Correlation of Asian dust with chlorophyll and primary productivity in North Pacific Ocean Huiwang Gao Tan Saichun Xiaohong Yao Jinhui Shi Ocean University of China SOLAS OSC, , 2012, Cle Elum, WA, USA

Main routes of dust transport (arrows) and locations of the world’s major deserts. The magnitudes of dust emission from different regions are given in Mt and indicated using bars and the depositions to the oceans are also given in Mt and indicated by thick arrows (Shao et al., Aeolian Research, 2011)

Kellogg et al., Trends in ecology & evolution 2006 Principal ranges of the two major global dust transport systems. The African dust system (red–orange) has a strong seasonal component The Asian dust system (yellow) exports dust primarily during the spring

Okin et al., GBC, 2011

Studies that are underlined denote a relationship between dust and the biota, those that are not underlined denote that no relationship was reported. The underlined studies that are also overlined indicate that they have in subsequent re-analysis to be found to have misattributed the causes of the biological response to dust supply, for example the modelling study of Ridgewell (16) attributed high chlorophyll in the vicinity of the Kerguelen Plateau to be due to dust from South Africa, this region is characterised by high internal wave activity and a marine iron supply (Blain et al., 2007). Boyd et al., Marine Chemistry, 2010

Distribution of dust-event frequency, f DE, derived from the meteorological records of the 5-yr period between 27 May 1998 and 26 May Four regions of frequent dust events, i.e., the Tarim Basin, the Gobi region, the Hexi Corridor and the Indian Subcontinent, are denoted with A, B, C and D, respectively. Shao and Dong, Global and Planetary Change, 2006

Dust storm in Jiuquan, Gansu 20kg per capita A dust rain in Beijing, 2006

Monthly Asian dust-event frequency (bars) and strong-wind (larger than 6.5 m s −1 ) frequency (solid line with full dots) averaged over the period of Jan 1993–Dec 2001 (Kurosaki and Mikami, 2003).

Park et al., Science of the Total Environment, 2010 The annual total dry deposition of dust is found to be in the dust source region, 7.8 in the Yellow Sea, 6.5 in the Korean peninsula and 2.1 in the East Sea. Over the Yellow Sea the wet deposition contributes to 59% of the annual total deposition of dust (19.0) and over the East Sea/Japan Sea it contributes to 80% of the annual total deposition (10.7).

Rainfall: 5-15mm/day in YS (1) A phytoplankton bloom in the Yellow Sea in 2007 following a dust storm accompanied by precipitation.

A bloom was observed in the southern Yellow Sea on April 4 ～ 5 in a cruise, just several days after the dust event

Blooms were observed on these stations R/V Beidou( 北斗号 )

Concentration, μg m -3 Deposition rate, cm s -1 Deposition Flux, mg m -2 DryWetTotal Particle1498± ± ± ±19796 Sol-Al1.22± ± ± ±16.2 Sol-Fe0.81± ± ± ±10.9 Sol-P0.20± ± ± ±2.6 TIN-N 3.78±1.19 (NO 3 - ) 10.95±8.34 (NH 4 + ) 0.43 (NO 3 - ) 0.21 (NH 4 + ) 6.96± ± ±198.0 Table 1. Estimated dry and wet deposition fluxes for Fe, P, and inorganic nitrogen (TIN-N) over the Yellow Sea (mg m 2 ) Shi et al., submitted to JGR

Satellite Chl.a concentration images (SeaWiFS and MODIS).

Date Deposition, μmol m -2 d -1 Primary Production mol C m -2 d -1 Assimilation, μmol m -2 d -1 Fraction of deposition/ assimilation Sol FeTIN-NSol PFeNP NP Table 2. Dust deposition and nutrients assimilation by the phytoplankton Upwelling fluxes of NO 3 - and PO 4 3- were also calculated to be 4250  mol m -2 d -1 and 240  mol m -2 d -1 which are higher than those in normal days.

Chemical components & Chl.a in the surface water in SYS Background levels Increment after dust and rain events (%) Al37.4 nmol/L75 nmol/L (200%) Fe nmol/L DIN  mol/L1.77  mol/L (264%-25%) DIP n mol/L10.3 nmol/L (15%-2%) Chl.a mg/m mg/m 3 (350%-800%) *Fe, DIN and DIP increments were estimated by the ratios with dissolved Al in aerosols

Null hypothesis Probability One extra lagTwo extra lagsThree extra lagsFour extra lags N ≠>PP ** 2.×10 -7*** *** P ≠>PP ** 2.×10 -7** ** Fe ≠>PP ** 2.×10 -7*** *** Table 3. Causality test for atmospheric deposition and primary production The denotation ***, ** and * means that the null hypothesis on non-Granger causality is rejected at the 1%, 5% and 10% significance level, respectively.

(2) Correlation of Asian dust with chlorophyll and primary productivity in YS from 1998 to 2008

Tan et al., JGR, 2011 The yearly variations of dust frequency (days per year), annual average Chl a (SeaWiFS, MODIS/AQUA ) concentration and OPP in the south Yellow Sea and East China Sea.

Tan et al., JGR, 2011 Annual variations of bloom frequency and average days with AI (TOMS) ≥ 2 in the coastal seas of China including Bohai sea, Yellow sea and East China sea. Granger causality test shows the significant relationship between them.

(3) Variability of correlation between Asian dust storms and Chla in the Pacific Map of the study sea areas in the Pacific Ocean. Tan et al., Submitted to GRL

Averaged occurrence frequency of dust storms (days per year)

The correlation between monthly chlorophyll a concentration(Sea WiFS Level-3) (mg m -3 ) in the six sea areas and monthly dust frequency (days per month) for the period from September 1997 to December The minimum contour is 0.2 with significance level of 0.05.

Zhang and Gao, AE, 2007 Movement routes of Asian-dust aerosols to the sea in 2000–2002.

Back trajectory ensemble of Asian dust for Pacific Ocean from 10 May to 7 May 2007 using HYSPLIT model for altitude 6500m. Su and Toon, Atmos. Chem. Phys, 2011

KNOT PAPA ALOHA Asian dust events have changed the nutrients structure ( ), enhanced the biomass( ) even initiated algae bloom( ) in north Pacific Ocean

Summary Asian dust events sometimes can initiate algae bloom in coastal seas (YS and ECS) by nutrients supply. The correlations between chlorophyll a concentration and occurrence frequency of dust storms show Asian dust from different sources have varied impacts on bio-activities from marginal seas to the Pacific Ocean. Further studies are critical to understand the reasons behind the correlations not only by limiting nutrient supply (based on Redfield ratio), and by considering the synergistic enhancement or inhibition of multi-chemicals from dust deposition, probably like the effects of Chinese herbs on body health.

Chinese herbs

Thanks for your attention Thanks for your attention

Tu et al., 2011, Proc. of SPIE

Estimates of atmospheric deposition of (a) N (NDep), (b) P (PDep), and (c) Fe (FeDep) to the global. Okin et al., GBC, 2011

Days of strong dust storm, dust storm and blowing dust in China from 2000 to Zhang et al., Particuology, 2010 Times series of TDI and GDI for the period of Wang et al., AE, 2008

Global transported dust storm The dust originated from Taklimakan Desert during May 8-9, 2007 transports one full circuit around the global in approximately 13 days. Mean speed of dust transportation is about 2000km/day (Uno et al., 2009)