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Article: Physical-biological coupling in the Pearl River Estuary

TitlePhysical-biological coupling in the Pearl River Estuary
Authors
KeywordsAlgal blooms
Chlorophyll
Eutrophication
Pearl River Estuary
Phosphorus limitation
Sewage
Issue Date2008
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/csr
Citation
Continental Shelf Research, 2008, v. 28 n. 12, p. 1405-1415 How to Cite?
AbstractThe Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River. Processes in the estuary vary spatially and temporally (wet vs dry season). In the dry season at the head of the estuary, hypoxic and nearly anoxic conditions occur and NH4 reaches >600 μM, NO3 is ∼300 μM and nitrite is ∼60 μM indicating that nitrification and denitrification may be important dry season processes in the region extending 40 km upstream of the Humen outlet. There are very few biological studies conducted in this upper section of the estuary in either the dry or wet seasons and hence there is a need for further research in this region of the river. In the wet season, the salinity wedge extends to the Hongqimen outlet and oxygen is low (35-80% saturation). Nitrate is ∼100 μM, silicate ∼140 μM; and phosphate is relatively low at ∼0.5 μM, yielding an N:P ratio up to ∼200:1 in summer. Nutrients decrease in the lower estuary and primary productivity may become potentially P-limited. Eutrophication is not as severe as one would expect from the nutrient inputs from the Pearl River and from Hong Kong's sewage discharge. This estuary shows a remarkable capacity to cope with excessive nutrients. Physical processes such as river discharge, tidal flushing, turbulent dispersion, wind-induced mixing, and estuarine circulation play an important role in controlling the production and accumulation of algal blooms and the potential occurrence of hypoxia. Superimposed on the physical processes of the estuary are the chemical and biological processes involved in the production of the bloom. For example, the 100N:1P ratio indicates that P potentially limits the amount of algal biomass (and potential biological oxygen demand) in summer. While extended periods of hypoxia are rare in Hong Kong waters, episodic events have been reported to occur during late summer due to factors such as low wind, high rainfall and river discharge which result in strong density stratification that significantly dampens vertical mixing processes. Nutrient loads are likely to change over the next several decades and monitoring programs are essential to detect the response of the ecosystem due to the future changes in nutrient loading and the ratio of nutrients. © 2008 Elsevier Ltd. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/58583
ISSN
2015 Impact Factor: 2.011
2015 SCImago Journal Rankings: 0.999
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorHarrison, PJen_HK
dc.contributor.authorYin, Ken_HK
dc.contributor.authorLee, JHWen_HK
dc.contributor.authorGan, Jen_HK
dc.contributor.authorLiu, Hen_HK
dc.date.accessioned2010-05-31T03:32:54Z-
dc.date.available2010-05-31T03:32:54Z-
dc.date.issued2008en_HK
dc.identifier.citationContinental Shelf Research, 2008, v. 28 n. 12, p. 1405-1415en_HK
dc.identifier.issn0278-4343en_HK
dc.identifier.urihttp://hdl.handle.net/10722/58583-
dc.description.abstractThe Pearl River Estuary is a subtropical estuary and the second largest in China based on discharge volume from the Pearl River. Processes in the estuary vary spatially and temporally (wet vs dry season). In the dry season at the head of the estuary, hypoxic and nearly anoxic conditions occur and NH4 reaches >600 μM, NO3 is ∼300 μM and nitrite is ∼60 μM indicating that nitrification and denitrification may be important dry season processes in the region extending 40 km upstream of the Humen outlet. There are very few biological studies conducted in this upper section of the estuary in either the dry or wet seasons and hence there is a need for further research in this region of the river. In the wet season, the salinity wedge extends to the Hongqimen outlet and oxygen is low (35-80% saturation). Nitrate is ∼100 μM, silicate ∼140 μM; and phosphate is relatively low at ∼0.5 μM, yielding an N:P ratio up to ∼200:1 in summer. Nutrients decrease in the lower estuary and primary productivity may become potentially P-limited. Eutrophication is not as severe as one would expect from the nutrient inputs from the Pearl River and from Hong Kong's sewage discharge. This estuary shows a remarkable capacity to cope with excessive nutrients. Physical processes such as river discharge, tidal flushing, turbulent dispersion, wind-induced mixing, and estuarine circulation play an important role in controlling the production and accumulation of algal blooms and the potential occurrence of hypoxia. Superimposed on the physical processes of the estuary are the chemical and biological processes involved in the production of the bloom. For example, the 100N:1P ratio indicates that P potentially limits the amount of algal biomass (and potential biological oxygen demand) in summer. While extended periods of hypoxia are rare in Hong Kong waters, episodic events have been reported to occur during late summer due to factors such as low wind, high rainfall and river discharge which result in strong density stratification that significantly dampens vertical mixing processes. Nutrient loads are likely to change over the next several decades and monitoring programs are essential to detect the response of the ecosystem due to the future changes in nutrient loading and the ratio of nutrients. © 2008 Elsevier Ltd. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/csren_HK
dc.relation.ispartofContinental Shelf Researchen_HK
dc.subjectAlgal bloomsen_HK
dc.subjectChlorophyllen_HK
dc.subjectEutrophicationen_HK
dc.subjectPearl River Estuaryen_HK
dc.subjectPhosphorus limitationen_HK
dc.subjectSewageen_HK
dc.titlePhysical-biological coupling in the Pearl River Estuaryen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0278-4343&volume=28&spage=1405&epage=1415&date=2008&atitle=Physical-biological+coupling+in+the+Pearl+River+Estuaryen_HK
dc.identifier.emailLee, JHW: hreclhw@hku.hken_HK
dc.identifier.authorityLee, JHW=rp00061en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.csr.2007.02.011en_HK
dc.identifier.scopuseid_2-s2.0-46549085739en_HK
dc.identifier.hkuros154910en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-46549085739&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume28en_HK
dc.identifier.issue12en_HK
dc.identifier.spage1405en_HK
dc.identifier.epage1415en_HK
dc.identifier.isiWOS:000257620200002-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridHarrison, PJ=9533159800en_HK
dc.identifier.scopusauthoridYin, K=7101985944en_HK
dc.identifier.scopusauthoridLee, JHW=36078318900en_HK
dc.identifier.scopusauthoridGan, J=7102366816en_HK
dc.identifier.scopusauthoridLiu, H=8726071200en_HK

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