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81.
A multi‐element ion‐pair extraction method was described for the preconcentration of Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), and Zn(II) ions in environmental samples prior to their determinations by flame atomic absorption spectrometry (FAAS). As an ion‐pair ligand 2‐(4‐methoxybenzoyl)‐N′‐benzylidene‐3‐(4‐methoxyphenyl)‐3‐oxo‐N‐phenyl‐propono hydrazide (MBMP) was used. Some analytical parameters such as pH of sample solution, amount of MBMP, shaking time, sample volume, and type of counter ion were investigated to establish optimum experimental conditions. No interferences due to major components and some metal ions of the samples were observed. The detection limits of the proposed method were found in the range of 0.33–0.9 µg L?1 for the analyte ions. Recoveries were found to be higher than 95% and the relative standard deviation (RSD) was less than 4%. The accuracy of the procedure was estimated by analyzing the two certified reference materials, LGC6019 river water and RTC‐CRM044 soil. The developed method was applied to several matrices such as water, hair, and food samples. 相似文献
82.
83.
沉积物中磷的赋存形态及磷形态顺序提取分析方法 总被引：11，自引：1，他引：10
阐述了当前我国水体富营养化的现状,水体的富营养化与水体中磷、氮的浓度以及二者的浓度比值有着密切的关系。水体富营养化时氮和磷的浓度均很高,但没有一个固定的值,是在一个较宽泛的富营养范围内,氮和磷的浓度比值大多在10∶1～20∶1。湖泊沉积物作为湖泊水体中磷的重要蓄积库,是湖泊流域磷循环的重要归属,也是湖泊水体内源性磷的主要来源,沉积物中极少量的稳定磷转化为活性磷就会造成湖泊水体富营养化。文中介绍了沉积物中无机磷形态的分类,评述了欧盟标准局在研制湖泊沉积物磷形态标准物质时比对采用的4种提取方法(Willimas法、Hieltjes-Lijklema法、Ruttenberg法、Golterman法),总结了国内外学者所应用的沉积物中磷的各种形态提取方法和磷各形态的分析测定方法,国内学者应用的方法是在国外学者方法的基础上提出的,阐述了顺序提取方法及其地球化学意义。简要评述了湖泊沉积物中磷的生物释放、物理释放和化学释放三种释放机制,这三种释放机制相辅相成,在一特定的环境条件下某一过程可能占主导地位来控制沉积物磷的释放。最后提出应该加强对沉积物中磷的各种形态的专属提取剂及其提取有效性的分子表征和检测,更加细化对于沉积物中磷形态的分类和创新各种磷形态的分析方法,建立沉积物-水体磷的迁移、循环和转化模型,这对于从根本上解决富营养化问题具有重要意义。 相似文献
84.
研究了野外现场快速准确测定铀矿石中铀的三辛基氧膦(TOPO)萃取α计数法。目前野外现场铀的测量主要采用γ谱法,即利用铀子体的γ射线强度来计算铀的含量,当样品中铀镭处于不平衡状态时,γ谱法测铀存在着较大的测量误差。本文将铀的核性质与化学性质结合起来,采用密闭酸溶法快速溶解样品中的铀,酸溶后的样品不经分离直接在溶样罐中用TOPO萃取,进而测定样品中铀产生的α射线强度获得铀的含量,避免了γ谱法的不足。方法检出限为铀含量2.41μg/g;当铀含量为大约为100μg/g时,测量相对偏差为5.93%;铀的测定范围为7.23μg/g～n%。密闭酸溶法试剂用量少,溶样速度快,且对环境和操作人员污染小;酸溶后的样品用TOPO萃取2 min后即可达到萃取平衡,铀萃取效率在97%以上;所需的仪器设备可以车载形式用于野外现场铀矿石中铀的准确测定,野外应用操作简单、快速、精密度和准确性较高。 相似文献
85.
The accumulation of selenium in evaporation basins (or ponds) in the San Joaquin Valley, California is of a great concern due to its potential hazards to environments. In this study, the accumulation, speciation and concentrations of Se were examined in waters as well as sediments in a system of the evaporation ponds. A significant decrease in the total dissolved Se concentration in Cell 1 in which drainage water with higher Se concentration was pumped from Inlet Channels indicated that the immobilization of Se was active in the Cell 1 and resulted in the higher Se concentration in sediments compared to the terminal cell such as Cell 9. The percentage of reduced Se species such as selenite [Se(IV)] and org-Se of total Se in drainage waters was also found increased in Cell 1 compared to Inlet Channels. The total dissolved Se concentrations in water along flow paths from Cell 1 were relatively constant except for terminal cells such as Cells 9 and 10, which showed higher total dissolved Se concentrations due to evapoconcentration. The percentage of reduced Se forms of total Se was inversely proportional to the percentage of Se(VI) depending on the redox condition of evaporation ponds along the flow paths. Sequential extractions of Se species in sediments indicated that organic associated Se and elemental Se were prevalent forms in sediments in the ponds system. The higher concentrations of elemental Se and organic associated Se in sediments in Cell 1 indicated that the immobilization of Se was active in the sediments compared to Cell 9, while the percentage of both fractions of total Se in sediments in Cells 1 and 9 was relatively constant. The organic materials from algae might provide carbon sources for Se reduction and Se sink in sediments in its elemental and organic associated forms. 相似文献
86.
Two independent analytical methods (sequential extraction and kinetic extraction methods) were applied in order to understand the distribution and speciation of La in the coastal and estuarine sediments from the central east coast of India. Sequential extraction study revealed that La was primarily present as inert complexes (~ 50–60% of the total La) in all the sediments. Amounts of ~ 20–30% of the total La in all the sediments were found to associate with the total organic carbon (TOC) in the sediments. The dissociation rate constants of La–sediment complexes obtained from kinetic extraction studies revealed that the concentration of thermodynamically weak complexes of La gradually increased with the increasing La/TOC ratio in the sediments. 相似文献
87.
通过重金属含量分析,分级提取化学形态分析,结合矿物成分和化学成分分析,对黄龙铺矿区1号尾矿库重金属元素在风化过程中的地球化学行为进行了研究。研究结果表明在横向上,尾矿库中心排水口处地势低洼,铜、铁因相对活泼易于迁移而流失,铅、锌、铬、镉在尾矿库四周的地表浅部淋失,在尾矿库中心则相对富集。化学形态分析表明尾砂中各重金属元素赋存状态各有不同,一般以T6原生硫化物态和T7残渣态为主,铜、锌、铁迁移性较强;其他则较弱,表明对环境威胁不是很大。重金属的迁移明显的分为氧化带和次氧化带,研究结果显示尾矿覆盖方法也不一定能够有效地阻滞污染元素的迁移。 相似文献
88.
对某垃圾填埋场包气带砂土吸附氨氮的机理进行了研究,通过吸附等温实验主要探讨了其吸附过程、不同粒级土的吸附贡献和吸附氨氮的3种形态。结果表明:样品土对氨氮的等温吸附线符合Langmuir模式,原土的计算最大吸附量为435 mg/kg;中砂、细砂和实验原土的吸附能力大小顺序为:原土>细砂>中砂;在样品土中,粉质粘土随着初始铵溶液浓度的升高吸附绝对量和吸附贡献率都在上升,由50 mg/L时的43%贡献率上升到400 mg/L时70%的贡献率,成为原土吸附氨氮的主要贡献者;随着初始铵溶液浓度的升高,水溶态铵、可交换态铵和固定态铵的绝对量都大致呈上升趋势,它们的最大吸附量分别为112.3、97.5和214.0 mg/kg;铵溶液中的铵离子进入粘土中的大致顺序为:颗粒表面的扩散层(主要为水溶态铵)→吸附层(主要为可交换态铵)→矿物晶格内部和晶层空间(主要为固定态铵)。 相似文献
89.
90.