Spatial distribution and behavior of dissolved selenium speciation in the South China Sea and Malacca Straits during spring inter-monsoon period

Selenium(Se)has been recognized as a key trace element that is associated with growth of primary producers in oceans.During March and May 2018,surface water(67 samples)was collected and measured by HG-ICP-MS to investigate the distribution and behavior of selenite[Se(Ⅳ)],selenate[Se(Ⅵ)]and dissolved organic selenides(DOSe)concentrations in the Zhujiang River Estuary(ZRE),South China Sea(SCS)and Malacca Straits(MS).It showed that Se(Ⅳ)(0.14–3.44 nmol/L)was the dominant chemical species in the ZRE,related to intensive manufacture in the watershed;while the major species shifted to DOSe(0.05–0.79 nmol/L)in the MS,associated with the wide coverage of peatland and intensive agriculture activities in the Malaysian Peninsula.The SCS was identified as the northern and southern sections(NSCS and SSCS)based on the variations of surface circulation.The insignificant variation of Se(IV)in the NSCS and SSCS was obtained in March,potentially resulting from the high chemical activity and related preferential assimilation by phytoplankton communities.Contrastively,the lower DOSe concentrations in the SSCS likely resulted from higher primary production and utilization during March.During May,the concentration of Se(Ⅳ)remained low in the NSCS and SSCS,while DOSe concentrations increased notably in the SSCS,likely due to the impact of terrestrial inputs from surface current reversal and subsequent accumulation.On a global scale,DOSe is the dominant Se species in tropical oceans,while Se(Ⅳ)and Se(Ⅵ)are major fractions in high-latitude oceans,resulting from changes in predominated phytoplankton and related biological assimilation.

Nitrate in the Changjiang diluted water:an isotopic evaluation on sources and reaction pathways

A cruise covering two transects in the Changjiang(Yangtze)estuary in July 2017 was conducted,aiming to explore the sources for riverine NOˉ3 and identify reactions involved in the NO_(3)^(-)transformations along the transport of the Changjiang diluted water(CDW).In the river water,NO_(3)^(-)was fundamentally contributed by chemical fertilizer leakage in the watershed according to isotope signals.Sewage discharge may also be significant on riverine NO_(3)^(-)inventory,while the isotope signal was masked by nitrification.Together with the transport of the CDW,NO_(3)^(-)production was observed in waters with low salinities(<20)and high turbidities.Nitrification resulted from the mineralization of riverine organic nitrogen;therefore,the high turbidity was linked to active production.In the outer plume,coupled with stratification,a significant decrease in NO_(3)^(-)concentration was observed in the surface water.In parallel,enrichment inδ^(15)N-NO_(3)^(-)andδ^(18)O-NO_(3)^(-)was found,indicating biological consumption by phytoplankton.The difference in the stratification intensity between two transects led to variations in NO_(3)^(-)concentrations and isotope compositions.In the benthic water,denitrification(sediment-water interface)and nitrification(bottom water)coexisted.Furthermore,accumulations of NH4+and dissolved organic nitrogen in the bottom water were observed,indicating that nitrification was constrained by oxidant(mainly dissolved oxygen)supplies.

Sandy seepage faces as bioactive nitrate reactors:Biogeochemistry,microbial ecology and metagenomics

Subterranean estuaries are highly dynamic in processing dissolved inorganic nitrogen(DIN).Here we investigate DIN turnover in surface sediments(0–20 cm depth)at the higher,medium and lower intertidal of a seepage face,i.e.,the outer “mouth”of the subterranean estuary,during four consecutive seasons in Sanggou Bay,China.Throughout the studied period,ammonium(NH_(4)^(+))and nitrite(NO_(2)^(-))concentrations in the sampled porewaters did not vary significantly with depth or season.In contrast,peaks in porewater nitrate(NO_(3)^(-))concentration and decreases in δ^(15)N-NO_(3)^(-) and δ^(18)O-NO_(3)^(-) were observed in the 15–20 cm depth(bottom)sediment,particularly during summer and autumn.Coupled with NO_(3)^(-) production,the sediment total nitrogen was also markedly peaking in the bottom layer of the studied seepage face.Together with abundant heterotrophic microbes in the sediment,this NO_(3)^(-) accumulation was linked to a reaction chain including organic matter decomposition,ammonification and nitrification.During winter,porewater enrichment in total nitrogen occurred closer to the surface of the seepage face but triggered also active NO_(3)^(-) production.This pattern reinforced the importance of pelagic organic matter supply on NO_(3)^(-) production.In the shallower depths of the seepage face(<12 cm),active net NO3removal occurred except in winter.The isotopic fractionation(δ^(15)N-NO_(3)^(-) and δ^(18)O-NO_(3)^(-) and metagenomic results revealed denitrification as the main pathway for NO_(3)^(-) reduction.Biological assimilation from benthic primary producers may also consume a fraction of NO_(3)^(-) at the sediment water interface.Both NO_(3)^(-) production and removal significantly varied in magnitude with season(13.6 to 6.2 nmol cm^(-3)h^(-1)).Substrate supply was the key driver for nitrate cycling,as evidenced by the high NO3production rate in spring by comparison to autumn.The highest NO_(3)^(-) turnover rates were found in summer,suggesting the combined influence of advection rates and sediment microbiota composition.In spite of active removal(peak NO_(3)^(-) removal capability:61%),a significant amount of NO_(3)^(-) was still transported from the seepage face into the bay waters.The magnitude of NO_(3)^(-) fluxes ranged from 312 to 476 kg N d^(-1),accounting for approximately 15%of the total exogenous NO_(3)^(-) loading into the bay.NO_(3)^(-) isotopic fingerprint revealed chemical fertilizer as the main source of terrestrial NO_(3)^(-) in SGD,highlighting the importance of land use to coastal system nitrogen budgets.

OShnscc:a novel user-friendly online survival analysis tool for head and neck squamous cell carcinoma based on RNA expression profiles and long-term survival information

Head and neck squamous cell carcinoma(HNSCC),as the most common type(>90%)of head and neck cancer,includes various epithelial malignancies that arise in the nasal cavity,oral cavity,pharynx,and larynx.In 2020,approximately 878000 new cases and 444000 deaths linked to HNSCC occurred worldwide(Sung et al.,2021).Due to the associated frequent recurrence and metastasis.

From the water sources of the Tibetan Plateau to the ocean:State of nutrients in the Changjiang linked to land use changes and climate variability

Anthropogenic activity is an important driver of changes in the chemistry of nutrients(N,P,and Si)over watersheds at the sub-continental scale(e.g.,106km~2)and can markedly modify their seaward fluxes to the global ocean.In the present study,we reviewed the current status of nutrient chemistry in Changjiang(Yangtze River)based on data collected through 11 expeditions along a river course spanning 4,500 km and 15–20 major tributaries during 1997–2016 as well as monthly monitoring at the river mouth since 1980.The data were analyzed together with published results in the literature to synthesize the recent developments and current state of nutrients in the Changjiang.Previously published results from the Qinghai-Tibetan Plateau head waters were included to realize the systematics of nutrients for the whole drainage basin.Here,we showed that tributaries of the upper reaches of watersheds collectively determine the regime with high concentration and skewed species ratio of nutrients in the Changjiang mainstream,producing profound effects over a water course of 2,000–2,500 km further downstream and until the river mouth.Moreover,using data across the Three Gorges Reservoir(TGR)during 2003–2016,we evaluated the trapping and/or amplifying effects of the Three Gorges Dam(TGD)on nutrient chemistry.Tide-influenced river delta contributed an additional 20%dissolved inorganic phosphorus and 5–10%dissolved inorganic nitrogen and dissolved silicates to the seaward flux,dramatically affecting the stoichiometry of nutrients at the river mouth.Next,based on compiled data on supply and export,legacy nutrients were evaluated.Both nitrogen and phosphorus are in the accumulation phase over the watersheds,and the legacy nutrient fluxes are much higher than the annual riverine seaward fluxes.Finally,we demonstrated that the seaward fluxes of anthropogenic nutrients from the Changjiang exceed those from other top 10 largest rivers on this planet,which can be attributed to land use changes in the China over the last three to four decades.