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1.
Concentrations of dissolved and particulate organic carbon (DOC and POC) were documented in 1996–1997 at 4 different trophic
state stations in Donghu Lake, a typical shallow eutrophic lake along the Changjiang River's middle reaches. The mean concentrations
of DOC were 15.11±3.26, 15.19±4.24, 14.27±3.43, and 13.31±3.30 mg/L in Station I, II, III, and IV, respectively. The DOC concentrations
of the studied area were very similar to that in other lakes along the Changjiang River's middle reaches. The POC mean of
the whole lake was 5.01 mg/L due to the large amount of organic detritus of both allochthonous and autochthonous origin. Significant
linear relationship was found between POC and chlorophyll a at all 4 stations, which presumably reflect that phytoplankton,
its exudates and its metabolic products were the main contributors to the POC pool in the water column. The slope of such
linear relationship at Station IV was significantly steeper than that at Station I, II and III. In addition, the DOC/POC ratios
(mean value: 4.40) indicated that the organic detritus was the most important component of the particulate organic matter;
in other works, next to organic detritus, phytoplankton dominated the particulate organic matter in Donghu Lake.
Project 39770146, 39430101 supported by NSFC and the State Key Laboratory of Freshwater Ecology and Biotechnology, affiliated
to the Institute of Hydrobiology, Chinese Academy of Sciences. 相似文献
2.
Preliminary study on the dissolved and colloidal organic carbon in the Zhujiang River estuary 总被引：3，自引：0，他引：3
ＩＮＴＲＯＤＵＣＴＩＯＮＥｓｔｕａｒｉｅｓｃｏｍｐｒｉｓｅａｍａｊｏｒｂｉｏｇｅｏｃｈｅｍｉｃａｌｉｎｔｅｒｆａｃｅｃｏｎｎｅｃｔｉｎｇｔｈｅｌａｎｄａｎｄｔｈｅｓｅａ (Ｍａｎ ｔｏｕｒａ,1 987) .Ｔｈｅｂｅｈａｖｉｏｒａｎｄｆａｔｅｏｆａｐａｒｔｉｃｕｌａｒｒｉｖｅｒ ｂｏｒｎｅｓｕｂｓｔａｎｃｅｉｎｔｒｏｄｕｃｅｄｉｎｔｏａｎｅｓｔｕａｒｙｉｓｄｅｔｅｒｍｉｎｅｄｔｏａｌａｒｇｅｅｘｔｅｎｔｂｙｔｈｅｂｉｏｇｅｏｃｈｅｍｉｃａｌｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｓｕｂｓｔａｎｃｅａｓｗｅｌｌａｓｐ… 相似文献
3.
The effects of estuarine processes on the fluxes of inorganic and organic carbon in the Yellow River estuary 总被引：1，自引：0，他引：1
Riverine carbon flux is an important component of the global carbon cycle. The spatial and temporal variations of organic
and inorganic carbon were examined during both dry and wet seasons in the Yellow River estuary. Concentrations of dissolved
organic carbon (DOC) and dissolved inorganic carbon (DIC) in the Yellow River during dry seasons were higher than those during
wet seasons. The effective concentrations of DOC (CDOC*) were higher than the observed DOC at zero salinity. This input of DOC in the Yellow River estuary was due to sediment desorption
processes in low salinity regions. In contrast to DOC, the effective concentrations of DIC were 10% lower than the DIC measured
at freshwater end, and the loss of DIC was caused by CaCO3 precipitation in low salinity region. Particulate organic carbon (POC) and particulate inorganic carbon (PIC) contents of
the particles stabilized to constant values (0.5%±0.05% and 1.8%±0.2%, respectively) within the turbidity maximum zone (TMZ)
and showed no noticeable seasonal variations. A rapid drop of PIC and rise of POC occurred simultaneously outside the TMZ
due to an intense dilution of riverine inorganic-rich particles being transported into a pool of aquatic organic-poor particles
outside the TMZ. Annually, the Yellow River transported 6.95×105 t of DIC, 0.64×105 t of DOC, 78.58×105 t of PIC and 2.29×105 t of POC to the sea. 相似文献
4.
234Th-238u disequilibria were applied to examine the particle dynamics in the euphotic zone of the central South China Sea during the spring 2002 cruise. The particulate organic carbon (POC), 234Th (including both dissolved and particulate) and 238U in the water column at three stations were determined. The profiles of 234Th/238U activity ratio at the three stations all showed consistent 234Th deficit as compared to 238U in the upper 100 m water column. Based on the profiles of the dissolved and particulate 234Th and a steady state box model, the dissolved 234Th scavenging rates, the particulate 234Th removal rates and their resident times were quantified. It was found that the POC downward export fluxes out of the upper 100 m euphotic zone ranged from 9.40 to 14.78 mmol.m-2.d-1. The results from this study provide new information for our understanding of carbon biogeochemical cycle in the South China Sea. 相似文献
5.
During the Second Chinese National Arctic Expedition (CHINARE) from July to September 2003, depth profiles of dissolved and particulate 234Th in upper water columns were collected at two stations of BR03 and BR24 in the Bering Sea. 234Th was sampled by using a traditional Fe(OH)3 co-precipitation technique, which is a reliable approach to 234Th measurement. We observed 234Th excess at station BR03 below the euphotic zone, which was possibly due to the intensive remineralization of particulate matter. Particulate organic carbon (POC) export fluxes were estimated from a one-dimensional irreversible steady state model of 234Th fluxes together with measurements of the POC/234Th ratio on the suspended particles. The POC export fluxes from the euphotic zone were 11.66 and 11.69 mmol C m-2 d-1 at BR03 and BR24 stations,respectively. The ratios of POC fluxes to primary production at the two stations were about 0.5 and 0.59, respectively, probably due to the presence of large phytoplankton (in particular diatoms). 相似文献
6.
Effects of land management practices on labile organic carbon fractions in rice cultivation 总被引：1，自引：1，他引：0
SHAO Jing＇an LI Yangbing WEI Chaofu XIE Deti 《中国地理科学(英文版)》2009,19(3):241-248
A research trial with four land management practices, i.e., traditional tillage-fallow (TTF), traditional tillage-wheat (TTW),
conservation tillage-fallow (CTF) and conservation tillage-wheat (CTW), was sampled in the 15th year after its establishment
to assess the effects of different management practices on labile organic carbon fractions (LOCFs), such as easily oxidizable
organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC) and microbial biomass carbon (MBC)
in a typical paddy soil, Chongqing, Southwest China. The results indicated that LOCFs were significantly influenced by the
combination of no-tillage, ridge culture and crop rotation. And, different combination patterns showed different effectiveness
on soil LOCFs. The effects of no-tillage, ridge culture and wheat cultivation on EOC, DOC, POC and MBC mainly happened at
0–10cm. At this depth, soil under CTW had higher EOC, DOC, POC and MBC contents, compared to TTF, TTW and CTF, respectively.
Moreover, the contents of LOCFs for different practices generally decreased when the soil depth increased. Our findings suggest
that the paddy soil in Southwest China could be managed to concentrate greater quantities of EOC, DOC, POC and MBC.
Foundation item: Under the auspices of Key Project of National Natural Science Foundation of China (No. 40231016) 相似文献
7.
A one-year field study was conducted to determine the conversion ratio of phytoplankton biomass carbon (Phyto-C) to chlorophyll-a (Chl-a) in Jiaozhou Bay, China. We measured suspended particulate organic carbon (POC) and phytoplankton Chl-a samples collected in surface water monthly from March 2005 to February 2006. The temporal and spatial variations of Chl-a and POC concentrations were observed in the bay. Based on the field measurements, a linear regression model II was used to
generate the conversion ratio of Phyto-C to Chl-a. In most cases, a good linear correlation was found between the observed POC and Chl-a concentrations, and the calculated conversion ratios ranged from 26 to 250 with a mean value of 56 μg μg−1. The conversion ratio in the fall was higher than that in the winter and spring months, and had the lowest values in the
summer. The ratios also exhibited spatial variations, generally with low values in the near shore regions and relatively high
values in offshore waters. Our study suggests that temperature was likely to be the main factor influencing the observed seasonal
variations of conversion ratios while nutrient supply and light penetration played important roles in controlling the spatial
variations. 相似文献
8.
Size-fractionated 210Po and 210Pb, in the size fractions >0.4 μm, >2 μm and >10 μm, were examined to determine the seasonal variability of particulate fluxes
in Xiamen Bay. Good correlations between 210Po and particulate organic carbon (POC) or non-Particulate Organic Matter (nPOM) suggested that 210Po can be used to trace the export fluxes of POC and nPOM. Both steady-state (SS) model and nSS model were used to evaluate
fluxes of size-fractionated 210Po, results showed that nSS model was better than the SS model in coastal areas. Based on the nSS model, size-fractionated
POC fluxes decreased with increasing particle size. For the particle size studied, maximum POC fluxes occurred in autumn,
followed by spring, winter, and summer. Fluxes of nPOM were an order of magnitude higher than the corresponding size-fractionated
POC fluxes. Differences between size-fractionated nPOM fluxes indicated that hydrodynamic conditions were the main factor
regulating transportation of particulate out of the inner Bay. In winter most particulates, including >10 μm particles, were
transported under the strongest hydrodynamic conditions. In contrast, only a fraction of the <2 μm particulates were transported
from the inner Bay in spring. This study suggested that 210Po is a powerful tracer of seasonal particulate export in coastal seas. 相似文献
9.
The effects of using different types of glass fiber filters (GF/F, GF/C) and of sample treatments evaluated. Studies on the variation of suspended matter (SM) and particulate organic carbon (POC) showed that: 1) the transversal and day to night variations are important and must be taken into account in order to get a corrcet river flux; 2) no regular seasonal variations of SM and POC observed, as they are controlled essentially by the climatological, hydrologic, physiochernical, biological, and geological conditions of the drainage area. 相似文献
10.
A field observation was carried out in the Changjiang （Yangtze） River Estuary from May 19 to 26, 2003. A total of 29 stations, including 2 anchored stations, were occupied through almost the whole salinity gradient. Based on the observation data, biogeochemistry of chemical oxygen demand （COD） was examined. Spatial distribution pattern of COD shows that it decreased downstream. The COD concentration varied generally within a narrow range of 1.24-1.60 mg/L in the zone around the river mouth, beyond which it decreased rapidly to 0.20 mg/L. In the mixed water zone, the fluctuation in COD was smaller at 2 m above the bottom layer than at the surface layer in 48 h. In the seawater zone, the 48-h fluctuation at the surface was the largest, followed by that of 5 m below the surface and 2 m above the bottom layers in a range of from 2.50 to 0.55 mg/L. Freshwater discharge was the dominant source of COD in the estuary. The average COD beyond the river mouth was 2.7 mg/L, which accorded with the Chinese seawater quality Grade I. Relationships between dissolved oxygen and biogeochemical parameters such as suspended particulate matter, dissolved organic matter and chlorophyll-a were also discussed. 相似文献
11.
Chemical characterization and composition of dissolved organic matter in Jiaozhou Bay 总被引：1，自引：0，他引：1
Biologically utilizable dissolved organic compounds, including dissolved organic carbon (DOC), dissolved carbohydrates (DCHO)
and dissolved free amino acids (DFAA) were analyzed in filtered surface seawater samples collected at 19 stations in Jiaozhou
Bay, China, on June 3, 2007. In these samples, concentrations of DOC, dissolved free carbohydrates (DFCHO), dissolved combined
carbohydrates (DCCHO), total dissolved carbohydrates (TDCHO) and total dissolved free amino acids (TDFAA) ranged from 141.7
to 191.1 μmol C/L, 1.98 to 18.18 μmol C/L, 5.04 to 24.90 μmol C/L, 14.52 to 30.36 μmol C/L, and 1.83 to 11.89 μmol C/L, respectively.
As a major component of the dissolved carbohydrates, the concentrations of DCCHO were about three times higher than those
of DFCHO. Three major constituents of the DFAA were threonine (23.0±5.7 mol%), glutamic acid (16.6±3.2 mol%) and arginine
(9.1±3.3 mol%). Based on the composition of DFAA, a molar C:N ratio of 3.60±0.75 in DFAA was derived, indicating longer carbon
chains in the amino acids. DCCHO (8.1%) was the most abundant fraction of DOM in most samples, followed by DFCHO (4.8%) and
TDFAA (2.7%). These DOM concentrations displayed a decreasing trend from the coast to the central region. Significant correlations
were found between the DCCHO and DFCHO concentrations (r=-0.724, n=19, P<0.001) and the DCCHO and TDCHO concentrations (r=0.506, n=19, P=0.027). 相似文献
12.
Variations of the suspended matter and the particulate organic carbon in the entry of the Gironde Estuary,France 总被引：1，自引：0，他引：1
The effects of using different types of glass fiber filters (GF/F, GF/C) and of sample treatments were evaluated. Studies
on the variation of suspended matter (SM) and particulate organic carbon (POC) showed that: 1) the transversal and day to
night variations are important and must be taken into account in order to get a correct river flux; 2) no regular seasonal
variations of SM and POC were observed, as they are controlled essentially by the climatological, hydrologic, physiochemical,
biological, and geological conditions of the drainage area.
Contribution No 2246 from the Institute of Oceanology, Chinese Academy of Sciences. 相似文献
13.
徐闻珊瑚礁保护区营养盐时空分布特征 总被引：2，自引：1，他引：1
2006年8月(夏季)、2006年11月(秋季)、2007年2月(冬季)和2007年4月(春季)在徐闻珊瑚礁自然保护区灯楼角至流沙湾近岸海域调查徐闻珊瑚礁保护区的营养盐变化及空间分布特征。结果表明:徐闻珊瑚礁保护区水域溶解态无机氮以NO3--N为主,其含量超过总溶解无机氮的50%;各站点NO2--N含量相对较低,冬季NO3--N和NH4+-N含量均高于其它季节;无机磷含量在0mg/L～0.030mg/L之间变化;活性硅含量表现为夏秋季节高、冬春季节低;表层水体硝酸盐氮/无机磷原子比值(N/P)夏季较低,不存在无机磷受限情况,而冬季N/P整体较高,此时水体主要受无机磷限制。 相似文献
14.
^234Th-^238U disequilibria were applied to examine the particle dynamics in the euphotic zone of the central South China Sea during the spring 2002 cruise. The particulate organic carbon （POC）, ^234Th （including both dissolved and particulate） and ^238U in the water column at three stations were determined. The profiles of ^234Th/^238U activity ratio at the three stations all showed consistent ^234Th deficit as compared to ^238U in the upper 100 m water column. Based on the profiles of the dissolved and particulate ^234Th and a steady state box model, the dissolved ^234Th scavenging rates, the particulate ^234Th removal rates and their resident times were quantified. It was found that the POC downward export fluxes out of the upper 100 m euphotic zone ranged from 9.40 to 14.78 mmol·m^-2·d^-1. The results from this study provide new information for our understanding of carbon biogeochemical cycle in the South China Sea. 相似文献
15.
ImODUrnONTheobjeCtiveoftheJointGobaldrinFluxStudy(JGoFS)istogainunder-standingoftheglobalbiogeochdricalCycling(ofcarbonandotherbiogenicelemetS)whichplaysaTnaorroleininIlUencintheworkldrite.OnofitSessentinlcomPonentSistocharaCtedrithernarineprharybiomassproductionandthefixationofCO=bytheocan.AmngtheproassesaffedgVCrthalfluxofcarbontotheinterioroftheoean,thebiologhalproass,thesocalled"biologhalpUmP,',isthemostirnPortantone.bologicalmodellingisamehodtorelateleVeIs,distributionandfluC… 相似文献
16.
CHENG Yan REN Jingling LI Dandan LIU Sumei ZHANG Jing 《中国海洋大学学报(英文版)》2006,5(3):243-250
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 Water （KSSW）. The concentration of the total dissolved the terrestrial input and the intrusion of the Kuroshio Subsurface 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. 相似文献
17.
Precipitation is the dominant factor that controls vegetation growth and land-use practices in the arid and semiarid Mongolian Plateau(MP), so the spatiotemporal heterogeneity of precipitation change has been an important scientific question in the region. This study investigated the spatiotemporal characteristics of annual and seasonal precipitation across the entire MP based on monthly precipitation data from 136 meteorological stations during 1961–2014 by using a modified Mann–Kendall test, Sen's slope, Morlet Wavelet Transform, and geostatistical methods. Results show the following: 1) Annual precipitation decreased slightly from 1961 to 2014.Stations with positive and negative trends were 41.9%and 58.1%, respectively. Significant positive trends were mainly in the southwestern and northeastern regions of the plateau, whereas significant negative trends were in the northern and southeastern regions.2) Precipitation decreased at rates of-5.65 and-0.41 mm/decade in summer and autumn, respectively, but increased at 1.91 and 0.51 mm/decade in spring and winter. The contribution of spring and winter precipitation to the annual amount increased significantly, but that of summer precipitation decreased significantly. 3) A large majority of stations(80.2%) showed decreasing trends in summer,whereas 89.7% and 83.1% of stations showed increasing trends in spring and winter. The spatial distribution of trend magnitude in seasonal precipitation amount was strongly heterogeneous. 4)By climatic zones, precipitation increased in humid and arid zones, but decreased in a semiarid zone. On the whole, the MP experienced a drying trend, with significant regional differentiation and seasonal variations. 相似文献
18.
Seasonal variations of riverine organic carbon contents in Makou and Hekou gauge stations of the Zhujiang River, China 总被引：1，自引：1，他引：0
Quan-zhou Gao Cheng-de Shen Yan-min Sun Wei-xi Yi Jia-mo Fu Guo-ying Sheng 《中国地理科学(英文版)》2000,10(4):302-308
Water samples were collected and analyzed in high water season (July 1997) and in middle water season (October, 1997) from
two main lower reach gauge stations of the Zhujiang (Pearl) River, namely Hekou and Makou, respectively. Content of particulate
organic carbon is always higher than that of dissolved organic carbon in both seasons, which is obviously different from the
global average pattern, i.e. dissolved organic carbon is the dominant component of the transported riverine organic carbon.
The content of dissolved and particulate organic carbon changes with the water levels in a direct ratio. The percentage of
organic carbon in total suspended substance changes with the content of total suspended substance in an inverse ratio. The
more intense is the soil erosion in the drainage, the more concentrated is the riverine organic carbon in the river. The contribution
of autochthonous organic carbon is large in high water season than in middle water season.
Fundation item: This project was supported financially by the National Natural Science Foundation of China (No. 49901002),
the key funds of resources and eco-environmental research of the CAS (No. KZ952-J1-402), a funds of the state key laboratory
of organic geochemistry, and Guangdong Province Science Funds (No. 984131).
Biography: Gao Quan-zhou (1965 —), male, a native of Anhui Province, associate professor. His research interests are geomorphology
and Quaternary geochemistry. 相似文献
19.
ImODUonONGrowingconcemovertheprobboofobnoxiouswaterbloornspromPtedagreatdealofresearchintothebiologyofblue-grmalgae(Reynolds&Walsby,l975,Reynothe,l984).PreviousstudiesonMimptiSwereaimedatitSphySinlogicalcharaCteristirsindudinggroWthandbuoyancyraegnolds,l975),0Vendteringandphotosynthesisfea-turesffokamuraetal.,l984,Takamura,l985),nutrientdemandsoprlofTetal.,l952,0kado&Sudo,l979).TherearerepoffethatMicropstiswasawidelydistributalspedesthatcouldeasilybloomWhenambientenvironrnentSweresuit… 相似文献
20.
A dynamic box model was applied to study the characteristics of biogeochemical cycling of PO_4-P,NO_3-N,AOU,POC and PON in the southern Taiwan Strait region based on field data of the"Minnan Taiwan Bank Fishing Ground Upwelling Ecosystem Study" during the period of Dec.1987-Nov.1988.According to the unique hydrological and topographical features of the region,six boxesand three layers were considered in the model.The variation rates and fluxes of elements induced by hor-izontal current,upwelling,by diffusion,sinking of particles and biogeochemical processes were estimatedrespectively.Results further confirmed that upwellings had important effects in this region.Thenearshore upwelling areas had net input fluxes of nutrients brought by upwelling water,also had high de-pletion rates of nutrients and production rates of particulate organic matter and dissolved oxygen.Theabnormal net production of nutrients in the middle layer(10-30m) indicated the important role of bacte-ria in this high production region.Th 相似文献