kaijun su a, jinzhou du a, *, mark baskaran b and jing zhang a state key laboratory of estuarine and...
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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
13
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
17
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
18
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)
21
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) .
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