the pearl river
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2022 ◽  
Vol 8 ◽  
Author(s):  
Cui-Ci Sun ◽  
Wei-Zhong Yue ◽  
You-Shao Wang ◽  
Wei-Hong He ◽  
Yi-Guo Hong ◽  
...  

Distributions of Coomassie Blue stainable particles (CSP), the sources and transports, as well as their implications for nitrogen biogeochemical cycles in the Pearl River estuary (PRE) were investigated during two cruises in August 2016 and January 2017. CSPcolor concentrations (CSP concentration determined spectrophotometrically) were 73.7–685.3 μg BSA eq L–1 [μg Bovine serum albumin (BSA) equivalent liter–1] in August 2016 and 100.6–396.4 μg BSA eq L–1 in January 2017, respectively. CSP concentrations were high in low-salinity waters (<5), and declined from the river to the middle estuary by 80% in the wet season and 55.6% in the dry season, respectively, then increased again in the lower estuary due to high primary production. CSP concentrations were mainly associated with chlorophyll a (Chl a) concentration except for the turbid mixing zone, suggesting that autochthonous phytoplankton production served as the primary source of CSP in the PRE. The concentrations of nitrogen (N) as CSP in the PRE were comparable to the nitrogen content of particulate hydrolysable amino acids (PHAA). Pictures of CSP taken by microscopy and the correlation between composition of PHAA and the ratio of Chl a/CSPcolor showed that CSP were relatively degraded due to delivery of old terrestrial protein to river section and extensive microbial degradation during mixing at the upper and middle parts of the estuary, whereas CSP in lower estuary appeared to be more labile due to higher fresh algal production. The contribution of CSP nitrogen (CSP-N) to the particulate nitrogen (PN) pool was 34.98% in summer and 30.8% in winter. The conservative estimate of CSP-N input flux in the Pearl River Delta was about 6 × 106 mol N d–1. These results suggested that CSP was a significant pool of organic nitrogen in the PRE. The study of CSP composition in terms of nitrogen provides new insight into the roles of CSP on nitrogen biogeochemical processes in the turbid and productive estuarine system.


Water ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 90
Author(s):  
Zhiyuan Han ◽  
Huaiyuan Li ◽  
Hualiang Xie ◽  
Bing Yan ◽  
Mingxiao Xie

Based on mass bathymetric data and remote sensing data in the Modaomen Estuary, this study explored the long-term evolutionary characteristics of the mouth bar in the Modaomen Estuary of the Pearl River from 1964 to 2019. In the past 55 years, due to the impact of human activities, such as shoal reclamation and estuarine regulation in the Modaomen Estuary, the river mouth moved out of the shallow sea covered by several islands and faced the South China Sea directly. Therefore, the mouth bay became a siltation center in the estuarine region and expanded outwards, gradually evolving a geomorphic pattern with three shallow shoals and two distributary branches; a west branch as the main branch accompanied by a small east branch. Over the past decade, high-intensity sand dredging activities in the mouth bar have led to a considerable deepening of the water depth and a significant refinement of bed sediments, forming a discharge pattern of a wide and shallow channel flowing into the sea. Therefore, the evolutionary characteristics of the mouth bar have become abnormal in recent years, so additional field bathymetric data and hydrological data are required for further research regarding the subsequent evolution of the mouth bar, against the background of a significant reduction of sediment discharge and high-intensity human activities.


2022 ◽  
Vol 355 ◽  
pp. 02049
Author(s):  
Yufeng Shi ◽  
Jiaohui Tang ◽  
Bin Du

Under the background of vigorously promoting the high-quality economic development model in China, this paper proposes a Dynamic Double Index model to evaluate the fiscal output quality of cities in the Pearl River Delta. The empirical results show that Shenzhen, Guangzhou are at a high quality level, while Zhuhai, Foshan, Huizhou, Zhongshan and Dongguan are at a low quality level. This empirical result is consistent with the fact that Shenzhen has industrial tax source advantages, Guangzhou has consumption tax source advantages, but Zhuhai, Foshan, Huizhou Zhongshan and Dongguan do not have advantages. At the same time, the consistency also proves that the Dynamic Double Index model has accurate measurement function and can be used as a powerful tool to deal with big data information problems.


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