The geogenic enrichment of arsenic(As)extensively occurred in the riverine systems from the Qinghai-Tibetan Plateau under active geothermal discharge and chemical weathering conditions,while little is known about how ...The geogenic enrichment of arsenic(As)extensively occurred in the riverine systems from the Qinghai-Tibetan Plateau under active geothermal discharge and chemical weathering conditions,while little is known about how dissolved organic matter(DOM)transformation regulates the aquatic As concentrations.The present study revealed that the DOM components from the Singe Tsangpo River(STR)basin primarily consisted of protein-like components(81.30%±6.48%),with the microbially-endogenous production being a predominant source under the control of temperature and glacier-runoff recharge along the river flow path.Notably,the chemical weathering processes have significantly facilitated the enhancement of humic-like components in the river water.Besides,the groundwater DOM characteristics were predominantly influenced by the mobilization of sedimentary organic matter and the introduction of allochthonous DOM resulting from surface-water recharge.Interestingly,humic-like components facilitated As enrichment through complexation and competitive adsorption effects in both surface water and groundwater under oxidizing conditions,whichwas supported by the significant positive correlations between As and humiclike component(R^(2)=0.31/0.65,P<0.05/0.01)and the concurrent mobilization of As and humic-like components from sediment incubation experiments.Moreover,the Structural Equation Modeling analysis revealed a stronger contribution of humic-like components to the As enrichment in the groundwater compared with surface water,possibly due to the relatively strongermicrobial activity and enhanced mobilization of humic-like components in alluvial aquifers.The present study thus provided new insights into the transformation of DOM and its important role in facilitating As enrichment in the aquatic environment from alpine river basins.展开更多
The biogeochemical cycling on the Qinghai–Xizang Plateau is sensitive to climate change.Yet the response of fluvial nitrate(NO_(3)^(−))dynamics to climatic conditions on the plateau is poorly understood.Here,natural ...The biogeochemical cycling on the Qinghai–Xizang Plateau is sensitive to climate change.Yet the response of fluvial nitrate(NO_(3)^(−))dynamics to climatic conditions on the plateau is poorly understood.Here,natural abundance isotopes were synthesized and^(15)N pairing experiments were carried out to systematically clarify the drivers of NO_(3)^(−)-N levels in an alpine river on the southeastern Qinghai–Xizang Plateau in winter.The natural abundance isotopes(δ^(15)N/δ^(18)O_(NO3))of the river waters suggested that soil organic nitrogen(SON)was the primary source of riverine NO_(3)^(−)-N(96.5%±2.2%),and substantial biological NO_(3)^(−)removal occurred in the catchment.The ^(15)N pairing techniques quantified that the removal of NO_(3)^(−)in soils and river sediments,i.e.,dissimilatory NO_(3)^(−)reduction to ammonium(DNRA)denitrification,and anammox,was prevalent,which outcompeted nitrification.As SON dominated the NO_(3)^(−)sources,we focused on the drivers of NO_(3)^(−)production-related processes in the soils.The denitrification rates in the soils were largely controlled by moisture.展开更多
基金supported by the National Natural Science Foundation of China(No.42107094)Sichuan Science and Technology Program(No.2023NSFSC0806)the Geology Bureau project of Xinjiang Uygur Autonomous Region(Nos.XGMB202356 and XGMB202358).
文摘The geogenic enrichment of arsenic(As)extensively occurred in the riverine systems from the Qinghai-Tibetan Plateau under active geothermal discharge and chemical weathering conditions,while little is known about how dissolved organic matter(DOM)transformation regulates the aquatic As concentrations.The present study revealed that the DOM components from the Singe Tsangpo River(STR)basin primarily consisted of protein-like components(81.30%±6.48%),with the microbially-endogenous production being a predominant source under the control of temperature and glacier-runoff recharge along the river flow path.Notably,the chemical weathering processes have significantly facilitated the enhancement of humic-like components in the river water.Besides,the groundwater DOM characteristics were predominantly influenced by the mobilization of sedimentary organic matter and the introduction of allochthonous DOM resulting from surface-water recharge.Interestingly,humic-like components facilitated As enrichment through complexation and competitive adsorption effects in both surface water and groundwater under oxidizing conditions,whichwas supported by the significant positive correlations between As and humiclike component(R^(2)=0.31/0.65,P<0.05/0.01)and the concurrent mobilization of As and humic-like components from sediment incubation experiments.Moreover,the Structural Equation Modeling analysis revealed a stronger contribution of humic-like components to the As enrichment in the groundwater compared with surface water,possibly due to the relatively strongermicrobial activity and enhanced mobilization of humic-like components in alluvial aquifers.The present study thus provided new insights into the transformation of DOM and its important role in facilitating As enrichment in the aquatic environment from alpine river basins.
基金supported by the Natural Science Foundation of China(U23A2048)the Shenzhen Science and Technology Program(JCYJ20220531103015035)+2 种基金the Key R&D Program of Guangxi(GUIKE AB24010128)the Special Program of Key Sectors in Guangdong Universities(2022ZDZX4040)grateful for the support of the Youth Team Project of Wuhan Botanical Garden,Chinese Academy of Sciences
文摘The biogeochemical cycling on the Qinghai–Xizang Plateau is sensitive to climate change.Yet the response of fluvial nitrate(NO_(3)^(−))dynamics to climatic conditions on the plateau is poorly understood.Here,natural abundance isotopes were synthesized and^(15)N pairing experiments were carried out to systematically clarify the drivers of NO_(3)^(−)-N levels in an alpine river on the southeastern Qinghai–Xizang Plateau in winter.The natural abundance isotopes(δ^(15)N/δ^(18)O_(NO3))of the river waters suggested that soil organic nitrogen(SON)was the primary source of riverine NO_(3)^(−)-N(96.5%±2.2%),and substantial biological NO_(3)^(−)removal occurred in the catchment.The ^(15)N pairing techniques quantified that the removal of NO_(3)^(−)in soils and river sediments,i.e.,dissimilatory NO_(3)^(−)reduction to ammonium(DNRA)denitrification,and anammox,was prevalent,which outcompeted nitrification.As SON dominated the NO_(3)^(−)sources,we focused on the drivers of NO_(3)^(−)production-related processes in the soils.The denitrification rates in the soils were largely controlled by moisture.
