File Download
  Links for fulltext
     (May Require Subscription)
Supplementary

postgraduate thesis: Metal enrichment in the sediment profile of Deep Bay, Hong Kong

TitleMetal enrichment in the sediment profile of Deep Bay, Hong Kong
Authors
Issue Date2013
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Chau, K. [周國銓]. (2013). Metal enrichment in the sediment profile of Deep Bay, Hong Kong. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053424
AbstractDeep Bay is located in the northwestern coast of Hong Kong (HK), where brackish water from the Pearl River Estuary meets and interacts with fresh water from Shenzhen River and Yuen Long Creek. A review of published material in this study indicates rapid economic and industrial developments can be found in Hong Kong and Pearl River Delta (PRD) region in the last 60years, which would have contaminated the sediment in Deep Bay with heavy metals. To examine the nature of metal contamination history, two 2m-long sediment cores are collected from the mud flat of Deep Bay, and the chemical and physical properties of the sediment sequence analyzed. Small disturbance of sediment profile is observed by the fluctuation of 210Pb signal, and constant rate of supply (CRS) model is applied for the calculation of sedimentation rate which is estimated to be 1.82cm/year.137Cs dating resolves two peaks for the radionuclide at 28cm and 109cm, as well as the onset of excessive 137Cs activity at 135cm, which are connected to the Chernobyl accident in 1986 and the banning and beginning of atmospheric testing of nuclear weapons in 1963 and 1950 respectively. Particle size analysis shows the core sediments are predominantly silt (4-64μm) and clay(<4μm). Enrichment factor of metal concentration displays that Cd, Cr, Cu and Zn has been significantly enriched since the 1950s, and hence 3 phases of metal enrichment could be identified: 1) insignificant anthropogenic input in preindustrial period before 1950, 2) significant enrichment of metal from anthropogenic sources during industrial stage in HK from 1950 to 1980, and 3) a further increase of metal enrichment after the introduction of new town development in northwestern part of HK and Chinese economic reform since 1980. Among the metals in the sediments at depth over 70cm, Cu and Zn are found to be exceeded the Lower Chemical Exceedance Level of the sediment quality criteria given by the Hong Kong Environmental Protection Department; hence, the metals would impose threats to the natural environment once they are released back to water column by changes to physical conditions. To evaluate the extent of environmental threats, future studies could focus on the bioavailability of the metals and the interaction of metals in sediments and water with organisms in the ecosystem of Deep Bay.
DegreeMaster of Philosophy
SubjectContaminated sediments - China - Hong Kong.
Heavy metals - Environmental aspects - China - Hong Kong.
Dept/ProgramEarth Sciences
Persistent Identifierhttp://hdl.handle.net/10722/188305

 

DC FieldValueLanguage
dc.contributor.authorChau, Kwok-chuen.-
dc.contributor.author周國銓.-
dc.date.accessioned2013-08-27T08:03:32Z-
dc.date.available2013-08-27T08:03:32Z-
dc.date.issued2013-
dc.identifier.citationChau, K. [周國銓]. (2013). Metal enrichment in the sediment profile of Deep Bay, Hong Kong. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b5053424-
dc.identifier.urihttp://hdl.handle.net/10722/188305-
dc.description.abstractDeep Bay is located in the northwestern coast of Hong Kong (HK), where brackish water from the Pearl River Estuary meets and interacts with fresh water from Shenzhen River and Yuen Long Creek. A review of published material in this study indicates rapid economic and industrial developments can be found in Hong Kong and Pearl River Delta (PRD) region in the last 60years, which would have contaminated the sediment in Deep Bay with heavy metals. To examine the nature of metal contamination history, two 2m-long sediment cores are collected from the mud flat of Deep Bay, and the chemical and physical properties of the sediment sequence analyzed. Small disturbance of sediment profile is observed by the fluctuation of 210Pb signal, and constant rate of supply (CRS) model is applied for the calculation of sedimentation rate which is estimated to be 1.82cm/year.137Cs dating resolves two peaks for the radionuclide at 28cm and 109cm, as well as the onset of excessive 137Cs activity at 135cm, which are connected to the Chernobyl accident in 1986 and the banning and beginning of atmospheric testing of nuclear weapons in 1963 and 1950 respectively. Particle size analysis shows the core sediments are predominantly silt (4-64μm) and clay(<4μm). Enrichment factor of metal concentration displays that Cd, Cr, Cu and Zn has been significantly enriched since the 1950s, and hence 3 phases of metal enrichment could be identified: 1) insignificant anthropogenic input in preindustrial period before 1950, 2) significant enrichment of metal from anthropogenic sources during industrial stage in HK from 1950 to 1980, and 3) a further increase of metal enrichment after the introduction of new town development in northwestern part of HK and Chinese economic reform since 1980. Among the metals in the sediments at depth over 70cm, Cu and Zn are found to be exceeded the Lower Chemical Exceedance Level of the sediment quality criteria given by the Hong Kong Environmental Protection Department; hence, the metals would impose threats to the natural environment once they are released back to water column by changes to physical conditions. To evaluate the extent of environmental threats, future studies could focus on the bioavailability of the metals and the interaction of metals in sediments and water with organisms in the ecosystem of Deep Bay.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.source.urihttp://hub.hku.hk/bib/B50534245-
dc.subject.lcshContaminated sediments - China - Hong Kong.-
dc.subject.lcshHeavy metals - Environmental aspects - China - Hong Kong.-
dc.titleMetal enrichment in the sediment profile of Deep Bay, Hong Kong-
dc.typePG_Thesis-
dc.identifier.hkulb5053424-
dc.description.thesisnameMaster of Philosophy-
dc.description.thesislevelMaster-
dc.description.thesisdisciplineEarth Sciences-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b5053424-
dc.date.hkucongregation2013-

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats