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Proterozoic seawater sulfate scarcity and the evolution of ocean–atmosphere chemistry

Abstract.

"Oceanic sulfate concentrations are widely thought to have reached millimolar levels during the Proterozoic Eon, 2.5 to 0.54 billion years ago. Yet the magnitude of the increase in seawater sulfate concentrations over the course of the Eon remains largely unquantified. A rise in seawater sulfate concentrations has been inferred from the increased range of marine sulfide δ34S values following the Great Oxidation Event and was induced by two processes: enhanced oxidative weathering of sulfides on land, and the onset of marine sulfur redox cycling. [...]"

Source: Nature Geoscience
Authors: Mojtaba Fakhraee et al.
DOI: 10.1038/s41561-019-0351-5

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Discrepancy in the Identification of the Atlantic/Pacific Front in the Central Arctic Ocean: NO Versus Nutrient Relationships

Abstract.

"Fronts in the NO parameter, a semiconservative tracer combining nitrate and dissolved oxygen, and dynamic height were observed in the central East Siberian Sea that distinguished Atlantic and Pacific contributions to the upper halocline of the Amerasian Basin during the summer of 2015. [...]"

Source: Geophysical Research Letters
Authors: Matthew B. Alkire, Robert Rember, Igor Polyakov
DOI: 10.1029/2018GL081837

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Multi-faceted particle pumps drive carbon sequestration in the ocean

Abstract.

"The ocean’s ability to sequester carbon away from the atmosphere exerts an important control on global climate. The biological pump drives carbon storage in the deep ocean and is thought to function via gravitational settling of organic particles from surface waters. However, the settling flux alone is often insufficient to balance mesopelagic carbon budgets or to meet the demands of subsurface biota. [...]"

Source: Nature
Authors: Philip W. Boyd
DOI: 10.1038/s41586-019-1098-2

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Organic carbon recycling in Baltic Sea sediments – An integrated estimate on the system scale based on in situ measurements

Abstract.

"In situ measured benthic fluxes of dissolved inorganic carbon (DIC), a proxy for organic carbon (OC) oxidation or recycling rates, are used together with burial rates based on measured sediment accumulation rates (SAR) and vertical distribution of OC in the sediment solid phase to construct a benthic OC budget for the Baltic Sea system. [...]"

Source: Marine Chemistry
Authors: Madeleine M. Nilsson et al.
DOI: 10.1016/j.marchem.2018.11.004

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Hydroxylamine as a Potential Indicator of Nitrification in the Open Ocean

Abstract.

"Hydroxylamine (NH2OH), a short‐lived intermediate in the nitrogen cycle, is a potential precursor of nitrous oxide (N2O) in the ocean. However, measurements of NH2OH in the ocean are sparse. Here we present a data set of depth profiles of NH2OH from the equatorial Atlantic Ocean and the eastern tropical South Pacific and compare it to N2O, nitrate, and nitrite profiles under varying oxygen conditions. [...]"

Source: Geophysical Research Letters
Authors: Frederike Korth et al.
DOI: 10.1029/2018GL080466

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Sri Lanka's marine protection agency calls for tougher laws against ocean pollution

"COLOMBO, April 11 (Xinhua) -- Sri Lanka's Marine Environment Protection Authority on Thursday urged countries along the Bay of Bengal to draft stronger laws against polluting the oceans due to the formation of a dead zone in the center of the Bay of Bengal.

General Manager of the Marine Environment Protection Authority, Dr. P.B. Teney told Xinhua that authorities had discovered the formation of a dead zone in the Bay of Bengal which had spread across a 6000 square kilometer area and was 100 meters to 400 meters in depth. [...]"

Source: XinhuaNet

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Role of organic components in regulating denitrification in coastal water of Daya Bay, southern China

Abstract.

"Both dissolved and particulate organic materials have been proposed to be important factors in regulating the heterotrophic denitrification in various aquatic environments. However, specific pathways and mechanisms remain elusive. In this study, water column samples were collected from Daya Bay, southern China, to examine the relationships between potential denitrification and different organic components in the water column. Bulk dissolved organic carbon (DOC) was categorized into three major components including terrigenous fluorescent (tFDOC), autochthonous fluorescent (bFDOC) and non-fluorescent (nFDOC) fractions, while the bulk particulate organic carbon (POC) was divided into terrigenous (tPOC) and autochthonous (bPOC) based on an isotope mixing model [...]"

Source: Environmental Science: Processes & Impacts
Authors: Jian Zeng
DOI: 10.1039/C8EM00558C

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Yield stability analysis reveals sources of large-scale nitrogen loss from the US Midwest

Abstract.

"Loss of reactive nitrogen (N) from agricultural fields in the U.S. Midwest is a principal cause of the persistent hypoxic zone in the Gulf of Mexico. We used eight years of high resolution satellite imagery, field boundaries, crop data layers, and yield stability classes to estimate the proportion of N fertilizer removed in harvest (NUE) versus left as surplus N in 8 million corn (Zea mays) fields at subfield resolutions of 30 × 30 m (0.09 ha) across 30 million ha of 10 Midwest states. [...]"

Source: Scientific Reports
Authors: Bruno Basso et al.
DOI: 10.1038/s41598-019-42271-1

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Coastal Mooring Observing Networks and Their Data Products: Recommendations for the Next Decade

Abstract.

"Instrumented moorings (hereafter referred to as moorings), which are anchored buoys or an anchored configuration of instruments suspended in the water column, are highly valued for their ability to host a variety of interchangeable oceanographic and meteorological sensors. This flexibility makes them a useful technology for meeting end user and science-driven requirements. [...]"

Source: Frontiers in Marine Science
Authors: Kathleen Bailey et al.
DOI: 10.3389/fmars.2019.00180

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Small zooplankton rings the alarm for oxygen loss in big oceans

"Hypoxia, a low level of oxygen that limits the physiological functions of animals, is a topic that fascinates many biologists. As climate change progresses, the frequency of hypoxic episodes in aquatic environments is increasing, putting fish species under stress and even reducing populations in some cases. But it is not only fish that suffer the ill effects of hypoxia. [...]"

Source: Journal of Experimental Biology
Author: Yangfan Zhang
DOI: 10.1242/jeb.199141

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