Biogeochemical and environmental drivers of coastal hypoxia

Caballero-Alfonso, Ángela M.; Carstensen, Jacob; Conley, Daniel J.

doi:10.1016/j.jmarsys.2014.04.008

Cited by 58 publications

(25 citation statements)

References 42 publications

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“…In line with this, monitoring data in other parts of the Archipelago Sea consistently demonstrate progressive deoxygenation in the area during 5 last two decades (Fig. 7;Suomela 2011;Caballero-Alfonso et al, 2015). Therefore, we ascribe the decrease in Mo content at 1990 AD to dilution by the concurrently enhanced sediment MAR (Fig.…”

Section: Progressive Intensification Of Hypoxia During the Modern Warsupporting

confidence: 78%

“…Instead, we postulate that this deoxygenation was forced by the following complex 5 interplay of warming climate and millennial-scale changes in the basin configuration: (1) increased source-to-sink ratio, combined with intensified lateral sediment transport especially during early winter, enhanced sediment focusing and the MAR of Corg (Sect. 6.2.2); (2) decreased bottom water volume due to the gradual shoaling of the basin resulted in increased vulnerability to hypoxia (Caballero-Alfonso et al, 2015); (3) strengthened summer thermocline caused by global warming and gradual isolation of the basin hampered replenishment of the bottom water oxygen reservoir ; (4) 10 continuous accumulation of organic-rich brackish-water muds in the basin at least since ~ 500 AD has resulted in progressive depletion of electron acceptors ("oxygen debt") at the sea floor (Pamatmat, 1971). Accordingly, although we can not completely exclude the possible contribution of anthropogenic forcing, the onset of recurring seasonal hypoxia at around 1900 AD can be largely attributed to the naturally increased vulnerability to deoxygenation that together with global warming irreversibly tipped the ecosystem over a threshold, inducing a regime shift commonly associated with coastal oxygen 15 deficiency (e.g.…”

Section: Progressive Intensification Of Hypoxia During the Modern Warmentioning

confidence: 99%

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A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

Jokinen¹,

Virtasalo²,

Jilbert³

et al. 2018

Preprint

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Abstract. The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment.Here 5 we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented, and besides gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. The 10 progressive deoxygenation since the beginning of 1900s was originally triggered by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the anthropogenic eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s through fueling primary productivity, while we find no evidence of anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal 15 water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality. 25Biogeosciences Discuss., https://doi

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Section: Progressive Intensification Of Hypoxia During the Modern Warsupporting

confidence: 78%

Section: Progressive Intensification Of Hypoxia During the Modern Warmentioning

confidence: 99%

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

Jokinen¹,

Virtasalo²,

Jilbert³

et al. 2018

Preprint

View full text Add to dashboard Cite

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“…Nutrient-driven hypoxia is a continuing problem in near-coastal waters around the world, from the South China Sea in Asia [1] to the Baltic Sea in Europe [2] and the Gulf of Mexico [3] in North America. Freshwater lakes also continue to be plagued by problems of eutrophication, with excess nutrient loading leading to reports of harmful cyanobacterial blooms in areas such as Lake Taihu in China and Lake Erie in North America [4,5].…”

Section: Introductionmentioning

confidence: 99%

Time lags in watershed-scale nutrient transport: an exploration of dominant controls

Meter

Basu

2017

Environ. Res. Lett.

123

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Unprecedented decreases in atmospheric nitrogen (N) deposition together with increases in agricultural N-use efficiency have led to decreases in net anthropogenic N inputs in many eastern US and Canadian watersheds as well as in Europe. Despite such decreases, N concentrations in streams and rivers continue to increase, and problems of coastal eutrophication remain acute. Such a mismatch between N inputs and outputs can arise due to legacy N accumulation and subsequent lag times between implementation of conservation measures and improvements in water quality. In the present study, we quantified such lag times by pairing long-term N input trajectories with stream nitrate concentration data for 16 nested subwatersheds in a 6800 km 2 , Southern Ontario watershed. Our results show significant nonlinearity between N inputs and outputs, with a strong hysteresis effect indicative of decadal-scale lag times. The mean annual lag time was found to be 24.5 years, with lags varying seasonally, likely due to differences in N-delivery pathways. Lag times were found to be negatively correlated with both tile drainage and watershed slope, with tile drainage being a dominant control in fall and watershed slope being significant during the spring snowmelt period. Quantification of such lags will be crucial to policy-makers as they struggle to set appropriate goals for water quality improvement in human-impacted watersheds.

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“…Historically, removal of pollutant P from wastewater has been emphasized since excess concentrations can yield extraordinary phytoplankton growth, which can lead to eutrophication and subsequent development of hypoxia and acidification of surface water (Cai et al2011;Rittmann et al2011;Mayer et al2013). Eutrophication is a major water quality problem (Smith et al2014), and is the cause of at least 400 coastal dead zones worldwide (Diaz and Rosenberg 2008;Caballero-Alfonso, Carstensen and Conley 2015). In municipal wastewater treatment, enhanced biological phosphorus removal is often employed to achieve effluent concentrations as low as ∼0.1 mg-P L −1 , which approaches the kinetic and thermodynamic limit (Jenkins, Ferguson and Menar 1971;Jenkins and Hermanowicz 1991;Cooper, Dee and Yang 1993;Blaney, Cinar and Sengupta 2007).…”

Section: Introductionmentioning

confidence: 99%

High-affinity phosphate-binding protein (PBP) for phosphorous recovery: proof of concept using recombinantEscherichia coli

Yang¹,

Ballent²,

Mayer³

2016

FEMS Microbiology Letters

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Phosphorus (P) is a critical, non-renewable nutrient; yet excess discharges can lead to eutrophication and deterioration of water quality. Thus, P removal from water must be coupled with P recovery to achieve sustainable P management. P-specific proteins provide a novel, promising approach to recover P from water. Bacterial phosphate-binding proteins (PBPs) are able to effectively remove phosphate, achieving extremely low levels in water (i.e. 0.015 mg-P L −1 ). A prerequisite of using PBP for P recovery, however, is not only removal, but also controlled P release, which has not yet been reported.Phosphate release using recombinant PBP-expressing Escherichia coli was explored in this study. Escherichia coli was genetically modified to overexpress PBP in the periplasmic space. The impacts of NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Letters, Vol. 363, No. 20 (October 2016). DOI. This article is © Oxford University Press and permission has been granted for this version to appear in e-Publications@Marquette. Oxford University Press does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Oxford University Press. FEMS Microbiology 2ionic strength, temperature and pH on phosphate release were assessed. PBP-expressed E. coli demonstrated consistently superior ability to adsorb more phosphate from liquid and release more phosphate under controlled conditions relative to negative controls (unexpressed PBP E. coli and E. coli K12). Lower pH (3.8), higher temperature (35ºC) and higher ionic strength (100 mM KCl) facilitated increased phosphate release, providing a maximum of 2.1% P recovery within 3 h. This study provides proof of concept of the feasibility of using PBP to recover P.

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Biogeochemical and environmental drivers of coastal hypoxia

Cited by 58 publications

References 42 publications

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

Time lags in watershed-scale nutrient transport: an exploration of dominant controls

High-affinity phosphate-binding protein (PBP) for phosphorous recovery: proof of concept using recombinantEscherichia coli

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Biogeochemical and environmental drivers of coastal hypoxia

Cited by 58 publications

References 42 publications

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20&lt;sup&gt;th&lt;/sup&gt; century

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20&lt;sup&gt;th&lt;/sup&gt; century

Time lags in watershed-scale nutrient transport: an exploration of dominant controls

High-affinity phosphate-binding protein (PBP) for phosphorous recovery: proof of concept using recombinantEscherichia coli

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A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century