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1.
The process-oriented model Forest-DNDC describing biogeochemical cycling of C and N and GHGs （greenhouse gases） fluxes （CO2, NO and N2O） in forest ecosystems was applied to simulate carbon sequestration and GHGs emissions in Abies fabric forest of the Gongga Mountains at southeastern edge of the Tibetan Plateau. The results indicated that the simulated gross primary production （GPP） of Abies fabric forest was strongly affected by temperature. The annual total GPP was 24,245.3 kg C ha^-1 yr^-1 for 2005 and 26,318.8 kg C ha^-1 yr^-1 for 2006, respectively. The annual total net primary production （NPP） was 5,935.5 and 4,882.2 kg C ha^-1 yr^-1 for 2005 and 2006, and the annual total net ecosystem production （NEP） was 4,815.4 and 3,512.8 kg C ha^-1 yr^-1 for 2005 and 2006, respectively. The simulated seasonal variation in CO2 emissions generally followed the seasonal variations in temperature and precipitation. The annual total CO2 emissions were 3,109.0 and 4,821.0 kg C ha^-1 yr^-1 for 2005 and 2006, the simulated annual total N2O emissions from forest soil were 1.47 and 1.36 kg N ha^-1 yr^-1 for 2005 and 2006, and the annual total NO emissions were 0.09 and o.12 kg N ha^-1 yr^-1 for 2005 and 2006, respectively.  相似文献   

2.
Dissolved nutrients (NO 3 − , PO4 3−, SiO3 2−) and oxygen, chlorophyll- a, pH, and Eh were measured on board during a cruise in August 1988 in the Changjiang Estuary region. Heavy metals, organic matter and carbonate contents were analyzed in laboratory. The results show that geochemical processes in the Changjiang Estuary have dual filtration effect: on the one hand geochemical filtration effect, reflected by ferromanganese oxide flocculation and sedimentation, occurs near the turbidity maximum, and leads to enrichment of heavy metals in suspended matter and sediments; on the other hand biogeochemical filtration, reflected by nutrients consumption, organic matter and carbonate sedimentation and enrichment of trace elements in suspended matter, occurs outside the plume water front. The biogeochemical filtration affects the environmental conditions; the dissolved oxygen and pH increase, in surface water and decrease in bottom water. The biogeochemical filtration effect outside the plume front is more important than the geochemical filtration effect near the turbidity maximum.  相似文献   

3.
Rainwater samples were collected in series in Qianliyan Island (southern Yellow Sea) and Shengsi Archipelago (East China Sea) between May 2000 and May 2002, chemical analysis for pH values,concentrations of heavy metals (Cu, Pb, Zn and Cd) and nutrients (NH4^-, NO3^-, PO43^-, SiO32^-) were performed.Results indicate that concentrations of most of the heavy metals and nutrients in rainwater show clear seasonal variation, i.e. high level in winter and low level in summer. Regionally, concentrations are higher in the southern Yellow Sea than in the East China Sea, but the annual input of heavy metals into oceans by wet deposition is similar in both stations. However, the input of nutrients by wet deposition in the East China Sea is 2-3 times higher than that in the southern Yellow Sea. In individual, Pb and PO4^3- are input to the sea mainly by dry deposition; whereas Cu, Zn, Cd and N compounds are input dominantly by wet deposition, the N/P ratios in the rainwater from two stations are much higher than those in seawater, showing a significant impact of atmospheric wet deposition on marine production and biogeochemical circulation of nutrients in these sea regions.  相似文献   

4.
The sea fluxes of trace metals, POC, and settled material were studied in anoxic seawater, Saanich Inlet, B. C., Canada with sediment traps. This paper discusses the change of mass fluxes of sediment, trace metals and POC for various seasons and depths. The annual mean of settled material is 1.56 g.m−2.a−1, 84.6 mg. m−2.a−1 for POC, 60.0 mg. m−2.a−1 for Cu, 16.5 mg.m−2.a−1 for Pb, 189 mg.m−2.a−1 for Zn, 2.20 mg.m−2.a−1 for Cd, 699 mg.m−2.a−1 for Fe, 38.8 mg.m−2.a−1 for Co, and 84.6 mg.m−2.a−1 for Ni. The relations between the average fluxes of trace metals and POC, the fluxes of trace metals and settled matter, and the sea fluxes of trace metals and Fe are in linear progression. The resident times of elements as calculated from sea flux, are 1.1 a. for Cu, 0.014 a. for Pb, 0.50 a. for Zn, 3.8 a. for Cd, 0.16 a. for Fe, 0.39 a. for Co, and 1.14 a. for Ni. The order of resident times is as follows: Pb−Fe−Co−Zn−Cu−Ni−Cd. The metal resident times in Saanich Inlet are shorter than the values estimated for the open ocean. It illustrates that the biochemical processes in shallow Saanich Inlet are faster than those in the open ocean, and that debries of plankton and fecal pellets of zooplankton play an important role in vertical transport of organic carbons. Contribution No. 1650 from the Institute of Oceanology, Academia Sinica.  相似文献   

5.
Jiaozhou Bay data collected from May 1991 to February 1994, in 12 seasonal investigations, and provided the authors by the Ecological Station of Jiaozhou Bay, were analyzed to determine the spatiotemporal variations in temperature, light, nutrients (NO3^--N, NO2^--N, NH4^ -N, SIO3^2--Si, PO4^3--P), phytoplankton, and primary production in Jiaozhou Bay. The results indicated that only silicate correlated well in time and space with, and had important effects on, the characteristics, dynamic cycles and trends of, primary production in Jiaozhou Bay. The authors developed a corresponding dynamic model of primary production and silicate and water temperature. Eq. ( 1 ) of the model shows that the primary production variation is controlled by the nutrient Si and affected by water temperature; that the main factor controlling the primary production is Si; that water temperature affects the composition of the structure of phytoplankton assemblage; that the different populations of the phytoplankton assemblage occupy different ecological niches for C, the apparent ratio of conversion of silicate in seawater into phytoplankton biomas and D, the coefficient of water temperature‘s effect on phytoplankton biomass. The authors researched the silicon source of Jiaozhou Bay, the biogeochemical sediment process of the silicon, the phytoplankton predominant species and the phytoplankton structure. The authors considered silicate a limiting factor of primary production in Jiaozhou Bay, whose decreasing concentration of silicate from terrestrial source is supposedly due to dilution by current and uptake by phytoplankton; quantified the silicate assimilated by phytoplankton, the intrinsic ratio of conversion of silicon into phytoplankton biomass, the proportion of silicate uptaken by phytoplankton and diluted by current; and found that the primary production of the phytoplankton is determined by the quantity of the silicate assimilated by them. The phenomenon of apparently high plant-nutrient concentTations but low phytoplankton biomass in some waters is reasonably explained in this paper.  相似文献   

6.
^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   

7.
Two surveys were performed for determining bacteria biomass (BB), temperature, salinity, chlorophyll a (chl-a) and nutrient concentrations at 11 stations with three sampling depths in the high-incidence regions of red tide in the East China Sea (ECS) in the spring of 2006. Temperature and salinity increased from nearshore to offshore region and from high latitude to low latitude in the two cruises of 2006. BB were between 0.3–5.2 mgC m−3 (about 2.1 mgC m−3 on average) and 0.2–6.0 mgC m−3 (about 2.7 mgC m−3 on average) respectively in the two cruises. BB in the surface layer decreased from the Changjiang River estuary to high sea and from low latitude to high latitude. The results showed that bacterial growth was regulated by temperature, primary production and inorganic nutrient concentrations depending on different hydrographic conditions. In the surface and middle layers where the primary production can supply enough organic substrate, temperature was the main factor to control bacteria biomass. BB showed a good correlation between the surface and middle layers in both cruises. The distribution of nutrients during both cruises showed a similar decreasing trend from nearshore region and high latitude to offshore region and low latitude. High BB values were mainly recorded from samples in the middle layer where chl-a concentrations were also high, indicating primary production being strongly correlated with temperature over the ECS shelf. In the offshore area, phosphate and silicate became limiting factors for phytoplankton growth with indirect influence on BB. Bacteria played an important role in nitrogen regeneration process turning organic nitrogen to inorganic forms such as NH4 +. The increasing ratio of NH4 +/DIN could be a proof of that.  相似文献   

8.
Both nitrate (NO3−) and soluble reactive phosphate (PO43−) concentration in the freshwater end-member at the mouth of the Changjiang River have increased dramatically since the 1960s. Within the same period in the sea area, with surface salinity>30, NO3− concentration has shown an obvious increase, PO43− has not changed greatly and dissolved reactive silica (SiO32−) has deceased dramatically. An examination of the elemental ratio of NO3− to PO43− at the mouth of the Changjiang River did not show a systematic trend from the 1960s to 2000s largely because both nutrients increased simultaneously. In comparison, the elemental ratio of dissolved inorganic nitrogen (DIN) to PO43− in surface seawater, with salinity>22, has shown a clearly increasing trend. Furthermore, an overall historical change of the SiO32−:PO43− ratio has undergone a reverse trend in this area. Based on the changes of SiO32−:PO43− and DIN:PO43− ratios, we can conclude that an overall historical change of SiO32−:DIN ratio has decreased in this area from the 1950–1960s to 2000s. The argument that phytoplankton productivity in the Changjiang estuary has been enhanced by increasing nutrient input from the riverine transport was supported by these results. A comparative study analyzing the shift of phytoplankton composition from the mid-1980s to 2000s was also made. The results indicated that the average yearly percentage of diatom species in the Changjiang estuary has decreased from 84.6% during 1985–1986 to 69.8% during 2004–2005. Furthermore, the average yearly percentage of diatom abundance in the Changjiang estuary decreased from 99.5% during to 75.5% over the same time period, while the abundance of dinoflagellates has increased dramatically, from 0.7% to 25.4%.  相似文献   

9.
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   

10.
mODUCTIONTheislandsOfHaitan,Yuo,Dalian,DowiangandCaoguinPingtanCoUntyofFu-jianProvincearetogetherthewhtoasPingtan(25'l5'-25o45'E,l19"32'-12o"lo'N,EaStChinaSea).AmngthemHaitangIslanisthedrinoneinPingtanCotmty,andthelargestinFuianProvince.RngtanhaSanatuIalfishinggroUn(SeduMOUntaln)beingrenownedboghoutthecOUnnyandawelldeVfoPedaqUacultUreindusny.Pingtanwa-tersresotirceswerestirveyedforthefirsttimebytheauthorssothattheknowedgegainedcanbeaPPliedforbettereaploitahon,PIDechon,andde…  相似文献   

11.
Effects of salinity, pH, nitrogenous and phosphate nutrients on the growth rate of four species of benthic diatoms were studied by using the method of in situ optical density measurement. The optimal culture conditions for the four species of diatoms are as follows: forAmphora coffeaeformis, s 35; pH 8.5; NO3 −−N 1.54, NH4 +−N, 7.0; CO (NH2)2−N, 2.5 (mg/L); PO4 3−−P 1.13 (mg/L); forCocconeis scutellum varparva, s 30; pH 8.5; NO 3 − −N 3.08, NH 4 + −N 3.5, CO(NH2)2−N 5.0 (mg/L); pO 4 3− −P 0.283 (mg/L); forNavicula corymbosa s 25; pH 8.0; NO 3 − −N 1.54, NH 4 + −N 3.5 CO(NH2)2−N 5.0 (mg/L); PO 4 3− −P 0.565 (mg/L); forNavicula mollis. s 25; pH 8.0; NO 3 − −N 1.54, NH 4 + −N 1.75, CO(NH2)2−N 1.25 (mg/L); PO 4 3− −P 0.141 (mg/L). Part of the results of this paper were exchanged in the Fourth Asian Aquaculture Forum. Oct. 16–20. 1995. Beijing, P. R. China.  相似文献   

12.
The rates of photosynthesis and respiration ofPorphyra, Laminaria andUndaria were determined with an oxygenmeter at different temperatures in an enclosed continuous-flow system. The temperature coefficients of respiration and the net primary productivities for the three species were calculated. The spectacular rates of primary production were found to be as high as 270 g C m−2 forP. yezoensis, 2200 g C m−2 forL. japonica and 160 g C m−2 forU. pinnatifida annually. The low respiratory rates of these three species as well as low light compensation points especially at low temperatures are considered as a reason to save heat energy, resulting in a high productivity, especially in case ofLaminaria. Contribution No. 945 from the Institute of Oceanology, Academia Sinica. The paper was presented at the International Phycological Society Meeting, 19–22 Aug. 1980, Glasgow, UK.  相似文献   

13.
Branchiura sowerbyi in the Donghu Lake (Wuhan, China) completes its life cycle in one year. Its production rates were 6.7 g m−2 yr−1 (wet weight) during the period from April 1962 to May 1963 and 8.6g m−2 yr−1 during the period from August 1963 to August 1964. The standing stocks in corresponding periods were 1.9g m−2 (wet weight) and 1.1g m−2, and theP/B ratios were 3.6 and 7.8. Based on the standing stock during 1973–1975, an evaluation of recent productin levels ofB. sowerbyi in Donghu Lake has also been made (i.e. 5.7–33.5g m−2 yr−1).  相似文献   

14.
To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean, 234Th-238U disequilibrium was applied during the second Chinese National Arctic Research Expedition (July 15–September 26, 2003). The POC export fluxes are estimated from the measured profiles of the 234Th/238U activity ratios and the POC/PTh ratios. The average residence times of the particulate and dissolved 234Th in the euphotic zone are 33 d and 121 d, and their average export fluxes are 480 dpm/m2d and 760 dpm/m2d, respectively. The scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi Sea. The average residence time of 234Th increases from shelf to basin, while the export fluxes of 234Th decrease. The estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m2d, indicating that the western Arctic Ocean is an important carbon sink in summer due to efficient biological pump.  相似文献   

15.
Based on field data for nutrients collected on the continental shelf of the East China Sea (ECS) during summer 2006, the structure and variations of nutrients in every water mass related to the Taiwan Warm Current (TWC) were analyzed. The supplementary effect of nutrient of upwelling on harmful algal blooms (HABs) in the ECS was also estimated, based on upwelling data. Then the maintenance contribution of nutrient of upwelling to HABs was assessed. The results showed that N/P ratio is fairly low in both surface and deep layers of the TWC, which possibly controls nutrient structure of the HABs-frequently-occuring areas. In upwelling areas, the rate of phosphate (PO4-P) uptake exceeds that of nitrate (NO3-N) of the TWC. The TWC may relieve PO4-P limitation during the process of HABs. Furthermore, upwelling plays an important role in providing nutrients to HABs. After estimating nutrient fluxes (NO3-N, PO4-P, SiO3-Si) in the upwelling areas along a typical section (S07), the results showed that the nutrient uptake rate is the greatest at 10–20 m below euphotic zone, sustaining the ongoing presence of HABs. The uptake rate of PO4-P is the highest among dissolved inorganic nutrients. Therefore, upwelling is most likely the main source of PO4-P supply to HABs.  相似文献   

16.
The standing stock and primary production of benthic microalgae on tidal flats were measured seasonally at 3 transects (Puqing, Dahengchuang and Puqi) in Yueqing Bay during 2002 2003. The results showed that the integral chlorophyll a (Chl a) concentration in tidal flat mud exhibited a seasonal variation with the order of magnitude: winter (14.0 4.2 mg m-2) > spring (13.0 6.3 mg m-2) > autumn (7.7 5.9 mg m-2) > summer (4.6 3.2 mg m-2). The primary production showed an order of magnitude: spring (270.5 224.9 mgC m-2 d-1)>winter (238.7 225.5 mgC m-2 d-1)>autumn (214.1 56.2 mgC m-2 d-1)>summer (71.6 44.6 mgC m-2 d-1). Both chlorophyll a and primary production showed maximum values in the surface layer of sediment, and decreased rapidly with increasing depth due to sun light limitation. The results of variance analysis indicated that seasonal variation and tidal flat condition affected Chl a greatly, but had no significant effect on primary production. The annual primary production of benthic microalgae on tidal flats in Yueqing Bay was estimated at 16143 tons carbon, which is sufficient to support 1.02×105 tons shellfish production. The environmental factors affecting chlorophyll and primary production on the tidal flats in Yueqing Bay were discussed. By comparing with other bays on China’s coast, it was observed that Yueqing Bay is a region with high benthic microalgae standing crop and primary production, which may be related to the type of its sediment.  相似文献   

17.
Sinoe vertical transport of nutrients and dissolved oxygen are quite important in the water col-umn and have drawn serious attention these recent years, a one-dmension numerical model is tried to simulate the vertical distribution of nutrients and dissolved oxygen in June at two research sites in the southemTaiwan Strait. Physical transport parameters are calibrated by temperature simulation, and thenare used to simulate the profiles of NO_3, PO_4 and dissolved oxygen. The simulation was generally success-ful for both stations. The importance of various factors, such as upwelling tidal current andbiogeochemical activities, which influence the vertical distribution of nutrients and dissolved oxygen, is revealed by analysis of the modeling results. Some important rates, fluxes and ratios are also estimated anddiscussed on the basis of simulation.  相似文献   

18.
Investigations from August, 1985 to July , 1986 showed that the high concentration area of PO4-P , SiO3-Si and NO3-N gradually reduced with the reduction of the area of the Changjiang River diluted water from summer, autumn to winter , and that the seasonal distributions and variations of the nutrients concentrations were mainly controlled by the river flow and were also related to the growth and decline of phytoplankton . The conservation of SiO3-Si and NO3-N in the estuary in the flood season was poorer than that in the dry season .. The behaviour of PO4-P in the estuary shows that aside from -biological removal, buffering of PCU-P is possible in the estuary . The highest monthly average concentrations and annual average concentrations in the river mouth were respectively 0.88 and 0.57 umol/L for PO4-P,191.5 and 96.2 umol/L for SiO3-Si, and 81.6 and 58.6 umol/L for NOs-N . The Changjiang's annual transports of PO4-P , SiO3-Si and NO3-N to the sea were about 1.4×104tons , 204.4×104 tons and 63.6×104  相似文献   

19.
The SCENTO-System was used to study the carbon dynamics between phytoplankton primary production and heterotrophic bacterial secondary production. Most of the methods used nowadays in situ for limnological synecology studies were applied. Primary production measurement showed an increasing tendency with increasing content of chlorophylla. It provided a true photosynthetic rate lying within the range of eutrophic lakes. Net EOC released from the algae ranged from 8.5 to 27.5 μg C l−1(6h)−1. Accompanying the algal products the number of bacteria increased from 1.475 ×109 to 8.074×109 cells l−1. The bacterial mean cell volume was small, between 0.0315 and 0.0548μm3. Bacterial carbon production from direct growth estimates was compared with independent calculations of bacterial growth from EOC uptake and3H-thymidine incorporation. Direct estimates were 2.97–10.0 μg Cl−1 (24h)−1 with the exception of a zero-growth on the third day. EOC uptake was 123.5–191.0 μg Cl−1 (6h)−1. That calculated from3H-thymidine incorporation was 0.2–0.5 μg Cl−1 (6h)−1.14C-glucose dark uptake ran parallel to the increasing bacterial biomass. The respiration of glucose was 6.5% (avg.) of the gross uptake. Since the system operated without grazing pressure, a real carbon flow from primary production to bacterial secondary production could be observed.  相似文献   

20.
Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a (Chl-a) levels. The Chl-a growth rates (k) ranged from 0.60–1.67 d−1, while microzooplankton grazed the Chl-a at rates (g) of 0.29–0.62 dt-1. The addition of C. sinicus enhanced the Chl-a growth rate (Z) by 0.004–0.037 d−1 ind.−1 L. C. sinicus abundance ranged from 84.1–160.9 ind. m−3, which occupied 90.7%–99.1% of the copepod (>500 μm) population. The in-situ increase in phytoplankton by C. sinicus community was estimated to be 0.000 4–0.005 9 d−1. These results showed that microzooplankton were the main grazers of phytoplankton, while C. sinicus induced a slight increase in the levels of phytoplankton.  相似文献   

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