Kaijun Sua, Jinzhou Dua,*, Mark Baskaranb and Jing Zhang Kaijun Sua, Jinzhou Dua,*, Mark Baskaranb and Jing Zhang

aState Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, P.R.China

bDepartment of Geology, Wayne State University, Detroit, Michigan, 48202-3622, USA

aState Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, P.R.China

bDepartment of Geology, Wayne State University, Detroit, Michigan, 48202-3622, USA

210Po and 210Pb disequilibrium of the PN

section in the East China Sea

210Po and 210Pb disequilibrium of the PN

section in the East China Sea

1

Chapter 1 Introduction

The time scale of processes in the estuary/coast/ocean can be

evaluated with different half-life time radionuclides;

Dissolved Ra/Rn isotopes, is one of powerful tools to study the

materials diffusion process (i.e. nutrient offshore diffusion and

nutrient discharge with submarine groundwater discharg,SGD )

Particle-active radionuclides (i.e. 210Po/210Pb, and 7Be) can be

as tracers in dynamics of suspended particulate matter

(SPM), POC and the concerned particle-active pollutions(POPs,

PAH)

Behaviors of natural radionuclides in marine environment

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Sources of 210Po and 210Pb in the coastal waters

Cycling of 210Po, 210Pb in coastal waters (modified from Lin and Chung, 1991)

3

210Pb sources: Atmospheric

precipitation; decay from 226Ra in

the water and sediment 210Po sources: decay from 210Pb The half-life and affinities with

particles are different between 210Po and 210Pb — 210Po and 210Pb

disequilibria to trace

oceanographic processes

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Euphotic layer

210Po/210Pb disequilibrium210Po/210Pb disequilibrium

5

For example:210Po/210Pb to assessing POC fluxes

234Th/238U disequilibrium234Th/238U disequilibrium

Euphotic layer

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

5

Why? PN section of the East China Sea

Complex of water mass structures 0.5 Gt terrestrial particulate

matter(Wang, 2008) and 2-5 Mt organic matter (Wu et al., 2007) from the Changjiang river to the ECS every year.

Mean water depth = 370 m Two major sources of nutrients

upwelling of the Kuroshio Current’s subsurface waters (Chen et al., 1996) and the Changjiang (Yangtze) River (due to its tremendous river runoff)

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

The atmospheric deposition fluxes of 210Po and 210Pb

0.142 Summer0.122 Autumn0.820 Winter0.640 Spring

0.007 Summer0.231 Autumn0.926 Winter0.094 Spring

• In winter, there is a high correlation between the activities and rainfall.

• In spring, the pair possibly have different scavenging mechanisms.

Correlation coefficients

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

The properties of Riverine input

The particulate species are dominate, the same trend with TSM.

The Ratio in dissolved phase: 1.32. Compared with the ratio of deposition(0.22),

there is another source of the excess 210Po, possibly from the organic

contaminate in the river water

Yangtze River

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

8

Cruise time: Oct, 2013 Sampling sites: A CTD-Rosette assembly with Niskin bottles Sampling volume: 20 L

19.90~25.34°C

32.08~34.76

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

T-S of PN section of the East China Sea

3.33~167 mg L-1

1.00~41.75 μmol C L-1

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

POC and TSM of PN section of the East China Sea

10

Dissolved 210Po (DPo) 、 210Pb (DPb) and their ratio distribution at PN section

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

11

Particulate 210Po (PPo) 、 210Pb (PPb) and their ratio distribution at PN section

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

12State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Total 210Po (TPo) 、 210Pb (TPb) and their ratio distribution at PN section

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The positive correlation between different phase of 210Po and 210Pb and POC concentration was found, In different phase,210Pb was more affinities with POC than 210Po.

Radioactivities vs POC in the PN section of ECS

14State Key Laboratory of Estuarine and Coastal Research, East China Normal University

(Kd) vs TSM in the concerned seas

15State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Distribution coefficients (Kd) vs TSM in the concerned seas

One-dimension Scavenging ModelOne-dimension Scavenging Model

Weiand Murray, 1994

Dissolved

Dissolved

Particulate

Particulate

Sinking with particlesSinking with particles

Scavenging rate JPo

Removing rate PPo

h

10State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Scavenging and remove of 210Po/210Pb in the PN section

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Assumption:Ignoring the atmospheric deposition of 210Po (10% of the 210Pb depositional fluxes) comparing with the in-situ production (Lambert et al., 1982; Kim et al., 1999)Steady state — Ignoring the physical process

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

POC fluxes in the PN section

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Using One-dimension Steady state Scavenging Model to estimate the fluxes of 210Po, the effect of physical process always can’t be ignored. If we consider the impact of the runoff caused by Changjiang River flushing into the seawater.

Using One-dimension Steady state Scavenging Model to estimate the fluxes of 210Po, the effect of physical process always can’t be ignored. If we consider the impact of the runoff caused by Changjiang River flushing into the seawater.

𝑽= 𝒘𝝏𝑨 𝑷𝒐𝟐𝟏𝟎𝝏𝒛

V=0that

POC fluxes would be increase

Advection process impacts on the Po export flux

Methods Refernces Export layer/m

Depth/m

POC export flux /mg C m-2 d-1

Cruise time

Sediment traps

Huang et al., 2007

65 1947 26.8 Aug 2006

234Th/238U disequilibrium

Huang et al., 2007

65 1947 33.6 Aug 2006

234Th/238U disequilibrium

Bi et al., 2013

50 870 90.4 May 2011

210Po/210Pb disequilibrium

Bi et al., 2013

40 150 72.0 Oct 2011

210Po/210Pb disequilibrium

This study 40 24.6 Oct 2013

19

POC export flux in the East China Sea

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

20

-10

0

10

20

30

40

Hung et al., 2010

Hung et al., 2010

Buesseler et al., 1998

Yu et al., 2012

Moran et al., 2000

Cai et al., 2008

This studyThe continental slope of ECS

The Gulf of Mexico

The northeastern Taiwan

The Arabian Sea

The Chukchi Sea

The Beaufort Sea

The Southern China Sea

PO

C e

xport

flux

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Third International Conference on Po and Radioactive Pb Isotopes(INCO-PoPb-2015) ， October11-14,2015 ， Kusadası,Turkey

POC export flux in the other Sea(s)

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Summary and future work The distribution of total 210Po/210Pb was opposite to that of POC along PN

section in Fall 。 Generally speaking ， the export flux of POC was higher at the nearshore than the open sea

At PN section, The average residence time of D210Po 、 P210Po and T210Po in the PN section of ECS in fall was 0.52, 0.32 and 0.85 a, respectively.

A simple steady state box model-based export fluxes POC and PON out of the upper waters were found to be 24.6 mg C m-2 d-1 and 26.7 mg N m-2 d-1, respectively, with a decreasing trend of POC export fluxes with increasing offshore distance.

If we consider the impact of the runoff caused by Changjiang River flushing into the seawater, the POC fluxes would be increase.

Futrue work ： Modeling…

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

State Key Laboratory of Estuarine and Coastal Research, East China Normal University

Any questions are welcome!

AcknowledgementsThis research was supported by the the Ministry of Science and Technology of China (No: 2011CB409801） .