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1.
The changes of NH3-N, NO3-N, NO2-N and TN/TP were studied during growth and non-growth season in 33 subtropical shallow lakes in the middle and lower reaches of the Yangtze River. There were significant positive correlations among all nutrient concentrations, and the correlations were better in growth season than in non-growth season. When TP>0.1 mgL-1, NH3-N increased sharply in non-growth season with increasing TP, and NO3-N increased in growth season but decreased in non-growth season with TP. These might be attributed to lower dissolved oxygen and low temperature in non-growth season of the hypereutrophic lakes, since nitrification is more sensitive to dissolved oxygen and temperature than antinitrification. When 0.1 mgL-1>TP>0.035 mgL-1, TN and all kinds of inorganic nitrogen were lower in growth season than in non-growth season, and phytoplank-ton might be the vital regulating factor. When TP<0.035 mgL-1, inorganic nitrogen concentrations were relatively low and NH3-N, NO2-N had significant correlations with phytoplankton, indicating that NH3-N and NO2-N might be limiting factors to phytoplankton. In addition, TN/TP went down with decline in TP concentration, and TN and inorganic nitrogen concentrations were obviously lower in growth season than in non-growth season, suggesting that decreasing nitrogen (especially NH3-N and NO3-N) was an important reason for the decreasing TN/TP in growth season. The ranges of TN/TP were closely related to trophic level in both growth and non-growth seasons, and it is apparent that in the eutrophic and hypertrophic state the TN/TP ratio was obviously lower in growth season than in non-growth season. The changes of the TN/TP ratio were closely correlated with trophic levels, and both declines of TN in the water column and TP release from the sediment were important factors for the decline of the TN/TP ratio in growth season.  相似文献   

2.
The results of studies of the shear wave attenuation field in source zones of the 2003 Chuya, 1970 Ureg-Nur, 1991 Busingol, 2011 Sayan, and 2011–2012 Tuva earthquakes are presented. Attenuation fields in these source zones include blocks with a high Q-factor and linear weakened zones. The surface ruptures from the mainshocks of the 2003 Chuya and 2011–2012 Tuva earthquakes are located in the zones of strong attenuation. Epicenters of the mainshocks are located where the maximum contrast in attenuation is observed. In the source zones of large earthquakes in the Altai–Sayan region or near them, the zones similar to so-called seimogenic bodies described in the literature are found. These objects tend to linear zones with high attenuation and are characterized by an increased density of deepened earthquakes and also by deformations of near-vertical elongation. The obtained data suggest that the fluid factor could play certain role in the occurrence of large earthquakes in the Altai–Sayan region.  相似文献   

3.
The investigation and continuous monitoring with an innovative iron oxide embedded cellulose acetate membrane (FeO/CAM) on the concentrations of biologically available phosphorus (BAP) were conducted in the Meiliang Bay of the Taihu Lake during summer in 2004. The results showed that the concentrations of dissolved (FeO-DP), particulate (FeO-PP) and total bioavailable phosphorus (FeO-P) had similar horizontal distribution. The BAP concentrations were the highest in those estuaries in the northern bay. With the decrease of the distance to the estuary or long shore, there was little difference between BAP concentrations in an open lake area. During the observation period, algal blooms occurred in most waters of the northern bay, which was reflected from the high concentrations of chlorophyll a (Chl-a). While they were not highest in the estuarine waters of those major rivers, this is the case for the BAP concentrations. The concentrations of Chl-a had a significantly positive correlation with those of bioavailable phosphorus in the open area of the Meiliang Bay. With the sediment resuspension induced by wind and wave, BAP concentrations increased in a short-term, indicating that the riverine P inputs mainly contribute to the concentrations of BAP in the estuarine water while internal P release was the major source of BAP in the open lake area. In the eutrophic shallow lake, the blooms of alga may cause pH increase and further result in internal P release. The above results showed that the new membrane of FeO/CAM can be used to monitor the concentrations of BAP and provide the scientific justifications for the control strategy of the lake eu-trophication.  相似文献   

4.
Introduction The medium of the earth is made up of gas, liquid, and solid. The solid is the main material to form the structure of the earth, so it is very significant to study the solid matter of the earth. Rock, as a solid medium of the earth is a common object studied by geophysicists. The measurement of the comprehensive physical properties of rocks (ZHAO, et al, 1996; GUO, et al, 1989) considered that the minimal cell of rock is the atoms of chemical element, and all sorts of the rock …  相似文献   

5.
1 Introduction Soil and soil-structure systems exhibit complex response patterns during earthquake-induced liquefaction. These patterns depend on geotechnical properties, in-situ stress conditions and interaction with subsurface structural elements. Seismic records of full- scale systems during case histories provide a valuable source of information on the associated response mechanisms. However, the response of these systems is commonly monitored at sparsely distributed locations only, mostly…  相似文献   

6.
RS-monitoring index systems of ecological environment changes at a large scale, based on empirical data and trends in environmental change in Central Asia, are developed using NOAA and MODIS data. Moreover, with the help of mathematical statistics and GIS spatial analysis, the degrees, hazards and distribution extent of various possible ecological problems are discussed, environmental changes in Central Asia in 1990 and 2005 are separately evaluated, and dynamic changes in the environment in Central Asia over a 15-year period are analyzed. The results reveal that during the 15-year period from 1990 to 2005, areas of degenerated vegetation in Kazakhstan, Uzbekistan, Turkmenistan, Kirghizstan and Tadzhikistan were enlarged by 0.069×105 km2, 0.081×105 km2, 0.296×105 km2, 0.022×105 km2 and 0.112×105 km2, respectively. The ecological environment in Central Asia was in the state of significant degeneration and even deterioration. This study proves that NOAA and MODIS data can be used to successfully monitor the environment and provide useful results.  相似文献   

7.
ＣｏｍｐａｒｉｓｏｎａｎｄａｎａｌｙｓｉｓｏｆｔｈｅｓｔｒｅｓｓｆｉｅｌｄｉｎｔｈｅｓｏｕｒｃｅｒｅｇｉｏｎｏｆＴａｎｇｓｈａｎａｎｄＬａｎｃａｎｇｅａｒｔｈｑｕａｋｅｓｅｑｕｅｎｃｅｓＧｕｉ－ＬｉｎｇＤＩＡＯ；（刁桂苓）Ｌｉ－ＭｉｎＹＵ；（于利民）...  相似文献   

8.
Iodine is a trace element playing an important role in vital activities of organisms. It is im-portant for human bodys thyroid gland. Deficient or excessive iodine will not only influence hu-man health but also cause feeblemindedness, so great attention h…  相似文献   

9.
Geology and Exploration of Oil and Gas in the Ordos Basin   总被引：2，自引：0，他引：2  
The Ordos basin is rich in oil and gas resources. The structures in the basin are generally rather gentle. Most of the oil and gas pools already found are belong to the types of lithologic, lithostratigraphic and paleo-geomorphic with thin reservoirs. The geology of oil and gas and the generation and distribution of oil and gas resources in the Ordos basin is analyzed in detail in the paper. It is also pointed out in the paper that what direction should be taken in oil and gas exploration in the basin, and that the important role of the seismic prospecting technologies in the discovery of large oil and gas fields in the basin could not be replaced.  相似文献   

10.
InthecompilationofWorldStressMap,9%ofdatacomesfromovercoringandhydraulicfracturingmeas-urement,23%fromboreholebreakingoff,63%fromearthquakefocalmechanism,and5%fromyounggeo-logicalinvestigation(Zoback,etal,1989).Onlyovercoringandhydraulicfracturingcanprovideboththeorienta-tionandmagnitudeofthehorizontalstress,allothermethodscanonlyprovidetheorientation,butnothemagni-tudeofthestresses.Althoughsomeresearcherstriedtoestimatemagnitudesofstressesinearthquakemechanismresearchbasedonsomeadditionalass…  相似文献   

11.
ＳｔｕｄｙｏｆｔｈｅｉｎｔｅｎｓｉｔｙａｔｔｅｎｕａｔｉｏｎｌａｗｉｎｔｈｅＥａｓｔＣｈｉｎａＰｌａｉｎａｎｄｔｈｅｎｏｒｔｈｗｅｓｔｏｆＣｈｉｎａ郁曙君Ｓｈｕ－ＪｕｎＹＵ（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃ...  相似文献   

12.
The results of processing and analyzing the instrumental observations of the Earth’s magnetic field at the Geophysical Observatory Mikhnevo of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IGD RAS) for 2010–2015 are presented. Quasi-harmonic components with the periods close to the lunar–solar tidal waves are revealed in the spectra of geomagnetic variations over a period of 0.4 to 30 days. The elliptical S1 tidal wave which is detected in the geomagnetic variations has modulations with periods of 1/3, 1/2, and 1 year. The spectra of the geomagnetic variations contain peaks corresponding to the free oscillations of the Earth. The analysis of the time series of the magnetic field for the period of the strong earthquakes in the absence of geomagnetic disturbances revealed the fine structure of the Earth’s fundamental spheroidal mode 0S2, which splits into five singlets. The established features of the spectrum of geomagnetic variations are helping the development of the new method for studying the deep structure of the Earth and the properties of the inner geospheres for estimating the viscosity of the Earth’s outer core and dynamics of the current systems in the outer (liquid) core, as well as for exploring, with the use of empirical data, the general regularities governing the regimes of energy exchange processes in the geospheres.  相似文献   

13.
Soldatova  E. A.  Savichev  O. G.  Zhou  D.  Ivanova  I. S.  Li  J.  Dong  Y.  Sun  Z. 《Water Resources》2022,49(3):483-492
Water Resources - Data of studies of 2013–2019 were used to assess the current environmental-geochemical conditions of surface water and groundwater in the basin of the Ganjiang River, the...  相似文献   

14.
Data of network and expedition measurements and information about water management arrangements were used to study in detail the peculiarities of along-channel and long-term variations in the major characteristics of suspended sediment runoff in the lower reach and the delta of the Kuban River. For characteristics periods, the annual volumes of actual and estimated sediment runoff and the contribution of economic activity in its variations are evaluated and possible changes in sediment runoff characteristics in the XXI century are forecasted. The specific features, values, and causes of sediment runoff transformation in Kuban delta in the past and the present are analyzed; sediment balance in the delta is calculated.  相似文献   

15.
Where the Yellow River flows through the Haiyuan-Tongxin arc-form tectonic region on the northeastern side of the Qinghai-Xizang (Tibet) Plateau, as many as 10～21 basis and erosion terraces have been produced, among which the biggest altitude above river level is 401m and the formation age of the highest terrace is 1.57 Ma B.P. Based on comparative analysis of the Yellow River terraces located separately in the Mijiashan mountain, the Chemuxia gorge, the Heishanxia gorge and the other river terraces in the vast extent of the northern part of China, it has been found that the tectonic processes resulting in the formation of the terrace series is one of multi-gradational features, i.e., a terrace series can include the various terraces produced by tectonic uplifts of different scopes or scales and different ranks. The Yellow River terrace series in the study region can be divided into three grades. Among them, in the first grade there are 6 terraces which were formed separately at the same time in the vast extent of the northern part of China and represent the number and magnitude of uplift of the Qinghai-Xizang Plateau since 1.6 Ma B. P. ; in the second grade there are 5 terraces which were separately and simultaneously developed within the Haiyuan-Tianjingshan tectonic region and represent the number and magnitude of uplift of this tectonic region itself since 1.6Ma B. P.; in the third grade there are 10 terraces which developed on the eastern slope of the Mijiashan mountain and represent the number and amplitude of uplift of the Haiyuan tectonic belt itself since 1.6Ma B.P. Comparison of the terrace ages with loess-paleosoil sequence has also showed that the first grade terraces reflecting the vast scope uplifts of the Qinghai-Xizang Plateau are very comparable with climatic changes and their formation ages all correspond to the interglacial epochs during which paleosoils were formed. This implies that the vast extent tectonic uplifts resulting in river down-cutting are closely related to the warm-humid climatic periods which can also resnit in river downward erosion after strong dry and cold climatic periods, and they have jointly formed the tectonic-climatic cycles. There exists no unanimous and specific relationship between the formation ages of the second and third grade terraces and climatic changes and it is shown that the formation of those terraces was most mainly controlled by tectonic uplifts of the Tianjingshan block and the Haiyuan belt. The river terraces in the study region, therefore, may belong to 2 kinds of formation cause. One is a tectonic-climatic cyclical terrace produced jointly by vast extent tectonic uplifts and climatic changes, and the terraces of this kind are extensively distributed and can be well compared with each other among regions. Another is a pulse-tectonic cyclical terrace produced by local tectonic uplifts as dominant elements, and their distribution is restricted within an active belt and can not be compared with among regions.  相似文献   

16.
Summary We have investigated the influence of heating in the D-layer on the convection dynamics for the Rayleight number Ra=106. Strong heating, which may represent a local small-scale heat transfer in the D-layer, results in an increase of lateral heterogeneities near the upper and lower boundaries, the blob-like structure of upwellings and the stabilization of the convection pattern. The influence of the electromagnetic heating was found to be too weak to produce any substantial effect which is in contrast with the idea of Braginskii and Meitlis [1].Dedicated to the Memory of K. P  相似文献   

17.
The spatial-temporal variations in localization of the sources of earthquakes with H ≥ 14 km are reviewed for the Garm region. The uneven distribution of such earthquakes is related to the block structure: their amount is higher in the weakened zones rather than in blocks. Three weakened zones are characterized by higher activity of deepened seismicity, which varies in time and increases before the earthquakes with K ≥ 12.5. The temporal variations in distribution of earthquake sources with depth allow a suggestion of the relation of the velocity of the Earth’s rotation and activity of deepened seismicity.  相似文献   

18.
The relationships between different manifestations of solar and geomagnetic activity and the structural peculiarities of the dynamics of the pole wobble and irregularities in the Earth??s rotation are studied using singular spectrum analysis. There are two close major peaks and several lower ones in the same frequency range (1.1?C1.3 years) in the Chandler wobble (CW) spectrum. Components in the geomagnetic activity were distinguished in the same frequency band (by the Dst and Ap indices). Six- to seven-year oscillations in the Earth??s rotation rate with a complex dynamics of amplitude variations are shown in variations in geomagnetic activity. It is revealed that secular (decade) variations in the Earth??s rotation rate on average repeat global variations in the secular trend of the Earth??s geomagnetic field with a delay of eight years during the whole observation period.  相似文献   

19.
Due to the complexity of geological background and the adverseness of natural geographical environment in the Qinghai-Tibet Plateau, it is very difficult to carry out petroleum geological study in this region. The Qinghai-Tibet Plateau is the only blank space of petroleum exploration on a large scale. The authors carried out the surface geochemical exploration of oil and gas in the Gangbatong-Ya’anxiang and Dongqiao-Nam Co of the Qinghai-Tibet region. Based on the data of actual detection and experiments in the studied area, the characteristics of concentration and profile distribution of the main geochemical exploration indicators (total adsorbed hydrocarbon, altered carbonate, thermal released mercury, etc.) were discussed. The origin of hydrocarbon was also discussed. Moreover, the oil and gas potential of different sections in the Qiangtang Basin and the Biru Basin were evaluated, which could provide references for the exploration and prediction of oil and gas in this region. The concentrations of total adsorbed hydrocarbons in the Ya’anxiang of Suoxian County-Zadong of Baqing County and the Jiecha-Dangxiong of Anduo County in the Qinghai-Tibet region are high, averaging 312.64 μL·kg?1 and 164.36 μL·kg?1. Their altered carbonate concentrations are relatively low, averaging 0.11% and 0.56%. Their concentrations of thermal released mercury are relatively high, averaging 13.09×10?9 and 1.94×10?9. Geochemical exploration results in fact reflect hydrocarbon information in the underground, which are mainly petroleum associated gas and over-matured cracking gas. The Jiecha-Charenluma and the Xiamaya’ertong-Suoba sections in the Qiangtang Basin are the most favorable ones for oil and gas and the Ekou-Zadong section is relatively favorable one, while the Nam Co and the Zigetangcuo-Dongqiao sections in the Biru Basin are the favorable ones for oil and gas, and the Jiang Co-Nading Co and the Ya’anxiang-Ya’ertong sections are relatively favorable ones.  相似文献   

20.
A stable linear relation between foF2 and W with a correlation coefficient of 0.68–0.96 has been revealed as a result of a joint analysis of the foF2 critical frequencies and the virtual minimal heights (h’F) obtained from the data of vertical sounding (VS) of the ionosphere at Dixon Island auroral station, Wolf numbers (W), and PC geomagnetic index from 1963 to 1986. A significant linear relation exists between foF2 and the PC index with a correlation coefficient of r = 0.18–0.67. The correlation between the PC index and W is low in winter and autumn and is r = 0.50 and 0.74 at a significance level of ss = 0.96–0.99 in spring and summer. When the correlation between PC and foF2 is analyzed, it is necessary to consider the effect of solar activity (SA) on both parameters. The multiple correlation coefficients between these parameters have been calculated with regard to the effect of W. They were R = 0.75−0.98; however, the standardized regression coefficients β W and β PC indicated that W and PC considerably and insignificantly affect multiple correlation with foF2, respectively, and this effect depends on the season and time of day. It has been detected that the cyclic variations in foF2 and h’F are asymmetric. The amplitudes of these parameters in cycle 20 are smaller than in cycle 21.  相似文献   

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