Competing and accelerating effects of anthropogenic nutrient inputs on climate-driven changes in ocean carbon and oxygen cycles


"Nutrient inputs from the atmosphere and rivers to the ocean are increased substantially by human activities. However, the effects of increased nutrient inputs are not included in the widely used CMIP5 Earth system models, which introduce bias into model simulations of ocean biogeochemistry. Here, using historical simulations by an Earth system model with perturbed atmospheric and riverine nutrient inputs, we show that the contribution of anthropogenic nutrient inputs to past global changes in ocean biogeochemistry is of similar magnitude to the effect of climate change. [...]". 


Source: Science Advances
Authors: Akitomo Yamamoto et al. 
DOI: 10.1126/sciadv.abl9207

Read the full article here.

Global certified-reference-material- or reference-material-scaled nutrient gridded dataset GND13


"A global nutrient gridded dataset that might be the basis for studies of more accurate spatial distributions of nutrients in the global ocean was created and named GND13. During 30 cruises, reference materials of nutrients in seawater or their equivalents were used at all stations, and high-precision measurements were made. The precision of the nutrient analyses was better than 0.2 %. Data were collected from the hydrographic cruises in the JASMTEC R/V Mirai cruises, JMA cruise, CARINA, PACIFICA, and WGHC datasets from which nutrient data were available. [...]"

Source: Earth System Science Data
Authors: Michio Aoyama
DOI: 10.5194/essd-12-487-2020

Read the full article here.

Limited oxygen production in the Mesoarchean ocean


"The Archean Eon was a time of predominantly anoxic Earth surface conditions, where anaerobic processes controlled bioessential element cycles. In contrast to “oxygen oases” well documented for the Neoarchean [2.8 to 2.5 billion years ago (Ga)], the magnitude, spatial extent, and underlying causes of possible Mesoarchean (3.2 to 2.8 Ga) surface-ocean oxygenation remain controversial. [...]"

Source: PNAS
Authors: Frantz Ossa Ossa et al.
DOI: 10.1073/pnas.1818762116

Read the full article here.

The influence of decadal oscillations on the oxygen and nutrient trends in the Pacific Ocean


"A strong oxygen deficient layer is located in the upper layer of the tropical Pacific Ocean and at deeper depths in the North Pacific. Processes related to climate change (upper ocean warming, reduced ventilation) are expected to change ocean oxygen and nutrient inventories. In most ocean basins, a decrease in oxygen (‘deoxygenation’) and an increase of nutrients has been observed in subsurface layers. Deoxygenation trends are not linear and there could be other influences on oxygen and nutrient trends and variability. Here oxygen and nutrient time series since 1950 in the Pacific Ocean were investigated at 50 to 300 m depth, as this layer provides critical pelagic habitat for biological communities. [...]"

Source: Biogeosciences
Authors: Lothar Stramma et al.
DOI: 10.5194/bg-2019-91

Read the full article here.


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