Mountainous ecosystems are considered highly sensitive and vulnerable to natural disasters and cli- rnatic changes. Therefore, quantifying the effects of elevation on grassland productivity to understand ecosys- tem-c...Mountainous ecosystems are considered highly sensitive and vulnerable to natural disasters and cli- rnatic changes. Therefore, quantifying the effects of elevation on grassland productivity to understand ecosys- tem-climate interactions is vital for mountainous ecosystems. Water-use efficiency (WUE) provides a useful index for understanding the metabolism of terrestrial ecosystems as well as for evaluating the degradation of grasslands. This paper explored net primary productivity (NPP) and WUE in grasslands along an elevational gradient ranging from 400 to 3,400 m asl in the northern Tianshan Mountains-southern Junggar Basin (TMJB), Xinjiang of China, using the Biome-BGC model. The results showed that: 1 ) the NPP increased by 0.05 g C/(m2-a) with every increase of 1-m elevation, reached the maximum at the mid-high elevation (1,600 m asl), and then decreased by 0.06 g C/(m2.a) per 1-m increase in elevation; 2) the grassland NPP was positively correlated with temperature in alpine meadow (AM, 2,700-3,500 m asl), mid-mountain forest meadow (MMFM, 1,650-2,700 m asl) and low-mountain dry grassland (LMDG, 650-1,650 m asl), while positive correlations were found between NPP and annual precipitation in plain desert grassland (PDG, lower than 650 m asl); 3) an increase (from 0.08 to 1.09 g C/(m2.a)) in mean NPP for the grassland in TMJB under a real climate change scenario was observed from 1959 to 2009; and 4) remarkable differences in WUE were found among different elevations, in general, WUE increased with decreasing elevation, because water availability is lower at lower elevations; however, at elevations lower than 540 m asl, we did observe a decreasing trend of WUE with decreasing elevation, which may be due to the sharp changes in canopy cover over this gradient. Our research suggests that the NPP simulated by Biome-BGC is consistent with field data, and the modeling provides an opportunity to further evaluate interactions between environmental factors and ecosystem productivity.展开更多
Subsurface water flow velocity influences the hydrodynamic characteristics of soil seepage and the interaction between subsurface water flow and surface runoff during soil erosion and sediment transport.A visualized m...Subsurface water flow velocity influences the hydrodynamic characteristics of soil seepage and the interaction between subsurface water flow and surface runoff during soil erosion and sediment transport.A visualized method and equipment was adopted in this study to observe the subsurface water flow.Quartz sand was used as the test material of subsurface water flow and fluorescent dye was used as the indicator for tracing subsurface water flow.Water was supplied at the same flow discharge to the three parts at the bottom of the test flume,and the subsurface water flow were determined with four slope gradients(4°,8°,10°,and 12°).The results showed that the seepage velocity gradually increased with increasing slope gradient.The pore water velocity at different depths of sand layer profile increased with increasing slope gradient,whereas the thickness of the flow front gradually decreased.For the same slope gradient,the pore water velocity in the lower layer was the largest,whereas the thickness of the flow front was the smallest.Comparative analysis of the relationship between seepage velocity and pore water velocity at different depths of sand layer profile showed that the maximum relative difference between the measured pore water velocity and the computational pore water velocity at different depths of sand profile in the experiment was 4.38%.Thus,the test method for measuring the subsurface water flow velocity of sand layer profile adopted in this study was effective and feasible.The development of this experiment and the exploration of research methods would lay a good test foundation for future studies on the variation law of subsurface water flow velocity and the determination of flow velocity in purple soils,thus contributing to the improvement of the hydrodynamic mechanism of purple soils.展开更多
Sedimentation dynamics of magnetite (γ-Fe3O4) nanopowders (10 - 20 nm) in water in the presence of a gradient magnetic field was studied by optical and Nuclear Magnetic Resonance (NMR) relaxometry methods. The magnet...Sedimentation dynamics of magnetite (γ-Fe3O4) nanopowders (10 - 20 nm) in water in the presence of a gradient magnetic field was studied by optical and Nuclear Magnetic Resonance (NMR) relaxometry methods. The magnetic field B ≤ 0.3 T, dB/dz ≤ 0.13 T/cm was produced by the system of permanent strip magnets. The initial sedimentation rate of the nanoparticles in water and under magnetic fields is higher for less concentrated suspensions (c0 = 0.1 g/l) than for more concentrated ones (c0 = 1 g/l). This might be connected with the formation of gel structures due to strong magnetic attraction between ferromagnetic nanoparticles. In the gravitation field, the suspensions of the particles (10 - 20 nm) remain stable for over 20 hours. The sedimentation process can be greatly accelerated by the action of a vertical gradient magnetic field, reducing the sedimentation time down to several minutes. In a gradient magnetic field enhanced by a steel grid, sedimentation of the nanopowder (c0 = 0.1 g/l) for 180 minutes resulted in reduction of the iron concentration in water down to 0.4 mg/l. In flowing water regime, the residual iron concentration in water 0.3 mg/l is reached after 80 minutes.展开更多
The geological conditions of shallow offshore delta oil reservoirs are complex. Under the condition of less well data and larger well spacing, the traditional reservoir configuration method is difficult to solve the d...The geological conditions of shallow offshore delta oil reservoirs are complex. Under the condition of less well data and larger well spacing, the traditional reservoir configuration method is difficult to solve the detailed study of such reservoirs in offshore oil fields. Based on the comprehensive analysis of the seismic phase, data of well log. The paper identifies criteria of the quaternary configuration boundary in shallow water delta of different types with distributary sand dam is established. At the same time, this paper used sensitive factor to construct the edge detection operator based on the amplitude attribute, characterizing the boundary of sand body thickness mutation or physical property mutation quantitatively, realizing the quantitative characterization of four-stage configuration boundary in the region with no wells or few wells, guiding the efficient development of offshore shallow water delta oilfield, and realizing the increase of storage and production of Bohai oilfield.展开更多
This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A g...This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur.The photo synthetic,chlorophyll fluorescence and stem sap flow parameters of P.sepium were measured under a range of water conditions.The different soil water conditions were classified according to the responses of these parameters.(1)With the increase in the relative water content(RWC)of the shell sand,the parameters of leaf photosynthesis,chlorophyll fluorescence and water-related physiology in P.sepium showed significant critical responses.The net photo synthetic rate(Pn),transpiration rate(Tr),instantaneous water use efficiency(WUE),potential water use efficiency(WUEi),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(ΦPSII)and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC,but the corresponding water conditions associated with their maximum values were not the same.An RWC of 69.40%was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P.sepium.At an RWC of 36.61%,the mechanism of photosynthetic inhibition in P.sepium changed from stomatal limitation to nonstomatal limitation;this was also the minimum water requirement for maintaining normal photo synthetic processes.An RWC of 50.27%resulted in the highest WUE in P.sepium,indicating that moderate drought stress increased WUE.(2)Based on the quantitative relationship between the photo synthetic parameters of P.sepium and the shell sand water gradient,the soil water availability was classified into 6 water grades.The RWC range for maintaining strong photosynthesis and high WUE in P.sepium was 63.22-69.98%.(3)Gas exchange in P.sepium was inhibited under drought and waterlogging stresses.Under these conditions,the photosynthetic electron transport chain was blocked,and the dissipation of light energy as heat increased,which ultimately led to a decline in photo synthetic productivity;moreover,transpiration and dissipation were aggravated,and water transmission and utilization processes in P.sepium were hindered.A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P.sepium was observed;this mechanism allowed P.sepium growing in shell sand to be highly adaptable to water stress.展开更多
River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help...River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help in developing an effective catchment management strategy to protect precious water resources. This study analyzed river water quality, patterns of terrestrial and riparian ecosystems, intensity of agricultural activities, industrial structure, and spatial distribution of pollutant emissions in the Haihe River Basin in China for the year of 2010, identifying the variables that have the greatest impact on river water quality. The area percentage of farmland in study area, the percentage of natural vegetation cover in the 1000-m riparian zone, rural population density, industrial Gross Domestic Product(GDP)/km^2, and industrial amino nitrogen emissions were all significantly correlated with river water quality(P < 0.05). Farming had the largest impact on river water quality, explaining 43.0% of the water quality variance, followed by the coverage of natural vegetation in the 1000-m riparian zone, which explained 36.2% of the water quality variance. Industrial amino nitrogen emissions intensity and rural population density explained 31.6% and 31.4% of the water quality variance, respectively, while industrial GDP/km^2 explained 26.6%. Together, these five indicators explained 67.3% of the total variance in water quality. Consequently, water environmental management of the Haihe River Basin should focus on adjusting agricultural activities, conserving riparian vegetation, and reducing industrial pollutant emissions by optimizing industrial structure. The results demonstrate how human activities drive the spatial pattern changes of river water quality, and they can provide reference for developing land use guidelines and for prioritizing management practices to maintain stream water quality in a large river basin.展开更多
Objective To analyze the structure of bacteria in drinking water by molecular biological techniques, Methods DNA of bacteria in drinking water was directly extracted without culture. 16S ribosomal DNA fragments, inclu...Objective To analyze the structure of bacteria in drinking water by molecular biological techniques, Methods DNA of bacteria in drinking water was directly extracted without culture. 16S ribosomal DNA fragments, including V-6, -7, and -8 regions, were amplified with universal primers (EUBf933CJC and EUBr1387) and analyzed by DGGE. Results DGGE indicated that amplification products could be separated, The results showed that DGGE could be used in the separation of different microbial 16SrRNA genes extracted from drinkng water. Though there were special bacteria in different water samples, the predominant bacteria were essentially the same. Three sequences of the reclaimed specific bands were obtained, and phylogenetic tree of these bands was made. Conclusion Bacterial diversity in drinking water is identified by molecular biological techniques.展开更多
It is difficult to obtain a clear image in underwater turbulence environment with classical imaging methods due to the absorption, scattering, and underwater turbulence on the propagation beam.However, ghost imaging(G...It is difficult to obtain a clear image in underwater turbulence environment with classical imaging methods due to the absorption, scattering, and underwater turbulence on the propagation beam.However, ghost imaging(GI), a nonlocally imaging technique, has shown the turbulence-free ability in atmospheric turbulence by exploiting the second-order correlation between the signal beam and the reference beam.In this paper, we experimentally investigate the imaging quality of GI affected by the underwater environment, where the underwater environment is simulated by a 1 m×0.4 m×0.4 m tank with distilled water.The water temperature is controlled by a heater inside the tank, and a temperature gradient is obtained by putting the heater at different positions of the tank.The water vibration is produced by a heavy force, and the turbid medium is obtained by dissolving very small specks of CaCO3 in the water.A set of Hadamard speckle pattern pairs are generated and modulated on the incident beam, and then the beam illuminates on an unknown object after passing through the simulated underwater environment.With the second-order correlations, the image is reconstructed under different temperature gradients, water vibration, and turbid medium ratios.The results show that GI has the turbulence-free ability under lower temperature gradient, water vibration, and turbid media.The structural similarity image measurement(SSIM)values of the reconstructed images only start to decrease when the temperature gradient is greater than 4.0℃.The same temperature gradient produced at the different positions has a little effect on the quality of the underwater GI.展开更多
An analogy between water flux and the field of temperature gradient in a column of wood fuel chips was discovered by these experiments.The heat-mass transfer coeffieient was deter-mined by least squares method.An equa...An analogy between water flux and the field of temperature gradient in a column of wood fuel chips was discovered by these experiments.The heat-mass transfer coeffieient was deter-mined by least squares method.An equation relating water flux and tempetature gradient was devel-opcd and it was demonstrated that the tempeature gradient was the main driving force for watertransport.The meehanism was evaporation-condensation of water vaor through natural convcctionin air phase.The study gives a theoretical exlanation for analyzing the problem of water transport inwood particle material.展开更多
基金funded by the National Natural Science Foundation of China (41271126)the National Basic Research Program of China (2009CB825105)
文摘Mountainous ecosystems are considered highly sensitive and vulnerable to natural disasters and cli- rnatic changes. Therefore, quantifying the effects of elevation on grassland productivity to understand ecosys- tem-climate interactions is vital for mountainous ecosystems. Water-use efficiency (WUE) provides a useful index for understanding the metabolism of terrestrial ecosystems as well as for evaluating the degradation of grasslands. This paper explored net primary productivity (NPP) and WUE in grasslands along an elevational gradient ranging from 400 to 3,400 m asl in the northern Tianshan Mountains-southern Junggar Basin (TMJB), Xinjiang of China, using the Biome-BGC model. The results showed that: 1 ) the NPP increased by 0.05 g C/(m2-a) with every increase of 1-m elevation, reached the maximum at the mid-high elevation (1,600 m asl), and then decreased by 0.06 g C/(m2.a) per 1-m increase in elevation; 2) the grassland NPP was positively correlated with temperature in alpine meadow (AM, 2,700-3,500 m asl), mid-mountain forest meadow (MMFM, 1,650-2,700 m asl) and low-mountain dry grassland (LMDG, 650-1,650 m asl), while positive correlations were found between NPP and annual precipitation in plain desert grassland (PDG, lower than 650 m asl); 3) an increase (from 0.08 to 1.09 g C/(m2.a)) in mean NPP for the grassland in TMJB under a real climate change scenario was observed from 1959 to 2009; and 4) remarkable differences in WUE were found among different elevations, in general, WUE increased with decreasing elevation, because water availability is lower at lower elevations; however, at elevations lower than 540 m asl, we did observe a decreasing trend of WUE with decreasing elevation, which may be due to the sharp changes in canopy cover over this gradient. Our research suggests that the NPP simulated by Biome-BGC is consistent with field data, and the modeling provides an opportunity to further evaluate interactions between environmental factors and ecosystem productivity.
基金This work was supported by the Fundamental Research Funds for the National Natural Science Foundation of China(No.41571265,41971244)the Key Research and Development Project of Social Livelihood in Chongqing(cstc2018jscxmszdX0061)the Foundation of Graduate Research and Innovation in Chongqing under project CYB18089.
文摘Subsurface water flow velocity influences the hydrodynamic characteristics of soil seepage and the interaction between subsurface water flow and surface runoff during soil erosion and sediment transport.A visualized method and equipment was adopted in this study to observe the subsurface water flow.Quartz sand was used as the test material of subsurface water flow and fluorescent dye was used as the indicator for tracing subsurface water flow.Water was supplied at the same flow discharge to the three parts at the bottom of the test flume,and the subsurface water flow were determined with four slope gradients(4°,8°,10°,and 12°).The results showed that the seepage velocity gradually increased with increasing slope gradient.The pore water velocity at different depths of sand layer profile increased with increasing slope gradient,whereas the thickness of the flow front gradually decreased.For the same slope gradient,the pore water velocity in the lower layer was the largest,whereas the thickness of the flow front was the smallest.Comparative analysis of the relationship between seepage velocity and pore water velocity at different depths of sand layer profile showed that the maximum relative difference between the measured pore water velocity and the computational pore water velocity at different depths of sand profile in the experiment was 4.38%.Thus,the test method for measuring the subsurface water flow velocity of sand layer profile adopted in this study was effective and feasible.The development of this experiment and the exploration of research methods would lay a good test foundation for future studies on the variation law of subsurface water flow velocity and the determination of flow velocity in purple soils,thus contributing to the improvement of the hydrodynamic mechanism of purple soils.
文摘Sedimentation dynamics of magnetite (γ-Fe3O4) nanopowders (10 - 20 nm) in water in the presence of a gradient magnetic field was studied by optical and Nuclear Magnetic Resonance (NMR) relaxometry methods. The magnetic field B ≤ 0.3 T, dB/dz ≤ 0.13 T/cm was produced by the system of permanent strip magnets. The initial sedimentation rate of the nanoparticles in water and under magnetic fields is higher for less concentrated suspensions (c0 = 0.1 g/l) than for more concentrated ones (c0 = 1 g/l). This might be connected with the formation of gel structures due to strong magnetic attraction between ferromagnetic nanoparticles. In the gravitation field, the suspensions of the particles (10 - 20 nm) remain stable for over 20 hours. The sedimentation process can be greatly accelerated by the action of a vertical gradient magnetic field, reducing the sedimentation time down to several minutes. In a gradient magnetic field enhanced by a steel grid, sedimentation of the nanopowder (c0 = 0.1 g/l) for 180 minutes resulted in reduction of the iron concentration in water down to 0.4 mg/l. In flowing water regime, the residual iron concentration in water 0.3 mg/l is reached after 80 minutes.
文摘The geological conditions of shallow offshore delta oil reservoirs are complex. Under the condition of less well data and larger well spacing, the traditional reservoir configuration method is difficult to solve the detailed study of such reservoirs in offshore oil fields. Based on the comprehensive analysis of the seismic phase, data of well log. The paper identifies criteria of the quaternary configuration boundary in shallow water delta of different types with distributary sand dam is established. At the same time, this paper used sensitive factor to construct the edge detection operator based on the amplitude attribute, characterizing the boundary of sand body thickness mutation or physical property mutation quantitatively, realizing the quantitative characterization of four-stage configuration boundary in the region with no wells or few wells, guiding the efficient development of offshore shallow water delta oilfield, and realizing the increase of storage and production of Bohai oilfield.
基金supported by the Forestry Science and Technology Innovation Project of Shandong Province(No.2019LY006)the National Natural Science Foundation of China(No.31770761)+1 种基金Open Research Fund Program of Shandong Key Laboratory of Eco-Environmental Science for Yellow River Delta(Binzhou University)(No.2020KFJJ03)the Taishan Scholars Program of Shandong ProvincemChina(No.TSQN201909152)。
文摘This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur.The photo synthetic,chlorophyll fluorescence and stem sap flow parameters of P.sepium were measured under a range of water conditions.The different soil water conditions were classified according to the responses of these parameters.(1)With the increase in the relative water content(RWC)of the shell sand,the parameters of leaf photosynthesis,chlorophyll fluorescence and water-related physiology in P.sepium showed significant critical responses.The net photo synthetic rate(Pn),transpiration rate(Tr),instantaneous water use efficiency(WUE),potential water use efficiency(WUEi),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(ΦPSII)and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC,but the corresponding water conditions associated with their maximum values were not the same.An RWC of 69.40%was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P.sepium.At an RWC of 36.61%,the mechanism of photosynthetic inhibition in P.sepium changed from stomatal limitation to nonstomatal limitation;this was also the minimum water requirement for maintaining normal photo synthetic processes.An RWC of 50.27%resulted in the highest WUE in P.sepium,indicating that moderate drought stress increased WUE.(2)Based on the quantitative relationship between the photo synthetic parameters of P.sepium and the shell sand water gradient,the soil water availability was classified into 6 water grades.The RWC range for maintaining strong photosynthesis and high WUE in P.sepium was 63.22-69.98%.(3)Gas exchange in P.sepium was inhibited under drought and waterlogging stresses.Under these conditions,the photosynthetic electron transport chain was blocked,and the dissipation of light energy as heat increased,which ultimately led to a decline in photo synthetic productivity;moreover,transpiration and dissipation were aggravated,and water transmission and utilization processes in P.sepium were hindered.A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P.sepium was observed;this mechanism allowed P.sepium growing in shell sand to be highly adaptable to water stress.
基金Under the auspices of National Natural Science Foundation of China(No.41371538)Independent Project of State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences(No.SKLURE2008-1-02)
文摘River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help in developing an effective catchment management strategy to protect precious water resources. This study analyzed river water quality, patterns of terrestrial and riparian ecosystems, intensity of agricultural activities, industrial structure, and spatial distribution of pollutant emissions in the Haihe River Basin in China for the year of 2010, identifying the variables that have the greatest impact on river water quality. The area percentage of farmland in study area, the percentage of natural vegetation cover in the 1000-m riparian zone, rural population density, industrial Gross Domestic Product(GDP)/km^2, and industrial amino nitrogen emissions were all significantly correlated with river water quality(P < 0.05). Farming had the largest impact on river water quality, explaining 43.0% of the water quality variance, followed by the coverage of natural vegetation in the 1000-m riparian zone, which explained 36.2% of the water quality variance. Industrial amino nitrogen emissions intensity and rural population density explained 31.6% and 31.4% of the water quality variance, respectively, while industrial GDP/km^2 explained 26.6%. Together, these five indicators explained 67.3% of the total variance in water quality. Consequently, water environmental management of the Haihe River Basin should focus on adjusting agricultural activities, conserving riparian vegetation, and reducing industrial pollutant emissions by optimizing industrial structure. The results demonstrate how human activities drive the spatial pattern changes of river water quality, and they can provide reference for developing land use guidelines and for prioritizing management practices to maintain stream water quality in a large river basin.
基金This research was supported by grants from Chinese National Science Foundation (50478086). The 10th Five-year Key Programs for Science and Technology Development of China (2002AA601120).
文摘Objective To analyze the structure of bacteria in drinking water by molecular biological techniques, Methods DNA of bacteria in drinking water was directly extracted without culture. 16S ribosomal DNA fragments, including V-6, -7, and -8 regions, were amplified with universal primers (EUBf933CJC and EUBr1387) and analyzed by DGGE. Results DGGE indicated that amplification products could be separated, The results showed that DGGE could be used in the separation of different microbial 16SrRNA genes extracted from drinkng water. Though there were special bacteria in different water samples, the predominant bacteria were essentially the same. Three sequences of the reclaimed specific bands were obtained, and phylogenetic tree of these bands was made. Conclusion Bacterial diversity in drinking water is identified by molecular biological techniques.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61871234 and 11847062)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180755)
文摘It is difficult to obtain a clear image in underwater turbulence environment with classical imaging methods due to the absorption, scattering, and underwater turbulence on the propagation beam.However, ghost imaging(GI), a nonlocally imaging technique, has shown the turbulence-free ability in atmospheric turbulence by exploiting the second-order correlation between the signal beam and the reference beam.In this paper, we experimentally investigate the imaging quality of GI affected by the underwater environment, where the underwater environment is simulated by a 1 m×0.4 m×0.4 m tank with distilled water.The water temperature is controlled by a heater inside the tank, and a temperature gradient is obtained by putting the heater at different positions of the tank.The water vibration is produced by a heavy force, and the turbid medium is obtained by dissolving very small specks of CaCO3 in the water.A set of Hadamard speckle pattern pairs are generated and modulated on the incident beam, and then the beam illuminates on an unknown object after passing through the simulated underwater environment.With the second-order correlations, the image is reconstructed under different temperature gradients, water vibration, and turbid medium ratios.The results show that GI has the turbulence-free ability under lower temperature gradient, water vibration, and turbid media.The structural similarity image measurement(SSIM)values of the reconstructed images only start to decrease when the temperature gradient is greater than 4.0℃.The same temperature gradient produced at the different positions has a little effect on the quality of the underwater GI.
文摘An analogy between water flux and the field of temperature gradient in a column of wood fuel chips was discovered by these experiments.The heat-mass transfer coeffieient was deter-mined by least squares method.An equation relating water flux and tempetature gradient was devel-opcd and it was demonstrated that the tempeature gradient was the main driving force for watertransport.The meehanism was evaporation-condensation of water vaor through natural convcctionin air phase.The study gives a theoretical exlanation for analyzing the problem of water transport inwood particle material.