title: Phosphorus fluxes at the sediment-water interface in subtropical wetlands subjected to experimental warming: a microcosm study.
abstract: Global warming is increasingly challenging for wetland ecological function. A temperature controlled microcosm system was developed to simulate climate change scenarios of an ambient temperature (control) and an elevated temperature (+5 °C). The effects and associated mechanisms of warming on phosphorus (P) fluxes at the sediment-water interface of six subtropical wetlands were investigated. The results indicated that P fluxes were generally enhanced under the experimental warming as measured by higher P concentrations in the porewater and overlying water as well as higher benthic P fluxes. The release of P from sediment to porewater occurred more strongly and quickly in response to experimental warming compared to the subsequent upward transfer into overlying water. The average accumulative benthic P output from the tested wetlands under the experimental warming was greater by 12.9 μg cm(-2) y(-1) (28%) for total P and 8.26 μg cm(-2) y(-1) (25%) for dissolved reactive P, compared to the ambient scenarios. Under warming the redistribution of P fractions in sediments occurred with greater NH(4)Cl-P and lower BD-P (extracted by a bicarbonate buffered dithionite solution) accompanied by greater NaOH-P. The higher temperature enhanced total phospholipid fatty acids. A shift in the microbial community was also observed with a relative dominance of fungi (a 4.7% increase) and a relative decline (by 18%) in bacterial abundance, leading to the higher secretion of phosphatase. Comparing between wetlands, the potential P fluxes in the nutrient-enriched wetlands were less impacted by warming than the other wetland types investigated. Thus wetlands characterized by low or medium concentrations of P in sediments were more susceptible to warming compared to P-rich wetlands.
authors.affiliation: College of Environmental and Resource Sciences, China Academy of West Region Development, ZheJiang University, Yuhangtang Avenue 688, HangZhou, ZheJiang Province 310058, China.
authors.forename: Hang
authors.initials: H
authors.lastname: Wang
authors.forename: Joseph
authors.initials: J
authors.lastname: Holden
authors.forename: Kandice
authors.initials: K
authors.lastname: Spera
authors.forename: XinHua
authors.initials: X
authors.lastname: Xu
authors.forename: ZaoDe
authors.initials: Z
authors.lastname: Wang
authors.forename: JingHua
authors.initials: J
authors.lastname: Luan
authors.forename: Xin
authors.initials: X
authors.lastname: Xu
authors.forename: ZhiJian
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D017753:Ecosystem; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus