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Distribution of total,exchangeable and fixed nitrogen in the sediments from shallow lakes in the middle and lower reaches of the Yangtze River

摘要：研究了长江中下游浅水湖泊沉积物总氮、可交换态氮与固定态铵的赋存特征.结果表明:①14个沉积物的总氮(TN)含量为768.5～5190.6mg·kg^-1之间,以月湖沉积物TN含量最高,是其它各湖泊沉积物TN含量的2～7倍;可交换态氮(EN)含量为150.92～341.98mg.kg^-1,占TN的6.29%～19.64%;固定态铵(F-NH₄)含量变化在186.5～462.5mg·kg^-1,占TN的8.40%～35.02%.②EN以NH₄⁺-N为主,NO₃^--N其次,NO₂^--N最低,分别占EN的74.61%～85.85%、13.93%～25.15%和0.17%～0.27%.③EN、NH₄⁺-N、NO₃^--N及NO₂^--N之间在α=0.01时互为显著正相关,F-NH₄与EN、NH₄⁺-N在α=0.05时显著正相关,而与NO₃^--N、NO₂^--N不相关.④在α=0.01或α=0.05时,EN、NH₄⁺-N、NO₃^--N、NO₂^--N和F-NH₄分别与总氮(TN)、总磷(TP)、有机碳(TOC)、阳离子代换量(CEC)、粉沙粒(Silt)及粘粒(Clay)含量有显著正相关关系,与粗砂粒(Sand)含量有显著负相关关系.除此之外,F-NH₄与CaO、Fe₂O₃和Al₂O₃均有显著正相关关系.

Abstract：Distribution of total nitrogen(TN),exchangeable nitrogen(EN)and fixed ammonium(F-NH₄)and their functions in recycling in sediments from shallow lakes in the middle and lower reaches of the Yangtze River were investigated.The results indicated that:① Contents of TN,ENand F-NH₄ of 14 lake sediment samples of the studied region were 768.5～5190.6 mg·kg^-1,150.92～341.98 mg·kg^-1 and 186.5～462.5 mg·kg^-1,respectively.② Exchangeable nitrogen,NH₄⁺-N,NO₃^--Nand NO₂^--Nwere 150.92～341.98mg·kg^-1,145.2～269.4 mg·kg^-1,30.3～71.8 mg·kg^-1,and 0.32～0.78 mg·kg^-1,accounting for 74.61%～85.85%,13.93%～25.15% and 0.17%～0.27% of total exchangeable-Nitrogen,respectively.③ Exchangeable NH₄⁺-N,NO₃^--N and NO₂^--N have remarkable positive correlations among them.There is a strong positive correlation between exchangeable ammonium and fixed ammonium.④ The exchangeable and fixed nitrogen have strong positive correlations with the contents of TN,TP,TOC,CEC,silt and clay of the studied samples,but have strong negative correlations with sand content.In addition,there are positive correlations between the contents of CaO,Fe₂O₃ and Al₂O₃ and fixed ammonium.