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1.
我国锂钾主要矿产资源大多分布在西部偏远地区,其勘查找矿或综合利用迫切需要现场快速分析技术的支持。本文介绍了自行开发的便携式Li-K分析仪的主要性能及其在锂辉石中锂的分析应用。Li-K分析仪是一种基于大气压的液体阴极辉光放电光谱仪,以待测液体为放电阴极,实现样品中Li、K等元素的原子化和激发。该仪器以光纤传导CCD光谱仪作为检测器,其波长范围为345~1015 nm,分辨率3 nm;以Li 670.78 nm和K 769.90 nm分析谱线,在最佳仪器工作条件下测定Li、K的精密度(RSD,n=14)均低于2%,检出限为0.03 μg/mL,检测范围0.1~10 μg/mL。研究表明,不同酸度和酸的类型对谱线强度影响较大,且存在显著的样品基体效应,标准曲线法分析锂辉石中Li的结果偏差高达267%;而标准加入法可克服基体效应的影响,获得与ICP-OES一致性较好的分析结果,为现场开展固体样品中Li的测定奠定了基础。 相似文献
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X. Drobert C. Fauchard Cte E. Le Brusq E. Guillanton J. Y. Dauvignac Pichot 《Journal of Applied Geophysics》2001,47(3-4)
In the field of road construction and maintenance, the need for information on the thickness of very thin road layers is not satisfied by means of commercial pulse GPR, due to the inability of such devices to operate over ranges of several gigahertz. As a result, research has focused on the design of a step-frequency radar technique, able to work with very high-frequency synthetic pulses.An ultrawide band antenna, belonging to the family of Vivaldi antennas, has been developed for road applications. It has been created using stripline technology and yields a band width greater than one decade. During an initial step, this antenna was tested on various bituminous concrete samples with a network analyzer. Different parameters were studied, including band width, offset between antennas, and height and shape of the frequency-dependent pulse.A second step involved GPR dynamic measurements. A customized software program enabled recording data from the network analyzer. Several radar profiles were developed from selected road construction and maintenance test sites (e.g. the Circular Pavement Fatigue Test Track, composed of a number of known structures). Results show improved resolution when compared to a commercial impulse GPR system. 相似文献
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多目标地球化学调查土壤样品中氮和碳的快速测定 总被引:2,自引:1,他引:2
详细研究了元素分析仪的工作条件,建立了直接固体进样同时测定多目标地球化学调查土壤样苎支氮、碳的方法。方法简便、快速,检出限为氮14.5μg/g、碳0.013%。经土壤国家一级标准物质分析验证,测定值与标准值相符,精密度(RSD,n=12)为氮1.49%-3.27%、碳0.64%~3.63%。 相似文献
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Heping LIU 《大气科学进展》2009,26(1):9-16
Corrections of density effects resulting from air-parcel expansion/compression are
important in interpreting eddy covariance fluxes of water vapor and CO2 when open-path systems
are used. To account for these effects, mean vertical velocity and perturbation of the density
of dry air are two critical parameters in treating those physical processes responsible for
density variations. Based on various underlying assumptions, different studies have obtained
different formulas for the mean vertical velocity and perturbation of the density of dry air,
leading to a number of approaches to correct density effects. In this study, we re-examine
physical processes related to different assumptions that are made to formulate the density
effects. Specifically, we re-examine the assumptions of a zero dry air flux and a zero moist
air flux in the surface layer, used for treating density variations, and their implications
for correcting density effects. It is found that physical processes in relation to the assumption
of a zero dry air flux account for the influence of dry air expansion/compression on density
variations. Meanwhile, physical processes in relation to the assumption of a zero moist air
flux account for the influence of moist air expansion/compression on density variations. In
this study, we also re-examine mixing ratio issues. Our results indicate that the assumption
of a zero dry air flux favors the use of the mixing ratio relative to dry air, while the
assumption of a zero moist air flux favors the use of the mixing ratio relative to the total
moist air. Additionally, we compare different formula for the mean vertical velocity, generated
by air-parcel expansion/compression, and for density effect corrections using eddy covariance
data measured over three boreal ecosystems. 相似文献
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Wei JIANG Xinqing LEE 《中国地球化学学报》2006,25(B08):12-12
Nitrogen cycle is an important bio-geochemical process in the environment. Measurement of the total nitrogen (TN) is a routine experiment in agriculture, biology and environmental sciences. The Kjeldahl method (KM) and elemental analyzer method (EA) are both commonly used to determine TN. Total nitrogen by EA is the sum of nitrate (NO3), nitrite (NO2), organic nitrogen and ammonia. Total nitrogen by KM (TKN) is made up of both organic nitrogen and ammonia. A comparative study focused on the two methods is conducted by analysis of TN in 97 samples from the sediment sequence of Gouchi, a salt lake in North China. KM presents a higher degree of accuracy than EA with a standard deviation of 0.007 vs. 0.024. With the presence of nitrate and/or nitrite nitrogen, however, measurement by KM is considerably lower than that by EA. Therefore, for samples from lake sediment sequences or soils in North China, KM is inapplicable to determining TN because of usually high contents of nitrous salt. Despite the inconsistency, use of both methods to the same samples makes sense in reconstructions of climatic and environmental changes from lake sediments. In Lake Gouchi, the contents of nitrate and nitrite nitrogen vary from 1.40% in the lower part of the sequence to 14.77% in the uppermost part, suggesting a gradual evolution process from a fresh water lake to the present-day salt lake. 相似文献
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自动电位滴定仪具有操作简便、测定速度快的优势,减少了人为操作的影响,本文使用自动电位滴定仪测定海洋沉积物中有机碳的含量,并与国家标准(GB 17378.5—2007)中根据滴定过程中溶液颜色变化用肉眼判定滴定终点的方法进行了对比分析,确定通过仪器自动判断滴定终点实现准确测定的可行性。结果表明:自动电位滴定的方法检出限为0.029%,人工肉眼判定终点的方法检出限为0.086%,在滴定终点判定方面两种方法无显著性差异,但自动电位滴定仪的准确度和精密度更优,在一定程度上可代替肉眼判定滴定终点。实际应用过程中也发现,当滴定的溶液体系由于氧化还原反应、络合作用等影响因素使电位变化较为复杂时,自动电位滴定仪有可能会得到多个等当点而无法判断哪个等当点是真正的目标等当点,此时需要利用肉眼进行辅助确定。 相似文献
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土壤测汞方法在地球化学勘查中的应用 总被引:1,自引:0,他引:1
RG-1测汞仪具有抗干扰、精度高、检出限低、使用方便的优势.通过实例探讨了样品采集的层位、粒度、存放时间以及测试样品的条件等问题.多次反复试验工作证明了不同仪器应视其自身具体情况而决定测试条件.原子吸收热释法测汞,其样品的实际温度决定了汞的释出,而预热时间的长短决定了样品的实际温度.只有确保在所选取的各项试验条件下工作,才能使分析测试的结果达到标准要求.实践证明该方法在进行构造勘查方面的应用是行之有效的. 相似文献