首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 125 毫秒
1.
运用三维荧光光谱(EEMs)技术结合平行因子分析法(PARAFAC)以及紫外-可见光谱技术(UV-vis),对周村水库季节演替过程中沉积物上覆水溶解性有机物(DOM)的紫外-可见以及三维荧光光谱特征进行分析.结果表明:周村水库上覆水的总氮、溶解性总氮、总有机碳和溶解性有机碳的季节性差异显著,并且冬季总氮浓度最高、夏秋季总有机碳浓度较高;夏秋季上覆水DOM的吸收系数a254a355均高于冬春季,与有机物的分布相一致;4个季节上覆水DOM的E3/E4均大于3.5,说明DOM以富里酸为主,E2/E3(富里酸占DOM的比例)在夏秋季低于冬春季,而且各季节SR均大于1,表明DOM主要为生物源;三维荧光通过PARAFAC解析出3种组分:类腐殖质(C1)、可见区富里酸(C2)和类蛋白(C3);对3个组分进行相关性分析,结果显示C1、C2、C3之间具有显著的相关性;DOM的总荧光强度以及各组分的荧光强度均呈现出夏秋季高、冬春季低的特征,且各季节间差异显著;周村水库4个季节的DOM生物源指数(BIX)在0.8~1.0之间,表明水库DOM具有较强的自生源特征,与腐殖程度指标(HIX)的结果相吻合;主成分分析显示周村水库上覆水DOM的光谱特征差异明显,夏秋季的DOM光谱特征相近、冬春季的水体DOM特征相似;并且组分C1、C2、C3与DOM特征参数(a254、SUVA280HIXFIBIX)以及溶解性有机碳呈显著相关.各荧光组分与水质参数(溶解性总氮和溶解性有机碳)的多元线性回归呈现很好的拟合,通过建立回归方程可以为以后研究周村水库水体四季的DOM光谱特征,分析水库水体的有机物污染特征,并为水库水质管理提供技术支持.  相似文献   

2.
峡谷分层型水源水库表层沉积物溶解性有机物光谱特征   总被引:7,自引:1,他引:6  
结合三维荧光光谱技术(EEMs)与紫外吸收光谱(UV-vis),并利用平行因子分析(PARAFAC)的方法,对金盆水库表层沉积物中溶解性有机质(DOM)光谱的空间分布特征及来源进行分析,并探讨沉积物DOM的荧光组分与可溶性有机氮(SON)、可溶性无机氮(SIN)之间的相关性.结果表明,金盆水库表层沉积物DOM由3类荧光组分组成,分别是类富里酸C1(235 nm,315 nm/430 nm)、类色氨酸C2(220 nm,275 nm/330 nm)和类胡敏酸C3(265 nm/520 nm),各组分荧光强度占总荧光强度百分比的平均值分别为43.15%、31.54%和25.31%.表层沉积物DOM浓度在空间上呈现从上游到主库区先减少后增加的趋势.光谱斜率S275-295S350-400和光谱斜率比SR反映出各采样点陆源与内源占比的差异性.荧光指数、自生源指标和腐殖化指标都表明金盆水库沉积物DOM的来源具有内源与陆源双重特征.相关性分析表明,表层沉积物DOM各组分与SON和SIN均呈显著正相关,说明DOM与氮元素的迁移转化密切相关.  相似文献   

3.
作为海陆交互作用的重要区域,河口在海洋碳循环中扮演着重要角色.近年来,溶解性有机质(dissolved organic matter,DOM)在河口区的来源、降解和保存一直是关注的热点.本研究结合三维荧光光谱和紫外可见吸收光谱,对珠江口3个沉积柱(S1、S2、S3站位,盐度依次增加)孔隙水溶解性有机质的空间分布和来源进行了表征分析.利用平行因子分析(parallel factor analysis,PARAFAC)方法对三维荧光光谱数据进行解析共得到5种荧光组分:类腐殖质组分C1、C3、C4,以及类蛋白荧光组分C2和C5.三个站位的C2组分同沉积物微生物DNA浓度表现出显著的正相关关系(R2=0.69,P<0.01),说明类蛋白组分C2可能主要来源于原位微生物的分解代谢.C5同DNA浓度相关性较弱(R2=0.40,P<0.05),推测是混入了荧光峰同类蛋白组分十分接近的酚类化合物所致.类腐殖质荧光组分来源复杂,S1站位类腐殖质荧光组分含量最高(1.45~8.83R.U.),推测是受到了显著的陆源输入影响.S2和S3站位3种类腐殖质荧光组分含量很低(<1R.U.),且分布规律十分相似,可能主要来源于水体和沉积物藻类微生物的代谢释放.三个站位的腐质化指标HIX随深度增加,类蛋白组分荧光相对含量随深度降低,并且同指示DOM分子量的光谱斜率比值SR分别呈显著的负相关和正相关关系.这说明从沉积物表层到深层,DOM由低分子量的类蛋白组分向高分子量的类腐殖质组分过渡.本研究结果对理解河口区沉积物中的孔隙水DOM分子量/活性模型(pore water size/reactivity,PWSR)以及DOM的生物有机地球化学过程提供了补充参考.  相似文献   

4.
为探究引黄水源水库——门楼水库平水期和丰水期有色可溶性有机物(CDOM)的组成特征、来源及差异,运用紫外—可见光谱技术(UV-vis)和三维荧光光谱(EEMs)技术,结合平行因子分析法(PARAFAC)分析2022年5月(平水期)和2022年7月(丰水期)有色可溶性有机物含量及组分变化。研究结果表明:PARAFAC识别出2类荧光组分,分别是C1(Ex=355 nm,Em=476 nm,类腐殖质组分)和组分C2(Ex=225 nm,Em=320 nm,类蛋白组分);丰水期CDOM组分荧光强度显著高于平水期。CDOM光谱参数表明,门楼水库水体处于中营养状态,水体CDOM受新生内源和外源输入共同影响,以自生源为主;水库CDOM具有相对分子量小、腐殖化程度较弱的特点。丰水期水库富营养化水平和CDOM相对浓度低于平水期;丰水期CDOM疏水性组分比例和芳香化程度高于平水期。水质理化指标、CDOM组分和光谱参数相关性分析结果表明SUVA260和SUVA280与DOC呈显著负相关,说明紫外—可见光谱参数在一定程度上可以用来估算DOC的浓度;Chl.a浓度作为...  相似文献   

5.
李雅妮  徐华成  江和龙 《湖泊科学》2020,32(4):1029-1040
溶解有机质(DOM)在环境水体中广泛存在,具有连续的分子量分布特征,并可显著影响水体中污染物的迁移转化和归趋行为.于2019年春季采集鄱阳湖全湖水样,采用超过滤技术将DOM样品分为低分子量(LMW,1 kDa)和高分子量(HMW,1 kDa~0.45μm)组分,通过三维荧光光谱结合平行因子分析(EEM-PARAFAC)和ICP-MS分析不同分子量区间有机组分和重金属含量.结果表明,鄱阳湖水体DOM中LMW-DOM占比为43%~55%,HMW-DOM占比为45%~57%.平行因子模型提取出3个相互独立的荧光组分,分别为类富里酸组分C1、C2和类腐殖酸组分C3. 60%~73%的C1分布在LMW中,77%~93%的C2分布在HMW中,而C3几乎平均分布在LMW-和HMW-DOM中,可能与C1、C2、C3组分分别含有的传统荧光峰有关.通过对荧光参数FIX(1.4)、BIX(0.8)的计算发现鄱阳湖DOM陆源特征显著,且HMW组分具有比LMW组分更高的陆源特征和芳香度.重金属检测结果表明Cr、Mn、Fe、Pb则主要分布在HMW中(63%~94%),As、Cd、Ba、Se、Sb主要分布在LMW中(63%~84%),Cu、Zn、Ni、Co几乎均匀分布在LMW-和HMW-DOM中.重金属与DOM的相关性结果表明大多数金属与C2占比呈负相关,与C3占比呈正相关,说明重金属离子与水体中DOM的络合可能主要通过腐殖类组分C3进行.且重金属含量的分布受HMW-DOM的影响较大,说明人类活动也对鄱阳湖水体的重金属分布有着重要影响.  相似文献   

6.
随着人类活动和气候变化影响的加剧,降雨特征变化引发的洪水问题日益突出,探讨其时空演变特征对保障高度城镇化地区洪涝安全有较大理论和实际意义.本研究以高度城镇化的太湖平原地区为例,选取降雨强度、降雨历时、降雨集中程度和降雨峰值程度为降雨类型特征指标,以高分辨率短历时加权集合降水资料MSWEP (multi-source weighted-ensemble precipitation)为基础探讨了快速城市化发展下(1979—2016年)不同降雨历时-强度-类型的时空演变规律及其演变机制.研究结果表明:①研究区的降雨频次呈现出强度小、历时短、雨量集中于中期和高峰型降雨发生的频次高的特征;同时历时较短、集中于前期和后期的降雨频次趋于增加,而历时较长、集中于中期且中峰型降雨的频次趋于减少.②城镇化对降雨雨型的影响分析发现,高城镇化水平地区较低城镇化水平地区的降雨量更大,其中降雨强度大于25 mm/d的大雨和暴雨事件更易发生;并且更倾向于发生前期型和高峰型的极端分布降雨.随着城镇化发展研究区更易于遭受因降雨量过于集中而导致的雨涝灾害.  相似文献   

7.
采用三维荧光光谱-平行因子法(EEMs-PARAFAC)分析太湖五里湖水体悬浮物中水溶性有机质(WSOM)的荧光光谱特征,研究其组分类型、分布规律以及来源,进一步探讨悬浮物中水溶性有机氮和无机氮含量与WSOM荧光组分之间的关系.结果表明,悬浮物中WSOM荧光组分主要由2个类腐殖质(C1、C2)和1个类色氨酸类蛋白质(C3)组成.总荧光强度在57.56~200.01 R.U./g之间,平均为115.42 R.U./g,其中C1、C2、C3的相对比例分别为35.55%、34.05%和30.40%;空间上由西向东逐渐增强,东五里湖高于西五里湖,沿岸区高于湖心区.荧光指数和生物源指数变化范围分别在1.48~2.34和0.65~0.87之间,反映了悬浮物中WSOM主要来源于微生物、藻类的自生生物源.多元回归统计分析结果表明,悬浮物WSOM与氮元素的迁移转化密切相关,且有机氮与WSOM荧光组分的相关系数大于无机氮.  相似文献   

8.
利用碳稳定同位素、紫外-可见吸收和三维荧光光谱和傅里叶变换离子回旋共振质谱等手段,分区域研究了2019年5月浙江象山港这一代表性的半封闭富营养化港湾水体可溶性有机质(DOM)的组成、来源,并初步推断了其迁移转化过程.通过三维荧光建模识别出一个类蛋白荧光组分(C1)和两个类腐殖质荧光组分(C2和C3),利用高分辨率质谱获得了各类分子的数量和相对强度.可溶性有机碳(DOC)浓度, C2、C3和黑碳类分子组分的相对强度均和盐度呈显著负相关,指示象山港存在海水对陆源信号的稀释作用.象山港在空间上光透射能力存在差异从而导致光降解程度不同,光降解作用可能在象山港惰性有机质转化中发挥了重要作用. C1组分和盐度的弱相关性表明自生源不能主导象山港地区的类蛋白荧光组分,富营养化条件下外源(如人类输入、孔隙水释放)均影响了类蛋白荧光组分的分布.将象山港和我国其他代表性沿海港湾对比,可发现象山港的类蛋白荧光组分在荧光溶解有机质(FDOM)中的相对占比处于中等水平.在富营养化背景下,人类活动输入可能是我国港湾DOM的重要来源.  相似文献   

9.
基于2017年1-12月在抚仙湖开展的逐月观测,利用紫外-可见吸收光谱和三维荧光光谱技术探讨该湖有色可溶性有机物(CDOM)的来源组成及时空变化特征.12个月CDOM吸收值a(254)的均值为3.47±0.57 m-1,范围为1.82~5.22 m-1,说明CDOM丰度较低.平行因子分析结果给出了2种类酪氨酸荧光组分(C1和C3)、1种类色氨酸荧光组分(C2)、1种类腐殖质荧光组分(C4),12个月内源组分(C1+C3)对总荧光强度的平均贡献为65.81%±15.38%,外源组分(C2+C4)的平均贡献为34.19%±15.38%;荧光指数FI的均值为1.73±0.14,腐殖化指数HIX的均值为1.02±0.37,生源化指数BIX的均值为1.23±0.27,说明CDOM主要为微生物内源产生.时空变化方面,春(3-5月)、夏(6-8月)、秋(9-11月)和冬(1、2、12月)季的a(254)分别为3.20±0.47、3.76±0.64、3.67±0.50和3.23±0.38 m-1,夏季和秋季均显著高于冬季和春季;CDOM丰度及内外源组分的空间分布具有季节异质性,可能与流域土地利用、河流输入、降雨、温度、光辐射等因素有关.  相似文献   

10.
高邮湖、南四湖和东平湖作为南水北调东线枢纽湖泊,其水质状况对保障调水安全起到关键性作用本文运用三维荧光光谱平行因子分析法(EEMs-PARAFAC)分析了3个湖泊在不同水文情景下有色可溶性有机物(CDOM)吸收、荧光光谱特征以及荧光组分与主要水质参数的相关性,以探究3个湖泊CDOM来源组成特征结果表明,平行因子分析法解析CDOM三维荧光图谱,得到陆源类腐殖质C1、类色氨酸C2和类酪氨酸C3不同水文情景对高邮湖CDOM来源与结构组成影响较明显,丰水期其类腐殖质荧光强度显著大于枯水期(t-test,P0.01),并且与a(254)呈正相关(R~2=0.85,P0.01),表明类腐殖质是CDOM主要部分,该荧光组分贡献率可达50%[F_(max)C1/(F_(max)C1+F_(max)C2+F_(max)C3)×100%],高邮湖受到入湖河流来水的影响较大,丰水期入湖口附近荧光强度明显高于其他水域东平湖和南四湖CDOM来源组成特征相似,丰水期东平湖和南四湖组分C2和C3显著低于枯水期(t-test,P0.01),两湖泊枯水期工农业等人为污染源影响较大相关性分析表明高邮湖中类腐殖质荧光特征在一定程度是能反演DOC浓度,并且类腐殖质的输入会增加湖泊总磷、总氮和叶绿素a浓度而东平湖和南四湖CDOM荧光特征与主要水质参数的相关性较差,这与高邮湖水体存在较大差异.  相似文献   

11.
Exploring the chemical characterization of dissolved organic matter (DOM) is important for understanding the fate of laterally transported organic matter in watersheds. We hypothesized that differences in water-extractable organic matter (WEOM) in soils of varying land uses and rainfall events may significantly affect the quality and the quantity of stream DOM. To test our hypotheses, characteristics of rainfall-runoff DOM and WEOM of source materials (topsoil from different land uses and gullies, as well as typical vegetation) were investigated at two adjacent catchments in the Loess Plateau of China, using ultraviolet–visible absorbance and excitation emission matrix fluorescence with parallel factor analysis (PARAFAC). Results indicated that land-use types may significantly affect the chemical composition of soil WEOM, including its aromaticity, molecular weight, and degree of humification. The PARAFAC analysis demonstrated that the soils and stream water were dominated by terrestrial/allochthonous humic-like substances and microbial transformable humic-like fluorophores. Shifts in the fluorescence properties of stream DOM suggested a pronounced change in the relative proportion of allochthonous versus autochthonous material under different rainfall patterns and land uses. For example, high proportions of forestland could provide more allochthonous DOM input. This study highlights the relevance of soils and hydrological dynamics on the composition and fluxes of DOM issuing from watersheds. The composition of DOM in soils was influenced by land-use type. Precipitation patterns influenced the proportion of terrestrial versus microbial origins of DOM in surface runoff. Contributions of allochthonous, terrestrially derived DOM inputs were highest from forested landscapes.  相似文献   

12.
The influence of dissolved organic matter (DOM) on mineral extraction from salt lake brines depend on DOM quality. This study contributes to our knowledge of DOM’s metal binding behavior in hypersaline environments by characterization of DOM from lakes in the Qaidam Basin, i.e., Qarhan Lake (LQDOM), Da Qaidam (DQDOM) and West Ginair Salt Lake (WGDOM). The DOM was fractionated based on solid phase extraction (SPE) and ultrafiltration (UF), and the spectral and metal binding behavior of these fractions were studied by absorption spectroscopy, Pb(II) titration techniques and fluorescence parallel factor (PARAFAC) analysis. The results showed that bulk DOM generally contained more dissolved organic carbon (DOC), lower specific UV absorbance (SUVA254), higher fluorescence and biological indices, comparable humification index, and lower condition stability constants compared to the other nature waters. Compared with UF, SPE-derived DOM exhibited higher DOC recovery and aromaticity and lower carbohydrate yield. It appeared that the SPE procedure used affects the spectral composition of bulk DOM to a larger extent than UF. Source and molecular weight (MW)-dependent differences in abundance and quality of brine DOM was indicated by higher SUVA254 in high MW DOM, for LQDOM and DQDOM, and humic-like fluorophores were mainly in high MW-DOM in each lake. Moreover, the high MW humic-like component exhibited higher metal binding potential than the bulk and low MW counterparts for LQDOM and DQDOM, while the inverse was observed for WGDOM. This study revealed the effects of isolation techniques on interpretation of DOM characteristics, and meanwhile highlighted the importance of origin- and MW-dependent DOM in manipulating the behavior, fate, and bioavailability of heavy metals in salt lake brine.  相似文献   

13.
The fluorescence and molecular weight characteristics of dissolved organic matter (DOM) in groundwater of Bangladesh were investigated to evaluate its multiple roles on arsenic (As) mobilization and poisoning. Fluorescence properties of DOM were measured in groundwater samples collected from two As contaminated areas of Bangladesh (Faridpur at the Ganges floodplain and Sonargaon at the Meghna floodplain) from different locations and depths. The three dimensional excitation–emission matrix (3DEEM) fluorescence spectra of groundwater samples showed two characteristic peaks around Ex/Em = 335–365 nm/435–480 nm for fulvic-like peaks and peak at around Ex/Em = 275–290 nm/310–335 nm for the protein-like materials. The similarity of fluorescence spectra of groundwater and surface water of both the study areas with high intensity of fluorescence and its strong correlation with DOC reflect the in situ generation of fluorescent DOM from sedimentary organic matter (SOM) and recent recharge of terrestrial labile organic carbon into shallow aquifer. High performance size-exclusion chromatography (HPSEC) analysis of DOM shows positive correlations between fluorescence intensities (FI) of small molecular fractions (0.65 kDa) and As concentrations, with the signatures of protein-like peaks of DOM in groundwater. This result provides new evidence that small molecular weight fraction of DOM in groundwater of Bangladesh can play an important role on As mobilization and toxicity. In addition, high concentration of fluorescence materials in DOM of As contaminated groundwater of Bangladesh may pose a threat to public health.  相似文献   

14.
The rainstorm of 17 to 21 July 1981 which caused exceptionally heavy rains and floods in arid Rajasthan, was analysed. It was observed that 7 stations in the rainstorm area broke their previous 80-year record of one-day rainfall, and two of these stations equalled their respective estimates of probable maximum precipitation (PMP). A comparison of areal raindepths of this rainstorm with the similar raindepths of past severe-most rainstorms of this region showed that this rainstorm gave unprecedented raindepths up to about 38 850 sq. km (i.e. 15 000 sq. miles) for a 3-day duration.  相似文献   

15.
We applied stable carbon isotopes, ultraviolet-visible absorption(UV-Vis), fluorescence excitation-emission matrices spectroscopy(EEMs), and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS) to investigate the chemical composition and sources of the dissolved organic matter(DOM) in both the water column and pore water in Xiangshan Bay, a representative semi-enclosed and eutrophic bay in Zhejiang Province, China. One protein-like fluorescent component(C1) and two humic-like fluorescent components(C2 and C3) were identified by PARAFAC modeling. The concentration of dissolved organic carbon(DOC), the relative intensities of C2, C3, and black carbon-like compounds are all negatively correlated with salinity, indicating that there is a dilution effect of terrestrial signals by seawater in Xiangshan Bay. The differences in light penetration ability of Xiangshan Bay cause different degrees of photo-degradation, which may play an important role in the transformation of organic matter in Xiangshan Bay. The weak correlation between the C1 fluorescent component and salinity indicates that autochthonous sources cannot dominate the protein-like FDOM in the Xiangshan Bay drainage area. Multiple sources(such as anthropogenic inputs and release of pore water) also affect the distribution of the protein-like fluorescent component under eutrophication conditions. The relative proportion of the protein-like fluorescent component in Xiangshan Bay is on a medium level in China and anthropogenic inputs may be a significant source of DOM in coastal bays.  相似文献   

16.
Using fluorescence spectroscopy and parallel factor analysis (PARAFAC) we characterized and modeled the fluorescence properties of dissolved organic matter (DOM) in samples from the Penobscot River, Androscoggin River, Penobscot Bay, and the Gulf of Maine (GoM). We analyzed excitation-emission matrices (EEMs) using an existing PARAFAC model (Cory and McKnight, 2005) and created a system-specific model with seven components (GoM PARAFAC). The GoM PARAFAC model contained six components similar to those in other PARAFAC models and one unique component with a spectrum similar to a residual found using the Cory and McKnight (2005) model. The unique component was abundant in samples from the Androscoggin River immediately downstream of a pulp mill effluent release site. The detection of a PARAFAC component associated with an anthropogenic source of DOM, such as pulp mill effluent, demonstrates the importance for rigorously analyzing PARAFAC residuals and developing system-specific models.  相似文献   

17.
Continuous monitoring of dissolved organic matter (DOM) character and concentration at hourly resolution is rare, despite the importance of analysing organic matter variability at high‐temporal resolution to evaluate river carbon budgeting, river water health by detecting episodic pollution and to determine short‐term variations in chemical and ecological function. The authors report a 2‐week experiment performed on DOM sampled from Bournbrook, Birmingham, UK, an urban river for which spectrophotometric (fluorescence, absorbance), physiochemical (dissolved organic carbon [DOC], electrical conductivity, pH) and isotopic (D/H) parameters have been measured at hourly frequency. Our results show that the river had sub‐daily variations in both organic matter concentration and characteristics. In particular, after relatively high‐magnitude precipitation events, organic carbon concentration increased, with an associated increase in intensity of both humic‐like and tryptophan‐like fluorescence. D/H isotopic ratio demonstrates different hydrological responses to different rainfall events, and organic matter character reflects this difference. Events with precipitation < 2 mm typically yielded isotopically heavy water with relatively hydrophilic DOM and relatively low specific absorbance. Events with precipitation > 2 mm had isotopically lighter water with higher specific absorbance and a decrease in the proportion of microbially derived to humic‐like fluorescence. In our heavily urbanized catchment, we interpret these signals as one where riverine DOM is dominated by storm sewer‐derived ‘old’ organic matter at low‐rainfall amounts and a mixed signal at high‐precipitation amounts where ‘event’ surface runoff‐derived organic matter dominate during storm sewer and combined sewer overflow routed DOM. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

18.
郑达燕  刘睿  张柳柳  郑财贵  张静 《湖泊科学》2023,35(4):1343-1358
三峡库区拥有目前世界上规模最大的水利枢纽工程,自投入使用以来,为长江流域提供了丰富的水源及电力,促进了经济的发展,但同时也对该区域的生态环境造成了严重的冲击。澎溪河流域作为三峡库区长江流域干流的典型回水区和消落带,是众多学者研究三峡库区生态环境变化的重点区域。为探究不同时空尺度下土地利用对河流溶解性有机质(DOM)的影响,以澎溪河流域为研究对象,基于紫外-可见光谱分析和三维荧光光谱矩阵-平行因子分析,结合河段缓冲区、河岸带缓冲区及子流域3种空间尺度的二级土地利用类型,解析了旱雨季水体DOM的组成及来源特征,并采用相关分析和冗余分析方法探讨了3种空间尺度下土地利用方式对旱雨季水体DOM的多时空尺度影响。结果表明:(1)旱季水体DOM荧光组分以陆源类腐殖质所占比例更大,雨季水体DOM荧光组分以富里酸贡献为主。(2)流域内陆源输入和内源产生对水体DOM丰度均有贡献,雨季较旱季水体DOM的陆源性更强,自生源特征较弱。(3)土地利用在雨季和子流域尺度下对水体DOM的影响更显著,其中,雨季子流域尺度下,土地利用指数对水体DOM参数的解释率为90.35%。(4)不同土地利用方式对水体DOM产生的影响...  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号