The exchange of inorganic nutrients at the coastal sediment-water interface(SWI)plays a crucial role in regulating the nutrient budget in overlying water.The related studies mainly focus on the mid-to high-latitude re...The exchange of inorganic nutrients at the coastal sediment-water interface(SWI)plays a crucial role in regulating the nutrient budget in overlying water.The related studies mainly focus on the mid-to high-latitude regions,leaving a significant gap in the quantitative assessment of nutrient exchange and environmental controls at the SWI in lowlatitude coastal regions.We quantitatively assess the exchange of inorganic nutrients at the SWI in three tropical bays(Dongzhai Harbor,Xiaohai Lagoon,Qinglan Harbor).Sediments act as a source of ammonium,phosphate,and silicate,but for nitrate,sediments can be both a source and sink,although with substantial spatial and temporal variations in their fluxes.Labile organic matter is a critical regulator for the fluxes of inorganic nutrients at the SWI.The sedimentary nutrients input with high N/P molar ratio will alter the nutrient stoichiometry to mitigate the nitrogen limitation in coastal waters.However,the internal sediment release in these tropical bays plays a relative weak role in contributing to the nutrient addition in comparison with the other external nutrient sources including riverine input,submarine groundwater discharge,and atmospheric deposition.According to the global compilation on SWI nutrient fluxes,we propose that water column primary production and external inputs to interpret the variation in exchange and fluxes of nutrients at the SWI in different ecosystems.Such a conceptual understanding of these chain biogeochemical processes involving external nutrient input,primary production,particulate organic matter settling,and the accumulation and release of inorganic nutrients in sediments will be helpful for the scientific-based pollution prevent and control in coastal waters.展开更多
Characterized by scarce water resources and fragile ecosystems,Northwest China(NWC)has experienced a climate shift from warm-dry to warm-wet conditions since the 1980s that has garnered extensive concern in recent yea...Characterized by scarce water resources and fragile ecosystems,Northwest China(NWC)has experienced a climate shift from warm-dry to warm-wet conditions since the 1980s that has garnered extensive concern in recent years.In this study,the variability in extreme precipitation(EP)during 1961-2016 in different climate zones of NWC and the possible mechanisms for this variation are investigated.The results show that the EP trends significantly increased in most of the westerly zone(WZ)and plateau zone(PZ),while the EP trends did not significantly decrease in the monsoon zone(MZ).The start dates of extreme precipitation(SDEP)and end dates of extreme precipitation(EDEP)advanced and were postponed,respectively,in the WZ and PZ,while the opposite occurred in the MZ.Summer atmospheric circulation,water vapor transport,and atmospheric instability over NWC varied greatly with the interdecadal shift in EP before and after 1986.During 1986-2016,upper-level divergence and lower-level convergence occurred in the MZ and PZ,which strengthened ascending flow.In addition,the summer water vapor and atmospheric instability increased in the WZ and PZ.These characteristics created favorable conditions for increased occurrences of EP in the WZ and PZ in summer.Conversely,the upper-level convergence and lower-level divergence in the MZ strengthened descending flow.Decreases in summer water vapor and atmospheric instability occurred in the MZ after 1986.Hence,the environmental conditions in the MZ may have prevented the occurrence and development of EP in summer during 1986-2016.展开更多
基金The Major Science and Technology Plan of Hainan Province under contract No.ZDKJ2021008the Hainan Provincial Natural Science Foundation of China under contract No.623RC456+1 种基金the Hainan Province Science and Technology Special Fund under contract Nos ZDYF2021SHFZ064 and ZDYF2022SHFZ056the Collaborative Innovation Center of Marine Science and Technology in Hainan University under contract No.XTCX2022HYC19.
文摘The exchange of inorganic nutrients at the coastal sediment-water interface(SWI)plays a crucial role in regulating the nutrient budget in overlying water.The related studies mainly focus on the mid-to high-latitude regions,leaving a significant gap in the quantitative assessment of nutrient exchange and environmental controls at the SWI in lowlatitude coastal regions.We quantitatively assess the exchange of inorganic nutrients at the SWI in three tropical bays(Dongzhai Harbor,Xiaohai Lagoon,Qinglan Harbor).Sediments act as a source of ammonium,phosphate,and silicate,but for nitrate,sediments can be both a source and sink,although with substantial spatial and temporal variations in their fluxes.Labile organic matter is a critical regulator for the fluxes of inorganic nutrients at the SWI.The sedimentary nutrients input with high N/P molar ratio will alter the nutrient stoichiometry to mitigate the nitrogen limitation in coastal waters.However,the internal sediment release in these tropical bays plays a relative weak role in contributing to the nutrient addition in comparison with the other external nutrient sources including riverine input,submarine groundwater discharge,and atmospheric deposition.According to the global compilation on SWI nutrient fluxes,we propose that water column primary production and external inputs to interpret the variation in exchange and fluxes of nutrients at the SWI in different ecosystems.Such a conceptual understanding of these chain biogeochemical processes involving external nutrient input,primary production,particulate organic matter settling,and the accumulation and release of inorganic nutrients in sediments will be helpful for the scientific-based pollution prevent and control in coastal waters.
基金The authors would like to extend sincere gratitude for the support from the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0103)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA2006010101)+2 种基金the National Natural Science Foundation of China(91837208)the National Key Research and Development Program of China(2018YFC1505701)This work was jointly supported by the National Natural Science Foundation of China(42075043)and the Youth Innovation Promotion Association CAS.
文摘Characterized by scarce water resources and fragile ecosystems,Northwest China(NWC)has experienced a climate shift from warm-dry to warm-wet conditions since the 1980s that has garnered extensive concern in recent years.In this study,the variability in extreme precipitation(EP)during 1961-2016 in different climate zones of NWC and the possible mechanisms for this variation are investigated.The results show that the EP trends significantly increased in most of the westerly zone(WZ)and plateau zone(PZ),while the EP trends did not significantly decrease in the monsoon zone(MZ).The start dates of extreme precipitation(SDEP)and end dates of extreme precipitation(EDEP)advanced and were postponed,respectively,in the WZ and PZ,while the opposite occurred in the MZ.Summer atmospheric circulation,water vapor transport,and atmospheric instability over NWC varied greatly with the interdecadal shift in EP before and after 1986.During 1986-2016,upper-level divergence and lower-level convergence occurred in the MZ and PZ,which strengthened ascending flow.In addition,the summer water vapor and atmospheric instability increased in the WZ and PZ.These characteristics created favorable conditions for increased occurrences of EP in the WZ and PZ in summer.Conversely,the upper-level convergence and lower-level divergence in the MZ strengthened descending flow.Decreases in summer water vapor and atmospheric instability occurred in the MZ after 1986.Hence,the environmental conditions in the MZ may have prevented the occurrence and development of EP in summer during 1986-2016.
