Areas Of High Productivity Research Articles

Understanding farmers’ eco-friendly fertilization technology adoption behavior using an integrated S-O-R model: The case of soil testing and formulated fertilization technology in shaanxi, china

The rapid development of high-standard farmland construction has triggered explosion of farmland cultivated land protection technologies in recent years. Contemporary, eco-friendly fertilization technology (EFFT) are rapidly becoming main force to achieve food security and promote the national ecological strategy. Hence, based on the extended stimulus-organism-response (S-O-R) theoretical analysis framework, this empirical research 295 field interview data of farmers in the high standard farmland grain main production area in Shaanxi Province, a developing country context, to analyze the mechanism of external incentives on farmers’ eco-friendly fertilization technology adoption behavior, further tested to examine the mediating effect of intrinsic perception and moderating effect of the family endowment. We applied the methodological approach, partial least square structural equation modeling (PLS-SEM), to test the hypothetical model. The results show that external incentives can effectively improve farmers’ technology adoptive behavior; internal perception has a significant positive effect on adoptive behavior, and it plays an intermediary role between external incentives and eco-friendly fertilization technology adoption behavior; family endowment has a significant positive effect on farmers’ technology adoption behavior, but the moderating effect of family endowment in external incentive-technology adoption behavior relationship is not significant. Therefore, we should choose appropriate and flexible government regulations, and give full play to the role of premium incentives, so as to improve the motivation of farmers to adopt eco-friendly fertilization technology.

Habitat amount or landscape configuration: Emerging HotSpot analysis reveals the importance of habitat amount for a grassland bird in South Dakota.

Habitat loss and fragmentation are two important drivers of biodiversity decline. Understanding how species respond to landscape composition and configuration in dynamic landscapes is of great importance for informing the conservation and management of grassland species. With limited conservation resources, prescribed management targeted at the appropriate landscape process is necessary for the effective management of species. We used pheasants (Phasianus colchicus) across South Dakota, USA as a model species to identify environmental factors driving spatiotemporal variation in population productivity. Using an emerging Hotspot analysis, we analyzed annual count data from 105 fixed pheasant brood routes over a 24-year period to identify high (HotSpot) and low (ColdSpot) pheasant population productivity areas. We then applied classification and regression tree modeling to evaluate landscape attributes associated with pheasant productivity among spatial scales (500 m and 1000 m). We found that the amount of grassland at a local spatial scale was the primary factor influencing an area being a HotSpot. Our results also demonstrated non-significant or weak effects of fragmentation per se on pheasant populations. These findings are in accordance with the habitat amount hypothesis highlighting the importance of habitat amount in the landscape for maintaining and increasing the pheasant population. We, therefore, recommend that managers should focus on increasing the total habitat area in the landscape and restoring degraded habitats. Our method of identifying areas of high productivity across the landscape can be applied to other species with count data.

Particle trajectories in an eastern boundary current using a regional ocean model at two horizontal resolutions

Lagrangian particle tracking (LPT) models are used to study the transport and dispersal of marine organisms. In LPT studies, the accuracy of the circulation is essential for nearshore habitats of Eastern Boundary Current (EBC) regions that are areas of high productivity and economically important fisheries. We used the California Current System as an example of an EBC region, specifically the Oregon coast located in the northern California Current System because it has distinct upwelling and downwelling regimes and variable shelf width. More specifically, we developed and applied a LPT model to compare and contrast particle drift patterns during the spring transition as it is an important period for spawning. We contrasted years (2016–18) using Regional Ocean Modeling System (ROMS) with different horizontal spatial resolutions (2 km, 250 m). Lagrangian particles experience stronger downward velocities and displacements to greater depths in the 250 m ROMS simulations that used a finer resolution bathymetry. Consequently, retention along the Oregon coast increases in the 250 m ROMS compared to the 2 km ROMS. After 10 days, 37%–83% of particles forced with the 2 km ROMS remain in the model domain, compared to 61%–86% of particles remaining when using the 250 m ROMS. Particles in the 250 m ROMS are advected to depth at specific times and locations for each simulated year, coinciding with the location and timing of a strong and shallow alongshore undercurrent that is not present in the 2 km ROMS. Additionally, ageostrophic dynamics close to shore, in the bottom boundary layer, and around headlands emerge in the 250 m resolution model, while they are at best poorly resolved in the 2 km resolution case. We conclude that the higher horizontal model resolution and bathymetry used in the 250 m ROMS generates well-resolved mesoscale and submesoscale features (e.g., surface, subsurface, and nearshore jet) that vary annually. These physical features are significantly different than those modeled by the 2 km model and may be responsible for these differences in particle dispersal. These results have implications for modeling the dispersal, growth, and development of coastal organisms with dispersing early life stages. • We compare ROMS of different horizontal resolutions in particle tracking models. • The higher resolution ROMS (250 m) better resolves mesoscale and submesoscale features. • The resolved mesoscale and submesoscale features may be due to higher resolution and bathymetry. • An increase in particle retention is linked to more resolved mesoscale features.

Ciliary flows in corals ventilate target areas of high photosynthetic oxygen production

Most tropical corals live in symbiosis with Symbiodiniaceae algae whose photosynthetic production of oxygen (O2) may lead to excess O2 in the diffusive boundary layer (DBL) above the coral surface. When flow is low, cilia-induced mixing of the coral DBL is vital to remove excess O2 and prevent oxidative stress that may lead to coral bleaching and mortality. Here, we combined particle image velocimetry using O2-sensitive nanoparticles (sensPIV) with chlorophyll (Chla)-sensitive hyperspectral imaging to visualize the microscale distribution and dynamics of ciliary flows and O2 in the coral DBL in relation to the distribution of Symbiodiniaceae Chla in the tissue of the reef building coral, Porites lutea. Curiously, we found an inverse relation between O2 in the DBL and Chla in the underlying tissue, with patches of high O2 in the DBL above low Chla in the underlying tissue surrounding the polyp mouth areas and pockets of low O2 concentrations in the DBL above high Chla in the coenosarc tissue connecting neighboring polyps. The spatial segregation of Chla and O2 is related to ciliary-induced flows, causing a lateral redistribution of O2 in the DBL. In a 2D transport-reaction model of the coral DBL, we show that the enhanced O2 transport allocates parts of the O2 surplus to areas containing less chla, which minimizes oxidative stress. Cilary flows thus confer a spatially complex mass transfer in the coral DBL, which may play an important role in mitigating oxidative stress and bleaching in corals.

The land use impacts of forestry and agricultural systems relative to natural vegetation; a fundamental energy dissipation approach

In agriculture and forestry the land use impacts that occur during production are important; including as necessary inputs for life cycle assessments. There are major differences in land use impacts between different forest management approaches and, in future, those forestry systems which deliver ecosystem services while having lower adverse land use impacts will be of greater value. Here we examine the land use impacts of seven contrasting forest management approaches and agricultural cropping systems at five locations in Europe. Comprehensive management data were used to calculate land use impacts in an evaluation system based on ecosystem thermodynamics. This approach has a number of advantages, including that it is suitable for input to life cycle assessment. This is the first time this approach has been used at a number of agricultural and forestry sites. We show that agriculture tends to have higher land use impacts than forestry. Those forestry systems that are more intensively managed in shorter rotations have larger land use impacts when calculated for the entire rotation, but this is not the case when land use impact is calculated on the basis of production unit. These findings support the use of landscape mosaics with some high production areas and will be of increasingly significance as we seek to achieve economic growth without environmental degradation. That managed forests have relatively low land use impacts has important implications for forestry restoration and climate mitigation programmes, including the forestry components of Nationally Determined Contributions under the UN Framework Convention on Climate Change.

High- and low-latitude forcing on the subarctic Pacific environment and productivity over the past 230 kyr

The subarctic Pacific Ocean, which is linked to both polar and tropical climates, is an area of high marine productivity and is sensitive to ocean-atmosphere CO2 flux. However, the mechanisms underlying the drivers of its productivity dynamics or patterns remain elusive. Using biogenic barium, opal, and terrigenous input in a sediment core for the past 230 kyr, we present a continuous high-resolution nutrient availability dynamic for the subarctic Pacific Ocean and assess possible changes to sea ice and glacial North Pacific Intermediate Water on nutrient upwelling in the region. We suggest that export production in this region is controlled by the freshwater discharge associated with moisture and heat from low-latitude and the iceberg discharge from Kamchatka glaciations under a weak Aleutian Low. These findings indicate that both high- and low-latitude climate systems forced the evolution of the marine environment and primary productivity in the high-latitude North Pacific.

Using stable isotopes analysis to understand ontogenetic trophic variations of the scalloped hammerhead shark at the Galapagos Marine Reserve.

Changes in life-history requirements drive trophic variations, particularly in large marine predators. The life history of many shark species is still poorly known and understanding their dietary ontogeny is a challenging task, especially for highly migratory species. Stable isotope analysis has proven as a useful method for examining the foraging strategies of sharks and other marine predators. We assessed the foraging strategies and ontogenetic changes of scalloped hammerhead sharks, Sphyrna lewini, at Galapagos Marine Reserve (GMR), by analysing δ13C and δ15N signatures in different maturity stages. Our isotopic results suggest ontogenetic shifts in resource use between sub-adult and adult stages, but not between adult and juvenile stages. Carbon isotopic signatures found in the juvenile stage were enriched in contrast to sub-adults (~0.73‰) suggesting a combination of the maternal input and the use of coastal resources around the Galapagos Islands. Adult female sharks also showed enrichment in δ13C (~0.53‰) in comparison to sub-adult stages that suggest feeding in high primary productivity areas, such as the GMR. This study improves the understanding of the trophic ecology and ontogenetic changes of a highly migratory shark that moves across the protected and unprotected waters of the Eastern Tropical Pacific.

Management practices should be strengthened in high potential vegetation productivity areas based on vegetation phenology assessment on the Qinghai-Tibet Plateau

Climate change and human activities have severely affected the structure and function of vegetation on the Qinghai-Tibet Plateau (QTP). Management practices have contributed to vegetation growth on the QTP, yet the response of vegetation productivity to management during the growing season remains unclear. Here, a fitted sixth-degree polynomial function was used to extract phenology-based vegetation productivity, which was quantified as the integrated normalized difference vegetation index (INDVI) over the length of the season during 2000–2019. Additionally, a new management practice intensity indicator was established to quantify the degree of ecological project and policy effectiveness on vegetation productivity. Three main results were obtained: (1) On a pixel-by-pixel basis, phenology-based vegetation productivity can avoid the impact of start-of-season (SOS) and end-of-season (EOS) variations. Vegetation productivity increased over 66% of the area of the QTP during 2000–2019, and the area with a significant increasing trend in vegetation productivity accounted for 9.15% of the QTP, including 5.65% in grassland and 0.23% in cultivated land. (2) Areas of increased vegetation productivity, grassland productivity, and cultivated land productivity affected by the positive impact from climate change accounted for 23.76%, 16.61%, and 0.31%, respectively, while they accounted for 41.29%, 28.10%, and 0.59% for human activities, respectively. (3) The regions of high-level management practice intensity accounted for 26.51% of the QTP but only 2.57% and 0.03% of grassland and cultivated land productivity, respectively. The regions of decreased grassland productivity still accounted for 21.85% of the QTP. Therefore, improving vegetation management practice intensity on grassland can increase regional vegetation productivity. These findings can provide effective guidance for regional vegetation management.

Novel Fish Predator Causes Sustained Changes in Its Prey Populations

Ecosystems are simultaneously regulated by bottom-up (resources) and top-down forces (predators). However, because predator-prey interactions operate on spatial scales beyond the reach of manipulative experimentation, the actual roles of predators remain poorly understood. In ecosystems where predators are naturally absent, biological invasions provide a unique experiment to shed light on the large-scale and long-term effects of predators in the recipient ecosystem. We combined data from long-term benthic monitoring, environmental conditions, and a census of round goby population to identify changes in the dominant benthic bivalve population (Mytilus trossulus and Macoma balthica) following round goby (Neogobius melanostomus) invasion. This study demonstrates a substantial change in the food web, with earlier primarily bottom-up regulated communities facing strong top-down control effects. The introduction of a novel predator to a species-poor ecosystem substantially reduced dominant invertebrate populations in a large part of the study area, sometimes with a time lag of 1−3 years. In general, the effects were less in high productivity areas. In some cases, community recovery was observed but rarely to pre-invasion levels, raising the question of the ability of bivalve communities to act as a natural filter. This study demonstrates long-term trends in benthic communities and by excluding possible effects due to the changing environment provides more evidence that invasive species transform coastal ecosystems over time and space.

Biogenic Methane Accumulation and Production in the Jurassic Low-Rank Coal, Southwestern Ordos Basin

Geological conditions are the key for coalbed methane (CBM) accumulation and production. However, the geological feature of CBM accumulation and production in the Jurassic of Ordos Basin lacks systematic and detailed evaluation, resulting in poor CBM production in this area. This study has determined the genetic types of gas according to geochemistry characteristics of the gas, the geological factors to control CBM accumulation and production performance were revealed, and a comprehensive method was established to evaluate favorable areas based on 32 sets of CBM well production data from Jurassic Yan’an Formation. The results show the coal macerals are rich in inertinite (41.13~91.12%), and the maximum reflectance of vitrinite (Ro,max) in coal is 0.56~0.65%. According to gas compositions and carbon isotopes analysis, the δ13C(CH4) is less than −55‰, and the content of heavy hydrocarbon is less than 0.05%. The value of C1/(C2 + C3) is 6800~98,000, that is, the CBM is a typical biogenic gas of low-rank coal. The CBM accumulation model is the secondary biogenic on the gentle slope of the basin margin, in which gas content is closely related to buried depth and hydrodynamic environment, i.e., the high gas content areas are mainly located in the groundwater weak runoff zone at the burial depth of 450 m~650 m, especially in the syncline. Meanwhile, gas production mainly depends on the location of the structure. The high gas production areas of vertical wells were distributed on the gentle slope with high gas content between anticline and syncline, and the horizontal wells with good performance were located near the core of the syncline. According to the above analysis combined with the random forest model, the study area was divided into different production favorable areas, which will provide a scientific basis for the CBM production wells.

Spatial\u2013temporal patterns and risk factors for human leptospirosis in Thailand, 2012\u20132018

Leptospirosis is a globally important zoonotic disease. The disease is particularly important in tropical and subtropical countries. Infections in humans can be caused by exposure to infected animals or contaminated soil or water, which are suitable for Leptospira. To explore the cluster area, the Global Moran’s I index was calculated for incidences per 100,000 population at the province level during 2012–2018, using the monthly and annual data. The high-risk and low-risk provinces were identified using the local indicators of spatial association (LISA). The risk factors for leptospirosis were evaluated using a generalized linear mixed model (GLMM) with zero-inflation. We also added spatial and temporal correlation terms to take into account the spatial and temporal structures. The Global Moran’s I index showed significant positive values. It did not demonstrate a random distribution throughout the period of study. The high-risk provinces were almost all in the lower north-east and south parts of Thailand. For yearly reported cases, the significant risk factors from the final best-fitted model were population density, elevation, and primary rice crop arable areas. Interestingly, our study showed that leptospirosis cases were associated with large areas of rice production but were less prevalent in areas of high rice productivity. For monthly reported cases, the model using temperature range was found to be a better fit than using percentage of flooded area. The significant risk factors from the model using temperature range were temporal correlation, average soil moisture, normalized difference vegetation index, and temperature range. Temperature range, which has strongly negative correlation to percentage of flooded area was a significant risk factor for monthly data. Flood exposure controls should be used to reduce the risk of leptospirosis infection. These results could be used to develop a leptospirosis warning system to support public health organizations in Thailand.

A Comprehensive Monitoring and Assessment System for Multiple Fisheries Resources in the Northwest Pacific Based on Satellite Remote Sensing Technology

Monitoring the dynamics of ocean-going fishing vessels is essential for fisheries stock assessment and management. In this paper, coupled fishery and remote sensing methods were applied to propose a satellite-based fishery resource monitoring and assessment system (SFRMAS) that supported chub mackerel (Scomber japonicus), Pacific saury (Cololabis saira) and neon flying squid (Ommastrephes bartramii) fishing activities in the northwest Pacific. A multispecies fishing vessel database was generated in the SFRMAS using visible infrared imaging radiometer suite day/night band (VIIRS/DNB) images, automatic identification system (AIS) data and multimarine remote sensing resources. The results showed that the VIIRS/DNB vessel detection (VVD) and AIS vessel detection approaches improved the extraction accuracy of multispecies fishing vessels. A high productivity area with a higher chlorophyll a concentration had the most concentrated distribution of mackerel vessels. The widest longitudinal migrations of the neon flying squid and the latitudinal ranges of Pacific saury were highly related to sea surface temperature (SST), which was well captured by the movement of the fishing vessels. In the SFRMAS, the accuracy of detected multispecies fishing days and fishing catches was mostly between 60 and 90%, which can provide data support for fisheries stock assessment and management.

Preliminary account on the bryozoans of the Alboran platform (Western Mediterranean), with description of two new species.

The Alboran platform, located in the Alboran Sea, is an area of high productivity due to the mixture of the Atlantic and Mediterranean waters, which produce an almost permanent upwelling in the region. It has been considered one of the main biodiversity hotspots in the Mediterranean Sea. Previous taxonomic studies on bryozoans carried out around the Alboran platform mentioned a total of 127 species collected at depths between 28 and 480 m. Here we report on four Indemares (Inventario y designacin de la Red Natura 2000 en reas marinas del Estado espaol) samples collected in 2011 and 2012 at depths between 95 and 120 m from a biogenic gravel bottom (i.e. small rocks and shells). Sixty-eight taxa belonging to 52 genera and 34 families were identified. Two species are proposed as new (Escharella similis n. sp. and Hemicyclopora admirabilis n. sp.), eight taxa were identified only to genus level although two of them (Chorizopora sp., Hippothoa sp.) are likely to be undescribed species, and one taxon only at family level. Among the species identified, 30 are new records for the Alboran platform, 13 are new records for the Alboran Sea, and Microporella funbio is recorded for the first time in the Mediterranean Sea. These results covered only a small part of the material sampled (4 out of 44 samples), which suggests that the number of bryozoan species in the Alboran platform is even higher, and also shows the importance of this area for bryodiversity.

Assessing alternatives for growth and yield modelling in eucalypt stands

Growth and yield estimates are extremely important for forest stand management. The application of simple models is often useful, as it allows the use of plots with few or a single measurement. The objective of this study was to evaluate methods for modelling eucalypt stand volume under different conditions of climate and soil. We fitted the Gompertz, Logistic and Exponential models, stratifying by project and for the entire data set, to model the dominant height and volume based on the usual validation statistics and residue analyses. To model growth and yield, five alternatives were evaluated: the Gompertz, Logistic and Exponential models, exponential-modified with the inclusion of the variable site index (SI) and the Clutter model. The best model was selected based on the validation statistics and the histogram of the relative error (RE). We conclude that the stratification by project presented greater accuracy of forecast. The best model to estimate yield was the exponential model modified with the inclusion of the variable SI. The technical age of cutting ranged from 36 months, in areas of higher productivity, to 84 months, in areas with low productivity.

Relationship between the chlorophyll a fluorescence and the yield in banana (Musa AAA Simmonds cv. Cavendish)

Chlorophyll fluorescence is used to characterize the plant response to natural environments or under stress conditions. This study aimed to identify correlations between the maximum quantum efficiency of PSII (Qy) with climatic and soil variables associated with bunch weight. The experimental design used in the field corresponds to an observational and longitudinal study, where 72 production units in the independent vegetative stage were randomly selected, of which 36 units from a low production area and 36 from a high production area. In each unit, the quantum yield (Qy: Fv/Fm) was measured and correlated with climatic and soil variables, the nutrient content in the leaves, and the average weight of the cluster in each sampled batches. The results indicated a correlation between Qy of -0.703 concerning temperature and -0.583 with radiation. On the other hand, pH and resistance to soil penetration are directly related to Qy to a lesser extent, with r2 values of 12.77 and 24.28%, respectively. Precipitation, wind, gusts, dew point, atmospheric pressure, and texture composition of the soil do not significantly affect Qy variation; when attacks of leaf pests (mites) occur, significant reductions are also observed in this. Qy is a variable that responds to the stress generated by factors external to the plant, these can significantly affect production, and which is reduced by up to two kg per cluster, with a bias of three to four weeks, when the loss of 0.04 points in the value of Qy occurs.

Ciliary Flows in Corals Ventilate Target Areas of High Photosynthetic Oxygen Production

Ciliary Flows in Corals Ventilate Target Areas of High Photosynthetic Oxygen Production

Spatiotemporal Variability of Aragonite Saturation State in the Northern East China Sea

AbstractIn order to evaluate the spatiotemporal distribution of the carbonate system in the northern East China Sea (ECS), we first measured the seasonal dissolved inorganic carbon (DIC) and total alkalinity (TA), from which the aragonite saturation state (Ωarag) was calculated for the years 2015–2017. The DIC, TA, and Ωarag were 1,680.9–2,211.4 μmol kg−1, 2,145.1–2,312.8 μmol kg−1, and 1.2–6.0, respectively. The spatiotemporal variability of Ωarag in the northern ECS was mainly controlled by seasonal water mass, such as Yellow Sea Surface Water, Changjiang Dilute Water, and Yellow Sea Bottom Water (YSBW). The lowest Ωarag (∼1.4) in bottom layer was observed in high primary production areas caused by the extension of the Changjiang River plume with the higher Ωarag (up to 6) and was closely linked to the YSBW with low Ωarag expanded southward from Yellow Sea near bottom. Although this area was not a hypoxia zone unlike western shelf region (Chinese region) of the northern ECS, YSBW near bottom could enhance the suppression of bottom aragonite without hypoxia. In eastern region of northern ECS, higher production at surface, YSBW with lower Ωarag extension, and longer respiration product accumulations near bottom tend to lower Ωarag, as compared with western region where the summer hypoxia led to lower Ωarag. Therefore, this result indicates that the eastern region of the northern ECS is also susceptible to ocean acidification, along with the summer hypoxic zone of the western region.

Performance of Large Seeded Faba Bean Genotypes for Yield and Related Agronomic Traits in Different Parts of Ethiopia

Faba bean (Vicia faba L.) is a high value crop in Ethiopia and has versatile uses. The national faba bean breeding program concentrates on the three major traits (grain yield, disease resistance and seed size) of the crop for varietal release for commercial production. Hence, ten faba bean genotypes were evaluated at Adet, Areka, Bekoji, Haramaya, Holetta and Jimma during the main cropping seasons of 2018 and 2019 using a randomized complete block design with four replications with the objectives to select the genotype with best performance in terms of important agronomic traits like grain yield, disease resistance, large seed size and other desirable agronomic traits for high potential production areas in Ethiopia. The combined analysis of variance across locations revealed that there is highly significant (P < 0.01) variation among the tested genotypes for grain yield, 1000-seeds weight, number of pods per plant, and days to 90% physiological maturity. The genotype EH011089-3 showed better performance than the tested genotypes having comparable grain yield performance (3803 kgha-1) with the two standard checks, Numan and Gora (3790 and 3897 kgha-1, respectively) while it had the highest 1000-seeds weight (1065 g) compared to the two standard checks, Numan and Gora (937 g and 786 g, respectively), i.e., 13.7% and 35.5% advantage, over the two standard checks, respectively. Additionally, EH011089-3 had better resistance for chocolate spot and rust diseases. Therefore, EH011089-3 was the best over the tested varieties and breeding lines. Genotype EH011089-3 is recommended for varietal release for commercial production all over in Ethiopia.

Impact of Freshwater Discharge on the Carbon Uptake Rate of Phytoplankton During Summer (January–February 2019) in Marian Cove, King George Island, Antarctica

Rapidly changing conditions in high-latitude coastal systems can significantly impact biogeochemical cycles because these systems are strongly influenced by freshwater discharged from melting glaciers and streams on land. Generally, Antarctic coastal areas are considered high-productivity areas in which phytoplankton growth prevails under various environmental conditions (e.g., oceanographic and meteorological conditions). This study provides carbon uptake rates of phytoplankton in Marian Cove during summer (January-February 2019). Daily depth-integrated carbon uptake varied greatly and averaged 0.8 g C m–2 day–1, with a maximum of 4.52 mg g C m–2 day–1 recorded on 14 January. Similarly, the observed biomass standing stocks were very high (up to 19.5 mg m–3 chlorophyll a) and were dominated by microphytoplankton (20–200 μm), representing 84% of total chlorophyll a (chl-a). The depth-integrated chl-a and carbon uptake decreased from outer to inner areas (close to the glacial front) in the cove. As the austral summer progressed, the freshening of the surface waters coincided with high water stability and suspended material and with low productivity when nanophytoplankton were present (2–20 μm; >60%). These findings suggest that both photosynthetically active radiation penetrating the water column and enhanced turbidity control light availability for phytoplankton, as well as their community compositions.

Review of the Hydrogeological Controls on Coalbed Methane (CBM) and Development Trends

Hydrogeological conditions can control the generation, preservation, enrichment, and production of coalbed methane (CBM) in the field; however, research on these impacts is insufficient, resulting in the limitation of the development of coalbed methane. This paper summarizes the current research status and development trends of the effect of hydrogeology on CBM using methods such as mathematical statistics, literature analysis, well logging, and hydrochemical analysis. The results indicate that it is beneficial for the generation of secondary biogenic gases in low-rank coal seams under the situations like active hydrodynamic conditions with a salinity less than 1000 mg/L, a pH range from 5.9 to 8.8, or a range of oxidation-reduction potential from -540 mV to -590 mV. The abnormally high temperature due to the magmatic-hydrothermal fluids accelerates the metamorphism of coal rocks, leading to the promotion of the generation of thermogenic gases. When the coalbed structural conditions of one area are similar to the depositional conditions in that area, the CBM is accumulated if the conditions of that area meet the following criteria: the water type is NaHCO3, the salinity is greater than 1500 mg/L, the desulfurization coefficient is less than 1, and the sodium-chloride coefficient is less than 10. The stable isotope analysis of CBM well-produced water shows that the δD values in the groundwater shift to the left of the global meteoric water line, indicating that the produced water comes from atmospheric precipitation. In the CBM enrichment zone, the area with a relatively high salinity and a low sodium-chloride coefficient is the high-production area. Based on our study, three high CBM-production patterns are summarized: coalbed structure-hydraulic trapping, fold limb-fracture development, and syncline core-water stagnation. Additionally, four development trends of the control of hydrogeology on CBM are proposed: transformation from qualitative evaluation to quantitative evaluation, from a singular evaluation standard to multiple evaluation standards, from static evaluation to dynamic evaluation, and from pure theoretical research to theoretical guidance on production practices.