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1.
电感耦合等离子体质谱法同时测定地下水中硼溴碘 总被引:6,自引:4,他引:2
建立了电感耦合等离子体质谱法同时测定地下水中B、Br、I的方法。选定φ=2%(体积分数)的稀NH3.H2O介质消除碘的记忆效应。采用干扰较少的10B和79Br同位素。B、Br、I在0~10 000 ng/mL呈良好的线性关系。方法的检出限为10B 0.176 ng/mL,79Br 0.876ng/mL,127I 0.132 ng/mL;精密度(RSD,n=12)为10B 2.86%,79Br 3.36%,127I 2.69%;10B的阶梯加标回收率为94.6%~101.5%,79Br为98.3%~104.9%,127I为96.5%~102.0%。 相似文献
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不同氮源对微小亚历山大藻生长和毒素产生的影响 总被引:12,自引:0,他引:12
通过尿素、氯化铵、酵母浸出粉和硝酸钠等氮源对微小亚历山大藻(Alexandrium minutum)生长及毒素产生的影响研究,分析了微小亚历山大藻对不同氮源利用状况的差异.结果表明,在氮饥饿条件下,加入硝酸钠和酵母浸出粉能显著促进微小亚历山大藻的生长;高浓度的氯化铵在加入后对微小亚历山大藻有一定的毒性效应,表现为生长停滞,但毒性效应在5 d后消失,并得到与添加硝酸钠及酵母浸出粉相似的增长速率0.21 d-1;添加尿素对微小亚历山大藻的生长没有显著促进作用.在四种氮源中,尿素对微小亚历山大藻毒素产生的刺激作用也最弱,在稳定期每个细胞藻细胞毒素含量维持在6.00~8.00 fmol;添加硝酸钠、氯化铵和酵母浸出粉的藻细胞在稳定期毒素含量分别达到11.85,12.86和14.64 fmol.硝酸钠和氯化铵刺激藻毒素产生的效果比酵母浸出粉更为直接.四种含氮营养盐对微小亚历山大藻毒素组成的影响都很小. 相似文献
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Martin Rosner Michael Wiedenbeck Thomas Ludwig 《Geostandards and Geoanalytical Research》2008,32(1):27-38
An analytical artefact is reported here related to differences in instrumental mass fractionation between NIST SRM glasses and natural geological glasses during SIMS boron isotope determinations. The data presented demonstrated an average 3.4‰ difference between the NIST glasses and natural basaltic to rhyolitic glasses mainly in terms of their sputtering-induced fractionation of boron isotopes. As no matrix effect was found among basaltic to rhyolitic glasses, instrumental mass fractionation of most natural glass samples can be corrected by using appropriate glass reference materials. In order to confirm the existence of the compositionally induced variations in boron SIMS instrumental mass bias, the observed offset in SIMS instrumental mass bias has been independently reproduced in two laboratories and the phenomenon has been found to be stable over a period of more than one year. This study highlights the need for a close match between the chemical composition of the reference material and the samples being investigated. 相似文献
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Wei ZHANG Congqiang LIU Zhiqi ZHAO 《中国地球化学学报》2006,25(B08):172-172
Boron has two stable isotopes (^10B and ^11B) with relative abundances of about 20% and 80%, respectively. Boron isotopic ratios in natural materials show a huge range of variations, from -70‰ to +60‰, when expressed with the classical δ^11B notation. Most of these isotopic variations occur at the surface of the Earth. Hence, boron isotopic composition can be used as a sensitive tracer in geochemical study, for instance, to identify the different sources of contamination and factors controlling the salinity of groundwater. During the last decade, boron isotopes have been used to discriminate between the influences of seawater intrusion and anthropogenic discharge. But few of those researches can precisely identify the different sources of contamination. We measured the boron concentrations and boron isotopic ratios of groundwater samples collected in Guiyang City, as well as the major ions. The results indicate that the major ion composition of the groundwater in the investigated area is mainly controlled by the interactions between water and the dominant rock i.e. carbonates. All the water compositions are characterized by high concentrations of Ca^2+, Mg^2+, HCO3^-, SO4^2-, and NO3^-, which are the dominant contaminants. Both dissolved boron concentrations and isotopic ratios show large variations among the ground waters, from 2 μg/L to 90 μg/L and from -6‰ to +26‰, respectively. The boron concentrations and isotopic ratios indicate that the river across the studied city has been seriously contaminated by urban discharge. Boron concentrations of fiver water samples varied from 20 μg/L to 140 μg/L, with an average δ^11B value of +2.0‰. Using boron isotopic compositions and different geochemical indices allowed us to clearly identify and distinguish the two major sources of contamination, agricultural activity and urban wastewater. Both of the two sources are characterized by high boron concentrations but their boron isotopic compositions significantly differ. 相似文献
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The chronological data obtained by a variety of dating methods have confirmed that the sodium enriched metavolcanite series
in the area of the Longbohe copper deposit at Jinping, Yunnan Province, was formed during the Proterozoic (its Pb−Pb isochron
age=1595±75 Ma), corresponding to the Dahongshan Group sodium enriched metavolcanites. The Sm−Nd isochron age of 1336±46Ma
should represent the time at which this series of volcanic rocks experienced spilitization in response to sodium metasomatism,
equivalent to the time of sedimentation of the Ailaoshan Group and Yashan Group rocks. The Rb−Sr ages of the volcanic rocks
and the Pb−Pb ages of copper ores have recorded the events of strong dynamic metamorphism and of strong reworking-metallogenesis
of copper during the Jinningian period. Similarities in forming age, rock assemblage and isotopic characteristics between
the sodium enriched metavolcanite series and the Dahongshan Group sodium enriched metavolcanite series have provided new clues
to the exploration of the Dahongshan-type copper deposits in this area.
Granted jointly by the National Natural Science Foundation of China (Nos. 49702022, 40073001) and the State 973 Program (No.
G1999043215). 相似文献
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