Groundwater and Nutrient Discharge into Jiaozhou Bay,North China |
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Authors: | G Q Liu S Y Wang X J Zhu S M Liu J Zhang |
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Institution: | (1) College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China;(2) College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, 266100, China;(3) State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China |
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Abstract: | The health of near shore marine ecosystems has long been a concern because of its importance to coastal areas. Jiaozhou Bay
(JZB) is one such marine ecosystem experiencing rapid water quality degradation in the last several decades. From the area
surrounding the bay, the nutrients discharged into the bay through surface water and groundwater has been greatly changed.
The thickness of the aquifers and the permeability is relatively high, the concentrations of nutrients in the groundwater
are generally high, and so the groundwater discharged into JZB is very significant. However, no attempt has ever been made
to evaluate the amount of nutrients discharged into the bay area via groundwater. In this study, the cross-section method
and water balance method were used to estimate the amount of groundwater and nutrients discharged into JZB via the subsurface.
Groundwater was monitored and sampled at aquifers surrounding the bay area, and some previously available data was also analyzed.
The results indicated that groundwater from the Baisha Aquifer east of JZB now is the major source of nutrients (nitrate,
dissolved SiO2) being discharged into the bay. The concentrations of nutrients in the groundwater have been increasing with intensive agricultural
land use. However, Dagu Aquifer, the largest aquifer north of JZB, only provides limited nutrients to the bay area because
of the construction of a low permeability subsurface dam. Historically, during the 1970s to the 1990s, the Baisha Aquifer
experienced seawater intrusion due to excessive groundwater withdrawal. The same was true for the Dagu Aquifer from the 1980s
to the 1990s. Because of this, no significant nutrients were discharged into the bay. |
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Keywords: | Groundwater discharge Nutrients Cross-section method Water balance method Jiaozhou Bay |
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