{"title":"Satellite-observed significant improvement in nearshore transparency of the Bohai Sea during pollution control","authors":"","doi":"10.1007/s13131-023-2180-z","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>The Bohai Sea (BS) is the unique semi-closed inland sea of China, characterized by degraded water quality due to significant terrestrial pollution input. In order to improve its water quality, a dedicated action named “Uphill Battles for Integrated Bohai Sea Management” (UBIBSM, 2018–2020) was implemented by the Chinese government. To evaluate the action effectiveness toward water quality improvement, variability of the satellite-observed water transparency (Secchi disk depth, <em>Z</em><sub>SD</sub>) was explored, with special emphasis on the nearshore waters (within 20 km from the coastline) prone to terrestrial influence. (1) Compared to the status before the action began (2011–2017), majority (87.3%) of the nearshore waters turned clear during the action implementation period (2018–2020), characterized by the elevated <em>Z</em><sub>SD</sub> by 11.6% ± 12.1%. (2) Nevertheless, the improvement was not spatially uniform, with higher <em>Z</em><sub>SD</sub> improvement in provinces of Hebei, Liaoning, and Shandong (13.2% ± 16.5%, 13.2% ± 11.6%, 10.8% ± 10.2%, respectively) followed by Tianjin (6.2% ± 4.7%). (3) Bayesian trend analysis found the abrupt <em>Z</em><sub>SD</sub> improvement in April 2018, which coincided with the initiation of UBIBSM, implying the water quality response to pollution control. More importantly, the independent statistics of land-based pollutant discharge also indicated that the significant reduction of terrestrial pollutant input during the UBIBSM action was the main driver of observed <em>Z</em><sub>SD</sub> improvement. (4) Compared with previous pollution control actions in the BS, UBIBSM was found to be the most successful one during the past 20 years, in terms of transparency improvement over nearshore waters. The presented results proved the UBIBSM-achieved remarkable water quality improvement, taking the advantage of long-term consistent and objective data record from satellite ocean color observation.</p>","PeriodicalId":6922,"journal":{"name":"Acta Oceanologica Sinica","volume":"183 1","pages":""},"PeriodicalIF":1.4000,"publicationDate":"2024-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Oceanologica Sinica","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s13131-023-2180-z","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"OCEANOGRAPHY","Score":null,"Total":0}
引用次数: 0
Abstract
The Bohai Sea (BS) is the unique semi-closed inland sea of China, characterized by degraded water quality due to significant terrestrial pollution input. In order to improve its water quality, a dedicated action named “Uphill Battles for Integrated Bohai Sea Management” (UBIBSM, 2018–2020) was implemented by the Chinese government. To evaluate the action effectiveness toward water quality improvement, variability of the satellite-observed water transparency (Secchi disk depth, ZSD) was explored, with special emphasis on the nearshore waters (within 20 km from the coastline) prone to terrestrial influence. (1) Compared to the status before the action began (2011–2017), majority (87.3%) of the nearshore waters turned clear during the action implementation period (2018–2020), characterized by the elevated ZSD by 11.6% ± 12.1%. (2) Nevertheless, the improvement was not spatially uniform, with higher ZSD improvement in provinces of Hebei, Liaoning, and Shandong (13.2% ± 16.5%, 13.2% ± 11.6%, 10.8% ± 10.2%, respectively) followed by Tianjin (6.2% ± 4.7%). (3) Bayesian trend analysis found the abrupt ZSD improvement in April 2018, which coincided with the initiation of UBIBSM, implying the water quality response to pollution control. More importantly, the independent statistics of land-based pollutant discharge also indicated that the significant reduction of terrestrial pollutant input during the UBIBSM action was the main driver of observed ZSD improvement. (4) Compared with previous pollution control actions in the BS, UBIBSM was found to be the most successful one during the past 20 years, in terms of transparency improvement over nearshore waters. The presented results proved the UBIBSM-achieved remarkable water quality improvement, taking the advantage of long-term consistent and objective data record from satellite ocean color observation.
期刊介绍：
Founded in 1982, Acta Oceanologica Sinica is the official bi-monthly journal of the Chinese Society of Oceanography. It seeks to provide a forum for research papers in the field of oceanography from all over the world. In working to advance scholarly communication it has made the fast publication of high-quality research papers within this field its primary goal.
The journal encourages submissions from all branches of oceanography, including marine physics, marine chemistry, marine geology, marine biology, marine hydrology, marine meteorology, ocean engineering, marine remote sensing and marine environment sciences.
It publishes original research papers, review articles as well as research notes covering the whole spectrum of oceanography. Special issues emanating from related conferences and meetings are also considered. All papers are subject to peer review and are published online at SpringerLink.
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