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61.
Jiutan Liu Zongjun Gao Min Wang Yingzhi Li Yuanyuan Ma Mengjie Shi Hongying Zhang 《Environmental Earth Sciences》2018,77(18):646
The valley plain of Lhasa City is located on the Qinghai-Tibetan Plateau, which is one of the most developed and densely populated areas in Tibet. Groundwater is an important water supply source and plays an irreplaceable role in the social and economic development of Lhasa City. This study has investigated the dynamic characteristics of groundwater in the valley plain of Lhasa City through the methods of mathematical statistics and hydrochemical analysis. The results showed that local topography, climate, and urbanization substantially influenced the groundwater dynamics. Under the combined influences from urbanization and climate, the groundwater level decreased over three time periods, but the groundwater-level configuration has not shown significant changes in over 15 years. From 1997 to 2015, the hydrochemical type of groundwater has changed from HCO3–Ca to HCO3·SO4–Ca·Mg and HCO3·SO4–Ca. The concentrations of Cl?, Mg2+, and SO42? in groundwater increased, but the concentrations of other ions were relatively stable. Water–rock interaction was the main mechanism controlling the groundwater chemistry in the study area, and it was mainly associated with the dissolution of silicate, carbonate, and halite. 相似文献
62.
中国北方滨海湿地退化研究综述 总被引:4,自引:0,他引:4
中国北方沿海有入海河口湿地、三角洲湿地、粉砂淤泥质海岸湿地、海湾湿地、砂质海岸湿地、沉积岛屿滩涂湿地和滨海泻湖湿地等类型的滨海湿地约182.33×104hm2。由于受到海岸侵蚀、海面上升、风暴潮、入海河流断流和输沙量减少、气候变化等自然因素和围垦、城市和港口建设、污染、海岸带油气资源开发、在入海河流上中游建设水库拦蓄径流和泥沙等人为因素的影响,中国北方的滨海湿地发生了严重的退化。中国北方滨海湿地的退化表现在物理、化学和生物3个方面。其中物理方面表现为自然湿地面积减小、人工湿地面积增大、湿地景观格局破碎化等,化学方面表现为湿地温室气体排放增加、水体富营养化、潮下带近海湿地赤潮灾害增强、湿地底质和渔获物污染、湿地土壤含盐量变化等,生物方面表现为湿地生物多样性水平下降、自然湿地净初级生产力降低、潮间带滩涂湿地和潮下带近海湿地渔获量减小、自然湿地植被退化演替等。 相似文献
63.
Du Zongjun Li Yun Yu Dehua Wang Xianghong Chen Jixiang P. A. W. Robertson B. Austin Xu Huaishu 《中国海洋大学学报(英文版)》2002,1(1):59-62
From Oct. 1999 to Oct. 2000, the heterotrophic bacterial floras in the industrial marine environment around the Qingdao Power
Plant (QPP) and in the unpolluted marine environments were investigated. The results showed that the numbers of the heterotrophic
bacteria around QPP were much higher than those in unpolluted environments, and the average numbers in QPP Seawater, QPP Sediment,
Unpolluted Seawater and Unpolluted Sediment were 5.4×104cfu(mL)−1, 5.0×105cfug−1, 3.0×102cfu(mL)−1 and 1.3×105cfug−1 respectively. Totally, 118 strains were isolated from QPP and 99 of them were Gram-negative. One hundred and twenty one strains
were isolated from the unpolluted environments and 104 of them were Gram-negative. All the Gram-negative bacteria belonged
to 13 genera. The distribution of the bacteria was varied in different marine environments. The results showed that the unpolluted
marine environments contained much more Vibrio than seawater and sediment around QPP. 相似文献
64.
通过对青岛城区土壤进行调查取样,运用单因子评价和内梅罗指数法对青岛表层土壤8种重金属元素(As,Cd,Cr,Cu,Ni,Hg,Pb和Zn)的测试结果进行评价,查明了土壤环境质量现状及其污染程度:青岛市土壤环境质量总体较高,绝大部分地区土壤环境保持在清洁水平;污染区域以孤岛状零星分布于青岛市内,区内胶州湾入海口污染指数偏高,很可能是由于河流上游污水排放导致的。通过对未来20年城区土壤在大气降尘影响下重金属Cd,Zn的累积情况进行了预测,结果表明:随着时间的推移,土壤有害元素含量会有所增高。其中,大气降尘中Zn元素对青岛市区土壤影响明显。该研究对于正确认识青岛区域地球化学特征和地质环境具有一定的指导意义。 相似文献
65.
Lu Liu Mingzhu Fu Kaiming Sun Qinzeng Xu Zongjun Xu Xuelei Zhang Zongling Wang 《海洋学报(英文版)》2021,40(6):92-99
The waters near the Antarctic Peninsula have always been a study hot spot because of their variable and unique oceanographic conditions.To determine the distribution and possible influencing factors on phytoplankton size and abundance near the Antarctic Peninsula,a large-scale survey was conducted during the austral summer of2018.Samples were collected in 27 stations located in the Drake Passage(DP),South Shetland Islands(SSI),and South Orkney Islands(SOI).Phytoplankton communities were described using chlorophyll a(Chl a),flow cytometry and light microscopy to cover a size range from pico-to microphytoplankton.Nanophytoplankton,especially small nanophytoplankton(2-6 μm) with abundance ranging from 0.66 ×10~3 cells/mL to 8.46 ×10~3 cells/mL,was predominant throughout the study area.Among different regions,there was an obvious size shift.The proportion of picophytoplankton near the Elephant Island(EI) and DP was higher than other regions,and larger cells were found mainly in east of SOI.The distribution of phytoplankton abundance detected by flow cytometry was not completely consistent with Chl a concentrations due to the contribution of larger cells to Chl a.Possible influencing factors on the phytoplankton size distribution were discussed.The properties of water masses such as temperature and salinity can influence the phytoplankton size distribution.Correlation analysis revealed that only picophytoplankton is significantly correlated with salinity.Light and Fe availability might affect phytoplankton abundance and size distribution especially near the waters of SSI and EI in this study.It was also speculated that the abundance of cryptophytes is possibly related to ice melting. 相似文献
66.
Qiao Chen Decheng Hao Zongjun Gao Mengjie Shi Min Wang Jianguo Feng Qinghai Deng Lu Xia Chunrong Zhang Yongbo Yu 《Ground water》2020,58(6):882-891
A typical area, Gaomi City in China, was chosen to discuss the enrichment process of groundwater fluorine in sea water intrusion area. The groundwater had fluorine levels of 0.09–10.99 mg/L, with an average concentration of 1.38 mg/L. The high-fluorine groundwater was mainly distributed in the unconsolidated Quaternary sediments, where concentrations in 83.6% of the samples exceeded the national limit of 1.0 mg/L. The groundwater in the Quaternary sediments also had higher levels of Cl−, TDS, Mg2+, and pH and lower levels of Ca2+, Co, Ni, and Cu than that in the bedrock. The groundwater fluorine levels in the Quaternary sediments are positively correlated with Cl−, TDS, Mg2+, pH, and negatively correlated with Ca2+, γCa2+/γMg2+, Co, Ni, Cu. Geochemical indices of Cl− and TDS indicate sea water intrusion in the Quaternary high-fluorine groundwater area (F− > 1.0 mg/L), while they do not indicate any intrusion in the bedrock area. The chemical weathering of minerals was intensified with the intrusion of sea water. Cation exchange was confirmed to occur in the Quaternary sediments and was promoted by sea water intrusion. Cation exchange consumes part of groundwater Ca2+ and permits more F− dissolving. Consequently, in the Quaternary sediments, the groundwater was supersaturated with CaF2 minerals and undersaturated with MgF2 minerals when F− > 1.0 mg/L, while CaF2 and MgF2 minerals both are undersaturated when F− < 1.0 mg/L. Thus, the chemical weathering of minerals and cation exchange caused by sea water intrusion are the crucial processes controlling the groundwater fluorine levels, which should be considered when the groundwater fluorine enrichment mechanism is discussed along coastal zones. 相似文献
67.
We report multi-wavelength observations of four solar flares on 2014 July 07.We firstly select these flares according to the soft X-ray(SXR)and extreme ultraviolet(EUV)emissions recorded by the Extreme Ultraviolet Variability Experiment and Geostationary Orbiting Environmental S atellites.Then their locations and geometries are identified from the full-disk images measured by the Atmospheric Imaging Assembly(AIA),and the time delays among the light curves in different channels are identified.The electron number densities are estimated using the differential emission measure method.We find that three of four flares show strong emissions in SXR channels and high temperature(>6 MK)EUV wavelengths during the impulsive phase,i.e.,AIA 131 A and 94 A,and then they emit peak radiation subsequently in the middle temperature(~0.6-3 MK)EUV channels.Moreover,they last for a long time and have smaller electron densities,which are probably driven by the interaction of hot diffuse flare loops.Only one flare emits radiation at almost the same time in all the observed wavelengths,lasts for a relatively short time,and has a larger electron density.It is also accompanied by a typeⅢradio burst.The bright emission at the EUV channel could be corresponding to the associated erupting filament. 相似文献
68.
为了解不同农业施肥管理方式对水体浮游植物群落的影响,本研究以江苏句容戴庄有机示范村和常规农业管理区池塘浮游植物为对象,分析冬夏两季浮游植物群落特征及相关水环境因子.结果表明:冬季有机和常规农业区域的浮游植物分别检到7门95种和7门111种,夏季分别检到7门102种和6门112种,有机农业区浮游植物由冬季的隐藻—绿藻型向夏季的蓝藻—绿藻型变化,常规农业区从隐藻—绿藻型向蓝藻—硅藻型变化,蓝藻逐渐取代隐藻的优势地位.夏季各池塘浮游植物alpha多样性没有显著的区域差异,但冬季常规农业区浮游植物物种丰富度、蓝藻和裸藻的Shannon-Wiener多样性指数显著较高.指示物种分析显示,谷皮菱形藻(Nitzschia palea)和梅尼小环藻(Cyclotella meneghiniana)为有机农业区指示物种,而梭形裸藻(Euglena acus)、针形纤维藻(Ankistrodesmus acicularis)、肘状针杆藻(Synedra ulna)和狭形纤维藻(Ankistrodesmus angustus)为常规农业区指示物种,此6种藻为中、富营养化藻类,说明水体氮磷营养盐浓度较高,这与... 相似文献