Different provenance of separate loess sites in Yangtze River Basin and its paleoenvironmental implications

The dust deposits in the Yangtze River Basin(YRB)have been widely distributed along the Yangtze River valley.Previous studies mainly concentrated in its provenance of each loess site,however,the differences in provenance of loess among different sites in this area have rarely been studied.Here,the geochemical characteristics of the<20μm fraction in the loess in separate Jiujiang,Xuancheng and Nanjing sites were analyzed.The result shows that the loess in Jiujiang and Nanjing sites,near Yangtze River riverway,share similar geochemical characteristics that may commonly derived from the detrital materials of Yangtze River.However,both sites have significantly different elemental compositions compared with Xuancheng site,which is^60 km away from the Yangtze River riverway.These sites share different geochemical characteristics with Eastern Qinling Mountains and Xifeng section on the Chinese Loess Plateau,North China.Combining the distribution of the aeolian sand hills and the loess in this area published by previous studies,we suggest that the exposed river valley floodplain caused by weak summer monsoon provided abundant materials to form local dust cells controlled by strong winter monsoon during the glacial periods.Therefore,those local loess deposits should be identified as the“valley-sourced loess”.These reveal the inherent connection between the monsoon system and the loess deposits in Yangtze River Basin.

PREPARATION AND CHARACTERIZATION OF NOVEL CHITOSAN DERIVATIVES:ADSORPTION EQUILIBRIUM OF IRON(Ⅲ) ION

The adsorption of Fe(Ⅲ)ions from aqueous solution by chitosan alpha-ketoglutaric acid(KCTS)and hydroxamated chitosan alpha-ketoglutaric acid(HKCTS)was studied in a batch adsorption system.Experiments were carried out as function of pH,temperature,agitation rate and concentration of Fe(Ⅲ)ions.The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and isotherm constants were determined.The Langmuir model agrees very well with experimental data.The pseudo-first-order a...