Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation (K2qn^1) and Member 1 and 2 of the Nenjiang Formation (K2n^1-2) of Late Cretaceous age in the Songliao Basin reveals...Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation (K2qn^1) and Member 1 and 2 of the Nenjiang Formation (K2n^1-2) of Late Cretaceous age in the Songliao Basin reveals sedimentary cyclicities controlled by Milankovitch climate periodicities. The recognition of Milankovitch cycles allows estimation of an average accumulation rate of ~7.55- 8.62 cm/ka for the K2qn^1 sections, and ~6.69-10.16 cm/ka for the K2n^1-2 sections. Two marine transgression events occurred during the deposition of K2qn^1 and K2n^1-2 and their ages are at ~0.74- 1.10 Ma and ~2.38-4.84 Ma, respectively. Identification of Milankoviteh cycles from fine-grained deep lake sedimentary rocks in the Songliao Basin may provide great potential for high-resolution stratigraphic subdivisions and correlations.展开更多
The increase in forest-wildfire events around the world has revived the old debate regarding the practice of salvage logging and its effectiveness in comparison to the unlogged, natural regeneration of burned forests....The increase in forest-wildfire events around the world has revived the old debate regarding the practice of salvage logging and its effectiveness in comparison to the unlogged, natural regeneration of burned forests. Since the logging of burned trees may have undesirable outcomes in soil systems, such as soil compaction and nutrient losses, these changes could further cause disturbances to soil microbial-community activity. The aim of this study was to examine chemical and biological changes in soil under two post-fire practices: salvage logging and unlogged, natural regeneration of burned areas, in the recently burned Byria Forest in Israel. Results indicated that salvage logging had a short- lived effect on soil chemical and biological properties that was confined mostly to the first year after logging. Soil moisture was greatly affected by salvage logging, and drier conditions were found in the logged compared to the unlogged burned areas. Moreover, logging had a negative effect on microbial biomass, with reduced biomass in the logged compared to unlogged areas, which was more evident during the first year after fire. These findings support the recommendations in the literature to postpone post-fire practices such as logging or, in turn, to combine the two practices in order to create a mosaic of burned-logged and burned-naturally regenerated areas.展开更多
Subri River Forest Reserve(SR)is the most extensive forest area in Ghana with an accompanying rich floral species.Over the years,logging from both legally prescribed and illegal operations remain the predominant fores...Subri River Forest Reserve(SR)is the most extensive forest area in Ghana with an accompanying rich floral species.Over the years,logging from both legally prescribed and illegal operations remain the predominant forest disturbance in SR.Gap creation following logging is crucial in determining tree species composition and diversity.Hence,the study evaluated the composition and diversity of naturally regenerated tree species in logging gaps of different sizes and,again examined the roles of these tree species in fulfilling the economic and ecological agenda of sustainable forest management after logging in SR.Twelve gaps were randomly selected:4 each were grouped into small size(≤200 m^(2)),medium size(201–300 m^(2)),and large size(≥300 m^(2)).Data were gathered from 1 m^(2) circular area at gap centres and repeatedly inside 1 m width strip along 20 m individual N-S-E-W transects.Species diversity differed significantly between gap sizes.Higher diversity indices were measured in large size gaps.Gap sizes shared similar species.There were significant differences among various height groupings of tree species across all three gap sizes.Pioneers preferred medium to large size gaps,while shadetolerant tree species preferred small size gaps for their abundance.Vulnerable and Lower Risk Near Threatened tree species under Conservation Status and,Premium and Commercial tree species under Utilisation Status preferred small size gaps for their proliferation and conservation.Therefore,we recommend the single tree-based selective logging for ensuring creations of small to medium size(200–300 m^(2))gaps through adjustments to the logging permit process,revision of Allocation Quota Permit,strict adherence to the 40-year polycyclic selection system,along with more dedicated enforcement and monitoring.Changes along these protocols would tremendously facilitate natural regeneration of different suites of timber species resulting in the improvement of the overall biodiversity conservation associated with the forest,more sustainable forest harvests and more income to those who receive permits.展开更多
The activity concentrations of naturally occurring 238U, 232Th and 40K in surface soils along Qarun Lake and Wadi El Rayan located in Faiyum, Egypt were determined. The measurements were carried out through gamma-ray ...The activity concentrations of naturally occurring 238U, 232Th and 40K in surface soils along Qarun Lake and Wadi El Rayan located in Faiyum, Egypt were determined. The measurements were carried out through gamma-ray spectrometry using a coaxial HPGe detector. The results were compared with those reported in the literature. The radiological hazard radium-equivalent activity index, external and internal indices, radioactivity level index, absorbed dose rate, annual effective dose rate and total absorbed dose rate associated with radioactivity in all samples were evaluated and compared with recommended values. Correlation studies between pairs of radionuclides were performed and discussed.展开更多
The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in...The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m<sup>2</sup> and 1742 seedlings/m<sup>2</sup>. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m<sup>2</sup> and 4 seedlings/m<sup>2</sup>, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.展开更多
We investigated the quantity and quality of fallen logs in different Tsuga longibracteata forest communities in the Tianbaoyan National Nature Reserve. We used redundancy analysis to determine the spatial distribution...We investigated the quantity and quality of fallen logs in different Tsuga longibracteata forest communities in the Tianbaoyan National Nature Reserve. We used redundancy analysis to determine the spatial distribution of fallen logs in the different forest communities and to analyze the relationships among stand structure, topographic factors and human disturbance. The volume, covered area, mean log length and number of fallen logs differed significantly among forest types(P < 0.05), but mean diameter at breast height showed no significant difference(P > 0.05). The log volume and covered area in different forest types showed the following trend: T. longibracteata pure forest < T.longibracteata + Oligostachyum scabriflorur < T.longibracteata + hardwood < Rhododendron simiarum + T. longibracteata < T. longibracteata +Phyllostachys heterocycla pubescens. The spatial distribution patterns of logs quantity and quality indicated that log volume and covered area were strongly affected by environmental factors in the following order: human disturbance > elevation >slope position > bole height > tree height > slope aspect > density > basal area > slope gradient. The relative contribution of environmental variables on the total variance was topography(76%) >disturbance(42%) > stand structure(35%).Topography and disturbance combined explained83% of the variance. Fallen logs quantity and qualitywere negatively related to elevation and slope position,and positively associated to human disturbance. The log volume decreased from northern to southern slopes. Environmental factors had the highest impact on class I(slightly decayed), and lowest impact on class V(highly decayed).展开更多
A method is proposed to characterize the fast neutron scattering cross-section ( s f) quantitatively by the combina-tion of inelastic gamma rays and captured gamma rays, so as to realize the gas saturation evaluation ...A method is proposed to characterize the fast neutron scattering cross-section ( s f) quantitatively by the combina-tion of inelastic gamma rays and captured gamma rays, so as to realize the gas saturation evaluation of CO_(2)-injected heavy oilreservoirs based on the three-de tector pulsed neutron logging technology. Factors influencing of the evaluation effect of thismethod are analyzed and the effectiveness of this method is verified by a simulation example. By using the Monte Carlo simu-lation method and the physical model of bulk-volume rock, the relationship between s f and CO_(2) saturation is studied, and thesaturation interpretation model is established. The influences of formation temperature and pressure, heavy oil density, bore-hole fluid and reservoir methane content on the evaluation results of CO_(2) saturation are analyzed. The results show that thecharacterization of s f by the combination of secondary gamma information can eliminate the influence of formation lithology,borehole fluid and methane content are the main factors affecting the quantitative monitoring of CO_(2) saturation, and the ef-fects of formation temperature and pressure and heavy oil density are negligible. The simulation example verified the feasibilityof the method for evaluating the CO_(2) saturation of CO_(2)-injected heavy oil reservoirs.展开更多
<p> The concentrations and distribution of naturally occurring radionuclides <span><span><span><span>(</span><sup><span>238</span></sup><span>U, </s...<p> The concentrations and distribution of naturally occurring radionuclides <span><span><span><span>(</span><sup><span>238</span></sup><span>U, </span><sup><span>235</span></sup><span>U, </span><sup><span>234</span></sup><span>U, </span><sup><span>230</span></sup><span>Th, </span><sup><span>226</span></sup><span>Ra, </span><sup><span>210</span></sup><span>Pb, </span><sup><span>232</span></sup><span>Th, </span><sup><span>228</span></sup><span>Ra, and </span><sup><span>40</span></sup><span>K)</span></span></span></span><span><span><span><span> were determined by alpha and gamma spectrometry in soil and sediments collected from Luilu and Dilala rivers located in the mining district of Kolwezi (Lualaba Province) of the Democratic Republic of the Congo. The average concentrations of </span><sup><span>238</span></sup><span>U and </span><sup><span>226</span></sup><span>Ra in the analyzed samples were 5</span></span></span></span><span><span><span> </span></span></span><span><span><span>-</span></span></span><span><span><span> </span></span></span><span><span><span>10 times higher than the world average values for soil provided by the </span></span></span><span><span><span>United Nations Scientific Committee on the Effects of Atomic Radiation. However,</span></span></span><span><span><span><span> the average concentrations of </span><sup><span>232</span></sup><span>Th were found similar to the world average. In both river basins, artisanal mining activities and</span></span></span></span><span><span><span> mineral washing sites displayed the higher concentration values of radionuclides. The mean values of health risk indices calculated for those sites were found sig</span></span></span><span><span><span>nificantly higher compared to world average levels. Radiation protection measures seem needed to ensure the radiation safety of local populations.</span></span></span> </p> <p> <span><span><span><br /> </span></span></span> </p> <p> <span style="font-size:16px;"><strong>Graphical Abstract</strong></span> </p> <p> <span><span><span><img src="Edit_7a1bf87c-f0a0-4c34-80b2-7e488ac5e4a2.png" alt="" /><br /> </span></span></span> </p>展开更多
In order to reveal the photosynthetic characteristics of C. trichotomum responses to drought, salt and water-logging stresses, one-year-old potted seedlings were taken as materials, and the several stresses including ...In order to reveal the photosynthetic characteristics of C. trichotomum responses to drought, salt and water-logging stresses, one-year-old potted seedlings were taken as materials, and the several stresses including natural drought, submergence stress, water-logging and different salt treatments (0.2%, 0.4%, 0.6% and 0.8% NaCl) were carried out on August 15, 2012. The morphological and photosynthetic characteristics were observed and determined. The results showed that adverse enviromental stress had a significant effect on the morphological changes and photosynthetic characteristics of C. trichotomum. On the 14th day after natural drought, the leaves wilted and could not recovery at night, and 60% of the seedlings could recover after re-watering. From the 7th day to the 10th day after submergence stress treatment, the 2nd and the 3rd leaves at the base of 60% seedling turned yellow and the lenticels were observed. At the early stage of water-logging stress, white lenticels appeared at the base of seedlings, and the leaves wilted, chlorina and fallen off on the 8th day. A large number of leaves fallen off under 0.6% NaCl or more salt stress, and even the whole plant died. The chlorophyll content, net photosynthetic rate (Pn) and transpiration rate (Tr) decreased gradually with the stress process, such as 8 days after natural drought, less than 0.4% salt stress and water-logging stress, but the changes were not significant compared with those of the control. With the increase of the stress intensity and the prolonged time, the changes of photosynthetic index were significant. All the results indicated that C. trichotomum had a certain degree of tolerance to drought, water and salt, but it was not suitable for living, in water-logging condition for a long time.展开更多
Fifteen Porcelain and Ceramic Dinner Wares samples (collected from local commercial suppliers—Jeddah Saudi Arabia) were studied applying X-Ray Diffraction and Atomic Absorption techniques were used to study the Chemi...Fifteen Porcelain and Ceramic Dinner Wares samples (collected from local commercial suppliers—Jeddah Saudi Arabia) were studied applying X-Ray Diffraction and Atomic Absorption techniques were used to study the Chemical, Mineral, Compositions Concentrations (of Some Metals). In addition, the Natural Radioactivity measurements of <sup>226</sup>Ra, <sup>232</sup>Th and <sup>40</sup>K, was used by a high-purity germanium (HPGe) detector. X-ray diffraction results showed that the major mineral constituents of 15 samples were quartz (SiO<sub>2</sub>) (except one), minor and trace elements vary from sample to sample. Atomic absorption spectroscopy results of the concentrations for (Al, Pb, Bi, U, Th and K) in (ppm) showed that Al<sub>2</sub>O average was 10.3 (ppm) (10%) less than the acceptable value. PbO, its average was 1.65 ppm which was slightly greater than the allowed value 1.35 ppm. Bi concentrations for all samples were lower than (DL < 10). For most samples U, concentrations were lower than (DL < 5) except samples C9 and C11. Th concentrations ranged from LDL (<1 to 52.88) and were much greater than the acceptable value 7.24 ppm except samples P1, P2, P4. The potassium concentration average was greater than the acceptable value. The average concentrations of <sup>238</sup>U, <sup>232</sup>Th and <sup>40</sup> K were (83.83, 91.05 and 751.07) Bq/kg dry. The radium equivalent activity concentration <em>Ra</em><sub><em>eq</em></sub> (Bq/kg) (302.61) was less than recommended value (370), gamma dose rate <em>D</em> (nGy/h) average (140.15) was much higher than the recommended value (60) (UNSCEER). <em>D</em><sub><em>eff</em></sub> (mSv/year) and <em>H</em><sub><em>ix</em></sub> were below the published admissible limit ≤ 1 and the risk is negligible. This study offers needed information for consumers at exposure risk and is useful to be found in terms of radiation protection.展开更多
Natural radioactivity is a source of continuous exposure to human beings. The natural radioactivity due to the presence of 226Ra, 232Th and 40K in sand samples collected from Ad-Dahna was measured by means of HPGe. Th...Natural radioactivity is a source of continuous exposure to human beings. The natural radioactivity due to the presence of 226Ra, 232Th and 40K in sand samples collected from Ad-Dahna was measured by means of HPGe. The measured activity concentrations of radionuclides were compared with the worldwide reported data. Mean measured activity concentrations of 226Ra, 232Th and 40K varied between 16.2 - 30.6, 15.8 - 36.7 and 285.3 - 533.2 Bq·kg–1 respectively with a mean value of 23.4 ± 4.3 Bq·kg–1, 29.7 ± 5.9 Bq·kg–1 and 380 ± 65 Bq·kg–1 respectively. Mean values of radium equivalent activity, absorbed dose rate and external radiation hazard index were 106 ± 8 Bq·kg–1, 51.4 nGy·h–1 and 0.29 respectively. The annual effective radiation dose was calculated to be 0.32 mSv·y–1. The Raeq values of sand samples are lower than the limit of 370 Bq·kg–1, equivalent to a gamma dose of 1.5 mSv·yr–1.This study shows that the measured sand samples do not pose any significant source of radiation hazard and are safe for use in building materials.展开更多
In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the ...In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) for thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The mean values of the activity concentrations of U-238 (Ra-226), Th-232, K-40 and Cs-137 in the igneous samples are found as (11.0, 11.50, 1172.71, 1.47) Bq/Kg respectively. In the sedimentary rocks, the mean values of the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) equal to (12.04, 13.18, 1131.36, 1.60) Bq/Kg respectively. The averages of radiological hazards (<em>Ra</em><sub><em>eq</em></sub>, <em>H</em><sub><em>ex</em></sub> and <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">γ</span></span></em></sub>) were calculated and found to be within the UNSCEAR permissible limit values (370 Bq/kg for <em>Ra</em><sub><em>eq</em></sub>, and 1 for <em>H</em><sub><em>ex</em></sub> and <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">γ</span></span></em></sub>), except for a slight increase of average value of <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">γ</span></span></em></sub> in the igneous rock samples (1.36). The results indicate that the dose rate values depend on the kind of rocks (high in some igneous rock samples, and most of sedimentary rock samples have low dose rate). The activities of naturalnuclides were predicted and simulated in T time using a written MATLAB R2020a script based on the average activity concentrations and respective half-lives of U-238 and Th-232 series, and K-40, this is to evaluate the future effects of natural radionuclides on the population and estimate the human inputs in the future.展开更多
The unconformity surface at the bottom of the Paleogene is one of the most important migration pathways in the Sikeshu Sag of the Junggar Basin,which consists of three layers:upper coarse clastic rock,lower weatherin...The unconformity surface at the bottom of the Paleogene is one of the most important migration pathways in the Sikeshu Sag of the Junggar Basin,which consists of three layers:upper coarse clastic rock,lower weathering crust and leached zone.The upper coarse clastic rock is characterized by higher density and lower SDT and gamma-ray logging parameters,while the lower weathering crust displays opposite features.The transport coefficient of the unconformity surface is controlled by its position in respect to the basal sandstone; it is higher in the ramp region but lower in the adjacent uplifted and sag areas.The content of saturated hydrocarbons increases with the decrease of the content of nonhydrocarbons and asphaltenes.The content of benzo[c] carbazole decreases as the content of benzo[a]carbazole and [alkyl carbazole]/[alkyl + benzo carbazole] increases.This suggests that the unconformity surface is an efficient medium for the transportation of hydrocarbons.展开更多
Spectrum analysis of natural gamma ray spectral logging (SGR) data is a critical part of surface informa- tion processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-...Spectrum analysis of natural gamma ray spectral logging (SGR) data is a critical part of surface informa- tion processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-to-noise ratio problem of logging measurements, SGR is usually treated with a low confidence level. The Direct Demodulation (DD) method is an advanced technique to solve modulation equations interactively under physical constraints. It has higher sensitivity and spatial resolution than the traditional methods and can effectively suppress the logging noise. Based on standard count rate spectral data obtained from the China Offshore Oil Logging Company SGR Calibration Facility, this paper presents the application of the DD method to gamma-ray logging. The results are compared with four traditional algorithmic methods, showing that the DD method is a credible choice, with higher sensitivity and higher spatial resolution in gamma-ray log interpretation. The Point-Spread-Function of the Shengli Oil Logging Company's natural gamma ray spectroscopy instrument is obtained for the first time. The quantities of various radionuclides in their calibration pits are also obtained. The DD method was applied successfully to gamma-ray logging, offering a new option for SGR logging algorithm selection.展开更多
文摘Spectrogram analysis of seven natural gamma-ray logging of Member 1 of the Qingshankou Formation (K2qn^1) and Member 1 and 2 of the Nenjiang Formation (K2n^1-2) of Late Cretaceous age in the Songliao Basin reveals sedimentary cyclicities controlled by Milankovitch climate periodicities. The recognition of Milankovitch cycles allows estimation of an average accumulation rate of ~7.55- 8.62 cm/ka for the K2qn^1 sections, and ~6.69-10.16 cm/ka for the K2n^1-2 sections. Two marine transgression events occurred during the deposition of K2qn^1 and K2n^1-2 and their ages are at ~0.74- 1.10 Ma and ~2.38-4.84 Ma, respectively. Identification of Milankoviteh cycles from fine-grained deep lake sedimentary rocks in the Songliao Basin may provide great potential for high-resolution stratigraphic subdivisions and correlations.
文摘The increase in forest-wildfire events around the world has revived the old debate regarding the practice of salvage logging and its effectiveness in comparison to the unlogged, natural regeneration of burned forests. Since the logging of burned trees may have undesirable outcomes in soil systems, such as soil compaction and nutrient losses, these changes could further cause disturbances to soil microbial-community activity. The aim of this study was to examine chemical and biological changes in soil under two post-fire practices: salvage logging and unlogged, natural regeneration of burned areas, in the recently burned Byria Forest in Israel. Results indicated that salvage logging had a short- lived effect on soil chemical and biological properties that was confined mostly to the first year after logging. Soil moisture was greatly affected by salvage logging, and drier conditions were found in the logged compared to the unlogged burned areas. Moreover, logging had a negative effect on microbial biomass, with reduced biomass in the logged compared to unlogged areas, which was more evident during the first year after fire. These findings support the recommendations in the literature to postpone post-fire practices such as logging or, in turn, to combine the two practices in order to create a mosaic of burned-logged and burned-naturally regenerated areas.
基金funded by the Internal Grant Agency of Mendel University in Brno(LDF_VP_2019015)the Framework of Bilateral Mobility Program for Traineeship of Doctoral Students,MENDELU。
文摘Subri River Forest Reserve(SR)is the most extensive forest area in Ghana with an accompanying rich floral species.Over the years,logging from both legally prescribed and illegal operations remain the predominant forest disturbance in SR.Gap creation following logging is crucial in determining tree species composition and diversity.Hence,the study evaluated the composition and diversity of naturally regenerated tree species in logging gaps of different sizes and,again examined the roles of these tree species in fulfilling the economic and ecological agenda of sustainable forest management after logging in SR.Twelve gaps were randomly selected:4 each were grouped into small size(≤200 m^(2)),medium size(201–300 m^(2)),and large size(≥300 m^(2)).Data were gathered from 1 m^(2) circular area at gap centres and repeatedly inside 1 m width strip along 20 m individual N-S-E-W transects.Species diversity differed significantly between gap sizes.Higher diversity indices were measured in large size gaps.Gap sizes shared similar species.There were significant differences among various height groupings of tree species across all three gap sizes.Pioneers preferred medium to large size gaps,while shadetolerant tree species preferred small size gaps for their abundance.Vulnerable and Lower Risk Near Threatened tree species under Conservation Status and,Premium and Commercial tree species under Utilisation Status preferred small size gaps for their proliferation and conservation.Therefore,we recommend the single tree-based selective logging for ensuring creations of small to medium size(200–300 m^(2))gaps through adjustments to the logging permit process,revision of Allocation Quota Permit,strict adherence to the 40-year polycyclic selection system,along with more dedicated enforcement and monitoring.Changes along these protocols would tremendously facilitate natural regeneration of different suites of timber species resulting in the improvement of the overall biodiversity conservation associated with the forest,more sustainable forest harvests and more income to those who receive permits.
文摘The activity concentrations of naturally occurring 238U, 232Th and 40K in surface soils along Qarun Lake and Wadi El Rayan located in Faiyum, Egypt were determined. The measurements were carried out through gamma-ray spectrometry using a coaxial HPGe detector. The results were compared with those reported in the literature. The radiological hazard radium-equivalent activity index, external and internal indices, radioactivity level index, absorbed dose rate, annual effective dose rate and total absorbed dose rate associated with radioactivity in all samples were evaluated and compared with recommended values. Correlation studies between pairs of radionuclides were performed and discussed.
文摘The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m<sup>2</sup> and 1742 seedlings/m<sup>2</sup>. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m<sup>2</sup> and 4 seedlings/m<sup>2</sup>, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.
基金supported by the National Natural Science Foundation of China (Grant No.31370624)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20103515110005)the Natural Science Foundation of Fujian, China (Grant No. 2011J01071)
文摘We investigated the quantity and quality of fallen logs in different Tsuga longibracteata forest communities in the Tianbaoyan National Nature Reserve. We used redundancy analysis to determine the spatial distribution of fallen logs in the different forest communities and to analyze the relationships among stand structure, topographic factors and human disturbance. The volume, covered area, mean log length and number of fallen logs differed significantly among forest types(P < 0.05), but mean diameter at breast height showed no significant difference(P > 0.05). The log volume and covered area in different forest types showed the following trend: T. longibracteata pure forest < T.longibracteata + Oligostachyum scabriflorur < T.longibracteata + hardwood < Rhododendron simiarum + T. longibracteata < T. longibracteata +Phyllostachys heterocycla pubescens. The spatial distribution patterns of logs quantity and quality indicated that log volume and covered area were strongly affected by environmental factors in the following order: human disturbance > elevation >slope position > bole height > tree height > slope aspect > density > basal area > slope gradient. The relative contribution of environmental variables on the total variance was topography(76%) >disturbance(42%) > stand structure(35%).Topography and disturbance combined explained83% of the variance. Fallen logs quantity and qualitywere negatively related to elevation and slope position,and positively associated to human disturbance. The log volume decreased from northern to southern slopes. Environmental factors had the highest impact on class I(slightly decayed), and lowest impact on class V(highly decayed).
基金Supported by the National Natural Science Foundation of China(41974127,41974155)China University of Petroleum(East China)Graduate Student Innovation Project Funding Project(YCX2020008)。
文摘A method is proposed to characterize the fast neutron scattering cross-section ( s f) quantitatively by the combina-tion of inelastic gamma rays and captured gamma rays, so as to realize the gas saturation evaluation of CO_(2)-injected heavy oilreservoirs based on the three-de tector pulsed neutron logging technology. Factors influencing of the evaluation effect of thismethod are analyzed and the effectiveness of this method is verified by a simulation example. By using the Monte Carlo simu-lation method and the physical model of bulk-volume rock, the relationship between s f and CO_(2) saturation is studied, and thesaturation interpretation model is established. The influences of formation temperature and pressure, heavy oil density, bore-hole fluid and reservoir methane content on the evaluation results of CO_(2) saturation are analyzed. The results show that thecharacterization of s f by the combination of secondary gamma information can eliminate the influence of formation lithology,borehole fluid and methane content are the main factors affecting the quantitative monitoring of CO_(2) saturation, and the ef-fects of formation temperature and pressure and heavy oil density are negligible. The simulation example verified the feasibilityof the method for evaluating the CO_(2) saturation of CO_(2)-injected heavy oil reservoirs.
文摘<p> The concentrations and distribution of naturally occurring radionuclides <span><span><span><span>(</span><sup><span>238</span></sup><span>U, </span><sup><span>235</span></sup><span>U, </span><sup><span>234</span></sup><span>U, </span><sup><span>230</span></sup><span>Th, </span><sup><span>226</span></sup><span>Ra, </span><sup><span>210</span></sup><span>Pb, </span><sup><span>232</span></sup><span>Th, </span><sup><span>228</span></sup><span>Ra, and </span><sup><span>40</span></sup><span>K)</span></span></span></span><span><span><span><span> were determined by alpha and gamma spectrometry in soil and sediments collected from Luilu and Dilala rivers located in the mining district of Kolwezi (Lualaba Province) of the Democratic Republic of the Congo. The average concentrations of </span><sup><span>238</span></sup><span>U and </span><sup><span>226</span></sup><span>Ra in the analyzed samples were 5</span></span></span></span><span><span><span> </span></span></span><span><span><span>-</span></span></span><span><span><span> </span></span></span><span><span><span>10 times higher than the world average values for soil provided by the </span></span></span><span><span><span>United Nations Scientific Committee on the Effects of Atomic Radiation. However,</span></span></span><span><span><span><span> the average concentrations of </span><sup><span>232</span></sup><span>Th were found similar to the world average. In both river basins, artisanal mining activities and</span></span></span></span><span><span><span> mineral washing sites displayed the higher concentration values of radionuclides. The mean values of health risk indices calculated for those sites were found sig</span></span></span><span><span><span>nificantly higher compared to world average levels. Radiation protection measures seem needed to ensure the radiation safety of local populations.</span></span></span> </p> <p> <span><span><span><br /> </span></span></span> </p> <p> <span style="font-size:16px;"><strong>Graphical Abstract</strong></span> </p> <p> <span><span><span><img src="Edit_7a1bf87c-f0a0-4c34-80b2-7e488ac5e4a2.png" alt="" /><br /> </span></span></span> </p>
基金Supported by the Major Scientific Research Projects of the 12th Five-year National Public welfare Industry(201104002-6)
文摘In order to reveal the photosynthetic characteristics of C. trichotomum responses to drought, salt and water-logging stresses, one-year-old potted seedlings were taken as materials, and the several stresses including natural drought, submergence stress, water-logging and different salt treatments (0.2%, 0.4%, 0.6% and 0.8% NaCl) were carried out on August 15, 2012. The morphological and photosynthetic characteristics were observed and determined. The results showed that adverse enviromental stress had a significant effect on the morphological changes and photosynthetic characteristics of C. trichotomum. On the 14th day after natural drought, the leaves wilted and could not recovery at night, and 60% of the seedlings could recover after re-watering. From the 7th day to the 10th day after submergence stress treatment, the 2nd and the 3rd leaves at the base of 60% seedling turned yellow and the lenticels were observed. At the early stage of water-logging stress, white lenticels appeared at the base of seedlings, and the leaves wilted, chlorina and fallen off on the 8th day. A large number of leaves fallen off under 0.6% NaCl or more salt stress, and even the whole plant died. The chlorophyll content, net photosynthetic rate (Pn) and transpiration rate (Tr) decreased gradually with the stress process, such as 8 days after natural drought, less than 0.4% salt stress and water-logging stress, but the changes were not significant compared with those of the control. With the increase of the stress intensity and the prolonged time, the changes of photosynthetic index were significant. All the results indicated that C. trichotomum had a certain degree of tolerance to drought, water and salt, but it was not suitable for living, in water-logging condition for a long time.
文摘Fifteen Porcelain and Ceramic Dinner Wares samples (collected from local commercial suppliers—Jeddah Saudi Arabia) were studied applying X-Ray Diffraction and Atomic Absorption techniques were used to study the Chemical, Mineral, Compositions Concentrations (of Some Metals). In addition, the Natural Radioactivity measurements of <sup>226</sup>Ra, <sup>232</sup>Th and <sup>40</sup>K, was used by a high-purity germanium (HPGe) detector. X-ray diffraction results showed that the major mineral constituents of 15 samples were quartz (SiO<sub>2</sub>) (except one), minor and trace elements vary from sample to sample. Atomic absorption spectroscopy results of the concentrations for (Al, Pb, Bi, U, Th and K) in (ppm) showed that Al<sub>2</sub>O average was 10.3 (ppm) (10%) less than the acceptable value. PbO, its average was 1.65 ppm which was slightly greater than the allowed value 1.35 ppm. Bi concentrations for all samples were lower than (DL < 10). For most samples U, concentrations were lower than (DL < 5) except samples C9 and C11. Th concentrations ranged from LDL (<1 to 52.88) and were much greater than the acceptable value 7.24 ppm except samples P1, P2, P4. The potassium concentration average was greater than the acceptable value. The average concentrations of <sup>238</sup>U, <sup>232</sup>Th and <sup>40</sup> K were (83.83, 91.05 and 751.07) Bq/kg dry. The radium equivalent activity concentration <em>Ra</em><sub><em>eq</em></sub> (Bq/kg) (302.61) was less than recommended value (370), gamma dose rate <em>D</em> (nGy/h) average (140.15) was much higher than the recommended value (60) (UNSCEER). <em>D</em><sub><em>eff</em></sub> (mSv/year) and <em>H</em><sub><em>ix</em></sub> were below the published admissible limit ≤ 1 and the risk is negligible. This study offers needed information for consumers at exposure risk and is useful to be found in terms of radiation protection.
文摘Natural radioactivity is a source of continuous exposure to human beings. The natural radioactivity due to the presence of 226Ra, 232Th and 40K in sand samples collected from Ad-Dahna was measured by means of HPGe. The measured activity concentrations of radionuclides were compared with the worldwide reported data. Mean measured activity concentrations of 226Ra, 232Th and 40K varied between 16.2 - 30.6, 15.8 - 36.7 and 285.3 - 533.2 Bq·kg–1 respectively with a mean value of 23.4 ± 4.3 Bq·kg–1, 29.7 ± 5.9 Bq·kg–1 and 380 ± 65 Bq·kg–1 respectively. Mean values of radium equivalent activity, absorbed dose rate and external radiation hazard index were 106 ± 8 Bq·kg–1, 51.4 nGy·h–1 and 0.29 respectively. The annual effective radiation dose was calculated to be 0.32 mSv·y–1. The Raeq values of sand samples are lower than the limit of 370 Bq·kg–1, equivalent to a gamma dose of 1.5 mSv·yr–1.This study shows that the measured sand samples do not pose any significant source of radiation hazard and are safe for use in building materials.
文摘In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) for thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The mean values of the activity concentrations of U-238 (Ra-226), Th-232, K-40 and Cs-137 in the igneous samples are found as (11.0, 11.50, 1172.71, 1.47) Bq/Kg respectively. In the sedimentary rocks, the mean values of the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) equal to (12.04, 13.18, 1131.36, 1.60) Bq/Kg respectively. The averages of radiological hazards (<em>Ra</em><sub><em>eq</em></sub>, <em>H</em><sub><em>ex</em></sub> and <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">γ</span></span></em></sub>) were calculated and found to be within the UNSCEAR permissible limit values (370 Bq/kg for <em>Ra</em><sub><em>eq</em></sub>, and 1 for <em>H</em><sub><em>ex</em></sub> and <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">γ</span></span></em></sub>), except for a slight increase of average value of <em>I</em><sub><em><span style="white-space:nowrap;"><span style="white-space:nowrap;">γ</span></span></em></sub> in the igneous rock samples (1.36). The results indicate that the dose rate values depend on the kind of rocks (high in some igneous rock samples, and most of sedimentary rock samples have low dose rate). The activities of naturalnuclides were predicted and simulated in T time using a written MATLAB R2020a script based on the average activity concentrations and respective half-lives of U-238 and Th-232 series, and K-40, this is to evaluate the future effects of natural radionuclides on the population and estimate the human inputs in the future.
基金fnancially supported by the National Key Project of Science and Technology for Development of Large-size Oil&Gas Fields and Coal-bed Gas(Grant No.2008ZX05003-002)by the State Key Laboratory of Petroleum Resources and Prospecting(No.prp2009-02)The study is a contribution to IGCP#592 Project
文摘The unconformity surface at the bottom of the Paleogene is one of the most important migration pathways in the Sikeshu Sag of the Junggar Basin,which consists of three layers:upper coarse clastic rock,lower weathering crust and leached zone.The upper coarse clastic rock is characterized by higher density and lower SDT and gamma-ray logging parameters,while the lower weathering crust displays opposite features.The transport coefficient of the unconformity surface is controlled by its position in respect to the basal sandstone; it is higher in the ramp region but lower in the adjacent uplifted and sag areas.The content of saturated hydrocarbons increases with the decrease of the content of nonhydrocarbons and asphaltenes.The content of benzo[c] carbazole decreases as the content of benzo[a]carbazole and [alkyl carbazole]/[alkyl + benzo carbazole] increases.This suggests that the unconformity surface is an efficient medium for the transportation of hydrocarbons.
基金Supported by National High Technology Research and Development Program of China(2013AA064702)National Major Special Well logging Company of Shengli Petroleum Administration Bureau of Sinopec Group(2011ZX05006-002)
文摘Spectrum analysis of natural gamma ray spectral logging (SGR) data is a critical part of surface informa- tion processing systems. Due to the low resolution, which is an inherent weakness of SGR, and the low signal-to-noise ratio problem of logging measurements, SGR is usually treated with a low confidence level. The Direct Demodulation (DD) method is an advanced technique to solve modulation equations interactively under physical constraints. It has higher sensitivity and spatial resolution than the traditional methods and can effectively suppress the logging noise. Based on standard count rate spectral data obtained from the China Offshore Oil Logging Company SGR Calibration Facility, this paper presents the application of the DD method to gamma-ray logging. The results are compared with four traditional algorithmic methods, showing that the DD method is a credible choice, with higher sensitivity and higher spatial resolution in gamma-ray log interpretation. The Point-Spread-Function of the Shengli Oil Logging Company's natural gamma ray spectroscopy instrument is obtained for the first time. The quantities of various radionuclides in their calibration pits are also obtained. The DD method was applied successfully to gamma-ray logging, offering a new option for SGR logging algorithm selection.