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1.
淮河流域焦岗湖水质参数时空变化及影响因素 总被引：3，自引：1，他引：2
焦岗湖是淮河左岸一个天然湖泊,集防洪、灌溉、养殖、旅游等多种功能于一体.利用焦岗湖4个季节水质监测数据,运用Kriging方法,分析焦岗湖水质参数的时空变化及影响因素.结果表明:由于受水文季节变化过程及人类活动等综合影响,焦岗湖水质参数在时间及空间上均存在一定差异.从时间变化来看,夏季透明度较低、秋季较高;溶解氧浓度在春、冬季显著高于夏、秋季;总氮、总磷浓度与高锰酸盐指数均表现为夏季最高、秋季最低.从空间变化来看,4个季节的透明度空间差异较为显著;溶解氧浓度在春、冬季空间分布较为均匀,夏季呈现中心高周围低的变化趋势,秋季则表现为西高东低;总磷浓度春季分布较为均匀,夏、秋及冬季则呈西高东低之势;高锰酸盐指数在春、秋季节呈现东高西低之势,夏季高浓度主要集中在湖区北部,冬季浓度变化不大. 相似文献
2.
Spatial and temporal distributions of the trends of extreme precipitation indices were analysed between 1986 and 2005, over the Iberian Peninsula (IP). The knowledge of the patterns of extreme precipitation is important for impacts assessment, development of adaptation and mitigation strategies. As such, there is a growing need for a more detailed knowledge of precipitation climate change.This analysis was performed for Portuguese and Spanish observational datasets and results performed by the Weather Research and Forecast (WRF) model forced by the ERA-Interim reanalysis. Extreme precipitation indices recommended by the Expert Team for Climate Change Detection Monitoring and Indices were computed, by year and season. Then, annual and seasonal trends of the indices were estimated by Theil-Sen method and their significance was tested by the Mann-Kendal test. Additionally, a second simulation forced by the Max Planck Institute Earth System Model (MPI-ESM), was considered. This second modelling configuration was created in order to assess its performance when simulating extremes of precipitation.The annual trends estimated for the 1986–2005, from the observational datasets and from the ERA-driven simulation reveal: 1) negative statistically significant trends of the CWD index in the Galicia and in the centre of the IP; 2) positive statistically significant trends of the CDD index over the south of the IP and negative statistically significant trends in Galicia, north and centre of Portugal; 3) positive statistically significant trends of the R75p index in some regions of the north of the IP; 4) positive statistically significant trends in the R95pTOT index in the Central Mountains Chain, Leon Mountains and in the north of Portugal.Seasonally, negative statistically significant trends of the CWD index were found in Galicia, in winter and in the south of the IP, in summer. Positive statistically significant trends of the CWD index were identified in the Leon Mountains, in spring, and in Galicia, in autumn. For the CDD index, negative statistically significant trends were seen in Valencia, in the spring, and, in Galicia and Portugal (north and centre), in summer. Positive statistically significant trends of the CDD index were found: in the east of the IP, in the winter; in the Cantabrian Mountain, in the spring; and, in the south of the IP, in summer. Regarding to the R75p index, negative statistically significant trends were found in Galicia, in winter and positive statistically significant trends in the north of Portugal, in spring and in the Central Mountains Chain and north of Portugal, in autumn. For the R95pTOT index, negative statistically significant trends were found over the Sierra Cuenca and Sierra Cazorla, in winter and positive statistically significant trends were found over the Sierra Cebollera, in winter and in Castile-la Mancha region, in spring.The results of the annual and seasonal trends of the extreme precipitation indices performed for observational datasets and the simulation forced by ERA-Interim, are similar. The results obtained for the simulation forced by MPI-ESM are not satisfactory, and can be a source of criticism for the use of simulation forced by MPI-ESM in this type of climate change studies. Even for the relatively short period used, the WRF model, when properly forced is a useful tool due to the similar results of Portuguese and Spanish observational datasets and the simulation forced by ERA-Interim. 相似文献
3.
大姚地热动态特征分析 总被引：3，自引：1，他引：3
通过大姚高精度水温观测井水地质、井孔条件的分析，震例观测资料、实验观测数据的处理，以及井水水质分析结果，表明大姚水温周期性变化的突出位置是井深75m左右，根本原因是该地层石膏脉稳定释热，含水层热水与井内冷水混合过程中，在通道内形成钙盐类沉淀物（如CaSO4CaCO3），堵塞对流通道，含水层内外压差突破被阻塞通道，热水反复侵入井内，便形成水温周期性变化。地震的孕育、发生和调整过程，由于应力场作用，产生附加地热场，水温基值发生变化，周期畸变或消失，这种附加地热动态是可以恢复的。所以认为大姚地热动态是井区特殊地层地热信息的反映。 相似文献
4.
大通湖及东洞庭湖区生物体重金属的水平及其生态评价 总被引：4，自引：0，他引：4
于2005年11月采集了大通湖及东洞庭湖区湖水和水生生物样品,并测定了水和水生生物样品中重金属(Cd、Pb、Hg、As)的含量,并对湖区生物体重金属进行了污染评价.研究结果表明,大通湖及东洞庭湖区湖水中重金属含量较小,绝大部分采样点水质都属于国家Ⅰ类水标准;水生生物体内CD、Pb含量为虾＞螺＞鱼,Hg的含量为鱼＞螺＞虾,As的含量为螺＞虾＞鱼;而鱼类重金属含量则为底栖鱼类＞中上层鱼类,肉食性鱼类＞植食性鱼类.大通湖及东洞庭湖区生物体中CD、Pb的污染指数为虾＞螺＞鱼,Hg的污染指数则为鱼＞螺＞虾,As的污染指数则为螺＞虾＞鱼. 相似文献
5.
A close negative correlation was found to exist between oxygen concentration in winter and the latitude in rivers in the basins
of the Ob and Volga. This can be explained by an increase in the duration of the freeze-up period (during which oxygen is
consumed for oxidation of organic matter (OM) in water and bottom sediments) in the direction from the south to the north,
while the input from oxygen from the atmosphere and photosynthesis is practically zero. No inverse relationship was found
to exist between dissolved oxygen and the latitude, because in rivers of mountain and semimountain types, typical of this
basin, organic matter (OM) does not accumulate in bottom sediments and the conditions of atmospheric circulation are better
than in lowland rivers. The magnitude of seasonal variations in oxygen in lowland rivers is greater than in mountain ones
because of an abrupt drop in oxygen concentration in slowly flowing rivers in winter and the saturation of their water by
oxygen from photosynthesis in summer. 相似文献
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8.
Spatial and seasonal patterns of flood change across Brazil 总被引：1，自引：1，他引：0
Brazil has some of the largest rivers in the world and has the second greatest flood loss potential among the emergent countries. Despite that, flood studies in this area are still scarce. In this paper, we used flood seasonality and trend analysis at the annual and seasonal scales in order to describe flood regimes and changes across the whole of Brazil in the period 1976–2015. We identified a strong seasonality of floods and a well-defined spatio-temporal pattern for flood occurrence. There are positive trends in the frequency and magnitude of floods in the North, South and parts of Southeast Brazil; and negative trends in the North-east and the remainder of Southeast Brazil. Trends in the magnitude (frequency) were predominant in the winter (summer). Overall, floods are becoming more frequent and intense in Brazilian regions characterized by wet conditions, and less frequent and intense in drier regions. 相似文献
9.
This paper examines present and future resource utilization in the tidal section of the Georges River in the southern part of Sydney. Over the last 30 years, the physical characteristics of the river have changed as a result of urbanization, changed hydrologic regime and sand dredging. Urbanization has resulted in an increase in population from 190,000 in 1947 to 550,000. This has resulted in an increase in runoff, sediment input to the river and waste disposal. The change in hydrologic regime has resulted in a substantial increase in the magnitude and frequency of flooding which has increased erosion. Sand dredging has increased the channel capacity, enlarged the tidal prism and increased water turbidity. It has also resulted in extensive bank erosion in the upper part of the river and extensive deposition lower down as tailings are deposited. Although most of these changes have resulted in the deterioration of environmental quality, use of the river for recreation and as an urban amenity has increased. 相似文献
10.
The continuous increase in concentration of greenhouse gases in the atmosphere is expected to cool higher levels of the atmosphere. There is some direct and indirect experimental evidence of long-term trends in temperature and other parameters in the mesosphere and lower thermosphere (MLT). Here we look for long-term trends in the annual and semiannual variations of the radio wave absorption in the lower ionosphere, which corresponds to the MLT region heights. Data from central and southeastern Europe are used. A consistent tendency to a positive trend in the amplitude of the semiannual wave appears to be observed. The reality of a similar tendency in the amplitude of the annual wave is questionable in the sense that the trend in the amplitude of the annual wave is probably induced by the trend in the yearly average values of absorption. The phases of both the annual and semiannual waves display a forward tendency, i.e. shift to an earlier time in the year. A tentative interpretation of these results in terms of changes of the seasonal variation of temperature and wind at MLT heights does not contradict the trends observed in those parameters. 相似文献
11.
The Miyun reservoir is an important water supply for Beijing city. The distribution laws of nitrogen in the Miyun reservoir waters and the transportation factors have been systematically analyzed in space and time by using water monitoring data sampled in the high-water and low-flow periods in 2001 and 2002. The nitrogen in east and west reservoir waters is distributed differently in space. It shows the change characteristics in high-water and low-flow periods and is affected by the source of nitrogen, runoff conditions, hydrodynamic conditions, precipitation and the control of bed mud, of which the source of nitrogen controls the change of concentration of nitrogen, the peripheral runoff controls the distribution law of nitrogen, bed mud controls the vertical distribution of nitrogen, and the contents of nitrogen and its change in the surrounding environment directly cause the change of concentration of total nitrogen in the waters. The improvement and protection of the waters in the Miyun reservoir basically rests with the amelioration of the peripheral environment. 相似文献
12.
Regime observations 017 the zoobenthos state in the Balagansk transect in 1971, 1972 and in the Odissa bay in 1987-1993 of the Bratsk Reservoir were conducted.In 1991-1993 there is a change in the zoobenthos structure of the Bratsk Reservoir. In the depth zone of 0-5 m in the Balagansk transect in 1971-1972 the bottom community was considered as Gammaridae-Chiro-nomodae, in 1991 as Gammaridae-Ephemeroptera in 1992-1993 as Chironomidae-Ephemeroptera-Gammaridae. As compared with 1968-1972 the importance of Gammaridae decreased and the role of Ephemeroptera increased in the zoobenthos structure in 1991-1993.Changes were noted in the species composition of the Ologochaeta fauna and increase of the role of Oligochaeta in the zoobenthos in 1991-1993 as compared with 1965-1972.During all studies Chironomidae played a significant role in the zoobenthos. Since 1989 Paratanytarsus baialensis, bailialian endemic, has occurred in the Chironomidae fauna.The comparison of zoobenthos has shown that aver-age number and biomass of bortom invertebrates by 3-6 times and species diversity by 2.25 are higher^ in the Odissa bay than in the Balagansk transect. 相似文献
13.
回顾总结了2019年地震活动,从全球到局部,呈现了全球、中国和四川的地震活动概况;分析了全球、中国和四川地震活动的特征;记叙了2019年四川区域内发生的突出地震事件;追踪了2008年汶川8.0级地震以来四川区域内发生的3次7级以上地震的余震活动。结果显示:2019年全球M≥7.0地震活动特征呈现低频次、低强度,主体地区为环太平洋地震带;我国周边未发生M≥7.0地震,表明影响我国地震活动的动力边界地震活动偏弱,我国大陆和邻区地震活动表现出频次低、强度弱的特点,我国大陆地震分布总体显示强度西强东弱,区域上显示M≥5级地震分布于青藏地块、西域地块和华南地块;台湾及其附近海域地震活动频次和强度也偏低;四川区域地震活动强度呈现东强西弱特征,四川区域突出地震事件全部集中在川东南区域;2008年以来,四川区域的汶川8.0级、芦山7.0级和九寨沟7.0级地震的余震持续活动。 相似文献
14.
G. A. Zherebtsov V. A. Kovalenko S. I. Molodykh O. A. Rubtsova 《Geomagnetism and Aeronomy》2009,49(8):1264-1270
The scenario of climatic changes in the 20th century has been presented in the scope of the developed model concerning the
effect of solar activity on the parameters of the climatic system governing the energy flux, outgoing from the Earth into
space in the high-latitude regions. The regularities of changes in the circulation in the atmosphere and ocean are discussed.
Specific attention is paid to the causes of a “cold snap” in 1940–1976 in the Northern Hemisphere and the nature of an anomalous
increase in the heat content in the Earth climatic system (ocean) in 1969–1980. It has been indicated that these phenomena
result from changes in the circulation in the atmosphere and ocean (specifically, a change in the thermohaline circulation
in the Northern Atlantic), heat exchange between the ocean and the atmosphere and cryosphere. 相似文献
15.
A. V. Klyuchevskii 《Izvestiya Physics of the Solid Earth》2010,46(4):306-316
Variations in annual numbers of earthquakes (the earthquake occurrence rate) that hit the Baikal region and Mongolia during
the period from 1964 through 2001 are studied in this work. Correlation analysis of the different-length series of annual
numbers N of earthquakes of representative energy classes makes it possible to reveal the effects of synchronous changes in the earthquake
occurrence rate in seven regions and eleven areas in the Mongolia-Baikal region, located far apart. The analysis of the shock
occurrence rate revealed episodes of short-period synchronization of seismic processes in the Mongolia-Baikal region at the
end of the 1960s, early in the 1980s, and in the middle of the 1990s. The episode of synchronization in the earthquake occurrence
rate in the early 1980s is observed in all the territories under study, but the episode at the end of the 1960s is less distinctly
seen in Mongolia and is revealed mainly in the data series with a length of three years. The synchronization in the seismicity
in Mongolia and in the southern PreBaikal region in 1995 requires further investigations, involving the dynamic parameters
of the earthquake sources. The observed synchronism in the annual number of earthquakes indicates that the seismic processes
become active nearly simultaneously over the huge territory of the Mongolia-Baikal region and produce a short-term coherent
change in the shock occurrence rate in the spatial-temporal distribution of the seismicity. The observed spatial and temporal
correlation in the seismicity is a sign of the seismogenic link between the Baikal region and Mongolia. 相似文献
16.
三峡水库长江干流及其支流枯水期浮游植物多样性与水质 总被引：7，自引：0，他引：7
2010年4月对长江干流和26条支流未淹没区与回水区的浮游植物进行调查.结果表明,硅藻、绿藻和蓝藻共占浮游植物种类的93.33%～93.88%.干流优势种类有1门1种、未淹没区有3门6种、回水区有5门6种,出现率分别为15.38%、9.23%和25.00%.回水区现存量平均值最高、未淹没区其次、干流最低.现存量组成在干流、未淹没区和回水区之间有差异,绿藻所占比例干流最高,硅藻所占比例未淹没区最高,隐藻、蓝藻和甲藻所占比例均在回水区最高.Shannon-Wiener多样性指数(H’)和Pielou均匀性指数(J),未淹没区最高、干流次之、回水区最低.17条支流回水区H’和8条支流回水区J均低于未淹没区.水质评价显示,轻或无污染断面(采样点)的比例,干流为76.92%,未淹没区为84.62%,回水区为47.06%.19条(73.08%)支流回水区出现中污染或重污染,7条(26.92%)支流未淹没区出现中污染或重污染.三峡工程蓄水对回水区浮游植物与水质影响比长江干流更大. 相似文献
17.
《Marine pollution bulletin》1987,18(4):164-169
Tissue distributions of heavy metals were investigated in the Weddell seal collected around Syowa Station, Antarctica. Generally, the metal concentrations were high in liver and kidney and low in brain, blubber and skin. Fe in blood and spleen, Zn in bone, and Mn and Cd in pancreas and gastrointestinal organs were also relatively high. Wide variations of the metal concentrations in different bones were also observed. The concentrations of Fe and Cd were positively correlated with moisture content of the bones, while those of Mn and Zn increased with increase of Ca content in the bone. Majority of the metal burden in the body existed in muscle and liver. A relatively high burden of Cd was in the kidney. Based upon these results, the suitability of the tissues of a seal for ecological and toxicological comparisons is discussed. 相似文献
18.
Heavy metal concentrations in the tissues of marine turtles are presented. The most frequently monitored elements are mercury, cadmium and lead; and the tissues mainly analysed in nearly all the stranded individuals are muscle, liver and kidney. The highest mercury and cadmium levels were found in liver and kidney respectively; the majority of the lead burden existed in bones and carapace, while arsenic was present mainly in muscle tissue. Mercury occurred quite completely as methylmercury in muscle, whereas in liver the main form was the inorganic one. Arsenic was exclusively present in the metallorganic form either in muscle tissue or in liver. Metals in the eggs were mainly present in the yolk. Significantly higher concentration of mercury, copper, zinc and iron were found in yolk than albumen, while shell contained highest levels of manganese and copper. The load of trace metals in these animals strictly correlated with the species seems to depend on their different food behaviour. 相似文献
19.
富营养化湖泊围隔中重建水生植被及其生态效应 总被引：1，自引：0，他引：1
水体富营养化导致水生植被衰退、蓝藻水华暴发、水质恶化和水生生态系统崩溃.恢复水生植被被认为是改善受损水体水质和提高其生态系统稳定性的重要手段.本研究通过构建大型围隔,根据水生植物的耐污程度及其对水质和底质等条件的需求,选取几种适宜的水生植物在围隔内进行移栽与群落构建,并以不移栽水生植物的围隔和围隔外水体作为对照.实验期间(2011年4月至2012年6月),围隔内移栽的几种水生植物全部存活,并建立了相对稳定的群落.同时还跟踪监测了3个处理组的水质情况,结果显示,移栽水生植物的围隔内水质明显优于围隔外,与未移栽水生植物围隔相比,也有很大程度的改善,其中移栽水生植物围隔内水体的总氮、铵态氮、总磷、水下消光系数相比于围隔外水体分别低30.55%、44.09%、36.04%和42.13%,相比于未移栽水生植物围隔内水体分别低5.96%、13.40%、6.70%和7.60%,透明度分别比围隔外水体和未移栽水生植物围隔水体高74.59%和8.70%,浮游植物生物量也大大低于围隔外,而浮游动物生物量却明显高于后者.此外,实验后移栽水生植物围隔内沉积物氮、磷含量及其间隙水总氮、总磷、铵态氮浓度明显低于围隔外和未移栽水生植物围隔.研究表明,在富营养化浅水湖泊中通过建立围隔进行合理的群落配置,进而逐步恢复水生植物是完全可行的,而水生植物恢复后加强对其管理和维护至关重要. 相似文献
20.
微生物是湖泊生态系统重要的有机组分。了解不同时期青藏高原湖泊细菌群落特征、环境驱动因子及其群落构建过程的差异,对高原湖泊水生态管理具有重要的指导意义。分别于2020年6和12月采集青藏高原东北部5个湖泊水样,基于高通量测序技术、统计分析和模型分析,解析高原湖泊群在非冰封期和冰封期细菌群落结构、环境驱动因子和中性过程、确定性过程以及随机性过程在细菌群落构建过程的贡献。结果表明：（1）非冰封期湖泊细菌群落的Chao1丰度指数、Simpson和Shannon多样性指数低于冰封期,Spearman相关性分析结果表明非冰封期细菌群落的Chao1丰度指数和多样性指数与水温和海拔显著相关,而冰封期细菌群落的Chao1指数和多样性指数与总氮显著相关;（2）水体细菌群落的优势门均为变形菌门（Proteobacteria）,非冰封期细菌中拟杆菌门（Bacteroidetes）、放线菌门（Actinobacteria）和厚壁菌门（Firmicutes）的平均相对丰度明显高于冰封期。另外,主坐标分析和相似性分析结果表明非冰封期和冰封期的细菌群落组成差异极显著;（3）冗余分析结果表明不同时期湖泊群细菌群落结构的... 相似文献