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991.
The littoral zone in the Three Gorges Reservoir, China: challenges and opportunities 总被引:3,自引:0,他引:3
Xing-zhong Yuan Yue-wei Zhang Hong Liu Sen Xiong Bo Li Wei Deng 《Environmental science and pollution research international》2013,20(10):7092-7102
For flood control purpose, the water level of the Three Gorges Reservoir (TGR) varies significantly. The annual reservoir surface elevation amplitude is about 30 m behind the dam. Filling of the reservoir has created about 349 km2 of newly flooded riparian zone. The average flooding period lasts for more than 6 months, from mid-October to late April. The dam and its associated reservoir provide flood control, power generation, and navigation, but there are also many environmental challenges. The littoral zone is the important part of the TGR, once its eco-health and stability are damaged,which will directly endanger the ecological safety of the whole reservoir area and even the Yangtze River Basin. So, understanding the great ecological opportunities which are hidden in littoral zone of TGR (LZTGR) and putting forward approaches to solve the environmental problems are very important. LZTGR involves a wide field of problems, such as the landslides, potential water pollution, soil erosion, biodiversity loss, land cover changes, and other issues. The Three Gorges dam (TGD) is a major trigger of environmental change in the Yangtze River. The landslides, water quality, soil erosion, loss of biodiversity, dam operation, and challenge for land use are closely interrelated across spatial and temporal scales. Therefore, the ecological and environmental impacts caused by TGD are necessarily complex and uncertain. LZTGR is not only a great environmental challenge but also an ecological opportunity for us. In fact, LZTGR is an important structural unit of TGR ecosystem and has special ecosystem services function. Vegetation growing in LZTGR is therefore a valuable resource due to accumulation of carbon and nutrients. Everyone thinks that the ecological approach to the problem is needed. If properly designed, dike–pond systems, littoral woods systems, and re-created waterfowl habitats will have the capacity to capture nutrients from uplands and obstruct soil erosion. Ecological engineering approaches can therefore reduce environmental impacts of LZTGR and optimize ecological services. In view of the current situation and existing ecological problems of LZTGR, according to function demands such as environmental purification, biodiversity conservation, and vegetation carbon sink enhancement, we should explore the eco-friendly utilization mode of resources in LZTGR. Ecological engineering approaches might minimize the impacts or optimize the ecological services. Natural regeneration and ecological restoration in LZTGR are valuable for soil erosion decrease, pollutant purification, biodiversity conservation, carbon sink increase, and ecosystem health maintenance in TGR. 相似文献
992.
Study on the spectral and Cu (II) binding characteristics of DOM leached from soils and lake sediments in the Hetao region 总被引:1,自引:0,他引:1
Guo X Jiang J Xi B He X Zhang H Deng Y 《Environmental science and pollution research international》2012,19(6):2079-2087
Introduction
Dissolved organic matter (DOM) is the most active component in environmental system and its chemical and structural characteristics most likely influence its biodegradation. Four surface soil (0?C20?cm) and three core sediment samples (0?C10?cm) were collected from Wuliangsuhai Lake. The objectives of this study were to investigate the spectral properties and humification degree of DOM and to determine and discuss comparatively the complexing capacities and stability constants of DOM by Cu (II) in the Hetao region.Materials and methods
In this study, fluorescence spectra and fluorescence quenching methods were used to evaluate the humification degree of DOM and calculate the complexing capacities and the stability constants between DOM and Cu (II).Results and discussion
Two defined peaks, at wavelengths of 260??300?nm (peak I) and 300??350?nm (peak II), could be identified for soil DOM at a ???? value of 30?nm. In sediment DOM extracts, a third peak (III) was observed near 364?nm. The results show that there is a significant difference in the structure of DOM because of different sources. The humification degree is significantly higher for soil samples than those of sediment samples. The FT-IR spectra of DOM show that structure in sediment DOM is more functional groups than those in soil DOM. DOM has a stronger Cu binding affinity in soils than in sediment in the Hetao region, which may lead to potentially significant influence on the migration and transformation of Cu (II). 相似文献993.
Gu HH Qiu H Tian T Zhan SS Deng TH Chaney RL Wang SZ Tang YT Morel JL Qiu RL 《Chemosphere》2011,83(9):1234-1240
The mechanisms of stabilization by silicon-rich amendments of cadmium, zinc, copper and lead in a multi-metal contaminated acidic soil and the mitigation of metal accumulation in rice were investigated in this study. The results from a pot experiment indicated that the application of fly ash (20 and 40 g kg−1) and steel slag (3 and 6 g kg−1) increased soil pH from 4.0 to 5.0-6.4, decreased the phytoavailability of heavy metals by at least 60%, and further suppressed metal uptake by rice. Diffusion gradient in thin-film measurement showed the heavy metal diffusion fluxes from soil to solution decreased by greater than 84% after remediation. X-ray diffraction analysis indicated the mobile metals were mainly deposited as their silicates, phosphates and hydroxides in amended treatments. Moreover, it was found metal translocation from stem to leaf was dramatically restrained by adding amendments, which might be due to the increase of silicon concentration and co-precipitation with heavy metals in stem. Finally, a field experiment showed the trace element concentrations in polished rice treated with amendments complied with the food safety standards of China. These results demonstrated fly ash and steel slag could be effective in mitigating heavy metal accumulation in rice grown on multi-metal contaminated acidic soils. 相似文献
994.
采用气浮—磁分离工艺处理某石化企业的含油废水,重点考察了磁分离单元的工艺条件对除油率的影响。实验结果表明磁分离单元的最佳工艺条件为:絮凝剂聚合氯化铝加入量25 mg/L,磁种加入量100 mg/L,磁场强度40 mT,搅拌条件为先以150 r/min的转速搅拌2 min,再以50 r/min的转速搅拌5 min。在最佳工艺条件下进行气浮—磁分离工艺除油实验,在进水油质量浓度平均为29.5 mg/L时,气浮单元出水油质量浓度平均为8.5 mg/L,除油率平均为71.1%;磁分离单元出水油质量浓度平均为4.7 mg/L,除油率平均为44.1%;总除油率平均为83.8%。 相似文献
995.
996.
As the backland of the Qinghai-Tibet Plateau, the river source region is highly sensitive to changes in global climate. Air temperature estimation using remote sensing satellite provides a new way of conducting studies in the field of climate change study. A geographically weighted regression model was applied to estimate synchronic air temperature from 2001 to 2015 using Moderate-Resolution Imaging Spectroradiometry (MODIS) data. The results were R2?=?0.913 and RMSE?=?2.47 °C, which confirmed the feasibility of the estimation. The spatial distribution and variation characteristics of the average annual and seasonal air temperature were analyzed. The findings are as follows: (1) the distribution of average annual air temperature has significant terrain characteristics. The reduction in average annual air temperature along the elevation of the region is 0.19 °C/km, whereas the reduction in the average annual air temperature along the latitude is 0.04 °C/degree. (2) The average annual air temperature increase in the region is 0.37 °C/decade. The average air temperature increase could be arranged in the following decreasing order: Yangtze River Basin > Mekong River Basin > Nujiang River Basin > Yarlung Zangbo River Basin > Yellow River Basin. The fastest, namely, Yangtze River Basin, is 0.47 °C/decade. (3) The average air temperature rise in spring, summer, and winter generally increases with higher altitude. The average annual air temperature in different types of lands following a decreasing order is as follows: wetland > construction land > bare land glacier > shrub grassland > arable land > forest land > water body and that of the fastest one, wetland, is 0.13 °C/year. 相似文献
997.
Surface ozone and some meteorological parameters were continuously measured from June 2003 to May 2004 at urban Jinan, China. The levels and variations of surface ozone were studied and the influences of meteorological parameters on ozone were analyzed. Annual and diurnal ozone variation patterns in Jinan both show a typical pattern for polluted urban areas. Daytime ozone concentrations in summer were the highest in the four seasons. However, during nighttime from 2100 to 0600 hours ozone concentrations in spring was higher than that in summer. Daily averaged ozone showed negative correlation with pressure and relative humidity and positive correlation with temperature, total solar radiation, sunshine duration and wind speed during the study period. Further studies show that, solar radiation is a primary influence factor for the daytime variations of ozone concentrations at this site; transport of pollutants by wind could enhance the pollution at this site; precipitation has a significant influence on decreasing surface ozone. A multi-day ozone episode from 16 to 21 June 2003 was observed at this site. Surface meteorological data analysis and backward trajectory computation show that the episode is associated with the influence of typhoon Soudelor, attributing to both local photochemical processes and transport of air pollutants from southeastern coastal region, especially Yangtze River Delta region. 相似文献
998.
Effects of land cover changes induced by large physical disturbances on hydrological responses in Central Taiwan 总被引:1,自引:0,他引:1
Nien Ming Hong Hone-Jay Chu Yu-Pin Lin Dung-Po Deng 《Environmental monitoring and assessment》2010,166(1-4):503-520
This study analyzes the significant impacts of typhoons and earthquakes on land cover change and hydrological response. The occurrence of landslides following typhoons and earthquakes is a major indicator of natural disturbance. The hydrological response of the Chenyulan watershed to land use change was assessed from 1996 to 2005. Land use changes revealed by seven remote images corresponded to typhoons and a catastrophic earthquake in central Taiwan. Hydrological response is discussed as the change in quantities and statistical distributions of hydrological components. The land cover change results indicate that the proportion of landslide relative to total area increased to 6.1% after the Chi-Chi earthquake, representing the largest increase during the study period. The study watershed is dominated by forest land cover. Comparisons of hydrological components reveal that the disturbance significantly affects base flow and direct runoff. The hydrological modeling results demonstrate that the change in forest area correlates with the variation of base flow and direct runoff. Base flow and direct runoff are sensitive to land use in discussions of distinction. The proposed approach quantifies the effect of typhoons and earthquakes on land cover changes. 相似文献
999.
猪场废弃物强制通风静态仓堆肥系统的试验研究 总被引:1,自引:0,他引:1
通过组织5个猪场废弃物堆肥试验,度量温度、表观性状、体积、重量损失、全氮、全磷、大肠杆菌值、蛔虫卵杀灭率和发芽指数等指标,检验了开发的强制通风静态仓堆肥系统的性能.结果表明,除起始含水率为80%试验堆体因起始含水率过高导致发生厌氧反应外,其余4个堆体均实现堆肥无害化、减量化、稳定化和资源化的处理目标;堆肥温度维持50℃以上5~7 d,或55℃以上3 d是大肠杆菌值达到国家粪便无害化卫生标准的必要条件;堆肥过程能有效脱除堆料的生物毒性,后腐熟阶段是必需阶段;氮、磷、钾等主要营养元素在堆肥前后呈现"浓缩效应".因此,堆肥化能提高猪场废弃物肥效和利用价值. 相似文献
1000.