Review of “Phytoplankton growth responses to Asian dust additions in the Northwest Pacific Ocean versus the Yellow Sea” by Chao Zhang et al.

Abstract. In this study, five on-board microcosm experiments were performed in the subtropical gyre, the Kuroshio Extension region of the northwest Pacific Ocean (NWPO), and the Yellow Sea (YS) in order to investigate phytoplankton growth following the addition of artificially modified mineral dust (AM dust) and various nutrients (nitrogen (N), phosphorus (P), iron (Fe), N + P, and N + P + Fe). The two experiments carried out with AM-dust addition in the subtropical gyre showed a maximum chlorophyll a (Chl a) concentration increase of 1.7- and 2.8-fold, while the cell abundance of large-sized phytoplankton ( >  5 µm) showed a 1.8- and 3.9-fold increase, respectively, relative to the controls. However, in the Kuroshio Extension region and the YS, the increases in maximum Chl a and cell abundance of large-sized phytoplankton following AM-dust addition were at most 1.3-fold and 1.7-fold larger than those in the controls, respectively. A net conversion efficiency index (NCEI) newly proposed in this study, size-fractionated Chl a, and the abundance of large-sized phytoplankton were analysed to determine which nutrients contribute to supporting phytoplankton growth. Our results demonstrate that a combination of nutrients, N–P or N + P + Fe, is responsible for phytoplankton growth in the subtropical gyre following AM-dust addition. Single nutrient addition, i.e., N in the Kuroshio Extension region and P or N in the YS, controls the phytoplankton growth following AM-dust addition. In the AM-dust-addition experiments, in which the increased N–P or P was identified to determine phytoplankton growth, the dissolved inorganic P from AM dust (8.6 nmol L−1) was much lower than the theoretically estimated minimum P demand (∼ 20 nmol L−1) for phytoplankton growth. These observations suggest that additional supply augments the bioavailable P stock in incubated seawater with AM-dust addition, most likely due to an enhanced solubility of P from AM dust or the remineralization of the dissolved organic P.

Download Full-text

Phytoplankton growth responses to Asian dust additions in the Northwest Pacific Ocean versus the Yellow Sea

10.5194/bg-2017-176 ◽

2017 ◽

Author(s):

Chao Zhang ◽

Huiwang Gao ◽

Xiaohong Yao ◽

Zongbo Shi ◽

Jinhui Shi ◽

...

Keyword(s):

Kuroshio Extension ◽

Phytoplankton Growth ◽

Subtropical Gyre ◽

The Yellow Sea ◽

Northwest Pacific ◽

Northwest Pacific Ocean ◽

Chl A ◽

The Northwest Pacific Ocean ◽

The Kuroshio ◽

Kuroshio Extension Region

Abstract. In this study, five on-board microcosm experiments were performed in the subtropical gyre, Kuroshio Extension region of the Northwest Pacific Ocean (NWPO) and the Yellow Sea (YS), in order to investigate phytoplankton growth following the addition of artificially modified mineral dust (AM-dust) and various nutrients (nitrogen – N, phosphorus – P, iron – Fe, N + P, and N + P + Fe). The two experiments carried out with AM-dust addition in the subtropical gyre showed a maximum chlorophyll a (Chl a) concentration increase of 1.7- and 2.8-fold, while the cell abundance of large-sized phytoplankton (> 5 μm) showed a 1.8- and 3.9-fold increase, respectively, relative to the controls. However, in the Kuroshio Extension region and the YS, the increases in maximum Chl a and cell abundance of large-sized phytoplankton following AM-dust addition were at most 1.3-fold and 1.7-fold larger than those in the controls, respectively. A net conversion efficiency index (NCEI) newly proposed in this study, size-fractionated Chl a, and the abundance of large-sized phytoplankton were analysed to determine which nutrients contribute to support phytoplankton growth. Our results demonstrate that a combination of nutrients, NP or NPFe as well as other micro-constituents, are responsible for phytoplankton growth in the subtropical gyre following AM-dust addition. Single nutrient addition, i.e., N in the Kuroshio Extension region and P/N in the YS, controls the phytoplankton growth following AM-dust addition. In the AM-dust-addition experiments, wherein the increased NP or P were identified to determine phytoplankton growth, the dissolved inorganic P from AM-dust (8.6 nmol L−1) was much lower than the theoretically estimated minimum P demand (~ 20 nmol L−1) for phytoplankton growth. These observations suggest that additional supply augments the bioavailable P stock in incubated seawater with AM-dust addition, most likely due to an enhanced solubility of P from AM-dust or re-mineralization of the dissolved organic P.

Download Full-text

Aerosol iron and aluminum solubility in the northwest Pacific Ocean: Results from the 2002 IOC cruise

Geochemistry Geophysics Geosystems ◽

10.1029/2005gc000977 ◽

2006 ◽

Vol 7 (4) ◽

pp. n/a-n/a ◽

Cited By ~ 129

Author(s):

Clifton S. Buck ◽

William M. Landing ◽

Joseph A. Resing ◽

Geoffrey T. Lebon

Keyword(s):

Pacific Ocean ◽

Northwest Pacific ◽

Northwest Pacific Ocean ◽

The Northwest Pacific Ocean ◽

Aluminum Solubility

Download Full-text

Analysis of Atmospheric and Ionospheric Variations Due to Impacts of Super Typhoon Mangkhut (1822) in the Northwest Pacific Ocean

Remote Sensing ◽

10.3390/rs13040661 ◽

2021 ◽

Vol 13 (4) ◽

pp. 661

Author(s):

Mohamed Freeshah ◽

Xiaohong Zhang ◽

Erman Şentürk ◽

Muhammad Arqim Adil ◽

B. G. Mousa ◽

...

Keyword(s):

Wind Speed ◽

Pacific Ocean ◽

Tropical Cyclone ◽

Sea Level ◽

Northwest Pacific ◽

Northwest Pacific Ocean ◽

Sea Level Pressure ◽

Level Pressure ◽

Super Typhoon ◽

The Northwest Pacific Ocean

The Northwest Pacific Ocean (NWP) is one of the most vulnerable regions that has been hit by typhoons. In September 2018, Mangkhut was the 22nd Tropical Cyclone (TC) over the NWP regions (so, the event was numbered as 1822). In this paper, we investigated the highest amplitude ionospheric variations, along with the atmospheric anomalies, such as the sea-level pressure, Mangkhut’s cloud system, and the meridional and zonal wind during the typhoon. Regional Ionosphere Maps (RIMs) were created through the Hong Kong Continuously Operating Reference Stations (HKCORS) and International GNSS Service (IGS) data around the area of Mangkhut typhoon. RIMs were utilized to analyze the ionospheric Total Electron Content (TEC) response over the maximum wind speed points (maximum spots) under the meticulous observations of the solar-terrestrial environment and geomagnetic storm indices. Ionospheric vertical TEC (VTEC) time sequences over the maximum spots are detected by three methods: interquartile range method (IQR), enhanced average difference (EAD), and range of ten days (RTD) during the super typhoon Mangkhut. The research findings indicated significant ionospheric variations over the maximum spots during this powerful tropical cyclone within a few hours before the extreme wind speed. Moreover, the ionosphere showed a positive response where the maximum VTEC amplitude variations coincided with the cyclone rainbands or typhoon edges rather than the center of the storm. The sea-level pressure tends to decrease around the typhoon periphery, and the highest ionospheric VTEC amplitude was observed when the low-pressure cell covers the largest area. The possible mechanism of the ionospheric response is based on strong convective cells that create the gravity waves over tropical cyclones. Moreover, the critical change state in the meridional wind happened on the same day of maximum ionospheric variations on the 256th day of the year (DOY 256). This comprehensive analysis suggests that the meridional winds and their resulting waves may contribute in one way or another to upper atmosphere-ionosphere coupling.

Download Full-text