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Redox reactions and weak buffering capacity lead to acidification in the Chesapeake Bay

Abstract.

"The combined effects of anthropogenic and biological CO2 inputs may lead to more rapid acidification in coastal waters compared to the open ocean. It is less clear, however, how redox reactions would contribute to acidification. Here we report estuarine acidification dynamics based on oxygen, hydrogen sulfide (H2S), pH, dissolved inorganic carbon and total alkalinity data from the Chesapeake Bay, where anthropogenic nutrient inputs have led to eutrophication, hypoxia and anoxia, and low pH. [...]"

Source: Nature Communications
Authors: Wei-Jun Cai
DOI: 10.1038/s41467-017-00417-7

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The influence of variable slope-water characteristics on dissolved oxygen levels in the northern California Current System

Abstract.

"Observations have suggested a trend of decreasing dissolved oxygen (DO) and increasing spiciness in summertime mid-depth slope waters and bottom shelf waters along the United States west coast over the past 50 years, but they have also demonstrated a large amount of interannual and decadal variability. Shelf bottom water and slope water properties can be influenced by both local and remote effects, including changes in circulation or changes in the characteristics of the source waters supplying the region. [...]"

Source: Oceans
Authors: Scott M. Durski et al.
DOI: 10.1002/2017JC013089

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Denitrifying community in coastal sediments performs aerobic and anaerobic respiration simultaneously

Abstract.

"Nitrogen (N) input to the coastal oceans has increased considerably because of anthropogenic activities, however, concurrent increases have not occurred in open oceans. It has been suggested that benthic denitrification in sandy coastal sediments is a sink for this N. Sandy sediments are dynamic permeable environments, where electron acceptor and donor concentrations fluctuate over short temporal and spatial scales. The response of denitrifiers to these fluctuations are largely unknown, although previous observations suggest they may denitrify under aerobic conditions. We examined the response of benthic denitrification to fluctuating oxygen concentrations, finding that denitrification not only occurred at high O2 concentrations but was stimulated by frequent switches between oxic and anoxic conditions. [...]"

Source: The ISME Journal
Authors: Hannah K Marchant et al.
DOI: 10.1038/ismej.2017.51

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