Abstract
Shenzhen Bay (SZB), situated between Shenzhen and Hong Kong, is a typical bay system. The water quality of the bay is notably affected by domestic and industrial discharge. Rivers and various types of drainage outlets carry terrestrial pollutants into SZB, resulting in elevated concentrations of nitrogen and phosphorous as well as relatively poor water quality. For over 200 years, Hong Kong has practiced oyster farming within brackish estuarine waters. Oyster farming is a type of mariculture which includes oyster breeding in oyster rafts. Remote sensing is a monitoring technique characterized by large spatial coverage, high traceability, and low cost, making it advantageous over conventional point-based and ship-borne monitoring methods. In this study, remote-sensing models were established using machine-learning algorithms to retrieve key water-quality factors (dissolved inorganic nitrogen (DIN) and orthophosphate-phosphorous (PO4_P) concentrations, CDIN and CPO4_P, respectively) from long-term time-series data acquired by the Landsat satellites. (1) Spatially, the water quality in Inner SZB was worse than that in Outer SZB. (2) The water quality temporarily deteriorated between the end of the 20th century and the beginning of the 21st century; then it gradually improved in the late 2000s. (3) Monitoring the water quality in an oyster-farming area revealed that oyster farming did not adversely affect the water quality. (4) The result of monitoring the water quality in river estuaries in SZB shows that water quality was mainly affected by river input.
Highlights
Bays are important areas for marine-based economic activity, tourism, and mariculture
(2) The water quality temporarily deteriorated between the end of the 20th century and the beginning of the 21st century; it gradually improved in the late 2000s
Corresponding radiance values in the remote-sensing images were matched based on the latitude and longitude of the HKEPD in situ data for Shenzhen Bay (SZB)
Summary
Bays are important areas for marine-based economic activity, tourism, and mariculture. These activities lead to pollution in bays [1], such as in Shenzhen Bay (SZB), a typical bay in the northern South China Sea between Shenzhen and Hong Kong. Domestic activities and industrial operations (e.g., wastewater discharge from large industrial enterprises, maritime shipping, and aquaculture) put enormous pressure on coastal waters [2]. The seawater quality in the western coastal waters near Shenzhen was lower than the Class IV standard of the Chinese Sea Water Quality Standard (GB 3097-1997) [3]. The government of Shenzhen has launched a campaign to reduce pollution levels in SZB, joining forces with the government of Hong Kong to restore the Shenzhen River—the largest river that empties into SZB [5]. Water-quality monitoring can facilitate assessment of the current status of SZB as well as provide an evaluation of the cleanup measures
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
