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111.
The success of the rapidly desorbing fraction as an available fraction was challenged by using sediment ingesting and non-ingesting oligochaetes (Lumbriculus variegatus) together with passive samplers (semipermeable membrane devices, SPMDs) in accumulation and kinetic modelling exercises for carbon-14 labelled model compounds (pyrene, benzo[a]pyrene and 3,4,3',4'-tetrachlorobiphenyl). Passive samplers clearly produced lower uptake rate constants and steady state factors than either of the oligochaete treatments when residue concentrations were based on animal lipid or total SPMD weight. The rapidly desorbing chemical fractions in sediments did not show a significant relationship with the biota sediment accumulation factors or SPMD accumulation factors. A distinctly better relationship was observed between the accumulation factors and the desorption rate constants. The results support the assumption that desorption plays an important role in bioavailability, although animal behaviour and the diffusional limitations of hydrophobic contaminants in sediment together probably affect the actual available pool. 相似文献
112.
Degradation of three phenylurea herbicides (chlortoluron, isoproturon and diuron) by micromycetes isolated from soil 总被引:1,自引:0,他引:1
As part of a study conducted on the fate of xenobiotics in the environment, a selection of 100 strains of micromycetes (Ascomycetes, Basidiomycetes and Yeasts) have been cultivated in liquid synthetic medium with 3 phenylurea herbicides: chlortoluron and isoproturon (100mg L-1) and diuron (20mg L-1). While 17 strains depleted isoproturon over 50% only 4 depleted diuron and 2 chlortoluron at the same level. The best results were obtained with Bjerkandera adusta and Oxysporus sp which were the most efficient towards the 3 substrates. After 2 weeks Bjerkandera adusta depleted chlortoluron 98%, diuron 92% and isoproturon 88%. 相似文献
113.
Bioremediation of tributyltin contaminated sediment: degradation enhancement and improvement of bioavailability to promote treatment processes 总被引:1,自引:0,他引:1
Bioremediation of tributyltin (TBT) contaminated sediment was studied and degradation enhancement and improvement of bioavailability were also investigated. In TBT spiked sediment, the half-life of TBT in the control sample, representing natural attenuation, was 578 d indicating its persistence. In the stimulated sample (pH 7.5, aeration and incubated at 28 °C), the half-life was significantly reduced to 11 d. Further stimulation by nutrient addition (succinate, glycerol and l-arginine) or inoculation with Enterobacter cloacae (∼107 viable cells g−1 of sediment) resulted in half-life reduction to 9 and 10 d, respectively. In non-spiked sediment, the indigenous microorganisms were able to degrade aged TBT, but the extended period of contamination decreased the degradation efficiency. To improve bioavailability, addition of surfactant, adjustment of salinity and sonication were studied. The highest percentage solubilisation of TBT in water was obtained by adjusting salinity to 20 psu, which increased the solubility of TBT from 13% to 33%. Half-lives after bioavailability was improved were 5, 4 and 4 d for stimulation, stimulation w/nutrient addition and stimulation w/inoculation, respectively. However, natural attenuation in the control sample was not enhanced. The results show that providing suitable conditions is important in enhancing TBT biodegradation, and bioavailability improvement additionally increased the rate and degraded amount of TBT. Unfortunately, nutrient addition and inoculation of the degrader did not enhance the degradation appreciably. 相似文献
114.
do A Kehrig H Seixas TG Palermo EA Baêta AP Castelo-Branco CW Malm O Moreira I 《Environmental science and pollution research international》2009,16(1):10-24
Background, aim, and scope Selenium (Se) has been shown to reduce mercury (Hg) bioavailability and trophic transfer in aquatic ecosystems. The study
of methylmercury (MeHg) and Se bioaccumulation by plankton is therefore of great significance in order to obtain a better
understanding of the estuarine processes concerning Hg and Se accumulation and biomagnification throughout the food web. In
the western South Atlantic, few studies have documented trace element and MeHg in fish tissues. No previous study about trace
elements and MeHg in plankton has been conducted concerning tropical marine food webs. Se, Hg, and MeHg were determined in
two size classes of plankton, microplankton (70–290 μm) and mesoplankton (≥290 μm), and also in muscle tissues and livers
of four fish species of different trophic levels (Mugil liza, a planktivorous fish; Bagre spp., an omnivorous fish; Micropogonias furnieri, a benthic carnivorous fish; and Centropomus undecimalis, a pelagic carnivorous fish) from a polluted estuary in the Brazilian Southeast coast, Guanabara Bay. Biological and ecological
factors such as body length, feeding habits, and trophic transfer were considered in order to outline the relationships between
these two elements. The differences in trace element levels among the different trophic levels were investigated.
Materials and methods Fish were collected from July 2004 to August 2005 at Guanabara Bay. Plankton was collected from six locations within the bay
in August 2005. Total mercury (THg) was determined by cold vapor atomic absorption spectrometry (CV-AAS) with sodium borohydride
as a reducing agent. MeHg analysis was conducted by digesting samples with an alcoholic potassium hydroxide solution followed
by dithizone-toluene extraction. MeHg was then identified and quantified in the toluene layer by gas chromatography with an
electron capture detector (GC-ECD). Se was determined by AAS using graphite tube with Pin platform and Zeeman background correction.
Results and discussion Total mercury, MeHg, and Se increased with plankton size class. THg and Se values were below 2.0 and 4.8 μg g−1 dry wt in microplankton and mesoplankton, respectively. A large excess of molar concentrations of Se in relation to THg was
observed in both plankton size class and both fish tissues. Plankton presented the lowest concentrations of this element.
In fish, the liver showed the highest THg and Se concentrations. THg and Se in muscle were higher in Centropomus undecimalis (3.4 and 25.5 nmol g−1) than in Micropogonias furnieri (2.9 and 15.3 nmol g−1), Bagre spp (1.3 and 3.4 nmol g−1) and Mugil liza (0.3 and 5.1 nmol g−1), respectively. The trophic transfer of THg and Se was observed between trophic levels from prey (considering microplankton
and mesoplankton) to top predator (fish). The top predators in this ecosystem, Centropomus undecimalis and Micropogonias furnieri, presented similar MeHg concentrations in muscles and liver. Microplankton presented lower ratios of methylmercury to total
mercury concentration (MeHg/THg) (34%) than those found in mesoplankton (69%) and in the muscle of planktivorous fish, Mugil liza (56%). The other fish species presented similar MeHg/THg in muscle tissue (of around 100%). M. liza showed lower MeHg/THg in the liver than C. undecimalis (35%), M. furnieri (31%) and Bagre spp. (22%). Significant positive linear relationships were observed between the molar concentrations of THg and Se in the
muscle tissue of M. furnieri and M. liza. These fish species also showed significant inverse linear relationships between hepatic MeHg and Se, suggesting a strong
antagonistic effect of Se on MeHg assimilation and accumulation.
Conclusions Differences found among the concentrations THg, MeHg, and Se in microplankton, mesozooplankton, and fishes were probably related
to the preferred prey and bioavailability of these elements in the marine environment. The increasing concentration of MeHg
and Se at successively higher trophic levels of the food web of Guanabara Bay corresponds to a transfer between trophic levels
from the lower trophic level to the top-level predator, suggesting that MeHg and Se were biomagnified throughout the food
web. Hg and Se were positively correlated with the fish standard length, suggesting that larger and older fish bioaccumulated
more of these trace elements. THg, MeHg, and Se were a function of the plankton size.
Recommendations and perspectives There is a need to assess the role of selenium in mercury accumulation in tropical ecosystems. Without further studies of
the speciation of selenium in livers of fishes from this region, the precise role of this element, if any, cannot be verified
in positively affecting mercury accumulation. Further studies of this element in the study of marine species should include
liver samples containing relatively high concentrations of mercury. A basin-wide survey of selenium in fishes is also recommended. 相似文献
115.
Nutrient accumulation in trees and soil following irrigation with municipal effluent in Australia 总被引:2,自引:0,他引:2
Stewart HT Hopmans P Flinn DW Hillman TJ 《Environmental pollution (Barking, Essex : 1987)》1990,63(2):155-177
Irrigation of tree crops is being evaluated as a method of land disposal of municipal effluent in Australia. A study was carried out from 1980-84 in which seven tree species were sprinkler-irrigated with effluent at an annual rate of 1191-1752 mm. Effective weed control and frequent irrigation resulted in good survival of all species (range 83-100%) at 12 months. Total productivity was estimated at age 4 years by measuring biomass of each species inclusive of litter and roots to a soil depth of 80 cm. Biomass production of the high-yielding species, flooded gum (Eucalyptus grandis) and Sydney blue gum (E. saligna), was around 10 kg m(-2). Percentage leaf mass of these species was small (8-9%) compared with 25% and 29% for the relatively slow-growing river she-oak (Casuarina cunninghamiana) and radiata pine (Pinus radiata). Accumulation of nutrients in the total biomass differed significantly between species and ranged from 34-54 g m(-2) for nitrogen, 4.0-10.4 g m(-2) for phosphorus, 2.1-12.2 g m(-2) for sodium, 22-34 g m(-2) for potassium, 12-61 g m(-2) for calcium and 4.7-9.3 g m(-2) for magnesium. River she-oak and river red gum (E. camaldulensis), because of their relatively large crown and litter masses, accumulated more nitrogen, phosphorus, potassium and calcium than flooded gum or Sydney blue gum. Chemical properties of soils (0-150 cm) were measured in 1980 and again in 1984. Irrigation significantly increased pH (by around 1 unit), throughout the profile. Concentrations of total phosphorus, and exchangeable sodium, calcium and magnesium were increased in the upper profile. Overall, soil chemical properties were not adversely affected by effluent irrigation over the 4-year period, though there was a trend towards more sodic conditions in the soil profile. Nutrient accumulation in soil occurred mainly in the 0-35 cm depth, coinciding with the main root zone of the trees. Renovation of the effluent was therefore estimated as the amount of each nutrient accumulated in the biomass (averaged over the seven species) plus soil (0-35 cm), expressed as a percentage of amount applied in irrigation over the 4 years; that is, nitrogen, 29%; phosphorus, 78%; sodium, 15%; potassium, 26%; calcium, 98% and magnesium, 54%. 相似文献
116.
117.
An overview of the methods used in the characterisation of natural organic matter (NOM) in relation to drinking water treatment 总被引:9,自引:0,他引:9
Matilainen A Gjessing ET Lahtinen T Hed L Bhatnagar A Sillanpää M 《Chemosphere》2011,83(11):1431-1442
Natural organic matter (NOM) is found in all surface, ground and soil waters. During recent decades, reports worldwide show a continuing increase in the color and NOM of the surface water, which has an adverse affect on drinking water purification. For several practical and hygienic reasons, the presence of NOM is undesirable in drinking water. Various technologies have been proposed for NOM removal with varying degrees of success. The properties and amount of NOM, however, can significantly affect the process efficiency. In order to improve and optimise these processes, the characterisation and quantification of NOM at different purification and treatment processes stages is important. It is also important to be able to understand and predict the reactivity of NOM or its fractions in different steps of the treatment. Methods used in the characterisation of NOM include resin adsorption, size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) spectroscopy, and fluorescence spectroscopy. The amount of NOM in water has been predicted with parameters including UV-Vis, total organic carbon (TOC), and specific UV-absorbance (SUVA). Recently, methods by which NOM structures can be more precisely determined have been developed; pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), multidimensional NMR techniques, and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). The present review focuses on the methods used for characterisation and quantification of NOM in relation to drinking water treatment. 相似文献
118.
Effects of bis(tributyltin)oxide on antipredator behavior in threespine stickleback Gasterosteus aculeatus L. 总被引:1,自引:0,他引:1
Antipredator behavior was used as a parameter to detect effects caused by exposure to the organotin compound bis(tributyltin)oxide (TBTO). Three groups of threespine sticklebacks (Gasterosteus aculeatus L.) were exposed to 3, 9 and 27 ppb TBTO, respectively. A fourth control group was given the same treatment as the other three groups, but no TBTO. Antipredator behavior of the fish was evoked using a dummy heron (Ardea cinerea) bill. TBTO exposure caused significant changes in the spatial position of the fish in the aquarium (P(Loc)), their response to predator attack (P(Res)), recovery time (P(Rec)) and latency time (P(Lat)). Some of the effects were, however, reversible after the exposure was terminated. We suggest that behavior as an indicator of pollution may be used as an ecologically relevant integrative biomarker. 相似文献
119.
Polycyclic aromatic hydrocarbons in the bulk precipitation and surface waters of Northern Greece 总被引:15,自引:0,他引:15
Bulk (wet and dry) precipitation and surface water sampling was undertaken in the main plain of central Macedonia in Northern Greece. Fourteen polycyclic aromatic hydrocarbons (PAHs) included in the US EPA's priority pollutant list were analysed. The concentrations determined in bulk precipitation were in general within the range of values worldwide reported. Concentrations were highest in the cold months. Deposition fluxes of PAHs were of the same order of magnitude as reported data. The greatest values were found when high concentrations of PAHs in precipitation coincided with large precipitation amounts. The concentrations of PAHs in surface waters (main rivers, tributaries, ditches, etc) were in general lower than those in bulk precipitation, and among the lowest reported for European rivers, excepting Np and Ph. Bulk deposition and domestic effluents are suggested as being the main PAH sources into surface waters. 相似文献
120.
Means to improve the effect of in situ bioremediation of contaminated soil: an overview of novel approaches 总被引:16,自引:0,他引:16
Romantschuk M Sarand I Petänen T Peltola R Jonsson-Vihanne M Koivula T Yrjälä K Haahtela K 《Environmental pollution (Barking, Essex : 1987)》2000,107(2):179-185
Different aspects of bacterial degradation of organic contaminants in soil, and how to improve the efficiency and reproducibility is discussed in this review. Although bioremediation in principle includes the use of any type of organism in improving the condition of a contaminated site, most commonly bacteria are the degraders and other organisms, such as soil animals or plant roots, play a role in dissemination of bacteria and, indirectly, plasmids between bacteria, and in providing nutrients and co-substrates for the bacteria active in the degradation process. There are a number of different procedures that have been tested more-or-less successfully in attempts to improve reliability, cost efficiency and speed of bioremediation. The methods range from minimal intervention, such as mere monitoring of intrinsic bioremediation, through in situ introduction of nutrients and/or bacterial inocula or improvement of physico-chemical conditions, all the way to excavation followed by on site or ex situ composting in its different varieties. In the past the rule has been that more intervention (leading to higher costs) has been more reliable, but novel ideas are continuously tried out, both as a means to come up with new truly functional applications and also as a line of studies in basic soil microbial ecology. Both approaches generate valuable information needed when predicting outcome of remediation activities, evaluating environmental risks, deciding on cleaning-up approaches, etc. The emphasis of this review is to discuss some of the novel methods for which the value has not been clearly shown, but that in our view merit continued studies and efforts to make them work, separately or in combination. 相似文献