The potential feedback by intracellular nitrogen pools on maximum N uptake (NH + 4) rate were determined for Gracilaria tenuistipitata var. liui and Ulva pertusa. The results of correlation matrix analyz...The potential feedback by intracellular nitrogen pools on maximum N uptake (NH + 4) rate were determined for Gracilaria tenuistipitata var. liui and Ulva pertusa. The results of correlation matrix analyzing showed that the surge uptake of ammonium seemed related to rapid changes in small intracellular pools of inorganic nitrogen or small peptide and amino acids rather than to changes in TN content of the macroalgae. The assimilation rates of nitrogen of U. pertusa and G. tenuistipitata increased slowly during N starvation and were mainly regulated by amino acids and some incorporation of amino acids into macromolecules. From ecological point of view, the fast growing and uptaking nutrient U. pertusa is more suitable to improve water quality in integrated shrimp culture ponds in which external nutrient supplies are usually high and constant during the culture period, while G. tenuistipitata var. liui is more suitable to be polycultured in a waters with intermittence supply of nutrients.展开更多
Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophica...Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophication ecological risk.Taihu Lake is a typical eutrophic shallowlake,suffering fromcyanobacteria blooms for decades due to excessive exogenous nutrient load.In this study,the coupling relationship between basin N loss and lake responsewas established by combining N flow and exogenous nutrient load.The results showed striking spatiotemporal differences and the large tributaries input themajority of N.Three evolution stages of the lake ecosystem were classified,i.e.,Stage A(1980–1997)with slow increasing N load;Stage B(1998–2006)with high-level N load despite some controlling methods;Stage C(2007 to present)with the strengthening of N management in lake basin after the Water Crisis,the N load has gradually decreased,while the water flow is increasing by the year.Environmental N export in the basin was 581.46 kg/ha N in 2021,and a total of 32.06 Gg N was finally drawn into the lake.Over the recent two decades,the noticeable expansion of built-up land from 8.21%to 21.04%associated with its environmental impacts i.e.,urban heat island effect,hard pavement,and ecological fragility deserves attention.Accordingly,the rapid climate change of the basin became the key factor driving the tributaries’hydrologic conditions(r_(∂)=0.945).The developed social economy dominated the sewage discharge(r_(∂)=0.857).The N inputs and losses to the environment in the basin can be further exacerbated without control.Meanwhile,the lake would respond to the exogenous input.In addition to the self-cleaning part of the lake,the N accumulation rate of the surface sediment ranged from 3.29 to 10.77 g N/(m^(2)·yr)of Taihu Lake.To meet the pollutant control target,around 66.28 Gg anthropogenic N needs to be reduced in the upper stream area yearly.Clarifying the N flow and its environmental burden can mitigate its damage to the ecosystem and take on the refined management on the watershed scale.展开更多
It is of important referential values for the further understanding of the effects of fertilization on greenhouse gas emissions and the effects of winter green manure on soil carbon pool to study the effects of fertil...It is of important referential values for the further understanding of the effects of fertilization on greenhouse gas emissions and the effects of winter green manure on soil carbon pool to study the effects of fertilization on the greenhouse gas emissions and soil carbon pool during the growing season of winter Chinese milk vetch in the process of rice cultivation.This study investigated the effects of nitrogen application in late rice season on the yield of the succeeding Chinese milk vetch and greenhouse gas emissions as well as the soil carbon pool characteristics after the winter planting of Chinese milk vetch with the winter idling of no nitrogen application as the control.The results showed that the yield of Chinese milk vetch was the highest under the nitrogen application of 225 kg/hm^2 in the late rice season,reaching up to 18 388.97 kg/hm^2,which was significantly different from other treatments( P <0.05).Nitrogen application in late rice season increased the emissions of N_2 O,CH_4,CO_2 and global warming potential( GWP) in the growing season of Chinese milk vetch.Compared with the winter idling treatment,winter planting of Chinese milk vetch significantly increased the soil organic carbon and soil carbon pool management index.The yield of Chinese milk vetch was significantly positively correlated with N_2O and CH_4 emissions( P < 0.05),while it presented extremely significant positive correlations with CO_2 emissions,GWP,active organic carbon,and carbon pool management index( P < 0.01).Nitrogen application in the late rice season increased the emissions of N_2 O,CH_4,CO_2,and enhanced the greenhouse gas emission potential during the growing season of Chinese milk vetch.Therefore,without reducing the yield of rice,reducing the amount of nitrogen fertilizer in rice could reduce the greenhouse gas emissions in the growing season of succeeding Chinese milk vetch.展开更多
This paper deals with the N storage of Gracilaria tenuistipitata var. liui and Ulva pertusa under ammonium enrichment and starvation. After 10 days of ammonium enrichment, ammonium NH4,+ free amino acid (FAA), protein...This paper deals with the N storage of Gracilaria tenuistipitata var. liui and Ulva pertusa under ammonium enrichment and starvation. After 10 days of ammonium enrichment, ammonium NH4,+ free amino acid (FAA), protein (pro), chlorophyll (Chi), phycoerythrin (PE) and total dissolved nitrogen (TDN) of the two macroalgae increased significantly. Total nitrogen (TN) increased significantly from 3.65% to 5.78% dry weight of G. tenuistipitata var. liui and 2.82% to 5.07% dw of U. pertusa, respectively. Protein and FAA were the most important N storage pools in the macroalgae. During N-starvation period, individual N pools of the two species were depleted at exponential rates. Each N pool in U. pertusa decreased more rapidly than in G. tenuistipitata, var. liui and the latter was able to sustain fast growth for more time ( > 20 days) than U. pertusa. N demands for supporting growth were different between the two species, U. pertusa grew more rapidly and had higher N demands than G. tenuistipitata var. liui did.展开更多
Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposit...Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposition was determined at three agricultural sites using a manual integrated total nitrogen input (ITNI) system during growth of winter wheat (Triticum aestivum L.) and Italian ryegrass (Lolium multiflorum Lam.) from September 2005 to May 2006. Total estimated N deposition averaged 54.9 and 43.2 kg N/hm2 across the three sites when wheat was grown to flowering and maturing, respectively. The average value was 50.2 kg N/hm2 when ryegrass was the indicator plant. Both indicator species gave similar total airborne N input results. The intermediate level of N supplied resulted in the highest N deposition, and the ratio of N acquired from deposition to total N content of the whole system decreased with increasing N supply to the roots. The contribution of atmospheric N to the total N content of the wheat and ryegrass sand culture systems ranged from 10% to 24%.展开更多
文摘The potential feedback by intracellular nitrogen pools on maximum N uptake (NH + 4) rate were determined for Gracilaria tenuistipitata var. liui and Ulva pertusa. The results of correlation matrix analyzing showed that the surge uptake of ammonium seemed related to rapid changes in small intracellular pools of inorganic nitrogen or small peptide and amino acids rather than to changes in TN content of the macroalgae. The assimilation rates of nitrogen of U. pertusa and G. tenuistipitata increased slowly during N starvation and were mainly regulated by amino acids and some incorporation of amino acids into macromolecules. From ecological point of view, the fast growing and uptaking nutrient U. pertusa is more suitable to improve water quality in integrated shrimp culture ponds in which external nutrient supplies are usually high and constant during the culture period, while G. tenuistipitata var. liui is more suitable to be polycultured in a waters with intermittence supply of nutrients.
基金supported by the National Key Research and Development Program of China(No.2021YFC3201502)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_1830).
文摘Various forms of nitrogen(N)discharged by high-intensity human activities in the Yangtze River Delta are transported into the lake along the river channel,accelerating the lake’s N cycle and increasing the eutrophication ecological risk.Taihu Lake is a typical eutrophic shallowlake,suffering fromcyanobacteria blooms for decades due to excessive exogenous nutrient load.In this study,the coupling relationship between basin N loss and lake responsewas established by combining N flow and exogenous nutrient load.The results showed striking spatiotemporal differences and the large tributaries input themajority of N.Three evolution stages of the lake ecosystem were classified,i.e.,Stage A(1980–1997)with slow increasing N load;Stage B(1998–2006)with high-level N load despite some controlling methods;Stage C(2007 to present)with the strengthening of N management in lake basin after the Water Crisis,the N load has gradually decreased,while the water flow is increasing by the year.Environmental N export in the basin was 581.46 kg/ha N in 2021,and a total of 32.06 Gg N was finally drawn into the lake.Over the recent two decades,the noticeable expansion of built-up land from 8.21%to 21.04%associated with its environmental impacts i.e.,urban heat island effect,hard pavement,and ecological fragility deserves attention.Accordingly,the rapid climate change of the basin became the key factor driving the tributaries’hydrologic conditions(r_(∂)=0.945).The developed social economy dominated the sewage discharge(r_(∂)=0.857).The N inputs and losses to the environment in the basin can be further exacerbated without control.Meanwhile,the lake would respond to the exogenous input.In addition to the self-cleaning part of the lake,the N accumulation rate of the surface sediment ranged from 3.29 to 10.77 g N/(m^(2)·yr)of Taihu Lake.To meet the pollutant control target,around 66.28 Gg anthropogenic N needs to be reduced in the upper stream area yearly.Clarifying the N flow and its environmental burden can mitigate its damage to the ecosystem and take on the refined management on the watershed scale.
基金Supported by the National Key Research and Development Program(No.2016YFD0300208)the National Natural Science Foundation of China(No.41661070)
文摘It is of important referential values for the further understanding of the effects of fertilization on greenhouse gas emissions and the effects of winter green manure on soil carbon pool to study the effects of fertilization on the greenhouse gas emissions and soil carbon pool during the growing season of winter Chinese milk vetch in the process of rice cultivation.This study investigated the effects of nitrogen application in late rice season on the yield of the succeeding Chinese milk vetch and greenhouse gas emissions as well as the soil carbon pool characteristics after the winter planting of Chinese milk vetch with the winter idling of no nitrogen application as the control.The results showed that the yield of Chinese milk vetch was the highest under the nitrogen application of 225 kg/hm^2 in the late rice season,reaching up to 18 388.97 kg/hm^2,which was significantly different from other treatments( P <0.05).Nitrogen application in late rice season increased the emissions of N_2 O,CH_4,CO_2 and global warming potential( GWP) in the growing season of Chinese milk vetch.Compared with the winter idling treatment,winter planting of Chinese milk vetch significantly increased the soil organic carbon and soil carbon pool management index.The yield of Chinese milk vetch was significantly positively correlated with N_2O and CH_4 emissions( P < 0.05),while it presented extremely significant positive correlations with CO_2 emissions,GWP,active organic carbon,and carbon pool management index( P < 0.01).Nitrogen application in the late rice season increased the emissions of N_2 O,CH_4,CO_2,and enhanced the greenhouse gas emission potential during the growing season of Chinese milk vetch.Therefore,without reducing the yield of rice,reducing the amount of nitrogen fertilizer in rice could reduce the greenhouse gas emissions in the growing season of succeeding Chinese milk vetch.
文摘This paper deals with the N storage of Gracilaria tenuistipitata var. liui and Ulva pertusa under ammonium enrichment and starvation. After 10 days of ammonium enrichment, ammonium NH4,+ free amino acid (FAA), protein (pro), chlorophyll (Chi), phycoerythrin (PE) and total dissolved nitrogen (TDN) of the two macroalgae increased significantly. Total nitrogen (TN) increased significantly from 3.65% to 5.78% dry weight of G. tenuistipitata var. liui and 2.82% to 5.07% dw of U. pertusa, respectively. Protein and FAA were the most important N storage pools in the macroalgae. During N-starvation period, individual N pools of the two species were depleted at exponential rates. Each N pool in U. pertusa decreased more rapidly than in G. tenuistipitata, var. liui and the latter was able to sustain fast growth for more time ( > 20 days) than U. pertusa. N demands for supporting growth were different between the two species, U. pertusa grew more rapidly and had higher N demands than G. tenuistipitata var. liui did.
基金the One-hundred Talents Program of CAS,the Special Fund for Agricultural Profession (200803030)the Sino-German project (DFG Training Group,GK1070)
文摘Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposition was determined at three agricultural sites using a manual integrated total nitrogen input (ITNI) system during growth of winter wheat (Triticum aestivum L.) and Italian ryegrass (Lolium multiflorum Lam.) from September 2005 to May 2006. Total estimated N deposition averaged 54.9 and 43.2 kg N/hm2 across the three sites when wheat was grown to flowering and maturing, respectively. The average value was 50.2 kg N/hm2 when ryegrass was the indicator plant. Both indicator species gave similar total airborne N input results. The intermediate level of N supplied resulted in the highest N deposition, and the ratio of N acquired from deposition to total N content of the whole system decreased with increasing N supply to the roots. The contribution of atmospheric N to the total N content of the wheat and ryegrass sand culture systems ranged from 10% to 24%.
