Devenir des virus entériques en mer et influence des facteurs environnementaux     

《Oceanologica Acta》1998,21(6):983-992

To improve the knowledge of the survival of enteric viruses in a marine environment, the influence of physico-chemical parameters (temperature, UV, salinity) on the survival of infectious poliovirus 1 and hepatitis A virus (HAV) in seawater was first studied, the influence of suspended solids (SS) on poliovirus adsorption and survival in seawater was then evaluated and the detection of rotavirus genome in environmental samples (shellfish, river water, treated wastewater) was finally investigated. The results show that temperature has a major impact on virus survival in seawater as the time necessary to inactivate 90 % of the virus (T₉₀) is 671 days at 4 °C and only 25 days at 25 °C. Ultraviolet light (42 mW s cm⁻²) rapidly inactivates viruses but HAV is more resistant (T₉₀ = 2.6 min) than the poliovirus 1 (T₉₀ = 1.3 min). By contrast, seawater salinity has no effect on virus survival. In presence of SS, 90 % to 99.9 % of the viruses were adsorbed. This adsorption does not provide any protection for viruses with low SS concentrations (3 and 15 mg L⁻¹) but a slight increase in virus survival was observed with a high SS concentration (500 mg L⁻¹). Finally environmental sample analysis indicated that 20 % shellfish, about 40 % river water and 40 % treated wastewater tested positive for the rotavirus genome.  相似文献   

Influence of water column dynamics on sulfide oxidation and other major biogeochemical processes in the chemocline of Mariager Fjord (Denmark)     

《Marine Chemistry》2001,74(1):29-51

Major electron donors (H₂S, NH₄⁺, Mn²⁺, Fe²⁺) and acceptors (O₂, NO₃⁻, Mn(IV), Fe(III)), process rates (³⁵SO₄²⁻ reduction, dark ¹⁴CO₂ fixation) and vertical fluxes were investigated to quantify the dominant biogeochemical processes at the chemocline of a shallow brackish fjord. Under steady-state conditions, the upward fluxes of reductants and downward fluxes of oxidants in the water column were balanced. However, changes in the hydrographical conditions caused a transient nonsteady-state at the chemocline and had a great impact on process rates and the distribution of chemical species. Maxima of S⁰ (17.8 μmol l⁻¹), thiosulfate (5.2 μmol l⁻¹) and sulfite (1.1 μmol l⁻¹) occurred at the chemocline, but were hardly detectable in the sulfidic deep water. The distribution of S⁰ suggested that the high concentration of S⁰ was (a) more likely due to a low turnover than a high formation rate and (b) was only transient, caused by chemocline perturbations. Kinetic calculations of chemical sulfide oxidation based on actual conditions in the chemocline revealed that under steady-state conditions with a narrow chemocline and low reactant concentrations, biological sulfide oxidation may account for more than 88% of the total sulfide oxidation. Under nonsteady-state conditions, where oxic and sulfidic water masses were recently mixed, resulting in an expanded chemocline, the proportion of chemical sulfide oxidation increased. The sulfide oxidation rate determined by incubation experiments was 0.216 μmol l⁻¹ min⁻¹, one of the highest reported for stratified basins and about 15 times faster than the initial rate for chemical oxidation. The conclusion of primarily biological sulfide oxidation was consistent with the observation of high rates of dark ¹⁴CO₂ fixation (10.4 mmol m⁻² day⁻¹) in the lower part of the chemocline. However, rates of dark ¹⁴CO₂ fixation were too high to be explained only by lithoautotrophic processes. CO₂ fixation by growing populations of heterotrophic microorganisms may have additionally contributed to the observed rates.  相似文献   

Environmental tolerances of the beach-hopper Orchestia gammarellus (Pallas) (Crustacea:Amphipoda)     

《Marine environmental research》1986,19(2):115-129

Orchestia gammarellus (Pallas) will tolerate temperatures from 0°C to c. 30°C but dies in < 1 h at 35°C. Both small and large animals survive > 96 h in water (aerated) between 1 and 60%(.) salinity. In distilled water and 100%(.) brine death occurred after 8–24 h. In fully saline water, pH reduction to c. 3·3 is tolerated. Highly alkaline (pH 11–13) conditions in low salinity media are rapidly fatal. Ammonium concentrations (in fully saline water) some five orders of magnitude higher than normal for seawater are tolerated, reflecting the enhanced ammonium concentration encountered in rotting weed beds. Cl⁻ ion concentration equivalent to that in normal seawater will not support O. gammarellus in the absence of Na⁺ ions. High NO₃⁻ concentrations (> 100 mg NO₃⁻ litre⁻¹) are fatal in < 24 h. A large range of NaCl concentrations is tolerated (one to two orders of magnitude dilution) by immersed animals. Animals will live longer in air, however, when fed low Na⁺ food than when immersed in seawater diluted to an equivalent ion strength. Ca²⁺ and K⁺ ions cannot substitute for Na⁺. Orchestia gammarellus will, however, tolerate wide variations in the ratio of Na⁺:K⁺ ions (i.e to a shift from 30:1 to 0·3.1) in hypo-osmotic media. At 10°C it will survive c. 5 h of anoxia. It will penetrate into strongly reducing conditions (− 318 mV) even with access to better oxygenated conditions. In nature, behavioural avoidance probably ensures that O. gammarellus does not encounter many of these parameters at acutely limiting values. That this species is so tolerant, however, bears on the evolutionary adaptability of talitrid amphipods to non-marine conditions. Desiccation sensitivity and Na⁺ ion dependency are the species' most important barriers to life on land.  相似文献   

Cadmium toxicity to three species of estuarine invertebrates     

Gerald G. Pesch  Nelson E. Stewart 《Marine environmental research》1980,3(2):145-156

Three species of estuarine invertebrates, Palaemonetes pugio (grass shrimp), Pagurus longicarpus (hermit crab) and Argopecten irradians (bay scallop), were exposed to Cd in flowing seawater at concentrations of 0·06, 0·12, 0·25, 0·5 and 1·0 mg/litre. Incipient LC₅₀ values of 0·53 and 0·07 mg/litre were estimated for bay scallop and hermit crab, respectively. The toxicity curve for grass shrimp had not stabilised, but the incipient LC₅₀ value was estimated to fall within a range of 0·2 to 0·3 mg/litre. Short-term response, as measured by time to 50% mortality at the highest Cd concentration, was 10, 21 and 23 days for the bay scallop, hermit crab and grass shrimp, respectively. Scallop growth was inhibited at all exposure concentrations with a measured 42-day EC₅₀ value of 0·078 mg/litre Cd. Byssal thread detachment precedes death in bay scallops. An EC₅₀ value of 0·54 mg/litre Cd for byssal detachment was measured on day 8 of the bioassay before appreciable mortality. This compared favourably with the incipient LC₅₀ value of 0·53 mg/litre Cd. Cadmium accumulation occurred at all concentrations in bay scallop and grass shrimp.  相似文献   

Contrasting food-web support bases for adjoining river-influenced and non-river influenced continental shelf ecosystems     

《Estuarine, Coastal and Shelf Science》2005,62(1-2):55-62

Nutrient and chlorophyll a concentrations and distributions in two adjoining regions of the South Atlantic Bight (SAB), Onslow Bay and nearshore Long Bay, were investigated over a 3-year period. Onslow Bay represents the northernmost region of the SAB, and receives very limited riverine influx. In contrast, Long Bay, just to the south, receives discharge from the Cape Fear River, draining the largest watershed within the State of North Carolina, USA. Northern Long Bay is a continental shelf ecosystem that has a nearshore area dominated by nutrient, turbidity and water-color loading from inputs from the river's plume. Average planktonic chlorophyll a concentrations ranged from 4.2 μg l⁻¹ near the estuary mouth, to 3.1 μg l⁻¹ 7 km offshore in the plume's influence, to 1.9 μg l⁻¹ at a non-plume station 7 km offshore to the northeast. Average areal planktonic chlorophyll a was approximately 3X that of benthic chlorophyll a at plume-influenced stations in Long Bay. In contrast, planktonic chlorophyll a concentrations in Onslow Bay were normally <0.50 μg l⁻¹ at a nearshore (8 km) site, and <0.15 μg l⁻¹ at sites located 45 and 100 km offshore. However, high water clarity (K_PAR 0.10–0.25 m⁻¹) provides a favorable environment for benthic microalgae, which were abundant both nearshore (average 58.3 mg m⁻²) and to at least 45 km offshore in Onslow Bay (average 70.0 mg m⁻²) versus average concentrations of 10–12 mg m⁻² for river-influenced areas of Long Bay. This provides evidence that much of the inner shelf food web in Onslow Bay is based on benthic microalgal production, in contrast to a plankton-based food web in northern Long Bay and more southerly areas of the SAB.  相似文献   

Coulometric total carbon dioxide analysis for marine studies: Automation and calibration     

《Marine Chemistry》1987,21(2):117-133

An automated instrument for the coulometric detection of total carbon dioxide (TCO₂) was developed from the manual prototype of Johnson et al. Pure CO₂ was used to calibrate the detector, the whole analytical procedure was controlled by a microcomputer, and the unit was compact enough for field and shipboard use. Some 67 samples from the Askö field station on the Baltic Sea (salinity = 6; TCO₂ ranging from 1224.3 to 1276.1 μmol l⁻¹ with a mean of 1245.6 μmol l⁻¹) and 31 samples from Swedish lakes (TCO₂ ranging from 19.5 to 252.3 μmol l⁻¹ with a mean of 72.9 μmol l⁻¹) were analyzed. The pooled standard deviation of these analyses was ± 1.0 μmol l⁻¹ (% CV of 0.08 and 1.3%, respectively). Precisions of < 0.1% were routine for waters exceeding 1000 μmol l⁻¹ TCO₂. At Askö on the Baltic Sea, the mean absolute difference between coulometric and pH-alkalinity determinations of TCO₂ on 22 parallel samples was 6.7 μmol kg⁻¹ or 0.5% of the mean. Community metabolism studies gave maximum rates of net production (TCO₂ uptake) and respiration (TCO₂ production) of 0.9-1.2 and 0.3-0.5 μmol l⁻¹ b⁻¹, respectively. The results of this study provide solutions to the problems observed with the earlier manual prototype.  相似文献   

Mercury in the Southern North Sea and Scheldt estuary     

《Marine Chemistry》2001,75(3):229-248

Dissolved and particulate mercury and methylmercury concentrations were determined in the Southern Bight of the North Sea and the Scheldt estuary in the period 1991–1999. Mercury and methylmercury concentrations are higher before 1995 than after 1995, especially in the fluvial part.The North Sea: In the offshore stations, dissolved Hg concentrations are generally higher in winter than in summer while the reverse is true for particulate Hg K_D values (K_D=the concentration of particulate Hg (Hg_P in pmol kg⁻¹) divided by the concentration of dissolved Hg (Hg_D in pmol l⁻¹)) range from 100,000 to 1000,000 l kg⁻¹. Dissolved methylmercury concentrations vary from 0.05 to 0.25 pmol l⁻¹ in summer and from d.l. to 0.23 pmol l⁻¹ in winter and particulate methylmercury concentrations from 1.8 to 36 pmol g⁻¹ in summer and from 0.9 to 21 pmol g⁻¹ in winter. The K_D ranges from 9,000 to 219,000 l kg⁻¹.The Scheldt estuary: In winter, dissolved Hg concentrations are elevated in the upper estuary, decrease exponentially in the low salinity range followed by a very slow decrease towards the mouth. In summer, they are low in the fluvial part, increase in the low salinity range or in the mid-estuary and sometimes show an increase in the lower estuary. Particulate Hg concentrations do not show any seasonal trend.Dissolved MMHg concentrations are much lower in winter, when maximum concentrations are found in the upper estuary, than in summer. In summer, the MMHg concentrations are low at low salinity, they show a first increase in the salinity range from 3 to 12, a decrease in the mid-estuary and a second increase in the lower estuary.The highest particulate MMHg concentrations are found in the upper estuary, while in the lower estuary generally lower and more constant values are observed. The ratio of dissolved MMHg to dissolved Hg (cruise averages between 1.3% and 20%), is higher than the ratio of particulate MMHg to particulate Hg (cruise averages of 0.27–0.90%). The K_D values for MMHg are lower in the summer (30,000–65,000) than in autumn and winter (77,000–114,000).The Scheldt river: In the fluvial part of the Scheldt, dissolved increases in the most upstream stations, while particulate Hg shows no particular pattern. Dissolved MMHg ranges from 0.1 to 0.39 pmol l⁻¹ and particulate MMHg from 3.1 to 43.5 pmol g⁻¹. The MMHg concentrations are comparable to those found in the estuary and no seasonal variations could be observed.  相似文献   

Rock phosphate: The source of mercury pollution in a marine ecosystem at Albany,Western Australia     

《Marine environmental research》1986,18(3):185-202

Mercury (Hg) is present in rock phosphate as a trace element (< 0·6 mg kg⁻¹). It has been established that some of this Hg was liberated, during fertilzer manufacture, into scrubber fluids. These were subsequently, discharged to Princess Royal Harbour, Albany, at a rate of about 14 kg Hg per annum between 1970 and 1983.This resulted in Hg pollution of sediments (< 1·7mg kg⁻¹), molluscs (< 50 mg kg⁻¹ wet weight) and demersal and pelagic fish (< 7·6 mg kg⁻¹ wet weight). Corrective action has been taken to stop the discharge and to protect consumers of fish from the area.  相似文献   

The effect of salinity on the microbial mineralization of two polycyclic aromatic hydrocarbons in estuarine sediments     

《Marine environmental research》1988,26(3):181-198

Sediments from the lower Hudson River estuary and two other coastal environments were examined experimentally for their ability to mineralize (convert to CO₂) the polycyclic aromatic hydrocarbons (PAHs) naphthalene and anthracene over a range of salinities. Routine assays employed 1:1 (vol fresh sed:vol water) sediment slurrys in order to overcome natural variability in mineralization rates among replicates. Mineralization rates were stimulated by about 2·5 fold, compared to unslurried controls, while the coefficient of variation fell from 13% to 3·5%.Rates of naphthalene mineralization in surface sediments from along the mainstem of the Hudson River (salinities from 2 to 27%) ranged from 0·011 to 1·5 nmol cm⁻³ day⁻¹ (pool turnover [T_n] from 60 to 2040 days) with no discernible trends along the estuarine gradient. For two stations examined experimentally (mile point 5, salinity 23%; mile point 26, salinity 5%), microbial assemblages appeared acclimated to broad salinity variations as alter rates of mineralization compared to controls.Sediments from two upstream marshes of the Hudson (mile points 36 and 45) showed rates of naphthalene mineralization from 0·007 to 0·15 nmol cm⁻³ day⁻¹ (T_n from 14 to 368 days), while sediments from a third marsh in freshwater (mile point 76) had high rates (66 nmol cm⁻³ day⁻¹; T_n 40 days). For the two upstream marsh stations which rarely experienced salt intrusion, there was a substantial decrease in mineralization of naphthalene and anthracene with increasing salinity.Consistently high rates of naphthalene mineralization (780 to 1600 nmol cm⁻³ day⁻¹; T_n 5 to 6 days) were observed in petroleum contaminated sediments from Port Jefferson Harbor (PJH) on the north shore of Long Island. PJH has a relatively constant salinity regime (about 27%) and imposed decreases in salinity effected decreases in rates of naphthalene and anthracene mineralization. Lowest rates of naphthalene mineralization (0·003 to 0·004 nmol cm⁻³ day⁻¹; T_n from 714 days to 833 days) were found in sediments from two stations in the relatively pristine Carmans River estuary on the south shore of Long Island.The ability of increases or decreases in salinity to affect the rate of model PAH mineralization appeared to be dependent on the natural variation in the salinity regime from which a sample was obtained. Data from all the environments studied indicated a strong positive correlation between PAH concentration and the rates of mineralization of naphthalene. Rates of PAH mineralization in all environments examined appear to be primarily controlled by the extent of pollutant loading and not by natural variations in the salinity regime.  相似文献   

Some kinetic characteristics of exoproteolytic activity in coastal seawater     

《Estuarine, Coastal and Shelf Science》1987,25(1):127-133

The response of the exoproteolytic activity of seawater to proteolytic inhibitors suggests that metalloproteases are the main enzymes involved. The K_m of exoproteolytic enzymes for the hydrolysis of indigenous proteins in coastal north seawater has been evaluated as 80 μg l⁻¹ and the maximum rate of proteolysis lies in the range 0·1–0·35 μgC l⁻¹-enzymatic-unit⁻¹. Enrichment experiments suggest that both species selection and metabolic regulation may play a role in the exoproteolytic activity/biomass ratio. However, in situ exoproteolytic activity/biomass ratios observed in a broad range of natural marine environments lie in a very narrow range, which is intermediate between those observed after amino acid or protein enrichment.  相似文献   

Effects of heavy metals on the development and survival of abalone Haliotis midae larvae     

《African Journal of Marine Science》2013,35(2):339-345

Despite a growing abalone Haliotis midae industry in South Africa, few studies have measured the effects of heavy metals on larval survival and growth in the face of recent increases in marine pollution. The aim of this study was to quantify the effect of copper on survival and zinc on development of H. midae larvae. Larvae 24 hours old were exposed to either copper (0–30 μg l^–1) or zinc (0–200 μg l^–1) for 48 h before mortality or larval development respectively were quantified. Copper significantly reduced survival, with an LC₅₀ of 5.58 μg l^–1 (5.07–6.15, 95% CI). Although the concentrations of zinc used in the study did not have a significant effect on mortality, there was a significant effect on the incidence of abnormal larvae with an EC₅₀ of 102.25 μg l^–1 (96.68–105.94, 95% CI). At concentrations above the EC₅₀, more than 50% of the larvae showed severe developmental abnormalities. Results suggest that copper poses the greatest risk to abalone larvae as the LC₅₀ was similar to the target concentration for this metal for South African coastal waters. By contrast, zinc is potentially less problematic, with the EC₅₀ for larval development being four times the target concentration for this metal.  相似文献   

Laboratory-scale evaluation of the potential of chemical containment for farmed abalone larval escapees     

A Roux  H Lambrechts 《African Journal of Marine Science》2016,38(2):275-278

The sensitivity of abalone Haliotis midae larvae to low levels of toxicants was used to conduct a laboratoryscale experiment to determine the possibility of using chemical containment to prevent the escape of larvae from land-based culture systems, thereby reducing the environmental impact of farming operations. The cryoprotective agent, dimethyl sulphoxide or DMSO (Me₂SO), was used as a toxicant and embryos were exposed to increasing concentrations (0–25.60 mol l^–1) of DMSO for a period of 24 hours. Hatch-out rates of the control group (0.0% DMSO) did not differ from those obtained at 0.2% (2.56 mol l^–1) and 0.4% (5.12 mol l^–1) DMSO. An exposure level at and above 0.6% DMSO resulted in a significant decrease in the number of normal larvae. At an exposure concentration of 0.6% (7.68 mol l^–1) DMSO, 65% (SE 3.0) of the fertilised eggs hatched, compared to only 10% (SE 2.0) at a concentration of 1.0% (12.80 mol l^–1) DMSO. This study indicates the potential for use of DMSO as a form of chemical containment of abalone larvae, even at very low doses. It presents South African abalone farms with a chemical containment method that could potentially be used to prevent the unintentional escape of H. midae larvae from land-based operations.  相似文献   

Impact of macroalgal dredging on dystrophic crises and phototrophic bacterial blooms (red waters) in a brackish coastal lagoon     

《Oceanologica Acta》1998,21(4):551-561

The Prévost lagoon (Mediterranean coast, France), was subject to annual dystrophic crises caused by the biodegradation of opportunistic macroalgae (Ulva lactuca) in the past. These crises result in anoxic waters with subsequent blooms of Purple Sulphur Bacteria (red waters) which, by oxidizing sulphide, contribute to the reestablishment of oxic conditions in the water column. Mechanical dredging of the macroalgal biomass has been carried out in the lagoon since 1991 with the aim of preventing the ecological and economic disturbances caused by such crises. Dredging began just before the phototrophic bloom when the water was already hypoxic (O₂ = 0.7 mg·L⁻¹) and contained sulphilde (H₂S = 7.3 mg·L⁻¹) and purple patches of phototrophic bacteria (Thiocapsa sp.) that were beginning to develop on decaying macroalgae at the sediment surface. The dredging prevented red water formation and drastically modified both phototrophic community structure and activity and biogeochemical sulphur cycling. The dredging permitted the reestablishment of oxic conditions for a short period only (1–13 August). Resuspension of the superficial sediment layers disturbed the phototrophic bacterial community, whose numbers decreased by one order of magnitude (from 2 × 10⁶ to 3.9 × 10⁵ CFU.mL⁻¹). The phototrophic community was no longer effective in reoxidizing the reduced sulphur compounds remaining in the sediments, as shown by a drastic sulphate depletion in the superficial sediment layers. Moreover, the increase in the specific bacteriochlorophyll a concentration of the phototrophic purple bacteria and the rapid development of Green Sulphur Bacteria (Prosthecochloris-like microorganisms) indicated that the phototrophic community was growing under severe light-limiting conditions due to the resuspension of sediment particles in the water. These conditions did not allow the phototrophic bacterial community to efficiently reoxidize the reduced sulphur compounds originating from the sediments. In consequence, hypoxic conditions (O₂ = 4.7 to 4.8 mg·L⁻¹) and low sulphide concentrations (H₂S = 0.4 to 0.7 mg·L⁻¹) were detected in the water column until September. The ecological balance in the lagoon was reestablished only in October, whereas, in previous years it had been restored in August.  相似文献   

Chlorophyll distribution in continental shelf sediments off West Palm Beach,Florida and west end,Bahamas     

John J. Heffernan  Robert A. Gibson 《Estuarine, Coastal and Shelf Science》1983,17(1):107-110

Measurements were made of chlorophyll-a and phaeophytin-a in calcareous sediments along transects off the east coast of Florida (75–190 m) and the west coast of Grand Bahama Island (170–300 m). Solvent partitioning showed that chlorophyll-a concentrations never exceeded 0·1 mg m^?2 at either location, most as degradation products. Total pigment concentrations (chlorophyll and phaeopigments) ranged from 0·18–1·83 mg m^?2 in sediments off Grand Bahama Island and 2·50 to 20·65 mg m^?2 off West Palm Beach. Pigments, expressed per gram dry weight of sediments, increased with depth across the Florida Continental Shelf. This is probably due to differences in sediment character between near-shore and off-shore sediments.  相似文献   

Accumulation of Zn,Cu and Cd by crabs and barnacles     

P.S. Rainbow 《Estuarine, Coastal and Shelf Science》1985,21(5):669-686

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   

Chlorinated hydrocarbons in the seawater and surface sediments of Blanca Bay,Argentina     

JoséLuis Sericano  Adan E. Pucci 《Estuarine, Coastal and Shelf Science》1984,19(1):27-51

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   

Trace metals in the Göta river estuary     

Lars-Göran Danielsson  Bertil Magnusson  Stig Westerlund  Kerong Zhang 《Estuarine, Coastal and Shelf Science》1983,17(1):73-85

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   

Productivity of dinoflagellate blooms on the west coast of South Africa,as measured by natural fluorescence     

《African Journal of Marine Science》2013,35(1):273-284

The biomass and productivity of phytoplankton populations inshore on the west coast of South Africa were investigated towards the end of the upwelling season, a period when high-biomass dinoflagellate blooms are common. Productivity was estimated from natural fluorescence measurements (P_NF ), using photosynthesis (P) v. irradiance (E) relationships (P_E ) and by means of the in situ ¹⁴C-method (P_C ) A linear regression of P_NF productivity against P_C and P_E productivities yielded a slope of 0.911 and an r ₂ of 0.83 (n = 41). Physical and biological variability was high inshore, reflecting alternating periods of upwelling and quiescence. Mean chlorophyll inshore (within a 12 m water column) ranged from 0.7 to 57.8 (mean = 8.9) mg·m^&minus3, mean P_NF productivity ranged from 8.4 to 51.0 (mean = 24.6) mgC·m^?3·h^?1 and daily integral P_NF productivity from 0.8 to 4.8 (mean = 2.3) gC·m^?2·day^?l. Transects sampled during active and relaxation phases of upwelling had different chlorophyll distributions. High chlorophyll concentrations (sometimes >50 mg·m^?3) were associated with surface blooms within the region of the upwelling front. Estimates of daily water-column P_NF productivity within these frontal blooms ranged from 4.0 to 5.6 gC·m^?2·day^?1. With relaxation of wind stress, blooms dominated by dinoflagellates flooded shorewards and often formed red tides. Chlorophyll concentrations of > 175 mg·m^?3 and productivity rates > 500 mgC·m^?3·h^?1 and 12 gC·m^?2·day^?1 were measured during a particularly intense red tide. Offshore, the water column was highly stratified with a well-defined subsurface chlorophyll maximum layer within the pycnocline region. Estimates of daily water-column P_NF productivity ranged from 2.4 to 4.0 gC·m^?2·day^?1 offshore. The high productivity of shelf waters on the West Coast in late summer can be ascribed largely to dinoflagellate populations and their success in both upwelling systems and stratified conditions.  相似文献   

Macrobenthos relative to the oxygen minimum zone on the East Indian margin,Bay of Bengal          下载免费PDF全文

Akkur V. Raman  Rayaroth Damodaran  Lisa A. Levin  Thiruchitrambalam Ganesh  Yannamani K. V. Rao  Sateesh Nanduri  Rakhesh Madhusoodhanan 《Marine Ecology》2015,36(3):679-700

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   

Chemical determination of particulate nitrogen in San Francisco Bay. Nitrogen: chlorophyll a ratios in plankton     

S.W. Hager  D.D. Harmon  A.E. Alpine 《Estuarine, Coastal and Shelf Science》1984,19(2):193-204

Particulate nitrogen (PN) and chlorophyll a (Chla) were measured in the northern reach of San Francisco Bay throughout 1980. The PN values were calculated as the differences between unfiltered and filtered (0·4 μm) samples analyzed using the UV-catalyzed peroxide digestion method. The Chla values were measured spectrophotometrically, with corrections made for phaeopigments. The plot of all $\text{PN}\text{Chl}\text{a}$ data was found to be non-linear, and the concentration of suspended particulate matter (SPM) was found to be the best selector for linear subsets of the data. The best-fit slopes of $\text{PN}\text{Chl}\text{a}$ plots, as determined by linear regression (model II), were interpreted to be the N: Chla ratios of phytoplankton. The Y-intercepts of the regression lines were considered to represent easily-oxidizable detrital nitrogen (EDN). In clear water ( < 10 mg l^?1 SPM), the N: Chla ratio was 1·07 μg-at N per μg Chla. It decreased to 0·60 in the 10–18 mg l^?1 range and averaged 0·31 in the remaining four ranges (18–35, 35–65, 65–155, and 155–470 mg l^?1). The EDN values were less than 1 μg-at N l^?1 in the clear water and increased monotonically to almost 12 μg-at N l^?1 in the highest SPM range. The N: Chla ratios for the four highest SPM ranges agree well with data for phytoplankton in light-limited cultures. In these ranges, phytoplankton-N averaged only 20% of the PN, while EDN averaged 39% and refractory-N 41%.  相似文献