1. State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology (Beijing),Beijing　 100083,China; 2. College of Ge-oscience and Surveying Engineering,China University of Mining and Technology (Beijing),Beijing　 100083,China; 3. Coal Center of China Energy Group, Beijing　 100011,China

The surface soil in eastern prairie open-pit mining area is poor and the grassland degradation is serious. Eco- logical restoration is inevitable. The surface soil of grassland mining area is insufficient,and the utilization of raw clay produced by open pit mining has become a feasible method for ecological restoration of mining area. Phosphorus is an essential nutrient element for plants and it is difficult to move in soil. The nutrient dynamics of phosphorus in different clay compositions has practical significance for rational utilization of clay. The adsorption and desorption of phosphorus on clay,surface soil,sandy soil,the mixture of clay and sandy soil in 1 ∶ 1 ratio ( NS1 ∶ 1),the mixture of clay and sandy soil in 1 ∶ 2 ratio (NS1 ∶ 2),and the mixture of clay and sandy soil in 1 ∶ 3 ratio ( NS1 ∶ 3) were compared and analyzed. It was found that the adsorption and desorption isotherms of phosphorus in clay were in accordance with Langmuir and Freundlich adsorption and desorption isotherms,and the maximum adsorption capacity (Γmax ) and maxmum buffer of phosphorus in clay were in accordance with Langmuir and Freundlich adsorption and desorption A- mount (MBC),equilibrium solution concentration (EPC0 ),phosphorus adsorption index (PSI),phosphorus saturation (DPS) and so on,all showed that the ability of fixing phosphorus element with clay and the mixture of clay and sand in 1 ∶ 1 ratio is stronger than surface soil,of which clay Γmax is 2. 61 times of surface soil,clay Γmax is 2. 21 times of surface soil. In the desorption process,the desorption rate of sandy soil is as high as 91% ,and the desorption amount is only 91. 3 mg / kg,the desorption rate of 1 ∶ 1 mixture of clay and sandy soil is 40. 4% and the desorption capacity is 395. 92 mg / kg,which is 1. 51 and 1. 29 times of that with surface soil and clay. The 1 ∶ 1 mixture of clay and sand showed the best effect in two aspects:phosphorus adsorption and phosphorus desorption.

国家重点研发计划资助项目(2016YFC0501106);国家自然科学基金资助项目(51574253)

SONG Ziheng,BI Yinli,ZHANG Jian,et al. Phosphorus dynamics of clay in Eastern grassland open pit mining area [J]. Journal of China Coal Society,2019,44(12):3807-3814.