| Measurement of the total nitrogen in lake sediments： Comparison and its environmental significance |
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| 作者姓名： | Wei JIANG Xinqing LEE |
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| 作者单位： | [1]State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry,, Chinese Academy of Sciences, Guiyang 550002, China [2]Graduate School of Chinese Academy of Sciences, Beijing 100039, China |
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| 摘 要： | 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.
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| 关 键 词： | 土壤 元素 氮循环 硝酸盐 湖泊 沉淀物 |
Sediment geochemical records of recent accelerated eutrophication in Wuli Bay of Taihu Lake, China |
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| Wei JIANG Xinqing LEE.Sediment geochemical records of recent accelerated eutrophication in Wuli Bay of Taihu Lake, China[J].Chinese Journal of Geochemistry,2006,25(B08):12-12. |
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| Abstract: | |
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| Keywords: | soil Kjeldahl method elemental analyzer nitrogen cycle nitrate |
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