选择东北典型黑土区--德惠市、扶余市和双城市为研究区,利用便携式地物光谱仪获取土壤光谱数据,基于原始光谱值及一阶微分、倒数的对数、连续统去除变换,分别建立了黑土有机质含量的多元线性逐步回归模型、偏最小二乘回归模型和BP神经...选择东北典型黑土区--德惠市、扶余市和双城市为研究区,利用便携式地物光谱仪获取土壤光谱数据,基于原始光谱值及一阶微分、倒数的对数、连续统去除变换,分别建立了黑土有机质含量的多元线性逐步回归模型、偏最小二乘回归模型和BP神经网络模型。结果表明:高光谱与土壤有机质含量在多个波段相关性较好,其中有机质与反射率一阶微分处理的相关性最好,在光谱584 nm处其相关性最强(r=-0.60,n=81)。光谱一阶微分处理数据在三种建模方法中的预测及验证精度均高于原始光谱值、倒数的对数和连续统去除变换,因此一阶微分为最佳光谱变换形式。偏最小二乘回归分析的预测效果整体优于多元线性逐步回归分析和BP神经网络分析,光谱一阶微分处理的偏最小二乘回归模型呈现出最佳预测效果,决定系数为0.71、均方根误差为2.29 g kg^-1(n=53)。展开更多
The mobility and bioavailability of selenium is a major health and environmental issue and a main concern for geological disposal of high-level radioactive waste. Chemically and/or microbially mediated oxidation of in...The mobility and bioavailability of selenium is a major health and environmental issue and a main concern for geological disposal of high-level radioactive waste. Chemically and/or microbially mediated oxidation of insoluble Se-bearing particulate, such as iron selenides, to dissolved and mobile phases controls the transport and distribution of Se in the environment. The oxidation of ferroselite （FeSe2） by ferric iron was investigated in anoxic conditions. The redox reaction can be represented by： FeSe2 ＋ 2Fe3＋ = 2Se^0 ＋ 3Fe2＋. Kinetic studies indicated that the reaction can be described by second-order rate law, with rate constants of 0.49±0.01, 0.85±0.02, 1.84±0.04, and 3.29±0.13 L mol^-1 s^-1 at pH 1.62, 1.87, 2.23, and 2.49, respectively. The positive correlation between reaction rate and pH implies that diffusion of Fe3＋ oxidant to the mineral surface is the rate-determining step. The strong reactivity of FeSe2 towards Fe^3＋ suggests that ferric iron may play a significant role in FeSe2 oxidation process （e.g., by Se^4＋, 02, etc.） and Se^0 should be the first reaction product. Also, it was shown that the reduction rate of Fe^3＋ or Se^4＋ by pyrite （FeS2） can be significantly increased in the presence of FeSe2, suggesting a stronger reactivity of FeSe2 compared with pyrite. The results obtained extend our knowledge about the subtle interaction between Se, pyrite and iron selenides in the environment, and give insight into the transfer of selenium from iron selenides to bio-available selenium （i.e., selenite and selenate） in the Se-rich environment.展开更多
文摘选择东北典型黑土区--德惠市、扶余市和双城市为研究区,利用便携式地物光谱仪获取土壤光谱数据,基于原始光谱值及一阶微分、倒数的对数、连续统去除变换,分别建立了黑土有机质含量的多元线性逐步回归模型、偏最小二乘回归模型和BP神经网络模型。结果表明:高光谱与土壤有机质含量在多个波段相关性较好,其中有机质与反射率一阶微分处理的相关性最好,在光谱584 nm处其相关性最强(r=-0.60,n=81)。光谱一阶微分处理数据在三种建模方法中的预测及验证精度均高于原始光谱值、倒数的对数和连续统去除变换,因此一阶微分为最佳光谱变换形式。偏最小二乘回归分析的预测效果整体优于多元线性逐步回归分析和BP神经网络分析,光谱一阶微分处理的偏最小二乘回归模型呈现出最佳预测效果,决定系数为0.71、均方根误差为2.29 g kg^-1(n=53)。
基金supported by the Special Foundation for High-Level Radioactive Waste Disposal(2007-840,2012-851)the National Natural Science Foundation of China(11075006,91026010)+1 种基金the China Postdoctoral Science Foundation Project(2013M530013)the Collaborative Project from the Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences(KLMM20120203)
文摘The mobility and bioavailability of selenium is a major health and environmental issue and a main concern for geological disposal of high-level radioactive waste. Chemically and/or microbially mediated oxidation of insoluble Se-bearing particulate, such as iron selenides, to dissolved and mobile phases controls the transport and distribution of Se in the environment. The oxidation of ferroselite （FeSe2） by ferric iron was investigated in anoxic conditions. The redox reaction can be represented by： FeSe2 ＋ 2Fe3＋ = 2Se^0 ＋ 3Fe2＋. Kinetic studies indicated that the reaction can be described by second-order rate law, with rate constants of 0.49±0.01, 0.85±0.02, 1.84±0.04, and 3.29±0.13 L mol^-1 s^-1 at pH 1.62, 1.87, 2.23, and 2.49, respectively. The positive correlation between reaction rate and pH implies that diffusion of Fe3＋ oxidant to the mineral surface is the rate-determining step. The strong reactivity of FeSe2 towards Fe^3＋ suggests that ferric iron may play a significant role in FeSe2 oxidation process （e.g., by Se^4＋, 02, etc.） and Se^0 should be the first reaction product. Also, it was shown that the reduction rate of Fe^3＋ or Se^4＋ by pyrite （FeS2） can be significantly increased in the presence of FeSe2, suggesting a stronger reactivity of FeSe2 compared with pyrite. The results obtained extend our knowledge about the subtle interaction between Se, pyrite and iron selenides in the environment, and give insight into the transfer of selenium from iron selenides to bio-available selenium （i.e., selenite and selenate） in the Se-rich environment.
