The temporal-spatial distribution and changes of dissolved oxygen in the Changjiang Estuary and its adjacent waters for the last 50 a

Lu, Wenjin; Xiang, Xianquan; Yang, Liyuan; Xu, Youpeng; Li, Xiao; Liu, Shuming

doi:10.1007/s13131-017-1063-6

Cited by 20 publications

(4 citation statements)

References 14 publications

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“…The annual average of water temperature is 17.55 °C, and the seasonal concentrations range from 6.12 °C (winter) to 27.78 °C (summer). Water temperature can affect the contents of DO, BOD 5 , and the vertical distribution of many inorganic salts [65], and can directly change the nitrogen and phosphorus cycle processes [6,62,63]. The relationships and interactions of water temperature and other water quality indicators need further study.…”

Section: Resultsmentioning

confidence: 99%

“…The BOD 5 indicates the degree of organic pollution in water body, i.e., the higher the BOD 5 concentrations, the more dissolved oxygen is consumed by microbial metabolism, hence the BOD 5 generally has a strong a negative correlation with dissolved oxygen (−0.829, P < 0.01) [52]. High temperature and sunshine duration in summer easily lead to the escape of dissolved oxygen in water [65], so the DO generally has a negative correlation with water temperature (−0.798, P < 0.01). Moreover, when the dissolved oxygen content was high, the sediment in water was at an oxidation state that would be suitable for the growth of aerobic bacteria such as nitrobacteria and nitrifying bacteria, and can accelerate the nitrogen and phosphorous cycle processes [62], resulting in the DO having a negative correlation with TN (−0.688, P < 0.01) and TP (−0.870, P < 0.01).…”

Section: Resultsmentioning

confidence: 99%

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Spatio-Temporal Characterization Analysis and Water Quality Assessment of the South-to-North Water Diversion Project of China

Nong

Shao

Xiao

et al. 2019

IJERPH

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In this article, a data matrix of 20 indicators (6960 observations) was obtained from 29 water quality monitoring stations of the Middle Route (MR) of the South-to-North Water Diversion Project of China (SNWDPC). Multivariate statistical techniques including analysis of variance (ANOVA), correlation analysis (CA), and principal component analysis (PCA) were applied to understand and identify the interrelationships between the different indicators and the most contributive sources of anthropogenic and natural impacts on water quality. The water quality index (WQI) was used to assess the classification and variation of water quality. The distributions of the indicators revealed that six heavy-metal indicators including arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), selenium (Se), and lead (Pb) were within the Class I standard, while the As, Pb, and Cd displayed spatial variation. Moreover, some physicochemical indicators such as dissolved oxygen, 5-day biochemical oxygen demand (as BOD5), and total phosphorus (TP) had spatio-temporal variability. The correlation analysis result demonstrated that As, Hg, Cd, Cr, Se, Pb, copper (Cu), and zinc (Zn) had high correlation coefficients. The PCA result extracted three principal components (PC) accounting for 82.67% of the total variance, while the first PC was indicative of the mixed sources of anthropogenic and natural contributions, the second and the third PCs were mainly controlled by human activities and natural sources, respectively. The calculation results of the WQI showed an excellent water quality of the MR of the SNWDPC where the values of the stations ranged from 10.49 to 17.93, while Hg was the key indicator to determine the WQI > 20 of six stations, which indicated that the Hg can be the main potential threat to water quality and human health in this project. The result suggests that special attention should be paid to the monitoring of Hg, and the investigation and supervision within the areas of high-density human activities in this project should be taken to control the impacts of urban and industrial production and risk sources on water quality.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Spatio-Temporal Characterization Analysis and Water Quality Assessment of the South-to-North Water Diversion Project of China

Nong

Shao

Xiao

et al. 2019

IJERPH

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“…In the coastal regions of China, hypoxia and acidification have occurred in the estuaries of large rivers such as the Changjiang River [8][9][10][11][12] and the Pearl River [13,14] since the late 1950s, while the Bohai Sea (Figure 1) has newly developed an oxygen deficit in the past 20 years. In 2012, the oxygen deficit in the Bohai Sea began to receive attention when it was first reported by Zhai et al [15].…”

Section: Introductionmentioning

confidence: 99%

A Three-Dimensional Spatial Interpolation Method and Its Application to the Analysis of Oxygen Deficit in the Bohai Sea in Summer

Zhao,

Guo,

Xiao

et al. 2024

JMSE

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Dissolved oxygen (DO) plays a pivotal role in sustaining marine ecosystems. The Bohai Sea in China is a semi-enclosed sea, and oxygen-deficit events occur from time to time due to human activities. At present, there is a notable absence of any convenient and precise method for obtaining three-dimensional spatial data on DO, and the exploration of the physical mechanisms influencing oxygen deficit remains incomplete. This investigation uses the linear radial basis function (RBF-Linear) fitting method to conduct three-dimensional spatial interpolation for DO, which demonstrates minimal inaccuracy. Then, the RBF-Linear fitting method is utilized to collect a comprehensive three-dimensional spatial dataset encompassing temperature, salinity, and DO in the Bohai Sea in August from 2016 to 2018. The results indicate discernible interannual variations in the extent, area, and distribution of oxygen deficiency during summer in the Bohai Sea. Mechanism analysis reveals that intense precipitation episodes and an increase in wind stress curl exacerbate oxygen depletion. Additionally, the degree, location, and area of the two oxygen-deficit cores (off the Yellow River Estuary and off the Qinhuangdao) in the Bohai Sea are influenced by several factors, including current velocity, direction, local circulation position, and net horizontal transport rate. Furthermore, the study suggests that oxygen deficiency in the Bohai Sea region is currently in its early stages, with a limited degree of injury and a restricted range of influence. The use of a three-dimensional spatial interpolation method to create a complete DO field in three-dimensional space simplifies the research challenges associated with marine oxygen deficit. Moreover, this study holds particular significance for guiding the development of marine fisheries.

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“…Since the late 1950s, hypoxia and seawater acidification have occurred in the estuaries of large rivers, such as the Changjiang River (Wei et al, 2007;Lu et al, 2017;Wei et al, 2017;Zhou et al, 2017;Luo et al, 2018) and the Pearl River (Su et al, 2017;Qian et al, 2018), in coastal China. There have been many studies and analyses on the spatial and temporal distribution, variation and formation mechanism of hypoxia in these regions.…”

mentioning

confidence: 99%

Oxygen Deficit Area Spatial-temporal Heterogeneity in Bohai Sea: Formation and their Drivers

Zhao

Xiao

Guo

et al. 2022

Preprint

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In recent years, oxygen deficit in coastal seas has seriously affected the marine ecological environment. Using a large number of observed data in May and August from 2015 to 2018, we obtain the vertical distribution of DO and related hydrological factors in the central section of the Bohai Sea by three-dimensional spatial interpolation to analyze the variation characteristics and its potential changing drivers. The results show that there are two typical oxygen deficit regions in the bottom water of the central Bohai Sea in summer, which are located off Qinhuangdao (QHD) and off the Yellow River estuary (YRE). We analyze the main mechanisms for the formation of oxygen deficit regions: continuous strong stratification and high temperature in summer as well as the aerobic decomposition of organic matter produced after the death of the massive phytoplankton in spring and summer during the slow sedimentation process. In addition, the physical-biological mechanisms of QHD and YRE, the two oxygen deficit core regions, are obviously different. This comparison highlights the influence of the initiation time of stratification enhancement and phytoplankton species on the degree of oxygen deficit, which provides a new understanding for perfecting the formation mechanism of oxygen deficit. Finally, two oxygen deficit regions are simply predicted, which highlights the seriousness of oxygen deficit in Bohai Sea.

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The temporal-spatial distribution and changes of dissolved oxygen in the Changjiang Estuary and its adjacent waters for the last 50 a

Cited by 20 publications

References 14 publications

Spatio-Temporal Characterization Analysis and Water Quality Assessment of the South-to-North Water Diversion Project of China

Spatio-Temporal Characterization Analysis and Water Quality Assessment of the South-to-North Water Diversion Project of China

A Three-Dimensional Spatial Interpolation Method and Its Application to the Analysis of Oxygen Deficit in the Bohai Sea in Summer

Oxygen Deficit Area Spatial-temporal Heterogeneity in Bohai Sea: Formation and their Drivers

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