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1.
Abstract

The influence of temperature on the acute toxicity of a technical formulation (86%) and pure formulation (99%) of pentachlorophenol (PCP) to less than 24‐h‐old Simocephalus vetulus neonates was determined with 48‐h static toxicity tests. The technical grade PCP was significantly more toxic to S. vetulus than the pure PCP (P < 0.05). Sensitivity of S. vetulus to technical PCP also significantly increased with temperature (P < 0.05), but a significant temperature effect was not found with the pure PCP. The mean 48‐h LC50 values for neonates exposed to technical PCP were 140 and 199 μg l?1 at 22°C and 16°C, respectively, and for those exposed to pure PCP were 262 and 304 μg l?1, respectively.  相似文献   

2.
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   

3.
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   

4.
Abstract

Chemical parameters (pH, Eh, carbon, Kjeldahl nitrogen, total phosphorus, 0.5M H2SO4‐extractable phosphorus, organic phosphorus, and water‐soluble phosphorus) were measured in the surface layers of sediments collected from various depths in Lakes Rotowhero, Okaro, Ngapouri, Rotokakahi, Okareka, Tikitapu, Okataina, and. Rotoma during October 1972. The sediments of the productive geothermal lake, Rotowhero, were markedly different from those of the cold‐water lakes: they had relatively low pH values, high carbon (mean 8.5%) and organic phosphorus (mean 4160 μg.g?1) concentrations, and very high total phosphorus concentrations (mean 4770 μg.g?1), probably as a result of enrichment by hot springs.

The mean concentrations in the sediments of the cold‐water lakes were carbon 3.2–7.9%, Kjeldahl nitrogen 3380–8310 μg.g?1 and phosphorus 690–1780 μg.g?1. These concentrations are within the ranges for New Zealand terrestrial topsoils, but the lake sediments appear enriched in phosphorus relative to local topsoils. Total carbon, nitrogen, and phosphorus concentrations of sediments tended to be highest in the eutrophic lakes (Okaro, Ngapouri) although the deep oligotrophic lakes (Okataina, Rotoma) had relatively high total phosphorus concentrations (means 1400, 1510 μg.g?1). Overall, the carbon, nitrogen, and phosphorus concentrations of the sediments showed little relationship to the trophic state of the lake.

Organic phosphorus concentrations of the surface layers of sediments were similar in all the cold‐water lakes (mean 319 μg.g?1). The proportion of the total phosphorus apparently ‘fixed’ in mineral material was minimal (0–1%) in sediments from the eutrophic and mesotrophic lakes, but in the oligotrophic lakes was similar to that in New Zealand topsoils (9–14%). Reducing conditions may cause solution of a high proportion of the ‘fixed’ phosphorus in the eutrophic lakes.

The water‐soluble phosphorus concentrations in the sediments of the five shallow cold‐water lakes (Okaro, Ngapouri, Rotokakahi, Okareka, Tikitapu) correlated positively with trophic state and with concentrations of dissolved phosphorus in the lake waters.

Carbon, nitrogen, and phosphorus concentrations in the sediments tended to vary with overlying water depth. This should be considered when comparisons are made between lakes.  相似文献   

5.
Concentrations of mercury were determined for the waters, suspended matter and sediments of the Tagus and of major French estuaries.The Tagus estuary is one of the most contaminated by mercury derived from the outfalls of a chloralkali plant and from other industrial sources. In deposited sediments the median level, 1·0 μg Hg g?1, is twenty times higher than the natural background and Hg contents depend on the sediment grain-size, age and the distance from waste-outfalls. Suspended matter is more regularly and highly contaminated (median value: 4·5 μg Hg g?1). In the French estuaries Hg levels in the suspended material decrease with salinity due to dilution and/or remobilization processes. In June 1982, in the Loire estuary, high values of Hg are observed in the middle estuary and attributed to urban and industrial sources.In the Tagus estuary, the general distribution of total dissolved Hg confirms the contamination: it increases seaward from 10 ng 1?1 in the river to 80 ng 1?1 in the estuary outlet. The dissolved Hg is almost totally organic in the river, inorganic in the middle estuary due to inorganic Hg effluents and again organic in the lower estuary. This variation is related to the dissolved organic carbon values. The dissolved Hg levels in the Loire Estuary (5–300 ng 1?1) are much higher than in the Gironde estuary (3–6 ng 1?1) and of the same order as those observed in the Tagus estuary.  相似文献   

6.
Cd, Cu, Fe, Ni, Pb and Zn were determined in 123 samples from the Baltic Sea proper. The trace metals were extracted directly on board the vessel, using a dithiocarbamate-Freon procedure. Final analyses of the extracts are performed onshore by atomic absorption spectrometry.Similar trace-metal concentrations are found in different areas of the Baltic proper. Most values fall in the following ranges: Cd, 30–60 ng 1?1; Cu, 0.6–1.0 μg 1?1; Fe, 0.3–0.9 μg 1?1; Ni, 0.6–0.9 μg 1?1; Pb, 0.05–0.2 μg 1?1; and Zn, 1.5–3.5 μg 1?1. The metal-concentrations are generally independent of depth. However, copper exhibits a small but significent decrease in concentration below 80 m.Filtration did not affect trace-metal concentrations, with the exception of iron in waters from lower layers. Similarly, storage under acid conditions was shown to affect only the concentration of iron. An electro-chemical technique was also used to determine Cu in some samples.  相似文献   

7.
The effects of cresols on the photosynthesis and growth of natural marine phytoplankton assemblages from the Scripps Pier at La Jolla, California, USA were measured. In two experiments, in which dinoflagellates were the dominant algae, photosynthesis (measured by 14C uptake) was inhibited at concentrations > 100 μg litre?1 and the concentration giving half-maximal photosynthesis was 10,000 μg litre?1. In a third experiment, in which diatoms were dominant, photosynthesis was not inhibited until levels > 10,000 μg litre?1 were reached and the half-maximal concentration was 20,000 μg litre?1. These experiments suggested that dinoflagellates were more sensitive to cresols than diatoms. However, the reverse was true in an experiment using cultures. In a long-term growth experiment (natural assemblages from the Scripps Pier), only a level of 88,000 μg litre?1 completely inhibited growth. There was a two-day lag in growth at 8500 μg litre?1, but the algae recovered and grew as well as the controls which contained no cresols. This experiment was started with a mixed diatom-dinoflagellate-microflagellate population but only the diatoms grew. High concentrations of cresols (> 900 μg litre?1) resulted in a decrease in the diatom Skeletonema costatum, compared with the controls. Otherwise there was no selection for resistant species. In these experiments, cresols were measured by extraction with methylene chloride from seawater followed by measurement by UV absorption. In all experiments cresol levels decreased with time. This was attributed to uptake by phytoplankton and bacterial degradation.  相似文献   

8.
The different mineral phases of the ferromanganese (Fe–Mn) crusts stem from the interaction of biotic and abiotic components. It is therefore vital to study the activity of these components to decipher their contribution to the enrichment/depletion of metals in the crust. Thus, the present study examined sorption and release of Co and Ni by Fe-Mn crusts with associated microbial communities in the presence and absence of the metabolic poison sodium azide (15?mM). The study was conducted in the presence (G+) and absence (G?) of added glucose (0.1%) at temperatures of 4?±?1°C and 28?±?2°C. Results showed that the microbial community had maximal sorption of Co of 66.12?µg?g?1 at 4?±?1°C in the absence of added glucose and 479.75?µg?g?1 at 28?±?2°C in the presence of added glucose. Maximum sorption of Ni in the absence of added glucose was 1.89?µg?g?1 at 4?±?1°C and release of Ni was 51.28?µg?g?1 in the presence of added glucose. Under abiotic conditions with 15?mM sodium azide as a metabolic inhibitor, significant amounts of Co and Ni were released in the G+ medium. Total cell counts on the Fe-Mn crust in the presence of added glucose increased by an order of magnitude from 106 to 107 cells g?1 and in the absence of added glucose remained within the order of 106 cells?g?1 irrespective of temperature of incubation. Microscopic observation of the samples from biotic incubations showed numerous bacterial cells, exopolysaccharides, and structures resembling secondary minerals formed by bacteria. The results indicate that bacteria promote the enrichment of Co and Ni on the hydrogenetic Fe-Mn crusts by sorption processes and release of Ni by reductive dissolution of the oxides. The higher enrichment of Co than Ni is attributed to the way in which microbes interact with the metals.  相似文献   

9.
In the Russian sector of the Gdansk Basin (Baltic Sea), high organic matter influx fuels microbial processes resulting in the formation of reduced sediments with elevated methane concentrations. Investigated areas of geoacoustic anomalies (～245 km2) were found to contain three distinct geomorphologic structures (pockmarks), with a total area of ～1 km2. Methane anomalies recorded in the water above one of these pockmarks were traced as high as 10 m above the bottom. In pockmark sediments, sulfate reduction and anaerobic oxidation of methane (AOM) occurred at high rates of 33 and 50 µmol dm?3 day?1, respectively. Integrated over 0–180 cm sediment depths, AOM exceeded methanogenesis almost tenfold. High AOM rates resulted from methane influx from deeper sediment layers. The δ13C signature of methane carbon (?78.1 to ?71.1‰) indicates the biogenic origin of pockmark methane. In pockmark sediments, up to 70% of reduced sulfur compounds was possibly produced via AOM.  相似文献   

10.
Pacific oyster, Crassostrea gigas Thunberg, embryos were exposed to copper and silver salts, alone and in combination, through the completion of embryogenesis and metal effects upon normal embryonic development were monitored. Copper concentrations throughout the test period ranged from 0·0 to 12·0 μg litre?1 while silver concentrations were between 0·0 and 18·0 μg litre?1.Administered individually, silver and copper yielded decreasing per cent normal embryonic development with increasing metal concentration. However, both metals exhibited ‘plateaus’ wherein per cent normal embryonic development did not decrease with increasing metal concentration until a particular concentration was attained. A rapid decrease in per cent normal embryonic development occurred with increasing metal concentrations greater than 6·0 μg litre?1 copper and 11·0 μg litre?1 silver.The dose-response patterns of copper and silver appear to be similar with copper exhibiting somewhat greater toxicity. At a copper concentration of 10 μg litre?1 only 50% of the embryos could be considered normally developed, whereas silver concentrations between 16·0 and 18·0 μg litre?1 yielded 50% normal embryonic development.Response surface methodology indicated that copper and silver interacted additively, with embryonic development affected to a much greater degree by copper than by silver. Optimum development of Crassostrea gigas embryos was greatly influenced by copper concentrations and occurred at all silver concentrations wherein the corresponding copper concentrations were 6·0 μg litre?1 or less. Above 6·0 μg litre?1 copper, per cent normal embryonic development was significantly reduced, even at the lowest tested silver concentrations.Abnormal embryos exhibited retarded shell growth, reduced size and extremely erratic swimming behaviour. These sublethal effects probably have a biochemical origin and would limit the organism's capacity to feed properly, escape predation and develop normally, thereby reducing the chances of successful metamorphosis and recruitment into the adult population.  相似文献   

11.
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   

12.
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   

13.
A mathematical model that computes the accumulation of Kepone in the striped bass food chain of the James River estuary was developed. The purpose of the model was to help understand the relationship of Kepone levels in important fish species to sediment and water column Kepone concentrations and then to address the question of why these levels still exceed Food and Drug Administration limits eight years after discharge ceased. The model considers exposure through diet and respiration at rates based on species bioenergetics. It was successfully calibrated to the Kepone concentrations observed in the period 1976 through 1982 in striped bass, white perch, and Atlantic croaker. The model indicates that for the upper levels of the food chain, diet is the major route of contamination, accounting for 87–88% of the observed concentration in croaker and white perch and 91% of the observed concentration in striped bass. The two Kepone sources; sediment and water column, contribute approximately equally to the croaker and white perch. The water column is more significant for striped bass, being the original source for approximately 60% of the observed body burdens. It was estimated that a criterion requiring Kepone concentrations in fish to be at or below 0·3 μg g?1 would require dissolved water column and sediment Kepone concentrations to be reduced to somewhere between 3 and 9 ng l?1 and 13–39 ng g?1, respectively, depending on the species. Striped bass require the greatest reductions in dissolved water column and sediment Kepone concentrations to somewhere between 3 and 5 ng l?1 and 13 and 24 ng g?1, respectively.  相似文献   

14.
Net aerial production of Spartina maritima (Curtis) Fernald, in a warm temperature estuary in Algoa Bay, South Africa, occurring possibly as an exotic, was estimated as 523–680 g dry weight m?2 year?1. The method of production measurement designed here used community structure data and accounted for the species' extremely slow shoot production (3.1–6.7 dry g m?2 year?1) and continuous leaf turnover (516–676 dry g m?2 year?1). Standard methods of production measurement for other Spartina species failed by not accounting for the non-seasonal growth of S. maritima. N, C, organic and energy content of live and dead shoots remained constant through the seasons. The P : B ratio is 1.1, which is lower than for other Spartina species, but agrees with the low vigour shown by negligible regrowth a year after clipping. Decomposition rates were 90 mg g?1 month?1 in winter and 305 mg g?1 month?1 in summer. Monthly decomposition values showed significant correlation with air temperature (r = 0.86; P < 0.01), and water temperature (r = 0.80; P < 0.01), suggesting that monthly litterbag losses are a valid means of determining decomposition rate.  相似文献   

15.
This study compared the very different responses of the polychaete Neanthes arenaceodentata to chronic exposure of hexavalent (Cr VI) and trivalent (Cr III) chromium. The polychaetes were exposed to sublethal concentrations of Cr VI and Cr III for periods of 440 days (three generations) and 293 days (two generations), respectively. In the Cr VI test, polychaete reproduction ceased at 100 μg litre?1, and the number of young produced was reduced at the 12·5 to 50 μg litre?1 levels and above. However, polychaetes that lived in Cr III during the test showed no adverse effects in 50400 μg litre?1.  相似文献   

16.
In this study, we examined the impact of temperature on the carbon and nitrogen trophic transfers from a macroalga to a macro‐grazer by the use of dual 13C‐ and 15N‐labeling. Using an experimental approach in mesocosms, individuals of the urchin Psammechinus miliaris were maintained for 1 month at 17°C (mean summer temperature in the Bay of Brest) and at 20°C (maximum summer temperature) and fed with 13C‐ and 15N‐labeled Solieria chordalis. The results showed that the urchins’ 13C uptake was 0.30 µg13C g dry weight (DW)?1 at 17°C and 0.14 µg13C g DW?1 at 20°C at the end of the experiment. The lower uptake at the higher temperature may be attributed to a decrease in metabolic activity at 20°C, involving lower feeding and/or respiration rates. Conversely, no significant effect of temperature was detected on 15N uptake. At the end of the experiment, the urchins’ 15N uptake was 0.04 µg15N g DW?1 at 17°C and 0.03 µg15N g DW?1 at 20°C. This suggests that temperature may affect carbon and nitrogen trophic fluxes differently. The use of dual isotope labeling offers interesting prospects and needs to be further extended in order to better understand trophic interactions in marine communities and the consequences of current environmental changes, such as global warming.  相似文献   

17.
Phytoplankton chlorophyll concentrations in the Delaware estuary range over two orders of magnitude and display several maxima over the seasonal cycle. These maxima were found to be regulated both spatially and temporally by light availability. Both the spring chlorophyll maximum, which reaches 50–60 μg chlorophyll l?1 during a Skeletonema costatum dominated bloom, and transient fall blooms (15–20 μg l?1) are focused in mid-estuary. These blooms are regulated spatially by settling out of suspended sediment below the turbidity maximum and both spatially and temporally by physical factors (e.g. river flow) that cause vertical stratification in mid-estuary. In freshwater regions, chlorophyll concentrations display seasonal periodicity correlated with solar irradiance; summer chlorophyll concentrations average 30 μg l?1. These freshwater and mid-estuarine biomass maxima may be correctly predicted using a steady-state light-limitation model. In contrast, summer chlorophyll concentrations in the lower estuary remain below 10 μg l?1 and are not correctly modeled, despite minimum turbidity, and non-nutrient limiting conditions. These chlorophyll concentrations appear to be regulated by a combination of light availability and grazing.Although extremely high anthropogenic nutrient inputs in the freshwater region of the Delaware River provide non-limiting nutrient concentrations throughout the estuary, regulation of phytoplankton growth by light-limitation restricts chlorophyll concentrations below the nuisance levels found in many eutrophic systems.  相似文献   

18.
The loss of added 15N-labelled NH4+ from bottom sediment was studied in situ in a shallow saline Louisiana Gulf Coast lake. 15N-labelled NH4+ was uniformly mixed with sediment at the level of 35 μg N g?1 dry sediment for 24 h before being weighed into polyethylene containers. The 15N-enriched sediment was incubated on the lake bottom for periods up to 337 days. At intervals, triplicate samples were taken and analyzed for inorganic NH4+, organic N, and denitrification rates. Concentrations of NH4+ in the 15NH4+ enriched sediment samples were at levels similar to those measured in vertical intact cores removed from the lake at each sampling date. The initial and final isotopic compositions of NH4+ in the incubated sediments were 44.26 and 0.521 atom % 15N excess, respectively. 15N enrichment in the organic N fraction increased rapidly during the first 15 days of incubation and then increased slowly from 15 to 123 days. Denitrification, estimated by the acetylene blockage technique, ranged from 0.994 to 0.079 ng N g?1 dry sediment per hour. The mean denitrification rate for the 337-day period was 0.28 ng N g?1 h?1. There was no statistical difference in the recovery of 15N between 15 and 337 days of incubation. When the added 15N became incorporated into the organic N pool, little or no further 15N was lost.  相似文献   

19.
A limited survey was undertaken to determine the concentrations of copper, lead, and chromium in sediments of the upper Manukau Harbour, New Zealand. The concentrations of copper and chromium (33–70 and 70–107 μg g‐1 respectively) were of the same order of magnitude as those reported for other New Zealand harbours. However, lead concentrations (98–247 μg g‐1) were higher than those found for the other harbours. This may be a consequence of higher traffic densities in the surrounding area.  相似文献   

20.
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   

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