title: Fluxes of nutrients and trace metals across the sediment-water interface controlled by sediment-capping agents: bentonite and sand.
abstract: The effect of bentonite and sand, as natural capping agents, on the fluxes of nutrients and trace metals across the sediment-water interface was studied through sediment incubation, and the ecotoxicological impact was assessed by using Daphnia magna. Bentonite and sand were layered on the sediment at 15, 75, and 225 mg cm(-2), and the concentration of cations, nutrients, and trace metals was measured. Sediment incubation showed that bentonite reduced the N flux but increased the P flux as a result of dissolution of non-crystalline P from bentonite, while sand slightly decreased the N fluxes but not the P flux. The concentration of Na increased in the overlying water with increasing application rates of bentonite, while that of Ca decreased. However, regardless of the rate of sand application, concentrations of all cation species remained unchanged. The concentration of As and Cr increased with bentonite application rate but decreased with sand. Both capping materials suppressed fluxes of Cd, Cu, Ni, and Zn compared to control, and the extent of suppression was different depending on the trace metal species and capping agents used. During sediment incubation, the survival rate of D. magna significantly decreased in bentonite suspension but began to decrease at the end in sand suspension. Sediment capping of mildly polluted sediments by using bentonite and sand lowered the level of nutrients and trace metals. However, unexpected or undesirable side effects, such as influxes of P and As from bentonite to the overlying water and a possibility of toxic impacts to aquatic ecosystems, were observed, suggesting that capping agents with an adequate assessment of their side effects and toxicity should be predetermined for site-specific sediment management strategies.
authors.affiliation: Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
authors.forename: Junho
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea. hmro@snu.ac.kr.
authors.forename: Hee-Myong
authors.identifier: http://orcid.org/0000-0001-5437-3484
authors.initials: HM
authors.lastname: Ro
authors.affiliation: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan, 44919, Republic of Korea.
authors.forename: Kyung Hwa
authors.initials: KH
authors.lastname: Cho
authors.affiliation: Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Gwangju, 61005, Republic of Korea.
authors.forename: Kyoung-Woong
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000818:Animals; D001546:Bentonite / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D003621:Daphnia / Q000187:drug effects*; D004784:Environmental Monitoring; D004787:Environmental Pollution; D019015:Geologic Sediments / Q000737:chemistry*; D008670:Metals / Q000032:analysis; D009584:Nitrogen / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry; D014131:Trace Elements / Q000032:analysis*; D014867:Water; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008670:Metals; D010710:Phosphates; D014131:Trace Elements; D014874:Water Pollutants, Chemical; D014867:Water; D001546:Bentonite; D012822:Silicon Dioxide; D012964:Sodium; D009584:Nitrogen; D002118:Calcium
keywords: Acute toxicity test; Bentonite; Nutrient; Sand; Sediment capping; Trace metal