Seasonal variation in the mineralogy of the suspended particulate matter of the lower Changjiang river at Nanjing, China
Mao, Changping (Nanjing University. Department of Earth Sciences.)
Chen, Jun (Nanjing University. Department of Earth Sciences)
Yuan, Xuyin (Hohai University. College of Environmental Science and Engineering)
Yang, Zhongfang (China University of Geosciences. School of Earth Science and Resources)
Balsam, William (University of Texas at Arlington)
Ji, Junfeng (Nanjing University. Department of Earth Sciences)

Data:	2010
Resum:	The source and temporal changes of minerals transported by the world's large rivers are important. In particular, clay minerals are important in evaluating the maturity of suspended sediments, weathering intensity, and source area. To examine seasonal changes in mineralogical compositions of the Changjiang River (CR), suspended particulate matter (SPM) samples were collected monthly for two hydrological cycles in Nanjing city and then were studied using X-ray diffraction (XRD), diffuse reflectance spectrophotometry (DRS), X-ray fluorescence spectrometry (XRF), and chemical analyses. The resultsindicate that the concentration of CR SPM rangesfrom 11. 3 to 152 mg/L and ishighly correlated to the rate of water discharge, with a greater concentration in flood season and lower concentrations during the dry season. CaO, MgO, and NaO increase with increasing discharge whereas AlO decreases sharply with increasing discharge. Dolomite, calcite, and plagioclase show strikingly similar seasonal variations and increase with increasing discharge with maximum concentrations in the flood season. In contrast, the clay mineral content exhibits the opposite trend with the lowest concentrationsin the flood season. Illite dominatest he clay mineralsof the CR SPM, followed by chlorite, kaolinite, and smectite. Illite and kaolinite show distinctly seasonal variations; SPM contains more illite and less kaolinite during the flood season than during the dry season. The illite chemistry index and crystallinity, as well as kaolinite/illite ratio, all indicate intense physical erosion in the CR basin during the rainy season. Total iron (Fe) and highly reactive iron (Fe) concentrations display slight seasonal changes with the smallest values observed during the flood season. Goethite is the dominant Fe oxide mineral phase in the CR SPM and hematite is a minor component, as revealed by DRS analyses. The FeT flux and FeHR flux are 2. 78×10 T/y and 1. 19×10 T/y, respectively.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Changjiang River ; Erosion ; Mineralogy ; Seasonality ; Suspended Particulate Matter
Publicat a:	Clays and Clay Minerals, Vol. 58, Núm. 5 (2010) , p. 691-706, ISSN 1552-8367

DOI: 10.1346/CCMN.2010.0580508

16 p, 1.5 MB  Accés restringit a la UAB

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