Aquaculture ponds have emerged as a significant contributor to greenhouse gas(GHG)emissions.We measured methane(CH_(4)),carbon dioxide(CO_(2)),and nitrous oxide(N_(2)O)emissions in ponds,all located in Jiangsu Provinc...Aquaculture ponds have emerged as a significant contributor to greenhouse gas(GHG)emissions.We measured methane(CH_(4)),carbon dioxide(CO_(2)),and nitrous oxide(N_(2)O)emissions in ponds,all located in Jiangsu Province,with different fish and management practices over an entire cycle.All ponds emitted these gases,with higher CH_(4) and N_(2)O levels during fish growth than stocking period.The highest CH_(4) and N_(2)O fluxes were found in the Crucian carp(Carassius auratus)pond with up to 16,512±3015μmol/(m^(2)·h)and 5.54±0.31μmol/(m^(2)·h),respectively.CH_(4) was the primary contributor to the global warming potential in traditional earthen ponds,accounting for an average contribution rate of 87.7%.The dissolved oxygen(DO)concentration was the water quality parameter that most significantly influenced the CO_(2)flux,while pH acted as its primary regulator.The GHG emission intensity per unit of fish production in traditional earthen ponds was 197 times higher than that in-pond raceway systems.Largemouth bass(Micropterus salmoides)and Crucian carp ponds exhibited CH_(4) diffusion fluxes at the sediment-water interface,which were>20 times higher than those at the water-air interface.Our results further suggest that stocking density and feed amount significantly influence the variations in GHG emissions among the ponds with the in-pond raceway system having low carbon emissions and being high yield aquaculture system compared to traditional earthen ponds.The water depth and DO concentration can be manipulated to reduce GHG emissions across the various interfaces.展开更多
Different N and P fractions inmicrocosm incubation experiment was measured using highresolution in-situ Peeper and DGT techniques combining with sequential extraction procedure.The results showed the synchronous desor...Different N and P fractions inmicrocosm incubation experiment was measured using highresolution in-situ Peeper and DGT techniques combining with sequential extraction procedure.The results showed the synchronous desorption and release of PO_(4)^(3-),S^(2-)and Fe^(2+)from the solid soil-originated sediment.This trend indicated that the significant reduction of Fe-P and SO_(4)^(2-) occurred in the pore water during the inundation.The concentrations of PO_(4)^(3-) in the overlying water and pore water increased to more than 0.1 and 0.2 mg/L at the beginning of the incubation experiment.Decreased NO_(3)^(-) concentrations from more than 1.5 mg/L to less than 0.5 mg/L combining with increasing NH^(4+) concentrations from less than 1mg/L tomore than 5 mg/L suggested the remarkable NO_(3)-reduction via dissimilatory nitrate reduction to ammonia(DNRA)pathway over time.High NH^(4+) concentrations in the pore water aggravated the release of Fe^(2+) through reduction of Fe(Ⅲ)-P as electric acceptors under anaerobic conditions.This process further stimulated the remarkable releasing of labile PO_(4)^(3-) from the solid phase to the solution and potential diffusion into overlying water.Additionally,high S^(2-) concentration at deeper layer indicated the reduction and releasing of S^(2-)from oxidation states,which can stimulated the NO_(3)^(-)reduction and the accumulation of NH^(4+)in the pore water.This process can also provoke the reduction of Fe-P as electric acceptors following the release of labile PO_(4)^(3-)into pore water.Generally,inundation potentially facilitate the desorption of labile P and attention should be paid during the reclaiming lake from polder.展开更多
Aerobic anoxygenic phototrophic bacteria(AAPB)repre sent a major group of bacterioplankton assemblages in many water systems and some are assumed to be closely associated with phytoplankton.However,studies on relation...Aerobic anoxygenic phototrophic bacteria(AAPB)repre sent a major group of bacterioplankton assemblages in many water systems and some are assumed to be closely associated with phytoplankton.However,studies on relationships between AAPB and cyanobacterial blooms are in scarcity.The dynamics of the abundance and diversity of AAPB was compared based on pufM gene in Meiliang Bay(featured by cyanobacterial blooms)and East Bay(featured by macrophyte)of Taihu Lake,a shallow subtropical lake in the East China plain.AAPB abundance was not significantly different between the two sites,and they were positively correlated with dissolved organic carbon(DOC)concentration.The ratios of AAPB to total bacteria varied from 3.4%to 11.5%and peaked in winter in both site s.No significant differences of AAPB community compositions were detected between the two sites,but there was a separation between warm seasons(June,August,and October)and cold seasons(December,February,and April).Rhizobiales and Limnohabitans-like pufM sequences were significantly contributors for the difference between two seasons,and specially enriched in cold seasons.Chlorophyll a(Ch1 a)and DOC were the most significant variables influencing the AAPB community structure.Furthermore,Porphyrobacter and Rhodospirillales-like pufM sequences were positively correlated with Ch1 a,indicating potential influence of cyanobacterial blooms on these AAPB taxa.These results suggested that diverse AAPB ecotypes coexisted in Taihu Lake,and their ecological role in carbon cycling in the lake may not be ignored.展开更多
Colony formation of cyanobacteria is crucial for the formation of surface blooms in lakes.However,the underlying mechanisms of colony formation involving in physiological and cell surface characteristics remain to not...Colony formation of cyanobacteria is crucial for the formation of surface blooms in lakes.However,the underlying mechanisms of colony formation involving in physiological and cell surface characteristics remain to not well be established.Six cyanobacterial Microcystis strains(including both unicellular and colonial ones)were employed to estimate the influences of their physiological traits and the composition of extracellular polymeric substances(EPS)on colony or aggregate formation.Results show that raising the number of the photosynthetic reaction center and light-harvesting antenna in the PSII and reducing the growth rate were the major physiological strategies of Microcystis to produce excess EPS enhancing colony formation.Tightly bound EPS(T-EPS)was responsible for colony formation,which approximately accounted for 50%of the total amount of EPS.Five fluorescent components(protein-,tryptophan-,and tyrosine-like components and two humic-like components)were found in the T-EPS,although the amounts of these components varied with strains.Importantly,colonial strains contained much higher tyrosine-like substances than unicellular ones.We suggest that tyrosine-like substances might serve as a crosslinking agent to connect other polymers in EPS(e.g.,proteins or polysaccharides)for colony formation.Our findings identified key physiological traits and chemical components of EPS for colony formation in Microcystis,which can contribute to a better understanding on the formation of Microcystis blooms.展开更多
基金supported by the National Key Research and Development Program of China(No.SQ2024YFE0102696)the Provincial Science and Technology Innovative Program for Carbon Peak and Carbon Neutrality of Jiangsu of China(No.BE2022422)supported by the TÜBITAK program BIDEB2232(No.118C250).
文摘Aquaculture ponds have emerged as a significant contributor to greenhouse gas(GHG)emissions.We measured methane(CH_(4)),carbon dioxide(CO_(2)),and nitrous oxide(N_(2)O)emissions in ponds,all located in Jiangsu Province,with different fish and management practices over an entire cycle.All ponds emitted these gases,with higher CH_(4) and N_(2)O levels during fish growth than stocking period.The highest CH_(4) and N_(2)O fluxes were found in the Crucian carp(Carassius auratus)pond with up to 16,512±3015μmol/(m^(2)·h)and 5.54±0.31μmol/(m^(2)·h),respectively.CH_(4) was the primary contributor to the global warming potential in traditional earthen ponds,accounting for an average contribution rate of 87.7%.The dissolved oxygen(DO)concentration was the water quality parameter that most significantly influenced the CO_(2)flux,while pH acted as its primary regulator.The GHG emission intensity per unit of fish production in traditional earthen ponds was 197 times higher than that in-pond raceway systems.Largemouth bass(Micropterus salmoides)and Crucian carp ponds exhibited CH_(4) diffusion fluxes at the sediment-water interface,which were>20 times higher than those at the water-air interface.Our results further suggest that stocking density and feed amount significantly influence the variations in GHG emissions among the ponds with the in-pond raceway system having low carbon emissions and being high yield aquaculture system compared to traditional earthen ponds.The water depth and DO concentration can be manipulated to reduce GHG emissions across the various interfaces.
基金supported by the Jiangsu Water Conservancy Science and Technology Project (No. 2021038)the National Natural Science Foundation of China (Nos. 41503099, 31972813)the Jiangsu Province Scientific Research Foundation (Nos. CX(20)2026, YDCG-2021–005)。
文摘Different N and P fractions inmicrocosm incubation experiment was measured using highresolution in-situ Peeper and DGT techniques combining with sequential extraction procedure.The results showed the synchronous desorption and release of PO_(4)^(3-),S^(2-)and Fe^(2+)from the solid soil-originated sediment.This trend indicated that the significant reduction of Fe-P and SO_(4)^(2-) occurred in the pore water during the inundation.The concentrations of PO_(4)^(3-) in the overlying water and pore water increased to more than 0.1 and 0.2 mg/L at the beginning of the incubation experiment.Decreased NO_(3)^(-) concentrations from more than 1.5 mg/L to less than 0.5 mg/L combining with increasing NH^(4+) concentrations from less than 1mg/L tomore than 5 mg/L suggested the remarkable NO_(3)-reduction via dissimilatory nitrate reduction to ammonia(DNRA)pathway over time.High NH^(4+) concentrations in the pore water aggravated the release of Fe^(2+) through reduction of Fe(Ⅲ)-P as electric acceptors under anaerobic conditions.This process further stimulated the remarkable releasing of labile PO_(4)^(3-) from the solid phase to the solution and potential diffusion into overlying water.Additionally,high S^(2-) concentration at deeper layer indicated the reduction and releasing of S^(2-)from oxidation states,which can stimulated the NO_(3)^(-)reduction and the accumulation of NH^(4+)in the pore water.This process can also provoke the reduction of Fe-P as electric acceptors following the release of labile PO_(4)^(3-)into pore water.Generally,inundation potentially facilitate the desorption of labile P and attention should be paid during the reclaiming lake from polder.
基金Supported by the National Natural Science Foundation of China(Nos.31971449,31370509,31100363)the CAS-SAFEA International Partnership Program for Creative Research Teams(CN)(No.KZZD-EWTZ-08)the startup funds from Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2011QD05)。
文摘Aerobic anoxygenic phototrophic bacteria(AAPB)repre sent a major group of bacterioplankton assemblages in many water systems and some are assumed to be closely associated with phytoplankton.However,studies on relationships between AAPB and cyanobacterial blooms are in scarcity.The dynamics of the abundance and diversity of AAPB was compared based on pufM gene in Meiliang Bay(featured by cyanobacterial blooms)and East Bay(featured by macrophyte)of Taihu Lake,a shallow subtropical lake in the East China plain.AAPB abundance was not significantly different between the two sites,and they were positively correlated with dissolved organic carbon(DOC)concentration.The ratios of AAPB to total bacteria varied from 3.4%to 11.5%and peaked in winter in both site s.No significant differences of AAPB community compositions were detected between the two sites,but there was a separation between warm seasons(June,August,and October)and cold seasons(December,February,and April).Rhizobiales and Limnohabitans-like pufM sequences were significantly contributors for the difference between two seasons,and specially enriched in cold seasons.Chlorophyll a(Ch1 a)and DOC were the most significant variables influencing the AAPB community structure.Furthermore,Porphyrobacter and Rhodospirillales-like pufM sequences were positively correlated with Ch1 a,indicating potential influence of cyanobacterial blooms on these AAPB taxa.These results suggested that diverse AAPB ecotypes coexisted in Taihu Lake,and their ecological role in carbon cycling in the lake may not be ignored.
基金Supported by the National Natural Science Foundation of China(No.32071569)the Scientific Instruments and Equipment Development Project+2 种基金Chinese Academy of Sciences,2020(No.YJKYYQ20200048)the Fundamental Research Funds for the Central Universities(No.B210202010)the China Postdoctoral Foundation(No.2020M681472)。
文摘Colony formation of cyanobacteria is crucial for the formation of surface blooms in lakes.However,the underlying mechanisms of colony formation involving in physiological and cell surface characteristics remain to not well be established.Six cyanobacterial Microcystis strains(including both unicellular and colonial ones)were employed to estimate the influences of their physiological traits and the composition of extracellular polymeric substances(EPS)on colony or aggregate formation.Results show that raising the number of the photosynthetic reaction center and light-harvesting antenna in the PSII and reducing the growth rate were the major physiological strategies of Microcystis to produce excess EPS enhancing colony formation.Tightly bound EPS(T-EPS)was responsible for colony formation,which approximately accounted for 50%of the total amount of EPS.Five fluorescent components(protein-,tryptophan-,and tyrosine-like components and two humic-like components)were found in the T-EPS,although the amounts of these components varied with strains.Importantly,colonial strains contained much higher tyrosine-like substances than unicellular ones.We suggest that tyrosine-like substances might serve as a crosslinking agent to connect other polymers in EPS(e.g.,proteins or polysaccharides)for colony formation.Our findings identified key physiological traits and chemical components of EPS for colony formation in Microcystis,which can contribute to a better understanding on the formation of Microcystis blooms.
