title: Notable increases in nutrient concentrations in a shallow lake during seasonal ice growth.
abstract: Nutrients may be eliminated from ice when liquid water is freezing, resulting in enhanced concentrations in the unfrozen water. The nutrients diluted from the ice may contribute to accumulated concentrations in sediment during winter and an increased risk of algae blooms during the following spring and summer. The objective of this study was to evaluate the influence of ice cover on nitrogen (N) and phosphorus (P) concentrations in the water and sediment of a shallow lake, through an examination of Ulansuhai Lake, northern China, from the period of open water to ice season in 2011-2013. The N and P concentrations were between two and five times higher, and between two and eight times higher, than in unfrozen lakes, respectively. As the ice thickness grew, contents of total N and total P showed C-shaped profiles in the ice, and were lower in the middle layer and higher in the bottom and surface layers. Most of the nutrients were released from the ice to liquid water. The results confirm that ice can cause the nutrient concentrations in water and sediment during winter to increase dramatically, thereby significantly impacting on processes in the water environment of shallow lakes.
authors.affiliation: Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018, China E-mail: nndlichangyou@163.com; Department of Physics, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Yang
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018, China E-mail: nndlichangyou@163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Changyou
authors.affiliation: Department of Physics, University of Helsinki, Helsinki 00014, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Leppäranta
authors.affiliation: Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018, China E-mail: nndlichangyou@163.com.
authors.forename: Shi
authors.initials: S
authors.lastname: Xiaonghong
authors.affiliation: Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, 306 Zhaowuda Road, Hohhot 010018, China E-mail: nndlichangyou@163.com.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Shengnan
authors.affiliation: Ecology and Environmental Science College, Inner Mongolia Agricultural University, Hohhot 010018, China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Chengfu
mesh_terms: D002681:China; D005068:Eutrophication; D019015:Geologic Sediments; D007053:Ice; D046448:Ice Cover; D060106:Lakes; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D012621:Seasons; D014867:Water; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D007053:Ice; D014874:Water Pollutants, Chemical; D014867:Water; D010758:Phosphorus; D009584:Nitrogen