.     

Residents’ Perception of the Recreational Value of Forest Parks: A Case Study in Shanghai,China

Forest parks provide important recreational and tourism bene?ts to residents, so it is essential to know what residents’ perceptions are regarding the recreational value of forest parks for participatory forest planning and management. This study investigated forest park recreational value in the physical, psychological, and social dimensions in Shanghai according to questionnaires completed by 658 respondents, and examined the relationships between recreational value and residents’ social variables by multiple correspondence analysis (MCA). The results show the following: 1) The recreational value of forest parks is perceived as most important in the psychological dimension, while in the social dimension it is appreciated the least. 2) In terms of the differences in forest park recreational value in suburbs and rural areas, the social value in rural areas had significantly higher scores than in the suburbs, and the psychological value in suburbs is much higher than that in the rural areas. 3) Regarding the social variables which characterize residents in suburbs and rural areas, females and younger groups tended to assign higher scores to recreational value than males and older groups. Moreover, citizens with low education or low income also assigned higher scores to recreational value compared to more educated or higher-income residents. The results of this study reveal the recreational value characteristics of Shanghai forest parks in the three dimensions, which can provide a scientific basis for the sustainable development of urban forest resources and contribute to reasonable planning and management.     

Spatial and Socioeconomic Effects of Social Housing Policies Implemented in Neoliberal Chile: The Case of Valparaíso

In this article, we examine the sociospatial effects of market-driven social housing policies implemented in neoliberal Chile. The study area encompasses the Valparaíso—Viña del Mar conurbation and its surrounding peri-urban and peripheral municipalities. To analyze the urban dynamic between 1990 and 2005 we use data showing the allocation of social housing complexes built during three time periods, socioeconomic data disaggregated at the district level, and semistructured interviews conducted with strategic actors from the public and private sectors. We conclude that private developers are increasingly building social housing complexes in peripheral municipalities, fragmenting the sociospatial landscape and concentrating poor families in ghetto-like compounds. We also encountered local governments (municipalities) with little capacity to mobilize the resources that they hold, and communities that remain disconnected from their local representatives.     

A Retrospective of Oil and Gas Field Development in the U.S. Outer Continental Shelf Gulf of Mexico, 1947–2017

Natural Resources Research - The U.S. Gulf of Mexico is a world-class hydrocarbon basin and industry has an impressive track record of advancing its capabilities in the region. From 1947 to 2017,...     

Land Reclamation in the Farming–Grazing Transitional Zone of Northeast China: 1644–1930

Using land reclamation information from gazetteers and corresponding historical records as further evidence, we extracted information about land reclamation in the early years of reclamation (at the “beginning date”) and during the climax period (the maximum extent). We analyzed land reclamation processes in the farming–grazing transitional zone in northeast China during the Qing Dynasty (1644–1911). Among thirty-seven counties for which the beginning date of land reclamation was recorded, 32 percent began reclamation early, primarily between the Shunzhi (1644–1661) and the Kangxi reigns (1662–1722), 19 percent were exploited during the Yongzheng reign (1723–1735), and 19 percent were exploited during the Guangxu reign (1875–1908). Among forty-six counties for which the maximum extent of land reclamation was recorded, the counties of Fengning, Longhua, and Longjiang were extensively exploited before 1800. From 1800 to 1860, four counties were extensively exploited, including Changtu County, Horqin Left Wing and Behind Banner, Horqin Left Wing and Middle Banner, and Shangyi County. Most counties were extensively exploited after 1860. Land reclamation was usually carried out by Han farmers, who were either recruited by Mongol landowners or were fleeing famine. Extensive land reclamation in the majority of counties was conducted during the Guangxu reign (1875–1908) in the late Qing Dynasty, when the Qing government implemented the policy of promoting Han migration to strengthen its hold on the frontier by distributing land.     

Empirical Relations Between Aquifer Geohydraulic–Geoelectric Properties Derived from Surficial Resistivity Measurements in Parts of Akwa Ibom State,Southern Nigeria

Natural Resources Research - Aquifer geohydraulic properties such as hydraulic conductivity and transmissivity are very vital parameters in groundwater resource management and exploitation. In this...     

Temperature variations evidenced by records on the latest spring snowing dates in Hangzhou of eastern China during 1131–1270AD

We collected and verified documentary records of the latest spring snowing dates(LSSD) in Hangzhou during Southern Song Dynasty. Furtherly, the statistical correlation between this proxy and February–April mean temperature in Hangzhou was examined, and samples later than the perennial mean of the LSSD during Southern Song Dynasty were transformed into the decadal mean of LSSD by means of Boltzmann function. General characteristics of this reconstructed LSSD series with a 10-year temporal resolution was analyzed, and it was also compared with other documentary evidences and reconstructed climate series in China for the period 1131–1270. The results and discussion suggested that:(1) Records of the LSSD in Hangzhou during Southern Song Dynasty did not refer to ice pellets and graupels, which had an explicit climate significance(–0.34℃/10 d, R2=0.37, p0.001). However, when this proxy is used to reconstruct temperature changes, all dates should be converted into proleptic Gregorian style and meet the same criterion of "true Qi" as the Chinese traditional calendar after 1929.(2) The decadal mean of LSSD can be effectively estimated by using the forefront of LSSD in the decade on the basis of Boltzmann function, whose extrapolation has a lesser uncertainty than those on the basis of linear models or polynomial models.(3) The spring climate in Hangzhou during 1131–1270 was almost as warm as the period 1951–1980. At the centennial scale, this period can be divided into two phases: the cold 1131–1170 and the warm 1171–1270. In the latter, 1181–1200 and 1221–1240 were two cold intervals at the multi-decadal scale.(4) The reconstructed LSSD series was consistent well with other documentary evidences and reconstructed climate series in China for 1131–1270, which may reflect the influence on the climate over most regions of China imposed by the Pacific Decadal Oscillation(PDO).