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1.
The concentrations of the trace metals Cd, Cu, Fe, Ni, Pb and Zn in the Göta River estuary have been investigated. The following metal fractions have been determined: acid-leachable, dissolved, labile and particulate.The estuary represents a salt wedge type estuary and is situated in a densely populated region of Sweden. The metal concentrations found for the dissolved fraction is in the range of what can be considered as background levels for freshwater. It is difficult to evaluate any estuarine processes other than conservative mixing for Cd, Cu, Ni and Zn. The dissolved levels in the freshwater end member are Cd, 9–25 ngl?1; Cu, 1·1–1·4 μgl?1; Fe, 20–75 μg l?1: Ni, 0·7–0·9 μg l?1: Pb 0·09–0·2 μg l?1; and Zn, 6–7 μg l?1:The results from the acid-leachable fraction show that at high suspended load the particles sediment in the river mouth. The trace metal levels in this fraction are subject to large variations.  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.
Appropriate conditions have been achieved for the accurate, rapid, and highly precise shipboard simultaneous determination of dissolved organic carbon and total dissolved nitrogen in seawater by high temperature catalytic oxidation. A nitrogen-specific Antek 705D chemiluminescence detector and a CO2-specific LiCor Li6252 IRGA have been coupled in-series with a Shimadzu TOC-5000 organic carbon analyser. Precision of both simultaneous measurements is ≤1.5%, i.e. ±1 μmol C l−1 and ±0.3 μmol N l−1, respectively. Quality of analysis is not compromised by vibrations associated with ocean going research vessels.  相似文献   

4.
The crab Carcinus maenas (L.) and the barnacle Elminius modestus Darwin were exposed to a range of dissolved concentrations of Zn, Cu and Cd for 21 days in artificial seawater. Accumulation of Zn and Cu by crabs has been interpreted in terms of the presence of a regulation mechanism to maintain constant body concentrations (83·2 ± 19·4 μg Zn g?1 dry wt.; 39·8 ± 9·8 μg Cu g?1 dry wt.) under varying external dissolved metal levels, until a threshold dissolved metal concentration (c. 400 μg Zn l?1; c. 170 μg Cu l?1) beyond which net accumulation of metal begins. Cadium appears to be accumulated by C. maenas at all exposures with no evidence for regulation of body cadmium concentrations. Exposure of E. modestus to Zn, Cu or Cd caused net accumulation of the respective metal in the bodies of the barnacles, with no evidence for regulation of body metal concentrations.  相似文献   

5.
The annual flux of biologically produced organic carbon from surface waters is equivalent to annual net community production (NCP) at a steady state and equals the export of particulate and dissolved organic carbon (POC and DOC, respectively) to the ocean interior. NCP was estimated from carbon budgets of salinity-normalized dissolved inorganic carbon (nDIC) inventories at two time-series stations in the western subarctic (K2) and subtropical (S1) North Pacific Ocean. By using quasi-monthly biogeochemical observations from 2004 to 2013, monthly mean nDIC inventories were integrated from the surface to the annual maximum mixed layer depth and corrected for changes due to net air–sea CO2 exchange, net CaCO3 production, vertical diffusion from the upper thermocline, and horizontal advection. The annual organic carbon flux at K2 (1.49 ± 0.42 mol m?2 year?1) was lower than S1 (2.81 ± 0.53 mol m?2 year?1) (p < 0.001 based on t test). These fluxes consist of three components: vertically exported POC fluxes (K2: 1.43 mol m?2 year?1; S1: 2.49 mol m?2 year?1), vertical diffusive DOC fluxes (K2: 0.03 mol m?2 year?1; S1: 0.25 mol m?2 year?1), and suspended POC fluxes (K2: 0.03 mol m?2 year?1; S1: 0.07 mol m?2 year?1). The estimated POC export flux at K2 was comparable to the sum of the POC flux observed with drifting sediment traps and active carbon flux exported by migrating zooplankton. The export fluxes at both stations were higher than those reported at other time-series sites (ALOHA, the Bermuda Atlantic Time-series Study, and Ocean Station Papa).  相似文献   

6.
The stable isotopes of dissolved organic carbon (DOC) are a powerful tool for distinguishing sources and inputs of organic matter in aquatic systems. While several methods exist to perform these analyses, no labs routinely utilize a high temperature combustion (HTC) instrument. Advantages of HTC instruments include rapid analysis, small sample volumes and minimal sample preparation, making them the favored devices for most routine oceanic DOC concentration measurements. We developed a stable carbon DOC method based around an HTC system. This method has the benefit of a simple setup, requiring neither vacuum nor high pressures. The main drawback of the method is a significant blank, requiring careful accounting of all blank sources for accurate isotopic and concentration values. We present here a series of experiments to determine the magnitude, source and isotopic composition of the HTC blank. Over time, the blank is very stable at  20 ng of carbon with a δ13C of − 18.1‰ vs. VPDB. The similarity of the isotopic composition of the blank and seawater samples makes corrections relatively minor. The precision of the method was determined by oxidizing organic standards with a wide isotopic and concentration range (− 9‰ to − 39‰; 18 μM to 124 μM). Analysis of seawater samples demonstrates the accuracy for low concentration, high salinity samples. The overall error on the measurement is approximately ± 0.8‰.  相似文献   

7.
Heterotrophic mineralization of dissolved organic nitrogen (DON) can be a major source of N for primary producers. During the summer growing season in mesooligotrophic Castle Lake, dissolved inorganic nitrogen (DIN) is often below detection (<0.1 μg-atom N l−1) whereas DON can vary between 7 and 17 μg-atom N. The heterotrophic metabolism of glutamate resulted in the recycling of both carbon and nitrogen, but not at the same rate. The uptake of 15N- and 14C-labeled glutamate showed that C was preferentially assimilated relative to N resulting in an N-mineralization rate of 2.5–3.0 ng-atom N l−1 h−1. This suggests that heterotrophs in Castle Lake are not N-deficient, and metabolism of organic compounds results in the release of DIN which is available for primary production.  相似文献   

8.
The paper reports on new data focusing on organic carbon contained in aeolian material and precipitation falling on coastal and water areas of the northeastern part of the Sea of Azov. Atmospheric deposition was sampled in 2006–2014. The particulate organic carbon content varied from 4 to 27% in aeolian dust samples. The concentration of the organic carbon dissolved in rainwater was from 1.6 to 4.3 mg C/L, and from 0.9 to 16.6 mg C/L in snow. The particulate organic carbon content varied from 2 to 43% in snow. Intensity of aeolian dust settling decreased from 178 to 33 mg/m2 per day with distance from a source of dust; in contrast, the relative content of organic matter increased. In a spring–summer season the aeolian organic carbon fluxes varied from 12 to 18 mg C/m2 per day in Rostov-on-Don, from 28 to 48 mg C/m2 per day on the Gulf of Taganrog coast, and from 20 to 80 mg C/m2 per day in the water area of the Gulf of Taganrog.  相似文献   

9.
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   

10.
Dissolved organic carbon (DOC) concentrations in surface waters of the Pacific Ocean during October–November, 1995, were determined using a high-temperature combustion method. The DOC in the surface mixed-layer was approximately homogeneous with a concentration between 55 and 89 μmol C l−1. This homogeneity indicates that there is a strong control of the vertical distribution of DOC by mixing processes. The DOC concentrations in the mixed-layer in the subtropical region were up to 27 μmol C l−1 higher than in the tropical region. This difference reflects the subtropical accumulation and the tropical export of DOC. There is a significant positive correlation between DOC and chlorophyll a concentrations in the mixed-layer of the North Pacific subtropical region, suggesting that phytoplankton is the primary source of DOC accumulated in this region. Calculations using simple box models suggest that DOC export in the tropical region (0–50 m depth, 10°N-10°S, along 160°W) occurs primarily by poleward advection at a rate of 0.5–3 mmol C m−2day−1. A comparison with estimates of the export rate of particulate organic carbon published in previous studies leads us to conclude that DOC export may contribute less to the carbon budget in the tropical region than has recently been supposed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
The Bay of Bengal remains one of the least studied of the world's oxygen minimum zones (OMZs). Here we offer a detailed investigation of the macrobenthos relative to oxygen minimum zone [OMZ – DO (dissolved oxygen), concentration <0.5 ml·1?1] at 110 stations off the North East Indian margin (160 and 200 N) featuring coastal, shelf and slope settings (10–1004 m). Macrobenthos (>0.5 mm) composition, abundance and diversity were studied in relation to variations in depth, dissolved oxygen, sediment texture and organic carbon. Using multivariate procedures powered by SIMPROF analysis we identified distinct OMZ core sites (depth 150–280 m; DO 0.37 ml·1?1) that exhibited dense populations of surface‐feeding polychaetes (mean 2188 ind. m?2) represented by spionids and cossurids (96%). Molluscs and crustaceans were poorly represented except for ampeliscid amphipods. The lower OMZ sites (DO > 0.55 ml·l?1) supported a different assemblage of polychaetes (cirratulids, amphinomids, eunicids, orbinids, paraonids), crustaceans and molluscs, albeit with low population densities (mean 343 ind. m?2). Species richness [E(S100)], diversity (Margalef d; H’) and evenness (J’) were lower and dominance was higher within the OMZ core region. Multiple regression analysis showed that a combination of sand, clay, organic carbon, and dissolved oxygen explained 62–78% of the observed variance in macrobenthos species richness and diversity: E(S100) and H’. For polychaetes, clay and oxygen proved important. At low oxygen sites (DO <1 ml·l?1), depth accounted for most variance. Residual analysis (after removing depth effects) revealed that dissolved oxygen and sediment organic matter influenced 50–62% of residual variation in E(S100), H’ and d for total macrofauna. Of this, oxygen alone influenced up to ~50–62%. When only polychaetes were evaluated, oxygen and organic matter explained up to 58–63%. For low oxygen sites, organic matter alone had the explanatory power when dominance among polychaetes was considered. Overall, macrobenthic patterns in the Bay of Bengal were consistent with those reported for other upwelling margins. However, the compression of faunal gradients at shallower depths was most similar to the Chile/Peru margin, and different from the Arabian Sea, where the depth range of the OMZ is two times greater. The Bay of Bengal patterns may take on added significance as OMZs shoal globally.  相似文献   

12.
Water flows, concentrations of total (TOC), dissolved (DOC), and particulate (POC) organic carbon and seston were monitored for 52 diel periods in the single creek draining a 270-ha Spartina patens-Distichlis spicata marsh on the upper Texas coast. Rainfall, creek water flows, and water levels in the creek and on the marsh were measured by recording instruments.Rainfall accounted for most marsh flooding, and water outflow was significantly correlated with both rainfall and marsh water level. Creek flows were predominantly outward because microtopographic features and dense vegetation restricted overmarsh water flows and thereby reduced tidal flooding while extending the time of precipitation runoff. Concentrations of organic carbon in water leaving the marsh were highest in spring and summer and averaged 25·62, 21·41 and 3·35 mg l?1 of TOC, DOC and POC, respectively. These were 9·34, 9·93 and 0·04 mg l?1, respectively, higher than bay water. Most POC was 0·3–28 μm in diameter. Seston > 28μ leaving the marsh was 95% amorphous material; the rest was plankton, grass particles and fecal pellets. Loss of organic carbon was directly correlated with net water flux, and thus rainfall accounted for most carbon loss. Net carbon loss averaged 196 kg TOC, 150 kg DOC and 32 kg POC per day. Net annual loss was 2·4–5·5% of net aerial primary productivity (NAPP), or 21·55-30·09 g TOC m?2 year?1.Export from this marsh falls within the range found for other marshes and the data collectively indicate that coastal marshes are not losing as much organic carbon as has been suggested by indirect measurements. The discrepancy between potential and realized export is explained by the fact that export is not a simple removal of excess detritus by tidal action but is a more complicated process mediated by the interaction of additional factors such as rainfall, vegetation structure, microtopographic variation and decomposition, which can serve to reduce the amount and quality of NAPP exported.  相似文献   

13.
In order to characterize our study area and to provide reference values to be used in the future to measure the changes produced by an increase in contamination, the concentrations of chlorinated hydrocarbons have been investigated in fifty-one samples of seawater, taken at four different depths: air-sea interface, surface, one metre and bottom waters, and in twenty-three samples of surface sediments from Blanca Bay, Argentina. Of eleven organochlorine compounds we were looking for (α BHC, lindane, heptachlor, δ BHC. aldrin, heptachlor epoxide, dieldrin, o-p′DDD, p-p′DDD, o-p′DDT and p-p′DDT), seven could be detected in seawater and three in surface sediments with the following mean concentrations: α-BHC=48·2 ng l?1; lindane=54·2 ng l?1; heptachlor=45·0 ng l?1; δ BHC=12·5 ng l?1; aldrin=61·8 ng l?1 and ΣDDT=67·0 ng l?1; and δ BHC=3·2 ng g?1; lindane=4·2 ng g?1 and heptachlor=1·0 ng g?1 for seawater, regarding the surface waters, and sediment samples, respectively.Concentration factors among the different water layers were also studied to see if there was any correlation between chlorinated hydrocarbon contents and the water depths from which the samples were taken. As a mean value, the air-sea interface water contains 18 times more of these compounds than that of the water near the bottom. A comparison of the values corresponding to seawater and surface sediments from our study area with those levels measured in samples from other geographic locations is also presented.With the purpose to detect a relationship between chlorinated hydrocarbon concentrations and the contents of particulate matter (PM) on the one hand, and particulate organic material (POM) on the other hand, four groups of samples containing different amounts of PM and POM, respectively were formed. From a comparison of the results obtained, lindane, heptachlor and δ BHC showed a tendency to lower concentrations in those samples containing little PM whereas α BHC and aldrin remained without important changes. No significant correlation was found between organochlorine levels and contents of POM.  相似文献   

14.
The concentrations of suspended matter and particulate Cd, Cu, Pb and Zn were determined for 36 samples collected at 6 stations in the Antarctic Ocean during December, 1970 and January, 1971 using membrane filters. The concentration of suspended matter was determined gravimetrically and trace metal levels were determined using anodic stripping voltammetry. For waters deeper than 100 m the concentration of suspended matter was < 100 μg l?1. Concentrations up to 542 μg l?1 were recorded between surface and 100 m. Individual concentrations of the metals were scattered with depth. Average concentrations of particulate metals were: Cd, 3.5 ng l?1; Cu, 100 ng l?1; Pb, 35 ng l?1; and Zn, 230 ng ;l?1 These measurements represent non-steady state conditions of early Antarctic summer as the ice pack disintegrates and biological activity increases.  相似文献   

15.
A fully automated method for the analysis of dissolved sulphate was tested for saline and brackish waters. A small sample volume of ? 2 ml is required, making the method very suitable for analysis of interstitial waters. The method was calibrated for samples from natural waters in the Dutch delta region, containing up to 2500 mg l?1 of sulphate, and with a salinity of 30‰.  相似文献   

16.
A new method for the determination of dissolved double-stranded deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in seawater was developed, evaluated and used to study the fates of these nucleic acids in marine ecosystems. These nucleic acids, which were pre-concentrated on a hydroxyapatite column, were determined fluorometrically by the use of ethidium bromide dye, which binds specifically to the double-stranded polynucleotide. No dissolved organic matter coexisting in the pre-concentrated sample solution interfered in the analysis of DNA and RNA. Column recoveries of DNA and RNA in a sample volume of up to 11 were 93% and 97%, respectively, and 90% of both at 51. The detection limits of DNA and RNA concentrated from a 51 sample by this fluorometric method were 0.6 and 1.1 μg l−1, respectively. The concentration of dissolved nucleic acids in the waters from Tokyo Bay and Sagami Bay showed great variation in space and time. DNA ranged from 1 to 32 μg l−1, and RNA from below the detection limit to 34 μg l−1. The total amount of phosphorus in nucleic acids was an important fraction (12.9 ± 8.2%) of the dissolved organic phosphorus (DOP) and showed a good correlation with DOP.  相似文献   

17.
A procedure is described which adds a hydrolysis step to the Johnson and Sieburth 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) assay for total dissolved monosaccharides. The advantages of the monosaccharide test are retained in the total carbohydrate test, giving nearly equivalent responses for a variety of combined carbohydrates. A total sample of 50 ml is adequate for both total carbohydrate and monosaccharide assays which permit the estimation of polysaccharide by difference. Values for Narragansett Bay and adjacent waters ranged from 452 to 2023 μg l?1 for total dissolved carbohydrate, 272 to 1353 μg l?1 for polysaccharide, and 153 to 814 μg l?1 for monosaccharide, which accounted for 6–18%, 4–13%, and 2–5% of the total dissolved carbon, respectively. We suggest that this is a sensitive and precise procedure which will be useful for investigating the distribution of dissolved carbohydrates in seawater and factors which affect its production, distribution and utilization.  相似文献   

18.
A modified version of the Coomassie Brilliant Blue dye binding protein assay has been developed for oceanographic samples and intercalibrated with the widely used Lowry assay. Particulate protein measurements were made at seven stations in the Gulf of Maine using the method. Measurements were made on cell-free homogenates. Protein concentration ranged from 2 to 212 μg l?1 (0.02–0.68 μg at N l?1) and averaged 58 μg l?1. ETS activity, chlorophyll and particulate nitrogen were significantly correlated with protein concentrations.  相似文献   

19.
Saldanha Bay is a narrow-mouth bay on the west coast of South Africa linked to the southern Benguela upwelling system. Bay productivity was investigated by use of the conventional light-and-dark bottle oxygen method, and, for comparison, through assimilation of the stable isotope tracer 13C. Gross community production GCP and net community production NCP, as determined from the oxygen method, were respectively 2.6 and 2.4 times higher than estimates determined from the stable isotope method. Chlorophyll a (Chl a) concentrations increased with the onset of spring and well-defined subsurface maxima developed in association with increasingly stratified conditions (mean water column Chl a concentrations ranged from 5.4 to 31.5?mg m?3 [mean 15.5?mg m?3; SD 7.6]). A sharp decline in photosynthetic rates P* (GCP normalised to Chl a concentration) with depth was attributed to light limitation, as demonstrated by the high vertical attenuation coefficients for downward irradiance Kd, which varied from 0.29 to 0.70?m?1 (mean 0.48?m?1; SD 0.12). Productivity maxima were consequently near-surface despite the presence of deeper subsurface biomass maxima. The community compensation depth Zcc, where gross community production balances respiratory carbon loss for the entire community, ranged from 2.9 to 9.2?m (mean 5.8?m; SD 2.2), and was typically shallower than the 1% light depth for PAR (photosynthetically available radiation), Z1%PAR, which is traditionally assumed to be the depth of the euphotic zone and which ranged from 6.6 to 15.9?m (mean 9?m; SD 2.6). Autotrophic communities, where organic matter is produced in excess of respiratory demand, were confined on average to the upper 5.8?m of the water column, and often excluded the bulk of the phytoplankton community, where light limitation is considered to lead to heterotrophic community metabolism. Estimates of integrated water column productivity ranged from 0.84 to 8.46?g C m–2 d?1 (mean 3.35?g C m?2 d?1; SD 1.9).  相似文献   

20.
海水中溶解有机碳(DOC)的测定方法主要有过硫酸盐氧化法;紫外光氧化法和高温氧化法。近年来,随着仪器分析的进步,国外已出现能自动连续测定DOC的商售设备。 Menzel等发展的过硫酸钾氧化法,由于设备简单,容易实施,至今仍为很多人采用。  相似文献   

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