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鄱阳湖河湖转换期间鱼腥藻(Anabaena)的变化 总被引：1，自引：1，他引：0
鄱阳湖作为我国长江目前仅存的两个通江湖泊之一,年内水位变幅巨大.通过在鄱阳湖2013年河湖转换期间(5—11月)对鄱阳湖主航道都昌段进行每月3~4次的高频监测,以考察鄱阳湖水体中鱼腥藻(Anabaena)的动态变化,分析鄱阳湖中鱼腥藻生长并占优势的影响因素.结果表明,蓝藻为鄱阳湖浮游植物的次级优势种,8月蓝藻生物量平均占浮游植物生物量的57%,蓝藻取代硅藻成为暂时的优势种.夏、秋季水华蓝藻以固氮鱼腥藻为主,主要与夏、秋季水温较高以及适宜的营养盐条件等有关.研究期间鄱阳湖水体氮磷比平均在15左右,鱼腥藻能够产生有固氮能力的异形胞,并在水华蓝藻中成为优势种,也反映了鄱阳湖某些湖区存在氮相对缺乏的阶段. 相似文献
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鄱阳湖流域大型湖库水生生态环境变化及驱动力分析——以柘林湖为例 总被引：3，自引：2，他引：1
鄱阳湖流域内湖库资源众多,柘林湖作为鄱阳湖最大的入湖湖库,是鄱阳湖流域内最大的调节湖库,对鄱阳湖入湖径流有一定的影响,在鄱阳湖的入湖流量中占重要地位.本文以鄱阳湖流域内纳入水质良好湖泊的柘林湖为例,通过对柘林湖的形成及湖泊水系生态环境演变进行探讨,分析近30年来该湖水生生态环境的变化及其关键驱动力因子.综合研究表明:柘林湖水生生物多样性有下降趋势,水质有先变差后改善的趋势,其变化的驱动力主要是流域内人口数量增加、城镇化工业化进程加快、入湖污染负荷逐年增长、滨湖区生态安全屏障受人为破坏以及资源开发不合理等.只有处理好"人湖"和谐、"三次飞跃"和"四大转变",并采取科学合理的措施进行集成研究和综合治理,才能行之有效地改善柘林湖水生生态环境,并发挥其应有的生态效应,从而保障鄱阳湖入湖"一湖清水". 相似文献
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鄱阳湖退田还湖及其对洪水的影响 总被引：9，自引：0，他引：9
在详细分析鄱阳湖退田还湖现状基础上,建立了鄱阳湖退田还湖洪水位效应计算模型,估计退田还湖对典型年洪水位的效应.并对退田还湖对年最高水位频率的影响进行了预测.最后,探讨了退田还湖圩区适宜管理模式和退田还湖对湖泊环境的影响. 相似文献
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长江江豚(Neophocaena asiaeorientalis asiaeorientalis)是一种小型齿鲸,仅分布在长江中下游干流和洞庭湖及鄱阳湖中,其种群数量仅约1000头,极度濒危.鄱阳湖是长江江豚最重要的栖息地之一,估算种群数量约450头,是长江江豚最后的避难所.本文系统地总结了鄱阳湖长江江豚种群生态学、保护遗传学和保护生物学的研究进展,着重探讨了各种人类活动对其种群迁移活动的影响,并对鄱阳湖长江江豚种群面临的威胁、保护对策和未来研究方向等进行了总结和展望,以期为今后的保护工作提供借鉴. 相似文献
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于2014年4、7和10月以及2015年1月(分别代表春、夏、秋和冬季)对鄱阳湖13个常规监测点表层水体中氧化亚氮(N_2O)浓度进行测定,并选择合适的模型估算其释放量.结果表明,鄱阳湖全年N_2O平均浓度为32.57±17.35 nmol/L,总体处于过饱和状态,平均饱和度为256.83%±129.05%.鄱阳湖N_2O年平均交换通量为0.83±0.69μmol/(m2·h).鄱阳湖水体N_2O季节性释放规律为春季最高,平均交换通量为1.71μmol/(m2·h),其次是夏季和冬季,秋季最低.从空间上来看,春季北部湖区交换通量显著高于南部湖区.相关性分析表明,铵态氮浓度是影响夏季和冬季鄱阳湖水体N_2O产生的主要因素.结合水域面积初步估算出全年释放N_2O约1.29×107mol,其中春季和夏季是鄱阳湖水体N_2O释放的高峰期,总释放量约占全年的80.40%.全年通过N_2O输出氮素约为361.93 t,对鄱阳湖流域内N_2O分布及质量平衡具有一定影响. 相似文献
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鄱阳湖水位变化规律的研究 总被引：15，自引：5，他引：15
根据都昌水位站１９５３￣１９９２年水位资料，对鄱阳湖水位的基本特征、退水过程及演变趋势进行了统计分析，在此基础上指出鄱阳湖开发利用中面临的主要问题和水位变化对鄱阳湖生态环境可能造成的影响。 相似文献
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In this paper, the changes in sediment transport over 51 years from 1955 to 2006 in the Kuye River in the Loess Plateau in China are assessed. Key factors affecting sediment yield and sediment transport, such as precipitation depth, discharge, and human activities are studied. To investigate the changes in sediment yield in this watershed, a trend analysis on sediment concentration, precipitation depth, and discharge is conducted. Precipitation depths at 2 Climate Stations （CSs）, as well as discharge and sediment transport at 3 Gauging Stations （GSs） are used to assess the features of sediment transport in the Kuye River. The rtmoff modulus （defined as the annual average discharge per unit area, L/（s·km^2）） and the sediment transport modulus （defined as the annual suspended sediment transport per unit area, t/（yr km^2）） are introduced in this study to assess the changes in runoff and sediment yield for this watershed. The results show that the highest average monthly discharge during the study period in the Kuye River is 66.23 m^3/s in August with an average monthly sediment concentration of 88.9 kg/m^3. However, the highest average monthly sediment concentration during the study period in the Kuye River is 125.34 kg/m^3 and occurs in July, which has an average discharge of 42.6 m^3/s that is much less than the average monthly discharge in August. It is found that both the runoff modulus and sediment transport modulus at Wenjiachuan GS on the Kuye River has a clear downward trend. During the summer season from July to August, the sediment transport modulus at Wenjiachuan GS is much higher than those at Toudaoguai and Longmen GSs on the Yellow River. The easily erodible loess in the Kuye River watershed and the sparse vegetation are responsible for the extremely high sediment yield from the Kuye River watershed. The analyses of the grain size distribution of suspended load in the Kuye River are presented. The average monthly median grain size of suspended load in the Kuye River is largest in February and then decreases until June. In July, the average monthly median grain size of suspended load approaches another peak and decreases until September. Then, the median grain size of suspended load starts to increase until February of the following year. However, the average monthly median grain size of suspended load in the Yellow River at Toudaoguai and Longmen GSs is the smallest between early summer and late fall The median grain size in the Yellow River starts to increase in November and approaches the largest size in January. 相似文献
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Observations of trace gases (SO2, NH3, NO2 and O3) were made during the period 1981 to 1984 at 6 different locations representative of urban industrial, urban, nonurban, thermal power plant and marine environment. Diurnal variations of the trace gases were studied in an urban environment. Except in the urban industrial environment, the concentration of NH3 was found in the range of background values. Also, the average concentrations of NO2 and O3 at the different environments were in the order of background values. However, the concentrations of SO2 were substantially higher by about 7 times, in urban industrial and thermal power plant environments. The diurnal variations of SO2, NH3 and NO2 showed anitphase relationship with surface temperature at the urban environment station which is relatively free of industrial pollution. Discussion is centred on trace gas variations in different environments in India together with the values reported for various countries in the world. 相似文献
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The aim of this study is to estimate likely changes in flood indices under a future climate and to assess the uncertainty in these estimates for selected catchments in Poland. Precipitation and temperature time series from climate simulations from the EURO-CORDEX initiative for the periods 1971–2000, 2021–2050 and 2071–2100 following the RCP4.5 and RCP8.5 emission scenarios have been used to produce hydrological simulations based on the HBV hydrological model. As the climate model outputs for Poland are highly biased, post processing in the form of bias correction was first performed so that the climate time series could be applied in hydrological simulations at a catchment-scale. The results indicate that bias correction significantly improves flow simulations and estimated flood indices based on comparisons with simulations from observed climate data for the control period. The estimated changes in the mean annual flood and in flood quantiles under a future climate indicate a large spread in the estimates both within and between the catchments. An ANOVA analysis was used to assess the relative contributions of the 2 emission scenarios, the 7 climate models and the 4 bias correction methods to the total spread in the projected changes in extreme river flow indices for each catchment. The analysis indicates that the differences between climate models generally make the largest contribution to the spread in the ensemble of the three factors considered. The results for bias corrected data show small differences between the four bias correction methods considered, and, in contrast with the results for uncorrected simulations, project increases in flood indices for most catchments under a future climate. 相似文献
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Seasonal and annual trends of changes in rainfall, rainy days, heaviest rain and relative humidity have been studied over the last century for nine different river basins in northwest and central India. The majority of river basins have shown increasing trends both in annual rainfall and relative humidity. The magnitude of increased rainfall for considered river basins varied from 2–19% of mean per 100 years. The maximum increase in rainfall is observed in the Indus (lower) followed by the Tapi river basin. Seasonal analysis shows maximum increase in rainfall in the post‐monsoon season followed by the pre‐monsoon season. There were least variations in the monsoon rainfall during the last century and winter rainfall has shown a decreasing trend. Most of the river basins have experienced decreasing trends in annual rainy days with a maximum decrease in the Mahanadi basin. The heaviest rain of the year has increased from 9–27 mm per 100 years over different river basins with a maximum of 27 mm for the Brahamani and Subaranrekha river basins. A combination of increase in heaviest rainfall and reduction in the number of rainy days suggest the possibility of increasing severity of floods. Such information is useful in the planning, development and management of water resources in the study area. Further, the majority of river basins have also experienced an increasing trend in relative humidity both on seasonal and annual scales. An increase in annual mean relative humidity for six river basins has been found in the range of 1–18% of mean per 100 years, while a decrease for three river basins from ? 1 to ? 13% of mean per 100 years was observed, providing a net increase in the study area by 2·4% of mean per 100 years. It is understood that an increase in areal extent of vegetation cover as well as rainfall over the last century has increased the moisture in the atmosphere through enhanced evapotranspiration, which in turn has increased the relative humidity. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Changes in thermal extremes of the climate of Poland in 1951–2010 are examined. Warm extremes have become more frequent, while cold extremes have become less frequent. In the warming climate of Poland, the increase in the number of extremely warm days in a year and the decrease in the number of extremely cold days in a year have been observed. Also the increase of the maximum number of consecutive hot days in a year and the decrease of the maximum number of consecutive very cold and extremely cold days in a year have been observed. However, the trends are not of ubiquitous statistic significance, as the natural variability is strong. 相似文献
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Ingvar B. Fridleifsson 《Pure and Applied Geophysics》1978,117(1-2):242-252
In an active spreading area like Iceland, where the regional geothermal gradient is in the range 50–150°C/km, it is normally not a problem to find high enough temperature with deep drilling, but the difficulties arise with finding permeable layers at depth within the strata. Various volcanological methods can be applied in the search for aquifers and geothermal reservoir rocks. The flow pattern (as deduced from deuterium studies) indicates that the thermal water flows preferentially along high porosity stratiform horizons and dyke swarms from the recharge areas in the highlands to the hot spring areas in the lowlands. The primary porosity of the volcanic strata is dependent on the chemical composition and the mode of eruption of the volcanic units. Both the reservoir rocks and the flow channels forming the geothermal plumbing system are thought to vary from the Tertiary to the Quaternary provinces due to environmental conditions at the eruptive sites. 相似文献
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Cu concentrations in surface (river and lake) and subsurface waters are determined. The geographic pattern of Cu distribution in natural water is identified. This pattern is controlled by the difference between its concentrations in drained rocks and soils and the geochemical redox conditions of its migration. Territories with low, medium, and elevated Cu concentrations in natural waters are identified. The concentrations of Cu in natural waters of the region are found to be generally lower than the Clarke values. 相似文献