International Journal of Geosciences, 2012, 3, 81-92
http://dx.doi.org/10.4236/ijg.2012.31010 Published Online February 2012 (http://www.SciRP.org/journal/ijg)
Geochemistry of Water and Suspended Particulate in the
Lower Yangtze River: Implications for Geographic and
Anthropogenic Effects
Xuyin Yuan1*, Jizhou Li1, Changping Mao2, Junfeng Ji2, Zhongfang Yang3
1College of Environment, Hohai University, Nanjing, China
2School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
3School of Earth Sciences and Resources, China University of Geosciences, Beijing, China
Received October 21, 2011; revised November 9, 2011; accepted December 8, 2011
ABSTRACT
The lower Yangtze River undergoes intense anthropogenic activities and various natural progress compared to the up-
per-middle reaches. We explore the aqueous geochemistry of ions and elements of suspended particulate in order to
recognize the effects of natural conditions and anthropogenic inputs on rivers. These results show that total dissolved sol-
ids of water in the lower Yangtze River are similar as those in the upper-middle reaches of mainstream, but higher in tribu-
taries. The major elements of suspended particulate in high-flow regime (HFR) have approximate concentrations with
those in low-flow regime (LFR). But remarkable high concentrations of trace elements in tributaries exhibit regardless
of HFR or LFR. Multivariate statistics show the suspended particulate matter (SPM) of mainstream presents similar
characteristics in flood season and diverse characteristics in dry season. While SPM of tributaries reveals different re-
sults. The majority of suspended matter originates from municipal and industrial discharge both in flood season and dry
season, and a part from road runoff in flood season, showing an effect of hydrological regime. Mining activity induces
remarkably high concentrations of metals regardless of HFR or LFR. Therefore, the geochemistry of SPM in the lower
reach of Yangtze River are significantly affected by the anthropogenic input of different sources, which is different
from the upper-middle Yangtze River.
Keywords: Suspended Particulate; Major Element; Trace Element; Hydrological Regime; The Yangtze River
1. Introduction
The Yangtze River as a lifeline and ecosystem is reported
to have degraded drastically during the recent decades.
Discharge of industrial wastes, the promoted application of
fertilizers, pesticides and herbicides in farming, as well as
heavy metal pollution are said to make it one of the most
polluted rivers in the world [1,2]. Meanwhile, the local
topography, hydrology and geology in the catchment areas
determine the wide range of water chemistry conditions
observed in streams. Anthropogenic activity may add con-
siderable amounts of pollution compounds, which will
influence the existing aquatic system [3]. A careful in-
vestigation of sources and geographic distribution of met-
als has provided evidences for their geogenic origin, and
also indicated tributaries be contaminated by human ac-
tivities [4]. The different hydrological conditions can
change the chemical properties of water and particulate,
which will also change the speciation of metals [5].
The lower reaches of the Yangtze River include the
important agricultural and industrial areas, and the eco-
nomic activities accelerate during recent decades. In its
lower part, the Yangtze River drains one of the most po-
pulated areas of the world and is also probably affected
by the Three Gorges Dam (TGD), which is located in the
middle part of this river. Meanwhile, the lower Yangtze
River and most of tributaries are close to the river mouth
and influenced by the tidal process. It is necessary to
investigate geochemistry of water and suspended matter
in mainstream and tributaries in the area.
Previous studies have shown the chemical composi-
tions of waters and particulate phases in the Yangtze Ri-
ver, but most sites discussed are located in the upper-
middle river [6-8]. Very few studies focus on chemical
compositions in different hydrological regime and the
relationships of components between mainstream and
tributary. Although the anthropogenic contributions to the
chemical composition of the dissolved load of the Yang-
tze basin rivers have been demonstrated in previous stud-
*Corresponding author.
C
opyright © 2012 SciRes. IJG

X. Y. YUAN ET AL. 82
ies [7,9], it was not explicitly assessed as an indicator of
environmental condition. The interactions of major and
trace elements are also absent in these studies, although it
is important for aqueous environment.
This paper describes the geochemical characteristics of
suspended particulate matter and their changes in differ-
ent environmental conditions under contrasting river
flows in the lower Yangtze River. We also compare the
chemical components of waters in lower reaches with
those in upper-middle reaches. Another important issue
we tackle in this study is the impact of human activities
on the particulate metal enrichments of the lower Yang-
tze basin in different time and space.
2. Study Area and Background
The lower Yangtze River is the section from Hukou at
Jiangxi-Anhui boundary to river mouth, where the plains
and low hills are dominant in the watershed (Figure 1).
The lower reaches cover the territory of Anhui Province,
Jiangsu Province and Shanghai City, which is one of
most dense population and rapidly economic develop-
ment areas in China. The lower Yangtze watershed is
mainly overlain by sedimentary rocks composed of ma-
rine carbonates, sandstone, siltstone and magmatic rocks,
metamorphic rocks from Precambrian to Quaternary, where
sedimentary rocks are the dominant rocks (limestone and
sandstone). The gneiss are distributed in the mountainous
areas of northern Anhui and granites are distributed in
hilly land of southern Anhui. In the southern of Jiangsu,
limestone and sandstone are widely spread over the hilly
land beside the river. The plain areas expose silty-clay,
loam soils and quaternary deposits.
The mainstream of research areas flows through sev-
eral large cities such as Anqing, Tongling, Wuhu, Nan-
jing and Nantong, and tributaries flow through different
topographies on the basis of position. The river mouth is
bifurcated by Chongming Island, and undergoes strong
tidal process. The tributaries include Wanhe River, Da-
sha River, Yuxi River, Jiajiang River, Qingtong River,
Shun’an River and Shuiyang River in the study area, and
the former four rivers are located in the south of the
Yangtze River and the latter three rivers are located in
the north side (Figure 1). The bedrocks on upper reaches
of Wanhe River are gneiss and granites, Tertiary sandsto-
ne and conglomerate on its middle reaches, laterite and
brown clay on its lower reaches. The geological setting
of Dasha River is similar with Wanhe River, but uplands
of metamorphic rock are distributed on its upper-middle
reaches, sandstone distributed on its lower reaches with
small scale volcanic rocks. The upper reaches of Qing-
tong River expose acid magmatic rocks, whose chemical
compositions are characteristic of near saturated SiO2, with
abundant Fe and S. Its middle and lower reaches are co-
vered by sedimentary rocks such as limestone and sand-
stone. The upper reaches of Shun’an River are near a
Cu-Au-bearing ore deposit occurring in carbonates of Car-
boniferous. A great amount of Fe-Mn oxides as ore-bear-
ing gangue are distributed around the mining area. The
Shuiyang River flows through an area with acid or neu-
tro-acid magmatic rocks on the upper reaches of south-
ern Anhui, and covers with red sandstone, conglomerate
regions on its middle and lower reaches. Wuhu City and
Xuanzhou City are located beside the river. The Yuxi
River is connected with an eutrophication lake—Chaohu
Lake, whose vicinity areas are Hefei City and Chaohu
City of Anhui province. The volcanic rocks and phospho-
rus-bearing carbonates are distributed on its western and
northern of the lake, and Mesozoic siltstone, sandstone
and Quaternary silty-clay cover the lower reaches [10].
The two sides of Jiajiang River expose the Quaternary
loose sediments. The river flows through Yanzhou City
and Taizhou City of Jiangsu province and is close to the
mouth of Yangtze River.
Figure 1. Map showing the research area and sampling sites.

X. Y. YUAN ET AL. 83
The water current of the lower Yangtze River is rela-
tively slow in base flow regime as result of flat topogra-
phy and wide water surface. The average flux of Datong
section, Nanjing section and river mouth are 2.90 × 103
m3·s–1, 2.94 × 103 m3/s and 3.2 × 103 m3·s–1 respectively.
Annual rainfall amount averages 1644 mm/year for the
lower reaches and 1396 mm/year for the middle reaches,
435 mm/year for the upper reaches of the Yangtze River
[2]. Surface runoff is the major water supply of the
Yangtze watershed, accounting for 70% - 80% of the
total water discharge [7]. Floods in the Yangtze basin are
formed by storms which are concentrated between May
and October. The temporal and spatial distribution of rain-
fall in the wet season directly influences amount, trans-
portation and chemical compositions of suspended par-
ticulate, which is apparently different from the dry season.
3. Sampling and Methods
Samples were collected in July-August 2008 and Janu-
ary 2009, when the Yangtze River encountered high-flow
and low-flow period in the research watershed. We col-
lected samples onboard in order to keep a normal hydro-
logic condition. Ten sampling sites were distributed in
mainstream and seven sampling sites in tributaries (Fig-
ure 1).
All collection buckets of polythene were cleaned by
rinsing with dilute nitric acid, pure water and the sample
water. Water was collected manually far from the river
bank in a 25 L acid-cleaned polypropylene. Samples were
filtered through pre-weighed 0.45 μm cellulose acetate
filters (Q/YY8-1-88, Shanghai) in the room within 24 h
after sampling. The vacuum pump was used to take out
air from the bottle containing water in order to accelerate
the filtration process. Suspended particulate depositing
on membrane was collected for analysis.
The membranes were dried before filtrating and wei-
ghted in 1/10000 balance for three times until the nume-
rical values were stable. After filtrating, these membranes
were dried and weighted in microbalance for three times.
The weight of membranes with SPM was reduced by the
same vacant membranes weighted before, and the total
contents of SPM can be obtained in sampled water. 1L
unfiltrated water was collected for aquatic chemical ana-
lysis.
Measurements of pH in the surface water were done
with a WTW profilLine 197 H-meter with a SenTix 21
probe. The unfiltrated water was determined for cations
and anions in order to discuss aquatic geochemistry of
rivers. The major elements Al, Fe, Ca, Mg, Na, K were
determined by Inductive Coupled Plasma-Atomic Emis-
sion Spectrophotometer (ICP-AES, Er/S, USA). The trace
elements Cr, Cu, Zn, Pb, Cd, Co, Ni, Se, Sc and Th were
determined by Inductively Coupled Plasma Mass Spec-
trometry (ICP-MS a Perkin Elmer, Elan 6000, USA) af-
ter addition of an indium internal standard solution. Ar-
senic (As) and Mercury (Hg) were determined by Atomic
Fluorescence Absorption Spectrophotometer (AFS-230E,
China).
River particulate from reference material GSS-15 (Na-
tional Standard Council of China) was digested and ana-
lyzed under the same conditions as the sample particu-
lates for both the major and trace elements. Differences
between measured and certified values were between 2%
to 6% for major elements, 4% - 11% for trace elements.
Also, analytical blanks always gave values less than 5%
of the measured contents.
4. Results
4.1. Compositions of Main Cation and Anion in
Water of the Lower Yangtze River
The ion compositions of water in river originated from
rock weathering and anthropogenic input, which can re-
flect characteristics of local environment. Of cations de-
tected, Ca2+ accounted for the highest proportion (61.4%
- 63.9%), following by Na+ (15.3% - 20.4%), Mg2+
(11.6% - 14.8%), K+ (3.7% - 6.1%). Overall, the con-
centrations of Ca2+ and Mg2+ in mainstream were slightly
higher than in tributaries. 3
displayed the highest
proportion in anions (56.1% - 69.0%), the other anions
descended in order of 4
SO (17.2% - 34.0%), Cl–
(5.6% - 8.7%) and 3 (1.5% - 8.1%). The minor F–
was less than 0.2% of total anions. The anions fluctuated
more significantly than cations, notably in tributaries. It
seemed the total dissolved solids (TDS) were similar
between high-flow regime (223 - 271 mg/L) and low-
flow regime (233 - 275 mg/L) in the mainstream of Yang-
tze River. But they were variable in tributaries (HFR, 104 -
363 mg/L, LFR 114 - 500 mg/L) (Table 1). Our data of
TDS showed higher concentrations than those from Chen
et al. (2002) (171.3 mg/L in Datong Station). It is evident
that TDS increases with the exploitation along the river
in couple of years.
HCO-
2-
2
SiO -
4.2. Major and Trace Elements of Suspended
Particulate in Mainstream
The major and trace elements of particulate are listed in
Table 2. Changes of particulate elemental concentrations
were significant between high-flow regime (HFR) and
low-flow regime (LFR). The concentrations of major
elements（Al, K, Na, Mg）of particulate in mainstream at
HFR were similar with those at LFR, but higher Fe and
lower Ca revealed at LFR. The average concentrations of
most trace elements were similar at HFR and LFR. But
higher P, Zn and Cr presented at LFR, and higher Cd
presented at HFR. The significant differences also pre-
sented in samples from different sites, which were asso-
ciated with mineral components and the geochemical pro-
perties of elements [11].

X. Y. YUAN ET AL. 84
Table 1. Ion compositions of natural water in mainstream and tributaries of the lower Yangtze River (mg/L).
Mainstream Tributary
high flow low flow high flow low flow
Range Average cv Range Averagecv Range Averagecv Range Averagecv
K+ 1.79 - 9.23 4.24 0.73 1.63 - 3.00 2.51 0.14 2.29 - 9.65 3.84 0.68 2.40 - 5.27 3.46 0.37
Na+ 4.60 - 18.5 10.8 0.44 4.56 - 17.2 13.8 0.26 5.45 - 23.1 11.4 0.58 5.17 - 25.1 13.6 0.62
Ca2+ 41.9 - 51.1 45.2 0.06 40.4 - 44.8 41.8 0.03 10.7 - 76.3 38.5 0.53 15.5 - 121 43.8 0.82
Mg2+ 8.15 - 12.9 10.4 0.12 7.42 - 10.1 9.38 0.08 3.81 - 12.4 8.92 0.31 3.93 - 12.0 8.01 0.43
2
4
SO -
3
HCO-
2
3
SiO -
20.4 - 34.6 31.1 0.13 22.6 - 43.1 39.5 0.16 8.90 - 119 39.4 0.91 12.5 - 277 65.4 1.13
Cl– 5.41 - 13.51 10.2 0.26 6.00 - 20.6 16.6 0.25 6.76 - 20.3 11.4 0.46 7.87 - 25.1 15.7 0.45
120 - 129 125 0.02 126 - 143 131 0.04 51.3 - 137 108 0.26 61.5 - 147 108 0.34
11.4 - 18.3 14.6 0.14 2.20 - 5.85 4.05 0.27 6.61 - 19.7 12.3 0.34 1.16 - 4.11 2.97 0.32
F– 0.15 - 0.25 0.21 0.16 0.14 - 0.30 0.28 0.18 0.17 - 0.38 0.27 0.36 0.19 - 0.51 0.31 0.44
cations 56.4 - 83.0 70.7 0.12 58.4 - 72.1 67.4 0.06 22.4 - 101 62.7 0.41 28.7 - 160 68.9 0.65
anions 167 - 188 181 0.03 174 - 202 192 0.04 81.2 - 262 172 0.33 85.7 - 340 178 0.49
TDS 223 - 271 251 0.05 233 - 275 259 0.05 104 - 363 234 0.35 114 - 500 247 0.53
pH 7.73 - 8.27 7.97 0.02 7.59 - 7.88 7.74 0.01 7.50 - 8.24 7.82 0.04 7.31 - 7.92 7.60 0.04
Table 2. Concentrations of major and trace elements in suspend ed particulate of mainstream (site = 10) and tributaries (site = 7).
Mainstream Tributary
high flow low flow high flow low flow
Items
Range Average cv Range AveragecvRange AveragecvRange Averagecv
As (mg/kg) 21.67 - 31.54 25.570.12 12.50 - 43.3627.890.3722.28 - 1438327.3 1.59 6.80 - 61.91 27.46 0.74
Hg 0.09 - 1.62 0.38 1.35 0.08 - 0.480.25 0.500.20 - 23.14 5.59 1.56 0.04 - 0.75 0.42 0.67
Pb 0.32 - 238.52 66.690.96 31.42 - 91.6168.920.2558.12 - 2193955.8 1.08 47.68 - 1584.9 298.601.90
Zn 123.31 - 237.74 177.80.17 119.5 - 354.7251.30.2671.49 - 1022575.280.64 197.5 - 3849 1205 1.21
Cu 5.98 - 97.50 65.860.40 38.31 - 125.078.290.2823.24 - 319.4187.860.54 51.47 - 806.8 246.0 1.09
Cd 0.65 - 19.98 2.97 2.01 0.52 - 2.271.52 0.350.11 - 34.15 6.64 1.83 0.72 - 57.88 12.78 1.65
Cr 87.49 - 165.9 128.90.16 129.8 - 376.2187.800.3772.53 - 1388519.040.92 152.7 - 316.3 202.1 0.28
Se 0.30 - 0.75 0.54 0.30 0.48 - 1.600.96 0.400.49 - 184.5 38.39 1.76 0.65 - 2.58 1.54 0.44
Co 18.53 - 38.90 23.770.24 14.66 - 28.1622.990.1510.62 - 68.7836.15 0.57 21.37 - 36.27 28.31 0.20
Ni 35.61 - 240.4 70.030.86 34.51 - 82.7163.440.2128.74 - 271.8135.120.72 56.98 - 256.7 98.79 0.72
Sc 11.88 - 51.28 19.3 0.60 9.87 - 19.6017.140.1610.38 - 91.4941.94 0.69 8.31 - 28.36 19.09 0.35
Th 6.57 - 17.69 14.010.22 11.60 - 22.4419.990.179.17 - 67.69 35.62 0.69 8.88 - 33.38 20.68 0.35
P 14.57 - 1063 800.80.37 611.02 - 31111551 0.47499.7 - 169597680 0.90 1433 - 14436 3946 1.18
Al (%) 8.36 - 9.83 9.16 0.05 8.16 - 10.669.68 0.079.23 - 11.85 10.48 0.09 9.93 - 12.36 11.21 0.07
Fe 3.43 - 5.76 4.71 0.15 3.10 - 7.085.52 0.194.49 - 8.14 6.09 0.24 5.91 - 9.79 7.55 0.17
K 1.55 - 2.61 2.22 0.15 1.55 - 2.812.41 0.141.46 - 3.04 2.18 0.26 1.55 - 3.81 2.44 0.30
Na 0.37 - 0.62 0.51 0.15 0.37 - 0.660.50 0.200.56 - 1.98 0.99 0.47 0.32 - 2.03 0.86 0.67
Ca 1.59 - 2.84 2.09 0.21 1.19 - 2.601.88 0.252.35 - 3.67 2.95 0.18 1.18 - 12.08 4.26 1.06
Mg 1.43 - 1.87 1.64 0.10 1.33 - 1.951.60 0.131.54 - 3.01 2.11 0.25 1.16 - 3.00 1.81 0.36
Unit in mg/kg for trace elements, % for Al, Fe, K, Na, Ca, Mg.

X. Y. YUAN ET AL. 85
4.3. Major and Trace Elements of Suspended
Particulate in Tributary
The major elements of suspended matter in tributaries
were slightly higher than in mainstream, especially at LFR.
Calcium showed remarkable high concentrations in sites
AH07 and AH10, which revealed the effect of urban ma-
terial [12]. The concentrations of trace elements in tribu-
taries fluctuate in a large scale, along with the ambient
circumstance. These elements in tributaries were evi-
dently elevated compared to those in mainstream. Con-
trasting with the mainstream, trace elements of particu-
late in tributaries are higher at LFR than at HFR, espe-
cially for the anthropogenic elements Cu, Pb, Zn, Cd, Ni.
Both major and trace elements were distinctive in dif-
ferent tributaries. Particulate Al and Fe were higher in
Wanhe River and Dasha River, which drained the meta-
morphic rock layer of mountainous areas in the upstream.
The high concentrations of metals appeared in the vicin-
ity of cities. Metal concentrations in Shun’an River showed
elevated values, notably for Cu, Pb, Zn, Cd and As. In
the high-flow period, the average metal concentrations of
particulate were the least in Jiajiang River. In the low-
flow period, Wanhe River showed the least average val-
ues of particulate metals. Mercury, Pb, Zn, Cd and As in
Dasha River and Shuiyang River at HFR were elevated,
and Hg and Pb were 1 - 2 grade higher than those in
other rivers. The highest Cd existed in Shun’an River,
and highest Cr in Wanhe River. At LFR, particulates in
Shun’an River are enriched in Cu, Pb, Zn, Cd and As.
Cadmium of particulates in Shun’an River and Qingtong
River was one grade higher than in other rivers. Particu-
late phosphorus at HFR was much higher than at LFR,
notably for Wanhe River and Yuxi River. Some elements
easily influenced by the weathering material such as Sc,
Th and Co also fluctuate obviously in two hydrologic
conditions, which suggest the natural input also make
important effects on the aqueous chemical compositions.
5. Discussion
5.1. Aqueous Geochemistry of the Lower
Yangtze River
Chemical components of riverine water consist of dissol-
ved and particulate matter, which originate from the sur-
rounding weathering rocks, soils and anthropogenic input.
Compared to the upper-middle Yangtze River, the lower
Yangtze River suffers from more intense human activi-
ties and tidal process. The ranges of TDS in high-flow
condition were 223 to 271 mg/L, average 251 mg/L. The
concentrations of TDS in low-flow condition were 233 to
275 mg/L, average 259 mg/L, which was slightly higher
than the average value 206 mg/L (ranging from 49.7 to
518.1 mg/L) of whole Yangtze River [7]. TDS in the main-
stream were similar at HFR and LFR. But they showed
more fluctuations in tributaries (104 - 363 mg/L at HFR,
114 - 600 mg/L at LFR). It is concluded that the chemical
components of main channel in the lower Yangtze River
are relatively stable and evidently affected by regional
geological setting, but the aquatic chemical components
of tributaries are markedly affected by anthropogenic
sources.
The median TDS concentration in Yangtze River is si-
milar to that of the Ganges- Brahmaputra in Asia and the
Mackenzie in North America, but is more than three times
the global median of 65 mg/l [13]. For most rivers in the
world, the enhanced dissolution of detrital calcite is likely
since suspended solid concentration in the flood season
can reach 6 - 55 times that in the dry season [14,15], but
there are no such large discrepancies in the lower Yang-
tze River between HFR and LFR. That is correlated with
plain terrain with mature soils in the research watershed.
The lowest values of TDS were observed in rivers drain-
ing mainly granitic and volcanic rocks in small basins
(Wanhe River). The highest values were observed in riv-
ers draining mainly sedimentary formations with metal
mines (Shun’an River).For rivers in the world, those wa-
ters draining silicate-rich bedrock were dominantly Na-
Cl in composition and had low total dissolved solids
(TDS 0.1 - 0.4 g/L). Those waters draining sedimentary-
rich bedrock were dominantly Na-Ca-Cl-3 in com-
position and had higher TDS (0.6 - 1.2 g/L) [16]. The
waters in the lower Yangtze River are of character for
these ions, but are lower concentrations of TDS.
HCO-
HCO-2-
2
SO -HCO-
HCO-2 SO -
Ca2+ was the main cation in the lower Yangtze River,
K+ and Na+ varied significantly ,but Mg2+ was relatively
less fluctuated. Compared with the upper-middle Yang-
tze River, the lower reaches showed lower Mg2+ and hi-
gher K+ + Na+. In contrast to cations, anions didn’t show
significant fluctuation, except a few samples. The con-
centrations of 3 and H2SiO3 were lower, 4 SO
and Cl– were higher here compared to the upper-middle
Yangtze River [7]. The aqueous geochemistry of tribu-
taries is influenced evidently by anthropogenic input in
the study area (Figures 2 and 3).
For the mainstream, the ion plots showed remarkable
diversities in Figure 2. Na+ and Cl– fluctuated sharply
and 4 and 3 changed moderately. Ca2+ and
Mg2+ maintained relatively steady contents. The ion con-
centrations of water at HFR were lower than at LFR.
Mg2+, 3 and 4 increased slightly at LFR.
This is associated with decreasing suspended particulate,
which reduces the adsorption on ions [17]. Na+ and Cl–
increase substantially as a result of the intrusion of
brackish water.
The tributaries are located in the different small wa-
tersheds and receive multi-source matter. So the plots dis-
persed in the figures, which were related with geological
setting, tidal process and anthropogenic activities (Figure
3). Samples of Wanhe River were situated in the up-
stream of Datong hydrologic station (the farthest site tide

X. Y. YUAN ET AL. 86
Figure 2. Diagram of cations and anions for mainstream at HFR and LFR in the lower Yangtze River. High-flow regime is
displayed by closed circle, Low-flow regime is displayed by open circle.
Figure 3. Diagram of cations and anions for tributaries at HFR and LFR in the lower Yangtze River. Closed circle represents
high-flow regime; Open circle represents low-flow regime.

X. Y. YUAN ET AL. 87
can reach), which had elevated Ca2+, Mg2+ and low Cl–,
Na+. The concentration of Mg2+, Ca2+, 4 and
3 in Shun’an River were significantly higher than
in other tributaries. Because the upstream of the river
was located in a mining area and the parent rocks with
ores were carbonates. The Jiajiang River had evident
high Na+ and Cl–, due to the close site to the river mouth.
2
SO -
HCO-
2
SO -
The plots of samples in tributaries were scattered in
Figure 3, which were associated with geographical and
external input. The high concentration sample of Ca2+,
Mg2+ and 4
were collected in a river impacted by
mining activity (Shun’an River, AH07), which showed
slight influence for different hydrological regimes. The
samples of high Na+ and Cl– concentrations were located
near by the city (AH03), or close to the river mouth (AH
10, JS03). Moreover, these sites revealed variable ion con-
tents at HFR and LFR.
5.2. Distribution and Accumulation of Trace
Elements in Suspended Particulate
As motioned above, the concentrations fluctuated obvi-
ously for most elements in different hydrological regimes.
The concentrations of particulate trace elements were a
little higher at LFR than at HFR for most samples of
mainstream. And Cd and Pb displayed remarkable chan-
ges at HFR, P and Cr were shifty elements at LFR.
The concentrations of trace elements in tributaries pro-
minently changed. Those elements influenced slightly by
human activities (Sc, Th, Se, Co) also revealed obvious
fluctuations in different sites, which were influenced by
local rocks and soils. The changes in the concentrations of
Cu, Pb, Zn, Cr, As and P observed at HFR and LFR may
be due to adsorption onto a variety of metal-bearing (espe-
cially Al, Fe and Mn) oxide and hydroxide minerals [18].
The enrichment ratio can reflect the accumulation de-
gree of trace elements in rivers. Based on the background
value of trace elements (Cu, Pb, Zn, Cr, Cd, As, Ni, P) in
sediment of the lower Yangtze River [19], we calculate
the enrichment factor (EF) of each element in suspended
particulate. Then we plus all EFs of eight elements to get
total enrichment factor (TEF). The formula is expressed
as follows.
EF
ii
MM, TEFΣEF
b i
==
where Mi is the concentration detected for one metal, and
Mb is the background value of the metal in the lower
Yangtze River. TEF is total value of eight enrichment fac-
tors.
The enrichment factors of eight trace elements were
showed in Figure 4. These factors of trace elements for
most sites were higher at LFR than at HFR, especially for
phosphorus. It was indicated most elevated elements from
anthropogenic activities had been mixed and diluted by
matter from geological clastics. But the enrichment fac-
tors of Cd, Ni and Pb at individual sites (AH11 and JS01)
were evidently larger at HLR than at LFR. They were
apparently related with the industrial discharge from sur-
rounding cities.
Obvious diversities of elemental enrichment appeared
in tributaries. Contrary to elements in mainstream, the en-
richment factors of most elements were higher at HFR in
tributaries, especially for As, Pb and Cr. The enrichment
factors of trace elements in Shun’an River at LFR were
higher than at HFR, as a result of influence by mining
discharge. The elevated trace elements at HFR were de-
duced from runoff of surrounding cities [20].
Figure 5 showed the distribution of TEFs in suspended
particulate of different sites. Two curves in the same dia-
gram represented samples collected at HFR and LFR.
TEFs of most samples were affected by the hydrological
regime. Samples at LFR showed higher TEFs in most
mainstream sites. But a few samples in same sites showed
a little difference at HFR and LFR like Site AH06 and
AH08. The two sites were distributed in rural area and
far away from the tributary, which indicated the external
input was significant for metal enrichment. Site AH11
showed much enriched for trace elements at HFR due to
inputs of two tributaries in flood season. The changes of
JS06 revealed a higher enrichment at HFR, showing in-
fluence of urban runoff from Suzhou and Shanghai. Oth-
erwise, the river mouth undergoes an intense mixture
between fresh water and salty water. The relatively low
concentrations of trace elements originated from dilution
of sea water [21].
For tributaries, the significant diversities existed at HFR
and LFR. Site AH02 and AH03 showed (Wanhe River
and Dasha River) high enrichment factors of Pb, As and
Cr at HFR, which were associated with basic metamor-
phic rocks in this watershed. This is a hilly area where
soils will be eroded easily. Site AH07 (Shun’an River)
displayed high enrichment factors of Cd, Pb, Zn and Cu
at LFR, indicating the influence of mining. Yuxi River
(AH10) was enriched in P, Pb, Zn and Cr at HFR, which
received great amount of domestic discharge from Lake
Caohu (upstream). The low TEFs appeared at Jiajiang
River and Shuiyang River (AH09 and JS03) of plain area
and rural area, which have received less eroded material
from lands and direct pollutant discharge.
5.3. Multivariate Statistics of Chemical
Compositions in Mainstream and Tributaries
5.3.1. Cluster Analysis
We can recognize the characteristics of sample and ele-
ment assembly by cluster analysis (CA) of chemical com-
positions. Q-type cluster analysis of twenty three compo-
nents was performed and results were showed in Figure
6. Most samples were classified as a similar group in Fig-
ure 6(a), which suggested chemical compositions of parti-
culate were relatively stable in mainstream in flood season.

X. Y. YUAN ET AL. 88
Figure 4. Diagrams showing enrichment factors of trace elements in different sites.
Figure 5. Total enrichment factors of seven trace elements for mainstream and tributary.

X. Y. YUAN ET AL. 89
Figure 6. Q-type cluster analysis of samples from mainstream and tributary. (a) Samples of mainstream at HFR; (b) Samples
of mainstream at LFR; (c) Samples of tributary at HFR; (d) Samples of tributary at LFR.
The site AH11 was affected by tributary input of Yuxi
River and Shuiyang River, which was different from other
samples. But sample sites can be divided into three groups
at dry season based on the correlation distance. The site
AH04 was influenced by Wanhe River and Dasha River.
Sample sites of tributaries showed an inverse trend com-
pared to mainstream. Samples of tributaries at flood sea-
son showed several groups with the correlation distance,
which were associated with local geological and anthro-
pogenic sources. Most samples of dry season were clas-
sified as a group expect AH10, showing less input from
watershed. Sample AH10 showed high P, Al, Fe and Mn,
indicating suspended matter from Lake Caohu [22].
5.3.2. Primary Component Analysis of Elements in
Two Seasons
Primary component analyses of 23 elements of samples
were manipulated for HFR and LFR.
Factor scores by rotating were showed in Table 3. Ba-
sed on the eigenvalue of exceeding 1, four factors were
acquired at HFR. The eigenvalues of factor were 13.2,
2.3, 2.0 and 1.0, which accounted for 62.9%, 10.8%,
9.7% and 4.9% variance for first to fourth factor respect-
tively.
According to elemental group of factor score, the first
factor was explained as matter from the municipal and
industrial sources (including mining). The second factor
showed a geological source. The third factor reflected
matter from road runoff [23], and the fourth factor repre-
sented source of upstream. It is evidently the municipal
and industrial sources are dominant.
Three factors were acquired at LFR. The eigenvalues
of factor were 8.7, 7.4 and 1.8, which accounted for 41.6%,
35.2% and 8.6% variance for first to third factor respect-
tively. The elemental groups were explained as industrial,
municipal and geological sources in order. The variance
percentages were similar for first factor and second fac-
tor, reflecting both as dominant sources at LFR.
Particulate sources showed differences at HFR and LFR.
Frequent rainfall induced mixing of the municipal and in-
dustrial discharge, which occupied majority of external
particulate in flood season. And particulate from upstream
also appeared in the research area. But the dry season lack
a great amount of flow, material from municipal and in-
dustrial discharge can be discriminated. Less road deposit
was washed out as a result of rarely raining in dry season.
5.4. The Effects of Geological and
Anthropogenic Characteristics on
Geochemical Components in the
Lower Yangtze River
The present researches suggest that the pH makes a sig-
nificant effect on the distributions of metals in suspended
solid [24]. In our research, the pH values were 7.73 -
8.24 at HFR, 7.59 - 7.88 at LFR for mainstream of the
lower Yangtze River, 7.50 - 8.24 at HFR, 7.31 - 7.92 at
LFR for tributaries. It is obvious that pH of water at LFR
is lower than that at HFR in this watershed, and pH of
tributary water is lower than that of mainstream. The
lower pH of water may result from anthropogenic matter
such as industrial discharge [25].

X. Y. YUAN ET AL. 90
Table 3. Primary component analysis of elements and factor scores for suspended particulate matter in two seasons.
Elements Samples in flood season Samples in dry season
Factor 1 Factor 2 Factor 3 Factor 4 Community Factor 1 Factor 2 Factor 3 Community
As 0.704 0.916 0.544 0.704
Hg 0.659 0.860 0.862 0.796
Se 0.722 0.920 0.747 0.790
Mo 0.915 0.924 0.960 0.943
Na 0.661 0.898 0.869 0.894
Mg 0.841 0.806 0.895 0.814
K 0.849 0.886 0.874 0.836
Ca 0.770 0.828 0.935 0.960
Al 0.817 0.868 0.714 0.854
Fe 0.918 0.917 0.745 0.931
Mn 0.665 0.828 0.569 0.720
Ni 0.911 0.852 0.957 0.957
P 0.867 0.867 0.948 0.961
Zn 0.893 0.960 0.819 0.854
Sc 0.916 0.944 0.863 0.957
Cr 0.907 0.836 0.577 0.337
Co 0.930 0.965 0.679 0.909
Cu 0.728 0.907 0.954 0.985
Cd 0.887 0.838 0.909 0.972
Pb 0.866 0.907 0.916 0.943
Th 0.853 0.802 0.823 0.805
Ca2+ of water is higher and Mg2+ is similar in mainstream,
K+ and Na+ are higher in the river mouth compared to the
data from Chen et al. (2002). Most anions such as
3 in the lower reaches are less than those in the
upper-middle reaches. But 4 increases in the lower
reaches, which originates from anthropogenic input [26].
Cl– is elevated in the upper Yangtze River (influenced by
evaporation rocks), decreases in the middle reaches and
lowest at Datong station in the lower reaches [7]. But it
increases toward the river mouth, showing the effect of
blackish water. H2SiO3 is extraordinary in the lower rea-
ches, which is 3 - 5 times at HFR than at LFR, even if in
tributaries. It is deduced that the material with high
H2SiO3 input by the runoff at HFR.
HCO-
2
SO -
HCO-
The rivers flowing through volcanic and metamorphic
rocks areas (Wanhe River and Dasha River) show a low
concentration of Ca2+. If rivers flow through carbonate
rocks areas (Qingtong River and Yuxi River), Ca2+ in-
creases significantly. The changing trend of 3 is
similar with that of Ca2+. H2SiO3 shows significant chan-
ges in tributaries, which is consistent with the distribu-
tion of background rocks. SO is a relative steady
component (except Shun’an River) although it increases
slightly with anthropogenic input in the study area. Most
of cations show slight fluctuations in rivers, but Na+ and
Ca2+ reveal different concentrations in tributaries. In
Shun’an River, Ca2+ is 2 - 3 fold larger than other rivers,
because its upper stream receives the discharge from a
mining region with carbonate bedrock. The high concen-
trations of Cl– in tributaries should originate from an-
thropogenic input, other than brackish water. Cl/Na in
most samples are more than 1, which shows a obviously
effect by agricultural and industrial dust [26,27], espe-
cially remarkably at LFR.
2
4
-
As mentioned above, the anthropogenic inputs take a
relatively weak effect on major elements and trace ele-
ments of suspended particulate in mainstream, but a strong
effect on those in tributaries. The concentrations of Pb
are significantly elevated at HFR. It is deduced that par-
ticulate Pb from road dusts enters rivers with runoff in
flood season, which is associated with rainstorm. Sus-
pended particulate shows high concentrations of Cu, Zn
and Cd in Shun’an River, which flows through a mining
area. Phosphorus is correlated with the discharge of do-
mestic sewage, which reveals high concentrations of par-
ticulate phase at HFR, and low concentrations at LFR,
especially for samples in Dasha River, Wahe River and
Yuxi River. As a rule, the concentration of Hg is essen-
tial constant in most studied rivers, but it increases rap-
idly in some sites nearby big cities (such as Nanjing and

X. Y. YUAN ET AL. 91
Wuhu). It is contributed by industrial discharge. There-
fore, trace elements in the tributaries are significantly af-
fected by anthropogenic inputs.
6. Conclusions
According to the chemical components of water and sus-
pended particulate, the remarkable differences present in
suspended particulate and the slight differences display
in water of the lower Yangtze River. The concentrations
of dissolved solids are mainly affected by the geographi-
cal location. The aqueous chemistry of mainstream shows
a major geological origin, following by the tidal process
and input of tributaries. It is evident that TDS increases
in the research watershed compared to data several years
ago, which is related in industrial and municipal dis-
charge.
The major elements and trace elements are enriched in
suspended particulate of tributaries in usual circumstan-
ces. And polluted elements in tributaries are obviously
several times higher than those in mainstream, indicating
more contaminants from human activities. Trace elements
in mainstream show small fluctuation of suspended par-
ticulate in flood season, due to dilution of large water
yield on external matter. But the concentrations of trace
elements are elevated in dry season. The accumulation of
trace elements is mainly influenced by the hydrological
condition in mainstream, but by anthropogenic input in
tributary. Primary components analysis of elements at
HFR and LFR shows the industrial and municipal dis-
charge is the origin of elemental enrichment for sus-
pended particulate in the lower Yangtze River.
As a whole, the geochemical components in the lower
Yangtze River are affected by the anthropogenic input,
geographical location and tide process, which is different
from the upper-middle Yangtze River.
7. Acknowledgements
The authors will deliver their appreciation to Dr. Yin-
xian Song, Tong He and Bing Li for their help in sample
collecting. This work is supported by the public welfare
fund of Ministry of Land and Resources of China (12108
20109, 201111021).
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