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1.
Observations of the short-term changes of seawater bacterioplankton were carried out during the summer of 1988 in Antarctic coastal surface waters. The studies were designed to compare the variations of bacterioplankton in freemoving and enclosed seawater. Even when a diurnal cycle is present the data collected from the enclosed seawater experiments remain much more constant than the corresponding data in free-moving seawater. The wide range of parameters used in the two experiments reveals common properties which illustrate the major role of displacements of water masses at a fixed sampling station in the temporal changes observed in free-moving Antarctic coastal seawater.  相似文献   

2.
The purpose of this study was to assess the differences in the abundance and activity of the bacterioplankton at sites with varied boating activity, and to determine the response of the communities to additional petroleum pollution. Three sites, including two marinas and a site on Bogue Sound in coastal North Carolina, were selected for monthly experiments. Seasonal patterns of bacterioplanktonic abundance and diesel fuel biodegradation for each site were examined, and possible correlations with intensity of boating activities were explored. Bacterioplanktonic communities at the three sites in this study were more similar in their structure and biodegradation potential than would have been expected from previous studies. We found no differences in the abundance and biodegradation potential of theses communities at the three sites, and only a slightly elevated number of hydrocarbon degraders at one of the marinas. Patterns of biodegradation were more closely related to total bacterial abundance, rather than number of petroleum hydrocarbon degraders. There was a strong seasonal pattern in bacterial abundance and biodegradation at all three sites. The bacterioplanktonic Community at all sites responded similarly to additions of diesel fuel. Bacterial abundance and productivity were both elevated to some extent, and number of petroleum hydrocarbon degraders changed relatively little. These data indicate that marinas may not profoundly after the bacterioplankton and that coastal waters often have resident bacterial communities capable of degrading petroleum hydrocarbon pollution.  相似文献   

3.
《Marine Chemistry》2001,73(1):21-36
As part of the ANTARES 3/F-JGOFS cruise, the distributions of dissolved iron and manganese were measured in October 1995 in the north–east wake of the Kerguelen archipelago (48°40′–49°40′S, 68°70′–70°50′E), an area that shows high phytoplankton biomass (CZCS and SeaWiFS data) in the middle of the High Nutrient Low Chlorophyll (HNLC) Southern Ocean. The study area (about 25,000 km2) comprised a branch of the Polar Front with Antarctic surface water (AASW) intruding northward, shouldering the shelf break of the Kerguelen Plateau. The coastal zone was clearly affected by material of lithogenic origin (riverine discharges, soil leaching by rain waters, aeolian inputs), as well as by inputs from the sediments (effluxes from the sediment–water interface, resuspension from the sediments), its near surface waters showing considerable enrichment in dissolved iron (5.3–12.6 nM) and in dissolved manganese (2.9–8.6 nM). The offshore waters, although less enriched in trace-metals, were also affected by trace-metal inputs from coastal and continental shelf origin. Dissolved iron and manganese concentrations in these waters were 0.46–0.71 and 0.68–1.3 nM, i.e. far over typical antarctic open ocean surface water concentrations of 0.16 nM for iron [Martin, J.H., Gordon, R.M., Fitzwater, S.E., 1990. Iron in Antarctic waters. Nature, 345: 156–158.] and around 0.1 nM for manganese [Martin, J.H., Gordon, R.M., Fitzwater, S.E., 1990. Iron in Antarctic waters. Nature, 345: 156–158; Sedwick, P.N., Edwards, P.R., Mackey, D.J., Griffiths, F.B., Parslow, J.S., 1997. Iron and manganese in surface waters of the Australian subantarctic region. Deep-Sea Res., 44: 1239–1253.]. The dissolved iron enrichment in coastal waters of the Kerguelen Islands is much more important (about 10 times for dissolved iron) than for the Galapagos Islands, another oasis in the HNLC Equatorial oceanic system, where the concentration increase in dissolved iron in the surface waters around the islands is mostly driven by upwelling of the Equatorial Under Current (EUC) as it reaches the Galapagos Platform.  相似文献   

4.
Photochemical production rates and steady-state concentrations of the highly reactive OH radical were determined in Antarctic seawater in the Weddell-Scotia Confluence during the austral spring of 1993 and along the Antarctic Peninsula during the austral summer of 1994. OH radical photoproduction rates were 30±2 nM/day and 46±2 nM/day in surface open oceanic and coastal waters, respectively. Corresponding steady-state concentrations were 2.6×10−19 and 4.3×10−19 M which are similar to those found in tropical latitudes. In-situ irradiation experiments (drifter deployments) at different depths in the upper water column indicated that multiple sources for the OH radical existed at three Antarctic stations. Ultrafiltration studies and model calculations based on wavelength-dependent OH radical quantum yields indicated that the main sources were photochemical reactions of low molecular weight dissolved organic matter (DOM), nitrate, and nitrite. Production of the OH radical from nitrate photolysis was almost exclusively UV-B dependent, while OH radical production from nitrite photolysis was mainly UV-A dependent. OH production from DOM photolysis was both UV-A and UV-B dependent. In the upper few meters at open oceanic sites, nitrate and DOM were the dominant OH radical sources, while deeper in the water column DOM and nitrite were important because of the greater importance of UV-A with depth. During non-ozone hole conditions, nitrate contributed about 33%, while DOM plus nitrite contributed about 67% of the predicted OH radical production in open oceanic surface waters. During an ozone hole (151 Dobson units), the corresponding percentages changed to about 40 and 60% for nitrate and DOM due to the higher UV-B irradiance. Model calculations predict that during an ozone hole (151 Dobson units), OH radical production in surface waters will be enhanced by at least 20%, mostly from nitrate photolysis and to a lesser extent from DOM photochemical reactions. This study indicates that ozone hole events significantly increase OH radical production, as well as the photolysis of DOM, in Antarctic waters, and that rates can be as high or higher than those at lower latitudes, especially if differences in temperature and solar irradiance are taken into account.  相似文献   

5.
A study was carried out to assess primary production and associated export flux in the coastal waters of the western Antarctic Peninsula at an oceanographic time-series site. New, i.e., exportable, primary production in the upper water-column was estimated in two ways; by nutrient deficit measurements, and by primary production rate measurements using separate 14C-labelled radioisotope and 15N-labelled stable isotope uptake incubations. The resulting average annual exportable primary production estimates at the time-series site from nutrient deficit and primary production rates were 13 and 16 mol C m−2, respectively. Regenerated primary production was measured using 15N-labelled ammonium and urea uptake, and was low throughout the sampling period.The exportable primary production measurements were compared with sediment trap flux measurements from 2 locations; the time-series site and at a site 40 km away in deeper water. Results showed ∼1% of the upper mixed layer exportable primary production was exported to traps at 200 m depth at the time-series site (total water column depth 520 m). The maximum particle flux rate to sediment traps at the deeper offshore site (total water column depth 820 m) was lower than the flux at the coastal time-series site. Flux of particulate organic carbon was similar throughout the spring–summer high flux period for both sites. Remineralisation of particulate organic matter predominantly occurred in the upper water-column (<200 m depth), with minimal remineralisation below 200 m, at both sites. This highly productive region on the Western Antarctic Peninsula is therefore best characterised as ‘high recycling, low export’.  相似文献   

6.
Calcium in sea water was determined of the samples taken from the Antarctic and Indian Oceans. Surface water commonly contains less calcium relative to chlorinity than does deep water. The tendency, however, is very faint in the Antarctic Ocean. In the surface waters, the Ca/Cl ratio is lower in the tropical and subtropical waters and the ratio well correlates with phosphate. The Ca/P ratio is calculated as 37 in atomic ratio. These may indicate that calcium is uptaken by organisms to make skeletal parts from surface water which is supersaturated with respect to calcite or aragonite. On the other hand, no definite correlationship between calcium and phosphate is found in subsurface water. This fact suggests that the regeneration process of calcium from organic debris is different from that of phosphate. The increase-rate of calcium in the abyssal water is estimated to be 0.18g at./(1 yr), which is due to the dissolution of calcium carbonate. The rate is about a half of total carbonate increase in the water.  相似文献   

7.
Water column samples have been collected in the outer channel of the Ferrol Ria (NW Spain) during four occasions over a tidal cycle. The objective was to study the exchange of dissolved and particulate Cd, Cu, Pb and Zn and particulate Al, Fe and Si between the ria and the adjacent coastal waters. This study provides the first extensive dataset on dissolved and particulate metal concentrations in the water column of a Galician ria. Typical concentrations of dissolved Cd (96 ± 31 pM), Cu (8 ± 4 nM), Pb (270 ± 170 pM) and Zn (21 ± 10 nM) were similar than in other European Atlantic shelf and coastal waters. The fraction of metals in the particulate phase followed the trend: Pb > Cu Zn > Cd. The outgoing water from the ria was enriched in dissolved and particulate Cu, Pb and Zn compared with incoming waters, whereas Cd concentrations were similar for both waters. The suspended particulate matter was composed of a mixture of marine and continental material. The latter end-member was found to arise from the metal-rich ria bed sediments, which is diluted by the dominant metal-poor marine end-member. The net output flux of Cu from the channel is balanced by the freshwater inputs to the ria, and the net Zn flux gave a positive output to coastal waters. For Pb, the net flux to the coastal waters is less than that input from the rivers, as a result of its particle reactivity and deposition in sediments. On the contrary, a net input flux of dissolved Cd from coastal waters was observed, highlighting the oceanic source of this metal in the Galician rias. Results from the budget calculations are in agreement with the differential geochemical behavior of these elements in coastal waters.  相似文献   

8.
The knowledge of chlorofluorocarbon (CFC11, CFC12) concentrations in ocean surface waters is a prerequisite for deriving formation rates of, and water mass ages in, deep and bottom waters on the basis of CFC data. In the Antarctic coastal region, surface-layer data are sparse in time and space, primarily due to the limited accessibility of the region. To help filling this gap, we carried out CFC simulations using a regional ocean general circulation model (OGCM) for the Southern Ocean, which includes the ocean–ice shelf interaction. The simulated surface layer saturations, i.e. the actual surface concentrations relative to solubility-equilibrium values, are verified against available observations. The CFC surface saturations driven by concentration gradients between atmosphere and ocean are controlled mainly by the sea ice cover, sea surface temperature, and salinity. However, no uniform explanation exists for the controlling mechanisms. Here, we present simulated long-term trends and seasonal variations of surface-layer saturation at Southern Ocean deep and bottom water formation sites and other key regions, and we discuss differences between these regions. The amplitudes of the seasonal saturation cycle vary from 22% to 66% and their long-term trends range from 0.1%/year to 0.9%/year. The seasonal surface saturation maximum lags the ice cover minimum by two months. By utilizing observed bottle data the full seasonal CFC saturation cycle can be determined offering the possibility to predict long-term trends in the future. We show that ignoring the trends and using instead the saturations actually observed can lead to systematic errors in deduced inventory-based formation rates by up to 10% and suggest an erroneous decline with time.  相似文献   

9.
A down-scaled operational oceanographic system is developed for the coastal waters of Korea using a regional ocean modeling system(ROMS).The operational oceanographic modeling system consists of atmospheric and hydrodynamic models.The hydrodynamic model,ROMS,is coupled with wave,sediment transport,and water quality modules.The system forecasts the predicted results twice a day on a 72 h basis,including sea surface elevation,currents,temperature,salinity,storm surge height,and wave information for the coastal waters of Korea.The predicted results are exported to the web-GIS-based coastal information system for real-time dissemination to the public and validation with real-time monitoring data using visualization technologies.The ROMS is two-way coupled with a simulating waves nearshore model,SWAN,for the hydrodynamics and waves,nested with the meteorological model,WRF,for the atmospheric surface forcing,and externally nested with the eutrophication model,CE-QUAL-ICM,for the water quality.The operational model,ROMS,was calibrated with the tidal surface observed with a tide-gage and verified with current data observed by bottom-mounted ADCP or AWAC near the coastal waters of Korea.To validate the predicted results,we used real-time monitoring data derived from remote buoy system,HF-radar,and geostationary ocean color imager(GOCI).This down-scaled operational coastal forecasting system will be used as a part of the Korea operational oceanographic system(KOOS) with other operational oceanographic systems.  相似文献   

10.
Salt marsh soils from the mean water level and from different levels above the mean water level at two Danish coastal lagoons, which differ in water pollution due to differences in the character of the surrounding land use, were analysed for EDTA extractable Pb, Cu, Zn and Ni and for organic matter and cation exchange capacity. From the results a positive correlation was apparent between the trace metal loading of the soils, expressed by the trace metal concentration in relation to the content of soil organic matter, and the mean trace metal concentration of the lagoon water, submerging the salt marsh at high water. This opens up the possibility of using analyses of salt marsh soils in the indication of trace metal pollution of protected coastal waters.  相似文献   

11.
This study examined seasonal and annual occurrences of warm oceanic tintinnid species in southern Korea coastal waters. The indicative species of tintinnids was monitored using three approaches: monitoring from cruises traveling from the warm pool in the western North Pacific to the Korea Strait; biweekly or monthly monitoring in the Korea Strait; and daily monitoring in the nearshore water. Annual pulses of warm oceanic indicator species were regularly observed in the Korea Strait. In September 2008 recorded a maximum species number of warm water indicators, a representative species for warm oceanic waters, Climacocylis scalaroides was simultaneously detected in the nearshore water as well as the Korea Strait. The result indicates that the greater warm water extension into Korean coastal areas was in September 2008. Sharp declines in species diversity were observed in the transitional area between neritic and Kuroshio zone in East China Sea (ECS). Epiplocyloides reticulata, reported previously as a Kuroshio indicator, was considered an ECS indicator species, as it was undetected in the western North Pacific central zone but was found abundantly in the ECS. Tintinnid species can be used as biological indicators to detect the inflow of warm oceanic waters into Korean coastal waters.  相似文献   

12.
通过对2010/2011年夏季南极长城湾叶绿素a浓度和海流等环境参数的传感器连续观测;研究其时空变化特征及海流对浮游植物生物量的影响。结果表明;12.9 m水层叶绿素a浓度从12月中旬开始增长;直至2月上旬开始维持相对稳定;期间出现两个高值点(2.74 μg/L和3.76 μg/L)。叶绿素a浓度表现出了24 h周期变化特征;每日叶绿素a浓度最高值出现在正午前后时段的概率要高于其他时段。表层海水受西北风影响;流速较大;约为60~100 cm/s;中层和底层水体流速较小;约为10 cm/s。表层的风海流使海水在长城湾发生辐散;下层海水向上涌升;驱动了水体的垂直交换。长城湾与麦克斯韦尔湾存在水体交换;水体主要从中层进入湾内;从表层输出。长城湾的叶绿素a浓度与流速呈显著负相关;表明低流速环境有利于长城湾浮游植物的生长。  相似文献   

13.
My studies on metabolism of organic matter in aquatic environments first involved research on the sedimentation process of organic matter in lacustrine environments. Subsequently, measurements of primary production in lake and sea water were undertaken to know the organic substance supply into the metabolism. After establishing the routine technique of productivity measurement in aquatic environment, the primary production and the photosynthetic characteristics in waters in the northwestern Pacific, the western Indian Ocean and the Antarctic Sea were studied. Following the development of new methods to determine the organic substances in the dissolved and particulate forms and chlorophyll pigment in seawater, their distributions both horizontal and vertical directions were determined. And I have had interest in the mechanism producing a subsurface chlorophyll maximum in the ocean. Recently, my major interest has been directed to the coastal waters. The nitrogen cycle was studied in oyster beds and the research on eutrophication processes in a shallow bay is being carried out from the aspect of production and decomposition of organic matter.  相似文献   

14.
During the first year of the Northeast Pacific GLOBEC program we examined the spatial distributions of dissolved and particulate organic carbon and nitrogen in the surface waters off the Oregon and Washington coasts of North America. Eleven east–west transects were sampled from nearshore waters to 190 km offshore. Hydrographic data and the distribution of inorganic nutrients were used to characterize three distinct water sources: oligotrophic offshore water, the Columbia River plume, and the coastal upwelling region inshore of the California Current. Warm, high salinity offshore water had very low levels of inorganic nutrients, particulate organic carbon (POC) and dissolved organic carbon (DOC). Warm, low salinity water in the Columbia River plume was relatively low in nitrate, but showed a strong negative correlation between salinity and silicate. The river plume water had the highest levels of total organic carbon (TOC) (up to 180 μM) and DOC (up to 150 μM) observed anywhere in the sampling area. Cold, high salinity coastal waters had high nutrient levels, moderate to high levels of POC and particulate organic nitrogen (PON), and low to moderate levels of DOC and dissolved organic nitrogen (DON). Each of these regions has characteristic C:N ratios for particulate and dissolved organic material. The results are compared to concentrations and partitioning of particulate and dissolved organic carbon and nitrogen in other regions of the North Pacific and North Atlantic Oceans.  相似文献   

15.
Coastal environments are increasingly under threat from multiple stressors and pressure from human activities across the land-sea interface. Managing these pressures from people requires, more than ever, understanding what is at stake in terms of the benefits and values associated with coastal waters. This article presents the results of a choice experiment which was designed to elicit society׳s willingness to pay in the context of economic and environmental trade-offs people to improve coastal water quality. The study site is a coastal Australian city, Adelaide, South Australia. The city discharges a large proportion of its stormwater and treated wastewater to the coastal waters of Gulf St Vincent. Willingness to pay for a package of improvements to urban water management is considerable. A mix of projects that restores 25 days per year of water clarity, seagrass area from 60% to 70% of the original area and five reef areas is worth $AUS67.1 M to households in the Adelaide metropolitan area. The results can inform public policy discussions including the cost-benefit analysis of different water management strategies including investments in urban infrastructure.  相似文献   

16.
The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (?65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.  相似文献   

17.
Seasonal changes of tide signal(s), temperature, salinity and current were studied during the years 2004-2005 in the northernmost Gulf of Aqaba, which is under developmental activities, to obtain scientific bases for best management and sustainability. Spectrum analysis revealed permanent signals of tide measurements during all seasons, which represented semidiurnal and diurnal barotropic tides. The other signal periods of 8.13, 6.10-6.32, 4.16 and 1.02-1.05 h were not detected in all seasons, which were related to shallow water compound and overtides of principle solar and lunar constituent and to seiches generated in the Red Sea and the Gulf of Aqaba. Spatial and temporal distribution of temperature, salinity and density showed significant differences between months in the coastal and offshore region and no significant differences among the coastal sites, between the surface and bottom waters and between coastal and offshore waters. Therefore, the temporal and spatial variation of water properties in the northernmost Gulf of Aqaba behave similarly compared to other parts. The coastal current below 12 m depth was weak (3-6 cms-1) and fluctuated from east-northeastward to west-southwestward (parallel to the shoreline), which may be related to the effect of bottom topography and/or current density due to differential cooling between eastern and western parts in the study area, and windinduced upwelling and downwelling in the eastern and western side, respectively. The prevailing northerly winds and stratification conditions during summer were the main causes of the southward current at 6 and 12 m depths with average speed of 28 and 12 cms-1, respectively.  相似文献   

18.
作者基于2011年9月(丰水期)和2012年1月(枯水期)粤西近岸30米以浅海域的调查资料,分析该海域浮游植物的种类组成、优势种、丰度及其群落结构多样性。结果表明,调查海域共鉴定浮游植物4门41属116种,硅藻为最主要优势类群。丰水期与枯水期共有种类40种,物种相似性指数为34.48%,表明2个调查季节种类组成变化较大,存在明显的季节性差异。枯水期优势种仅1种,为金藻门(Chrysophyta)的球形棕囊藻(Phaeoecystis globosa),优势度高达0.496;丰水期优势种有4种,其中以硅藻门的旋链角毛藻(Chaetoceros curvisetus)优势度较高(0.249)。浮游植物丰度表现出时间和空间异质性,丰度总体呈现近岸站位高于离岸站位,此外,丰水期浮游植物丰度湛江沿岸站位高于其他调查站位,枯水期浮游植物丰度则由西南部向东北部递减,总体而言,枯水期浮游植物丰度比丰水期高。群落结构多样性为枯水期西南部海域明显低于东北部海域,丰水期站位间多样性无明显变化规律,相比之下,丰水期群落物种多样性水平相对较高。相关分析表明:浮游植物丰度与p H、悬浮物呈正相关,与丰水期水温和枯水期盐度呈负相关。  相似文献   

19.
Variations of temperature and salinity were observed off the Otago Peninsula from October 1966 to December 1967. In‐shore temperatures were more variable than those seawards and variability decreased with increasing depth. Temperatures over the continental shelf and down to 200 m in the open sea varied seasonally. Below 200 m temperature variations were small and non‐seasonal. Salinities were depressed in the shallow coastal waters by land run‐off, this tendency being more pronounced in autumn and winter. Seawards of this coastal zone seasonal variations of salinity were small. Over the outer shelf a zone of higher salinities was always present. Beyond this zone salinities decreased with increasing distance from shore and with increasing depth. A salinity minimum was sometimes present between 500 and 1,000 m.

Although the upper 200 m were seasonally stratified, the same water masses could always be recognised. Two water masses were present near the surface, the Southland Current, here interpreted as being subtropical in origin, being located in shore of Subantarctic Surface Water. These two water masses are separated by the clearly defined Southland Front. Along the shore, neritic conditions develop through modification of Southland Current water by coastal and climatic effects. Seawards, beneath Subantarctic Surface Water, the core of Antarctic Intermediate Water could sometimes be recognised as a salinity minimum.  相似文献   

20.
基于主成分分析法的闽江口及其近岸水域水质评价   总被引:1,自引:0,他引:1  
选取2016年4月、7月和10月闽江口及其近岸水域7个调查点位的盐度、悬浮物、pH、溶解氧、化学需氧量、氮营养盐和重金属等15项监测指标数据,采取主成分分析法分析了该水域的水质,明确影响该水域水质的主要污染因子。结果表明:15项监测指标转换提取为4个主成分,解释82.153%的方差。从时间分布来看,闽江口及其近岸水域在4月份水质较差、10月份次之、7月份较好。从空间分布来看,近河口水质较差而远离河口水质较好。影响该水域污染水质的主要驱动因子是pH、COD、氮营养盐和Cd。研究结果对于进一步了解闽江口及其近岸水域水质情况具有重要意义,同时也为福建省海洋管理的科学决策提供支持。  相似文献   

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