scholarly journals Vertical variations in optical properties of the waters in the Yellow Sea and Bohai Sea at seasonal scales and their influencing mechanisms

2018 ◽  
Vol 26 (4) ◽  
pp. 4112 ◽  
Author(s):  
Shuguo Chen ◽  
Tinglu Zhang ◽  
Lianbo Hu ◽  
Cheng Xue ◽  
Xiao Wu
2019 ◽  
Vol 11 (10) ◽  
pp. 1187 ◽  
Author(s):  
Qiong Tang ◽  
Shengqiang Wang ◽  
Zhongfeng Qiu ◽  
Deyong Sun ◽  
Muhammad Bilal

A cross-sectional area (CSA) is a key element in the optical properties of suspended particles. The seasonal evolution of CSA has great potential for use in mapping total suspended particles, and such mapping plays an important role in water quality monitoring. In this study, the spatiotemporal variations in CSA in the Bohai Sea and the Yellow Sea were studied using temperature, salinity and chlorophyll-a data collected by four cruises. The CSA field data covered a wide range of spatiotemporal variabilities in the Bohai Sea and the Yellow Sea. The results revealed that the largest CSA (>2 m−1) was found in the coastal area, while the CSA (≤1 m−1) on the outer shelf was much smaller. Large values of CSA (>15 m−1) were observed in winter, whereas the smallest values of CSA (0~2 m−1) were observed in summer. These results suggest that vertical mixing and ocean stratification might be important physical mechanisms that influences the CSA seasonal distribution in the surface layer. The results also showed that phytoplankton played an important role in the CSA, with an R2 value of 0.601. The seasonal patterns of CSA documented in this study provide a fundamental theory for research on optical properties, mapping transparency, and photosynthetically active radiation.


2019 ◽  
Vol 16 (22) ◽  
pp. 4485-4496 ◽  
Author(s):  
Ye Tian ◽  
Chao Xue ◽  
Chun-Ying Liu ◽  
Gui-Peng Yang ◽  
Pei-Feng Li ◽  
...  

Abstract. Nitric oxide (NO) is a short-lived compound of the marine nitrogen cycle; however, our knowledge about its oceanic distribution and turnover is rudimentary. Here we present the measurements of dissolved NO in the surface and bottom layers at 75 stations in the Bohai Sea (BS) and the Yellow Sea (YS) in June 2011. Moreover, NO photoproduction rates were determined at 27 stations in both seas. The NO concentrations in the surface and bottom layers were highly variable and ranged from below the limit of detection (i.e., 32 pmol L−1) to 616 pmol L−1 in the surface layer and 482 pmol L−1 in the bottom layer. There was no significant difference (p>0.05) between the mean NO concentrations in the surface (186±108 pmol L−1) and bottom (174±123 pmol L−1) layers. A decreasing trend of NO in bottom-layer concentrations with salinity indicates a NO input by submarine groundwater discharge. NO in the surface layer was supersaturated at all stations during both day and night and therefore the BS and YS were a persistent source of NO to the atmosphere at the time of our measurements. The average flux was about 4.5×10-16 mol cm−2 s−1 and the flux showed significant positive relationship with the wind speed. The accumulation of NO during daytime was a result of photochemical production, and photoproduction rates were correlated to illuminance. The persistent nighttime NO supersaturation pointed to an unidentified NO dark production. NO sea-to-air flux densities were much lower than the NO photoproduction rates. Therefore, we conclude that the bulk of the NO produced in the mixed layer was rapidly consumed before its release to the atmosphere.


2019 ◽  
Vol 58 (4) ◽  
pp. 903-917 ◽  
Author(s):  
Manman Ma ◽  
Yu Zhen ◽  
Tiezhu Mi

AbstractStudies of the community structures of bacteria in marine aerosols of different particle sizes have not been reported. Aerosol samples were collected using a six-stage bioaerosol sampler over the Bohai Sea, the Yellow Sea, and northwestern Pacific Ocean in the spring of 2014. The diversity and composition of these samples were investigated by Illumina high-throughput sequencing, and 130 genera were detected in all of the samples; the most abundant bacterial genus was Bacteroides, followed by Prevotella and Megamonas. The Chao1 and Shannon diversity indices ranged from 193 to 1044 and from 5.44 to 8.33, respectively. The bacterial community structure in coarse particles (diameter larger than 2.1 μm) was more complex and diverse than that in fine particles (diameter less than 2.1 μm) in marine bioaerosols from over the Yellow Sea and northwestern Pacific Ocean, while the opposite trend was observed for samples collected over the Bohai Sea. Although we were sampling over marine regions, the sources of the bioaerosols were mostly continental. Temperature and wind speed significantly influenced the bacterial communities in marine aerosols of different particle sizes. There may be a bacterial background in the atmosphere in the form of several dominant taxa, and the bacterial communities are likely mixed constantly during transmission.


2016 ◽  
Author(s):  
Jun Liu ◽  
Lex Bouwman ◽  
Jiaye Zang ◽  
Chenying Zhao ◽  
Xiaochen Liu ◽  
...  

Abstract. Silicon (Si) and carbon (C) play key roles in the river and marine biogeochemistry. The Si and C budgets for the Bohai Sea were established on the basis of measurements at a range of stations and additional data from the literature. The results show that the spatial distributions of reactive Si and organic C (OC) in the water column are largely affected by the riverine input, primary production and export to the Yellow Sea. Biogenic silica (BSi) and total OC in sediments are mainly from marine primary production. The major supply of dissolved silicate (DSi) comes from benthic diffusion, riverine input alone accounts for 17 % of reactive Si inputs to the Bohai Sea; the dominant DSi removal from the water column is diatom uptake, followed by sedimentation. Rivers contribute 47 % of exogenous OC inputs to the Bohai Sea; the dominant outputs of OC are sedimentation and export to the Yellow Sea. The net burial of BSi and OC represent 3.3 % and 1.0 % of total primary production, respectively. Primary production has increased by 10 % since 2002 as a result of increased river loads of DSi and BSi. Our findings underline the critical role of riverine Si supply in primary production in coastal marine ecosystems.


2022 ◽  
Vol 294 ◽  
pp. 118640
Author(s):  
Mingyu Zhang ◽  
Yan Lin ◽  
Andy M. Booth ◽  
Xikun Song ◽  
Yaozong Cui ◽  
...  

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