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Article: Abnormally high ammonium of natural origin in a coastal aquifer-aquitard system in the pearl river delta, China

TitleAbnormally high ammonium of natural origin in a coastal aquifer-aquitard system in the pearl river delta, China
Authors
Issue Date2010
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/est
Citation
Environmental Science And Technology, 2010, v. 44 n. 19, p. 7470-7475 How to Cite?
AbstractHigh-nitrogen loadings of rivers and aquifers systems are a major concern because of potential effects on human health and water quality impacts such as eutrophication of lakes and coastal zones. This nitrogen enrichment is commonly attributed to anthropogenic sources such as sewage and agricultural and industrial wastes. The aims of this study were to delineate spatial distribution of groundwater ammonium in the coastal aquifer system in Pearl River Delta (PRD), China and to identify the origin of the abnormally high ammonium. A total of 40 boreholes were drilled to collect core samples of the aquitard and groundwater samples in the basal aquifer. The core samples were used for extraction of pore water for centrifugation and bulk chemical analyses in laboratory. Unlike previous studies which focused mainly on the aquifer, this study treated the aquifer-aquitard system as a hydrogeochemical continuum. The results show that the aquifer-aquitard system contains an exceptionally large total ammonium mass. Ammonium occurred at concentrations up to 390 mg/L in the basal sand Pleistocene aquifer 20-50 m deep, the largest concentration reported for groundwater globally. This ammonium was natural, areally extensive (1600 km 2) and originated in the overlying Holocene-Pleistocene aquitard and entered the aquifer by groundwater transport and diffusion. Total ammonium in the aquifer (190 × 10 6 kg) was exceeded by total ammonium in the aquitard (8600 × 10 6 kg) by a factor of 45. Much organic nitrogen remained in the aquitard available for conversion to ammonium. This natural ammonium in the aquifer was slowly transported into the PRD river channels and the estuary of the South China Sea. The rate of this contribution will likely be greatly increased by sand dredging in the river channels and estuary. Although the ammonium in PRD groundwater occurred in the largest concentrations and mass reported globally, the literature shows no reports of other delta aquitards having been examined for ammonium occurrence and therefore abundant ammonium formed in aquitards rich in organic matter may not be uncommon and this "geologic" source of ammonium may present a large and hitherto unappreciated source of nitrogen discharging to surface waters. © 2010 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/139152
ISSN
2015 Impact Factor: 5.393
2015 SCImago Journal Rankings: 2.664
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council
Hong Kong Special Administrative Region, ChinaHKU 702707P
HKU 703109P
China Geological Survey
Guangdong Geological Survey
"Sustainable Water Environment" Strategic Research Sub-Theme in HKU
Funding Information:

This study was supported financially by the General Research Fund of the Research Grants Council, the Hong Kong Special Administrative Region, China (HKU 702707P and HKU 703109P), China Geological Survey, Guangdong Geological Survey and "Sustainable Water Environment" Strategic Research Sub-Theme in HKU. We thank Bob Ingleton, Xingxing Kuang, Haipeng Guo, Kouping Chen, Ming Tang, Shubing Wang, Kanghong Ai, Pu Yao, and students from the research group headed by Jiaoyao Chen in Zhongshan University for assistance with field drilling and sampling. Yongqiang Zong and Guangqing Huang are thanked for sharing their knowledge on Quaternary geology.

References
Grants

 

DC FieldValueLanguage
dc.contributor.authorJiao, JJen_HK
dc.contributor.authorWang, Yen_HK
dc.contributor.authorCherry, JAen_HK
dc.contributor.authorWang, Xen_HK
dc.contributor.authorZhi, Ben_HK
dc.contributor.authorDu, Hen_HK
dc.contributor.authorWen, Den_HK
dc.date.accessioned2011-09-23T05:46:05Z-
dc.date.available2011-09-23T05:46:05Z-
dc.date.issued2010en_HK
dc.identifier.citationEnvironmental Science And Technology, 2010, v. 44 n. 19, p. 7470-7475en_HK
dc.identifier.issn0013-936Xen_HK
dc.identifier.urihttp://hdl.handle.net/10722/139152-
dc.description.abstractHigh-nitrogen loadings of rivers and aquifers systems are a major concern because of potential effects on human health and water quality impacts such as eutrophication of lakes and coastal zones. This nitrogen enrichment is commonly attributed to anthropogenic sources such as sewage and agricultural and industrial wastes. The aims of this study were to delineate spatial distribution of groundwater ammonium in the coastal aquifer system in Pearl River Delta (PRD), China and to identify the origin of the abnormally high ammonium. A total of 40 boreholes were drilled to collect core samples of the aquitard and groundwater samples in the basal aquifer. The core samples were used for extraction of pore water for centrifugation and bulk chemical analyses in laboratory. Unlike previous studies which focused mainly on the aquifer, this study treated the aquifer-aquitard system as a hydrogeochemical continuum. The results show that the aquifer-aquitard system contains an exceptionally large total ammonium mass. Ammonium occurred at concentrations up to 390 mg/L in the basal sand Pleistocene aquifer 20-50 m deep, the largest concentration reported for groundwater globally. This ammonium was natural, areally extensive (1600 km 2) and originated in the overlying Holocene-Pleistocene aquitard and entered the aquifer by groundwater transport and diffusion. Total ammonium in the aquifer (190 × 10 6 kg) was exceeded by total ammonium in the aquitard (8600 × 10 6 kg) by a factor of 45. Much organic nitrogen remained in the aquitard available for conversion to ammonium. This natural ammonium in the aquifer was slowly transported into the PRD river channels and the estuary of the South China Sea. The rate of this contribution will likely be greatly increased by sand dredging in the river channels and estuary. Although the ammonium in PRD groundwater occurred in the largest concentrations and mass reported globally, the literature shows no reports of other delta aquitards having been examined for ammonium occurrence and therefore abundant ammonium formed in aquitards rich in organic matter may not be uncommon and this "geologic" source of ammonium may present a large and hitherto unappreciated source of nitrogen discharging to surface waters. © 2010 American Chemical Society.en_HK
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/esten_HK
dc.relation.ispartofEnvironmental Science and Technologyen_HK
dc.subject.meshAmmonia - analysis-
dc.subject.meshChina-
dc.subject.meshFresh Water - chemistry-
dc.titleAbnormally high ammonium of natural origin in a coastal aquifer-aquitard system in the pearl river delta, Chinaen_HK
dc.typeArticleen_HK
dc.identifier.emailJiao, JJ:jjiao@hku.hken_HK
dc.identifier.authorityJiao, JJ=rp00712en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/es1021697en_HK
dc.identifier.pmid20806932-
dc.identifier.scopuseid_2-s2.0-77957334889en_HK
dc.identifier.hkuros192956en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77957334889&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume44en_HK
dc.identifier.issue19en_HK
dc.identifier.spage7470en_HK
dc.identifier.epage7475en_HK
dc.identifier.eissn1520-5851-
dc.identifier.isiWOS:000282209700048-
dc.publisher.placeUnited Statesen_HK
dc.relation.projectOrigin and evolution of abnormally high ammonium groundwater in the Pearl River Delta and its environmental impact-
dc.relation.projectGeneration and Migration of High-Salinity Groundwater in the Pearl River Delta-
dc.identifier.scopusauthoridJiao, JJ=7102382963en_HK
dc.identifier.scopusauthoridWang, Y=37027493100en_HK
dc.identifier.scopusauthoridCherry, JA=7202723359en_HK
dc.identifier.scopusauthoridWang, X=37027575200en_HK
dc.identifier.scopusauthoridZhi, B=25824540100en_HK
dc.identifier.scopusauthoridDu, H=37025835300en_HK
dc.identifier.scopusauthoridWen, D=25937048900en_HK

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