Constructed wetlands （CWs） are engineered systems that utilize natural systems including wetland vegetations, soils, and their associated microbial assemblages to assist in treating wastewater. The kinetic adsorptio...Constructed wetlands （CWs） are engineered systems that utilize natural systems including wetland vegetations, soils, and their associated microbial assemblages to assist in treating wastewater. The kinetic adsorption of ammonium nitrogen （NH＋-N） by CW substrate materials such as blast furnace slag （BFS）, zeolite, ceramsite, vermiculite, gravel, paddy soil, red soil, and turf, was investigated using batch experiments and kinetic adsorption isotherms. Both Freundlich and Lang- muir isotherms could adequately predict the NH＋-N adsorption process. The maximum adsorption capacities of NH＋-N, estimated from the Langmuir isotherm, ranked as： zeolite （33 333.33 mg kg^-1） 〉 turf （29274.01 mg kg^-1） 〉 BFS （5000 mg kg^-1） 〉 vermiculite （3333.33 mg kg^-1） 〉 gravel （769.23 mg kg^-1） 〉 paddy soil （588.24 mg kg^-1） 〉 red soil （555.56 mg kg^-1） 〉 ceramsite （107.53 mg kg^-1）. Some properties of the substrate materials, including bulk density, specific gravity, hydraulic conductivity, uniformity coefficient （K60）, curvature coefficient （Co）, organic matter, pH, exchangeable （or active） Cu, Fe, Zn and Mn, total Cu, and Fe, Mn, Zn, Cd, Pb and Ca, had negative correlations with NH＋-N adsorption. Other properties of the substrate materials like particle diameter values of D10, 030 and 060 （the diameters of particle sizes of a substrate material at which 10%, 30% and 60%, respectively, of the particles pass through the sieve based on the accumulative frequency）, cation exchange capacity （CEC）, exchangeable （or active） Ca and Mg, and total K and Mg had positive correlations with NH＋-N adsorption. In addition, active K and Na as well as the total Na had significant positive correlations with NH＋-N adsorption. This information would be useful for selection of suitable substrate materials for CWs.展开更多
In recent years, excessive use of chemical nitrogen （N） fertilizers has resulted in the accumulation of excess ammonium （NH4＋） in many agricultural soils. Though rice is known as an NH4＋-tolerant species and can...In recent years, excessive use of chemical nitrogen （N） fertilizers has resulted in the accumulation of excess ammonium （NH4＋） in many agricultural soils. Though rice is known as an NH4＋-tolerant species and can directly absorb soil intact amino acids, we still know considerably less about the role of high exogenous NH4＋ content on rice uptake of soil amino acids. This experiment examined the effects of the exogenous NH4＋ concentration on rice uptake of soil adsorbed glycine in two different soils under sterile culture. Our data showed that the sorption capacity of glycine was closely related to soils＇ physical and chemical properties, such as organic matter and cation exchange capacity. Rice biomass was significantly inhibited by the exogenous NH4＋ content at different glycine adsorption concentrations. A three-way analysis of variance demonstrated that rice glycine uptake and glycine nutritional contribution were not related to its sorption capacity, but significantly related to its glycine：NH4＋ concentration ratio. After 21-d sterile cultivation, the rice uptake of adsorbed glycine accounted for 8.8%-22.6% of rice total N uptake, which indicates that soil adsorbed amino acids theoretically can serve as an important N source for plant growth in spite of a high NH4＋ application rate. However, further studies are needed to investigate the extent to which this bioavailability is realized in the field using the 13C, 15N double labeling technology.展开更多
基金Supported by the National Natural Science Foundation of China (Nos. 40871110 and 30828005)the National Water Pollution Control and Management Special Project of China (No. 2009ZX07102-003)+1 种基金the Special Project of Science and Technology of Guangdong Province,China (No. 2008A080800028)the Supporting Project of Science and Technology of Guangzhou City,China (No. 2008Z1-E621)
文摘Constructed wetlands （CWs） are engineered systems that utilize natural systems including wetland vegetations, soils, and their associated microbial assemblages to assist in treating wastewater. The kinetic adsorption of ammonium nitrogen （NH＋-N） by CW substrate materials such as blast furnace slag （BFS）, zeolite, ceramsite, vermiculite, gravel, paddy soil, red soil, and turf, was investigated using batch experiments and kinetic adsorption isotherms. Both Freundlich and Lang- muir isotherms could adequately predict the NH＋-N adsorption process. The maximum adsorption capacities of NH＋-N, estimated from the Langmuir isotherm, ranked as： zeolite （33 333.33 mg kg^-1） 〉 turf （29274.01 mg kg^-1） 〉 BFS （5000 mg kg^-1） 〉 vermiculite （3333.33 mg kg^-1） 〉 gravel （769.23 mg kg^-1） 〉 paddy soil （588.24 mg kg^-1） 〉 red soil （555.56 mg kg^-1） 〉 ceramsite （107.53 mg kg^-1）. Some properties of the substrate materials, including bulk density, specific gravity, hydraulic conductivity, uniformity coefficient （K60）, curvature coefficient （Co）, organic matter, pH, exchangeable （or active） Cu, Fe, Zn and Mn, total Cu, and Fe, Mn, Zn, Cd, Pb and Ca, had negative correlations with NH＋-N adsorption. Other properties of the substrate materials like particle diameter values of D10, 030 and 060 （the diameters of particle sizes of a substrate material at which 10%, 30% and 60%, respectively, of the particles pass through the sieve based on the accumulative frequency）, cation exchange capacity （CEC）, exchangeable （or active） Ca and Mg, and total K and Mg had positive correlations with NH＋-N adsorption. In addition, active K and Na as well as the total Na had significant positive correlations with NH＋-N adsorption. This information would be useful for selection of suitable substrate materials for CWs.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ15C130004)the National Basic Research Program(973)of China(No.2015CB150502)the National Natural Science Foundation of China(Nos.31172032 and 31270035)
文摘In recent years, excessive use of chemical nitrogen （N） fertilizers has resulted in the accumulation of excess ammonium （NH4＋） in many agricultural soils. Though rice is known as an NH4＋-tolerant species and can directly absorb soil intact amino acids, we still know considerably less about the role of high exogenous NH4＋ content on rice uptake of soil amino acids. This experiment examined the effects of the exogenous NH4＋ concentration on rice uptake of soil adsorbed glycine in two different soils under sterile culture. Our data showed that the sorption capacity of glycine was closely related to soils＇ physical and chemical properties, such as organic matter and cation exchange capacity. Rice biomass was significantly inhibited by the exogenous NH4＋ content at different glycine adsorption concentrations. A three-way analysis of variance demonstrated that rice glycine uptake and glycine nutritional contribution were not related to its sorption capacity, but significantly related to its glycine：NH4＋ concentration ratio. After 21-d sterile cultivation, the rice uptake of adsorbed glycine accounted for 8.8%-22.6% of rice total N uptake, which indicates that soil adsorbed amino acids theoretically can serve as an important N source for plant growth in spite of a high NH4＋ application rate. However, further studies are needed to investigate the extent to which this bioavailability is realized in the field using the 13C, 15N double labeling technology.
