钼锑抗分光光度法对黄河表层沉积物中磷的形态分布及其吸附-解吸特征研究
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摘要
采用标准测试程序(SMT)和钼锑抗分光光度法对黄河流域甘宁蒙段表层沉积物进行磷形态的提取和含量测定,同时模拟沉积物对磷吸附-解吸特性进行了探索。结果表明:对照不同的评价标准,12个采样点中总磷(TP)含量均处于不同程度的污染水平,特别是S12采样点磷具有较高的释放风险。TP、无机磷(IP)和钙结合态磷(HCl-P)之间及有机磷(OP)和铁/铝结合态磷(NaOH-P)之间分别呈现出较好的正相关性。沉积物的组成和理化性质对磷的赋存形态产生影响,OP和NaOH-P可能与As,Ni,Co和Pb有相同的污染源。表层沉积物对磷的吸附-解吸过程均符合伪二级动力学方程,主要受化学作用的控制,而磷的等温吸附符合Langmuir方程,且升高温度有利于磷的吸附。水相中离子浓度(KCl)小于0.02mol·L-1时,吸附作用占优势,反之,解吸作用占优势。水土比的增大会提高沉积物对磷的吸附量。另外,磷的解吸量会随着温度的升高和扰动强度的增加而增大。揭示了黄河甘宁蒙段表层沉积物中磷的形态分布及其吸附–解吸特征,为黄河甘宁蒙段水环境治理和磷负荷调控提供依据。
In order to study the distribution on phosphorus fractions and adsorption-desorption characteristics in surface sediments from Gansu,Ningxia and Inner Mongolia sections of the Yellow River,the methods of standards measurements and testing(SMT)and molybdenum antimony spectrophotometry were chosen to extract phosphorus fractions and measure contents,respectively.The assays of adsorption-desorption characteristics on phosphorus were carried simultaneously.The results were as follows:Compared with the different evaluation criteria,the contents of TP in all sampling sites were in different levels of pollution.Especially at S12 sampling site,a high release risk of phosphorus was existed.There were better positive correlations among TP,IP and HCl-P as well as between OP and NaOH-P.Composition and physicochemical properties of surface sediments had effects on various fractions of phosphorus,OP and NaOH-P were likely to have the same sources of pollution with As,Ni,Co and Pb.The adsorption-desorption processes of phosphorus were in accord with the pseudo-second-order kinetics,which suggested the processes were mainly controlled by chemistry.The isothermal adsorption of phosphorus was also in accord with the Langmuir equation,and the adsorbent contents of phosphorus were incremental with the rise of temperature.When the concentrations of KCl in aqueous phase were less than 0.02 mol·L-1,the adsorption process of phosphorus was predominant;conversely,the desorption process was dominant.The increase of water-soil ratios improved the adsorptive capacity of phosphorus.The rise of temperature and intensity of disturbance would improve desorption of phosphorus.The study revealed the distribution of phosphorus fractions and adsorption-desorption characteristics in surface sediments,providing bases for treatment of water environment and regulation of phosphorus load in Gansu,Ningxia and Inner Mongolia sections of the Yellow River.
In order to study the distribution on phosphorus fractions and adsorption-desorption characteristics in surface sediments from Gansu,Ningxia and Inner Mongolia sections of the Yellow River,the methods of standards measurements and testing(SMT)and molybdenum antimony spectrophotometry were chosen to extract phosphorus fractions and measure contents,respectively.The assays of adsorption-desorption characteristics on phosphorus were carried simultaneously.The results were as follows:Compared with the different evaluation criteria,the contents of TP in all sampling sites were in different levels of pollution.Especially at S12 sampling site,a high release risk of phosphorus was existed.There were better positive correlations among TP,IP and HCl-P as well as between OP and NaOH-P.Composition and physicochemical properties of surface sediments had effects on various fractions of phosphorus,OP and NaOH-P were likely to have the same sources of pollution with As,Ni,Co and Pb.The adsorption-desorption processes of phosphorus were in accord with the pseudo-second-order kinetics,which suggested the processes were mainly controlled by chemistry.The isothermal adsorption of phosphorus was also in accord with the Langmuir equation,and the adsorbent contents of phosphorus were incremental with the rise of temperature.When the concentrations of KCl in aqueous phase were less than 0.02 mol·L-1,the adsorption process of phosphorus was predominant;conversely,the desorption process was dominant.The increase of water-soil ratios improved the adsorptive capacity of phosphorus.The rise of temperature and intensity of disturbance would improve desorption of phosphorus.The study revealed the distribution of phosphorus fractions and adsorption-desorption characteristics in surface sediments,providing bases for treatment of water environment and regulation of phosphorus load in Gansu,Ningxia and Inner Mongolia sections of the Yellow River.
引文
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