Download An experimental study on major element release from the sediments

J. Ocean Univ. China (Oceanic and Coastal Sea Research)
DOI 10.1007/s11802-015-2772-0
ISSN 1672-5182, 2015 14 (3): 417-424
http://www.ouc.edu.cn/xbywb/
E-mail:[email protected]
An Experimental Study on Major Element Release from the
Sediments in the Changjiang (Yangtze River) Estuary
GUO Yanwei*, and YANG Shouye
State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, P. R. China
(Received September 30, 2014; revised January 20, 2015; accepted March 2, 2015)
© Ocean University of China, Science Press and Springer-Verlag Berlin Heidelberg 2015
Abstract With the enhanced warming and acidification of global ocean, whether and to what extent the naturally-weathered fluvial sediment into the sea can release elements and thus influence the geochemical process and ecosystem of global ocean remain to
be resolved. In this contribution, an experimental study was carried out to examine the release rates of major elements (Ca, K, Mg
and Al) from the surface sediments in the Changjiang (Yangtze River) Estuary under the pH values of 4.0, 6.0 and 7.0. The two studied sediments consist primarily of quartz, plagioclase, calcite and clay minerals, with the BET (Brunauer, Emmett and Teller) surface
areas of 61.7 m2 g−1 and 23.1 m2 g−1. Major elements of Ca, K, Mg and Al show different release rates under different solution pH
values. With the decreasing solution pH, the release rates of Ca and K increase obviously, while the release rates of Mg and Al increase with the initial solution pH varying from 6.0 to 7.0. The different release rates of these elements are closely related to the
original mineral composition of the sediments and the reaction kinetics. Based on the experimental observation, quartz and clay minerals that have low dissolution rates may dominate the major element release to the aqueous phase. This study reveals that the enhancing ocean acidification could cause considerable release of major elements from natural terrigenous sediments into the ambient
marine environment, which has to be considered carefully in the future study on global change.
Key words
Changjiang Estuary; major elements; release rate; pH value; sediment
1 Introduction
Riverine transport from land to sea is a major process
for the global cycling of elements that are delivered to the
sea in dissolved and particulate forms (Gislason et al.,
2006). The total flux of particulate material is at least an
order of magnitude greater than the dissolved component,
and thus, dominates the cycling of most elements in continental margin (Oelkers et al., 2011; Jeandel et al., 2011).
To what extent the particulate matter influences the
chemical evolution of seawater depends on its dissolution
rate after it reaches the ocean. Therefore, the interaction
of riverine particulate material with seawater has to be
considered carefully, and some research methods were
developed (Jones et al., 2012; Oelkers et al., 2012; Pearce
et al., 2013). Jones et al. (2012) mixed riverine bedload
material and estuarine sediments from western Iceland
with open ocean seawater to assess the dissolution of riverine particulate material in seawater. Gherbi et al. (2010)
operated closed-system batch reactors in laboratory to
calculate the dissolution rates of sediments collected from
the Oued Cherf Reservoir. In addition, the release of heavy
metals from various sediments has been examined by the
* Corresponding author. Tel: 0086-21-65982208
E-mail: [email protected]
batch experiments in laboratory (Cappuyns and Swennen,
2005; Chakraborty et al., 2012; Yacoub et al., 2014).
At present, the socio-economic development and enhanced human activities have caused increasing pressure
on marine environment, such as ocean acidification and
warming, which is generated by abundant CO2 emissions
through fossil fuel combustion (Doney, 2010). Ocean
acidification would affect biogeochemical and ecological
processes of the coastal and estuary areas, and further
influence the stability of marine sediment with sources
from land, causing the release of elements from the seafloor sediments to the ambient seawater. Thus, the cycling
of elements in coastal marine environment in response to
oceanic environmental change is very important for the
chemical evolution of global ocean (Jeandel et al., 2011);
however, the related research is scare thus far. Most of
previous studies focus on the dissolution of natural or
authigenic minerals under different pH values and temperatures (Köhler et al., 2003; Gislason and Oelkers,
2003; Harouiya et al., 2007; Chaïrat et al., 2007;
Parthasarathy et al., 2013; Ramos et al., 2014).
The Changjiang (Yangtze River) is the largest river in
China and one of the largest in the word in terms of its
huge water and sediment discharges, which plays a critical role in terrestrial material cycle and ecosystem health
in the East China Sea (Saito et al., 2001; Yang et al., 2003;
Wang et al., 2008; Zhai and Dai, 2009). Based on the
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GUO et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2015 14: 417-424
long-term hydrologic observation, the water and sediment
discharges of the Changjiang average at 8964×108 km3
yr−1 and 390×106 t yr−1 respectively, which makes Changjiang the largest terrigenous source contributing to the
ECS. However, the sediment flux of the Changjiang has
been rapidly decreasing since the impoundment of the
Three Gorges Reservoir in 2003, averaging at only about
155×106 t yr−1 over the last ten years (2003–2013) (Changjiang Water Resources Commission, http://www.cjw.com.
cn/).
In recent years, the Changjiang delivered huge amount
of nutrients into the estuarine and coastal areas, resulting
in the deterioration of marine environment and the development of eutrophication, red tide and hypoxia in the
East China Sea (Li et al., 2002; Chen and Chen, 2003;
Wang, 2006; Chen et al., 2007; Cai et al., 2011). Unfortunately, most previous studies put the emphasis on the
effects of ocean acidification, warming and hypoxia on
the ecosystem and biogeochemical cycle of the Changjiang Estuary and the East China Sea, while how the estuarine and shelf sediments that are originally weathered
from the land respond to the rapid changes of oceanic
environment has never been revealed. However, this may
significantly influence the material cycle and biogeochemical process in the East China Sea and the west Pacific.
In this study, an experimental study was carried out in
laboratory to investigate the release rates of major elements (Ca, K, Mg and Al) from the surface sediments of
the Changjiang Estuary in the acidic environment with
different solution pH values. This study will provide new
insight into the current understanding of ocean acidification affecting biogeochemical process and element cycling in the coastal sea.
2 Materials and Methods
Two surface sediment samples named A6-5 and F6
were respectively taken from the Changjiang Estuary in
March 2013 and March 2012 (Fig.1), and the top 2 cm
was taken from the box corer. The geographic coordinates
are 122˚37.71΄E and 30º50.77΄N for A6-5, and 122º45΄E
and 31º17.25΄N for F6. The sediment samples were stored
in the refrigerator on board and land, and then dried at
60℃ in laboratory.
Sediments grain size was analyzed by the laser size
analyzer (Coulter LS230) at the State Key Laboratory of
Marine Geology in Tongji University, after processing the
samples with 10% H2O2 and 1 mol L−1 HCl to remove
organic matter and carbonate, respectively. The analytic
error for grain size composition is ≤ ±1%. The BET surface areas of the sediments were analyzed by N2 adsorption-desorption at 77 K on a Quanta Chrome Autosorb-IqMP Analyzer at the State Key Laboratory of Pollution
Control and Resource Reuse at Tongji University. The
contents of major minerals in the sediments were measured in a Rigaku DMAX2500 X-ray diffractometer (XRD)
at the First Institute of Oceanography in Qingdao.
For geochemical analyses, the contents of major oxides
in the bulk samples were analyzed by inductively coupled
plasma-atomic emission spectroscopy (ICP-AES) and
trace elements by inductively coupled plasma-mass spectrometry (ICP-MS) in the State Key Laboratory of Marine
Geology at Tongji University. Sediment powder was first
ignited under 600℃ in a muffle furnace to remove organic matter, and then 30 mg was dissolved in 1 mL 1:1
HNO3 and 3 mL pure HF for 24 h, heated to dryness. Attacked again by 1 mL of 1:1 HNO3 and 3 mL pure HF for
7 days, heated to dryness, and further digested by 4 mL of
1:1 HNO3. This digestion procedure results in complete
dissolution of the particulate samples. Uncertainties determined by the replicate samples and geostandards GSD9 do not exceed ±5%.
Fig.1 Study area with the sampling locations.
The batch experiment on element release was performed in a closed system for nearly two months, with the
method modified from Köhler et al. (2003), Yadav et al.,
(2008) and Jones et al. (2012). Approximately 0.4 g of
powdered sample was placed into the polypropylene
batch reactor, together with 500 mL of simulated seawater
with different pH values (4.0, 6.0 and 7.0). Then, the reactors were sealed and placed at a shaker with rotating
speed of 150 rpm (revolutions per minute) under room
temperature of 25℃. This setting allows the solution
complete mixing while not disturbing the particulate-water interface. For elemental determination, 20 mL of supernatant was regularly taken from the reactors through
0.22 μm cellulose acetate membrane filters. This sample
was divided into two sub-samples: one for pH analysis
and the other for elemental concentration measurement
using ICP-AES and ICP-MS.
In order to get the actual release rates of major elements from the sediments, avoiding the possible influence
from other elements of real water, the simulated seawater
was prepared by dissolving ultrapure NaCl to Milli-Q
water to get the solution containing 3.5% of NaCl, which
corresponds to the average salinity of normal seawater.
The pH of simulated seawater was controlled by 0.1 mol
L−1 HCl or 0.1 mol L−1 NaOH solutions. The pH of simu-
GUO et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2015 14: 417-424
lated seawater was allowed to vary during the experiment
due to the chemical reaction process between sediments
and simulated seawater (Pearce et al., 2013). The pH of
the supernatant was measured immediately after the sampling by using a standard glass electrode previously calibrated against the 4.01, 6.86 and 9.18 pH buffers.
419
samples of A6-5 and F6 calculated using the multi-point
BET method, are 61.74 m2 g−1 and 23.06 m2 g−1, respectively. These two samples are dominated by silty clay,
with the mean grain sizes of 11.9 μm and 11.7 μm. The
contents of SiO2 in A6-5 and F6 samples are about 55.2%
and 59.5% respectively, which corresponds well with the
dominance of quartz in the samples, accounting for
34.1% and 41.7% respectively. The contents of Al2O3 in
the samples are around 14.0%. The other major minerals
include feldspar (about 16.5%), calcite (about 5.0%) and
dolomite (about 2.9%), while illite dominates the clay
minerals in the sediments, averaging at 26.1%.
3 Results
The grain size, bulk compositions of elements and
minerals as well as BET surface areas of the samples are
listed in the Table 1 and Table 2. The surface areas of the
Table 1 BET surface areas, bulk compositions and grain size compositions of the investigated samples
Samples
Surface area Md Mz
Clay Silt Sand SiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O TiO2 K2O P2O5
S. D.
(μm) (μm)
(%) (%) (%) (%) (%) (%) (%) (%)
(m2 g−1)
(%) (%) (%) (%) (%)
A6-5
61.7
8.5 11.9 11.2 23.6 76.6 0.02 55.2 14.9 5.94
F6
23.1
8.6 11.7 13.4 22.6 76.5 0.9 59.5 13.7 5.43
Notes: Md, median grain size; Mz, mean grain size; S.D., standard deviation.
0.10
0.09
2.76 4.01 1.35 0.77 2.80 0.11
2.55 2.83 1.92 0.68 2.75 0.68
Table 2 Contents of major minerals in the A6-5 and F6 samples (%)
Samples
Quartz
Anorthite
K-feldspar
Calcite
Dolomite
Illite
Chlorite
Kaolinite
A6-5
F6
34.1
41.7
11.1
12.2
4.0
5.3
7.8
2.1
3.0
2.7
25.9
26.4
11.5
8.1
2.6
1.4
In this study, the pH values and major elemental concentrations in the supernatant were measured with the
reaction time for the calculation of the release rates of
major elements. The flux of each element released during
the experiment was determined as follows (Gherbi et al.,
2010):
M i  ci ,rVr   ci , nVn ,
(1)
n
where Mi stands for the mass of the ith element in the
supernatant phase; ci,r corresponds to the concentration of
this element in the supernatant present in the reactor; ci,n
represents the concentration in the nth supernatant sample,
and Vr and Vn denote the mass of supernatant present in
the reactor and taken as the nth sample.
The release fluxes of Ca, K, Mg and Al from A6-5 and
F6 samples under the solution pH of 4.0 change substantially with the onset of the experiments (Fig.2), showing a
rapid increase while the sediments reacting with the solution. For Ca and Mg, both elements are released from the
bulk samples continuously with time and then reach the
equilibrium after 400–600 h of the experiment. In comparison, K in the samples is released fast in the first 200 h,
reaching the highest value of 4.5 mg, and then the release
flux decreases and the equilibrium occurs after about 300
h, with the mass of around 1.5 mg. Element Al, however,
shows some different trends with time, overall increasing
until the experiment time of 1400 h. The release fluxes of
Ca and Mg show obvious difference between A6-5 and
F6 samples. The Ca release flux in A6-5 is less than that
in F6 at the first 300 h of the experiment. However, as the
reaction continues, A6-5 releases more Ca than F6, with
the equilibrium flux of around 7.0 mg in A6-5 and about
6.0 mg in F6. The release flux of Al in F6 is overall
higher than that in A6-5 sample throughout the experi-
ment.
This study also reveals that the solution pH in both
samples changes with the reaction time, showing the increasing at first and then a decreasing trend (Fig.3). For
instance, within the first 100 h of the experiment, the solution pH in A6-5 increases from initial solution pH 7.0 to
8.1, then decreases to 7.7 and finally reaches about 8.0.
Pearce et al. (2013) found the similar change in solution
pH while studying the reaction of basaltic samples with
seawater.
4 Discussion
4.1 pH Effect on the Release Rates of Major Elements
In order to evaluate the pH effect on the release rates of
major elements of interest, we calculate the percentages
of these four major elements released from the bulk samples relative to their bulk concentrations in F6 sample
(Fig.4). Obviously, these four elements display different
release percentages with the changes in solution pH.
Overall, Ca has the highest release percentages (>50%)
under various solution pH values than the other elements,
while Al has the lowest release percentages (<1%). In
addition, with the decrease of solution pH, the release
percentages for specific elements (Ca, K, Mg) increase,
especially for the solution pH value of 4.0, which implies
that under more acidic environment, more major elements
such as Ca, K and Mg are released more from the sediment.
The alkali earth metals Ca and Mg show overall increasing release percentages with time under different
solution pH values, and the release percentages are close
under the solution pH of 6.0 and 7.0. This suggests that the
solution pH near neutral condition has weak effect on Ca
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Fig.2 The release flux of major elements as a function of elapsed time with the initial solution pH of 4.0. For the
calculation, please refer to the Eq. (1) in the text.
Fig.3 Changes in solution pH during the experiment. The
numbers in brackets indicate initial pH values.
and Mg release. Based on the XRD results, we infer that
Ca and Mg in the studied sediments primarily reside in
calcite and dolomite. Considering the semi-quantitatively
estimation of major mineral contents in the sediments by
the XRD method, this study cannot make a stoichiometric
calculation on how many calcite and dolomite were dissolved during the batch experiment and how they contributed to the released Ca and Mg in the supernatant.
Nevertheless, this study reveals that these carbonate minerals are poorly attacked in the neutral solution compared
to the case of pH 4.0. Silicate minerals such as anorthite
in the sediments can also make some contribution to Ca
and Mg release, although it is difficult to quantitatively
calculate their influence. The more detailed characterization of residual sediments after the dissolution experiment
may be necessary to reveal the possible roles of carbonate
and silicate minerals in Ca and Mg release.
Both Ca and Mg are essential elements required for
marine organisms, and the continuous input of riverine
particulate material is fundamental to maintaining the
vitality of near coastal ecosystems (Bruland et al., 1991;
Jeandel et al., 2011). Therefore, any subtle environmental
change may alter the Ca and Mg availability in coastal
waters, which probably results in a significant impact on
marine ecosystem and seawater chemical evolution.
It is noteworthy that under the solution pH of 4.0, K is
released rapidly in the first 200 h and then stays at
40%–50% till 300 h. After about 300 h, the release percentage rapidly decreases to about 20%, and then reaches
equilibrium of adsorption and dissolution. Under the solution pH of 6.0 and 7.0, the K release percentages are
almost the same, showing very low values (<6.5%) and
weak increasing trends. This probably indicates that under acidic condition, some K-bearing minerals, e.g., illite,
kaolinite and K-feldspar in this study, may dissolve during the first stage of the experiments, while under neutral
condition, they are relatively resistant to alteration in marine environment. The large change in K release percentage with time under the solution pH of 4.0 is probably
caused by the subsequent incorporation of released K into
GUO et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2015 14: 417-424
the existing clay minerals or a newly-precipitated secondary phase. Jones et al. (2012) also found that when riverine particulate material weathered from basalt interacts
with seawater, the K concentration in the seawater also
decreases obviously after the initial increase. Further experiments on mineral compositions in the residual sediment samples after the dissolution will be necessary to
testify this speculation.
In comparison, Al shows obviously different variations
of release percentages with changing solution pH values,
yielding the overall highest release percentage in the solution pH of 7.0 and the lowest in the solution with pH
4.0 (Fig.4). Reitzel et al. (2013) found that in the solution
pH range of 7.5 to 9.5, while the uppermost Al-treated
sediment layer in a lake was resuspended, a significant
421
proportion of Al can be dissolved and the dissolution rate
increases with increasing pH. Some studies suggest that
the presence of aqueous Al3+ can decelerate the dissolution of aluminosilicates because of Al-inhibition, decreased chemical affinity, or both (Gautier et al., 1994;
Oelker et al., 1994; Chen and Brantley, 1997). For example, Chen and Brantley (1997) suggested that the decrease
in dissolution rate of albite in the presence of dissolved
aluminum may be attributed to increasing adsorption of
Al3+, which further inhibits the albite dissolution. Therefore, the mechanism for Al release from the sediments
under variable solution pH values seems to be complicated, involving the dissolution of aluminosilicates minerals in the sediment and the Al inhibition of other aluminosilicates.
Fig.4 The effect of solution pH on the release of Ca, Mg, K and Al from F6 sample.
4.2 Dissolution Rates of Major Elements Under
Different Solution pH
The release rates (ri) of elements can be estimated by
the following equation (Gherbi et al., 2010):
ri 
1
SBET
M i
,
t
(2)
where t denotes time, and SBET is the surface area of the
sediments present in the reactor; SBET can be calculated by
multiplying the mass of powder in the reactor by the
powder’s initial specific BET surface area. The slope of
the regression curve of Mi versus time t, i.e., ∂Mi/∂t has
been used to calculate element release rates based on Eq.
(2). In this study, the linear regression of element release
flux versus reaction time was obtained using the software
of Origin pro 8.0. The coefficients R2 of the linear regression for the element under different pH values range
widely from 0.30 to 0.95, and p ranging between 0.005
and 0.225. This regression method has been accepted and
used extensively in calculating pure mineral and sediment
dissolution rates (Köhler et al., 2003; Yadav et al., 2008;
Gherbi et al., 2010).
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GUO et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2015 14: 417-424
The logarithm values of release rates of Ca, K, Mg and
Al show that with the increasing of solution pH value, the
release rates of Ca and K decrease rapidly (Fig.5). This
may be related to the dissolution kinetics of different
minerals in the sediment. Under more acidic condition,
minerals such as calcite, dolomite and even some silicate
minerals in the sediments are more easily to be dissolved,
causing more Ca and K to be released to the solution. As
for Mg and Al, the pH effects on their release rates are not
obvious. The reason may be that elemental release rates
obtained in this research are normalized to the surface
area of the sediments, while the surface areas are dominated by those of clay minerals rather than by other minerals that contain Mg and Al (Sverdrup and Warfvinge,
1993). In addition, mineral dissolution rates depend
strongly on saturation state and solution composition.
Furthermore, the calculation of release rate by Eq. (2) has
been widely used for the dissolution experiments of minerals and lake sediments (Oelkers and Poitrasson, 2002;
Köhler et al., 2003; Gherbi et al., 2010), which is based
on the assumption that the element release flux has the
linear relationship with reaction time. However, the complicated mineral composition of the studied estuarine
sediments may cause the difference in the release fluxes
between different elements. Besides, under the pH range
of 4.0, 6.0 and 7.0, F6 has always higher element release
rates than A6-5 sample (Fig.5), which can be explained
by different clay mineral contents and surface areas between two studied samples. According to Eq. (2), the
higher surface area causes slower release rates, and thus
we suggest that clay mineral content and assemblage and
surface area of mineral grain are important factors influencing element release rate.
The comparison between element release rates generated in this study with dissolution rates of individual
minerals can provide insight into the water-sediment interaction. The logarithms of dissolution rate are higher
than −6 mol cm−2 s−1 for halite (Alkattan et al., 1997),
about −9.8 mol cm−2 s−1 for calcite (Cubillas et al., 2005),
and about −17.7 mol cm−2 s−1 for quartz (Brady and
Walther, 1990). For those of clay minerals, montmorillonite has the logarithm of dissolution rate of about −18.2
mol cm−2 s−1 (Rozalen et al., 2008) with that for kaolinite
being about −18.2 mol cm−2 s−1 (Huertas et al., 1999). The
measured logarithms of dissolution rates of the four elements in this research are in the range of −14.5 to −18.2
mol cm−2 s−1, which is close to that for the slowly-dissolving minerals including quartz and clay minerals, suggesting that these minerals may dominate the chemical
evolution of the aqueous phase during the experiment.
The dissolution rates of lake sediments calculated by
Gherbi et al. (2010) are close to those of quartz and caly
minerals, also suggesting that these minerals may control
the dissolution process of siliciclastic sediments.
Fig.5 Logarithm of element dissolution rates as a function of pH. For the detailed calculations, please refer to the Eq. (2)
in the text.
5 Conclusions
A batch experiment was designed in this study for the
investigation of major element release from the Changjiang estuarine sediments in the simulated seawater with
different acidic conditions. The studied sediments are
siltdominant and consist of quartz, plagioclase, calcite,
dolomite, illite and chlorite. The experimental results
suggest that the major elements of Ca, K, Mg and Al are
all released from the sediments under the solution pH of
4.0, 6.0 and 7.0, albeit with variable releasing rates and
fluxes. Under more acidic condition (pH 4.0), more Ca,
Mg and K are released from the sediments, while the
neutral solution (pH 6.0 and 7.0) causes weak release. Al,
however, shows somewhat increasing release under neutral condition with pH 7.0.
With the long-term reaction of the naturally-weathered
riverine sediments with saline water under different pH
values, Ca, K, Mg and Al exhibit variable release fluxes
and rates, which is not only determined by the solution
pH, but also tightly related to reaction kinetics and the
mineral characters (assemblage, surface area and grain
size, etc.) in the sediments. Overall, quartz and clay minerals that have low dissolution rates may dominate the
major element release to the aqueous phase with the ex-
GUO et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2015 14: 417-424
perimental time extending longer. This study reveals that
with the enhanced simulated seawater acidification, the
naturally-weathered terrigenous sediment may undergo
further dissolution, causing the release of major elements
(Ca, Mg, K and Al) into sea water. Our study may provide
new insight on the elemental cycle in a changing ocean.
Acknowledgements
This work was supported by research funds awarded by
the National Natural Science Foundation of China (Grant
Nos. 41225020 and 41376049), Continental Shelf Drilling
Program (Grant No. GZH201100202), and China Geologic
Survey (Grant No. GZH201100203).
References
Alkattan, M., Oelkers, E. H., Dandurand, J. L., and Schott, J.,
1997. Experimental studies of halite dissolution kinetics, 1
the effect of saturation state and the presence of trace metals.
Chemical Geology, 137: 201-219.
Brady, P. V., and Walther, J. V., 1990. Kinetics of quartz dissolution at low temperatures. Chemical Geology, 82: 253-264.
Bruland, K. W., Donat, J. R., and Hutchins, D. A., 1991. Interactive influences of bioactive trace metals on biological production in oceanic water. Limnology and Oceanography, 36:
1555-1577.
Cai, W., Hu, X., Huang, W. J., Murrell, M. C., Lehrter, J. C.,
Lohrenz, S. E., Chou, W. C., Zhai, W., Hollibaugh, J. T.,
Wang, Y., Zhao, P., Guo, X., Gundersen, K., Dai, M., and
Gong, G. C., 2011. Acidification of subsurface coastal waters
enhanced by eutrophication. Nature Geoscience, 4: 766-770.
Cappuyns, V., and Swennen, R., 2005. Kinetics of element release during combined oxidation and pHstat leaching of anoxic
river sediments. Applied Geochemistry, 20: 1169-1179.
Chaïrat, C., Schott, J., Oelkers, E. H., Lartigue, J. E., and
Harouiya, N., 2007. Kinetics and mechanism of natural
fluorapatite dissolution at 25℃ and pH from 3 to 12. Geochimica et Cosmochimica Acta, 71: 5901-5912.
Chakraborty, P., Babu, P. V. R., and Sarma, V. V., 2012. A study
of lead and cadmium speciation in some estuarine and coastal
sediments. Chemical Geology, 294-295: 217-225.
Chen, C. C., Gong, G. C., and Shiah, F. K., 2007. Hypoxia in the
East China Sea: One of the largest coastal low-oxygen areas
in the word. Marine Environmental Research, 64: 399-408.
Chen, J. Y., and Chen, S. L., 2003. Ecological environmental
changes in the Changjiang estuary and suggestions for countermeasure. Water Resources Hydropower Engineering, 34:
19-25 (in Chinese).
Chen, Y., and Brantley, S. L., 1997. Temperature- and pH-dependence of albite dissolution rate at acid pH. Chemical Geology, 135: 275-292.
Cubillas, P., Köhler, S., Prieto, M., Chaïrat, C., and Oelkers, E.
H., 2005. Experimental determination of the dissolution rates
of calcite, aragonite, and bivalves. Chemical Geology, 216:
59-77.
Doney, S. C., 2010. The growing human footprint on coastal and
open-ocean biogeochemistry. Science, 328: 1525-1516.
Gautier, J. M., Oelkers, E. H., and Schott, J., 1994. Experimental study of K-feldspar dissolution rates as a function of
chemical affinity at 150℃ and pH 9. Geochimica et Cosmochimica Acta, 58: 4549-4560.
423
Gherbi, C., Bouabse, L., and Oelkers, E. H., 2010. An experimental study of lake water-sediment interaction rates. Comptes
Rendus Geoscience, 342: 126-135.
Gislason, S. R., and Oelkers, E. H., 2003. Mechanism, rates, and
consequences of basaltic glass dissolution: II. An experimental study of the dissolution rates of basaltic glass as a function
of pH and temperature. Geochimica et Cosmochimica Acta,
67: 3817-3832.
Gislason, S., Oelkers, E. H., and Snorrason, Á., 2006. Role of
river suspended material in the global carbon cycle. Geology,
34: 49-52.
Harouiya, N., Chaïrat, C., Köhler, S., Gout, R., and Oelkers, E.
H., 2007. The dissolution kinetics and apparent solubility of
natural apatite in closed reactors at temperatures from 5 to
50℃ and pH from 1 to 6. Chemical Geology, 244: 554-568.
Huertas, F. J., Chou, L., and Wollast, R., 1999. Mechanism of
kaolinite dissolution at room temperature and pressure. Part II:
Kinetic study. Geochimica et Cosmochimica Acta, 63: 32613275.
Jeandel, C., Peucker-Ehrenbrink, B., Jones, M. T., Pearce, C. R.,
Oleers, E. H., Godderis, Y., Lacan, F., Aumont, O., and Arsouze, T., 2011. Ocean margins: The missing term for oceanic
element budgets? EOS, Transactions American Geophysical
Union, 92: 217-224.
Jones, M. T., Pearce, C. R., Jeandel, C., Gislason, S. R., Eiriksdottir, E. S., Mavromatis, V., and Oelkers, E. H., 2012. Riverine particulate material dissolution as a significant flux of
strontium to the oceans. Earth and Planetary Science Letters,
355-356: 51-59.
Köhler, S., Dufaud, F., and Oelkers, E. H., 2003. An experimental study of illite dissolution kinetics as a function of pH from
1.4 to 12.4 and temperature from 5 to 50℃. Geochimica et
Cosmochimica Acta, 67: 3583-3594.
Li, D. J., Zhang, J., Huang, D. J., Wu, Y., and Liang, J., 2002.
Oxygen depletion off the Changjiang (Yangtze River) Estuary.
Science in China (Series D), 45: 1137-1146.
Oelkers, E. H., and Poitrasson, F., 2002. An experimental study
of the dissolution stoichimetry and rates of a natural monazite
as a function of temperature from 50 to 230℃ and pH from
1.5 to 10. Chemical Geology, 191: 73-87.
Oelkers, E. H., Gislason, S. R., Eirĺksdóttir, E. S., Jones M. T.,
Pearce, C. R., and Jeandel, C., 2011. The role of riverine particulate material on the global cycles of the elements. Applied
Geochemistry, 26: S365-S369.
Oelkers, E. H., Jones, M. T., Pearce, C. R., Jeandel, C., Eiriksdottir, E. S., and Gislason, S. R., 2012. Riverine particulate
material dissolution in seawater and its implications for the
global cycles of the elments. Comptes Rendus Geoscience,
344: 646-651.
Oelkers, E. H., Schott J., and Devidal, J. L., 1994. The effect of
aluminum, pH, and chemical affinity on the rates of aluminosilicate dissolution reactions. Geochimica et Cosmochimica
Acta, 58: 2011-2024.
Parthasarathy, H., Dzombak, D. A., and Karamalidis, A. K.,
2013. A small-scale flow-through column system to determine the rates of mineral dissolution at high temperature and
pressure. Chemical Geology, 354: 65-72.
Pearce, C. R., Jones, M. T., Oelkers, E. H., and Pradoux, C.,
2013. The effect of particulate dissolution on the neodymium
(Nd) isotope and Rare Earth Element (REE) composition of
seawater. Earth and Planetary Science Letter, 369-370: 138147.
Ramos, M. E., Palma, S. G., Rozalena, M., Johnston, C. T., and
Huertas, F. J., 2014. Kinetics of montmorillonite dissolution,
424
GUO et al. / J. Ocean Univ. China (Oceanic and Coastal Sea Research) 2015 14: 417-424
An experimental study of the effect of oxalate. Chemical Geology, 363: 283-292.
Reitzel, K., Jensen, H. S., and Egemose, S., 2013. pH dependent
dissolution of sediment aluminum in six Danish lakes treated
with aluminum. Water Research, 47: 1409-1420.
Rozalen, M. L., Huertas, F. J., Brady, P. V., Cama, J., Garcia, S.,
and Linares, J., 2008. Experimental study of the effect of pH
on the kinetics of montmorillonite dissolution at 25℃. Geochimica et Cosmochimica Acta, 72: 4224-4253.
Saito, Y., Yang, Z. S., and Hori, K., 2001. The Huanghe (Yellow
River) and Changjiang (Yangtze River) deltas: A review on
their characteristics, evolution and sediment discharge during
the Holocene. Geomorphology, 41: 219-231.
Sverdrup, H., and Warfvinge, P., 1993. Calculating field weathering rates using a mechanistic geochemical model-PROFILE.
Applied Geochemistry, 8: 273-283.
Wang, B., 2006. Cultural eutrophication in the Changjiang
(Yangtze River) plume: History and perspective. Estuarine
Coastal and Shelf Science, 69: 471-477.
Wang, H., Yang, Z., Wang, Y., Saito, Y., and Liu, J. P., 2008.
Reconstruction of sediment flux from the Changjiang (Yangtze River) to the sea since the 1860s. Journal of Hydrology,
349: 318-332.
Yacoub, C., Miralles, N., and Vladerrama, C., 2014. Experimental study of mobility and kinetic characterization of trace
elements in contaminated sediments from a river basin in
Northern Peru. Human and Ecological Risk Assessment, 21:
828-844.
Yadav, S. K., Chakrapani, G. J., and Gupta, M. K., 2008. An
experimental study of dissolution kinetics of Calcite, Dolomite, Leucogranite and Gneiss in buffered solutions at temperature 25 and 5℃. Environmental Geology, 53: 1683-1694.
Yang, S. L., Belkin, I. M., Belkina, A. I., Zhao, Q. Y., Zhu, J.,
and Ding, P., 2003. Estuarine delta response to decline in
sediment supply from the Yangtze River: Evidence of the recent four decades and expectations for the next half-century.
Estuarine Coastal and Shelf Science, 57: 689-699.
Zhai, W., and Dai, M., 2009. On the seasonal variation of air-sea
CO2 fluxes in the outer Changjiang (Yangtze River) Estuary,
East China Sea. Marine Chemistry, 117: 2-10.
(Edited by Xie Jun)