不同溶剂对沉积物碳酸盐组分中硼的提取和硼同位素组成的影响的研究          下载免费PDF全文

杨剑  马云麒  彭章旷  李海军  柴小丽  肖应凯  张艳灵 《盐湖研究》2018,26(3)

本实验研究了采用不同溶剂（盐酸、醋酸、饱和EDTA-2Na盐等）对沉积物样品中的碳酸盐组分硼元素提取和硼同位素组成的影响。结果表明,1mol/L的醋酸是溶解沉积物样品中碳酸盐组分的最佳溶剂,能将沉积物中的碳酸盐完全溶解,并有效避免样品中石膏、硅酸盐等矿物的溶出,对其中铁的氧化物等影响也比较小,同时,过硼特效树脂前将溶液调至弱碱性所用的亚沸氨水的量较少,从而引入的本底较少。采用盐酸和饱和EDTA-2Na溶液溶解沉积物,容易将沉积物中除碳酸盐以外的矿物中的硼溶出,如石膏、硅酸盐矿物等,不利于碳酸盐组分中硼的提取。  相似文献   

北京城市居民日常活动空间的社区分异   总被引：3，自引：0，他引：3  

张艳  柴彦威  郭文伯 《地域研究与开发》2014,(5)

居民日常活动空间直接反映其对城市空间的利用状况及生活质量,从而得到地理学、规划学、社会学等领域的关注。中国城市在市场化转型、快速城市化等背景下,社会阶层分化与居住空间分异日益明显,城市社区无论在社会构成还是在建成环境上都呈现出显著的空间分异。基于对北京城市居民活动日志问卷调查数据,借助GIS可视化与空间分析方法,通过对北京城市不同类型社区居民日常活动的时空分布、活动空间形态及面积等特征的比较,揭示不同社区居民的日常活动空间的社区分异,试图将基于人口属性、设施供给的社区分异研究拓展到基于日常行为的居民对城市空间利用的社区分异。  相似文献   

Prevalence and risk assessment of antibiotics in riverine estuarine waters of Larut and Sangga Besar River,Perak     

Low  Kyleyoung  Chai  Layching  Lee  Choonweng  Zhang  Gan  Zhang  Ruijie  Vahab  Vaezzadeh  Bong  Chuiwei 《中国海洋湖沼学报》2021,39(1):122-134

Antibiotics released into the environment through anthropogenic activities exert selective pressure,driving bacteria towards increasing antimicrobial resistance.The prevalence of antibiotics and the ecological risks posed in the riverine estuarine of Larut River and Sangga Besar River,which included wastewater effluents from hospital,zoo,and poultry slaughterhouse sources were investigated.Solid phase extraction(SPE) followed by high-performance liquid chromatography tandem mass chromatography(HPLC-MS/MS) were used to extract and quantify the antibiotic residues from 22 antibiotics belonging to six major antibiotic classes(sulfonamide,macrolide,fluoroquinolone,phenicol,trimethoprim,and tetracycline).Sixteen antibiotic residues were detected with concentrations ranging from limit of detection(LOD) to 1 262.3 ng/L.Fluoroquinolones and macrolides were the most frequently detected compounds.Erythromycin,clarithromycin and ofloxacin detected in hospital and zoo effluents posed a high risk to algae while tetracycline had low to medium ecological risks toward all the relevant organisms from aquatic environments(algae,invertebrate Daphnia magna,and fish).  相似文献   

Mesoscale experimental study on chemical composition,pore size distribution,and permeability of tailings     

Zengguang Xu  Yang Yang  Junrui Chai  Xuemin Yang  Yuan Qin  Yanlong Li 《Environmental Earth Sciences》2017,76(20):707

To study the seepage characteristics of tailing sand, an indoor sand column test was performed with three kinds of tailing sand obtained from Henan and Shaanxi provinces, China. River sand, quartz sand, and glass beads were also employed for comparison. Using the nuclear magnetic resonance, the researchers studied pore size distribution and permeability under different hydraulic gradients. The chemical composition and particle morphology were analyzed by energy-dispersive spectrometry and X-ray diffraction. The results were as follows. (1) The three kinds of tailings sand are small in diameter, mainly in the range from 0.15 to 0.5 mm. Their diameter distribution is more concentrated than river sand. The surface of tailing sand is rough. As for chemical composition, tailing sand contains many kinds of metal elements. (2) With hydraulic gradient increasing, the micropores in the tailings samples become fewer, the larger pores grow in number, and the peak of the pore size distribution changes to the left; blocking is more obvious. (3) The small pores gradually decrease during the test. Under the influence of groundwater pressure, the smaller gravel could migrate and block tiny pores. The structure of particle arrangement becomes denser. Therefore, it would prevent the seepage liquid from passing through the medium. The permeability coefficient K decreases.  相似文献   

Understanding the characteristic of GLONASS inter-frequency clock bias using both FDMA and CDMA signals     

Zhang  Fan  Chai  Hongzhou  Li  Linyang  Wang  Min  Feng  Xu  Du  Zhenqiang 《GPS Solutions》2022,26(2):1-19

GPS Solutions - High-frequency global navigation satellite system (GNSS) observations are of great significance for structural health monitoring. At present, most studies on high-frequency GNSS...  相似文献