Sediment potentially controls in-lake phosphorus cycling and harmful cyanobacteria in shallow, eutrophic Utah Lake

Abstract

Lakes worldwide are impacted by eutrophication and harmful algal or cyanobacteria blooms (HABs) due to excessive nutrients, including legacy P released from sediments in shallow lakes. Utah Lake (northern Utah, USA) is a shallow lake with urban development primarily on the east side of the watershed, providing an opportunity to evaluate HABs in relation to a gradient of legacy sediment P. In this study, we investigated sediment composition and P concentrations in sediment, pore water, and the water column in relation to blooms of harmful cyanobacteria species. Sediments on the east side of the lake had P concentrations up to 1710 mg/kg, corresponding to elevated P concentrations in pore water (up to 10.8 mg/L) and overlying water column (up to 1.7 mg/L). Sediment P concentrations were positively correlated with Fe 2 O 3 , CaO, and organic matter abundance, and inversely correlated with SiO 2 , demonstrating the importance of sediment composition for P sorption and mineral precipitation. Although the sediment contained <3% Fe 2 O 3 by weight, approximately half of the sediment P was associated with redox-sensitive Fe oxide/hydroxide minerals that could be released to the water column under reducing conditions. Cyanobacteria cell counts indicate that blooms of Aphanizomenon flos-aquae and Dolichospermum flosaquae species tend to occur on the east side of Utah Lake, corresponding to areas with elevated P concentrations in the sediment, pore water, and water column. Our findings suggest that shallow lake eutrophication may be a function of P in legacy sediments that contribute to observed HABs in specific locations of shallow lakes.

Predicting Nutrient Incontinence in the Anthropocene at Watershed Scales

“…One reason for our position that nutrient prevention should be prioritized over attenuation is simply the immense fertilization capacity of our global society (Gruber and Galloway, 2008;Seitzinger et al, 2010). The capacity of ecosystems to assimilate or remove N and P can easily be overwhelmed by human nutrient inputs, and recovery from nutrient saturation can take decades to millennia (Dupas et al, 2018;Goyette et al, 2018;Haas et al, 2019;Randall et al, 2019). This raises the question of how can nutrient inputs be decreased while also achieving the sustainable development goal of eliminating malnutrition?…”

“…There are three general fates for nutrients moving through the soils, riparian zones, surface waters, and aquifers of a watershed: (1) Retention (i.e., a long or short-term delay) by biological and physical processes, including nutrient uptake, sorption, or hydrological residence time (Covino et al, 2010;Sebilo et al, 2013;Van Meter et al, 2016;Dupas et al, 2017;Ehrhardt et al, 2019), (2) Vertical removal to the atmosphere or lithosphere, including denitrification, aeolian transport, or mineral precipitation with various metals (Groffman et al, 2006;Seitzinger et al, 2006;Pinay et al, 2018;Randall et al, 2019), and (3) Longitudinal export from the watershed via surface or subsurface flow (Burt and Pinay, 2005;Seitzinger et al, 2010;Abbott et al, 2018a). The reactivity and mobility of organic and inorganic nutrients depend on and influence biogeochemical conditions (Abbott et al, 2016;Bernhardt et al, 2017), meaning that the fate of carbon, N, and P can vary substantially through time (e.g., storm events or seasons) and in space (e.g., different watersheds or biomes) (Dupas et al, 2016;Moatar et al, 2017;Musolff et al, 2017;Minaudo et al, 2019).…”

Internal phosphorus loading due to sediment anoxia in shallow areas: implications for lake aeration treatments

“…In the current study, we found that IP pred is driven by PC3, a specific combination of five lake characteristics. Given the importance of sediment characteristics (Hupfer and Lewandowski 2008;Randall et al 2019), incorporating specific fractions (e.g., fractions that are commonly associated with the sediment P release, Fe content, Nürnberg 1988) may further increase the predictive power of the current model. Nevertheless, its current R 2 value was generally in a range of those that are reported for the models predicting release rates of P and internal P loading (Nürnberg et al 1986;Nürnberg 1988;Carter and Dzialowski 2012;Tammeorg et al 2017).…”

Proposal for Water Quality Improvement by Using an Innovative and Comprehensive Restoration Method

“…High phosphorus concentrations in the lake water persisted after the dairy sewage flow was stopped, which was due to permanent anoxia of the over-bottom water and consequently limited ability of the sediment to bind P. In the anoxic hypolimnion, 30% of the P can form complexes with iron, and another 30% can be incorporated into the phytoplankton biomass, while the remaining phosphorus is dissolved in water. Phosphates released by desorption and during organic matter decomposition in the bottom sediments have diffused toward the over-bottom water layer, and later to the trophogenic layer as a result of vertical transport [42][43][44]. In Miłkowskie Lake, despite high primary production (strong oxygen oversaturation in water, high pH, low water transparency, and high organic matter content), the total depletion of mineral phosphorus in the water was noted at the end of summer stagnation.…”