A multi-stable isotope framework to understand eutrophication in aquatic ecosystems

Abstract

10Eutrophication is a globally significant challenge facing aquatic ecosystems, associated with human 11 induced enrichment of these ecosystems with nitrogen (N) and phosphorus (P). However, the limited 12 availability of inherent labels for P and N has constrained understanding of the triggers for 13 eutrophication in natural ecosystems and appropriate targeting of management responses. This paper 14 proposes and evaluates a new multi-stable isotope framework that offers inherent labels to track 15 biogeochemical reactions governing both P and N in natural ecosystems. importance of abiotic and metabolic processes for the in-river fate of N and P are also explored 27 through the stable isotope framework. Microbial uptake of ammonium to meet metabolic demand for 28 N is suggested by substantial enrichment of δ 15 N NH4 (by 10.2‰ over a 100m reach) under summer 29 low flow conditions. Whilst the concentration of both nitrate and phosphate decreased substantially 30 along the same reach, the stable isotope composition of these ions did not vary significantly, 31indicating that concentration changes are likely driven by abiotic processes of dilution or sorption. 32The in-river stable isotope composition and the concentration of P and N were also largely constant 33 downstream of the waste water treatment works, indicating that effluent-derived nutrients were not 34 strongly coupled to metabolism along this in-river transect. Combined with in-situ and laboratory 35 hydrochemical data, we believe that a multi-stable isotope framework presents a powerful approach 36 for understanding and managing eutrophication in natural aquatic ecosystems. 37 38

Assessing Intra-Event Phosphorus Dynamics in Drainage Water Using Phosphate Stable Oxygen Isotopes

“…The 3.5‰ fluctuation of  18 O PO4-Drain within the monitored storm event was significant given the amount of variation in phosphate isotope signatures reported in previous studies. For example, Gooddy et al (2016) found that  18 O PO4 values over a 200 m stream reach with multiple source inputs, including a wastewater treatment plant and livestock farm, only varied by 2.0‰ to 2.8‰ during low flow and high flow sampling, respectively. Similarly, during a longitudinal river survey in southwest England, Granger et al (2017) found that  18 O PO4 signatures in tributaries and along the main stem of the river only varied by 1.7‰.…”

The Synergic Characteristics of Surface Water Pollution and Sediment Pollution with Heavy Metals in the Haihe River Basin, Northern China

“…A decline in water quality and the degradation of aquatic ecosystems are often accompanied by rapid agricultural and economic development [1][2][3]. Eutrophication, as an important contributor to the degradation of aquatic ecosystems, is the enrichment of water bodies by nutrients, especially compounds of nitrogen (N) and phosphorus (P), which may cause the accelerated growth of algae and higher forms of plant life and produce an undesirable disturbance to the balance of organisms and water quality [4].…”

“…The objectives of this study are to: (1) assess the water quality and potential ecological risk of heavy metals in the Haihe River Basin; (2) explore and understand the synergic pollution characteristics of surface water quality and heavy metal pollution in sediments; and (3) identify the driving forces that cause eutrophication, the potential ecological risk of heavy metals and their synergic pollution in the Haihe River Basin.…”

Modélisation de l'évolution spatiotemporelle du phosphore minéral dans une baie lagunaire hypereutrophe tropicale : la baie lagunaire de Tiagba (Côte d'Ivoire)

“…Si le phosphore constitue l'un des éléments nutritifs majeurs pour les écosystèmes aquatiques, il n'en demeure pas moins que sa présence excessive dans ces entités est l'une des causes principales de l'eutrophisation. Dans ce fléau écologique, il est incriminé en tant que cofacteur limitant avec l'azote (GOODY et al, 2016;KASPERSEN et al, 2016;ROLLAND et al, 2015;ULRICH et al, 2016). Il en est le facteur de maîtrise du fait de son cycle biogéochimique (ABEL et al, 2010;YAO, 2011).…”