Simultaneous control of nitrogen and phosphorus release from sediments using iron-modified zeolite as capping and amendment materials

Yanhui Zhan; Yang Yu; Jianwei Lin; Xiaolong Wu; Yan Wang; Yuying Zhao

doi:10.1016/j.jenvman.2019.109369

Simultaneous control of nitrogen and phosphorus release from sediments using iron-modified zeolite as capping and amendment materials

J Environ Manage. 2019 Nov 1:249:109369. doi: 10.1016/j.jenvman.2019.109369. Epub 2019 Aug 7.

Authors

Yanhui Zhan¹, Yang Yu¹, Jianwei Lin², Xiaolong Wu¹, Yan Wang¹, Yuying Zhao¹

Affiliations

¹ College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China.
² College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai, 201306, China. Electronic address: jwlin@shou.edu.cn.

PMID: 31400585
DOI: 10.1016/j.jenvman.2019.109369

Abstract

The use of zeolite as a geo-engineering tool has a high potential to control nitrogen (N) release from sediments, but its efficiency for controlling sedimentary phosphorus (P) release still need to be further increased. To address this issue, this work synthesized an iron-modified zeolite (IM-Z) by coating iron onto the surface of natural zeolite (NAT-Z) and then the as-obtained IM-Z was utilized as a geo-engineering material to block the upward mobilization of N and P from sediments to the overlying water. The efficiencies of IM-Z covering and amendment to prevent the liberation of N and P from sediments were evaluated, and the controlling mechanism was explored. Capping and amendment with IM-Z not only resulted in the tremendous reduction of the levels of ammonium-N (NH₄⁺-N) and reactive soluble P (RSP) in the overlying water, but also led to the decrease of the contents of NH₄⁺-N and RSP in the pore water. More importantly, sediment capping and amendment with IM-Z resulted in the formation of a static layer in the upper sediment directly below the sediment-water interface, with very low concentration of RSP in the pore water. In addition, IM-Z capping and addition effectively immobilized the diffusive gradients in thin films (DGT)-labile P in the overlying water and sediment. Furthermore, the decrease of the DGT-labile Fe concentrations in the overlying water as well as the top sediment were also observed after IM-Z capping and addition. Nearly 70% of P bound by IM-Z is stable and difficult to be released back into the overlying water under common pH and anoxic conditions. The adsorption of pore water NH₄⁺-N on IM-Z, the immobilization of pore water RSP and DGT-labile P by IM-Z and the uptake of DGT-labile Fe on IM-Z played a significant role in the simultaneous control of NH₄⁺-N and RSP liberation. Compared to NAT-Z, the efficiency of IM-Z to block the liberation of sedimentary P was higher. Results of this study demonstrate that IM-Z is suitable for use in the simultaneous interception of the upward transportation of NH₄⁺-N and RSP from sediments into the overlying water.

Keywords: Amendment; Capping; Iron-modified zeolite; Nitrogen; Phosphorus; Sediment.

MeSH terms

Geologic Sediments
Iron
Nitrogen
Phosphorus
Water Pollutants, Chemical*
Zeolites*

Substances

Water Pollutants, Chemical
Zeolites
Phosphorus
Iron
Nitrogen