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1.
A microcosm experiment was designed to evaluate the effects of the simulated deposition of uncontaminated dredged material
on nematode assemblages from estuarine intertidal mud. The main objective was to assess the ability of nematodes to migrate
vertically into native muddy and non-native sandy sediment deposited in different amounts and frequencies. Results from univariate
and graphical methods of data-evaluation revealed that nematodes were capable of migrating over a wide depth range from the
bottom mud layer into the top layer of deposited sand and mud. A diverse mud assemblage of nematodes was able to survive in
non-native fine sand for the experimental period of 2 mo. Multivariate analyses showed that the amount of deposit and the
frequency of deposition were interactive factors. A high amount of sediment deposited once at the beginning of the experiment
caused more severe changes in assemblage structure than the same amount deposited in more frequent but smaller doses. The
response of most species to the experimental treatments appeared to be an integrated response to the enhancing effect of food
input accompanying the deposit and the negative effect of burial. Upward migration of nematodes is a process which has often
been underestimated in its importance for recolonisation of areas where uncontaminated dredged material is deposited. Active
migration of nematodes can significantly affect the recovery of a dredgings disposal site.
Received: 29 July 1999 / Accepted: 17 January 2000 相似文献
2.
Certain criteria must be satisfied before a licence for the deposition of dredged material at sea in UK waters is issued.
These relate to the chemical quality of the material, the quantity to be disposed of, its nature and origin, and its predicted
impacts at the disposal site. Although chemical analyses of dredgings provide an indication of the relative degrees of contamination,
they do not provide a measure of any resultant biological effects. A laboratory experiment was therefore designed to investigate
the effects of the degree of contamination and the role of burial associated with the deposition of dredged material on the
meiofauna. Estuarine nematode assemblages were exposed to the simulated deposition of uncontaminated, oxic intertidal mud
and anoxic sediments from the Mersey and the Tees estuaries, both of which were contaminated with heavy metals. The sediments,
which differed little in terms of grain size, were deposited in two different frequencies. Nematodes showed a clear species-specific
response to the experimental treatments, depending on the frequency of deposition and the chemical quality of the deposited
material (e.g. metal and oxygen concentrations). The response of nematode assemblages was mainly determined by the deposition
frequency rather than the type of sediment or the degree of contamination. The deposition of sediment in one large dose at
the beginning of the experiment caused more severe changes in assemblage structure than the same quantity deposited in several
smaller doses. Although lower than in uncontaminated mud, relatively high migration and survival rates in the contaminated
high-frequency treatments were observed. This may have been due to reduced bioavailability of metals and the tolerance of
estuarine nematodes to both metal contamination and the deposition of small sediment volumes at regular intervals. The observed
trends demonstrate the potential of small-scale laboratory experiments for testing the quality of contaminated dredged material
at the licensing stage, i.e. prior to the issue of a disposal licence.
Received: 11 February 2000 / Accepted: 26 June 2000 相似文献
3.
A study on the levels of N‐methylcarbamate pesticides and some degradation products in waters of the river Huelva was carried out. This river constitutes the main water supply of the city of Seville at the south west of Spain with a population of almost one million inhabitants. N‐methylcarbamates were extracted from the water by using C‐18 solid phase cartridges. High performance liquid chromatography with UV detection was used to carry out the determinations. Residues of carbaryl, methiocarb sulphoxide and α‐naphthol were found in some of the analysed water samples. 相似文献
4.
Ecosystem-focused models have, for the first time, become available for the combined demersal and pelagic components of a large tropical lake ecosystem, Lake Malawi. These provide the opportunity to explore continuing controversies over the production efficiencies and ecological functioning of large tropical lakes. In Lake Malawi these models can provide important insight to the effect of fishing on fish composition, and the potential competition that the lakefly Chaoborus edulis may have with fisheries production. A mass-balanced trophic model developed for the demersal fish community of the southern and western areas of Lake Malawi was integrated with an existing trophic model developed for the open-water pelagic. Input parameters for the demersal model were obtained from a survey of fish distributions, fish food consumption studies, and from additional published quantitative and qualitative information on the various biotic components of the community. The model was constructed using the Ecopath approach and software. The graphically presented demersal food web spanned four trophic levels and was based primarily on consumption of detritus, zooplankton and sedimented diatoms. Zooplankton was imported into the system at trophic levels three and four through fish predation on carnivorous and herbivorous copepods and Chaoborus larvae. It is proposed that the primary consumption of copepods was by fish migrating into the pelagic zone. Chaoborus larvae in the demersal were probably consumed near the lakebed as they conducted a daily migration from the pelagic to seek refuge in the sediments. This evidence for strong benthic-pelagic coupling provided the opportunity for linking the demersal model to the existing model for the pelagic community so producing the first model for the complete ecosystem. Energy fluxes through the resulting combined model demonstrated that the primary import of biomass to the demersal system was detritus of pelagic origin (72.1%) and pelagic zooplankton (10.6%). Only 15.8% of the biomass consumed within the demersal system was of demersal origin. Lakefly production is efficiently utilised by the lake fish community, and any attempt to improve fishery production through introduction of a non-native plantivorous fish species would have a negative impact on the stability and productivity of the lake ecosystem. 相似文献
5.
《生态环境》2003,(4)
No.1 Research Papers Effect of digestion on measurement of total mercury in topsoil …………………………………………………………… DING Zhen-hu, WANG Wen-hua(1) The characteristics of adsorption and desorption of humic acids on copper…………………………………………………… LI Guang-ling, WEI Shi-qiang(4) Influence of electrolyte on adsorption of copper in soils……………………………………………………… LI Ying, LI Hong-jun, ZHANG Gui-yin, et al.(8) Comparative studies on availabl… 相似文献
6.
Laboratory studies were conducted to determine the adsorption/desorption equilibrium of carbofuran between four divergently textured soils and distilled water and an aqueous solution of 0.01?mol?L?1 β-cyclodextrin using a batch equilibrium technique. The determined adsorption isotherms for silt loam soils were of L-shaped, for sandy loam soil S-shaped, in agreement with a Freundlich isotherm. In the presence of β-cyclodextrin, the adsorption of carbofuran to the four soils was lower than with distilled water. Positive hysteresis was observed in all soils with distilled water, negative hysteresis when using a solution of β-cyclodextrin as desorbent. The results indicate the potential use of β-cyclodextrin for remediation of pesticide-contaminated soils. 相似文献
7.
Differential Pulse Anodic Stripping Voltammetry (DPASV) was employed to measure Apparent Copper Complexing Capacity (Lt) and Stability Constants (Ks) of related cupric complexes of cell exudates of the phytoplanktonic alga Dunaliella salina. Three natural seawater samples collected 0.1, 2, 5 miles off the Tyrrhenian coast were used as culture medium. The measurements were carried out 1h and 7 days after the inoculum. Furthermore, on one culture the medium was passed through C18‐SEP‐PAK cartridges in order to separate the cell exudates. The results show that Dunaliella salina influences the value of Lt but does not affect the value of Ks . The C18SEP‐PAK retain only 50% of the ligands produced by the cells and capable of complexing copper. 相似文献
8.
In plant configuration of landscaping, herbaceous plant is often inter-planted with ornamental tree species. But unreasonable plant collocation may reduce the effectiveness of afforestation for the inhibition effect of tree on the growth of understory, and further more affect the greening effect. Camphor (Cinnamomum camphora) is widely planted in landscaping accompanying herbaceous plants including morning glory (Pharbitis nil). But camphor was reported to have allelopathic effect on its adjacent plant, therefore correct selection and collocation of plants has important significance to obtain good greening effect. This research aimed to study by a pot experiment the effects of decomposing leaf litter of Cinnamomum camphora on the growth, phenological traits of Pharbitis nil, as well as modification of these effects by nitrogen application. Three application rates of C. camphora leaf litter including 25, 50 and 100 g/pot (denoted by L25, L50 and L100, respectively) and a control (CK) were implemented. Nitrogen application began on the 34th d of decomposition, with 0.39 g urea being divided into three equal portions and added continuously to each pot. The results showed that (1) The height, basal diameter, leaf area and biomass production of Pharbitis nil were all inhibited sharply by exposure to the leaf litter, being decreased by 32.85%-83.78%, 5.23%-23.00%, 30.31%-58.47%, and 40.34%-84.54%, respectively, with the inhibition effect increasing both in intensity and stability with the increase of leaf litter. Such inhibition effect was obviously alleviated by exogenous nitrogen application. (2) The flowering dynamics of Pharbitis nil was greatly impacted by the leaf litter, with the flower initiation 2.5-10.0 d later and the flowering duration 6.3-11.4 d longer compared to the control. Although the leaf litter-treated plants exhibited more (0.5-3.3) flowers than the control, their quality decreased, and the hundred-grain weight of the seed decreased with the increase of leaf litter. However, the differences among treatments in the reproductive parameters mentioned above reduced after nitrogen fertilization. The results indicated that leaf litter of C. Camphora has a great allelopathic effect on morphological and reproductive growth of Pharbitis nil, which may be attributed to the release of phototoxic substances during the decomposition process. 相似文献
9.
J. W. Farrington B. W. Tripp J. M. Teal G. Mille K. Tjessem A. C. Davis 《毒物与环境化学》2013,95(3-4):331-346
Investigations into the fate of petroleum compounds in the marine environment were carried out using experimental microcosms of two sizes and designs. Aromatic hydrocarbons or No. 2 fuel oil were spiked to the water of a 13 m3 continuous flow system and to a 2281 recycled flow system. The transport and alteration of this oil was traced in the sediment and benthic organisms (Glycera americana, Crepidula sp., and Nephtys incisa) of these microcosms. Measurable contamination was found in both sample types. The aromatic hydrocarbon distribution, including relative isomeric distribution (e.g., C2‐phenanthrenes) was found to be different in sediment and in organisms from that which was originally introduced to the experimental microcosm. Differences in isomer distribution between Glycera and Crepidula were also detected. Based on the experimental data: molecular weight and specific isomeric form, biochemical processes, solubility, and particle adsorption/desorption influence the fate of petroleum compounds in benthic ecosystems. 相似文献
10.
Predictions from a k-ε model are compared with recently acquired experimental data from inclined negatively buoyant discharges. The k-ε model is part of a standard computational fluid dynamics package (CFX). Two approaches are taken when implementing the model. One involves using an essentially standard form of the model to predict flow behaviour. The other approach involves calibrating the model, through adjustment of the turbulent Schmidt number in the tracer transport equation, to achieve reasonable predictions for positively buoyant vertical discharges and then applying it to inclined negatively buoyant discharges. While the calibrated approach improves the predictions of some bulk parameters (notably the tracer spread and dilution) when compared to predictions from the standard model, the overall effect on the quality of the predictions is small. Comparisons with experimental data indicate that predictions from both the standard and calibrated simulations compare favourably with trajectory data, but integrated dilution predictions at the centreline maximum height are conservative (mean-integrated concentrations are over-predicted). The standard and calibrated k-ε predictions confirm the importance of buoyant instabilities on the lower (inner) side of the flow, the effects of which are clearly evident in the mean concentration profiles. However, these simulations have a tendency to overestimate the influence of stabilizing density gradients on the upper (outer) side of the flow and are unable to effectively predict the cross-sectional distribution of a tracer. In contrast to a previous study, the above comparisons indicate that predictions of bulk parameters from such models can be poor and indeed are no better than those obtained from relatively simple analytical solutions. 相似文献
11.
Biosynthetic origin of carbon-based secondary compounds: cause of variable responses of woody plants to fertilization? 总被引:10,自引:0,他引:10
Erkki Haukioja Vladimir Ossipov Julia Koricheva Tuija Honkanen Stig Larsson Kyösti Lempa 《Chemoecology》1998,8(3):133-139
Summary. We propose that variation in the responses of carbon-based secondary compounds to fertilization in woody plants has a biosynthetic
cause. The synthesis of phenylpropanoids and derived compounds (e.g., condensed tannins) competes directly with the synthesis of proteins, and therefore with plant growth, because of a common
precursor, phenylalanine. In contrast, the biosynthesis of terpenoids and of hydrolyzable tannins proceeds presumably without
direct competition with protein synthesis. Therefore, accelerated plant growth induced by fertilization may cause a reduction
in concentrations of phenylpropanoids but may affect less or not at all the levels of other classes of secondary compounds.
A meta-analysis based on fertilization experiments with 35 woody plant species supported the predicted differences fertilizing
significantly decreased concentrations of phenylpropanoids but not of terpenoids or hydrolyzable tannins.
Received 14 May 1998; accepted 23 June 1998. 相似文献
12.
Typically, studies of the disturbance effect on metapopulation dynamics are limited to understanding the effect of habitat loss although, recently, the spatial pattern of the disturbance has been shown to influence dynamics. In this study, we used a stochastic patch-dynamic model to investigate the effects of spatial disturbance patterns on the persistence of an open woodland community of Juniperus spp. and Pinus spp. First, we estimated patch-occupancy dynamics by using the coefficients that best predicted the occupancy observed in 1998 based on occupancy data from 1957. Next, we evaluated the effects of the rate and pattern of the disturbance on the extinction probability. In modeling the disturbance, we considered (1) the degree of disturbance produced by scenarios of complete destruction or degradation (with the potential for recolonization), (2) the overall rate of disturbance, and (3) the spatial autocorrelation of habitat destruction. Twenty 40-year simulations predicted a 25% increase in the number of patches, and when 50% of the habitat was removed, the impact was more pronounced after complete destruction than it was after degradation of the area. Predictions based on scenarios of complete destruction, including random, contiguous, Brownian, and autoregressive noise, demonstrated that the impact of disturbance depends upon the spatial structure of the disturbance regimen. The autocorrelated structure of the disturbance regimen had the greatest impact on patch persistence. Patch-occupancy was higher after 20 40-year simulations when habitat loss was randomly distributed than when it followed an autocorrelated patch destruction, which was simulated using autoregressive noise to produce 50% habitat destruction. In addition, while habitat loss was negatively linearly correlated with patch persistence when habitat destruction was randomly distributed, a dramatic transition shift occurred when habitat destruction was simulated following an autoregressive spatial distribution after a certain threshold of habitat destruction (40% of the actual open woodland habitat). Our study suggests that the spatial patterns of the disturbance should be considered when predicting the consequences of fragmentation and improving management strategies. 相似文献
13.
Ailemys Curbelo Axel Mancebo Tatiana Molier María E. Arteaga Consuelo González Raiden Grandía 《毒物与环境化学》2013,95(4):691-699
Biological control agents have become a useful alternative for the reduction of the use of chemical insecticides. LABIOFAM (Cuba) is developing a new formulation of a biolarvicide that possesses as active biological agent Bacillus thuringiensis var israelensis serotype H14. In order to evaluate the genotoxicity of this new formulation, an in vivo battery test was used: micronucleus (MN), chromosome aberrations (CAs), and sperm morphology (SM) assays. A dose of 6.45?×?108 spores was administered per animal via oral administration. Bone marrow cells were collected 24?h after a two day treatment for the MN assay, and 24?h after a unique treatment for the CA assay, using cyclophosphamide as the positive control. Sperm cells were collected at 5 weeks from the first of five administrations for the SM test, using acrylamide as positive control. Bacillus thuringiensis var israelensis serotype H14 failed to show either a significative increase of micronucleated polychromatic erythrocytes, chromosomal aberrations, or sperm abnormalities. Acute oral administration of a high dose of Bacillus thuringiensis var israelensis serotype H14 did not produce mutagenic effects in bone marrow or sperm cells. 相似文献
14.
Total concentration and chemical forms of heavy metals in samples of sediment from a drinking water reservoir have been analysed. The result of total metal contest shows Fe and Mn concentration increase along the reservoir, from 4.4% in Fe and 0.07% in Mn in the end part to 6.4% Fe and 0.22% Mn at the dam. However, a decrease in organic matter along the reservoir is observed. In order to test the accuracy of the digestion methods used, a standard reference material was also analysed. Trace metal concentrations, with exception of Cadmium, Pb and Mn, found in fraction 5 are higher than those observed in the others extractions, Fe, Ni, Zn, Cr and Cu content in non‐residual fraction is found mainly in moderately reducible fraction, but the percentage of this fraction in each metal is very different. 相似文献
15.
A new type of dispenser for slow-release of sex pheromones and other semiochemicals was developed based on sol–gel polymers
that can be useful for monitoring, mass trapping, and mating disruption in integrated pest management (IPM). Sol–gel matrices
exhibit glass characteristics and allow control of the degree of cross-linking during the polymerization process in order
to provide an optimal release rate for a particular pheromone. The advantages of sol–gel (silica) matrixes include keeping
the added molecules chemically stable and enabling the sol–gel material to be applied in any desired thickness and pheromone
quantity, and thereby readily modify release rates. In addition, sol–gels are primarily silica and water that are common in
the environment and therefore safe for field dispensing. We developed a method for the entrapment of pheromones in sol–gel
matrices that allowed release at an almost constant rate over many days in the field. For example, 2.5 mg (E)-5-decenyl acetate pheromone of peach twig borer, Anarsia lineatella, entrapped in various sol–gel formulations released 14–45 μg/day for up to 28 days. The codling moth (Cydia pomonella) pheromone in sol–gels was used in field tests to capture more codling moth males than unbaited control traps. We describe
how the method may be modified to entrap other types of pheromones by making sol–gels with different pore sizes. 相似文献
16.
To investigate the chemical composition of the fungus Daldinia eschscholtzii, the compounds were separated by silica gel, Sephadex LH-20, and preparative chromatography. Their structures were identified by spectral methods. The MTT method was applied to measure the cytotoxicity of representative components. Eleven compounds were isolated and identified as 3β-hydroxyl-6,22-dien-5α,8α-peroxynitrite (1); ergosterol-9(11)-dehydroperoxide (2); mangiferonic acid (3); ergosta-4,6,8 (14),22-tetraen-3-one (4); (+)-syringaresinol (5); 3,5,3',5'-tetramethoxy-4,4,-diphenol (6); 5-methoxycoumarin (7); 5-hydroxy-2-methyl-4H-chromen-4-one (8); (2R,4R)-3,4-dihydro-5-methoxy-2-methyl-2H-1-benzopyran-4-ol (9); 2,3-dihydro-5-methoxy-2-methylchromen-4-one (10); and 7β-caruilignan C (11), respectively. Compound 4 showed inhibitory activity against H1299, H460, HGC-27, A5491, and MNK-45, with the IC50 value of 25.2 ± 2.9, 32.3 ± 4.2, 29.2 ± 1.2, 33.9 ± 3.7, and 18.0 ± 7.0 μmol/L, respectively. © 2018 Science Press. All rights reserved. 相似文献
17.
With the development of rural pollution, its characteristic and institutional factor should be studied for pollution control through economics and sociology. Based on the data gathered from investigations by several government sectors, rural environmental pollution can be divided into two types by its sources: internal source type and external source type. The internal source type is the main component of rural pollution at present, which can be further divided into three types. Research shows that the contributing institutional factors of rural pollution issues and the effectiveness of environmental management system over rural pollution can be summarized as distinctiveness. In essence, the rural pollution issue results from the dualism of rural and urban areas’ inadaptability to rural modernization. In detail, the contributing factors can be summed up on three institutional levels. There are obvious loopholes in rural environmental management system which, in the meantime, is incapable and inadaptable to rural pollution control. There exist similar questions in the related public service system, which are intensified by inappropriate reform which brought about incompatible incentive in the recent years. However, in the eleventh five-year plan period, there are advantageous trends in the three institutional levels. 相似文献
18.
SANJIB Kumar Das DIBYENDU Biswas SUDIPTO Roy 《应用与环境生物学报》2007,13(5):662-667
The benthic macroinvertebrate communities of two lotic aquatic habitats,namely,the Churni River(C-R)and the Jalangi River(J-R)were compared in this study.One lotic aquatic system(C-R)was polluted by organic pollutants due to discharge of unprocessed sewage water,while the other(J-R)was not affected by such pollution.Evaluations of various physico-chemical properties of water,sediment and different macroinvertebrate communities of the two tropical lotic systems were done in a period from January,2002 to December,2003.A long term temporal change in the macroinvertebrate communities was recorded due to increase in sediment rH value.Sediment redox potential affected by the anthropogenic activities was found to be an important factor for alteration of macroinvertebrate communities in these aquatic ecosystems.A positive correlation has been established between rH and Margalef index in this study.Potassium and the total count of coliform bacteria in water showed significantly higher values for the polluted Churni River than those for the Jalangi River.Fig 3,Tab 4,Ref 34 相似文献
19.
The ascidian species Ciona intestinalis is a major model chordate in developmental and evolutionary biology, and an important fouling organism and invasive species. However, genomic investigation has recently revealed the existence of two cryptic species, genetically distinct yet without obvious morphological differences, currently referred to as types A and B. Here, we show that they are externally distinctive in a zone of sympatry in the western English Channel. Examining genotyped specimens, we found that types A and B of C. intestinalis can generally be distinguished by body colour, pigmentation at the distal end of the siphons and the presence or absence of tubercles on the sides of the siphons. Detecting specimens of hybrid descent still requires detailed molecular analysis, but these visual characters in combination will identify living specimens of types A and B with high probability. These differences are shown to be inherited. 相似文献
20.
Guy D. Griffin Clay E. Easterly Isidor Sauers Harry W. Ellis Loucas G. Christophorou 《毒物与环境化学》2013,95(2):139-166
Sulfur hexafluoride decomposed by electrical sparks has been found to by cytotoxic to hamster cells when tested in an in vitro cell survival assay, while SF6 shows no cytotoxic activity. Chemical analysis of spark‐decomposed SF6 has identified and quantified the following compounds: SOF2, SO2F2, SF4, SOF4, SiF4, SO2 and HF. Each of these gases, at concentration ranges expected in spark‐decomposed SF6, were tested for cytotoxic activity toward hamster cells. Of the gases showing cytotoxic activity, SO2F2 and SOF4 were similar in activity, as were SOF2 and SF4, while the behavior of SiF4 was different from the rest. None of these individual gases, at concentrations expected in spark‐decomposed SF6, has sufficient cytotoxic activity to account for the cytotoxic effect of spark‐decomposed SF6 observed in our assay system. A four‐component mixture of some of the gases enumerated above (at concentrations overestimating their abundance in spark‐decomposed SF6) was much less cytotoxic than the spark‐decomposed SF6 gas. A mathematical simulation of the cytotoxic activity of a mixture of gases at concentrations found in spark‐decomposed SF6 was made, assuming independent cytotoxic effects from each component. The simulated cytotoxic effect thus computed was less than that seen in spark‐decomposed SF6. Since individual components or mixtures of the major decomposition products do not account for the observed biological activity of spark‐decomposed SF6, this suggests there may be one or more components, present in the spark‐decomposed gas at very low concentrations, which may have a very strong cytotoxic activity. 相似文献