Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well understood.In this study,the August 2019 distributi...Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well understood.In this study,the August 2019 distributions of salinity,nutrients [nitrate(NO_(3)^(-)),nitrite,ammonium,and phosphate],and the stable isotopic composition of NO_(3)^(-)(δ^(15)N and δ^(18)O) were used to investigate sources of dissolved inorganic nitrogen(DIN) to Hangzhou B ay.Spatial distributions of nitrate,salinity,and nitrate δ^(18)O indicate that the Qiantang River,the Changjiang River,and nearshore coastal waters may all contribute nitrate to the bay.Based on the isotopic compositions of nitrate in these potential source waters and conservative mixing of nitrate in our study area,we suggest that the NO_(3)^(- )in Hangzhou B ay was likely derived mainly from soils,synthetic N fertilizer,and manure and sewage.End-member modeling indicates that in the upper half of the bay,the Qiantang River was a very important DIN source,possibly contributing more than 50% of DIN in the bay head area.In the lower half of the bay,DIN was sourced mainly from strongly intruding coastal water.DIN coming directly from the Changjiang River made a relatively small contribution to Hangzhou Bay DIN in August 2019.展开更多
In this study,the nitrogen and oxygen isotope compositions of nitrite in the upper 150 m water column of the Amundsen Sea in the summer of 2019 and 2020 were measured to reveal the distribution and transformation of n...In this study,the nitrogen and oxygen isotope compositions of nitrite in the upper 150 m water column of the Amundsen Sea in the summer of 2019 and 2020 were measured to reveal the distribution and transformation of nitrite in the euphotic zone of the Southern Ocean.We found that primary nitrite maxima(PNMs)are widely present in the Amundsen Sea,where the depth of occurrence deepens from east to west and nitrite concentrations increases.Evidence from dual isotopes suggests that the formation of PNMs in all regions of the Amundsen Sea is dominated by ammonia oxidation.More importantly,the nitrogen and oxygen isotope compositions of nitrite in the Amundsen Sea mixed layer are abnormal,and their depth profiles are mirror symmetrical.Isotopic anomalies exhibit spatial variations,with central surface water having the lowest nitrogen isotope composition(−89.9‰±0.2‰)and western surface water having the highest oxygen isotope composition(63.3‰±0.3‰).Isotopic exchange reaction between nitrate and nitrite is responsible for these isotope anomalies,as both nitrogen and oxygen isotopes have large isotopic fractionation and opposite enrichment effects.This proves that isotopic exchange reaction operates extensively in different regions of the Amundsen Sea.Our study highlights the unique role of dual isotopes of nitrite in deepening the understanding of nitrogen cycle.Further studies on ammonia oxidation and isotopic exchange between nitrate and nitrite are warranted in the future to understand their roles in the nitrogen cycle in the Southern Ocean.展开更多
In recent years,emergent pollutant’s accidents have occurred frequently in China,causing serious harm to the ecological environment.In this study,the impact of an accidental fire and explosion at Tianjin Port in 2015...In recent years,emergent pollutant’s accidents have occurred frequently in China,causing serious harm to the ecological environment.In this study,the impact of an accidental fire and explosion at Tianjin Port in 2015 on the atmosphere over the Bohai Sea was explored.Results showed sharp increases in the concentrations of several important components of fine particulate matter(e.g.NO3−,SO42−,NH4+,organic carbon,elemental carbon)over Beihuangcheng Island after the explosion.Among them,NO3−was most affected(about 10 days),with a maximum concentration of 16.45μg m−3.Theδ15N-NO3−ranged from−1.58‰to+8.74‰,with an average of+2.79‰±3.32‰.Influenced by the explosion,δ15N-NO3−decreased significantly,which was in accordance with the industrial processes of explosives.Theδ18O-NO3−varied between+49.40‰and+69.52‰,and showed a marked increase(+66.62‰±3.92‰)in the explosion-affected period.Using Monte Carlo simulation,the•OH pathway for NO3−formation was 51.79%±10.94%at that time—much lower than in the regular period.The elevated dry deposition of NO3−caused by the explosion was 266.08μmol N m−2 d−1 over the Bohai Sea—again,much higher than in the regular period.With the dry nitrogen deposition of NH4+(42.41μmol N m−2 d−1),the total nitrogen deposition increased by 308.49μmol N m−2 d−1,leading to severe ecological risk.Through the inverse computation of the dry deposition flux of NO3−,the affected area over the Bohai Sea was less than 1.42×104 km2,which is about 20%of the total area.展开更多
THK N<sub>2</sub>O is an important greenhouse gas. In the steady state the stable isotopic composition of nitrogenand oxygen in tropospheric N<sub>2</sub>O is balanced by isotopically light N&l...THK N<sub>2</sub>O is an important greenhouse gas. In the steady state the stable isotopic composition of nitrogenand oxygen in tropospheric N<sub>2</sub>O is balanced by isotopically light N<sub>2</sub>O emitted from soils and oceans andisotopically heavy N<sub>2</sub>O as return flux from the stratosphere. However, no such balance was reached incalculations given by Kim and Craig. This serious discrepancy lied in the fact that only soil and oceanic sources were considered in Kim and Craig’s calculation and N<sub>2</sub>O emission from tropical forest soil wastaken as the global soil contribution. Progress since the 1990s in identifying additional sources of atmospheric N<sub>2</sub>O as well as in the estimation from various types of soil allows us to make more realistic assessment of nitrogen and oxygen isotope balance budgets in tropospheric N<sub>2</sub>O. In this note, modification willbe proposed of atmospheric N<sub>2</sub>O nitrogen and oxygen isotope budgets to Kim and Craig’s calculation. The static balance of nitrogen and oxygen isotopes in tropospheric N<sub>2</sub>O is expressed展开更多
基金The Zhejiang Provincial Natural Science Foundation of China under contract No.LZ22D060002the Key R&D Program of Zhejiang under contract No.2022C03044the National Key Research and Development Program of China under contract No.2021YFC3101702。
文摘Eutrophication caused by inputs of excess nitrogen(N) has become a serious environmental problem in Hangzhou Bay(China),but the sources of this nitrogen are not well understood.In this study,the August 2019 distributions of salinity,nutrients [nitrate(NO_(3)^(-)),nitrite,ammonium,and phosphate],and the stable isotopic composition of NO_(3)^(-)(δ^(15)N and δ^(18)O) were used to investigate sources of dissolved inorganic nitrogen(DIN) to Hangzhou B ay.Spatial distributions of nitrate,salinity,and nitrate δ^(18)O indicate that the Qiantang River,the Changjiang River,and nearshore coastal waters may all contribute nitrate to the bay.Based on the isotopic compositions of nitrate in these potential source waters and conservative mixing of nitrate in our study area,we suggest that the NO_(3)^(- )in Hangzhou B ay was likely derived mainly from soils,synthetic N fertilizer,and manure and sewage.End-member modeling indicates that in the upper half of the bay,the Qiantang River was a very important DIN source,possibly contributing more than 50% of DIN in the bay head area.In the lower half of the bay,DIN was sourced mainly from strongly intruding coastal water.DIN coming directly from the Changjiang River made a relatively small contribution to Hangzhou Bay DIN in August 2019.
基金The Impact and Response of Antarctic Seas to Climate Change under contract Nos IRASCC 02-01-01 and IRASCC 01-01-02Cthe National Natural Science Foundation of China under contract No.41721005.
文摘In this study,the nitrogen and oxygen isotope compositions of nitrite in the upper 150 m water column of the Amundsen Sea in the summer of 2019 and 2020 were measured to reveal the distribution and transformation of nitrite in the euphotic zone of the Southern Ocean.We found that primary nitrite maxima(PNMs)are widely present in the Amundsen Sea,where the depth of occurrence deepens from east to west and nitrite concentrations increases.Evidence from dual isotopes suggests that the formation of PNMs in all regions of the Amundsen Sea is dominated by ammonia oxidation.More importantly,the nitrogen and oxygen isotope compositions of nitrite in the Amundsen Sea mixed layer are abnormal,and their depth profiles are mirror symmetrical.Isotopic anomalies exhibit spatial variations,with central surface water having the lowest nitrogen isotope composition(−89.9‰±0.2‰)and western surface water having the highest oxygen isotope composition(63.3‰±0.3‰).Isotopic exchange reaction between nitrate and nitrite is responsible for these isotope anomalies,as both nitrogen and oxygen isotopes have large isotopic fractionation and opposite enrichment effects.This proves that isotopic exchange reaction operates extensively in different regions of the Amundsen Sea.Our study highlights the unique role of dual isotopes of nitrite in deepening the understanding of nitrogen cycle.Further studies on ammonia oxidation and isotopic exchange between nitrate and nitrite are warranted in the future to understand their roles in the nitrogen cycle in the Southern Ocean.
基金This research was financially supported by a project funded by the China Postdoctoral Science Foundation[grant numbers 2017LH020 and 2017M622815]the National Natural Science Foundation of China[grant numbers 41977190 and 41907198].
文摘In recent years,emergent pollutant’s accidents have occurred frequently in China,causing serious harm to the ecological environment.In this study,the impact of an accidental fire and explosion at Tianjin Port in 2015 on the atmosphere over the Bohai Sea was explored.Results showed sharp increases in the concentrations of several important components of fine particulate matter(e.g.NO3−,SO42−,NH4+,organic carbon,elemental carbon)over Beihuangcheng Island after the explosion.Among them,NO3−was most affected(about 10 days),with a maximum concentration of 16.45μg m−3.Theδ15N-NO3−ranged from−1.58‰to+8.74‰,with an average of+2.79‰±3.32‰.Influenced by the explosion,δ15N-NO3−decreased significantly,which was in accordance with the industrial processes of explosives.Theδ18O-NO3−varied between+49.40‰and+69.52‰,and showed a marked increase(+66.62‰±3.92‰)in the explosion-affected period.Using Monte Carlo simulation,the•OH pathway for NO3−formation was 51.79%±10.94%at that time—much lower than in the regular period.The elevated dry deposition of NO3−caused by the explosion was 266.08μmol N m−2 d−1 over the Bohai Sea—again,much higher than in the regular period.With the dry nitrogen deposition of NH4+(42.41μmol N m−2 d−1),the total nitrogen deposition increased by 308.49μmol N m−2 d−1,leading to severe ecological risk.Through the inverse computation of the dry deposition flux of NO3−,the affected area over the Bohai Sea was less than 1.42×104 km2,which is about 20%of the total area.
文摘THK N<sub>2</sub>O is an important greenhouse gas. In the steady state the stable isotopic composition of nitrogenand oxygen in tropospheric N<sub>2</sub>O is balanced by isotopically light N<sub>2</sub>O emitted from soils and oceans andisotopically heavy N<sub>2</sub>O as return flux from the stratosphere. However, no such balance was reached incalculations given by Kim and Craig. This serious discrepancy lied in the fact that only soil and oceanic sources were considered in Kim and Craig’s calculation and N<sub>2</sub>O emission from tropical forest soil wastaken as the global soil contribution. Progress since the 1990s in identifying additional sources of atmospheric N<sub>2</sub>O as well as in the estimation from various types of soil allows us to make more realistic assessment of nitrogen and oxygen isotope balance budgets in tropospheric N<sub>2</sub>O. In this note, modification willbe proposed of atmospheric N<sub>2</sub>O nitrogen and oxygen isotope budgets to Kim and Craig’s calculation. The static balance of nitrogen and oxygen isotopes in tropospheric N<sub>2</sub>O is expressed
