Radium isotopes assess water mixing processes and its application in the Zhujiang River estuary

• Published in: Chinese journal of oceanology and limnology Vol. 35; no. 5; pp. 1108 - 1116
• Main Author: 郭肖伊 许博超 于志刚 李秀芹 南海明 简慧敏 江雪艳 刁少波 高茂生
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.09.2017; Springer Nature B.V
• Subjects: 226Ra; Brackishwater environment; Chemical elements; Chemistry; Chlorophyll; Chlorophyll a; Dilution; Dynamics; Earth and Environmental Science; Earth Sciences; Ecological effects; Estuaries; Estuarine dynamics; Estuarine environments; Flow rates; Flow velocity; Hydrology; Isotopes; Light penetration; mass transfer; Mass transport; Mineral nutrients; Mixing; Mixing processes; Nutrients; Oceanography; Particulate matter; particulates; Primary production; primary productivity; radionuclides; Radium; Radium 226; Radium isotopes; Radium radioisotopes; River mouth; River mouths; River plumes; River water; Rivers; Seasons; Spatial distribution; Summer; Surface water; Suspended particulate matter; Transport; Water mixing; Water resources; Water transport; Winter; 叶绿素a浓度; 应用; 水文参数; 混合; 珠江口; 评估过程; 镭同位素; Pearl River Estuary; radium isotopes; water ages; Zhujiang River estuary; nutrients
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-017-6069-6

Radium （Ra） isotopes are useful for tracing water mass transport and examining estuarine hydrological dynamics. In this study, several hydrological parameters, nutrients, ehlorophyll-a （ehl-a）, suspended particulate matter （SPM） and Ra isotopes （223Ra, 224Ra and 226Ra） of surface waters of the Zhujiang （Pearl） River estuary （ZRE） were measured. This was done for both winter （December） and summer （July） seasons, to quantitatively understand the seasonal characteristics of river plume flow rate and trajectories, as well as the ecological response. The results show that Ra concentrations in summer were higher than in winter, especially Z24Ra （about 2-5 times higher）. The spatial distribution of three Ra isotopes and relative Ra water ages indicated that river water mainly flushed out of ZRE through the western side in winter, where the water transport was about 5 days faster than in the eastern zone. In summer, diluted river water expended to the east side, resulting in fairly similar water ages for both sides of the river mouth. Although nutrients were higher during the summer season, lower chl-a concentrations indicated that reduced primary production might be caused by high SPM （low light penetration）. The results obtained from this study will provide knowledge needed for effectively developing and managing the ZRE.