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211.
Seasonal Fluctuation in Heavy Metal Pollution in Iran´s Siahroud River - A Preliminary Study (7 pp) 总被引:1,自引:0,他引:1
Charkhabi AH Sakizadeh M Rafiee G 《Environmental science and pollution research international》2005,12(5):264-270
Background The management of its available water resources has become a key issue for Iran. During the last few decades, the water quality
of Siahroud River in the coastal plain of the Caspian Sea in Gilan Province in Northern Iran has significantly degraded. The
scarcity of water has been compounded by rapid population growth and increasing pollution from fertilizers, pesticides, and
municipal and industrial wastes. One of the sources of this degradation is the movement of heavy metals from the river's watershed
into the various water systems supported by the river, including the water system for Rasht City.
Methods To study the magnitude of heavy metal pollution in the Siahroud River, seven heavy metals including Zn, Cu, Pb, Cd, Mn, Fe,
and Ni were measured in duplicate from replicated water samples collected over five consecutive seasons and analyzed by Atomic
Absorption Spectrometry. In situ measurements of pH were taken with the samples and total organic carbon (TOC) was analyzed
by IR gas measurement.
Results The results demonstrated that four of the seven heavy metals including Pb, Fe, Cd, and Mn exceeded permissible safe levels
as established by the United States Environmental Protection Agency. Multivariate factor analysis suggested that industrial
land-use was the main contributing factor for the high levels of Fe and Mn in the Siahroud River, whereas, Cd was principly
from agricultural activities in the watershed. The data also suggested that pH and TOC had an important role in the behaviour
of Pb and Mn, and that the elevated levels of these two heavy metals in Siahroud River was the consequence of other anthropogenic
sources. Only negligible levels of Zn, Cu and Ni were detected. Finally, all the sampling stations were subjected to cluster
analysis. The results indicated that three different zones could be distinguished according to the levels of pollution. In
addition, it was shown that the urban areas did not have a significant impact on the heavy metal pollution in the river. This
observation stems from the fact that the data from the sampling stations before and after Rasht City were not significantly
different.
Recommendation . Preventive measures need to be undertaken in the land-use systems and watersheds of the Siahroud River to reduce the pollution
levels of Pb, Cd, Mn and Fe. 相似文献
212.
López-Ovejero RF y Garcia AG de Carvalho SJ Christoffoleti PJ Neto DD Martins F Nicolai M 《Journal of environmental science and health. Part. B》2005,40(1):1-11
Brazilian off-season maize production is characterized by low yield due to several factors, such as climate variability and inadequate management practices, specifically weed management. Thus, the goal of this study was to determinate the critical period of weed competition in off-season maize (Zea mays L.) crop using thermal units or growing degree days (GDD) approach to characterize crop growth and development. The study was carried out in experimental area of the University of S?o Paulo, Brazil, with weed control (C), as well as seven coexistence periods, 2, 4, 6, 8, and 12 leaves, flowering, and all crop cycle; fourteen treatments were done. Climate data were obtained from a weather station located close to the experimental area. To determine the critical period for weed control (CPWC) logistic models were fitted to yield data obtained in both W and C, as a function of GDD. For an arbitrary maximum yield loss fixed in 2.5%, the CPWC was found between 301 and 484 GDD (7-8 leaves). Also, when the arbitrary loss yield was fixed in 5 and 10%, the period before interference (PBI) was higher than the critical weed-free period (CWFP), suggesting that the weeds control can be done with only one application, between 144 and 410 GDD and 131 and 444 GDD (3-8 leaves), respectively. The GDD approach to characterize crop growth and development was successfully used to determine the critical period of weeds control in maize sown off-season. Further works will be necessary to better characterize the interaction and complexity of maize sown off-season with weeds. However, these results are encouraging because the possibility of the results to be extrapolated and because the potential of the method on providing important results to researchers, specifically crop modelers. 相似文献
213.
The aim of this study was to determine the efficacy of selected basidiomycetes in the removing of polycyclic aromatic hydrocarbons (PAH) from the creosote-contaminated soil. Fungi Pleurotus ostreatus and Irpex lacteus were supplemented with creosote-contaminated (50-200 mg kg(-1) PAH) soil originating from a wood-preserving plant and incubated at 15 °C for 120 d. Either fungus degraded PAH with 4-6 aromatic rings more efficiently than the microbial community present initially in the soil. PAH removal was higher in P. ostreatus treatments (55-67%) than in I. lacteus treatments (27-36%) in general. P. ostreatus (respectively, I. lacteus) removed 86-96% (47-59%) of 2-rings PAH, 63-72% (33-45%) of 3-rings PAH, 32-49% (9-14%) of 4-rings PAH and 31-38% (11-13%) of 5-6-rings PAH. MIS (Microbial Identification System) Sherlock analysis of the bacterial community determined the presence of dominant Gram-negative bacteria (G-) Pseudomonas in the inoculated soil before the application of fungi. Complex soil microbial community was characterized by phospholipid fatty acids analysis followed by GC-MS/MS. Either fungus induced the decrease of bacterial biomass (G- bacteria in particular), but the soil microbial community was influenced by P. ostreatus in a different way than by I. lacteus. The bacterial community was stressed more by the presence of I. lacteus than P. ostreatus (as proved by the ratio of the fungal/bacterial markers and by the ratio of trans/cis mono-unsaturated fatty acids). Moreover, P. ostreatus stimulated the growth of Gram-positive bacteria (G+), especially actinobacteria and these results indicate the potential of the positive synergistic interaction of this fungus and actinobacteria in creosote biodegradation. 相似文献
214.
We report observations of disappearance of Erica tetralix in wet heathland, which is unlikely to be caused by competition, as E. tetralix is dying before its place is taken up by other species. To investigate the causes, we used both old and new data. Results showed that presence of Molinia caerulea and Calluna vulgaris were substantial in the former E. tetralix dominated areas. Measurements of the C/N ratio in the morlayer were between 21 and 26 under the E. tetralix stands. As the expected C/N ratio in a healthy nutrient poor ecosystem like the E. tetralix wet heathland is around 30, this indicates that the ratio is probably decreasing and, correspondingly, the probability of nitrogen leaching from the ecosystem is increasing. The morlayer pH was extremely low—between 3.03 and 3.78. This represents a pH decline since the 1960s, where pH values generally were above 4. This supports the hypothesis that the decrease in morlayer pH is the major factor explaining the disappearance of E. tetralix and that measures to increase pH should be considered as part of the recommendations for relevant future management.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-012-0251-z) contains supplementary material, which is available to authorized users. 相似文献215.
Minh TB Watanabe M Tanabe S Miyazaki N Jefferson TA Prudente MS Subramanian A Karuppiah S 《Environmental pollution (Barking, Essex : 1987)》2000,110(3):735-468
For understanding global distribution, transport and behavior of tris(4-chlorophenyl)methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH), the two newly identified microcontaminants, the present study determined their concentrations and other persistent organochlorines (OCs) in the blubber of nine species of adult male cetaceans collected from various locations in the North Pacific Ocean and coastal waters of some Asian countries, during 1985-97. Concentrations of TCPMe and TCPMOH were found to be highest in northern right whale dolphins, which may be attributable to wide distribution of this species, including some heavily polluted areas such as coastal California. Elevated residue levels of TCPMe and TCPMOH were observed in both off-shore and coastal species, suggesting widespread contamination of these compounds in the marine environment. Higher contamination of TCPMe and TCPMOH was found in cetaceans from temperate and cold waters than those from tropical regions. The latitudinal distribution of TCPMe and TCPMOH in cetaceans from the North Pacific and Asian coastal waters was similar to that of DDTs, suggesting less transportable nature of TCPMe and TCPMOH in the marine environment. Data on the occurrence of TCPMe and TCPMOH further indicated high bioaccumulation potential of these compounds, which was comparable to DDTs. Relative concentrations of TCPMe/TCPMOH in cetaceans were apparently higher than those observed in seals, suggestive of lower metabolic capacity for these compounds in cetaceans than in pinnipeds, which is similar to classic contaminants like polychlorinated biphenyls and DDTs. 相似文献
216.
Fuerhacker M Bauer H Ellinger R Sree U Schmid H Zibuschka F Puxbaum H 《Chemosphere》2001,44(5):1213-1221
Nitric oxide (NO) is an intermediate of denitrification process and can be produced by denitrifiers, nitrifiers and other bacteria. In our experiments we measured the dynamic flow of NO depending on oxidation reduction potential (ORP). Different ORP-ranges were related to various carbon loading stages in the wastewater treatment pilot plant. Nitrification and denitrification were achieved by a sequence of aeration and non-aeration periods. Our measurements show that different carbon loading conditions (low feed, balanced and overloaded conditions) did not change the range of the mixing ratio of NO emissions when the aeration conditions like air-flow and temperature were kept constant. Minimum and maximum NO mixing ratios were 34.7 and 91.8 ppbv; 52.3 and 91.3 ppbv; 57.6 and 109 ppbv for low feed, balanced and overloaded conditions, respectively. The curve of the NO graph relied on nitrification/denitrification dynamics. The dependence of NO release on different ORP and CO2-release during the various conditions are shown. Longer aeration times resulted in an increased release of gaseous NO. The net-release of NO g(-1) nitrogen removed was between 0.014% and 0.028%. The NO fluxes to the air were observed between 8.3 and 14.9 mg m(-2) d(-1) NO. The major release occurred during high aeration periods whereas the concentration of dissolved [NOaq] in the wastewater was less than 0.05% of the gaseous release due to very low solubility of the NO. 相似文献
217.
Debellefontaine H Chakchouk M Foussard JN Tissot D Striolo P 《Environmental pollution (Barking, Essex : 1987)》1996,92(2):155-164
There is growing concern about the problems of waste elimination. We should consider our environment as being borrowed from future generations and refrain from leaving a legacy of problems we are not able to solve. Various oxidation techniques are suited for the elimination of organic aqueous wastes, but because of the environmental drawbacks of incineration, enclosed processes, like liquid phase oxidation should be preferred. Wet air oxidation (WAO) under high temperature (200-325 degrees C) and pressure (50-150 bar) is suited to such liquid wastes and various catalysts, including hydrogen peroxide, can be used in order to increase the efficiency without increasing temperature and pressure. Wet Peroxide Oxidation (WPO) is a similar process. A comparable oxidation efficiency is obtained when using hydrogen peroxide as the oxidising agent instead of oxygen, at a temperature of only 100-120 degrees C. As opposed to WAO, which is capital intensive, WPO needs limited capital but generates higher running costs. The paper reviews the major results obtained for both processes and assesses the field of possible application of each of them. TOC removal efficiencies typically obtained range from 65 to 90% or more for most of the pollutants. 相似文献
218.
Changes in concentration of five PCDD/F congeners after cooking beef from treated cattle 总被引:3,自引:0,他引:3
A large piece of meat taken from a single animal, which had been dosed with five selected PCDD/Fs, was prepared and cooked by a selection of different methods; burgers (fried, grilled, barbecued), roasts (cooked using conventional and microwave ovens) and stews (open pan and pressure cooked). For some of the cooking methods, concentration changes, on a whole product basis, were observed between raw and cooked product. However, in all cases these could be explained simply through changes arising from loss of water and elimination of PCDD/Fs with released fat. The total amounts of PCDD/Fs present in the system (including in released fat) remained unchanged. Dietary intake of PCDD/Fs could therefore be reduced by the removal of visible fat from meat before cooking and by discarding any fat released from foods during the cooking process. 相似文献
219.
Wada M Kido H Kishikawa N Tou T Tanaka M Tsubokura J Shironita M Matsui M Kuroda N Nakashima K 《Environmental pollution (Barking, Essex : 1987)》2001,115(1):139-147
Air pollutants such as polycyclic aromatic hydrocarbons (PAHs), their nitrated derivatives (NPAHs), and some metals on airborne particles in Nagasaki city, Japan were determined over a period of 12 months by high-performance liquid chromatography with chemiluminescence, fluorescence and flameless atomic absorption spectrometry. The average concentrations (range) were 18.24 (4.07-41.54) ng/m3 for total PAHs, 0.91 (0.23-4.10) pg/m3 for NPAHs, 7.95 (1.71-16.31) ng/m3 for Pb, 11.56 (3.35-24.96) ng/m3 for Mn and 3.79 (0.97-14.71) ng/m3 for Ni (n = 136). The toxic equivalency factors adjusted concentration of total PAHs determined in Nagasaki city area was 2.33 ng/m3. Concentrations of total PAHs and NPAHs in winter were higher than those in summer. In a weekly variations study, total PAHs and NPAHs concentrations, as well as traffic volume showed a similar tendency with all values higher during weekdays and lower at the weekend. The correlation coefficients between total PAHs or NPAHs and traffic volume were 0.781 and 0.818, respectively. These results suggested that one of the main sources for NPAHs and PAHs in a city area might be motor vehicles. 相似文献
220.
Steubing L Fangmeier A Both R Frankenfeld M 《Environmental pollution (Barking, Essex : 1987)》1989,58(4):281-302
The native ground vegetation of a beech forest was fumigated with moderate doses of SO(2), NO(2), and O(3) in open-top chambers. The effects of fumigants on growth and above-ground development were dependent on species. The treatments caused early senescence in several of the species present. The epicuticular waxes were attacked by fumigation, which was shown by higher wettability of the leaf surfaces and by leaching of ions. Interspecific differences were observed in the responses of transpiration and photosynthesis to fumigation. Similar patterns of effects on transpiration and photosynthesis, however, were found in the same species. Carbohydrate metabolism was altered by fumigation, leading to starch accumulation in the leaves. Besides effects on higher plants, fumigations also resulted in alterations of the soil microflora. The bacteria/fungi ratio was depressed at the fumigation plots. 相似文献