Differential influence of landscape features and climate on nitrogen and phosphorus transport throughout the watershed

Goyette, Jean-Olivier; Bennett, Elena M.; Maranger, Roxane

doi:10.1007/s10533-018-0526-y

Cited by 47 publications

(39 citation statements)

References 80 publications

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“…Thus, these paired inventories can inform recommendations on coordinating and spatially prioritizing water and air quality restoration efforts (Palmer & Filoso, 2009). While developing consistent inventories is helpful in grasping current impacts on the P cycle, estimating the regional variability of agricultural legacy P pools across the CONUS using standardized methods is also needed to evaluate the potential efficacy of management actions and changing precipitation patterns on hydrologic phosphorus export (Chen et al, 2018;Goyette et al, 2019;Sinha et al, 2017). For both P and N, the rate of nutrient inputs and/or surplus, which is the remaining N or P left in the land after accounting for inputs and losses, has been found to largely explain the spatiotemporal variability in nutrient export (Goyette et al, 2016;Goyette et al, 2019;Hong et al, 2017;Sinha & Michalak, 2016).…”

Section: Introductionmentioning

confidence: 99%

Phosphorus Inventory for the Conterminous United States (2002–2012)

et al. 2021

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Published reports suggest efforts designed to prevent the occurrence of harmful algal blooms and hypoxia by reducing non-point and point source phosphorus (P) pollution are not delivering water quality improvements in many areas. Part of the uncertainty in evaluating watershed responses to management practices is the lack of standardized estimates of phosphorus inputs and outputs. To assess P trends across the conterminous United States, we compiled an inventory using publicly available datasets of agricultural P fluxes, atmospheric P deposition, human P demand and waste, and point source discharges for 2002, 2007, and 2012 at the scale of the 8-digit Hydrologic Unit Code subbasin (∼1,800 km 2 ). Estimates of agricultural legacy P surplus accumulated from 1945 to 2001 were also developed. Fertilizer and manure inputs were found to exceed crop removal rates by up to 50% in many agricultural regions. This excess in inputs has led to the continued accumulation of legacy P in agricultural lands. Atmospheric P deposition increased throughout the Rockies, potentially contributing to reported increases in surface water P concentrations in undisturbed watersheds. In some urban areas, P fluxes associated with human waste and non-farm fertilizer use has declined despite population growth, likely due, in part, to various sales bans on P-containing detergents and fertilizers. Although regions and individual subbasins have different contemporary and legacy P sources, a standardized method of accounting for large and small fluxes and ready to use inventory numbers provide essential infromation to coordinate targeted interventions to reduce P concentrations in the nation's waters. Plain Language Summary Excessive phosphorus (P) concentrations in surface waterendanger public health and welfare by contributing to harmful algal blooms and hypoxic zones. Many efforts to decrease P pollution to the nation's waters have not achieved desired outcomes. To help decisionmakers develop strategies to decrease P loads, we developed an inventory of inputs and outputs of P across the United States. This inventory reveals the source and magnitude of P in a local area and how it changes through time. We found that agricultural P inputs were the largest source of P nationwide and inefficiencies in use contribute to the continued accumulation of phosphorus across the landscape. This excess phosphorus may make it more difficult to achieve water quality goals. However, many agricultural regions in the eastern and western United States demonstrated more efficient use of phosphorus fertilizer in 2012. On another positive note, urban areas in certain regions have likely decreased their fertilizer application rates, the amount of P being released by detergents, and point source loads. These efforts may have contributed to recent reports of improved water quality in more urbanized watersheds. Decision makers should consider the role of current fluxes and legacy P when designing strategies to reduce P pollution. SABO ET AL.

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Section: Introductionmentioning

confidence: 99%

Phosphorus Inventory for the Conterminous United States (2002–2012)

et al. 2021

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“…Consequently, recent studies investigated the spatiotemporal variabilities of solute inputs and their impact on surface water quality (Böhlke et al, 2002; Chanat & Yang, 2018; Garnier et al, 2018; Kennedy et al, 2018; McCrackin et al, 2017; McInerney et al, 2018; Zimmer et al, 2019). In some cases, inverse modeling approaches for solute input estimation are suggested (Goyette et al, 2019; Luscz et al, 2017; Miller et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Depth of Solute Generation Is a Dominant Control on Concentration‐Discharge Relations

Botter¹,

Hartmann

et al. 2020

Water Resources Research

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Solutes in rivers often come from multiple sources, notably precipitation (above) and generation from the subsurface (below). The question of which source is more influential in shaping the dynamics of solute concentration cannot be easily addressed due to the general lack of input data. An analysis of solute concentrations and their dependence on discharge across 585 catchments in nine countries leads us to hypothesize that both the timing and the vertical distribution of the solute generation are important drivers of solute export dynamics at the catchment scale. We test this hypothesis running synthetic experiments with a tracer‐aided distributed hydrological model. The results reveal that the depth of solute generation is the most important control of the concentration‐discharge (C‐Q) relation for a number of solutes. Such relation shows that C‐Q patterns of solute export vary from dilution (Ca2+, Mg2+, K+, Na+, and Cl−) to weakly enriching (dissolved organic carbon). The timing of the input imposes a signature on temporal dynamics, most evident for nutrients, and adds uncertainty in the exponent of the C‐Q relation.

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“…Goyette et al. (2019) found that the number of dams in temperate basins was positively related to the export of N and attributed this relationship to legacy effects and saturation of the retention capacity of the reservoirs. Although this may seem contradictory to our results, it is possibly an interesting difference also linked to the association of water regulation with aridity.…”

Section: Discussionmentioning

confidence: 99%

“…Water regulation practices in arid regions promote N retention more than P retention, thereby increasing the N:P of the terrestrial fraction and decreasing the N:P of river exports, and contributing to narrowing the water‐soil gap in N:P ratios. Increased erosion and flashy precipitation in arid basins also contribute to lower the N:P ratio of freshwaters, because storms disproportionately favor the transport of P sorbed on to particles (Goyette et al., 2019; Green & Finlay, 2010). The N:P of river exports in arid and semiarid regions can decrease further with a reduction of inhabitant specific water resources: the population has only limited surface water resources to dispose of waste, which causes enrichment of P from urban sewage.…”

Section: Discussionmentioning

confidence: 99%

“…This is possibly because P retention is already very high and shows less variability, but also due to the fact that (1) in arid regions the presence of reservoirs is closely related to that of irrigation infrastructures, which largely favor N removal processes; and (2) anoxia is common in bottom waters of deep reservoirs, which also contributes to increase denitrification. Goyette et al (2019) found that the number of dams in temperate basins was positively related to the export of N and attributed this relationship to legacy effects and saturation of the retention capacity of the reservoirs. Although this may seem contradictory to our results, it is possibly an interesting difference also linked to the association of water regulation with aridity.…”

Section: Water Management Enhances Nutrient Retention In Arid Basinsmentioning

confidence: 99%

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The Mediterranean Region as a Paradigm of the Global Decoupling of N and P Between Soils and Freshwaters

Romero

Ludwig

Sadaoui

et al. 2021

Global Biogeochemical Cycles

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Socioeconomic development and agricultural expansion are accompanied not only by larger inputs of N and P but also by a serious alteration of the water cycle (Grill et al., 2019). This coupling between water and nutrient resources underscores the need to address food security and water security as interrelated challenges. Agriculture accounts for 69% of annual water withdrawals worldwide (FAO Aquastat). Some of the countries currently making major efforts to expand irrigation systems are in arid and semiarid regions of the world, which entails intensive groundwater abstraction and the construction of dams and reservoirs to secure the access to water resources. Reservoir storage is also the classic solution applied to contend with water scarcity in areas experiencing urban and industrial expansion (Gleick, 2003). How human water management may affect the stocks and fluxes of N and P is a question that has received little attention so far. Studies that deal with water and nutrients at once are usually performed at the small-scale, analyzing specific agricultural patches (e.g., Bartoli et al., 2012; Törnqvist et al., 2015), and focus on (1) increasing crop yields without compromising water resources; or (2) agricultural practices as a means of reducing nutrient loads and shortcutting water eutrophication. Furthermore, the vast majority of these studies concern wet temperate systems, which are those for which the most data exist, but very few provide data specific to arid and semiarid conditions. Arid and semi-arid regions constitute a significant fraction of the Earth's terrestrial ecosystems, and are expected to increase in upcoming years (IPCC 2014), so filling this data gap is of concern in light of future climate scenarios. The Mediterranean basin offers a unique test-bed to assess the coupling of N, P with water management for several reasons. First, because it comprises a gradient of climatological regimes (Figure 1) and different

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Differential influence of landscape features and climate on nitrogen and phosphorus transport throughout the watershed

Cited by 47 publications

References 80 publications

Phosphorus Inventory for the Conterminous United States (2002–2012)

Phosphorus Inventory for the Conterminous United States (2002–2012)

Depth of Solute Generation Is a Dominant Control on Concentration‐Discharge Relations

The Mediterranean Region as a Paradigm of the Global Decoupling of N and P Between Soils and Freshwaters

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