Influence of recurrent rainfall and oxalic acid on phosphorus releasing from rocks phosphate in the Chaohu watershed, China. (January 2019)

• Record Type: Journal Article
• Authors: Qian, Jiazhong; Chu, Qiaoying; Zhang, Ruigang; Liu, Yong; Wan, Wenhua
• Is Part Of: Chemosphere. Volume 215(2019)
• Page Start: 815
• Page End: 826
• Publication Date: 2019-01
• Subjects: Phosphorus-rich rocks -- Phosphorus release -- Column leaching experiment -- Chaohu watershed; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.10.089
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In order to understand the spatial distribution characteristics, loss risk and leaching behaviors of phosphorous from exposed rocks in typical small-area of Chaohu watershed, phosphorus-rich rock was selected for conducting a series of column leaching experiments to investigate the phosphorus leaching. By simulating the intermittent cycle of acid rainfall, effects of oxalic acid on the weathering of phosphate rocks were studied. Total phosphorus contents, pH and phosphate leaching capacity from phosphorus rocks were tested in the presence of oxalic acid at different dry-wet intervals. The results indicated that the cumulative release of phosphorus increased first and then decreased with the duration of dry-wet intervals increasing. Four typical kinetic equations can describe phosphorus release from phosphate rocks with the action of oxalic acid. The best fitting models were the weight function and parabolic equation, with a mean correlation coefficient R 2 of 0.9727 and 0.9941, respectively, which reached significance level. Total phosphorus (TP) leaching distribution in each column showed a tendency of gradually decreasing from top to bottom except for time interval of 5 d and 7 d. Occluded-bound P (Oc-P) is the dominant form in rocks. The change point value of rocks phosphorus is 4.11 mg kg −1 after intermittent leaching, and the phosphorus loss risk is relatively large in some rocks formations. Highlights: A series of column leaching experiments were conducted for simulating acid rainfall at different time intervals. Characterization of the leachate variations in phosphate rocks with action of oxalic acid was studied. The cumulative release of phosphorus at different time intervals was investigated. Phosphorus leaching critical value was evaluated.