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1.
The role of zooplankton in the vertical mass flux in the Kara and Laptev seas was studied during cruise 63 of the R/V Akademik Mstislav Keldysh in August–October 2015. Mass fluxes were estimated using sediment trap samples. The maximum values of the total vertical flux (19600 mg m?2 day?1) and particulate organic carbon (POC) flux (464 mg C m?2 day?1) were measured close to the Lena River Delta in the Laptev Sea. In the Kara Sea, the total flux (80–2700 mg m?2 day?1) and the POC flux (17–130 mg C m?2 day?1) were substantially higher than the estimates published earlier. The fecal pellet flux varied from 2 to 92 mg C m?2 day?1 and made up 4–190% of the total organic carbon flux. The mineral composition of fecal pellets largely mirrored that of suspended particulate matter. Clay minerals in the fecal pellets were more abundant than in particulate matter in the areas with noticeable freshwater impact. The flux of zooplankton carcasses varied from 0.1 to 66.4 mg C m?2 day?1 and made up 0.2–72% of total POC flux. The results are discussed in relation to the abundance and composition of zooplankton, the concentration and composition of suspended particulate matter, hydrophysical conditions, and methods of sample preparation for analysis.  相似文献   

2.
In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l?1 and from 0.28 to 5.24 mg l?1 and particulate phosphorus (PP) varied from 0.71 to 5.18 μg l?1 and from 0.78 to 20.34 μg l?1, respectively. The mean values of chlorophyll and primary productivity were 1.94 mg m?3 and 938.1 mg C m?2 day?1 in the coastal waters and 4.3 mg m?3 and 636.5 mg C m?1 day?1 in the estuarine waters, respectively.POCchl ratios were low in June and October even when POC values were quite high. The POC in surface waters was linearly correlated with the chlorophyll content. Also PP increased when chlorophyll and primary productivity remained high. The results suggest that the phytoplankton was sharply increasing and contributed to POC and PP content. The percentage of detritus calculated from the intercept values of chlorophyll on POC varied from 46 to 76% depending on season. Results indicate that the major portion of POC and PP during postmonsoon (October–January) is derived from phytoplankton production while the allochthonous matter predominate during monsoon (June–September).  相似文献   

3.
The studies were performed from September 10 to 29 of 2007 in the Kara Sea in transects westward of the Yamal Peninsula, near the St. Anna Trough, in the Ob River’s estuary, and on the adjacent shelf. The concentration of chlorophyll a in the euphotic layer changed from 0.02 to 4.37 mg/m3, amounting on the average to 0.76 mg/m3. The primary production in the water column varied from 10.9 to 148.0 mg C/m2 per day (the mean was 56.9 mg C/m2 per day). It was shown that frontal zones divided the Kara Sea into distinct areas with different productivities. The maximum levels of the primary production were measured in the deep part of the Yamal transect (132.4 mg C/m2 per day) and the shallow Kara Sea shelf near the Ob River’s estuary (74.9 mg C/m2 per day). The characteristics of these regions were the low salinity of the surface water layer (19–25 psu) and the elevated silicon content (12.8–28.1 μg-atom Si/l), which is explainable by the river water inflow. The frontal zones of the Yamal Current in the Yamal and Ob transects displayed high values of the assimilation numbers, amounting to 2.32 and 1.49 mg C/mg of chlorophyll per h, respectively (the maximal for the studied regions).  相似文献   

4.
Sediment trap arrays were deployed at two deep ocean stations, one in the Bering Sea and the other in the Gulf of Alaska, in the summer of 1975. The sediment trap was constructed of a pair of polyethylene cylinders (0.185 m2 opening) with funnel-shaped bases. The trap is equipped with a lid which is closed before recovery by a tripping messenger system triggered by an electric time release. 37–68% of the total organic carbon fluxes (37–38% in the Bering Sea; 48–68% in the Gulf of Alaska) were represented by large particles (67µm<) such as fecal matter and fecal pellets which contributed minor fractions to the total particulate organic matter concentration in sea water. The total fluxes were 11.1 and 14.2 mg C m–2d–1 at 1,510 and 2,610 m respectively at the station (3,800 m) in the Bering Sea, and were 7.60, 4.66 and 3.27 mg C m–2d–1 at 900, 1,500 and 1,875 m respectively at the station (4,150 m) in the Gulf of Alaska. The former values are several times greater than the latter, suggesting that there is a regional variation in the vertical carbon flux in deep layers. The fluxes were approximately equivalent to 1 to 3% of primary productivity in the overlying surface layers. These observations suggest that deep-water ecosystems may be influenced by relatively rapid sinking of large particles such as fecal matter and fecal pellets from near surface production.  相似文献   

5.
We investigated a year-long (September 1992 to August 1993) time series of total mass, calcium carbonate, organic carbon, opal, and alkenone fluxes in sinking particles collected with sediment traps moored at 1770 and 4220 m in the central equatorial Pacific. The total mass fluxes varied from 14.7 to 68.7 mg/m2/day at 1770 m, with greater fluxes in October–November and February–April, and from 14.6 to 50.4 mg/m2/day with peak fluxes during October–November at 4220 m. High flux in the spring season shown at 1770 m was not indicated at 4220 m; instead, a slight increase was shown during a broad period from March to June. The calcium carbonate fluxes varied from 10.8 to 49.1 mg/m2/day with higher fluxes in October–November and March–April at 1770 m, and from 8.9 to 37.0 mg/m2/day with a higher flux in October–November at 4220 m. The organic carbon fluxes varied from 0.36 to 5.91 mg/m2/day, with higher fluxes in October–November and March–April at 1770 m, and from 0.72 to 2.58 mg/m2/day at 4220 m. The annual mean organic carbon flux was 1.84 and 1.28 mg/m2/day at 1770 and at 4220 m, respectively. These values were less than half of those reported for the EqPac sediment trap experiment. The opal fluxes varied from 0.55 to 4.4 mg/m2/day at 1770 m and from 1.23 to 2.95 mg/m2/day at 4220 m. Alkenone fluxes varied significantly from 0.05 to 0.84 μg/m2/day, with high values in November, February–March, and June at 1770 m. For the 4220 m trap, these values ranged from 0.05 to 0.25 μg/m2/day, with slightly higher fluxes in April–May and June–July, which followed periods of high alkenone fluxes observed in February–April and June–July, respectively, at 1770 m depth. These values were remarkably low compared with those reported by the previous studies at other sites. U37K′ values were constantly high >0.95 throughout the collection period. However, relatively low U37K′ values (0.92 and 0.93) were occasionally observed during February to March. Estimated alkenone temperatures from those U37K′ values were about 27–29°C and consistent with the observed temperature of the upper layer at ca.100 m depth. The seasonal change of the U37K′ values could be affected by not only water temperature but also the relative amount of ‘warm’ and ‘cold’ types of alkenone producer in the central equatorial Pacific.  相似文献   

6.
南沙海域上层海水碳垂直通量的初步研究   总被引：6，自引：0，他引：6  
根据１９９０年５－６月在南沙海域４个站点投放颗粒物捕集器采集样品的分析结果，计算了该海域上层海水碳垂直通量。结果表明：（１）南沙海域上层海水颗粒有机碳总生成量为２９８ｍｇ／（ｍ＾２．ｄ），其中３５％分解参与再循环，６５％以颗粒形式离开真光层向下输送；（２）颗粒有机碳向下通量为１９３ｍｇ／（ｍ＾２．ｄ）。总溶解无机碳穿过跃层向上垂直通量为３６００ｍｇ／（ｍ＾２．ｄ），真光层颗粒无机碳向下通量为２７ｍ  相似文献   

7.
New maps of the mean monthly distribution of chlorophyll and the primary production in the Kara Sea were compiled using joint processing of CZCS (1978–1986), SeaWiFS (1998–2005), and MODIS (2002–2006) satellite data and field measurements. The annual primary production of phytoplankton is estimated at 22.3 × 106 t of C per year or 70 mg of C/m2 per day. The results of the calculations of the organic carbon budget in the Kara Sea are presented.  相似文献   

8.
The results of microbiological, biogeochemical, and isotope geochemical studies in the Kara Sea are described. The samples for these studies were obtained during the 54th voyage of the research vessel Akademik Mstislav Keldysh in September 2007. The studied area covered the northern, central, and southwestern parts of the Kara Sea and the Gulf of Ob. The quantitative characteristics of the total bacterial population and the activity of the microbial processes in the water column and bottom sediments were obtained. The total population of the bacterioplankton (BP) varied from 250000 cells/ml in the northern water area to 3000000 cells/ml in the Gulf of Ob. The BP population depended on the content of the water suspension. The net BP production was minimal in the central water area, amounting to 0.15–0.2 μg C/(l day), and maximal (0.5–0.75 μg C/(l day)) in the Gulf of Ob. The organic material at the majority of the stations in the Ob transect predominantly contained light carbon isotopes (−28.0 to −30.18‰) of terrigenous origin. The methane content in the surface water layer varied from 0.18 to 2.0 μl CH4/l, and the methane oxidation rate changed in the range of 0.1–100 nl CH4/(l day). The methane concentration in the upper sediment layer varied from 30 to 300 μl CH4/dm3; the rate of the methanogenesis was 44 to 500 nl CH4/(dm3 day) and that of the methane oxidation, 30 to 2000 nl CH4/(dm3 day). The rate of the sulfate reduction varied from 4 to 184 μg S/(dm3 day).  相似文献   

9.
Research was implemented from September 15 through October 4, 2011 in the Kara Sea along transects located southeastwards Novaya Zemlya, in the St. Anna Trough, the Yenisei River estuary, and the adjacent shelf. The concentration of chlorophyll a was the highest in the photic zone (0.05–2.30 mg/m3, on average, 0.80 ± 0.37 mg/m3). The maximal concentration of Chl a at most of the stations located in the water layer of 7–30 m. Integral primary production in the water column varied from 3.0 to 151.0 mg C/m2 per day, on average, 37.2 ± 36.6 mg C/m2 per day. The maximal rate of primary production at most of the stations has been observed for the surface layer of the water column. Within the upper mixed water layer, relative primary production was from 31 to 100% (on average, 77 ± 20%). The most productive zone was the waters along Yenisei transect. In the estuary and at the adjacent shelf, primary production was 50 mg C/m2 per day, exceeding the range observed for other areas by 1.5–2.0 times. The concentrations of silica and nitrogen together with light regime and water temperature were the major limiting factors affecting the primary production rate in the Kara Sea in autumn.  相似文献   

10.
Benthic macroinvertebrates and small stones were collected from a riffle in the Ashley River, North Canterbury, New Zealand, on 12 occasions within a 132‐day period following a particularly large flood in 1986. Despite the occurrence of smaller floods during this period, benthic macroinvertebrate communities and stone surface organic layers recovered rapidly. Mean concentration of stone surface organic carbon increased from 0.23 g/m2 to 1.01 g/m2 stone surface in the first 23 days after the flood and chlorophyll a concentration increased from 0.13 mg/m2 (day 3) to 9.2 mg/m2 by day 132. Minor floods during the recovery period had little effect on organic layer biomass. Mean faunal density increased from 230/m2 to 7920/m2 during this time and taxon richness from 7 to 21 per 5 benthic samples. Immediately after the flood and throughout the study period the fauna was dominated by larvae of Deleatidium (Ephemeroptera: Leptophlebiidae), Hydora (Coleoptera: Elmidae), and Chironomidae. Re‐establishment of Deleatidium populations in previously denuded brands was effected by oviposition, egg‐hatching, and larval immigration. Minor braids are likely to represent important epicentres from which recolonisation proceeds.  相似文献   

11.
Seasonal variation of the integrated primary production (IPP) and surface chlorophyll (Chl0) in different regions of the Kara Sea was studied from satellite data obtained by the MODIS-Aqua colour scanner and averaged for 2003–2015. The minimum variation of Chl0 concentration during the growing season (from April to October) was 1.5 times in southwestern region and 2 times in the northern region of the sea. It was found that the Chl0 concentration increased slightly in all regions by the end of the growing season. The maximum IPP value recorded in June coincided with the peak level of photosynthetically active radiation (PAR) and maximum river discharge. The IPP value varied in a wider range compared with the Chl0 concentration. The ratio of the maximum and minimum monthly average IPP values varied from 8.9 times in Southwestern region to 11.7 times in the Northern region of the sea. The average increase in the Chl0 concentration was 1.7 times (from 0.78 mg/m3 in April to 1.29 mg/m3 in October). The IPP value varied by a factor of 10.7 (from 26 mg C/m2 per day in October to 279 mg C/m2 per day in June). The article also discusses the influence of water column stratification, the concentration of nutrients, the PAR level, and river discharge on the seasonal IPP dynamics in the Kara Sea.  相似文献   

12.
A time-series sediment trap was deployed from December 1994 to February 2002 at the mouth of Tokyo Bay (35°03′ N, 139°40′ E; water depth, 850 m). Sinking particles were obtained with a time interval of one week at a depth of approximately 100 m above the sea floor. Observed total mass fluxes varied from 3.3 to 226.7 g/m2/day with an average of 28.0 g/m2/day. Concentrations of rare earth elements, Al, Ca and Si in particulate materials were measured. The combustible fraction at 450°C is assumed to be equivalent to the organic matter content. Contents of biogenic materials, namely organic matter, opal and calcium carbonate, were about 30% and the content of lithogenic material was about 70%. Using La/Yb ratios of particles from the sediment trap and Tama-gawa River and surface sediment of Tokyo Bay, it was estimated that about 50% of the lithogenic particles collected in the sediment trap at the mouth of Tokyo Bay originated from resuspended surface sediment in Tokyo Bay. An increasing trend of Opal/CaCO3 ratio in the sinking particles was found in the spring season. It is suggested that the relative increase of diatoms is due to the decreasing dissolved inorganic nitrogen input into Tokyo Bay.  相似文献   

13.
In 1998–1999, beam attenuation coefficient (bac) profiles, suspended particulate matter (SPM) and particulate organic carbon (POC) concentrations were assessed during five cruises in the Saronikos Gulf, eastern Mediterranean, Greece. SPM and POC concentrations (0.05–1.84 mg l−1 and 10.2–468.6 μg l−1, respectively) exhibited strong spatial and temporal variations, related to the different environmental characteristics of various sectors of the gulf, including wind regime and biological productivity. The Elefsis and Keratsini bays, as well as the area around Psyttaleia Island, showed the highest POC concentrations. The vertical distribution of POC at stations in the western basin, as well as in the inner and outer Saronikos Gulf is characterised by higher POC concentrations in surface waters, associated with higher biological activity. The wastewater treatment plant effluents discharged south of the Psyttaleia Island are a major source of organic particles which directly influence the intermediate water layers, at least during the stratification period. Assessments of relationships between bac and SPM or POC concentrations revealed a relatively strong correlation between bac and POC. An equation converting bac readings to POC concentration was established which can be applied to historical and/or future bac measurements, independently of season. POC concentrations estimated from calibrated continuous transmissometer readings were used to estimate the standing stock of POC in the Saronikos Gulf, which varied between 6,110×106 and 13,450×106 g C during the period June 1998 to February 1999.  相似文献   

14.
Particulate matter from the atmosphere over the Atlantic Ocean along the South American and African Continents has been analyzed for organic tracers from natural and biomass burning emissions. The major biomarker compounds characterized are natural products from continental vegetation consisting primarily of epicuticular wax components. For example, n-alkanes ranged from C25 to C35, with an odd carbon number predominance and carbon maxima (Cmax) at 29 or 31. Concentrations of n-alkanes varied from 0.3 to 680 ng/m3. Nevertheless, n-alkanols are the dominant terrestrial tracers in almost all samples (concentrations from 0.1 to 780 ng/m3) and ranged from C22 to C34 with an even carbon number predominance. Despite the major presence of the natural tracers, organic components from biomass burning emissions are also present in the particulate matter. The major tracers from this source are thermal degradation products from the biopolymer cellulose, namely the dianhydromonosaccharide derivatives levoglucosan, galactosan, and mannosan. In general, the concentrations of levoglucosan, the major derivative from this source in all samples, varied from 0.0008 to 0.15 ng/m3 in atmospheric samples collected over the ocean and from 0.04 to 4860 ng/m3 in terrestrial particulate matter, used as reference in this study. Dehydroabietic acid, another marker compound emitted from burning of Gymnosperm fuel, is also detectable in most oceanic samples at concentrations ranging from 0.0001 to 0.4 ng/m3, whereas in terrestrial aerosol particulate matter, this component is present at much higher concentrations (0.23–440 ng/m3). The presence of these tracers in atmospheric particulate matter over the ocean confirms the long-range transport of smoke from biomass burning off the continents.  相似文献   

15.
The primary productivity in coastal water adjacent to the Kuroshio off Shimoda was measured as part of the International Biological Program. The total amount of chlorophylla in the euphotic zone varied widely from 20 mg/m2 to 60 mg/m2 throughout the year and the maximum values were measured in early summer. These values were higher than those in the Kuroshio but agreed with those in the Oyashio. Vertical differentiation of photosynthetic characteristics was well developed and it was strongly related to the stratification of the water column. The light-saturated photosynthetic rate of surface phytoplankton varied from 5.8 mg C/(mg chl.h) in May to 2.0 mg C/(mg chl.h) in January. These rates were higher than those in the Kuroshio. The daily primary production was estimated by the chlorophyll method. Highest value was 0.5–1.5 g C/(m2day) in early summer and the lowest was 0.2 g C/(m2day) in winter. The primary productivity in the coastal water studied accorded fairly well with that in the Oyashio.Contribution No. 239 from Shimoda Marine Biological Station. This study is part of JIBP project entitled Studies on the Dynamic Status of the Biosphere, a Special Research Project supported by the Ministry of Education.  相似文献   

16.
Production parameters of surface phytoplankton were measured along three transects: La Manche-Cape Town (I); Cape Town-54°S (II); 0°-49°W (along 54°S) (III). The Canary upwelling waters were most productive along transect I, where the surface chlorophyll a (Chl 0) and the surface primary production (PP 0) were as high as 4.3 mg/m3 and 173 mg C/m3 per day, respectively. Mosaic patterns in the distribution of these parameters were recorded in the northeastern regions of the South Subtropical Anticyclonic Gyre (Chl 0 = 0.03–0.35 mg/m3; PP 0 = 1.6–12.6 mg C/m3 per day). Along transect II, the average twofold southward increase in Chl 0 (from 0.2 to 0.4 mg/m3) and the concurrent decline of the phytoplankton assimilation activity ( AN 0) resulted in deviations from typical latitudinal changes inPP 0. At most sites, PP 0 values varied between 6 and 15 mg C/m3 per day. Negligible changes in Chl 0 (0.36–0.85 mg/m3), PP 0 (8–19 mg C/m3 per day), and AN 0 (0.7–1.6 mg C/mg chl a per hour) were registered for the oceanic waters along transect III. Along all the transects, PP 0 depended on Chl 0 to a greater extent than AN 0. The values of the latter parameter were largely determined by the water temperature and showed a slight correlation with the insolation. Along transect II, the integrated primary production (PP int) and the layer-integrated chlorophyll a in the upper 200 m (Chl 0–200) generally varied from 180 to 360 mg C/m2 per day and from 30 to 70 mg/m2, respectively. In the Polar Front region, an increase in Chl 0–200, PP int, Chl 0, and PP 0 up to respective values of 190 mg/m2, 520 mg C/m2 per day, 1.2 mg/m3, and 32 mg C/m3 per day was observed. A comparison of the water column (0–100 m) stability with the vertical distribution of the primary production and chlorophyll content along transect II implies that the thick (>100 m) upper mixed layer (UML) formed in response to the strong water cooling and wind forcing was largely responsible for the limited primary production in the Subantarctic and Antarctic regions. The large UML thickness resulted in an intense removal of plant cells from the photosynthetic layer and light starvation of a significant (up to 60%) part of the phytoplankton community.  相似文献   

17.
Sedimentation of particulate carbon from the upper 200–300 m in the central Greenland Sea from August 1993 to June 1995 was less than 2 g C m−2 yr−1. Daily rates of sedimentation of particulate organic carbon reached highest values of about 18 mg m−2 d−1 in fall 1994. For total particulate material, maximum rates of sedimentation of about 250 mg m−2 d−1 were recorded in spring and fall 1994. For chlorophyll equivalent, highest rates of sedimentation of about 140 μg m−2 d−1 were recorded in spring 1994. As reported in related investigations, the transient accumulation of DOC in surface waters during summer, as well as respiration and mortality of deep overwintering zooplankton stocks, appeared to dominate the fate of photosynthetically fixed organic carbon. The above processes may account for roughly 43 g C m−2 in the upper 200 m of the central Greenland Sea. For comparison, the seasonal deficit in dissolved inorganic carbon was reported to be about 23 g C m−2 in the upper 20 m of surface water, and estimates for new annual production were reported to be about 57 g C m−2. In our investigation, the biological carbon pump was not unusually effective in transporting carbon out of the productive surface layer.  相似文献   

18.
Based on balance calculations with the use of a spatially detailed mathematical model for transport and sedimentation of the particulate matter adjusted to the conditions of the Sea of Azov, particular spatiotemporal features of the terrigenous sedimentation in the second half of the 20th century are recognized. The general tendency for the deceleration of the accumulation of terrigenous sediments and for the decrease in the areas with a negative balance of the terrigenous matter is related to the 2.5-fold fall in the volumes of the matter supplied from land. During the period considered, the intensity of the sedimentation decreased from 1000 to 400 g/m2/year. The accumulation of terrigenous sediments proceeds in the regions where the sources of the matter supply are concentrated and where features of the bottom morphology and hydrodynamical activity are favorable for the sedimentation: in Taganrog and Temryuk bays. In the central part of the sea, the intensity of the sedimentation comprises a value of about 300 g/m2/year. In Taganrog Bay and in the sea proper, areas with a negative balance of terrigenous sedimentary matter increased up to 30%.  相似文献   

19.
An enhancement of aeolian inputs to the ocean due to a future increase in aridity in certain parts of the world is predicted from global change. We conducted an experimental simulation to assess the biological response of NW Mediterranean coastal surface waters to an episodic dust addition. On the assumption that planktonic growth was limited by phosphorus, dust effects were compared to those induced by equivalent enrichments of phosphate. The experiment analyzed the dynamics of several parameters during one week: inorganic nutrients, total and fractioned chlorophyll a, bacterial abundance, phytoplankton species composition, abundance of autotrophic and heterotrophic flagellates, particulate organic carbon and particulate organic nitrogen. The maximum addition of dust (0.5 g dust L−1) initiated an increase in bacterial abundance. After 48 h, bacterial numbers decreased due to a peak in heterotrophic flagellates and a significant growth of autotrophic organisms, mainly nanoflagellates but also diatoms, was observed. Conversely, lower inputs of dust (0.05 g dust L−1) and phosphate enrichments (0.5 μmol PO43− L−1) only produced increases in phototrophic nanoflagellates. In our experiment, dust triggered bacterial growth, changed phytoplankton dynamics and affected the ratio of autotrophic to heterotrophic biomass, adding to the variability in the sources that affect system dynamics, energy and carbon budgets and ultimately higher trophic levels of the coastal marine food web.  相似文献   

20.
In October and November 2002, high and relatively high values of the chlorophyll a concentration at the sea surface (C chl) were observed in the English Channel (0.47 mg/m3), in the waters of the North Atlantic Current (0.25 mg/m3), in the tropical and subtropical anticyclonic gyres (0.07–0.42 mg/m3), and also in the southwestern region of the southern subtropical anticyclonic gyre (usually 0.11–0.23 mg/m3). The central regions of the southern subtropical anticyclonic gyre (SATG) and the North Atlantic tropical gyre (NATR) were characterized by lower values of C chl (0.02–0.08 mg/m3 for the SATG and 0.07–0.14 mg/m3 for the NATR). At most of the SATG stations, the values of the surface primary production (C phs) varied from 2.5 to 5.5 mg C/m3 per day and were mainly defined by the fluctuations of C chl (r = +0.78) rather than by those of the assimilation number (r = +0.54). The low assimilation activity of phytoplankton in these waters (1.3–4.6 mg chl a per hour) pointed to a lack of nutrients. An analysis of the variability of their concentration and the composition of photosynthetic pigments showed that, in the waters north of 30° N, the growth of phytoplankton was mostly restricted by the deficiency of nitrogen, while, in more southern areas, at the majority of stations (about 60%), the phosphorus concentrations were the minimum. At the low concentrations of nitrates and nitrites, ammonium represented itself as a buffer that prevented planktonic algae from extreme degrees of nitric starvation. In the tropical waters and in the waters of the SATG, the primary production throughout the water column varied from 240 to 380 mg C/m2 30° per day. This level of productivity at stations with low values of C chl (<0.08 mg/m3) was provided by a well-developed deep chlorophyll maximum and a high transparency of the water. The light curves of photosynthesis based on in situ measurements point to the high efficiency of utilizing the penetrating solar radiation by phytoplankton on cloudy days.  相似文献   

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