Water samples containing dissolved aluminum were collected from the Yellow and East China Seas in Octo- ber-November 2000. The average concentrations of dissolved Al in the Yellow Sea (YS) and East China Sea (ECS) wer...Water samples containing dissolved aluminum were collected from the Yellow and East China Seas in Octo- ber-November 2000. The average concentrations of dissolved Al in the Yellow Sea (YS) and East China Sea (ECS) were 0.042 and 0.056 μmolL-1, respectively. The concentration of dissolved aluminum decreased gradually across the continental shelf. The lower concentrations appeared in the YS cold water center and in the bottom layer at the shelf edge of the ECS, where they were 0.016 and 0.011 μmolL-1, respectively. The distribution of dissolved Al was controlled by physical mixing processes rather than biological up- take processes. The impact of different water masses along the PN transect was calculated based on the mass balance model. The results show that the impact of the Changjiang River was mainly concentrated on the coastal area and the top thermocline water on the ECS shelf, where the impact percentage decreased from 12.6% to 1.1% in the surface water, while the contribution of the Ku- roshio water was dominant on the ECS shelf in this survey, increasing from 77.6% to 97.8% along the PN transect from the Changjiang River Estuary to the Ryukyu Islands. It is concluded that aluminum can serve as a proper tracer for studying the impact of Changjiang terrestrial matter on the ECS shelf water.展开更多
Dissolved inorganic phosphorus （DIP ）,dissolved organic phosphorus （DOP ）,particulate inorganic phosphorus （P IP ） and particulate organic phosphorus （P OP ） in the Jiaozhou Bay （JZB） and its adjacent major ...Dissolved inorganic phosphorus （DIP ）,dissolved organic phosphorus （DOP ）,particulate inorganic phosphorus （P IP ） and particulate organic phosphorus （P OP ） in the Jiaozhou Bay （JZB） and its adjacent major rivers were analyzed during 2001–2003.DIP was the major form of dissolved phosphorus in JZB,representing 62%–83% of the total dissolved phosphorus （T DP ）,and the P IP concentration generally exceeded the P OP concentration.The concentrations of phosphorus were higher in the north than in the south of the bay,which were related to the fluvial input and water exchange rate.The dissolved phosphorus concentrations were higher in the autumn and spring than in the summer,while the seasonal variation of particulate phosphorus showed opposite pattern.The distribution of phosphorus is mainly affected by the growth of phytoplankton,desorption/adsorption of DIP from and to particulates,and anthropogenic activities.A preliminary phosphorus budget was established.In JZB,riverine input and water exchange flow between JZB and the Huanghai （Yellow） Sea are the major sources of phosphorus,followed by industrial and domestic waste transport,and then atmospheric deposition.Phosphorus burial efficiency is estimated to be 91%.About 52.2 × 10 6 mol/a of phosphorus were assimilated by phytoplankton,of which about 68% was recycled in the water column and sediment.展开更多
Temporal and spatial distribution of biogenic （BSi） and lithogenic （LSi） silica were studied in the Changjiang （Yangtze River） Estuary and its adjacent area. The annual average BSi and LSi concentrations were （...Temporal and spatial distribution of biogenic （BSi） and lithogenic （LSi） silica were studied in the Changjiang （Yangtze River） Estuary and its adjacent area. The annual average BSi and LSi concentrations were （1.714-1.79） #mol/L and （0.564-1.41） mmol/L, respectively. Both BSi and LSi were high ii~. tbe inshore ar- eas, where they received terrigenous discharge from the Changjiang, and decreased towards the offshore region. BSi and LSi were most abundant at the near bottom layer due to the high sedimentation rates and resuspension of sediment. Diatom blooms occurred in summer with high Chl a concentration in the sur- face layer, which induced that BSi in the surface layer during summer was obviously higher than that in the surface layer of other seasons. LSi concentration was maximal in autumn and spring and minimum in summer, associated with the seasonal variation of SPM values. Drifting investigation and mesocosm exper- iments were conducted during dinoflagellate bloom, aiming to understand the effect of nutrients on BSi by changing the phytoplankton composition. The results show that the low dissolved inorganic phosphorus concentration and high molar ratio of N/P （dissolved inorganic nitrogen vs. dissolved inorganic phospho- rus）, were the important factors for decreasing diatom biomass in the study area, and it would subsequently decrease the BSi concentration in aquatic ecosystem.展开更多
Water samples were collected in the coastal area of the Changjiang Estuary on four cruises from August 2002 to May 2003. The seasonal variations of dissolved inorganic arsenic (DIAs) distributions were analyzed. The r...Water samples were collected in the coastal area of the Changjiang Estuary on four cruises from August 2002 to May 2003. The seasonal variations of dissolved inorganic arsenic (DIAs) distributions were analyzed. The results showed that the distributions of DIAs were mainly influenced by the terrestrial input and the intrusion of the Kuroshio Subsurface Water (KSSW). The concentration of the total dissolved inorganic arsenic (TDIAs) decreased consecutively from winter to summer, while it increased in autumn. The distributions of TDIAs showed some relationships with salinity and suspended particulate matter (SPM). The relationships between DIAs speciation (including arsenite [As(Ⅲ)] and arsenate [As(Ⅴ)]), biological activity and the availabilities of the phosphate were investigated in the study area for the cruise August 2002. The ratio of As (Ⅲ)/TDIAs increased with the decrease of phosphate concentrations. In the bottom water, the As(Ⅲ)/TDIAs ratio decreased with the increasing of N/P. The concentration of TDIAs decreased 28.7% approximately after the occurrence of harmful algal blooms (HAB) because of the uptake of arsenate by algae. Further study is needed about the arsenic source/sink relationships in their vertical or horizontal profiles and the uptake mechanism during the occurrence of harmful algal blooms.展开更多
A sensitive solvent extraction method for the determination of nonamolar concentrations of silicate in natural waters is developed. According to the traditional aqueous silicate method, silicomolybdenum blue formed by...A sensitive solvent extraction method for the determination of nonamolar concentrations of silicate in natural waters is developed. According to the traditional aqueous silicate method, silicomolybdenum blue formed by the reaction between silicate and ammoni- um molydate and reduced by metol-sulfite reagent is extracted by methyl isobutyl ketone. The absorbance can be enhanced substantially up to 10-folds. The detection limit of silicate is 8 nmol/dm^3 , which is one tenth smaller than the traditional method, with the precision of 4.0% at a silicate level of 50 nmol/dm^3 and 3.2% at a silicate level of 6 μmol/dm^3. Comparing the calibration curves in the distilled water and seawater, it can be seen that the salt effect also exists in the extraction method. However, the salt effect is a linear function of the salinity and can be corrected by simple calibration. The proposed method is successfully applied to the determination of silicate in natural waters. Natural concentrations of arsenate, arsenite and phosphate cause negligible interference.展开更多
Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were app...Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were applied for the measurement of dissolved inorganic phosphorus （DIP） and total dissolved phosphorus （TDP） in more than 840 water samples collected between 2003 and 2005, including seawater （the Huanghai Sea, the East China Sea, and the northern South China Sea）, water from rivers and estuaries （the Changjiang, the Huanghe, and the major rivers emptying into the Jiaozhou Bay）, groundwater （in the drainage basin surrounding the Jiaozhou Bay）, rain-water, and aquaculture water samples. The MAGIC method allows the investigation of phosphorus distributions and cycling for systems in which DIP is below the detection limits of conventional methods. Comparison between the two methods demonstrated that the concentrations obtained with both methods were significantly correlated. The differences of DIP and TDP concentrations measured with the two methods were higher when the concentrations of DIP and TDP were lower, implying the lower reproducibility at low concentrations. The concentration differences increase with the increase in the proportion of DOP in TDP, which indicates that the discrepancy of DIP concentrations measured with the two methods increases when the DOP concentration is high. The discrepancies indicated that the composition of P compounds differs depending on sample sources and water type; it would be useful to infer the presence of different phosphorus compound pools from differences between the two methods. This study indicates the potential presence of a pool of alkaline-labile compounds for samples from rainwater and rivers and estuaries surrounding the Jiaozhou Bay; the potential presence of acid-labile compounds that were adsorbed by Mg（OH）2 for samples from the Changjiang Estuary, Huanghai Sea, East China Sea, and groundwater; the potential presence of a substantial pool of acid-labile compounds that were not adsorbed by Mg（OH）2 for samples from the Huanghe Estuary, aquaculture water, the East China Sea algal bloom water, and the northern South China Sea.展开更多
Many recent studies have investigated the nutrient-type profiles of dissolved aluminum(Al) in the ocean.Significant scavenging of dissolved Al can occur during phytoplankton blooms,but the mechanism remains unclear.Th...Many recent studies have investigated the nutrient-type profiles of dissolved aluminum(Al) in the ocean.Significant scavenging of dissolved Al can occur during phytoplankton blooms,but the mechanism remains unclear.The distribution of dissolved Al in the southern Yellow Sea(SYS) was investigated in winter and spring 2009.Following measurements at grid stations during the spring sampling cruise,two drifting anchor surveys of more than 100 h were conducted to trace the variation of dissolved Al concentration during the spring phytoplankton bloom(SPB).The concentration of dissolved Al in the SYS decreased from 40 nmol/L in February to 30 nmol/L in March and 10-20 nmol/L in April,while the concentration of Chl a increased from < 2 μg/L in March to > 4 μg/L in April.The concentration of dissolved Al in the SYS decreased significantly with the development of the phytoplankton bloom,which indicated biological scavenging of dissolved Al from water column.The proportion of dissolved Al scavenged from water column by different phytoplankton species differed at the two drifting stations,with greater removal efficiency demonstrated by diatoms than dinoflagellates.Phytoplankton samples collected from the Chl a maximum layer were washed with trace metal clean reagent(oxalate-EDTA-citrate,abbreviate as oxalate solution,Tovar-Sanchez et al.,2003) to enable the surface-scavenged(extracellular) and intracellular Al pools associated with phytoplankton to be differentiated.Thirty-nine to ninetysix percent of the total Al was found to be existed in the interior pools,which indicated that biological absorption was the important way to scavenge dissolved Al during phytoplankton blooms in the SYS.展开更多
基金funded by the National Basic Research Program of China(No.2006CB400601)Natural Science Foundation of China(No.40606028).
文摘Water samples containing dissolved aluminum were collected from the Yellow and East China Seas in Octo- ber-November 2000. The average concentrations of dissolved Al in the Yellow Sea (YS) and East China Sea (ECS) were 0.042 and 0.056 μmolL-1, respectively. The concentration of dissolved aluminum decreased gradually across the continental shelf. The lower concentrations appeared in the YS cold water center and in the bottom layer at the shelf edge of the ECS, where they were 0.016 and 0.011 μmolL-1, respectively. The distribution of dissolved Al was controlled by physical mixing processes rather than biological up- take processes. The impact of different water masses along the PN transect was calculated based on the mass balance model. The results show that the impact of the Changjiang River was mainly concentrated on the coastal area and the top thermocline water on the ECS shelf, where the impact percentage decreased from 12.6% to 1.1% in the surface water, while the contribution of the Ku- roshio water was dominant on the ECS shelf in this survey, increasing from 77.6% to 97.8% along the PN transect from the Changjiang River Estuary to the Ryukyu Islands. It is concluded that aluminum can serve as a proper tracer for studying the impact of Changjiang terrestrial matter on the ECS shelf water.
基金The National Basic Research Program of China under contract No. 2010CB428901the National Natural Science Foundation of China under contract Nos 40206017 and 40925017Basic Research Program of Science and Technology of the Ministry of Education under contract No. 108081
文摘Dissolved inorganic phosphorus （DIP ）,dissolved organic phosphorus （DOP ）,particulate inorganic phosphorus （P IP ） and particulate organic phosphorus （P OP ） in the Jiaozhou Bay （JZB） and its adjacent major rivers were analyzed during 2001–2003.DIP was the major form of dissolved phosphorus in JZB,representing 62%–83% of the total dissolved phosphorus （T DP ）,and the P IP concentration generally exceeded the P OP concentration.The concentrations of phosphorus were higher in the north than in the south of the bay,which were related to the fluvial input and water exchange rate.The dissolved phosphorus concentrations were higher in the autumn and spring than in the summer,while the seasonal variation of particulate phosphorus showed opposite pattern.The distribution of phosphorus is mainly affected by the growth of phytoplankton,desorption/adsorption of DIP from and to particulates,and anthropogenic activities.A preliminary phosphorus budget was established.In JZB,riverine input and water exchange flow between JZB and the Huanghai （Yellow） Sea are the major sources of phosphorus,followed by industrial and domestic waste transport,and then atmospheric deposition.Phosphorus burial efficiency is estimated to be 91%.About 52.2 × 10 6 mol/a of phosphorus were assimilated by phytoplankton,of which about 68% was recycled in the water column and sediment.
基金The National Natural Sciences Foundation of China under contract Nos 40925017 and 40876054the Ministry of Science&Technology of P.R.China under contract Nos 2011CB409802 and 2001CB409703
文摘Temporal and spatial distribution of biogenic （BSi） and lithogenic （LSi） silica were studied in the Changjiang （Yangtze River） Estuary and its adjacent area. The annual average BSi and LSi concentrations were （1.714-1.79） #mol/L and （0.564-1.41） mmol/L, respectively. Both BSi and LSi were high ii~. tbe inshore ar- eas, where they received terrigenous discharge from the Changjiang, and decreased towards the offshore region. BSi and LSi were most abundant at the near bottom layer due to the high sedimentation rates and resuspension of sediment. Diatom blooms occurred in summer with high Chl a concentration in the sur- face layer, which induced that BSi in the surface layer during summer was obviously higher than that in the surface layer of other seasons. LSi concentration was maximal in autumn and spring and minimum in summer, associated with the seasonal variation of SPM values. Drifting investigation and mesocosm exper- iments were conducted during dinoflagellate bloom, aiming to understand the effect of nutrients on BSi by changing the phytoplankton composition. The results show that the low dissolved inorganic phosphorus concentration and high molar ratio of N/P （dissolved inorganic nitrogen vs. dissolved inorganic phospho- rus）, were the important factors for decreasing diatom biomass in the study area, and it would subsequently decrease the BSi concentration in aquatic ecosystem.
基金This research was supported by the National Basic Research Program of China （Nos. 2001CB409703 and G1999043705） the National Natural Science Foundation of China （Nos. 40036010 and 40206017）.
文摘Water samples were collected in the coastal area of the Changjiang Estuary on four cruises from August 2002 to May 2003. The seasonal variations of dissolved inorganic arsenic (DIAs) distributions were analyzed. The results showed that the distributions of DIAs were mainly influenced by the terrestrial input and the intrusion of the Kuroshio Subsurface Water (KSSW). The concentration of the total dissolved inorganic arsenic (TDIAs) decreased consecutively from winter to summer, while it increased in autumn. The distributions of TDIAs showed some relationships with salinity and suspended particulate matter (SPM). The relationships between DIAs speciation (including arsenite [As(Ⅲ)] and arsenate [As(Ⅴ)]), biological activity and the availabilities of the phosphate were investigated in the study area for the cruise August 2002. The ratio of As (Ⅲ)/TDIAs increased with the decrease of phosphate concentrations. In the bottom water, the As(Ⅲ)/TDIAs ratio decreased with the increasing of N/P. The concentration of TDIAs decreased 28.7% approximately after the occurrence of harmful algal blooms (HAB) because of the uptake of arsenate by algae. Further study is needed about the arsenic source/sink relationships in their vertical or horizontal profiles and the uptake mechanism during the occurrence of harmful algal blooms.
基金The National Science Foundation of China under contract No.40606028the Special Fund from the National Key Basic Research Program of China under contract No.2006CB400601.
文摘A sensitive solvent extraction method for the determination of nonamolar concentrations of silicate in natural waters is developed. According to the traditional aqueous silicate method, silicomolybdenum blue formed by the reaction between silicate and ammoni- um molydate and reduced by metol-sulfite reagent is extracted by methyl isobutyl ketone. The absorbance can be enhanced substantially up to 10-folds. The detection limit of silicate is 8 nmol/dm^3 , which is one tenth smaller than the traditional method, with the precision of 4.0% at a silicate level of 50 nmol/dm^3 and 3.2% at a silicate level of 6 μmol/dm^3. Comparing the calibration curves in the distilled water and seawater, it can be seen that the salt effect also exists in the extraction method. However, the salt effect is a linear function of the salinity and can be corrected by simple calibration. The proposed method is successfully applied to the determination of silicate in natural waters. Natural concentrations of arsenate, arsenite and phosphate cause negligible interference.
基金The National Natural Science Foundation of China under contract Nos 40876054 and 40925017the Science and Technology Key Program of the Ministry of Education under contract Nos NCET-05-0593 and 108081the Special Funds from National Key Basic Research Program under contract Nos 2006CB400602 and 2007DFB20380
文摘Phosphorus （P） is an essential nutrient utilized by all organisms for energy transport and growth. Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation （MAGIC） procedures were applied for the measurement of dissolved inorganic phosphorus （DIP） and total dissolved phosphorus （TDP） in more than 840 water samples collected between 2003 and 2005, including seawater （the Huanghai Sea, the East China Sea, and the northern South China Sea）, water from rivers and estuaries （the Changjiang, the Huanghe, and the major rivers emptying into the Jiaozhou Bay）, groundwater （in the drainage basin surrounding the Jiaozhou Bay）, rain-water, and aquaculture water samples. The MAGIC method allows the investigation of phosphorus distributions and cycling for systems in which DIP is below the detection limits of conventional methods. Comparison between the two methods demonstrated that the concentrations obtained with both methods were significantly correlated. The differences of DIP and TDP concentrations measured with the two methods were higher when the concentrations of DIP and TDP were lower, implying the lower reproducibility at low concentrations. The concentration differences increase with the increase in the proportion of DOP in TDP, which indicates that the discrepancy of DIP concentrations measured with the two methods increases when the DOP concentration is high. The discrepancies indicated that the composition of P compounds differs depending on sample sources and water type; it would be useful to infer the presence of different phosphorus compound pools from differences between the two methods. This study indicates the potential presence of a pool of alkaline-labile compounds for samples from rainwater and rivers and estuaries surrounding the Jiaozhou Bay; the potential presence of acid-labile compounds that were adsorbed by Mg（OH）2 for samples from the Changjiang Estuary, Huanghai Sea, East China Sea, and groundwater; the potential presence of a substantial pool of acid-labile compounds that were not adsorbed by Mg（OH）2 for samples from the Huanghe Estuary, aquaculture water, the East China Sea algal bloom water, and the northern South China Sea.
基金supported by the National Basic Research Program of Science and Technology of China(2011CB409801)the National Natural Science Foundation of China(41176096)
文摘Many recent studies have investigated the nutrient-type profiles of dissolved aluminum(Al) in the ocean.Significant scavenging of dissolved Al can occur during phytoplankton blooms,but the mechanism remains unclear.The distribution of dissolved Al in the southern Yellow Sea(SYS) was investigated in winter and spring 2009.Following measurements at grid stations during the spring sampling cruise,two drifting anchor surveys of more than 100 h were conducted to trace the variation of dissolved Al concentration during the spring phytoplankton bloom(SPB).The concentration of dissolved Al in the SYS decreased from 40 nmol/L in February to 30 nmol/L in March and 10-20 nmol/L in April,while the concentration of Chl a increased from < 2 μg/L in March to > 4 μg/L in April.The concentration of dissolved Al in the SYS decreased significantly with the development of the phytoplankton bloom,which indicated biological scavenging of dissolved Al from water column.The proportion of dissolved Al scavenged from water column by different phytoplankton species differed at the two drifting stations,with greater removal efficiency demonstrated by diatoms than dinoflagellates.Phytoplankton samples collected from the Chl a maximum layer were washed with trace metal clean reagent(oxalate-EDTA-citrate,abbreviate as oxalate solution,Tovar-Sanchez et al.,2003) to enable the surface-scavenged(extracellular) and intracellular Al pools associated with phytoplankton to be differentiated.Thirty-nine to ninetysix percent of the total Al was found to be existed in the interior pools,which indicated that biological absorption was the important way to scavenge dissolved Al during phytoplankton blooms in the SYS.
