Environmental Engineering Reference
In-Depth Information
I NTRODUCTION
Heavy metal pollution is a worldwide environmental problem. Superfluous heavy metals
added to water environment by human activities are harmful to health of biota because heavy
metals are toxic but not destructible, which will eventually influence the health of human by
food chain (Moore & Ramamoorthy 1985; Cheng 2002; Dalman et al. 2006; Yi et al. 2011).
Heavy metals are transported into water body, absorbed by suspended solids and finally
accumulated in the sediments as a sink and may turn as a source of pollutants forming a
heavy metal balance between water and sediment, which will pollute water persistently
(Hakanson 1980). Thus, Accumulation of heavy metals in the sediments can reflect the
sustaining quality of water ecosystem, and assessment of the ecological risk of heavy metals
in the sediments will give informative reference to environmental management.
Rapid industry development has been undergoing in China which will lead to
concomitant heavy metal pollution in water ecosystems (Cheng 2002; Shao et al. 2006). Most
of the industry parks are distributed adjacently to the main water ecosystems including coastal
zone, lakes and rivers, wetlands. And the industrial waste from these industry parks is poured
into these water bodies which would result in heavy metal pollution. Monitoring heavy metal
pollution of major water ecosystems in China has been conducted separately and many
studies reported that these water ecosystems had been polluted by heavy metals seriously (e.g.
Li et al. 2007; Li et al. 2008; Fu et al. 2009; Gan et al. 2010; Wang et al. 2011; Zheng et al.
2011). However, assessments of the potential ecological risk of heavy metal pollution in
water ecosystems of whole China have not been reported before.
Here, we collected the data of heavy metal concentrations from recent literatures and
assessed potential ecological risk of heavy metal pollution in water bodies of China and tried
to address the following questions. (i) What is the situation of heavy mental pollution in
sediments of water body in China? And which heavy metal pollutes water bodies most severe
across whole nation? (ii) What is the difference of heavy metal pollution in sediments of
water bodies among industrial districts in China? (iii)What is the difference of heavy metal
pollution among sediments of four water body types?
M ATERIALS AND M ETHODS
Data Collection
By conducting the study under the guidance of National Knowledge Infrastructure
(CNKI, In Chinese), Web of Science and retrieved the references cited in papers we build a
database. Heavy metals, water, sediment, river, lake, wetland, sea, pollution and China were
used as keywords in the searching process. We included data with the following criterion in
our analysis: water sediment, concentrations of heavy metals (As, Cd, Cr, Cu, Hg, Pb and
Zn), top layer (<20cm) and sampling time (2005~2011). As a result, concentrations of heavy
metals from 2367 samples were included in our analysis (Appendices Figure S1).
Additionally, we classified China into 7 industrial districts according to geographic locations,
administrative regions and major industrial types (Appendices Table S1). Dongbei is the
industrial base of China, which is famous for iron and steel industry, machinery industry, the
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