Concentrations and distribution of transparent exopolymer particles in a eutrophic coastal sea: a case study of the Changjiang (Yangtze River) estuary

2019 ◽  
Vol 70 (10) ◽  
pp. 1389 ◽  
Author(s):  
Shujin Guo ◽  
Xiaoxia Sun
Keyword(s):  
Yangtze River ◽  
Significant Positive Correlation ◽  
River Estuary ◽  
Bottom Layer ◽  
Distribution Patterns ◽  
Carbon Pool ◽  
Yangtze River Estuary ◽  
Transparent Exopolymer Particles ◽  
Positive Correlation ◽  
P Limitation

Transparent exopolymer particles (TEPs) contribute to carbon export and can represent a significant part of the carbon pool, most notably in eutrophic systems. This study represents the first investigation of the concentrations and distribution of TEPs in the Changjiang (Yangtze River) estuary, one of the most eutrophic coastal seas in the world. The concentration of TEPs was determined on a seasonal basis (spring, summer and autumn), and the distribution patterns of TEPs were studied with respect to physical, chemical and biological conditions. Spatially, TEP concentrations exhibited a significant positive correlation with chlorophyll-a concentrations in spring and summer, which implies a consistent production of TEPs by phytoplankton cells. Vertically, TEP concentrations decreased gradually from the surface layer to the bottom layer in spring and summer, but were distributed homogenously in the water column in autumn. Values of nitrogen:phosphorus ratio (N:P) were found to have a significant positive correlation with TEP concentrations in summer, indicating that a P limitation would probably accelerate production and formation of TEPs. TEP-carbon (TEP-C) concentration was found to be similar to phytoplankton-C in the study area, highlighting the fact that TEP-C could represent a significant fraction of the particulate organic carbon pool in the Changjiang (Yangtze River) estuary.

scholarly journals Sinking rates and export flux of Transparent Exopolymer Particles (TEPs) in an eutrophic coastal sea: a case study in the Changjiang (Yangtze River) Estuary

2018 ◽  
Author(s):  
Shujin Guo ◽  
Jun Sun
Keyword(s):  
Significant Role ◽  
Yangtze River ◽  
Significant Positive Correlation ◽  
Carbon Sink ◽  
River Estuary ◽  
Yangtze River Estuary ◽  
Transparent Exopolymer Particles ◽  
Export Flux ◽  
Coastal Sea

AbstractTransparent exopolymer particles (TEPs) are ubiquitous throughout the oceans, and their sedimentation is considered an efficient biological carbon sink pathway. However, the role TEPs play as a carbon sink in eutrophic coastal seas is not well studied. In order to investigate this issue, two cruises in the spring and summer of 2011 were carried out in the Changjiang (Yangtze River) estuary, a typical eutrophic coastal sea. The concentrations, sinking rates, and export flux of TEPs were studied. TEP concentrations ranged from 40.00 to 1040.00 μg Xeq L−1 (mean = 209.70 ± 240.93 μg Xeq L−1) in spring and from 56.67 to 1423.33 μg Xeq L−1 (mean = 433.33 ± 393.02 μg Xeq L−1) in summer. A significant positive correlation between TEP concentrations and chlorophyll (Chl) a concentrations was observed. TEP sinking rates ranged from 0.08 to 0.57 m d−1 (mean = 0.28 ± 0.14 m d−1) in spring and from 0.10 to 1.08 m d−1 (mean = 0.34 ± 0.31 m d−1) in summer. TEP sinking rates were always higher in the upper layers than in the deeper layers during both seasons. The export flux of TEPs was also calculated, and it ranged from 4.95 to 29.40 mg C m−2 d−1 in spring (mean = 14.66 ± 8.83 mg C m−2 d−1) and from 6.80 to 30.45 mg C m−2 d−1 (mean = 15.71 ± 8.73 mg C m−2 d−1) in summer. This study is the first study on TEP sinking in the Changjiang (Yangtze River) Estuary, and it confirmed that TEP plays a significant role as a carbon sink in the eutrophic coastal sea.

scholarly journals Summer distribution patterns of Trichodesmium spp. in the Changjiang (Yangtze River) Estuary and adjacent East China Sea shelf

Oceanologia ◽  
2017 ◽  
Vol 59 (3) ◽  
pp. 248-261 ◽  
Author(s):  
Zhibing Jiang ◽  
Jianfang Chen ◽  
Feng Zhou ◽  
Hongchang Zhai ◽  
Dongsheng Zhang ◽  
...  
Keyword(s):  
East China Sea ◽  
Yangtze River ◽  
River Estuary ◽  
Distribution Patterns ◽  
East China ◽  
Yangtze River Estuary ◽  
China Sea ◽  
East China Sea Shelf ◽  
Summer Distribution

The Temporal and Spatial Variation of the Nutrientsin the Yangtze River Estuary

2014 ◽  
Vol 1010-1012 ◽  
pp. 399-402
Author(s):  
Hao Liu ◽  
Wen Shan Xu ◽  
Hong Xuan Kang ◽  
Bao Shu Yin
Keyword(s):  
Spatial Variation ◽  
Yangtze River ◽  
River Estuary ◽  
Bottom Layer ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
Temporal And Spatial Variation ◽  
The Yangtze River Estuary ◽  
Temporal And Spatial ◽  
High Level

This paper mainly focuses on the temporal and spatial variation of nutrients in the Yangtze River Estuary. Observations show that the high level of nitrate concentration appears in the coast waters and gradually decreases toward the continental shelf both in summer and in winter; while the ammonium and phosphate concentrations show the relatively high level in the bottom layer of the water column in summer, since ammonium and phosphate can be regenerated on the sediments and reenter the bottom layer of the water column to make up their contents. In winter, the nutrients are well-distributed in the vertical due to the strong mixing mechanism. The further examination of the nutrient limitation, according to the Redfield theory, shows that the phosphorus limitation dominates in the river mouth and then shift to the nitrogen limitation toward the continental shelf gradually. The variation of the nutrient limitation may be dependent on the relative strength between the Changjiang Diluted Water and the Intrusion Branch of the Kuroshio Current.

Natural and anthropogenic forcing on the dynamics of virioplankton in the Yangtze river estuary

2006 ◽  
Vol 86 (3) ◽  
pp. 543-550 ◽  
Author(s):  
Nianzhi Jiao ◽  
Yanlin Zhao ◽  
Tingwei Luo ◽  
Xiulin Wang
Keyword(s):  
Yangtze River ◽  
Anthropogenic Impacts ◽  
River Estuary ◽  
Distribution Patterns ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
Viral Abundance ◽  
Estuarine Area ◽  
Algal Virus ◽  
River Estuarine

Seasonal investigation of virus dynamics by flow cytometry was conducted in the Yangtze river estuarine area in April, August, November 2002 and February 2003, and a supplemental investigation in the inner estuary and downstream of the river was conducted in October 2005. The majority of the total viral abundance was bacteriophage and only 5.4% of the total was algal virus. Total viral abundance varied with season and location, ranging from 6.75×105–1.68×107 particles/ml, and the virus:bacterium ratio (VBR) ranged from 1.52 to 72.02 with a mean of 8.7. In the present study, viral abundance peaked in both the summer and the winter, unlike the typical seasonal pattern reported in the literature, in which viral abundance peaks in the summer when bacterial hosts are also at their most abundant. However, the driving forces for the two peaks reported here were totally different, the summer viral abundance peak coupled with the development of bacterial hosts which were controlled largely by temperature year-round and by trophic state occasionally, while the winter one seemed to be multi-factor controlled. The host-phage interaction was no longer predominant in control of the winter viral abundance as bacterial abundance was lowest in this season. The winter low temperature would help maintain a high viral abundance as high temperatures might increase viral inactivation and viral decay; the VBR peak values actually occurred in the winter. More importantly, the high virus-containing freshwater discharge in winter due to a higher proportion of anthropogenic sewage relative to low natural flooding in winter run-off, turned out to be the first factor contributing to the high winter viral abundance and VBR values. In addition, the variation of intrusion of warm and relatively oligotrophic water from oceanic currents played a role alternating the distribution patterns of temperature, salinity and trophic conditions and consequently the distribution patterns of virus and bacteria seasonally and spatially. Dynamics of virus in the Yangtze river estuarine area is thus characterized by distinct seasonal and spatial variations due to natural forcing and by pronounced alternation of the regular patterns due to anthropogenic impacts.

scholarly journals Spatial and Temporal Variability of Soil Salinity in the Yangtze River Estuary Using Electromagnetic Induction

2021 ◽  
Vol 13 (10) ◽  
pp. 1875
Author(s):  
Wenping Xie ◽  
Jingsong Yang ◽  
Rongjiang Yao ◽  
Xiangping Wang
Keyword(s):  
Electrical Conductivity ◽  
Spatial Distribution ◽  
Soil Salinity ◽  
Yangtze River ◽  
Laboratory Data ◽  
River Estuary ◽  
Yangtze River Estuary ◽  
Soil Electrical Conductivity ◽  
The Yangtze River ◽  
The Yangtze River Estuary

Soil salt-water dynamics in the Yangtze River Estuary (YRE) is complex and soil salinity is an obstacle to regional agricultural production and the ecological environment in the YRE. Runoff into the sea is reduced during the impoundment period as the result of the water-storing process of the Three Gorges Reservoir (TGR) in the upper reaches of the Yangtze River, which causes serious seawater intrusion. Soil salinity is a problem due to shallow and saline groundwater under serious seawater intrusion in the YRE. In this research, we focused on the temporal variation and spatial distribution characteristics of soil salinity in the YRE using geostatistics combined with proximally sensed information obtained by an electromagnetic induction (EM) survey method in typical years under the impoundment of the TGR. The EM survey with proximal sensing method was applied to perform soil salinity survey in field in the Yangtze River Estuary, allowing quick determination and quantitative assessment of spatial and temporal variation of soil salinity from 2006 to 2017. We developed regional soil salinity survey and mapping by coupling limited laboratory data with proximal sensed data obtained from EM. We interpreted the soil electrical conductivity by constructing a linear model between the apparent electrical conductivity data measured by an EM 38 device and the soil electrical conductivity (EC) of soil samples measured in laboratory. Then, soil electrical conductivity was converted to soil salt content (soil salinity g kg−1) through established linear regression model based on the laboratory data of soil salinity and soil EC. Semivariograms of regional soil salinity in the survey years were fitted and ordinary kriging interpolation was applied in interpolation and mapping of regional soil salinity. The cross-validation results showed that the prediction results were acceptable. The soil salinity distribution under different survey years was presented and the area of salt affected soil was calculated using geostatistics method. The results of spatial distribution of soil salinity showed that soil salinity near the riverbanks and coastlines was higher than that of inland. The spatial distribution of groundwater depth and salinity revealed that shallow groundwater and high groundwater salinity influenced the spatial distribution characteristics of soil salinity. Under long-term impoundment of the Three Gorges Reservoir, the variation of soil salinity in different hydrological years was analyzed. Results showed that the area affected by soil salinity gradually increased in different hydrological year types under the impoundment of the TGR.

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