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| 1 | Using Natural Radionuclides to Trace Sources of Suspended Particles in the Lower Reaches of the Yellow River显示文摘Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and desorption.We analyzed the activi-ties and distribution characteristics of multiple natural radionuclides(238U,226Ra,40K,228Ra,7Be and 210Pbex)on size-fractionated SPM at the Lijin Hydrographic Station(Huanghe or Yellow River)every month over a one-year period.Results showed that medium silt(16–32µm)was the main component.As expected,the activity of each radionuclide decreased with an increase of particle size.We examined the sources of SPM with different particle sizes using activity ratios of 226Ra/238U,228Ra/226Ra,40K/238U and 7Be/210Pbex,and concluded that SPM with different particle sizes originated from different sources.Our results indicate that fine SPM(<32µm)was mainly from the erosion of soil along the lower reaches of the Yellow River,while coarse SPM(>32µm)was mainly derived from resuspension of riverbed sediment.During high runoff periods,the concentration of SPM increased significantly,and the pro-portion of fine particles originating upstream increased.Naturally occurring radioactive isotopes,especially on size-fractionated par-ticles,are therefore seen as useful tracers to understand the sources and behaviors of riverine particles transported from land to sea. | ZHANG Han BURNETT CWilliam ZHANG Xiaojie ZHAO Shibin YANG Disong NAN Haiming YU Zhigang XU Bochao | 2024 | Journal of Ocean University of China2024，23，1： | 0 |
| 2 | Using Rn-222 to Study Human-Regulated River Water-Sediment Input Event in the Estuary显示文摘The implementation of the water sediment regulation scheme(WSRS)is a typical example of artificially controlling land-source input.During WSRS,the water discharge of the Yellow River will increase significantly,and so will the input of terri-genous materials.In this study,we used a natural geochemical tracer 222Rn to quantify terrestrial inputs under the influence of the 2014 WSRS in the Yellow River Estuary.The results indicated that during WSRS the concentration of 222Rn in the estuary increased by about four times than in the period before WSRS.The high-level 222Rn plume disappeared quickly after WSRS,indicating that 222Rn has a very short‘memory effect’in the estuary.Based on the investigation conducted from 2015 to 2016,the concentration of 222Rn tended to be stable in the lower reaches of the Yellow River.During WSRS,the concentrations of 222Rn in the river water in-creased sharply at about 3–5 times greater than in the non-WSRS period.Based on the 222Rn mass balance model,the fluxes of 222Rn caused by submarine groundwater discharge(SGD)were estimated to be(3.5±1.7)×10^(3),(11±3.9)×10^(3),and(5.2±1.9)×10^(3)dpm m^(-2)d^(-1)in the periods before,during,and after WSRS,respectively.This finding indicated that SGD was the major source of 222Rn in the Yellow River Estuary,which can be significantly increased during WSRS.Furthermore,the SGD-associated nutrient fluxes were estimated to be 9.8×10^(3),2.5×102,and 1.1×10^(4)μmolm^(-2)d^(-1)for dissolved inorganic nitrogen,phosphorus,and silicon,respectively,during WSRS or about 2–40 times greater than during the non-WSRS period. | XU Yuezhi XIAO Liu GAO Maosheng YANG Disong ZHAO Shibin XU Haowei WANG Lisha ZHANG Xiaojie | 2023 | Journal of Ocean University of China2023，22，6： | 0 |
| 3 | Using radium isotopes to quantify submarine groundwater discharge at different scales in the Huanghe River Estuary,China显示文摘As an important land-ocean interaction process,submarine groundwater discharge(SGD)is composed of multiple dynamical processes at different scales and plays an important role in the study of coastal ocean geochemical budgets.However,most of the existing studies focus on the quantification of the total groundwater discharge,few studies are about the differentiation and quantification of groundwater discharge processes at different scales(i.e.,short-scale SGD and long-scale SGD).As a world-class river,the Huanghe River is highly turbid and heavily regulated by humans.These natural and anthropogenic factors have a significant impact on groundwater discharge processes in the Huanghe River Estuary(HRE).In this study,the distribution patterns of the natural geochemical tracer radium isotopes(^(224)Ra and^(223)Ra)and other hydrological parameters in the HRE were investigated during four cruises.By solving the mass balance of^(224)Ra and^(223)Ra in the HRE,the long-scale SGD flux was quantified as 0.01−0.19 m/d,and the short-scale SGD flux was 0.03−0.04 m/d.The rate of short-scale SGD remained essentially constant among seasons,while the rate of long-scale SGD varied considerably at different periods and showed a synchronous trend with the variation of river discharge.The results of this study are significant for understanding the SGD dynamics in the HRE and the contribution of SGD to the ocean geochemical budgets. | Haowei Xu Disong Yang Xiaoyi Guo Maosheng Gao Guangquan Chen Diansheng Ji Shengtao Chen Huaming Yu Bochao Xu | 2023 | Acta Oceanologica Sinica2023，42，8： | 0 |
| 4 | Submarine groundwater discharge and benthic biogeochemical zonation in the Huanghe River Estuary显示文摘Submarine groundwater discharge(SGD)has received increasing attention by studies on coastal areas;however,its effects on biogeochemical zonation have not been investigated to date.The Huanghe River Estuary(HRE)is a world class river estuary with high turbidity,and heavy human regulation.This study investigated how SGD is related to the benthic biogeochemistry of the HRE.Based on the distribution of several parameters(e.g.,salinity,temperature,dissolved oxygen(DO)levels,p H,radium isotopes,and nutrients),the HRE was subdivided into six different zones,and the SGD fluxes within each zone were quantified and compared.The highest SGD flux was found in the northwest nearshore zone,where it was more than one order of magnitude higher than in the offshore zone.High SGD resulted in low DO and p H,but high nutrient levels in the benthic boundary layer.The southeast nearshore zone was also characterized by high SGD flux,but benthic waters were more oxic because of the dominating inputs by the Huanghe River.These data suggest that such a zonation would help to understand benthic biogeochemical processes.High SGD may not only contribute to the estuarine nutrient budget,but may also contribute to the formation of hypoxia and acidification. | Guangquan Chen Bochao Xu Shibin Zhao Disong Yang William C.Burnett Shaobo Diao Maosheng Gao Xingyong Xu Lisha Wang | 2022 | Acta Oceanologica Sinica2022，41，1： | 0 |
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