Dust storms have important climatic and environmental effect. Particularly, dust containing nutrients (nitrogen, phosphorus, and iron, etc.) could exert a significant influence on the biogeochemical cycle in downwind sea regions, stimulate marine biological productivity, and reduce atmospheric CO2 concentrations (“iron hypothesis” proposed in late 1980s). Since “iron hypothesis”, scientists begun to pay attention to the impacts of atmospheric deposition on marine biogeochemical cycle. However, few studies have examined the direct link between natural dust events and marine biological productivity.
In recent years, a series studies of Dr. TAN Saichun and Prof. SHI Guangyu from the Institute of Atmospheric Physics (IAP), CAS and their co-authors from Ocean University of China and Chinese Academy of Meteorological Sciences found that significant correlations were observed between East Asian dust events and chlorophyll a concentration not only in the open ocean of North Pacific Ocean (Tan et al., 2013), but also in the Chinese marginal seas (Tan et al., 2011; 2012a; 2013). In addition to long-term statistics analysis, dust storm cases studies also found that phytoplankton growth in the Yellow Sea was related to dust deposition (Tan et al., 2011; 2012b; 2014), and peak chlorophyll a concentration in dust years was above 40% higher than that in non-dust years (Tan et al., 2012b). Those studies suggested the effects of dust fertilization on marine biological productivity.
Recently, the team further investigated the transport process of East Asian dust events and quantitatively estimated the contribution of dust deposition to phytoplankton growth (Tan et al., 2016; 2017). They found that the combination of satellite-observed column and vertical properties of aerosol were able to show the transport of dust storms from the source regions to the research seas (Chinese marginal seas and southern North Pacific) and reduce the uncertainty of the identification of dust affecting the seas. The contribution of dust deposition to marine biological productivity was estimated from model simulated dust deposition flux. Results showed that dust containing iron was the most important factor affecting phytoplankton growth and the deposition of iron via severe dust storms satisfied the increase in demand required for phytoplankton growth (115–291%), followed by nitrogen (it accounted for up to 1.7–4.0%), and phosphorus was the smallest one (it accounted for up to 0.2–0.5%).
Figure 1. (a) SeaWiFS true color image (http://visibleearth.nasa.gov/view.php?id=55607) showed dust plume over the Chinese marginal seas; Phytoplankton bloom in the southern Yellow Sea (b), the East China Sea (c), and the North Pacific Subtropical Gyre (d).
References:
1. Tan, S.-C., G.-Y. Shi, J.-H. Shi, H.-W. Gao, X. Yao (2011). Correlation of Asian dust with chlorophyll and primary productivity in the coastal seas of China during the period from 1998 to 2008, Journal of Geophysical Research-Biogeosciences, 116, G02029, doi: 10.1029/2010JG001456.
2. Tan, S.-C., and G.-Y. Shi (2012a), Dust Storms in China and Correlation to Chlorophyll a Concentration in the Yellow Sea during 1997–2007, Atmospheric and Oceanic Science Letters, 5 (2), 1-5.
3. Tan, S.-C., and G.-Y. Shi (2012b), Transport of a Severe Dust Storm in March 2007 and Impacts on Chlorophyll a Concentration in the Yellow Sea, Scientific Online Letters on the Atmosphere, 8, 85-89.
4. Tan, S.-C., X. Yao, H.-W. Gao, G.-Y. Shi, and X. Yue (2013), Variability in the Correlation between Asian Dust Storms and Chlorophyll a Concentration from the North to Equatorial Pacific, PLoS ONE, 8(2), e57656. doi: 10.1371/journal.pone.0057656.
5. Tan, S.-C., Wang, H. (2014), The transport and deposition of dust and its impact on phytoplankton growth in the Yellow Sea, Atmospheric Environment, 99, 491-499.
6. Tan, S., J. Li, H. Gao, H. Wang, H. Che, and B. Chen (2016), Satellite-Observed Transport of Dust to the East China Sea and the North Pacific Subtropical Gyre: Contribution of Dust to the Increase in Chlorophyll during Spring 2010, Atmosphere, 7(11), 152.
7. Tan, S.-C., J. Li, H. Che, B. Chen, and H. Wang (2017), Transport of East Asian dust storms to the marginal seas of China and the southern North Pacific in spring 2010, Atmospheric Environment, 148, 316-328.
Contact: Dr. TAN Saichun, sctan@mail.iap.ac.cn
