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Article: Speciation and mobility of heavy metals in mud in coastal reclamation areas in Shenzhen, China

TitleSpeciation and mobility of heavy metals in mud in coastal reclamation areas in Shenzhen, China
Authors
KeywordsHeavy metals
Land reclamation
Mobility
Mud
Sequential extraction
Speciation
Issue Date2007
PublisherSpringer Verlag. The Journal's web site is located at http://link.springer.de/link/service/journals/00254/index.htm
Citation
Environmental Geology, 2007, v. 53 n. 1, p. 221-228 How to Cite?
AbstractCoastal reclamation has been carried out along the coastal areas near Shenzhen, China in a large scale since 1980s by dumping fill materials over the marine mud at the sea bottom. Usually the area to be reclaimed is drained first and some of the mud is air-dried for a few weeks before it is buried by fill. After reclamation, the terrestrial groundwater, which is relatively acidic and with high dissolved oxygen, gradually displaces the seawater, which is alkaline with high salinity. The changes in the burial conditions of mud and the properties of the pore water in the mud may induce the release of some heavy metals into the mud. Field survey confirms that the pH and salinity of the groundwater in the reclamation site are much lower than the seawater. Chemical analyses of mud and groundwater samples collected from the reclamation sites reclaimed in different years indicate that most of the heavy metals in the mud decrease gradually with time, but the heavy metals in the groundwater are increased. The release of heavy metals into pore water due to reactivation of heavy metals in the mud is of environmental concern. To understand why some of the heavy metals can be released from the mud more easily than others, a sequential extraction method was used to study the operationally determined chemical forms of five heavy metals (Cu, Ni, Pb, Zn, and Cd) in the mud samples. Heavy metals can be presented in five chemical forms: exchangeable, carbonate, Fe-Mn oxide, organic, and residual. Ni and Pb were mainly associated with the Fe-Mn oxide fraction and carbonate fraction; Zn was mainly associated with organic fraction and Fe-Mn oxide fraction, while Cu and Cd were associated with organic fraction and carbonate fraction, respectively. If the residual fraction can be considered as an inert phase of the metal that cannot be mobilized, it is the other four forms of heavy metal that cause the noticeable changes in the concentration of heavy metals in the mud. On the basis of the speciation of heavy metals, the mobility of metals have the following order: Pb (36.63%) > Cu (31.11%) > Zn (20.49%) > Ni (18.37%) > Cd (13.46%). The measured metal mobility fits reasonably well with the degree of concentration reduction of the metals with time of burial observed in the reclamation site. © 2007 Springer-Verlag.
Persistent Identifierhttp://hdl.handle.net/10722/73002
ISSN
2011 Impact Factor: 1.127
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorHuang, Jen_HK
dc.contributor.authorHuang, Ren_HK
dc.contributor.authorJiao, JJen_HK
dc.contributor.authorChen, Ken_HK
dc.date.accessioned2010-09-06T06:47:07Z-
dc.date.available2010-09-06T06:47:07Z-
dc.date.issued2007en_HK
dc.identifier.citationEnvironmental Geology, 2007, v. 53 n. 1, p. 221-228en_HK
dc.identifier.issn0943-0105en_HK
dc.identifier.urihttp://hdl.handle.net/10722/73002-
dc.description.abstractCoastal reclamation has been carried out along the coastal areas near Shenzhen, China in a large scale since 1980s by dumping fill materials over the marine mud at the sea bottom. Usually the area to be reclaimed is drained first and some of the mud is air-dried for a few weeks before it is buried by fill. After reclamation, the terrestrial groundwater, which is relatively acidic and with high dissolved oxygen, gradually displaces the seawater, which is alkaline with high salinity. The changes in the burial conditions of mud and the properties of the pore water in the mud may induce the release of some heavy metals into the mud. Field survey confirms that the pH and salinity of the groundwater in the reclamation site are much lower than the seawater. Chemical analyses of mud and groundwater samples collected from the reclamation sites reclaimed in different years indicate that most of the heavy metals in the mud decrease gradually with time, but the heavy metals in the groundwater are increased. The release of heavy metals into pore water due to reactivation of heavy metals in the mud is of environmental concern. To understand why some of the heavy metals can be released from the mud more easily than others, a sequential extraction method was used to study the operationally determined chemical forms of five heavy metals (Cu, Ni, Pb, Zn, and Cd) in the mud samples. Heavy metals can be presented in five chemical forms: exchangeable, carbonate, Fe-Mn oxide, organic, and residual. Ni and Pb were mainly associated with the Fe-Mn oxide fraction and carbonate fraction; Zn was mainly associated with organic fraction and Fe-Mn oxide fraction, while Cu and Cd were associated with organic fraction and carbonate fraction, respectively. If the residual fraction can be considered as an inert phase of the metal that cannot be mobilized, it is the other four forms of heavy metal that cause the noticeable changes in the concentration of heavy metals in the mud. On the basis of the speciation of heavy metals, the mobility of metals have the following order: Pb (36.63%) > Cu (31.11%) > Zn (20.49%) > Ni (18.37%) > Cd (13.46%). The measured metal mobility fits reasonably well with the degree of concentration reduction of the metals with time of burial observed in the reclamation site. © 2007 Springer-Verlag.en_HK
dc.languageengen_HK
dc.publisherSpringer Verlag. The Journal's web site is located at http://link.springer.de/link/service/journals/00254/index.htmen_HK
dc.relation.ispartofEnvironmental Geologyen_HK
dc.subjectHeavy metalsen_HK
dc.subjectLand reclamationen_HK
dc.subjectMobilityen_HK
dc.subjectMuden_HK
dc.subjectSequential extractionen_HK
dc.subjectSpeciationen_HK
dc.titleSpeciation and mobility of heavy metals in mud in coastal reclamation areas in Shenzhen, Chinaen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0943-0105&volume=53 &issue=1&spage=221&epage=228&date=2007&atitle=Speciation+and+mobility+of+heavy+metals+in+mud+in+coastal+reclamation+areas+in+Shenzhen,+China+en_HK
dc.identifier.emailJiao, JJ:jjiao@hku.hken_HK
dc.identifier.authorityJiao, JJ=rp00712en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1007/s00254-007-0636-7en_HK
dc.identifier.scopuseid_2-s2.0-34547750936en_HK
dc.identifier.hkuros138081en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-34547750936&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume53en_HK
dc.identifier.issue1en_HK
dc.identifier.spage221en_HK
dc.identifier.epage228en_HK
dc.identifier.isiWOS:000248930300021-
dc.publisher.placeGermanyen_HK
dc.identifier.scopusauthoridHuang, J=18437040800en_HK
dc.identifier.scopusauthoridHuang, R=7402950523en_HK
dc.identifier.scopusauthoridJiao, JJ=7102382963en_HK
dc.identifier.scopusauthoridChen, K=16300521600en_HK
dc.identifier.citeulike1923084-

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