期刊文献+
共找到8,306篇文章
< 1 2 250 >
每页显示 20 50 100
Variations in evaporation from water surfaces along the margins of the Badain Jaran Desert over nearly 60 years and influencing factors 被引量:1
1
作者 Li-juan Wang Zhe Wang +3 位作者 Gao-lei Jiang Zhen-long Nie Jian-mei Shen Sheng-hua Song 《Journal of Groundwater Science and Engineering》 2024年第3期253-263,共11页
Based on meteorological data collected over nearly 60 years(1960-2017)from four national meteorological stations along the margins of the Badain Jaran Desert,this study analyzed the spatiotemporal variations in evapor... Based on meteorological data collected over nearly 60 years(1960-2017)from four national meteorological stations along the margins of the Badain Jaran Desert,this study analyzed the spatiotemporal variations in evaporation from water surfaces and identified the dominant controlling factors.Methods used included linear trend analysis,linear tendency estimation,the departure method,the rank correlation coefficient-based method,and Multiple Linear Regression(MLR).Results indicate notable spatiotemporal differences in evaporation distribution and evolution.Spatially,average annual evaporation exhibited a pronounced altitude effect,decreasing at a rate of about 8.23 mm/m from east to west with increasing altitude.Temporally,annual evaporation showed significant upward trends after 1996 at the northeastern(Guaizi Lake)and western(Dingxin)margins,with rates of 132 mm/10a and 105 mm/10a,respectively.Conversely,along the northwestern(Ejina Banner)and southern(Alxa Right Banner)margins of the desert,an evaporation paradox was observed,with annual evaporation trending downward at rates of 162 mm/10a and 187 mm/10a,respectively,especially after 1987.The dominant factors controlling evaporation varied spatially:Average annual temperature and relative humidity influended the western margin(Dingxin),average annual temperature was the key factor for the northeastern margin(Guaizi Lake),and average wind speed was crucial for the northern(Ejina Banner)and southern(Alxa Right Banner)margins. 展开更多
关键词 Evaporation from water surface Evaporation paradox Dominant controlling factor Variation trend
下载PDF
Disinfection Byproducts and Their Precursors in Drinking Water Sources:Origins,Influencing Factors,and Environmental Insights
2
作者 Rong Xiao Yang Deng +1 位作者 Zuxin Xu Wenhai Chu 《Engineering》 SCIE EI CAS CSCD 2024年第5期36-50,共15页
Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as ... Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as they tend to be laborious,time-consuming,or technically difficult.Disinfection byproducts(DBPs)are a family of well-known secondary pollutants formed by the reactions of chemical disinfectants with DBP precursors during water disinfection treatment.Since DBP precursors have various origins(e.g.,natural,domestic,industrial,and agricultural sources),and since the formation of DBPs from different precursors in the presence of specific disinfectants is distinctive,we argue that DBPs and DBP precursors can serve as alternative indicators to assess the contamination in water sources and identify pollution origins.After providing a retrospective of the origins of DBPs and DBP precursors,as well as the specific formation patterns of DBPs from different precursors,this article presents an overview of the impacts of various natural and anthropogenic factors on DBPs and DBP precursors in drinking water sources.In practice,the DBPs(i.e.,their concentration and speciation)originally present in source water and the DBP precursors determined using DBP formation potential tests—in which water samples are dosed with a stoichiometric excess of specific disinfectants in order to maximize DBP formation under certain reaction conditions—can be considered as alternative metrics.When jointly used with other water quality parameters(e.g.,dissolved organic carbon,dissolved organic nitrogen,fluorescence,and molecular weight distribution)and specific contaminants of emerging concern(e.g.,certain pharmaceuticals and personal care products),DBPs and DBP precursors in drinking water sources can provide a more comprehensive picture of water pollution for better managing water resources and ensuring human health. 展开更多
关键词 Disinfection byproducts Disinfection byproduct precursors Drinking water sources Contamination indicator Natural factors Human factors
下载PDF
Quantitative Evaluation of Heavy Metal Pollution and Its Influencing Factors in Water Bodies of Karst Areas
3
作者 Dijin MU Shizhen XIAO 《Meteorological and Environmental Research》 2024年第1期75-82,共8页
At present, there is relatively little research on the synergistic effects of heavy metals in soil, sediment, and bedrock on heavy metal pollution in water bodies. In this paper, heavy metals in soil, sediment, bedroc... At present, there is relatively little research on the synergistic effects of heavy metals in soil, sediment, and bedrock on heavy metal pollution in water bodies. In this paper, heavy metals in soil, sediment, bedrock, and water of a typical karst watershed in southwest China were investigated. The results indicated that the average values of heavy metals in soil and sediment were relatively higher than those in bedrock except for Ni and As. During the research period, As and Cd were the main heavy metal elements polluting the soil and sediment in the study area, while water bodies were mainly polluted by Ni, As, and Cd. The pollution assessment indicated that there were instances of poor or very poor water quality in the study area during the study period;the soil as a whole was slightly polluted by Cd and As;sediment was subject to moderate Cd pollution and mild As pollution. Analysis of geochemical form for heavy metals showed that heavy metals in soil and sediment were mainly in residual form, and the proportions of exchangeable As and Cd were relatively high. Multiple statistical analysis showed that heavy metals in sediment, soil, and bedrock explained 23.8%, 16.8%, and 16.2% of the changes in heavy metals of water, respectively. The research results can provide scientific basis for the prevention and control of heavy metal pollution in water bodies. 展开更多
关键词 water body SEDIMENT Soil BEDROCK Speciation forms POLLUTION Influence factor
下载PDF
Purification Effects of Aquatic Vegetations on Lake Wetland Water Environment and Analysis of the Influencing Factors in Hongze Lake 被引量:3
4
作者 赵洪波 吴睿 卡林 《Agricultural Science & Technology》 CAS 2012年第1期211-216,共6页
[Objective] To study the purification effect of plant community on wetland water environment in Hongze Lake, and to provide references to the ecological restoration of this area. [Methed] The typical lakeside zone of ... [Objective] To study the purification effect of plant community on wetland water environment in Hongze Lake, and to provide references to the ecological restoration of this area. [Methed] The typical lakeside zone of Hongze Lake Wetland National Nature Reserve was taken as the study area. Through the field survey based on environmental characteristics of aquatic areas and non-aquatic areas, combined with laboratory test, the content changes of nutrients (N and P), COD (chemical oxygen demand) and SD (transparency) levels in the water body of lake wetland were measured; the purification effect of the lake wetland ecosystem in the growth process of aquatic vegetation was quantitatively analyzed, and possible influ- encing factors were discussed. [Result] Aquatic vegetation could remove the TN, TP, COD, Chla in wetland water environment and had obvious effects on the changes of SD content. Competition between aquatic plants can inhibit the growth of algae and relieve the eutrophication of water body. [Conclusion] This study provided theoretical basis for ecological restoration and enhancement of self-purification capability in the lakeside zone of Hongze Lake. 展开更多
关键词 Aquatic vegetation water environment Purification effect Influencing factors
下载PDF
Research Advance on Influencing Factors of Crop Water Use Efficiency 被引量:3
5
作者 周敏 周绍松 +2 位作者 王建新 张忠武 杨景华 《Agricultural Science & Technology》 CAS 2014年第11期1967-1976,共10页
The research advance on the influencing factors of crop water use effi-ciency (WUE) was reviewed in this paper. Based on the discussion on the conno-tation of crop WUE, the influencing factors of crop WUE, such as c... The research advance on the influencing factors of crop water use effi-ciency (WUE) was reviewed in this paper. Based on the discussion on the conno-tation of crop WUE, the influencing factors of crop WUE, such as crop, environ-ment, chemicals, cultivation measures, cropping systems, etc, were elaborated. A-mong them, the species and varieties of crop, soil and chemicals were discussed in detail. 展开更多
关键词 Crop water use efficiency Soil Influencing factor
下载PDF
Influential Factors of Water Productivity of Maize in Oasis of Arid Areas——A Case Study of Linze County
6
作者 胡广录 张济世 樊立娟 《Agricultural Science & Technology》 CAS 2012年第9期1854-1858,共5页
[Objective] The aim was to research influential factors of water productivity of maize in oasis in arid areas. [Method] In middle reach of Heihe River in Linze County of Zhangye City, maize, a major crop in irrigated ... [Objective] The aim was to research influential factors of water productivity of maize in oasis in arid areas. [Method] In middle reach of Heihe River in Linze County of Zhangye City, maize, a major crop in irrigated area in the oasis, was studied and nine influential factors were chosen through grey relation analysis. [Result] According to grey relation analysis, top five factors influencing water produc- tivity of maize during 1995-2009 were as follows: applied quantity of chemical fertil- izers〉labour input〉seeds〉mulch amount〉pesticide amount, which indicated that controllable factors, instead of uncontrollable ones, dominate in influence of water productivity of maize in oasis in arid areas. [Conclusion] With water resource limited, investment of controllable factors in high-efficient agricultural production should be the major strategy to improve water productivity of maize in oasis of arid areas. 展开更多
关键词 MAIZE water productivity Influential factors Gray relation analysis Irri-gated areas in oasis
下载PDF
Influential factors and control of water inrush in a coal seam as the main aquifer 被引量:6
7
作者 Gao Rui Yan Hao +2 位作者 Ju Feng Mei Xianchen Wang Xiulin 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2018年第2期187-193,共7页
In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme... In this paper, a combination of field measurement, theoretical analysis and numerical simulation were used to study the main control factors of coal mine water inrush in a main aquifer coal seam and its control scheme. On the basis of revealing and analyzing the coal seam as the main aquifer in western coal mine of Xiao Jihan coal mine, the simulation software of PHASE-2D was applied to analyze the water inflow under different influencing factors. The results showed that water inflow increases logarithmically with the coal seam thickness, increases as a power function with the permeability coefficient of the coal seam, and increases linearly with the coal seam burial depth and the head pressure; The evaluation model for the factors of coal seam water inrush was gained by using nonlinear regression analysis with SPSS. The mine water inrush risk evaluation partition within the scope of the mining field was obtained,through the engineering application in Xiao Jihan coal mine. To ensure the safe and efficient production of the mine, we studied the coal mine water disaster prevention and control measures of a main aquifer coal seam in aspects of roadway driving and coal seam mining. 展开更多
关键词 COAL SEAM MAIN AQUIFER water inrush Influential factors Control
下载PDF
Influencing factors and mechanism of water absorption process of iron ores during sintering 被引量:2
8
作者 Guo-liang Zhang Sheng-li Wu +1 位作者 Juan Zhu Yong-zhi Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第2期122-130,共9页
The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption... The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption rate (WAR) of four types of iron ores were analyzed by using the immersion method and capillary water absorption method. In addition, the mechanism underlying the water absorption process in iron ores was unraveled. It is found that the WARs of iron ores decrease quickly with the increase in water absorption time at the initial stages of water absorption. With further increase in absorption time, the WARs decrease gradually, until near 0. Iron ores with higher porosity, smaller particle size, and plate-like structure have the higher WARs. Compared with pores in the single-particle iron ore, voids among particles in the multi-particle iron oxide play an important role at the initial stages of water absorption. The water absorption mechanism of all single-particle and multi-particle iron ores analyzed in this study includes four steps, wherein the first three steps play a significant role in the sintering pro-cess. 展开更多
关键词 iron ores SINTERING water absorption factor analysis
下载PDF
Architecture mode, sedimentary evolution and controlling factors of deepwater turbidity channels: A case study of the M Oilfield in West Africa 被引量:2
9
作者 Wen-Biao Zhang Tai-Zhong Duan +3 位作者 Zhi-Qiang Liu Yan-Feng Liu Lei Zhao Rui Xu 《Petroleum Science》 SCIE CAS CSCD 2017年第3期493-506,共14页
Turbidity channels have been considered as one of the important types of deepwater reservoir, and the study of their architecture plays a key role in efficient development of an oil field. To better understand the res... Turbidity channels have been considered as one of the important types of deepwater reservoir, and the study of their architecture plays a key role in efficient development of an oil field. To better understand the reservoir architecture of the lower Congo Basin M oilfield, semiquantitative–quantitative study on turbidity channel depositional architecture patterns in the middle to lower slopes was conducted with the aid of abundant high quality materials(core, outcrop, logging and seismic data),employing seismic stratigraphy, seismic sedimentology and sedimentary petrography methods. Then, its sedimentary evolution was analyzed accordingly. The results indicated that in the study area, grade 3 to grade 5 architecture units were single channel, complex channel and channel systems, respectively. Single channel sinuosity is negatively correlated with the slope, as internal grains became finer and thickness became thinner from bottom to top, axis to edge. The migration type of a single channel within one complex channel can be lateral migration and along paleocurrent migration horizontally, and lateral,indented and swing stacking in section view. Based on external morphological characteristics and boundaries,channel systems are comprised of a weakly confining type and a non-confining type. The O73 channel system can be divided into four complex channels named S1–S4, from bottom to top, with gradually less incision and more accretion. The study in this article will promote deeper understanding of turbidity channel theory, guide 3D geological modeling in reservoir development and contribute to efficient development of such reservoirs. 展开更多
关键词 Reservoir architecture Turbidity channelSedimentary evolution Deep water Shallow seismicControlling factors
下载PDF
Seismic performance evaluation of water supply pipes installed in a full-scale RC frame structure based on a shaking table test 被引量:1
10
作者 Wu Houli Guo Endong +2 位作者 Wang Jingyi Dai Xin Dai Chenxi 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期163-178,共16页
As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much attention.This paper presents shaking table test research on water supply pipes installed in a full-scal... As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much attention.This paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame structure.Different material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic performance.Floor response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical simulation.The acceleration response and displacement response of different combinations are compared.The results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes. 展开更多
关键词 water supply pipe different materials shaking table test amplification factor seismic fragility
下载PDF
Effects of natural mineral-rich water consumption on the expression of sirtuin 1 and angiogenic factors in the erectile tissue of rats with fructose-induced metabolic syndrome 被引量:2
11
作者 Cidalia D Pereira Milton Severo +2 位作者 Luisa Rafael Maria Joao Martins Delminda Neves 《Asian Journal of Andrology》 SCIE CAS CSCD 2014年第4期631-638,共8页
Consuming a high-fructose diet induces metabolic syndrome (MS)-Iike features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular diseas... Consuming a high-fructose diet induces metabolic syndrome (MS)-Iike features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular disease. Because mineral deficiency intensifies the deleterious effects of fructose consumption and mineral ingestion is protective against MS, we aimed to characterize the effects of 8weeks of natural mineral-rich water consumption on the structural organization and expression of vascular growth factors and receptors on the corpus cavernosum (CC) in 10% fructose-fed Sprague-Dawley rats (FRUCT). Differences were not observed in the organization of the CC either on the expression of vascular endothelial growth factor (VEGF) or the components of the angiopoietins/Tie2 system. However, opposing expression patterns were observed for VEGF receptors (an increase and a decrease for VEGFR1 and VEGFR2, respectively) in FRUCT animals, with these patterns being strengthened by mineral-rich water ingestion. Mineral-rich water ingestion (FRUCTMIN) increased the proportion of smooth muscle cells compared with FRUCT rats and induced an upregulatory tendency of sirtuin I expression compared with the control and FRUCT groups. Western blot results were consistent with the dual immunofluorescence evaluation. Plasma oxidized low-density lipoprotein and plasma testosterone levels were similar among the experimental groups, although a tendency for an increase in the former was observed in the FRUCTMIN group. The mineral-rich water-treated rats presented changes similar to those observed in rats treated with MS-protective polyphenol-rich beverages or subjected to energy restriction, which led us to hypothesize that the effects of mineral-rich water consumption may be more vast than those directly observed in this study. 展开更多
关键词 ANGIOPOIETINS erectile tissue hypersaline sodium-rich naturally sparkling mineral water receptors sirtuin 1 vascularendothelial growth factor
下载PDF
Control factors of DIC in the Y3 seamount waters of the Western Pacific Ocean 被引量:4
12
作者 MA Jun SONG Jinming +4 位作者 LI Xuegang YUAN Huamao LI Ning DUAN Liqin WANG Qidong 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2020年第4期1215-1224,共10页
An investigation was carried out in the Y3 seamount area of the Western Pacific Ocean in December 2014,and the distribution of dissolved inorganic carbon(DIC)and its relationship with environmental factors in this are... An investigation was carried out in the Y3 seamount area of the Western Pacific Ocean in December 2014,and the distribution of dissolved inorganic carbon(DIC)and its relationship with environmental factors in this area were explored.The results show that DIC concentration was higher in the adjacent waters of the Y3 seamount area,and the uplift of DIC isolines at the stations was close to the seamount.Meanwhile,interaction between the North Equatorial Current(NEC)and the Y3 seamount affected the DIC distribution,i.e.,the upwelling in the same direction of the NEC was obvious,resulting in a decreasing trend of average concentration of DIC in the 200 m water column from the top to the two sides in this direction but in the cross direction.The DIC concentration increased with the water depth increase,and its distribution was affected by various environmental factors.In the surface water,high temperature was a decisive factor for the decrease of the DIC concentration,but the photosynthesis of phytoplankton showing only a weak influence.In the North Pacific Tropic Water(NPTW),DIC production rate from organic matter decomposition was higher than that of DIC consumption by phytoplankton photosynthesis,leading to a continual increase of DIC.In the North Pacific Intermediate Water(NPIW),organic matter decomposition played a leading role in the increase of DIC.In the deep water,decomposition of organic matter weakened,and the dissolution of CaCO3 controlled the carbonate system,and DIC had the smallest variation range. 展开更多
关键词 dissolved inorganic carbon(DIC) Western Pacific Ocean Y3 seamount water masses environmental factors
下载PDF
Relationship Between the Spatiotemporal Distribution of Dominant Small Pelagic Fishes and Environmental Factors in Mauritanian Waters 被引量:1
13
作者 EBANGO NGANDO Narcisse SONG Liming +1 位作者 CUI Hongxing XU Shuangquan 《Journal of Ocean University of China》 SCIE CAS CSCD 2020年第2期393-408,共16页
The relationship between the spatiotemporal distribution of three dominant small pelagic fishes,including chub mackerel(Scomber japonicus),horse mackerel(Trachurus trecae)and round sardinella(Sardinella aurita),and th... The relationship between the spatiotemporal distribution of three dominant small pelagic fishes,including chub mackerel(Scomber japonicus),horse mackerel(Trachurus trecae)and round sardinella(Sardinella aurita),and the environmental factors in Mauritanian waters were analyzed by using 4 years of logbook data of commercial purse seine fisheries to improve the efficiency of fishery and management of sustainable exploitation.A Tweedie-generalized additive model(GAM)of 8-day average catches and the monthly geostatistical analysis of daily catches were used in this study to analyze the influence of environmental factors on catch per unit of effort(CPUEs)and to map the spatial distribution of three mixed dominant small pelagic fishes,respectively.A 10'×10' grid was used,and environmental factors were processed from remote sensing,including 8-day average sea surface temperature(SST),the nearest distance between SST fronts and CPUE position(Df),chlorophyll-a(Chl-a)concentration,salinity,and eddy kinetic energy.Results showed that 1)the distribution of three dominant small pelagic fishes might be related to the intensity of upwelling in Mauritanian waters;2)oceanic fronts might play a key role in the ecology of chub mackerel,horse mackerel,and round sardinella;3)Chl-a concentration might be associated with the feeding grounds of chub mackerel;4)the target species distribution appeared sensitive to gradient changes in the amount of salinity;5)three zones(northern,central,and southern)with variable abundances were delineated;and 6)a high concentration of the center of gravity in the central zone might be related to the strong upwelling of nutrient-rich waters.This study can provide new insights to enhance the fishery efficiency and sustainable exploitation management of purse seiners in certain area off Mauritania. 展开更多
关键词 AGGREGATION environmental factors small pelagic fish light purse seiner Mauritanian waters
下载PDF
An Analysis of Water Environment Factors and an Evaluation of Water Quantity of Liangzi Lake 被引量:2
14
作者 Hong Wang Junlan Yao Yanqiang Li 《Journal of Geoscience and Environment Protection》 2016年第7期44-51,共8页
The experiments of single factor evaluation method, principal component analysis and voronoi area weighting factor method on the sample data of Liangzi Lake in October 2012 combined with the national surface water env... The experiments of single factor evaluation method, principal component analysis and voronoi area weighting factor method on the sample data of Liangzi Lake in October 2012 combined with the national surface water environment quality standards can get the map of comprehensive water quality distribution by Kriging interpolation. The analysis shows, the grades of comprehensive water quality gained by three methods are all only class III or class IV, and the quality of water is different from east and west that the water quality of east is better. However, the percent of IV class water is higher in the result of single factor evaluation method means class IV is the main grade of water quality. The result of principal component analysis shows the percent of class Ⅲ water is higher than other classes. The result of voronoi area weighting factor method shows the percent of IV class is higher than other classes. COD<sub>Mn</sub> is the main factor that influences the method of singal factor evaluation and reduces the grade of water quality overall. The effect of single factor is reduced by principal component analysis, and the analysis on water quality is more accurate. The voronoi area weighing factor method reduces the effect of single factor and extends the content, can make a comprehensive evaluation on water quality. 展开更多
关键词 factor Analysis PCA VORONOI Area Weighting Method water Quality Assessment
下载PDF
Relationship between the Water Body Chlorophylla and Water Quality Factors of Wetlands Baiguishan Reservoir 被引量:1
15
作者 SHE Qiu-sheng TIAN Xun WANG Guo-zhen JI Xiao-cun LI Jiu-xuan ZHAO Zhen 《Agricultural Science & Technology》 CAS 2011年第4期581-583,591,共4页
[Objective] The aim was to explore the relationship between water body Chlorophyll-a and water quality factors of wetlands Baiguishan reservoir.[Method] Chlorophyll-a and water quality factors of water quality of Wetl... [Objective] The aim was to explore the relationship between water body Chlorophyll-a and water quality factors of wetlands Baiguishan reservoir.[Method] Chlorophyll-a and water quality factors of water quality of Wetlands BaiGuishan Reservoir was studied,the analysis of the relationship on water quality of Wetlands Baiguishan Reservoir was made by use of trophic status indices and SPSS17.0 statistical analysis.[Result] Total phosphorus was an important factor of influence Chlorophyll-a in reservoir,water body had slight eutrophication phenomenon in reservoir of July to October in 2010.[Conclusion] Comprehensive management should be strengthened so as to improve the water quality of Baiguishan wetland. 展开更多
关键词 Wetlands Baiguishan Reservoir CHLOROPHYLL-A water quality factors RELATIONSHIP
下载PDF
Variation Laws and Influencing Factors of pH in Fishery Waters in Quzhou City 被引量:1
16
作者 Qinxuan SHI Xueping YE +4 位作者 Dongren ZHOU Sheng GAO Qifang WU Feng LIN Ting YE 《Agricultural Biotechnology》 CAS 2021年第1期69-73,共5页
[Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlor... [Objectives] This study was conducted to strengthen the understanding of the variation laws of pH in fishery waters. [Methods]Based on the investigation data of pH, dissolved oxygen(Do), water temperature(T) and chlorophyll a(Chl. a) of the fishery waters in Quzhou City from 2017 to 2020, the seasonal variation characteristics and influencing factors of pH in the fishery waters were analyzed and discussed. [Results] The pH of the fishery waters in Quzhou City was in the range of 6.40-11.3, and was characterized by the highest seasonal variation in spring and the lowest in winter. The correlation analysis showed that water temperature and pH were significantly positively correlated in spring and summer(P<0.05), and the photosynthesis of phytoplankton was the main reason that affected the pH of water bodies in spring and summer. There was a negative correlation between water temperature and pH in winter, and the pH in the natural waters had a significant negative correlation with water temperature(P<0.05). The balance of carbonate system in the water bodies was the main reason that affected the pH of water in winter. The level of water eutrophication(Chl. a) affected the pH of fishery waters to a certain extent. When Chl. a<10 μg/L, there was a significant positive correlation between the pH of fishery waters and Chl. a(P<0.05). Various environmental factors had different effects on the pH of different types of fishery waters. The stepwise regression analysis showed that the pH of natural waters was mainly affected by Chl. a, and the pH of aquaculture waters was mainly affected by water temperature and dissolved oxygen. [Conclusions]This study provides certain theoretical support for actual production management. 展开更多
关键词 Fishery waters PH Influencing factors CORRELATION
下载PDF
Exploring groundwater quality in semi-arid areas of Algeria:Impacts on potable water supply and agricultural sustainability
17
作者 Noua ALLAOUA Hinda HAFID Haroun CHENCHOUNI 《Journal of Arid Land》 SCIE CSCD 2024年第2期147-167,共21页
Groundwater quality assessment is important to assure safe and durable water use.In semi-arid areas of Algeria,groundwater represents the main water resource for drinking water supply of the rural population as well a... Groundwater quality assessment is important to assure safe and durable water use.In semi-arid areas of Algeria,groundwater represents the main water resource for drinking water supply of the rural population as well as for irrigation of agricultural lands.Groundwater samples from wells and springs were collected from the Gargaat Tarf and Annk Djemel sub-watersheds of the Oum El Bouaghi,Algeria,and were analyzed and compared with the World Health Organization(WHO)standards.Results showed that most of the measured physical and chemical parameters exceeded the quality limits according to the WHO standards.Groundwater had a slightly alkaline water pH(7.00-7.79),electrical conductivity>1500μS/cm,chloride>500 mg/L,calcium>250 mg/L,and magnesium>155 mg/L.Water quality index(WQI)results showed that 68%of the area had excellent water quality,24%of the samples fell into good category,and only 8%were of poor quality and unsuitable for human consumption.Six wells in the area showed bacterial contamination.Total coliforms(453.9(±180.3)CFU(colony-forming units)/100 mL),fecal coliforms(243.2(±99.2)CFU/100 mL),and fecal streptococci(77.9(±32.0)CFU/100 mL)loads were above the standard limits set by the WHO.These results confirmed that water resources in the study area were strongly influenced by anthropogenic activities and were not recommended for consumption as drinking water. 展开更多
关键词 bacteriological indicator GROUNDwater waterSHED physical-chemical parameter water quality index
下载PDF
A Calculation Method of Double Strength Reduction for Layered Slope Based on the Reduction of Water Content Intensity
18
作者 Feng Shen Yang Zhao +1 位作者 Bingyi Li Kai Wu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第1期221-243,共23页
The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties... The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties of different soil layers of the slopes are different,so the single coefficient strength reduction method(SRM)is not enough to reflect the actual critical state of the slopes.Considering that the water content of the soil in the natural state is the main factor for the strength of the soil,the attenuation law of shear strength of clayey soil changing with water content is fitted.This paper also establishes the functional relationship between different reduction coefficients.Then,a USDFLD subroutine is programmed using the secondary development function of finite element software.Controlling the relationship between field variables and calculation time realizes double strength reduction applicable to the layered slope.Finally,by comparing the calculation results of different examples,it is proved that the stress and displacement distribution of the critical slope state obtained by the improved method is more realistic,and the calculated safety factor is more reliable.The newly proposedmethod considers the difference of intensity attenuation between different soil layers under natural conditions and avoids the disadvantage of the strength reduction method with uniform parameters,which provides a new idea and method for stability analysis of layered and complex slopes. 展开更多
关键词 Double strength reduction slopes stability water content factor of safety numerical methods
下载PDF
Gas-Water Production of a Continental Tight-Sandstone Gas Reservoir under Different Fracturing Conditions
19
作者 Yan Liu Tianli Sun +1 位作者 Bencheng Wang Yan Feng 《Fluid Dynamics & Materials Processing》 EI 2024年第6期1165-1180,共16页
A numerical model of hydraulic fracture propagation is introduced for a representative reservoir(Yuanba continental tight sandstone gas reservoir in Northeast Sichuan).Different parameters are considered,i.e.,the inte... A numerical model of hydraulic fracture propagation is introduced for a representative reservoir(Yuanba continental tight sandstone gas reservoir in Northeast Sichuan).Different parameters are considered,i.e.,the interlayer stress difference,the fracturing discharge rate and the fracturing fluid viscosity.The results show that these factors affect the gas and water production by influencing the fracture size.The interlayer stress difference can effectively control the fracture height.The greater the stress difference,the smaller the dimensionless reconstruction volume of the reservoir,while the flowback rate and gas production are lower.A large displacement fracturing construction increases the fracture-forming efficiency and expands the fracture size.The larger the displacement of fracturing construction,the larger the dimensionless reconstruction volume of the reservoir,and the higher the fracture-forming efficiency of fracturing fluid,the flowback rate,and the gas production.Low viscosity fracturing fluid is suitable for long fractures,while high viscosity fracturing fluid is suitable for wide fractures.With an increase in the fracturing fluid viscosity,the dimensionless reconstruction volume and flowback rate of the reservoir display a non-monotonic behavior,however,their changes are relatively small. 展开更多
关键词 Tight sandstone gas reservoir fracture propagation flowback rate gas production law water production law influencing factor
下载PDF
The Impact and Intervention of Handheld Tai Chi Water-Resistance Fitness Ball on Middle-Aged and Elderly Patients with Parkinson’s Disease
20
作者 He Huang 《Health》 2024年第4期319-349,共31页
Through the use of a survey and statistical methods, this study explores the effects and interventions of handheld Tai Chi water resistance fitness balls on the elderly with Parkinson’s disease. Firstly, a questionna... Through the use of a survey and statistical methods, this study explores the effects and interventions of handheld Tai Chi water resistance fitness balls on the elderly with Parkinson’s disease. Firstly, a questionnaire on exercise compliance for patients with Parkinson’s disease was developed, and its reliability and validity were tested. Then, a survey was conducted to investigate the current status of exercise compliance among Parkinson’s disease patients, including general information, scoring status, and single and multiple factor analyses of influencing factors [1]. The results of the study show that through qualitative research, the dimensions and item pools of the questionnaire were initially constructed, and the reliability analysis of the questionnaire was conducted through Delphi expert consultation, with favorable results in terms of its reliability and validity [2]. Regarding the current status of exercise compliance among Parkinson’s disease patients, the study found that the level of exercise compliance needs improvement, and there are significant differences in exercise compliance levels among patients under different circumstances. Finally, the research results were discussed and conclusions were drawn. The innovation of this study lies in the development of a questionnaire on exercise compliance for patients with Parkinson’s disease and the preliminary qualitative research and Delphi expert consultation conducted on it, providing new ideas and methods for the study of exercise compliance. However, the study also has limitations as it did not examine the effects of other interventions on Parkinson’s disease, so further research should be conducted [3]. 展开更多
关键词 Parkinson’s Disease Exercise Compliance Tai Chi water Resistance Fitness Ball Influencing factors Intervention Effectiveness
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部