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1.
Christina L. L?jtnant Birte Boelt Sabine K. Clausen Christian Damgaard Per Kryger Ari Novy Marianne Philipp Cathrine H. Ingvordsen Rikke Bagger J?rgensen 《Environmental Modeling and Assessment》2012,17(4):421-430
The portion-dilution model is a parametric restatement of the conventional view of animal pollination; it predicts the level of pollinator-mediated gene dispersal. In this study, the model was applied to white clover (Trifolium repens) and its most frequent pollinator, the honeybee (Apis mellifera). One of the three parameters in the portion-dilution model is the mean number of flowers a pollinator visits in one foraging bout. An alternative method to estimate this parameter was developed that was not depending on pollinator hive-seeking behaviour. The new estimation method, based on nectar collection, seems to be a good alternative, when reliable observation on visiting behaviour of pollinators is not possible. The gene flow in white clover was modelled. Where fields were assumed to be well separated, and only a low fraction of bees travelled between fields, the gene flow was estimated to be 0.7%, but subjected to large uncertainty. In a worst case scenario with adjacent fields—one with a genetically modified (GM) T. repens cultivar and the other with a conventional T. repens cultivar—and where all arriving bees were expected to transfer GM pollen, the median gene flow was modelled to be 7% with an estimated 95% percentile of 70%. The results show that the European Union threshold limit of 0.9% GM admixture for food and feed will likely be exceeded at times and especially organic farmers that do not accept GM admixture and often have clover and clover–grass fields might face challenges with admixture of GM. 相似文献
2.
Computational Fluid Dynamics Modelling of the Pollution Dispersion and Comparison with Measurements in a Street Canyon in Helsinki 总被引:1,自引:0,他引:1
P. Neofytou M. Haakana A. Venetsanos A. Kousa J. Bartzis J. Kukkonen 《Environmental Modeling and Assessment》2008,13(3):439-448
A measuring campaign was conducted in a street canyon (Runeberg St.) in Helsinki in 2003–2004. The concentrations of NO
x
, NO2, PM10 and PM2.5 were measured at street level and at roof level at an urban background location. This study utilises the data measured from
1 Jan to 30 April, 2004, when wind speed and direction measurements were also conducted on-site at the roof level. The computational
fluid dynamics model ADREA-HF was used to compute the street concentrations, and the results were compared with the measurements.
The predictions for the selected cases agreed fairly well (within < 25 % for 15 min average values) with the measured data,
except for two cases: a windward flow in case of a low wind speed, and a moderate southerly flow parallel to the street canyon.
The main reasons for the differences of predictions and measurements are the negligence of traffic-induced turbulence in the
modelling and an under-prediction of ventilation of urban background air from a crossing street. Numerical results are presented
for various example cases; these illustrate the formation of the vortices in the canyon in terms of the wind direction and
speed and the influence of the characteristics of the flow fields on the concentration distributions. 相似文献
3.
This study deals with numerical simulation of flow fields and dispersion of model passive admixtures in the planetary boundary
layer in a 10 × 10 km square area, centered on the Czech Republic’s Temelín Nuclear Power Plant. Numerical calculations of
three-dimensional flow fields with eight basic wind directions given for the inlet boundary of the computational domain are
performed using the FLUENT CFD code with the standard k – ε turbulence model. The resultant modeling of the flow fields provides information as to probable local directions and velocities
of flow vectors on a horizontal scale of 100 m, which are consistent with the data given for the boundaries of the calculation
area in the framework of a scale of 10 km. The modeled flow fields generate the input data for related Lagrangian simulation
of the ground concentration and deposition fields of passive particles assumedly emitted at the site of the Temelín plant.
Simulated plumes describe eight cases of potential ground-level distribution of model passive admixtures in the area. 相似文献
4.
Citation of cyanobacterial cultures from the shores of south west coast of Gujarat, India and their relationship with sea water quality, influenced by extensive pollutant runoff is reported in this study. Intensity of pollution was evaluated by physico-chemical analysis of water. Higher load of suspended solids (60–1000 mg l−1) and nutrients (PO4
−P: 1.3–4 μmole l−1 and NO3
−N: 12.5–17.8 μmole l−1) were persistent throughout the analysis. Community structure is seen to be influenced by such persistent pollution. Twenty nine cyanobacterial species were isolated belonging to 9 genera of 4 families, with an elevated occurrence of Oscillatoria and Lyngbya species. No heterocystous cyanobacteria were isolated throughout the study. 相似文献
5.
Assessment of the exposure of two fish species to metals pollution in the Ogun river catchments, Ketu, Lagos, Nigeria 总被引:1,自引:0,他引:1
The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water,
sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking
water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations
are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels
of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences
were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all
six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments
are within the range reported for Nigeria’s river sediments. Based on this study, the human risks for heavy metals in the
harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended
Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish. 相似文献
6.
Native trout species, such as the redband trout (Oncorhynchus mykiss), occupy thermally harsh stream habitats in hot, arid rangeland basins of the western United States. Declines in the distribution
and abundance of these species has generated interest in understanding how these cold water species survive in these systems,
as well as in identifying opportunities to restore these species to their former ranges. The purpose of this study was to
assess the potential for thermal stratification to provide thermal refuge for redband trout in stream pools characterized
by warm intermittent flow conditions on arid rangelands. We studied vertical thermal stratification in two pools during three
summers on Boles Creek located on the Modoc Plateau in extreme northeastern California. Water and air temperature data were
collected on a 0.5 h time step from 15-Jun through 15-Sep during 1996, 1997, and 2000 using commercial temperature data-loggers.
Water temperature was measured at the top (0.3 m below pool surface) and bottom (0.3 m above pool substrates) of each pool.
Vertical thermal stratification occurred within these pools creating conditions as much as 7.6 ˚C cooler and consistently
more constant at the bottom of pools compared to pool surface waters. Thermal stratification was dependent upon air temperature
with the magnitude of stratification increasing as air temperature increased. The magnitude of thermal stratification varied
significantly from year to year, likely reflecting variation in annual weather conditions. The thermal regime in the study
pools was often near the upper lethal limit reported for redband trout, but temperatures at the bottom of these pools did
offer refuge from lethal temperatures realized near the pool surface. Temperatures at pool bottom were consistently above
optimal levels published for redbands. 相似文献
7.
Hijano CF Domínguez MD Gimínez RG Sínchez PH García IS 《Environmental monitoring and assessment》2005,111(1-3):75-88
The evaluation of certain vascular plants that grow in the city of Madrid as biomonitors of SO2 air pollution in urban environments has been carried out. Total concentration of sulphur in leaves of the chosen higher plants
as well as other parameters in close relation to this contaminant (visible injury symptoms, chlorophyll a- and b-content and
peroxidase activity) have been determined in order to study the spatial distribution and temporal changes in SO2 deposition. Results obtained show that coniferous species such as Pinus pinea, were more sensitive to SO2 atmospheric concentration than leafy species as Quercux ilex subspecies ballota and, in the same way, bush species, such asPyracantha coccinea and Nerium oleander, were more sensitive than wooded species, such as Cedrus deodaraandPinus pinea, respectively. There is a higher accumulation of sulphur in vegetable species located near highways and dense traffic incidence
roads and near areas with high density of population. The minimum values for accumulation of SO2 were registered in winter and spring seasons (from January to April) due to the vegetative stop; while maximum values are
obtained during the summer season (from June to September), due to the stoma opening. The highest increments in sulphur concentration,
calculated as the difference between two consecutive months, are obtained in May and June for all considered species except
forCedrus deodara and Pyracantha coccinea, both species have few seasonal changes during the whole year. Some species are more sensitive to natural washing than others,
showing a decrease in sulphur concentration after rainfall periods. 相似文献
8.
Wigand C McKinney RA Cole ML Thursby GB Cummings J 《Environmental monitoring and assessment》2007,131(1-3):71-81
The stable nitrogen isotope ratios of some biota have been used as indicators of sources of anthropogenic nitrogen. In this
study the relationships of the stable nitrogen isotope ratios of marsh plants, Iva frutescens (L.), Phragmites australis (Cav.) Trin ex Steud, Spartina patens (Ait.) Muhl, Spartina alterniflora Loisel, Ulva lactuca (L.), and Enteromorpha intestinalis (L.) with wastewater nitrogen and land development in New England are described. Five of the six plant species (all but U. lactuca) showed significant relationships of increasing δ
15N values with increasing wastewater nitrogen. There was a significant (P < 0.0001) downward shift in the δ
15N of S. patens (6.0 ± 0.48‰) which is mycorrhizal compared with S. alterniflora (8.5 ± 0.41‰). The downward shift in δ
15N may be caused by the assimilation of fixed nitrogen in the roots of S. patens. P. australis within sites had wide ranges of δ
15N values, evidently influenced by the type of shoreline development or buffer at the upland border. In residential areas,
the presence of a vegetated buffer (n = 24 locations) significantly (P < 0.001) reduced the δ
15N (mean = 7.4 ± 0.43‰) of the P. australis compared to stands where there was no buffer (mean = 10.9 ± 1.0‰; n = 15). Among the plant species, I. frutescens located near the upland border showed the most significant (R
2 = 0.64; P = 0.006) inverse relationship with the percent agricultural land in the watershed. The δ
15N of P. australis and I. frustescens is apparently an indicator of local inputs near the upland border, while the δ
15N of Spartina relates with the integrated, watershed-sea nitrogen inputs. 相似文献
9.
Forage and soil molybdenum (Mo) were measured in the vicinity of a Mo processing plant in southwestern Pennsylvania, USA. Molybdenum concentrations in red clover plants (Trifolium pratense L.), measured at 23 sites, ranged from 1.1 to 56.6 mg kg–1. Fourteen of the 23 sites sampled had red clover plants with Mo concentrations over the threshold value of 6 mg kg–1. Red clover Cu:Mo concentration ratios were below the recommended ratio of 4 in 19 of the sites. The low Cu:Mo values, along with high plant Mo concentrations, indicates that there is a potential risk of molybdenosis in ruminant animals in this area. Acid digested (sorbed) soil Mo concentrations, measured at 30 sites, ranged from 7.0 (background level) to 131 mg kg–1. Using the Baker Soil Test (BST) extract, molybdenum soil concentrations ranged from 0.01 to 3.99 mg kg–1. Regression equations were developed to predict plant uptake of soil Mo based on the red clover plant, soil extracts and soil pH data. The R-squared values for predicting plant uptake were 81.9% for the BST extract and 81.6% for the acid digestion extract plus soil pH. Based on the above results, a protocol has been implemented for assessing the risk of high soil Mo near this Mo processing plant. 相似文献
10.
Nagler P Glenn EP Hursh K Curtis C Huete A 《Environmental monitoring and assessment》2005,109(1-3):255-274
A vegetation mapping system for change detection was tested at the Havasu National Wildlife Refuge (HNWR) on the Lower Colorado
River. A low-cost, aerial photomosaic of the 4200 ha, study area was constructed utilizing an automated digital camera system,
supplemented with oblique photographs to aid in determining species composition and plant heights. Ground-truth plots showed
high accuracy in distinguishing native cottonwood (Populus fremontii) and willow (Salix gooddingii) trees from other vegetation on aerial photos. Marsh vegetation (mainly cattails, Typha domengensis) was also easily identified. However, shrubby terrestrial vegetation, consisting of saltcedar (Tamarix ramosissima), arrowweed (Pluchea sericea), and mesquite trees (Prosopis spp.), could not be accurately distinguished from each other and were combined into a single shrub layer on the final vegetation
map. The final map took the form of a base, shrub and marsh layer, which was displayed as a Normalized Difference Vegetation
Index map from a Landsat Enhanced Thematic Mapper (ETM+) image to show vegetation intensity. Native willow and cottonwood
trees were digitized manually on the photomosaic and overlain on the shrub layer in a GIS. By contrast to present, qualitative
mapping systems used on the Lower Colorado River, this mapping system provides quantitative information that can be used for
accurate change detection. However, better methods to distinguish between saltcedar, mesquite, and arrowweed are needed to
map the shrub layer. 相似文献
11.
Seasonal aerosol samples have been collected by Andersen Hi-Vol pumping system equipped with a five stage cascade impactor
and a backup filter (size range: 10–7.2 μ m, 7.2–3.0 μ m, 3.0–1.5 μ m, 1.5–0.95 μ m, 0.95–0.49 μ m, ≤0.49 μ m) in the Liwan
district, Guangzhou. n-Alkanes were measured using gas chromatography and PAHs were measured using gas chromatography/mass spectrometry analysis.
The bimodal log-normal distributions of n-alkanes and semi-volatile PAHs were found, while for non-volatile PAHs that was unimodal, so much as the mode of semi-volatile
PAHs was similar with that of the particles. The n-alkanes and PAHs were preferably associated with fine particles. C
max (carbon number maximum) (C22–C26), CPI (carbon preference index) (1.12–1.21), U/R (unresolved to resolved components ratio) (7.42–10.7), wax% (0.9–3.12%)
and the diagnostic ratios for PAHs revealed that vehicular emission was the major source of these organic compounds during
the study periods, while the contribution of epicuticular waxes emitted by terrestrial plants was minor. CPI2 (values for petrogenic hydrocarbons), CPI3 (values for biogenic n-alkanes) and wax% revealed that the natural preferentially accumulated in the larger aerosol while the anthropogenic in the
smaller. In addition, the different MMDs (mass median diameters) for n-alkanes and PAHs were observed in different seasons. The MMDs for n-alkanes and PAHs were higher in autumn/winter than those in spring/summer. The seasonal effect was related to the hydrocarbon
content in the individual particulate fractions, showing a preferential association of n-alkanes and PAHs with larger particles in the autumn/winter season. 相似文献
12.
Field experiment on 10 ha area of fly ash dump was conducted to restore and revegetate it using biological interventions,
which involves use of organic amendment, selection of suitable plant species along with specialized nitrogen fixing strains
of biofertilizer. The results of the study indicated that amendment with farm yard manure at 50 t/ha improved the physical
properties of fly ash such as maximum water holding capacity from 40.0 to 62.42% while porosity improved from 56.78 to 58.45%.
The nitrogen content was increased by 4.5 times due to addition of nitrogen fixing strains of Bradyrhizobium and Azotobacter species, while phosphate content was increased by 10.0 times due to addition of VAM, which helps in phosphate immobilization.
Due to biofertilizer inoculation different microbial groups such as Rhizobium, Azotobacter and VAM spores, which were practically absent in fly ash improved to 7.1 × 107, 9.2 × 107 CFU/g and 35 VAM spores/10 g of fly ash, respectively. Inoculation of biofertilizer and application of FYM helped in reducing
the toxicity of heavy metals such as cadmium, copper, nickel and lead which were reduced by 25, 46, 48 and 47%, respectively,
due to the increased organic matter content in the fly ash which complexes the heavy metals thereby decreasing the toxicity
of metals. Amendment of fly ash with FYM and biofertilizer helped in profuse root development showing 15 times higher growth
in Dendrocalamus strictus plant as compared to the control. Thus amendment and biofertilizer application provided better supportive material for anchorage
and growth of the plant. 相似文献
13.
This study aimed to optimise the methodology for the use of Corophium insidiosum in a bioassay. Taking into account that it would be suitable to execute the bioassay with organisms having a good sensitivity
during the year and low mortality in control sediment, the influence of different temperatures (10–15–20 and 25°C) has been
examined. C. insidiosum was collected during August, November 2005 and January 2006, in Mar Piccolo basin (Ionian sea). The results obtained show
that this species mortality in the negative control sediment, ranged from 2.6 ± 0.6% at 10°C in August to 17 ± 2.2% at 20°C
in November, at different temperatures tested. At 20°C there were significant differences in mortality among different months
examined. Indeed no relationship among months was found at 15°C. Significant differences between August and November at 25°C,
between November and January were not found at 10°C. The 96-h LC50 values found for cadmium at all temperature experimental
conditions ranged from 2.11 mg/l (1.57–2.82) to 0.70 mg/l (0.54–0.93). The highest values were found at 10°C in November and
January. The results showed that the optimal temperature for the bioassay seems to be between 15°C and 20°C. Even if, at 20°C
the mortality differs significantly among organisms sampled. 相似文献
14.
Biomonitoring dissolved heavy metals within estuaries,particularly at their upper reaches, frequently has to relyon several biomonitors; rarely a single species thrives allalong the salinity gradient. To properly do so, it must beestablished whether those biomonitors actually accumulateheavy metals alike. In this study, two brown seaweeds fromthe upper section of three NW Spain estuaries – the widely-known Fucus vesiculosus and the estuarine Fucusceranoides – were compared as metal biomonitors. Bothspecies were collected at five locations where they eithercoexist or live close to each other and their heavy metalcontent (Cu, Cr, Mn, Zn, Fe, Al) was measured. Analyseswere appropriately replicated for each species x locationcombination to allow a statistically reliable detection ofdifferences in bioaccumulation, with particular emphasis onthe magnitude of interspecific differences. The lack of significant differences for Cu, Mn, and Zncontents in F. ceranoides and F. vesiculosussupports the feasibility of their joint use to monitorthese metals along the estuaries. Conversely, F.ceranoides concentrated significantly higher levels of Cr,Fe, and Al than F. vesiculosus and hence combiningdata for both fucoids to monitor these elements seemsimpractical. The correlation of species differencestogether with a similar Al:Fe ratio in both weed tissue andsediment suggest that Cr, Fe, and Al tissue-burdens mightbe considerably biased by sediment retained on the surfaceof the weed. Parallel analyses of Al and/or Fe in seaweedsand sediments could serve to keep track of thisinterference and may help to combine data from both fucoidsfor monitoring elements like Cr. 相似文献
15.
N. Moussiopoulos Ph. Barmpas I. Ossanlis J. Bartzis 《Environmental Modeling and Assessment》2008,13(3):357-368
Towards the aim of improving the air quality in the urban environment via the application of innovative TiO2 based photocatalytic coverings, a field campaign took place within the frame of the EU PICADA project () to asses the expected depollution efficiency of such materials under realistic conditions. Furthermore, extensive numerical
modeling was performed via the application of the RANS CFD code for microscale applications MIMO, in an effort to asses the
sensitivity of the developing flow field and the corresponding dispersion mechanism and hence of the depollution efficiency
of the PICADA products on a wide range of factors, with most notably the length of the street canyon, the thermal exchange
between the heated street canyon walls and the air and the approaching wind direction. For the needs of the PICADA project
a new, simple module had to be implemented into MIMO to be able to model the removal of NOx from a street canyon whose walls have been treated with a photocatalytic product. The model simulations results presented
in this paper, show that MIMO is indeed capable of predicting the effectiveness of the photocatalytic products in question.
At the same time, they reveal a strong dependence of the developing flow and concentration fields inside the field site street
canyon configuration on most of the aforementioned factors with most notably the direction of the approaching wind.
相似文献
N. MoussiopoulosEmail: |
16.
Clifford A. Hui John Y. Takekawa Sarah E. Warnock 《Environmental monitoring and assessment》2001,71(2):107-121
The San Francisco Bay estuary isused by over one million shorebirds during springmigration and is home to several hundred thousandduring the winter. Most shorebird use occurs in thesouthern reach of the estuary (South Bay). Thereduced water circulation and discharge fromindustrial sources in the South Bay are responsiblefor the highest levels of some trace elements in theestuary. Wintering shorebirds have been found to havestrong site fidelity to areas as small as a fewkilometers in the South Bay, which may increase theirexposure to contaminants near local point sources. Inaddition, different shorebird species foraging at thesame site have been shown to have differentcontaminant burdens. Thus, our objectives were totest whether contaminant burdens differed by species,or whether contaminant burdens differed in shorebirdscollected at adjacent sites. We examined thecontaminant profiles of two species of shorebirds,long-billed dowitchers (Limnodromus scolopaceus)and western sandpipers (Calidris mauri) thatforage together at two sites, Hayward and Newark,separated by 8 km in the South Bay. We usedmultivariate analysis of variance tests to compare thecomposition of 14 elemental analytes in their livertissues and estimated their molar ratios of Hg and Se. Composite samples were used for contaminant analysesbecause of the small body size of the shorebirds. Seven elemental analytes (Ag, Ba, Be, Cr, Ni, Pb, V)were below detection limits in a majority of thesamples so statistical analyses were precluded. Inthe measurable analytes (As, Cd, Cu, Hg, Mn, Se, Zn),we found no significant intra-site differences ofcontaminant profiles for the two species. We pooledthe samples to examine inter-site differences andfound significant differences in contaminant profilesbetween shorebirds at the neighboring sites (P = 0.03). Shorebirds at Newark had higher (P < 0.05) concentrations of As, Cd, and Se than those at Hayward. Dowitchers at Newark had concentrations of Hg and Se which were highly correlated (P < 0.003) in a mean molar ratio of 1:19, similar tothat reported in other birds. In the larger dowitcherspecies, we also examined exposure to 20organochlorine compounds. Organic analyses showedthat the dowitchers had been exposed to DDE, PCBs,dieldrin and trans-nonachlor, but with no significantdifferences in concentrations between Hayward andNewark (P > 0.05). 相似文献
17.
Delta-aminolevulinate dehydratase (ALAD) activity has been used in prokaryotes and eukaryotes as a biomarker for environmental
lead (Pb) exposure and toxicity. Microorganisms are sensitive indicators of toxicity at the fundamental level of ecological
organization, but bacterial biomarker studies are focused on the Pseudomonas strains in Group I and E coli. The objectives of the present work were to determine if Burkholderia gladioli belonging to group II, due to its 16SrRNA similarity, can be used as biomarker in metal contamination and compare its possible
usage with Pseudomonas aeruginosa and Citrobacter freundii (previously known as Esherichia freundii) and Bacterium freundii which are classified in Group I. In this study, ALAD activity in an environmental strains of Burkholderia gladioli, Pseudomonas aeruginosa, Citrobacter freundii were investigated to evaluate potential inhibition by Pb and other toxic metals. When the ALAD activity of Burkholderia gladioli was tested, Co and Pb decreased activity by 27 and 71%, respectively. In addition to these findings, Zn increased the activity
up to 26%. These effects were found to be statistically meaningful (p < 0.05). It was determined that the increase of lead concentration inhibites the ALAD activity at each of the three strains.
There was a statistically significant dose–response relationship between ALAD activity in cells of Burkholderia gladioli and Pb (Pearson correlation coefficent = −0.665; r
2 = 0.665, and p < 0.001). The strongest ALAD inhibition which was measured was 90% at Burkholderia gladioli when protein extracts were incubated with 750 μM of Pb. The relationship between Pb and ALAD activity was statistically described
by [ALAD Activity] = 0.476−0.000597 × [Pb]. According to the obtained results, we suggest that the ALAD of Burkholderia gladioli can be used as a biomarker for lead contamination in the environment. 相似文献
18.
Wind erosion selectively winnows the fine, most chemically concentrated portions of surface soils and results in the inter-regional
transport of fugitive dust containing plant nutrients, trace elements and other soil-borne contaminants. We sampled and analyzed
surface soils, sediments in transport over eroding fields, and attic dust from a small area of the Southern High Plains of
Texas to characterize the physical nature and chemical constituents of these materials and to investigate techniques that
would allow relatively rapid, low cost techniques for estimating the chemical constituents of fugitive dust from an eroding
field. From chemical analyses of actively eroding sediments, it would appear that Ca is the only chemical species that is
enriched more than others during the process of fugitive dust production. We found surface soil sieved to produce a sub-sample
with particle diameters in the range of 53–74 μm to be a reasonably good surrogate for fugitive dust very near the source
field, that sieved sub-samples with particle diameters <10 μm have a crustal enrichment factor of approximately 6, and that
this factor, multiplied by the chemical contents of source soils, may be a reasonable estimator of fugitive PM10 chemistry from the soils of interest. We also found that dust from tractor air cleaners provided a good surrogate for dust
entrained by tillage and harvesting operations if the chemical species resulting from engine wear and exhaust were removed
from the data set or scaled back to the average of enrichment factors noted for chemical species with no known anthropogenic
sources. Chemical analyses of dust samples collected from attics approximately 4 km from the nearest source fields indicated
that anthropogenic sources of several environmentally important nutrient and trace element species are much larger contributors,
by up to nearly two orders of magnitude, to atmospheric loading and subsequent deposition than fugitive dust from eroding
soils. 相似文献
19.
Febros river water was sampled weekly, during 35 successive weeks, and analyzed for microbiological (total coliforms, faecal
coliforms, faecal streptococci and enterococci) and chemical-physical (ammonia and temperature) parameters. All microbiological
parameters were highly correlated with each other and with ammonia, suggesting that the simultaneous determination of all
variables currently in use in the evaluation of the microbiological quality of waters is probably redundant, and could be
simplified, and that ammonia should be tested as a sentinel parameter of the microbiological pollution load of Febros river.
From the strains isolated from positive tubes of the faecal coliforms test (multiple tube fermentation technique) and retested
in this assay, Escherichia coli, Klebsiella oxytoca and Klebsiella pneumoniae subsp. pneumoniae strains were positive, indicating that the faecal coliforms test is not totally specific for Escherichia coli, and can detect other bacteria. Considering that these Klebsiella spp. are not necessarily of faecal origin, it was concluded that the faecal coliforms test can overestimate true faecal pollution.
From the strains isolated from positive tubes of the faecal coliforms procedure, only Escherichia coli strains were clearly positive in the β-D-glucuronidase test. All other species were negative or very weakly positive, suggesting that the assay of the β-D-glucuronidase activity is less prone to false positives than the faecal coliforms test in the quantification of Escherichia coli in environmental waters. 相似文献
20.
The study was aimed at determining the levels of metals in water samples and muscles of the fish caught in the Una River basin,
located in the northwestern part of Bosnia and Herzegovina. For that purpose, three fish species: Brown Trout (Salmo trutta m. fario), Grayling (Thymallus thymallus) and Californian Trout (Salmo gairdneri), together with stem water samples, were analyzed for metal concentrations (Pb, Hg, Cd, As, Mn, Ni, Cu, Cr, Se, Co, Sn, Zn,
Fe, Ca, P) during a 2-year period. The fish was captured using electric fishing, nets or fishing equipment. The capture was
undertaken on three sites (the river source, the middle flow and the river mouth) of each of the five biggest rivers belonging
to the Una River basin (Unac, Krušnica, Sana, Klokot, and Una). The concentrations of metals in each sample were determined
via atomic absorption spectrophotometry. In the tested waters, the presence of Mn in concentrations higher than permitted
(0.07 mg/l) had been detected. In the tested meat, the following average concentrations of metals (mg/kg) had been found:
Pb (0.67), Cd (0.06), Mn (0.65), Ni (0.15), Cu (0.79), Cr (1.05), Se (0.03), Zn (8.92), Fe (5.40), Ca (14.68), and P (10.85).
The correlation between Mn concentrations identified in the tested waters and those identified in the meat of Brown Trout
was revealed to be statistically significant, which confirms that, over time, bioaccumulation of metals took place. Even though
the results were not indicative of contamination, they strongly suggest that constant monitoring of the ecosystems in reference
should be implemented. 相似文献