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Sedimentation in Bohai Bay, China and
Its Environmental Implications
Prof. Xueqiang Lu
College of Environmental Science and Engineering
Nankai University
从源头到海洋-波罗的海与渤海地区流域与近岸海域环境综合治理研讨会
Nov 8, 2018
Background
Coastal areas are generally well developed economically and the impact of human
activities on coastal environment is often intense.
World Night Light Map by NASA China
Background
Bohai Economic Ring
Yangtze River Delta Economic Ring
Pearl River Delta Economic Ring
Three Economic Rings in China
Coastal sediments are reliable
archives of environmental
processes and evolution in a
relatively stable sedimentary
environment.
Particulate matters from different
sources convey certain information
about the environmental in which
they originated.
Background
Sources of marine sediments
Background
Sedimentation rate, which allows to reconstruct environmental evolution processes and to
characterize the human impact on the coastal environment. The sedimentation rate is partly
controlled by the sediment supply, which depends on climate, transformation of river and its
catchment, as well as other processes occurring in the sea.
Factors Influence Factors Influence
Transformation of river and its catchment Climate
Reclamation in delta area +++ Flood (rainfall) +++
Deforestation +++ Temperature (erosion rate) +
Improvement of river banks in the downstream area ++ Wind +
Construction work to create new residential areas
(Urbanization)+ Factors in seas
Agriculture + Reclamation +++
Domestic effluent (Population) + Dredging +++
Industrial effluent (Industrialization) + Protection of shoreline --
Dam construction --- Current +/-
Protection of hill slopes and banks with concrete in the
upstream area-- Sea level rise (beach erosion) +
Methods
210Pb method
Constant flux of lead-210 model
m
m
m
m
t
A
dmA
A
fetS
)(
Mixing model
To target the sedimentation rate change in coastal seas over the last 100 years, 210Pb with
a half-life of 22.3 years is obviously the most suitable method. In addition, 137Cs dating is
on basis of its peak fallout in 1963, and suitable to date the sediment within the last 40-50
years. It has often been used as a tracer to provide supplementary information on
sedimentation rate to compare with the result derived from 210Pb method.
Sample collection and analysis
Locations of sampling
Sampling was conducted in Bohai
Bay in August 2011 at locations
determined bathymetrically with
water depth of 5 m, 10 m and 20 m
The radio activities for dried and
homogenized samples weighting of
23 g in calibrated geometries were
counted for 48 h to 72 h, using a
high-purity germanium detector
(GMX60P4, EG&G ORTEC) .
Profiles of excess 210Pb and 137Cs
60
50
40
30
20
10
00.00 0.02 0.04 0.06 0.08 0.10
BH1
Activity (Bq/g)M
assd
ep
th (
cm
)
40
35
30
25
20
15
10
5
00.00 0.02 0.04 0.06 0.08
BH2
Activity (Bq/g)
Massd
ep
th (
cm
)
45
40
35
30
25
20
15
10
5
00.00 0.03 0.06 0.09 0.12
Activity (Bq/g)
Massd
ep
th (
cm
)
BH340
35
30
25
20
15
10
5
00.00 0.03 0.06 0.09 0.12
BH4
Activity (Bq/g)
Massd
ep
th (
cm
)
40
35
30
25
20
15
10
5
00.00 0.03 0.06 0.09 0.12
BH5
Activity (Bq/g)
Massdepth
(cm
)
60
50
40
30
20
10
00.00 0.03 0.06 0.09 0.12
BH6
Activity (Bq/g)
Massdepth
(cm
)
40
35
30
25
20
15
10
5
00.00 0.02 0.04 0.06
BH7
Activity (Bq/g)
Massd
ep
th (
cm
)
30
25
20
15
10
5
00.00 0.02 0.04 0.06 0.08
Activity (Bq/g)
BH10
Massdepth
(cm
)
40
35
30
25
20
15
10
5
00.00 0.02 0.04 0.06 0.08
BH11
Activity (Bq/g)
Massd
ep
th (
cm
)
30
25
20
15
10
5
00.00 0.03 0.06 0.09 0.12
Activity (Bq/g)
Massd
ep
th (
cm
)
BH1240
35
30
25
20
15
10
5
00.00 0.03 0.06 0.09 0.12
Activity (Bq/g)
Massdepth
(cm
)
BH13
Profiles of
excess 210Pb
(solid square)
and 137Cs
(open square)
The profiles of excess 210Pb in reconstructed cores showed a non-linear and non-monotonic decrease with mass depth. The
activities of excess 210Pb were stable below the depth of 20 cm while it showed an increasing trend above that depth. Activities
of 137Cs were low, with no distinct peak.
Variations of the sedimentation rate
0.2 0.4 0.6 0.8 1.0
1860
1880
1900
1920
1940
1960
1980
2000
BH1
Sedimentation rate (g/(cm2y))
0.2 0.4 0.6 0.8 1.0
1880
1900
1920
1940
1960
1980
2000
BH2
BH1
Sedimentation rate (g/(cm2y))
0.2 0.4 0.6 0.8 1.0
1880
1900
1920
1940
1960
1980
2000
Sedimentation rate(g/(cm2y))
BH3
0.0 0.2 0.4 0.6 0.8 1.0
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
BH4
Sedimentation rate (g/(cm2y))
0.2 0.3 0.4 0.5 0.6
1880
1900
1920
1940
1960
1980
2000
BH5
Sedimentation rate (g/(cm2y))
0.2 0.4 0.6 0.8 1.0
1880
1900
1920
1940
1960
1980
2000
BH6
Sedimentation rate (g/(cm2y))
0.0 0.2 0.4 0.6 0.8 1.0
1800
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
BH7
Sedimentation rate (g/(cm2y))
0.0 0.2 0.4 0.6 0.8 1.0
1880
1900
1920
1940
1960
1980
2000
BH10
Sedimentation rate (g/(cm2y))
0.0 0.2 0.4 0.6 0.8
1860
1880
1900
1920
1940
1960
1980
2000
BH11
Sedimentation rate (g/(cm2y)) 0.0 0.2 0.4 0.6 0.8 1.0
1860
1880
1900
1920
1940
1960
1980
2000
BH12
Sedimentation rate (g/(cm2y))
0.2 0.3 0.4 0.5 0.6
1880
1900
1920
1940
1960
1980
2000
BH13
Sedimentation rate (g/(cm2y))
Sedimentation
rates derived
from 210Pb
Sedimentation rates ranged from 0.313±0.072 g/(cm2·y) to 0.493±0.129 g/(cm2·y), with a mean value of 0.378±0.204 g/(cm2·y).
Model verification
Comparison of mean sedimentation rate (g/(cm2·y)) derived from the 210Pb and 137Cs methods
in different cores
Core 210Pb method 137Cs method Relative Error
BH1 0.369±0.102 0.343±0.113 7.05%
BH3 0.464±0.123 0.389±0.096 16.16%
BH4 0.398±0.131 0.333±0.102 16.33%
BH5 0.371±0.115 0.341±0.111 8.09%
BH6 0.473±0.134 0.566±0.114 16.43%
BH7 0.385±0.203 0.302±0.099 21.56%
BH12 0.246±0.168 0.303±0.097 18.81%
BH13 0.301±0.054 0.314±0.104 4.14%
The relative error of mean sedimentation rates derived from the two methods was from
4.14% (core BH13) to 21.56% (core BH7). There was a distinct peak of 137Cs in core BH13 and
the relative error of mean sedimentation rates of both methods was the smallest, which
means that the 210Pb method was valid.
Spatial distribution of the sedimentation rates with time
In the northern area of
Bohai Bay, the
sedimentation rate was
relatively high from
1920 to 1980, while its
spatial distribution in
the rest of Bohai Bay
were large varied
greatly after 1980. This
indicates the impact of
human activities on
sedimentation rates
after 1980.
Temporal variation of the average sedimentation rate
Variation of sedimentation rate (box chart) and sediment flux
(solid square) in Bohai Bay in different years
1920 1940 1960 1980 2000
0.0
0.2
0.4
0.6
0.8
1.0
Sed
imen
tati
on
rate
(g/(
cm
2y
))
0
5
10
15
20
25
Sed
imen
tati
on
flu
x (
10
6 t
on
s)
The remarkable increase in sedimentation
rates after 1980, in a larger context, may be
related to the Chinese policy of economic
reform and opening-up in 1978.
1980 The sedimentation rates before 1980 were
relatively stable, ranging from 0.26±0.04
g/(cm2·y) in 1920 to 0.39±0.08 g/(cm2·y) in
1980. An accelerated increase in
sedimentation rates was found from
0.39±0.08 g/(cm2·y) in 1980 to 0.84±0.13
g/(cm2·y) in 2010.
The average sedimentation flux was
estimated at 0.38 million tons per decade
from 1920 to 1980. However, from 1980 to
2010, the sedimentation flux increased
dramatically, to a rate of 3.19 million tons
per decade.
Influencing factors
Main influencing factor before 1980: Riverine input
The river discharge significantly affected
the sedimentation rate due to the carried
large quantities of riverine sediments. It
can be discovered from the obvious
linear correlation between the collected
river discharge and the riverine
suspended particles discharges (R2=0.941,
n=44).
Correlation analysis on the river discharge and riverine
sediment discharges
0 2 4 6 8 10 12 14 16
0
200
400
600
800
1000
Riv
erin
e se
dim
ent
dis
char
ge
(10
3 t
on
s)
River discharge (109 m
3)
R2=0.941
n=44
Influencing factors
Main influencing factor before 1980: Riverine input
1950 1960 1970 1980 1990 20000
50
100
150
200
250
300
Ru
no
ff 1
08 m
3
In the 1950s, the average river
discharge was 1.44×1010 m3. There
was a turning point in 1980, from
which the river discharge reduced
rapidly to 1.0×109 m3. During the
21st century, the average river
discharge was significantly lower,
around 3.2×107 m3 per year.
Variation characteristics of river discharge
Influencing factors
Main influencing factor after 1980: Coastal reclamation
Coastal reclamation: backfill method
From 1984 to 2010, the area of coastal reclamationabout each five year was 53.53 km2, 100.04 km2 and485.95 km2, respectively. From 2010 to 2014, thereclamation area was 171.06 km2.
Change of reclamation areas along the
coastline of Bohai Bay in different periods
Influencing factors
0 10 20 30 40 50 60 70 80-35
-30
-25
-20
-15
-10
-5 marine sediment
river sediment
terrestrial soil
δ13C
C/N
C3 Land PlantsC4 Land Plants
Marine Algae
Lacustrine Algae
Comparing the results of this study with
the range of values of δ13C and C/N
ratios found in the literature for four
types of plants suggests that marine
algae deposition could be the main
source of the OM in Bohai Bay
sediments, while lacustrine algae may be
the main source of OM in the Bohai Bay
catchment riverine sediments.δ13C values vs atomic C/N ratios in the collected
marine, riverine, and terrestrial sediments (the four big
circles show the ranges of δ13C values and the atomic
C/N ratios in marine algae, lacustrine algae, C3 land
plants, and C4 land plants, respectively.) (Meyers, 1994)
Additional indirect influencing factor after 1980: Eutrophication
Sources of OM in sediments of Bohai Bay
Influencing factors
Additional indirect influencing factor after 1980: Eutrophication
1980 1985 1990 1995 2000 2005
0
1
2
3
4
5
Eu
tro
ph
icat
ion
in
dex
non-eutrophication
eutrophication
serious
eutrophication
Eutrophication could lead to higher
abundance of alga, whose growth
and death processes will add more
OM to the inventory.
Algae outbreaks could contribute
to the removal of more fine clay
particles, which eventually helps to
increase the sedimentation rate.
Eutrophication index of Bohai Bay
Influencing factors
1985 1990 1995 2000 2005 2010 2015
100
200
300
400
500
600
700
800
900
1000 Domestic sewage
Industrial wastewater
Total discharged volume
Waste
wate
r d
isch
arg
ed
vo
lum
e (
10
6 t
on
s)
1950 1960 1970 1980 1990 2000 2010
0
2
4
6
8
10
Ou
tpu
t (1
06 t
on
s)
Eggs
Meat
Vegetable
Oil-bearing Crops
Cotton
Grain
Influencing factor on Eutrophication
Wastewater discharge Chemical fertilizers
Environmental effects
The negative environmental effects from increase of sedimentation rates:
Excessive sedimentation will increase turbidity of sea water bodies and affect the light
transmittance. Ultimately, it will affect the primary productivity of the ocean and some
light sensitive marine organisms.
Excessive deposition will affect the habitat of marine organisms, especially for benthos.
Excessive sedimentation will transport those harmful substances into the sediments,
making coastal sediments become a potential risk source for marine ecosystems.
Positive or negative feedbacks?
40
35
30
25
20
15
10
5
00.2 0.4 0.6 0.8 1.0 1.2
Concentration (mg/kg)
Dep
th (
cm)
a Cd40
35
30
25
20
15
10
5
090 120 150 180 210 240
Concentration (mg/kg)
Dep
th (
cm)
b Cr40
35
30
25
20
15
10
5
010 20 30 40 50
Concentration (mg/kg)
Dep
th (
cm)
c Cu
40
35
30
25
20
15
10
5
010 15 20 25 30 35 40
Concentration (mg/kg)
Dep
th (
cm)
d Pb40
35
30
25
20
15
10
5
060 80 100 120 140 160
Concentration (mg/kg)
Dep
th (
cm)
e Zn40
36
32
28
24
20
16
12
8
4
00.0 0.2 0.4 0.6 0.8
Dep
th (c
m)
BH1
BH2f BH3
Sedimentation rate (g/a)
Influence of sedimentation rate on the metal contamination in
sediments (Open and solid marks represent metal concentrations before
and after adjustment, respectively.)
Through the adjustment, the
change of metal concentration in
sediment cores increased
obviously from bottom to
surface sediments. It indicated
that the increasing
sedimentation rate of Bohai Bay
in recent years diluted the metal
concentration in the sediment.
S1:大神堂S2:永定新河河口S3:海河河口S4:大沽排污河河口S5:独流减河河口
微塑料采样点位S1
S2S3
S4
S5
Microplastics in the coastal sediments in Bohai Bay
微塑料分离数据结果——20目筛网筛下物
大神堂 永定新河河口 海河河口大沽排污河河
口独流减河河口
形态 碎片，纤维 碎片 碎片、纤维 碎片、纤维 碎片、纤维
颜色 绿，白 白 绿、白 绿、白 白
数量8个/500 g
(dw)1个/500 g (dw)
104个/500 g
(dw)
40个/500 g
(dw)
3个/500 g
(dw)
类型聚丙烯PP、聚酯PET
聚丙烯PP
聚丙烯PP、聚乙烯PE、聚酯PET
聚乙烯PE、聚丙烯PP、聚酯PET
聚丙烯PP、聚酯PET
尺寸（mm）碎片：
（6.1~2）×（1.0~0.5）
0.5×0.1碎片：
（6.0~0.8）×（1.8~0.1）
碎片：（9.0~0.7）×（1.0~0.1）
碎片：（2.0~0.5）×（0.8~0.2）
微塑料分离数据结果——20目筛网筛上物
大神堂永定新河河
口海河河口
大沽排污河河口
独流减河河口
形态碎片，纤维,
薄膜碎片 碎片、薄膜 碎片、薄膜 ——
颜色 绿，白 黑蓝、绿、红、
白白、黑
——
数量6个/500 g
(dw)
2个/500 g
(dw)
21个/500 g
(dw)
40个/500 g
(dw)
0个/500 g
(dw)
类型聚丙烯PP、聚乙烯PE、聚酯PET
聚酯PET聚丙烯PP、聚乙烯PE
聚丙烯PP ——
尺寸（mm）
碎片：（20~2.5）×（1.0~0.5）
薄膜：4.1×0.3；0.7×0.7
6；4.5
碎片：（21~3.9）×（1.6~0.2）薄膜：5×1
碎片：（24~0.7）×（1.1~0.1）
薄膜：3.5×1.7
——
Supported Funds and achievements
The National Natural Science Fundation of China
Tianjin Research Program of Applied Science and Advanced Technology
EU-funded Environmental Sustainability Program
[1] Xueqiang Lu, Yan Zhang, Honglei Liu, Meinan Xing, Xiaolong Shao, Feng Zhao, Xiaojuan Li, Qiongqiong Liu, Dan Yu, Xuezhu Yuan, Min Yuan. Influence of
early diagenesis on the vertical distribution of metal forms in sediments of Bohai Bay, China [J]. Marine Pollution Bulletin, 2014, 88(1-2): 155-161.
[2]Yan Zhang, Xueqiang Lu, Hongle Liu i, Qiongqiong Liu, Dan Yu. Identifying the sources of organic matter in marine and riverine sediments of Bohai Bay and
its catchment using carbon and nitrogen stable isotopes [J]. Chinese Journal of Oceanology and Limnology, 2015, 33(1): 204-209.
[3]Yan Zhang, Xueqiang Lu, Xiaolong Shao, Honglei Liu, Meinan Xing, Feng Zhao, Xiaojuan Li, Min Yuan. Influence of sedimentation rate on the metal
contamination in sediments of Bohai Bay, China [J]. Bulletin of Environmental Contamination and Toxicology, 2015, 95(4): 507-512.
[4]Yan Zhang, Xueqiang Lu, Naili Wang, Meinan Xin, Shiwei Geng, Jing Jia, Qinghui Meng. Heavy metals in aquatic organisms of different trophic levels and
their potential human health risk in Bohai Bay, China [J] Environmental Science and Pollution Research, 2016, DOI 10.1007/s11356-016-6948-y
[5]Yan Zhang, Xueqiang Lu, Xiaolong Shao, Chen Chen, Xiaojuan Li, Feng Zhao, Gang Li, Eijij Matsumoto. Temporal variation of sedimentation rates and
potential factors influencing those rates over the last 100 years in Bohai Bay, China [J]. Science of the Total Environment, 2016, 572: 68-76.
