This paper analyzed how nutrient silicon and water temperature influenced the variation of phytoplankton growth and the change of its assemblage structure, and probed the different characteristics of the variation of ...This paper analyzed how nutrient silicon and water temperature influenced the variation of phytoplankton growth and the change of its assemblage structure, and probed the different characteristics of the variation of phytoplankton growth and the different profiles of the change of its assemblage structure influenced by nutrient silicon and water temperature. Taking Jiaozhou Bay for example, this paper showed the process of both the variation of phytoplankton growth and the change of its assemblage structure, unveiled the mechanism of nutrient silicon and water temperature influencing the variation of phytoplankton growth and the change of its assemblage structure, and determined that nutrient silicon and water temperature were the motive power for the healthy running of the marine ecosystem.展开更多
The research selected three typical areas for plant investigation, including upper reaches of Gangnan Reservoir, the area between Gangnan and downstream of Huangbizhuang Reservoir, and Huangbizhuang Reservoir. The res...The research selected three typical areas for plant investigation, including upper reaches of Gangnan Reservoir, the area between Gangnan and downstream of Huangbizhuang Reservoir, and Huangbizhuang Reservoir. The results showed that affected by water, plant species, species diversity and species richness were all decreasing in varying degrees as the distance with watercourse upper reaches was increasing, but the ratio of Anthropochory plants was growing. The research finally proposed countermeasures, including increasing wetland area, constructing forests and artificial water landscape of Hutuo River and reinforcing watercourse compre- hensive management.展开更多
Phytoplankton and environment factors were investigated in 2015 and phytoplankton functional groups were used to understand their temporal and spatial distribution and their driving factors in Wanfeng Reservoir. Seven...Phytoplankton and environment factors were investigated in 2015 and phytoplankton functional groups were used to understand their temporal and spatial distribution and their driving factors in Wanfeng Reservoir. Seventeen functional groups(B, D, E, F, G, J, Lo, MP, P, S1, T, W1, W2, X1, X2, Xph, Y) were identified based on 34 species. The dominant groups were: J/B/P/D in dry season, X1/J/Xph/G/T in normal season and J in flood season. Phytoplankton abundance ranged from 5.33×10~4 cells/L to 3.65×10~7 cells/L, with the highest value occurring in flood season and lowest in dry season. The vertical profi le of dominant groups showed little differentiation except for P, which dominated surface layers over 20 m as a result of mixing water masses and higher transparency during dry season. However, the surface waters presented higher values of phytoplankton abundance than other layers, possibly because of greater irradiance. The significant explaining variables and their ability to describe the spatial distribution of the phytoplankton community in RDA diff ered seasonally as follows: dry season, NH4-N, NO_3-N, NO_2-N, TN:TP ratio and transparency(SD); normal season, temperature(WT), water depth, TN, NH4-N and NO_3-N; flood season, WT, water depth, NO_3-N and NO_2-N. Furthermore, nitrogen, water temperature, SD and water depth were significant variables explaining the variance of phytoplankton communities when datasets included all samples. The results indicated that water physical conditions and hydrology were important in phytoplankton community dynamics, and nitrogen was more important than phosphorus in modifying phytoplankton communities. Seasonal differences in the relationship between the environment and phytoplankton community should be considered in water quality management.展开更多
For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams (1 st-5th) of Ashihe Ri...For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams (1 st-5th) of Ashihe River continuum in Maoershan Experimental Forest of Northeast Forestry University, Sharlgzhi City, Heilongjiang Province, China. The indexes of stream water quality, i.e., the pH, dissolved oxygen(DO), turbidity, temperature, PO43-P, NO3-N and NH4^+-N concentrations, total dissolved inorganic nitrogen (TDIN-N, including concentrations of NO3^+-N and NH4^+-N), and total phosphorus (inorganic and organic phosphorous, TP) were measured and analyzed. The stream order, related environmental settings and land-use type were recorded for each sampling location. The indexes of stream water quality at different locations with different stream orders and land use types were compared by ANOVA analysis. The indexes of stream water quality at different sampling locations were analyzed by Hierarchical cluster analysis. Result showed that water quality had significant difference in different stream orders and land use types; some locations with different stream features (stream order and land use type) were grouped into same clusters, indicating that random disturbances produced the variations in water quality, which made the spatial variances of stream water quality inconsistent with the general rules.展开更多
Via the valuable opportunity of the Three Gorges Reservoir (TGR) 135-m filling in June 2003, the Yangtze discharge and suspended sediment concentration (SSC) entering the estuary during the period from 15 May to 15 Ju...Via the valuable opportunity of the Three Gorges Reservoir (TGR) 135-m filling in June 2003, the Yangtze discharge and suspended sediment concentration (SSC) entering the estuary during the period from 15 May to 15 July 2003 were analyzed to examine the instant effects of the filling on them. The Yangtze discharge and SSC entering the estuary in the periods before, during and after the filling clearly indicated three phases: 1) the pre-storage phase characterized by natural conditions, in which the SSC increased with increasing water discharge; 2) the storage phase, during which the SSC decreased dramatically with decreasing water discharge; and 3) the post-storage phase, during which both the SSC and water discharge remained at relatively low levels first until the end of June, then the SSC increased gradually with increasing water discharge. It seems that the times for the instant effects of the decreasing discharge downstream from the upper Yangtze on the Yangtze discharge and SSC entering the estuary due to the TGR 135-m filling to take place were about 5 d and 1 d respectively, while both were about 18 d for those of the increasing discharge. This probably reflects the buffering and resultantly hysteresis of the 1800-km stretch from the upper Yangtze to the estuary. The results are helpful for scientific and hydrological investigation of the Yangtze mainstream downstream from the TGR Dam and of the estuarine and adjacent coastal waters.展开更多
Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased sea- water silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an impo...Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased sea- water silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considered that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern.展开更多
The transport characters of non-uniform sediment before and after the reservoir operation are compared and analyzed. Field data from the Three Gorges Reservoir (TGR), Danjiangkou, and Sanmenxia reservoir indicate that...The transport characters of non-uniform sediment before and after the reservoir operation are compared and analyzed. Field data from the Three Gorges Reservoir (TGR), Danjiangkou, and Sanmenxia reservoir indicate that the transport character of coarse particle is various in different reaches. Before the reservoir operation, the dramatic decrease of the hydraulic condition in some reaches is the main reason to cause the coarse particle deposited. After the reservoir operation, almost all grain sized sediment may be eroded, when the reach is eroded seriously. However, the transport character of the coarse particle will be consistent with what it was before, when the reach is not eroded seriously. The deposition amount will be less than its pre-dam value, and it will tend to decrease with the time going on. Erosion of fine particle results from its unsaturation. Longdistance erosion downstream from reservoir is caused by shortage of the supply from riverbed, especially the shortage of fine particle.展开更多
The optical properties of a waterbody are subjects of research on limnological hydrooptics. The optical properties of, and parameterization methods for, three impurities in Taihu Lake, namely unpigmented suspensions, ...The optical properties of a waterbody are subjects of research on limnological hydrooptics. The optical properties of, and parameterization methods for, three impurities in Taihu Lake, namely unpigmented suspensions, yellow substance and phytoplankton algae, are analyzed in detail in this paper dealing with the optical types of Taihu Lake waters both in winter and in summer. The results showed that: 1) The optical parameters of suspended particles can be calculated by the application of Mie Theory; 2) The absorption of yellow substance decreases exponentially with increasing wavelength, with the mean value of decreasing rate being about 0.014 nm -1; 3) Taihu Lake waters appeared to be of type PY in winter, with suspended particles and yellow substance being the dominant light absorbers, and type CPY in summer, with suspended particles, yellow substance and phytoplankton algae being the dominant light absorbers; 4) In winter or summer, unpigmented suspension has the main effect on the scattering property of Taihu Lake waters.展开更多
Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative ...Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative and quantitative experimental studies were carried out on inactivation of zooplankton cyclops using oxidants, such as chlorine (Cl2), chlorine dioxide (ClO2), ozone (O3), hydrogen peroxide (H2O2), ozone/hydrogen peroxide (O3/H2O2), chloramines (Cl2-NH3) and potassium permanganate (KM4nO4). The influences of various factors include different oxidant dosages, organic substance contents and pH values. The results showed that currently available oxidants used all might inactivate cyclops in some extent. According to the experimental results, chlorine dioxide, ozone, ozone/hydrogen peroxide and chloramines can be selected as effective oxidants for inactivating cyclops because of their strong inactivation abilities. Then the synergic removal effects on cyclops with ozone, ozone/hydrogen peroxide pre-oxidation followed by conventional water treatment processes were investigated, The results showed that ozone and ozone/hydrogen peroxide pre-oxidation can inactivate cyclops effectively, which then can be removed thoroughly by conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.65 mg/L of ozone and 6 mg/L of hydrogen peroxide, with the inactivation rate being 62% before conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.8 mg/L of ozone, with the inactivation rate being 50% before conventional water treatment processes. For different oxidants, when removal rate was the best, the inactivation rate was not the same. These results may provide reference and model for actual waterworks.展开更多
Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytopla...Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a(Chl-a) levels.The Chl-a growth rates(k) ranged from 0.60-1.67 d-1,while microzooplankton grazed the Chl-a at rates(g) of 0.29-0.62 d-1.The addition of C.sinicus enhanced the Chl-a growth rate(Z) by 0.004-0.037 d-1 ind.-1 L.C.sinicus abundance ranged from 84.1-160.9 ind.m-3,which occupied 90.7%-99.1% of the copepod(>500 μm) population.The in-situ increase in phytoplankton by C.sinicus community was estimated to be 0.000 4-0.005 9 d-1.These results showed that microzooplankton were the main grazers of phytoplankton,while C.sinicus induced a slight increase in the levels of phytoplankton.展开更多
An ecological project called fish biomanipulation, other than the conventional fishery culture technique, was put forward in this paper for the excess propagation control of Cyclops. The control effects on Cyclops of ...An ecological project called fish biomanipulation, other than the conventional fishery culture technique, was put forward in this paper for the excess propagation control of Cyclops. The control effects on Cyclops of four species of fish were investigated experimentally at stocking density of 30 g per cubic meter of water. The experimental results showed that the food habit of the fish had significant influence on the biological control of Cyclops. The propagation of Cyclops could be controlled effectively and also the water quality was improved simultaneously by stocking the filter-feeding fishes, such as silver carp and bighead carp. Whereas, herbivorous Ctenopharyugodon idellus and omnivorous Cyprinus carpio had no obvious biological effects on controlling the growth of Cyclops and restoring water quality. The results further proved that under condition of proper poly-culture density of silver carp and bighead carp, the number of Cyclops might be controlled at very low level and the eutrophication might be abated by removing the nutrients from water body.展开更多
The gleyisation of representative paddy soils in the middle reaches of the Yangtze caver was characterized,taking oxidation-reduction potential(Eh),the amount of active reducing substances and the forms of iron and ma...The gleyisation of representative paddy soils in the middle reaches of the Yangtze caver was characterized,taking oxidation-reduction potential(Eh),the amount of active reducing substances and the forms of iron and manganese as the parameters.The Eh value was linearly related with the logarithm of the amount of active reducing substances, which was contributed by ferrous iron by 83% on an avers.The degree of gleyization of dament horizons was graded as ungleyed,slightly gleyed,mildly gleyed and gleyed.The Eh of the four grades was>500,300-500,100-300 and<100 mV,respectively, and the corresponding amoks of active reducing substances was<1,1-7,7-30 and>30 mmol.kg(-1),respectively.The amount of ferrous iron of the four grades was<0.5,0.5-5,5-25 and > 25 mmol kg-1,respectively.The extent of gleyisation of a soil was classified as upper-gleyed, middle-gleyed and lower-gleyed, depending on whether the depth of the gley horbon was less than 30 cm,30-60 cm or more than 60 cm.展开更多
The Revised Universal Soil Loss Equation (RUSLE) was applied to assess the spatial distribution and dynamic properties of soil loss with geographic information system (GIS) and remote sensing (RS) technologies. ...The Revised Universal Soil Loss Equation (RUSLE) was applied to assess the spatial distribution and dynamic properties of soil loss with geographic information system (GIS) and remote sensing (RS) technologies. To improve the accuracy of soil-erosion estimates, a new C-factor estimation model was developed based on land cover and time series normalized difference vegetation index (NDVI) datasets. The new C-factor was then applied in the RUSLE to integrate rainfall, soil, vegetation, and topography data of different periods, and thus monitor the distribution of soil erosion patterns and their dynamics during a 3o-year period of the upstream watershed of Miynn Reservoir (UWMR), China. The results showed that the new C-factor estimation method, which considers land cover status and dynamics, and explicitly incorporates within-land cover variability, was more rational, quantitative, and reliable. An average annual soil loss in UWMR of 25.68, 21.04, and 16.8o t ha-1 a-1 was estimated for 1990, 2000 and 2010, respectively, corroborated by comparing spatial and temporal variation in sediment yield. Between 2000 and 2010, a 1.38% average annual increase was observed in the area of lands that lost less than 5 t ha-1 a^-1, while during 1990-2000 such lands only increased on average by o.46%. Areas that classified as severe, very severe and extremely severe accounted for 5.68% of the total UWMR in 2010, and primarily occurred in dry areas or grasslands of sloping fields. The reason for the change in rate of soil loss is explained by an increased appreciation of soil conservation by developers and planners. Moreover,we recommend that UWMR watershed adopt further conservation measures such as terraced plowing of dry land, afforestation, or grassland enclosures as part of a concerted effort to reduce on-going soil erosion.展开更多
Mosul dam is the biggest hydraulic structure in Iraq located on the River Tigris 60 km northwest of Mosul city. Its storage capacity is 11. 11 × 109 m3 and it had been in operation since 1986. A physical distorte...Mosul dam is the biggest hydraulic structure in Iraq located on the River Tigris 60 km northwest of Mosul city. Its storage capacity is 11. 11 × 109 m3 and it had been in operation since 1986. A physical distorted model with movable bed having a vertical scale 1: 100 and a horizontal scale 1:1000 was used to conduct the experiments relating the water level at the reservoir and water discharge upstream the reservoir with the bed load transport rate. The model represents the first 15 km of most northern part of Mosul dam reservoir. The construction of the model was based on bathymetric survey conducted in 2009. Twenty-four experiments were executed using four different discharges (0.5, 1.0, 1.5, and 2.0 L/s) which represent the average discharges in the flood period of River Tigris. At each individual discharge six operations were assumed where the reservoir's water level was 305, 307, 309, 310, 312, 315 meters above sea level respectively. In all the experiments conducted, bedload transport was measured in the physical model at section representing the River Tigris 1 km upstream the reservoir. The results showed that the bedload rate was decreasing when the water level within the reservoir was increasing. It was also evident that bedload transport rate dramatically decreased at level 310 meters above sea level onward. This is due to the fact that at this level represent the effect of backwater which was noticeable on the river cross section展开更多
Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of...Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of these factors.By clarifying the mechanisms and processes of the impacts by these factors,we have determined the rising order of the importance as solar light,seawater temperature,and nutrient silicon (Si).Therefore,for human interests in sustaining economic development,the first thing to be considered is the input of nutrient Si into the ocean,followed by seawater temperature change.展开更多
From July 23rd to August 15th, 2001, a field cultivation experiment was carried out to determine the limitation factors of phytoplankton in the Yangtze River estuary and the adjacent areas. The results indicated that ...From July 23rd to August 15th, 2001, a field cultivation experiment was carried out to determine the limitation factors of phytoplankton in the Yangtze River estuary and the adjacent areas. The results indicated that the potential limiting nutrient was phosphorus in the Yangtze River diluted water area, nitrogen in the offshore of the Yangtze River estuary and the conversion of phosphorus to nitrogen in the middle area. Iron and silicon were not the potential limiting factors. If there were some kinds of limiting factors in the water, the growth of phytoplankton would be limited obviously. In case of disappearance of the limiting factor, the phytoplankton would grow fast. When the Noctiluca scintiuans bloom occurred, the phytoplankton biomass level was very low in a short time due to the grazing pressure. When the grazing pressure disappeared, the phytoplankton would grow quickly in abundant nutrients condition.展开更多
文摘This paper analyzed how nutrient silicon and water temperature influenced the variation of phytoplankton growth and the change of its assemblage structure, and probed the different characteristics of the variation of phytoplankton growth and the different profiles of the change of its assemblage structure influenced by nutrient silicon and water temperature. Taking Jiaozhou Bay for example, this paper showed the process of both the variation of phytoplankton growth and the change of its assemblage structure, unveiled the mechanism of nutrient silicon and water temperature influencing the variation of phytoplankton growth and the change of its assemblage structure, and determined that nutrient silicon and water temperature were the motive power for the healthy running of the marine ecosystem.
基金Supported by Hebei Provincial Natural Science Foundation(D2012302007)Science and Technology Project of Hebei Academy of Sciences(14111)~~
文摘The research selected three typical areas for plant investigation, including upper reaches of Gangnan Reservoir, the area between Gangnan and downstream of Huangbizhuang Reservoir, and Huangbizhuang Reservoir. The results showed that affected by water, plant species, species diversity and species richness were all decreasing in varying degrees as the distance with watercourse upper reaches was increasing, but the ratio of Anthropochory plants was growing. The research finally proposed countermeasures, including increasing wetland area, constructing forests and artificial water landscape of Hutuo River and reinforcing watercourse compre- hensive management.
基金Supported by the Department of Science and Technology of Guizhou Province(Nos.[2014]7001,[2015]2001,[2015]10)the Water Resources Department of Guizhou Province(No.KT201401)
文摘Phytoplankton and environment factors were investigated in 2015 and phytoplankton functional groups were used to understand their temporal and spatial distribution and their driving factors in Wanfeng Reservoir. Seventeen functional groups(B, D, E, F, G, J, Lo, MP, P, S1, T, W1, W2, X1, X2, Xph, Y) were identified based on 34 species. The dominant groups were: J/B/P/D in dry season, X1/J/Xph/G/T in normal season and J in flood season. Phytoplankton abundance ranged from 5.33×10~4 cells/L to 3.65×10~7 cells/L, with the highest value occurring in flood season and lowest in dry season. The vertical profi le of dominant groups showed little differentiation except for P, which dominated surface layers over 20 m as a result of mixing water masses and higher transparency during dry season. However, the surface waters presented higher values of phytoplankton abundance than other layers, possibly because of greater irradiance. The significant explaining variables and their ability to describe the spatial distribution of the phytoplankton community in RDA diff ered seasonally as follows: dry season, NH4-N, NO_3-N, NO_2-N, TN:TP ratio and transparency(SD); normal season, temperature(WT), water depth, TN, NH4-N and NO_3-N; flood season, WT, water depth, NO_3-N and NO_2-N. Furthermore, nitrogen, water temperature, SD and water depth were significant variables explaining the variance of phytoplankton communities when datasets included all samples. The results indicated that water physical conditions and hydrology were important in phytoplankton community dynamics, and nitrogen was more important than phosphorus in modifying phytoplankton communities. Seasonal differences in the relationship between the environment and phytoplankton community should be considered in water quality management.
基金This research was supported by a grant of the National Nature Science Foundation of China (No. 30370277).
文摘For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams (1 st-5th) of Ashihe River continuum in Maoershan Experimental Forest of Northeast Forestry University, Sharlgzhi City, Heilongjiang Province, China. The indexes of stream water quality, i.e., the pH, dissolved oxygen(DO), turbidity, temperature, PO43-P, NO3-N and NH4^+-N concentrations, total dissolved inorganic nitrogen (TDIN-N, including concentrations of NO3^+-N and NH4^+-N), and total phosphorus (inorganic and organic phosphorous, TP) were measured and analyzed. The stream order, related environmental settings and land-use type were recorded for each sampling location. The indexes of stream water quality at different locations with different stream orders and land use types were compared by ANOVA analysis. The indexes of stream water quality at different sampling locations were analyzed by Hierarchical cluster analysis. Result showed that water quality had significant difference in different stream orders and land use types; some locations with different stream features (stream order and land use type) were grouped into same clusters, indicating that random disturbances produced the variations in water quality, which made the spatial variances of stream water quality inconsistent with the general rules.
基金supported by the National Basic Research Program of China (2002CB412400)the Natural Science Foundation of Shandong Province (Y2007E14)+1 种基金the Doctoral Fund of Ministry of Education of China (200804231011)the Key Lab of Submarine Geosciences and Prospecting Techniques of the Ministry of Education
文摘Via the valuable opportunity of the Three Gorges Reservoir (TGR) 135-m filling in June 2003, the Yangtze discharge and suspended sediment concentration (SSC) entering the estuary during the period from 15 May to 15 July 2003 were analyzed to examine the instant effects of the filling on them. The Yangtze discharge and SSC entering the estuary in the periods before, during and after the filling clearly indicated three phases: 1) the pre-storage phase characterized by natural conditions, in which the SSC increased with increasing water discharge; 2) the storage phase, during which the SSC decreased dramatically with decreasing water discharge; and 3) the post-storage phase, during which both the SSC and water discharge remained at relatively low levels first until the end of June, then the SSC increased gradually with increasing water discharge. It seems that the times for the instant effects of the decreasing discharge downstream from the upper Yangtze on the Yangtze discharge and SSC entering the estuary due to the TGR 135-m filling to take place were about 5 d and 1 d respectively, while both were about 18 d for those of the increasing discharge. This probably reflects the buffering and resultantly hysteresis of the 1800-km stretch from the upper Yangtze to the estuary. The results are helpful for scientific and hydrological investigation of the Yangtze mainstream downstream from the TGR Dam and of the estuarine and adjacent coastal waters.
基金This study was funded by the key subject development of Shanghai Education Council (04SC12), the Director’s Foundation of the Beihai Monitoring Center and the State Oceanic Administration and Chinese Academy of Science (KZCX 2-207).
文摘Silicon is a necessary nutrient for diatoms, silicon uptake in diatom reproduction decreased sea- water silicon content. This paper clarified the characteristics of silicon transferring in the sea, which plays an important role in phytoplankton growth, zooplankton graze and marine ecosystem. Analysis revealed that silicate is supplied by terrestrial sources, through plankton uptake, death, and eventually deposits to the sea bottom, and cannot diffuse upward. This is a general silicon deficit process. Many global marine waters showed the same silicon transfer route: land→silicon biogeochemical process→sea bottom. River flow brings abundant silicate into marine waters, silicate concentration in the waters decreased in the distance away from the river estuaries. In discussion of silicon characteristics and its transfer route, it was considered that the main factor controlling the mechanism of diatom and non-diatom red tides occurrence is silicon, and the changes in silicon source. Human activities, such as sea-route cutting by building embankment and dam, and silicon supplement by the sea, such as sandstorm, rainstorm and storm tide, have largely impaired the earth ecosystem and hugely threatened the human existence. It is suggested in this paper that man should resume the original face of the Si input into the sea to keep natural ecosystem in sustainable pattern.
基金the National Basic Research Program of China("973" Program, No.2003CB415200)
文摘The transport characters of non-uniform sediment before and after the reservoir operation are compared and analyzed. Field data from the Three Gorges Reservoir (TGR), Danjiangkou, and Sanmenxia reservoir indicate that the transport character of coarse particle is various in different reaches. Before the reservoir operation, the dramatic decrease of the hydraulic condition in some reaches is the main reason to cause the coarse particle deposited. After the reservoir operation, almost all grain sized sediment may be eroded, when the reach is eroded seriously. However, the transport character of the coarse particle will be consistent with what it was before, when the reach is not eroded seriously. The deposition amount will be less than its pre-dam value, and it will tend to decrease with the time going on. Erosion of fine particle results from its unsaturation. Longdistance erosion downstream from reservoir is caused by shortage of the supply from riverbed, especially the shortage of fine particle.
基金SupportedbyJiangsuProvince"3 3 3Project" :StudyonOxygenIsotopicSpatiotemporalDistributionandWaterEnvironmentFeaturesofTaihuLakeWaters alsobytheNSFC (No .40 0 710 19)
文摘The optical properties of a waterbody are subjects of research on limnological hydrooptics. The optical properties of, and parameterization methods for, three impurities in Taihu Lake, namely unpigmented suspensions, yellow substance and phytoplankton algae, are analyzed in detail in this paper dealing with the optical types of Taihu Lake waters both in winter and in summer. The results showed that: 1) The optical parameters of suspended particles can be calculated by the application of Mie Theory; 2) The absorption of yellow substance decreases exponentially with increasing wavelength, with the mean value of decreasing rate being about 0.014 nm -1; 3) Taihu Lake waters appeared to be of type PY in winter, with suspended particles and yellow substance being the dominant light absorbers, and type CPY in summer, with suspended particles, yellow substance and phytoplankton algae being the dominant light absorbers; 4) In winter or summer, unpigmented suspension has the main effect on the scattering property of Taihu Lake waters.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2006AA06Z311)the Postdoctoral Science Foundation of Heilongjiang Province (No. LRB05-164)the Excellent Young Teacher Encouragement Project Foundation of HIT(No. HIT2006), China
文摘Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative and quantitative experimental studies were carried out on inactivation of zooplankton cyclops using oxidants, such as chlorine (Cl2), chlorine dioxide (ClO2), ozone (O3), hydrogen peroxide (H2O2), ozone/hydrogen peroxide (O3/H2O2), chloramines (Cl2-NH3) and potassium permanganate (KM4nO4). The influences of various factors include different oxidant dosages, organic substance contents and pH values. The results showed that currently available oxidants used all might inactivate cyclops in some extent. According to the experimental results, chlorine dioxide, ozone, ozone/hydrogen peroxide and chloramines can be selected as effective oxidants for inactivating cyclops because of their strong inactivation abilities. Then the synergic removal effects on cyclops with ozone, ozone/hydrogen peroxide pre-oxidation followed by conventional water treatment processes were investigated, The results showed that ozone and ozone/hydrogen peroxide pre-oxidation can inactivate cyclops effectively, which then can be removed thoroughly by conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.65 mg/L of ozone and 6 mg/L of hydrogen peroxide, with the inactivation rate being 62% before conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.8 mg/L of ozone, with the inactivation rate being 50% before conventional water treatment processes. For different oxidants, when removal rate was the best, the inactivation rate was not the same. These results may provide reference and model for actual waterworks.
基金Supported by the National Natural Science Foundation of China(No.40876085),the National Natural Science Foundation of China(No.40821004)the National Basic Research Program of China(973 Program)(No.2006CB400604)the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-213-3)
文摘Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a(Chl-a) levels.The Chl-a growth rates(k) ranged from 0.60-1.67 d-1,while microzooplankton grazed the Chl-a at rates(g) of 0.29-0.62 d-1.The addition of C.sinicus enhanced the Chl-a growth rate(Z) by 0.004-0.037 d-1 ind.-1 L.C.sinicus abundance ranged from 84.1-160.9 ind.m-3,which occupied 90.7%-99.1% of the copepod(>500 μm) population.The in-situ increase in phytoplankton by C.sinicus community was estimated to be 0.000 4-0.005 9 d-1.These results showed that microzooplankton were the main grazers of phytoplankton,while C.sinicus induced a slight increase in the levels of phytoplankton.
基金Sponsored by the Hi-Tech Research and Development Program of China (Grant No. 2002AA601140 )the National Science Foundation of Heilongjiang Province (Grant No. QC03C17)the Focal Laboratory Opening Research Program of Beijing and the Scientific Resear
文摘An ecological project called fish biomanipulation, other than the conventional fishery culture technique, was put forward in this paper for the excess propagation control of Cyclops. The control effects on Cyclops of four species of fish were investigated experimentally at stocking density of 30 g per cubic meter of water. The experimental results showed that the food habit of the fish had significant influence on the biological control of Cyclops. The propagation of Cyclops could be controlled effectively and also the water quality was improved simultaneously by stocking the filter-feeding fishes, such as silver carp and bighead carp. Whereas, herbivorous Ctenopharyugodon idellus and omnivorous Cyprinus carpio had no obvious biological effects on controlling the growth of Cyclops and restoring water quality. The results further proved that under condition of proper poly-culture density of silver carp and bighead carp, the number of Cyclops might be controlled at very low level and the eutrophication might be abated by removing the nutrients from water body.
文摘The gleyisation of representative paddy soils in the middle reaches of the Yangtze caver was characterized,taking oxidation-reduction potential(Eh),the amount of active reducing substances and the forms of iron and manganese as the parameters.The Eh value was linearly related with the logarithm of the amount of active reducing substances, which was contributed by ferrous iron by 83% on an avers.The degree of gleyization of dament horizons was graded as ungleyed,slightly gleyed,mildly gleyed and gleyed.The Eh of the four grades was>500,300-500,100-300 and<100 mV,respectively, and the corresponding amoks of active reducing substances was<1,1-7,7-30 and>30 mmol.kg(-1),respectively.The amount of ferrous iron of the four grades was<0.5,0.5-5,5-25 and > 25 mmol kg-1,respectively.The extent of gleyisation of a soil was classified as upper-gleyed, middle-gleyed and lower-gleyed, depending on whether the depth of the gley horbon was less than 30 cm,30-60 cm or more than 60 cm.
基金supported by the National Natural Science Foundation of China (Grant No.41101399)the open fund of State Key Laboratory of Remote Sensing ScienceJointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University,China
文摘The Revised Universal Soil Loss Equation (RUSLE) was applied to assess the spatial distribution and dynamic properties of soil loss with geographic information system (GIS) and remote sensing (RS) technologies. To improve the accuracy of soil-erosion estimates, a new C-factor estimation model was developed based on land cover and time series normalized difference vegetation index (NDVI) datasets. The new C-factor was then applied in the RUSLE to integrate rainfall, soil, vegetation, and topography data of different periods, and thus monitor the distribution of soil erosion patterns and their dynamics during a 3o-year period of the upstream watershed of Miynn Reservoir (UWMR), China. The results showed that the new C-factor estimation method, which considers land cover status and dynamics, and explicitly incorporates within-land cover variability, was more rational, quantitative, and reliable. An average annual soil loss in UWMR of 25.68, 21.04, and 16.8o t ha-1 a-1 was estimated for 1990, 2000 and 2010, respectively, corroborated by comparing spatial and temporal variation in sediment yield. Between 2000 and 2010, a 1.38% average annual increase was observed in the area of lands that lost less than 5 t ha-1 a^-1, while during 1990-2000 such lands only increased on average by o.46%. Areas that classified as severe, very severe and extremely severe accounted for 5.68% of the total UWMR in 2010, and primarily occurred in dry areas or grasslands of sloping fields. The reason for the change in rate of soil loss is explained by an increased appreciation of soil conservation by developers and planners. Moreover,we recommend that UWMR watershed adopt further conservation measures such as terraced plowing of dry land, afforestation, or grassland enclosures as part of a concerted effort to reduce on-going soil erosion.
文摘Mosul dam is the biggest hydraulic structure in Iraq located on the River Tigris 60 km northwest of Mosul city. Its storage capacity is 11. 11 × 109 m3 and it had been in operation since 1986. A physical distorted model with movable bed having a vertical scale 1: 100 and a horizontal scale 1:1000 was used to conduct the experiments relating the water level at the reservoir and water discharge upstream the reservoir with the bed load transport rate. The model represents the first 15 km of most northern part of Mosul dam reservoir. The construction of the model was based on bathymetric survey conducted in 2009. Twenty-four experiments were executed using four different discharges (0.5, 1.0, 1.5, and 2.0 L/s) which represent the average discharges in the flood period of River Tigris. At each individual discharge six operations were assumed where the reservoir's water level was 305, 307, 309, 310, 312, 315 meters above sea level respectively. In all the experiments conducted, bedload transport was measured in the physical model at section representing the River Tigris 1 km upstream the reservoir. The results showed that the bedload rate was decreasing when the water level within the reservoir was increasing. It was also evident that bedload transport rate dramatically decreased at level 310 meters above sea level onward. This is due to the fact that at this level represent the effect of backwater which was noticeable on the river cross section
基金Supported by the Knowledge Innovation Project of Chinese Academy of Sciences (No.KZCX 2-207)Zhejiang Bureau of Science and Technology (No.2007C23075)
文摘Based on research results on the impacts of solar light,seawater temperature,and nutrient available to phytoplankton growth and changes in phytoplankton physiology and assemblage,we discussed the order of influence of these factors.By clarifying the mechanisms and processes of the impacts by these factors,we have determined the rising order of the importance as solar light,seawater temperature,and nutrient silicon (Si).Therefore,for human interests in sustaining economic development,the first thing to be considered is the input of nutrient Si into the ocean,followed by seawater temperature change.
文摘From July 23rd to August 15th, 2001, a field cultivation experiment was carried out to determine the limitation factors of phytoplankton in the Yangtze River estuary and the adjacent areas. The results indicated that the potential limiting nutrient was phosphorus in the Yangtze River diluted water area, nitrogen in the offshore of the Yangtze River estuary and the conversion of phosphorus to nitrogen in the middle area. Iron and silicon were not the potential limiting factors. If there were some kinds of limiting factors in the water, the growth of phytoplankton would be limited obviously. In case of disappearance of the limiting factor, the phytoplankton would grow fast. When the Noctiluca scintiuans bloom occurred, the phytoplankton biomass level was very low in a short time due to the grazing pressure. When the grazing pressure disappeared, the phytoplankton would grow quickly in abundant nutrients condition.