The spatial distribution of salinity in the Pearl River Estuary in China from space

Author(s):  
Zengzhou Hao ◽  
Qianguang Tu ◽  
Haiqing Huang ◽  
Difeng Wang ◽  
Yan Bai ◽  
...  
2020 ◽  
Vol 17 (3) ◽  
pp. 240 ◽  
Author(s):  
Chen He ◽  
Qiong Pan ◽  
Penghui Li ◽  
Wei Xie ◽  
Ding He ◽  
...  

Environmental contextEstuaries play an important role in global carbon cycling in terms of transforming dissolved organic matter (DOM). We describe the molecular composition and spatial distribution of DOM in the Pearl River Estuary, an area severely impacted by anthropogenic activities, and show how DOM composition gradually changes with salinity. The results will help our understanding of the sources and transformations of anthropogenic DOM discharged to the coastal seas. AbstractThe Pearl River is the second-largest river in China in terms of water discharge and brings enormous amounts of nutrients and terrestrial organic matter to the South China Sea, which makes the Pearl River Estuary (PRE) highly eutrophic. However, the molecular composition and distribution of dissolved organic matter (DOM) in the PRE have scarcely been investigated. In this study, solid-phase extraction (SPE) was performed to collect DOM samples from PRE along a salinity gradient. The samples were characterised by negative-ion electrospray ionisation (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to analyse their molecular composition and spatial distribution. The FT-ICR MS results showed that the terrestrial organic matter was gradually diluted and/or degraded during the migration from the river to the coastal ocean. Furthermore, both sulfur containing and unsaturated molecules were highly abundant in the upper stream samples, which indicated that anthropogenic input might be another important source of the assigned DOM in PRE. A group of bio-refractory molecules, characterised as carboxylic-rich alicyclic-like molecules, was found to accumulate with the increase of salinity. The composition of the SPE-DOM showed a gradual variation with the salinity and spatial changes; however, the variation was slightly different from those in pristine estuaries. This study demonstrates that the molecular composition of DOM is crucial for elucidating its source and transformation in an estuary.


Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1618
Author(s):  
Siyang Li ◽  
Yilin Wang ◽  
Lihong Liu ◽  
Houwei Lai ◽  
Xiancan Zeng ◽  
...  

This study conducted an analysis of microplastics (MPs) pollution in a coastal region of the Pearl River Estuary (PRE) in the South China Sea. The results show that the abundance of MPs during the rainy season reached 545.5 particles m−3, which was 1.85-fold higher than during the dry season. The spatial distribution of MPs also varied offshore in the following order: the river > estuary > sea. The average abundance of MPs in the river was 1.17-fold higher than that of the estuary and 4.65-fold higher than that of the marine environment. There were large amounts of gray, white, and green MPs, and about 53.5–73.9% of the MPs were less than 0.5 mm. The main forms of MPs were fibers, granules, fragments, and films. MPs composed of polyethylene accounted for 35.7–38.8%. PCA analysis showed that MPs carried by the river were an important source of MP pollution in the coastal waters.


2019 ◽  
Vol 29 (4) ◽  
pp. 861-875
Author(s):  
Zeyu Zeng ◽  
William W. L. Cheung ◽  
Shiyu Li ◽  
Jiatang Hu ◽  
Ying Wang

2021 ◽  
Vol 9 (2) ◽  
pp. 131
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.


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