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41.
N. P. Kosykh N. P. Mironycheva-Tokareva A. M. Peregon E. K. Parshina 《Russian Journal of Ecology》2008,39(7):466-474
New experimental data on biological productivity of plant communities in oligotrophic and mesotrophic bogs of the middle taiga
subzone over the past five years are presented. The relationship between net primary production and the stock of live phytomass
is estimated. The stock of necromass in oligotrophic bog ecosystems increases from west to east, while the stock of live phytomass
and net primary production decrease. 相似文献
42.
P.P. Povinec H. Bokuniewicz W.C. Burnett J. Cable M. Charette J.-F. Comanducci E.A. Kontar W.S. Moore J.A. Oberdorfer J. de Oliveira R. Peterson T. Stieglitz M. Taniguchi 《Journal of environmental radioactivity》2008,99(10):1596
Results of groundwater and seawater analyses for radioactive (3H, 222Rn, 223Ra, 224Ra, 226Ra, and 228Ra) and stable (D and 18O) isotopes are presented together with in situ spatial mapping and time series 222Rn measurements in seawater, direct seepage measurements using manual and automated seepage meters, pore water investigations using different tracers and piezometric techniques, and geoelectric surveys probing the coast. This study represents first time that such a new complex arsenal of radioactive and non-radioactive tracer techniques and geophysical methods have been used for simultaneous submarine groundwater discharge (SGD) investigations. Large fluctuations of SGD fluxes were observed at sites situated only a few meters apart (from 0 cm d−1 to 360 cm d−1; the unit represents cm3/cm2/day), as well as during a few hours (from 0 cm d−1 to 110 cm d−1), strongly depending on the tidal fluctuations. The average SGD flux estimated from continuous 222Rn measurements is 17 ± 10 cm d−1. Integrated coastal SGD flux estimated for the Ubatuba coast using radium isotopes is about 7 × 103 m3 d−1 per km of the coast. The isotopic composition (δD and δ18O) of submarine waters was characterised by significant variability and heavy isotope enrichment, indicating that the contribution of groundwater in submarine waters varied from a small percentage to 20%. However, this contribution with increasing offshore distance became negligible. Automated seepage meters and time series measurements of 222Rn activity concentration showed a negative correlation between the SGD rates and tidal stage. This is likely caused by sea level changes as tidal effects induce variations of hydraulic gradients. The geoelectric probing and piezometric measurements contributed to better understanding of the spatial distribution of different water masses present along the coast. The radium isotope data showed scattered distributions with offshore distance, which imply that seawater in a complex coast with many small bays and islands was influenced by local currents and groundwater/seawater mixing. This has also been confirmed by a relatively short residence time of 1–2 weeks for water within 25 km offshore, as obtained by short-lived radium isotopes. The irregular distribution of SGD seen at Ubatuba is a characteristic of fractured rock aquifers, fed by coastal groundwater and recirculated seawater with small admixtures of groundwater, which is of potential environmental concern and has implications on the management of freshwater resources in the region. 相似文献
43.
Kalbande DM Dhadse SN Chaudhari PR Wate SR 《Environmental monitoring and assessment》2008,138(1-3):233-238
Abstract Industrial development and consumption of petroleum products leads to increase air pollution levels especially in
urban and industrial areas. Heavy metal components associated with air pollutants have far reaching effects with respect to
economic and ecological importance of pollens. The pollens are male reproductive organs of the plant and travel through air
from flower to flower for pollination purpose. During this period they are exposed to air pollutants. Present investigation
thus pertains to study of effect of air pollutants on pollens especially biosorption and bioaccumulation of heavy metals.
The pollens of three commonly occurring plants namely Cassia siamea, Cyperus rotundus, Kigelia pinnata have been studied from the NH-6 of Nagpur city, India. The pollens exposed to polluted air showed the presence of higher
concentrations of Ca, Al and Fe as compared to unexposed pollens. Higher concentration of these metals was observed in Cyperus rotundus followed by Cassia siamea and Kigelia pinnata. These results indicate that pollens act as good indicator of air pollution giving results in short time of exposure of 5–10 h.
Apart from this, it is also reported that some of these metals play crucial role in the metabolic activity in pollens for
example Calcium is necessary for growth of pollen tube and other metabolic activities in pollens. The presence of these metals
in pollens may also enhance the allergenicity of the pollens. Similarly accumulation of heavy metals may also deteriorate
the quality of pollen for their economical use. The viability of pollen is also affected by these pollutants in sensitive
species leading to impairment of their fertility. 相似文献
44.
Clausen L Arildskov NP Larsen F Aamand J Albrechtsen HJ 《Journal of contaminant hydrology》2007,89(3-4):157-173
The worldwide used herbicide dichlobenil (2,6-dichlorobenzonitrile) has resulted in widespread presence of its metabolite 2,6-dichlorobenzamide (BAM) in surface water and groundwater. To evaluate the potential for natural attenuation of this BAM pollution in groundwater, we studied the degradation of BAM and dichlobenil in 16 samples of clayey till, unconsolidated sand and limestone, including sediments from both oxidized and reduced conditions. The degradation of dichlobenil occurred primarily in the upper few meters below surface, although dichlobenil was strongly sorbed to these sediments. However, the degradation of dichlobenil to BAM could not be correlated to either sorption, water chemistry, composition of soils or sediments. Degradation of dichlobenil to BAM was limited (<2% degraded) in the deeper unsaturated zones, and no degradation was observed in aquifer sediments. This illustrates, that dichlobenil transported to aquifers does not contribute to the BAM-contamination in aquifers. A small, but significant degradation of BAM was observed in the upper part of the unsaturated zones in sandy sediments, but no degradation was observed in the clayey till sediment or in the deeper unsaturated zones. The insignificant degradation of BAM in aquifer systems shows that BAM pollution detected in aquifers will appear for a long time; and consequently the potential for natural attenuation of BAM in aquifer systems is limited. 相似文献
45.
Adamo P Crisafulli P Giordano S Minganti V Modenesi P Monaci F Pittao E Tretiach M Bargagli R 《Environmental pollution (Barking, Essex : 1987)》2007,146(2):392-399
Lobes of the lichen Pseudevernia furfuracea (L.) Zopf and shoots of the moss Hypnum cupressiforme Hedw. were subjected to different treatments (water washing, oven drying, HNO3 washing, NH4-oxalate extraction) to assess the influence of vitality on accumulation efficiency, during a 6-week exposure in bags in two Italian cities, Trieste and Naples. No trend emerged between treatments, in terms of accumulation ability, for major and trace elements. Only water-washed lichens showed an increased C and N content after exposure in both cities. Element concentrations generally reached higher values in mosses than in lichens, especially for Al, Fe, and Zn (both cities), and for Cu, Mg and Na (Naples). Surface development strongly influenced accumulation capacity of the biomonitors. Quartzose and cation exchange filters revealed, on a weight basis, a poor performance. In urban environments, surface interception of atmospheric particulate seems to play a major role in accumulation, irrespective of organism vitality. 相似文献
46.
Bhattacharyya P Chakrabarti K Chakraborty A Nayak DC Tripathy S Powell MA 《Chemosphere》2007,66(9):1789-1793
The importance of the use of potassium in agriculture is increasing in South Asia for making most productive use of the nutrient in terms of economic returns. Nutrient supply traditionally by cattle manure is constrained by its insufficient availability. Municipal waste compost may be an alternative source of nutrient supplements. Field experiments were conducted at the Experimental Farm of Calcutta University, West Bengal, India during the wet seasons of 1997, 1998 and 1999 on flooded lowland rice. Potassium fractions in municipal waste compost and cattle manure were determined by sequential extraction and also the potassium uptake by rice to compare the effectiveness of municipal waste compost with traditional manure. Potassium was significantly bound to the organic matter in municipal waste compost. Potassium uptake by rice grain and straw increased significantly with the combined application of organics and fertilizers and it was higher in grain than in straw. Water-soluble and non-exchangeable potassium contents of municipal waste compost and cattle manure were highly correlated with the uptake of potassium by straw and grain. Exchangeable and residual potassium were also significantly correlated with the uptake of potassium by straw and grain of rice. Much higher uptake of K in rice straw and rain resulted from applying the manures in conjunction with fertilizers than when applied singly. 相似文献
47.
The sonochemical degradation of the systematically substituted azo compound 2,7-dihydroxy-1-phenylazonaphthaline-3,6-disulfonic acid was investigated using a frequency of 850 kHz and an acoustic input power of 61 W. All derivatives were degraded completely within 6h by the ultrasonic treatment. Trifluoromethyl substituted azo compounds exhibited 2-3-fold higher degradation rates in comparison to the reference hydrogen substituted azo compound (k=0.54 h(-1)). In contrast to enzymatic processes (azoreductase or laccase), the ultrasonic treatment for these ortho-, meta-, and para-substituted azo compound showed 1.5-50-fold higher degradation rates. Additionally the ultrasound treatment was characterized by shorter reaction times. As a result of the detection and identification of specific intermediates using LC-MS a reaction pathway of the sonochemical degradation of the analysed azo compound is proposed indicating the formation of cyclohexadienone and naphthalene quinone derivatives. 相似文献
48.
Determinants of Farmers’ Adoption of Improved Soil Conservation Technology in a Middle Mountain Watershed of Central Nepal 总被引:2,自引:0,他引:2
This study explores different socio-economic and institutional factors influencing the adoption of improved soil conservation technology (ISCT) on Bari land (Rainfed outward sloping terraces) in the Middle Mountain region of Central Nepal. Structured questionnaire survey and focus group discussion methods were applied to collect the necessary information from farm households. The logistic regression model predicted seven factors influencing the adoption of improved soil conservation technology in the study area including years of schooling of the household head, caste of the respondent, land holding size of the Bari land, cash crop vegetable farming, family member occupation in off farm sector, membership of the Conservation and Development Groups, and use of credit. The study showed that technology dissemination through multi-sectoral type community based local groups is a good option to enhance the adoption of improved soil conservation technology in the Middle Mountain farming systems in Nepal. Planners and policy makers should formulate appropriate policies and programs considering the farmers' interest, capacity, and limitation in promoting improved soil conservation technology for greater acceptance and adoption by the farmers. 相似文献
49.
Rutter AP Schauer JJ Lough GC Snyder DC Kolb CJ Von Klooster S Rudolf T Manolopoulos H Olson ML 《Journal of environmental monitoring : JEM》2008,10(1):102-108
Gaseous elemental mercury (GEM), particulate mercury (PHg) and reactive gaseous mercury (RGM) were measured every other hour at a rural location in south central Wisconsin (Devil's Lake State Park, WI, USA) between April 2003 and March 2004, and at a predominantly downwind urban site in southeastern Wisconsin (Milwaukee, WI, USA) between June 2004 and May 2005. Annual averages of GEM, PHg, and RGM at the urban site were statistically higher than those measured at the rural site. Pollution roses of GEM and reactive mercury (RM; sum of PHg and RGM) at the rural and urban sites revealed the influences of point source emissions in surrounding counties that were consistent with the US EPA 1999 National Emission Inventory and the 2003-2005 US EPA Toxics Release Inventory. Source-receptor relationships at both sites were studied by quantifying the impacts of point sources on mercury concentrations. Time series of GEM, PHg, and RGM concentrations were sorted into two categories; time periods dominated by impacts from point sources, and time periods dominated by mercury from non-point sources. The analysis revealed average point source contributions to GEM, PHg, and RGM concentration measurements to be significant over the year long studies. At the rural site, contributions to annual average concentrations were: GEM (2%; 0.04 ng m(-3)); and, RM (48%; 5.7 pg m(-3)). At the urban site, contributions to annual average concentrations were: GEM (33%; 0.81 ng m(-3)); and, RM (64%; 13.8 pg m(-3)). 相似文献
50.
A microplate method was developed as a tool to test phages for their ability to control Salmonella in aqueous environments. The method used EPA (U.S. Environmental Protection Agency) worst case water (WCW) in 96-well plates. The WCW provided a consistent and relatively simple defined turbid aqueous matrix, high in total organic carbon (TOC) and total dissolved salts (TDS), to simulate swine lagoon effluent, without the inconvenience of malodor and confounding effects from other biological factors. The WCW was originally defined to simulate high turbidity and organic matter in water for testing point-of-use filtration devices. Use of WCW to simulate lagoon effluent for phage testing is a new and innovative application of this matrix. Control of physical and chemical parameters (TOC, TDS, turbidity, temperature, and pH) allowed precise evaluation of microbiological parameters (Salmonella and phages). In a typical application, wells containing WCW were loaded with Salmonella enterica susp. enterica serovar Typhimurium (ATCC14028) and treated with phages alone and in cocktail combinations. Mean Salmonella inactivation rates (k, where the lower the value, the greater the inactivation) of phage treatments ranged from -0.32 to -1.60 versus -0.004 for Salmonella controls. Mean log(10) reductions (the lower the value, the greater the reduction) of Salmonella phage treatments were -1.60 for phage PR04-1, -2.14 for phage PR37-96, and -2.14 for both phages in a sequential cocktail, versus -0.08 for Salmonella controls. The WCW microcosm system was an effective tool for evaluating the biocontrol potential of Salmonella phages. 相似文献