Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean.The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese Nation...Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean.The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese National Antarctic Research Expedition in 2021.The relative standard deviations of the nitrate(NO_(3)-N),nitrite(NO_(2)-N),ammonium(NH_(4)-N),phosphate(PO_(4)-P),and silicate(SiO_(3)-Si)concentrations found in duplicate samples(n=2)were 1.01%,9.04%,6.45%,0.94%,and0.67%,respectively.The mean NO_(3)-N,NO_(2)-N,NH_(4)-N,PO_(4)-P,and SiO_(3)-Si concentrations in the mixed layer were 26.41±4.13,0.15±0.09,0.51±0.22,1.73±0.23,and 41.48±6.94μmol·L^(−1),respectively,and were higher than the relevant limitationconcentrations.The concentrations were generally bounded horizontally by the Southern Boundary(SB)of the Antarctic Circumpolar Current,the NO_(3)-N,NO_(2)-N,NH_(4)-N,and PO_(4)-P concentrations being higher northeast than southwest of the SB but the SiO_(3)-Si concentrations being higher southwest than northeast,indicating that the SB dominates nutrient distributions in themixed layer.The NO_(3)-N,NH_(4)-N,and PO_(4)-P concentrations gradually increased moving vertically down from the mixed layer to 200 m deep and then remained at 33.73±3.51,0.26±0.13,and 2.28±0.10μmol·L^(−1),respectively,to the bottom.The SiO_(3)-Si concentration increased as depth increased and reached a maximum in the bottom layer.The NO_(2)-N concentrationdecreased rapidly as depth increased and was~0μmol·L^(−1)at>150 m deep.Circumpolar Deep Water upwelling may cause high nutrient concentrations in shallower layers up to the 100 m layer between 62.5°S and 64°S.展开更多
Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate (vSiO3-Si, vPO4-P, vNH4-N, vNO2-N and vNO3-N) at the se...Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate (vSiO3-Si, vPO4-P, vNH4-N, vNO2-N and vNO3-N) at the sediment-water interface in the Jiaozhou Bay. Major factors influencing the exchange rates are discussed in detail, which include the dissolved inorganic nutrient concentrations in porewater (Cpw), water and clay contents, and grain size of the sediments (CH2O, Cclay and GSsed). The results may provide insight into the dynamics of nutrient transport and the environmental capacity of nutrients in Jiaozhou Bay, and should be beneficial to solving the problems caused by excessive nutrient input this area.展开更多
<span style="font-family:Verdana;">Kota Kinabalu Wetland is important</span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> h...<span style="font-family:Verdana;">Kota Kinabalu Wetland is important</span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> habited of mangrove, diverse aquatic flora and fauna as well as feeding stop for migratory birds. This wetland is inundated with the tidal flow, as connected with a small river and nearby coastal areas, thus. A study was carried out to determine the spatial distribution of dissolved inorganic nutrients and phytoplankton diversity at Kota Kinabalu (KK) Wetlands. Five stations, </span><span style="font-family:Verdana;">in </span><span style="font-family:""><span style="font-family:Verdana;">which river mouth of Likas Bay, river channel (two stations) and inundated area (two stations) in KK Wetland were selected for this study. </span><i><span style="font-family:Verdana;">In-situ</span></i><span style="font-family:Verdana;"> parameters of water, water for nutrients and phytoplankton samples were collected from May 2019 until October 2019. The highest concentration of nitrate (0.115 mg/L) was recorded at inundated area of wetland (S5) while the lowest nitrate concentration (0.0047 mg/L) was found at river (S3) flowing towards wetland. The concentrations of ammonia (0.2004 to 2.311 mg/L) were recorded relatively higher at every station compared to other dissolved inorganic nutrients (DIN). The concentration of phosphate was determined in the ranges of 0.0089 </span></span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;"> 0.0513 mg/L. Nitrate, ammonia and phosphate showed no significant difference (</span><i><span style="font-family:Verdana;">P </span></i><span style="font-family:Verdana;">= 0.737) in terms </span></span><span style="font-family:Verdana;">of </span><span style="font-family:""><span style="font-family:Verdana;">DIN concentration at all five sampling stations during the study period. Twenty-four genera of phytoplankton were identified, dominated by diatoms (55.29%), followed by dinoflagellates (24.95%), Chrysophyta (11.15%), Spirotrichea (5.28%) and Cyanophyta (3.33%). Dominating species throughout the study period include </span><i><span style="font-family:Verdana;">Chaetoceros </span></i><span style="font-family:Verdana;">sp., </span><i><span style="font-family:Verdana;">Pseduo-nitzschia </span></i><span style="font-family:Verdana;">sp., and </span><i><span style="font-family:Verdana;">Cylindrotheca closterium, Peridinium quinquecorne and Alexandrium sp. </span></i><span style="font-family:Verdana;">Phytoplankton species composition</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> w</span><span style="font-family:Verdana;">ere</span><span style="font-family:Verdana;"> observed the highest in river mouth area in July with the highest density of 12.115</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">× 10</span><sup><span style="font-family:Verdana;">4</span></sup><span style="font-family:Verdana;"> cells/</span></span><span style="font-family:Verdana;">mL</span><span style="font-family:""><span style="font-family:Verdana;">. The study showed that nutrient concentration was insignificant (</span><i><span style="font-family:Verdana;">P </span></i><span style="font-family:Verdana;">= 0.614) in altering the phytoplankton density, as influences with the tidal water.</span></span>展开更多
The seaweeds Chaetomorpha antennina, Gymnogongrus griffithsiae and Ulva fasciata were studied regarding tissue concentrations of total nitrogen, total phosphorus, total protein, hydrosoluble protein, total carbohydrat...The seaweeds Chaetomorpha antennina, Gymnogongrus griffithsiae and Ulva fasciata were studied regarding tissue concentrations of total nitrogen, total phosphorus, total protein, hydrosoluble protein, total carbohydrate, chlorophyll a and total carotenoid throughout a 39-month survey in two coastal environments of Rio de Janeiro State, Brazil. One of the sites (Itapuca Stone) has high concentrations of dissolved nutrients and an intense long-term process of cultural eutrophication;the second site (Bananal Inlet) is thought to have lower concentrations of dissolved nutrients and no relevant anthropic impact. Seaweeds experienced changes in the concentrations of the substances in the thalli;however they did not show any cyclic seasonal pattern, except for pigments, with lower values in summer in both sites. The differences found for each species in each sampling at the sites were small (e.g. U. fasciata, more total nitrogen at Itapuca Stone) or absent (e.g. C. antennina, no significant differences for hydrosoluble protein in the sites). Differences in the concentrations of dissolved nutrients in the sites did not generate contrasting chemical profiles in the seaweeds. There is no evidence of nitrogen- or phosphorus-limitation in any season. It is presumable that the concentrations of dissolved nutrients at the nutrient-poorer site are sufficient to generate high concentrations of the substances in the thalli of the species tested, similar to the concentrations measured in the eutrophic site. Experimental data are needed to elucidate the factors that promote the success of the species tested under contrasting nutrient availability and environmental disturbance.展开更多
Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus(P...Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus(PE-rich SYN) and phycocyanin-rich Synechococcus(PC-rich SYN). The effects of environmental factors on the alternation of the different Synechococcus groups were also elucidated. PE-rich SYN was detected in three surveys, whereas PC-rich SYN was detected in May and August, but not in November. The highest abundances of PE-rich SYN and PC-rich SYN were recorded in August and May, with mean values of 74.17×103 and 189.92×103 cells m L-1, respectively. From May to November, the relative abundance of PE-rich SYN increased, whereas that of PC-rich SYN declined. PE-rich and PC-rich SYN presented similar horizontal distributions with high abundance in the southern estuary in May, and in the western estuary in August. The abundances of PE-rich and PC-rich SYN were high at 27–32℃and salinity of 10–20. PC-rich SYN was not detected at < 24℃, and PC:PE-rich SYN decreased in abundance with salinity increase. When less than 20 mg L-1, suspended particulate matter(SPM) was helpful for Synechococcus growth. PE-rich SYN decreased in abundance when the concentration of dissolved inorganic nitrogen increased in May and November, and the concentration of phosphate increased in November. However, PC-rich SYN abundance and nutrients showed no correlation. Principal component analysis and regression analysis indicated that PE-rich SYN significantly correlated with the principal components that were affected by environmental factors.展开更多
The effects of biochar on methane emissions from soils are well understood.However,biochar effects on methane production from livestock have received less attention.In this study,a biochar-mineral supplement for lives...The effects of biochar on methane emissions from soils are well understood.However,biochar effects on methane production from livestock have received less attention.In this study,a biochar-mineral supplement for livestock was developed by pyrolyzing a mixture of wheat straw,aluminosilicates,iron sulfate,and zinc oxide at 600℃.The supplement was then activated using peracetic and propionic acids,and potassium nitrate.The activated biochar-mineral supplement was characterized using analytical techniques.A high surface area,a high concentration of oxygencontaining functional groups,and a high concentration of free radicals,associated with O and Fe unpaired electrons,assisted the supplement with catalysing the oxidation of methane.Microstructural analysis of the supplement suggested the formation of organo-mineral phases,rich in C,O,Fe,Si,Al,K and Ca,indicating that the biochar reacted with mineral additives to preserve them.To assess the potential of the supplement to reduce methane produced form livestock,an in vitro batch culture incubation was conducted(n=3)with rumen fluid sourced from Holstein–Friesian steers.The supplement was incubated at inclusion rates of 0%(control),1.5%,4.0%and 6.0%of dry matter(DM),with a Rhodes grass hay substrate.Compared to the control,the supplement reduced cumulative gas production by 10.1%and 12.7%and methane production by 19.03%and 29.32%after 48 h when included at 4.0%and 6.0%DM(P<0.05),respectively,without causing any detrimental impacts on fermentation parameters.The supplement assisted with reducing the concentration of dissolved mineral nutrients,such as P and Mg,when included at 4.0%and 6.0%DM(P<0.05).展开更多
基金financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change” (Grant nos. IRASCC 01-01-02A, IRASCC 02-02)the National Natural Science Foundation of China (NSFC) (Grant no. 41976228)
文摘Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean.The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese National Antarctic Research Expedition in 2021.The relative standard deviations of the nitrate(NO_(3)-N),nitrite(NO_(2)-N),ammonium(NH_(4)-N),phosphate(PO_(4)-P),and silicate(SiO_(3)-Si)concentrations found in duplicate samples(n=2)were 1.01%,9.04%,6.45%,0.94%,and0.67%,respectively.The mean NO_(3)-N,NO_(2)-N,NH_(4)-N,PO_(4)-P,and SiO_(3)-Si concentrations in the mixed layer were 26.41±4.13,0.15±0.09,0.51±0.22,1.73±0.23,and 41.48±6.94μmol·L^(−1),respectively,and were higher than the relevant limitationconcentrations.The concentrations were generally bounded horizontally by the Southern Boundary(SB)of the Antarctic Circumpolar Current,the NO_(3)-N,NO_(2)-N,NH_(4)-N,and PO_(4)-P concentrations being higher northeast than southwest of the SB but the SiO_(3)-Si concentrations being higher southwest than northeast,indicating that the SB dominates nutrient distributions in themixed layer.The NO_(3)-N,NH_(4)-N,and PO_(4)-P concentrations gradually increased moving vertically down from the mixed layer to 200 m deep and then remained at 33.73±3.51,0.26±0.13,and 2.28±0.10μmol·L^(−1),respectively,to the bottom.The SiO_(3)-Si concentration increased as depth increased and reached a maximum in the bottom layer.The NO_(2)-N concentrationdecreased rapidly as depth increased and was~0μmol·L^(−1)at>150 m deep.Circumpolar Deep Water upwelling may cause high nutrient concentrations in shallower layers up to the 100 m layer between 62.5°S and 64°S.
基金This research was partially supported by the National Natural Science Foundation of China (Nos 40136020 and 49976027)the Key Project of Chinese Ministry of Education (No.01110).
文摘Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate (vSiO3-Si, vPO4-P, vNH4-N, vNO2-N and vNO3-N) at the sediment-water interface in the Jiaozhou Bay. Major factors influencing the exchange rates are discussed in detail, which include the dissolved inorganic nutrient concentrations in porewater (Cpw), water and clay contents, and grain size of the sediments (CH2O, Cclay and GSsed). The results may provide insight into the dynamics of nutrient transport and the environmental capacity of nutrients in Jiaozhou Bay, and should be beneficial to solving the problems caused by excessive nutrient input this area.
文摘<span style="font-family:Verdana;">Kota Kinabalu Wetland is important</span><span style="font-family:Verdana;">ly</span><span style="font-family:Verdana;"> habited of mangrove, diverse aquatic flora and fauna as well as feeding stop for migratory birds. This wetland is inundated with the tidal flow, as connected with a small river and nearby coastal areas, thus. A study was carried out to determine the spatial distribution of dissolved inorganic nutrients and phytoplankton diversity at Kota Kinabalu (KK) Wetlands. Five stations, </span><span style="font-family:Verdana;">in </span><span style="font-family:""><span style="font-family:Verdana;">which river mouth of Likas Bay, river channel (two stations) and inundated area (two stations) in KK Wetland were selected for this study. </span><i><span style="font-family:Verdana;">In-situ</span></i><span style="font-family:Verdana;"> parameters of water, water for nutrients and phytoplankton samples were collected from May 2019 until October 2019. The highest concentration of nitrate (0.115 mg/L) was recorded at inundated area of wetland (S5) while the lowest nitrate concentration (0.0047 mg/L) was found at river (S3) flowing towards wetland. The concentrations of ammonia (0.2004 to 2.311 mg/L) were recorded relatively higher at every station compared to other dissolved inorganic nutrients (DIN). The concentration of phosphate was determined in the ranges of 0.0089 </span></span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;"> 0.0513 mg/L. Nitrate, ammonia and phosphate showed no significant difference (</span><i><span style="font-family:Verdana;">P </span></i><span style="font-family:Verdana;">= 0.737) in terms </span></span><span style="font-family:Verdana;">of </span><span style="font-family:""><span style="font-family:Verdana;">DIN concentration at all five sampling stations during the study period. Twenty-four genera of phytoplankton were identified, dominated by diatoms (55.29%), followed by dinoflagellates (24.95%), Chrysophyta (11.15%), Spirotrichea (5.28%) and Cyanophyta (3.33%). Dominating species throughout the study period include </span><i><span style="font-family:Verdana;">Chaetoceros </span></i><span style="font-family:Verdana;">sp., </span><i><span style="font-family:Verdana;">Pseduo-nitzschia </span></i><span style="font-family:Verdana;">sp., and </span><i><span style="font-family:Verdana;">Cylindrotheca closterium, Peridinium quinquecorne and Alexandrium sp. </span></i><span style="font-family:Verdana;">Phytoplankton species composition</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> w</span><span style="font-family:Verdana;">ere</span><span style="font-family:Verdana;"> observed the highest in river mouth area in July with the highest density of 12.115</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">× 10</span><sup><span style="font-family:Verdana;">4</span></sup><span style="font-family:Verdana;"> cells/</span></span><span style="font-family:Verdana;">mL</span><span style="font-family:""><span style="font-family:Verdana;">. The study showed that nutrient concentration was insignificant (</span><i><span style="font-family:Verdana;">P </span></i><span style="font-family:Verdana;">= 0.614) in altering the phytoplankton density, as influences with the tidal water.</span></span>
基金FAPERJ(Rio de Janeiro State Research Support Foundation)for the financial support to this study.
文摘The seaweeds Chaetomorpha antennina, Gymnogongrus griffithsiae and Ulva fasciata were studied regarding tissue concentrations of total nitrogen, total phosphorus, total protein, hydrosoluble protein, total carbohydrate, chlorophyll a and total carotenoid throughout a 39-month survey in two coastal environments of Rio de Janeiro State, Brazil. One of the sites (Itapuca Stone) has high concentrations of dissolved nutrients and an intense long-term process of cultural eutrophication;the second site (Bananal Inlet) is thought to have lower concentrations of dissolved nutrients and no relevant anthropic impact. Seaweeds experienced changes in the concentrations of the substances in the thalli;however they did not show any cyclic seasonal pattern, except for pigments, with lower values in summer in both sites. The differences found for each species in each sampling at the sites were small (e.g. U. fasciata, more total nitrogen at Itapuca Stone) or absent (e.g. C. antennina, no significant differences for hydrosoluble protein in the sites). Differences in the concentrations of dissolved nutrients in the sites did not generate contrasting chemical profiles in the seaweeds. There is no evidence of nitrogen- or phosphorus-limitation in any season. It is presumable that the concentrations of dissolved nutrients at the nutrient-poorer site are sufficient to generate high concentrations of the substances in the thalli of the species tested, similar to the concentrations measured in the eutrophic site. Experimental data are needed to elucidate the factors that promote the success of the species tested under contrasting nutrient availability and environmental disturbance.
基金supported by the National Natural Science Foundation of China (Nos. 41476098, 41276154)Special Scientific Research Funds for Central Non-profit Institutes of Yellow Sea Fisheries Research Institutes (2060302201502)
文摘Three surveys were carried out in Pearl River Estuary and adjacent coastal area in May, August, and November, 2013, to investigate the temporal and spatial variations of abundance of phycoerythrin-rich Synechococcus(PE-rich SYN) and phycocyanin-rich Synechococcus(PC-rich SYN). The effects of environmental factors on the alternation of the different Synechococcus groups were also elucidated. PE-rich SYN was detected in three surveys, whereas PC-rich SYN was detected in May and August, but not in November. The highest abundances of PE-rich SYN and PC-rich SYN were recorded in August and May, with mean values of 74.17×103 and 189.92×103 cells m L-1, respectively. From May to November, the relative abundance of PE-rich SYN increased, whereas that of PC-rich SYN declined. PE-rich and PC-rich SYN presented similar horizontal distributions with high abundance in the southern estuary in May, and in the western estuary in August. The abundances of PE-rich and PC-rich SYN were high at 27–32℃and salinity of 10–20. PC-rich SYN was not detected at < 24℃, and PC:PE-rich SYN decreased in abundance with salinity increase. When less than 20 mg L-1, suspended particulate matter(SPM) was helpful for Synechococcus growth. PE-rich SYN decreased in abundance when the concentration of dissolved inorganic nitrogen increased in May and November, and the concentration of phosphate increased in November. However, PC-rich SYN abundance and nutrients showed no correlation. Principal component analysis and regression analysis indicated that PE-rich SYN significantly correlated with the principal components that were affected by environmental factors.
文摘The effects of biochar on methane emissions from soils are well understood.However,biochar effects on methane production from livestock have received less attention.In this study,a biochar-mineral supplement for livestock was developed by pyrolyzing a mixture of wheat straw,aluminosilicates,iron sulfate,and zinc oxide at 600℃.The supplement was then activated using peracetic and propionic acids,and potassium nitrate.The activated biochar-mineral supplement was characterized using analytical techniques.A high surface area,a high concentration of oxygencontaining functional groups,and a high concentration of free radicals,associated with O and Fe unpaired electrons,assisted the supplement with catalysing the oxidation of methane.Microstructural analysis of the supplement suggested the formation of organo-mineral phases,rich in C,O,Fe,Si,Al,K and Ca,indicating that the biochar reacted with mineral additives to preserve them.To assess the potential of the supplement to reduce methane produced form livestock,an in vitro batch culture incubation was conducted(n=3)with rumen fluid sourced from Holstein–Friesian steers.The supplement was incubated at inclusion rates of 0%(control),1.5%,4.0%and 6.0%of dry matter(DM),with a Rhodes grass hay substrate.Compared to the control,the supplement reduced cumulative gas production by 10.1%and 12.7%and methane production by 19.03%and 29.32%after 48 h when included at 4.0%and 6.0%DM(P<0.05),respectively,without causing any detrimental impacts on fermentation parameters.The supplement assisted with reducing the concentration of dissolved mineral nutrients,such as P and Mg,when included at 4.0%and 6.0%DM(P<0.05).
