Evaluating hypoxia alleviation through induced downwelling

Koweek, David A.; García‐Sánchez, Clara; Brodrick, Philip G.; Gassett, Parker; Caldeira, Ken

doi:10.1016/j.scitotenv.2020.137334

Cited by 21 publications

(16 citation statements)

References 40 publications

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“…S1). The downward penetration of surface waters, nonetheless, seemed restricted to the ~ 10-m isobath and thus offset only a limited amount of the oxygen reduction caused by biochemical consumption (Koweek et al 2020). DO concentrations in the bottom layer were reduced to ~ 46 μmol kg -1 off the Maodaomen sub-estuary along the 20-m isobath and to < 94 μmol kg -1 to the southwest of Hong Kong (Fig.…”

Section: Reinstatement Of Hypoxia After the Typhoonmentioning

confidence: 99%

Destruction and reinstatement of coastal hypoxia in the South China Sea off the Pearl River Estuary

Zhao¹,

Uthaipan²,

Lu³

et al. 2020

Preprint

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Abstract. We examined the evolution of intermittent hypoxia off the Pearl River Estuary during three cruise legs conducted in July 2018: one during severe hypoxic conditions before the passage of a typhoon and two post-typhoon legs showing destruction of the hypoxia and its reinstatement. The lowest ever regional dissolved oxygen (DO) concentration of 3.5 μmol kg−1 (~ 0.1 mg L−1) was observed in bottom waters during Leg 1, with a ~ 660 km2 area experiencing hypoxic conditions (DO

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Section: Reinstatement Of Hypoxia After the Typhoonmentioning

confidence: 99%

Destruction and reinstatement of coastal hypoxia in the South China Sea off the Pearl River Estuary

Zhao¹,

Uthaipan²,

Lu³

et al. 2020

Preprint

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“…A rapid decrease of sediment phosphate fluxes when anoxic bottoms in eutrophic estuaries were oxygenated by engineered destratification and reaeration was reported by Harris et al (2015). Different methods to alleviate bottom layer hypoxia through induced downwelling on shallow stratified shelves have recently been described by Koweek et al (2020) and Xiao et al (2018).…”

Section: Sea-based Measures Stopping the Ips Might Restore The Balticmentioning

confidence: 99%

The Eutrophication of the Baltic Sea has been Boosted and Perpetuated by a Major Internal Phosphorus Source

Stigebrandt

Andersson

2020

Front. Mar. Sci.

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The phosphorus (P) concentration c1 in the surface layer of the Baltic proper in winter depends on the land-based P source LPS, and the ocean P source OPS, which are known. It also depends on the internal P source IPS from anoxic bottoms and the sum of internal and external P sinks TPsink, which are estimated in this paper. IPS is parameterized as fs·Aanox, where fs is the specific annual mass flux of P from anoxic sediments and Aanox is the area of anoxic bottoms, and TPsink is parameterized as c1·TRVF, where TRVF is the total removal volume flux. We use a time-dependent P budget model, and 47 years of observational data, and the method of least squares to determine the best estimates of the unknown parameters fs and TRVF. The result is TRVF = 3,000 km3 year−1 and fs = 1.22 tons P km−2 year−1. With these parameter values, the model gives a quite good description of the observed evolution of c1. The observed runaway evolution of c1, with increasing c1 since the 1980s although the land-based supply LPS has been halved, is well-described by the model. It is concluded that the internal P source IPS provides a positive feedback mechanism that has boosted and perpetuated the eutrophication of the Baltic proper and that IPS is the major driver of the Baltic Sea eutrophication since the late 1990s. It is suggested that measures to eliminate IPS should be included in the management strategy to reduce the eutrophication of the Baltic proper.

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“…Adjustments to these nutrient targets, namely the TMDL, may be necessary to overcome downward-moving targets for O 2 resulting from warming. Emerging technologies have also been proposed to find engineered solutions to low O 2 conditions (Harris et al 2015;Koweek et al 2020), but the efficacy of these approaches in larger systems remains unclear (Conley et al 2009).…”

Section: Conclusion and Future Recommendationsmentioning

confidence: 99%

Modeling Impacts of Nutrient Loading, Warming, and Boundary Exchanges on Hypoxia and Metabolism in a Shallow Estuarine Ecosystem

Testa

Basenback

Shen

et al. 2021

J American Water Resour Assoc

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We sought to investigate the impacts of nutrient loading, warming, and open‐water boundary exchanges on a shallow estuary through idealized numerical model experiments. We performed these simulations using a stand‐alone implementation of the Regional Ocean Modeling System‐Row‐Column AESOP biogeochemical model in the Chester River estuary, a tributary estuary within the Chesapeake Bay estuarine complex. We found that metabolic rates were elevated in the shallow tributary creeks of the estuary relative to open waters and that rates of gross primary production, respiration, and net ecosystem metabolism were a function of both water temperature and local phytoplankton biomass. Warming 0.75°C and 1.25°C led to reductions in dissolved oxygen concentrations throughout the estuary. Reductions (50%) in dissolved nitrogen and phosphorus loading did not substantially alter hypoxic volumes in this turbid, nutrient‐rich estuary, but warming increased hypoxic volumes by 20%–30%. Alterations of the open‐water boundary that represent improved oxygen concentrations in the adjacent Chesapeake Bay mainstem led to more substantial relief of hypoxia in model simulations than nutrient reductions (~50% reductions in hypoxia). These simulations reveal the complex interplay of watershed nutrient inputs and horizontal exchange in a small tributary estuary, including the finding that future warming and nutrient reduction effects on Chesapeake Bay hypoxia will be translated to some tributary estuaries like the Chester River.

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Evaluating hypoxia alleviation through induced downwelling

Cited by 21 publications

References 40 publications

Destruction and reinstatement of coastal hypoxia in the South China Sea off the Pearl River Estuary

Destruction and reinstatement of coastal hypoxia in the South China Sea off the Pearl River Estuary

The Eutrophication of the Baltic Sea has been Boosted and Perpetuated by a Major Internal Phosphorus Source

Modeling Impacts of Nutrient Loading, Warming, and Boundary Exchanges on Hypoxia and Metabolism in a Shallow Estuarine Ecosystem

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