title: Effect of water quality improvement on the remediation of river sediment due to the addition of calcium nitrate.
abstract: In situ sediment remediation technique is commonly used to control the release of pollutants from sediment. Addition of calcium nitrate to sediment has been applied to control the release of phosphorus from sediments. In this study, laboratory experiments were conducted to investigate the effect of water quality improvement on the remediation of river sediment with the addition of calcium nitrate. The results demonstrated that the redox-potential of sediments increased from -282mV to -130mV after 28days of calcium nitrate treatment. The acid volatile sulphide in the sediments significantly decreased (by 54.9% to 57.1%), whereas the total organic carbon decreased by 9.7% to 10.2%. However, the difference between these and water quality improvement was not significant. Due to the addition of calcium nitrate, low phosphate concentration in the water column and interstitial phosphate in the sediment were observed, indicating that the calcium nitrate was beneficial to controlling the release of phosphorus from river sediment. The decrease in phosphorus release could be attributed to the fixation of iron-phosphorus and calcium-phosphorus due to the addition of calcium nitrate. The addition of calcium nitrate to sediment caused the oxidation of sulphide to sulphate, hence resulting in high nitrate and sulphate concentrations in the water column, and high interstitial nitrate and sulphate concentrations in the sediment. The results also showed that only the water quality improvement had a significant effect on the interstitial nitrate and sulphate concentrations in the sediment.
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Tsinghua-Kangda Research Institute of Environmental Nano-Engineering & Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Tsinghua-Kangda Research Institute of Environmental Nano-Engineering & Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China. Electronic address: tao.yi@sz.tsinghua.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Tao
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Kuiyu
authors.initials: K
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Qiqi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Guangyao
authors.initials: G
authors.lastname: Chen
authors.affiliation: Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; Tsinghua-Kangda Research Institute of Environmental Nano-Engineering & Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
authors.forename: Xihui
authors.initials: X
authors.lastname: Zhang
keywords: Acid volatile sulphide; Calcium nitrate; Phosphorus; Sediment; Total organic carbon; Water quality