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101.
Monitoring of immission of persistent organic pollutants in the industrialized area of Volta Redonda (V.R.) and in the National Park of Itatiaia (PNI) in southeast Brazil was performed using an endemic bromeliad species as biomonitor and measuring bulk deposition rates of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH). For the sum of PCB, overall deposition rates were between 17 and 314 ng/(m2 day) in winter and between 43 and 81 ng/(m2 day) in summer, respectively. Deposition rates of dioxin-like PCBs ranged from 0.14 to 2.8 pg WHO-TEQ/(m2 day) in winter and from 0.90 to 4.3 pg WHO-TEQ/(m2 day) in summer. PCB deposition rates (total PCB and WHO-TEQ) were in the same range in winter in V.R. and PNI. In summer, contamination levels in V.R. were 6-10-folds higher than in PNI. PCB concentrations in biomonitor samples from V.R. and PNI were in the same range in summer and in winter. Concentrations of total PCB ranged from 14 to 95 microg/kg dry matter (d.m.) in winter and from 18 to 27 microg/kg d.m. in summer, respectively. The TEQ values were between 1.7 and 4.1 ng WHO-TEQ/kg d.m. in winter and between 1.9 and 2.9 ng WHO-TEQ/kg d.m. in summer. PCB concentrations of di-ortho PCB but not of non-ortho PCB were a factor of 2-4 lower in summer in both areas. PCB congener profiles resembled those from technical formulations. The profiles shifted to the higher chlorinated congeners in summer, probable due to revolatilisation of the lighter components at higher temperatures. PCB profiles in biomonitor resembled those from deposition samples and the shift to the heavier congeners in summer was even more pronounced. PAH deposition rates were in a similar range in both areas (131-2415 ng/(m2 day)). PAH levels in biomonitor samples from V.R. were about one order of magnitude higher than in samples from PNI indicating the impact of local sources. PAH profiles revealed stationary thermal processes as main source of contamination in V.R. whereas in PNI, biomass burning seems to be the main contamination source.  相似文献   
102.
During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown São Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as well as major ions (Na+, $ \rm NH^{ + }_{4} During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown S?o Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as well as major ions (Na+, , K+, Ca2+, Mg2+, Cl, , ) and carboxylic acids (acetic, formic and oxalic) using ion chromatography. The volume weighted mean, VWM, of the anions , and Cl was, respectively, 20.3, 12.1 and 10.7 μmol l−1. Rainwater in S?o Paulo was acidic, with 55% of the samples exhibiting a pH below 5.6. The VWM of the free H+ was 6.27 μmol l−1), corresponding to a pH of 5.20. Ammonia (NH3), determined as (VWM = 32.8 μmol l−1), was the main acidity neutralizing agent. Considering that the H+ ion is the only counter ion produced from the non-sea-salt fraction of the dissociated anions, the contribution of each anion to the free acidity potential has the following profile: (31.1%), (26.0%), CH3COO (22.0%), Cl (13.7%), HCOO (5.4%) and (1.8%). The precipitation chemistry showed seasonal differences, with higher concentrations of ammonium and calcium during autumn and winter (dry period). The marine contribution was not significant, while the direct vehicular emission showed to be relevant in the ionic composition of precipitation.  相似文献   
103.
Environmental Science and Pollution Research - The fate of pharmaceuticals during the treatment of effluents is of major concern since they are not completely degraded and because of their...  相似文献   
104.
Soil respiration rates of a clay-loam textured Acrisol under different uses (Atlantic forest, manioc, horticulture and pasture) from Rio de Janeiro State were measured. The relationship between carbon dioxide (CO2) emissions and soil physico-chemical properties were investigated. Rates of CO2 emission of two sites (Atlantic forest and horticulture) were also evaluated in different seasons in 1997 and 1998. In the forest site, monthly means of measured respiration rates showed good correlation with soil temperature in the range 19.6–24.1°C (r2 = 0.89). In the horticulture site, no change was observed with soil moisture alone, in the range 3.0–13.2 wt%. In the horticulture soil, even when the surface soil was very dry, respiration rates increased in the hot, wetter summer but remained higher than the mean flux from forest soil. The CO2 emission flux of the Acrisol under different use showed good correlation with soil temperature (r2 = 0.72) and moisture (r2 = 0.61).  相似文献   
105.
Juvenile sea bass, Dicentrarchus labrax L., were exposed during 2, 4, 8, and 24 h to 0.9 microM beta-naphthoflavone (BNF), 131 nM 17 beta-estradiol (E(2)), 4.05 microM 4-nonylphenol (NP), as well as to BNF combined either to E(2) or NP (maintaining the previous concentrations). Liver cytochrome P450 content (P450), ethoxyresorufin-O-deethylase (EROD), and glutathione S-transferase (GST) activities were measured in order to evaluate biotransformation responses. Genotoxicity was assessed as erythrocytic nuclear abnormalities (ENA) frequency. The effects on endocrine function were evaluated as plasma cortisol and glucose. Cortisol was not affected by xeno/estrogens tested, either in single exposure or mixed with BNF. Nevertheless, the intermediary metabolism was affected since glucose concentration increased after 4 h exposure to E(2), and after all BNF+NP exposure lengths. Moreover, a synergism between BNF and NP was thoroughly demonstrated, whereas a sporadic antagonistic interaction was found at 4 h BNF + E(2) exposure. Liver EROD and GST activities were not significantly altered by single E(2) or NP exposure. However, both compounds were able to induce EROD activity in the presence of BNF. NP single exposure was able to significantly increase liver P450 content, while its mixture with BNF displayed an antagonistic interference. Considering the xeno/estrogens single exposures, only NP induced an ENA increase; however, both mixtures (BNF + E(2) and BNF + NP) displayed genotoxic effects. Fish responses to mixtures of xenobiotics are complex and the type of interaction (synergism/potentiation or antagonism) in a particular mixture can vary with the evaluated biological response.  相似文献   
106.
This article describes the assessment of possible allelopathic potential of organic extracts obtained from leaves of Canavalia ensiformis under laboratory conditions. Furthermore, a systematic evaluation of these extracts was carried out using specific protocols developed in capillary electrophoresis (CE) to determine some groups of secondary metabolites. After the identification and quantification of compounds, the effects of compounds on germination of some common weeds was investigated, which are becoming a real problem in pastures in the state of Pará, Brazil.  相似文献   
107.
This paper presents a method of investigating the distributional pattern of a biological population, using a technique of simulation. The method consists of the comparison of the empirical frequency curve of a population, obtained using the Method of Quadrats, with a simulated one, since the pattern of the simulated curve depends on the simulated distribution. An example is given.  相似文献   
108.
Distribution and feeding in the onuphid polychaete,Diopatra cuprea (Bosc)   总被引:1,自引:0,他引:1  
Population density of the onuphid polychaete Diopatra cuprea is poorly correlated with particle size distribution of the substratum. It varies directly, however, with current velocity. Measurements of the volume of oxygen drawn through the tube by the inhabitants' rhythmic activities, and the volume consumed under similar conditions, indicate that the rate of oxygen utilization is unusually low; therefore, the influence of current velocity cannot be exerted through its effect on oxygen supply. We suggest that the worm's tube, which protrudes several centimeters above the substratum in the form of an inverted hook, is a food-catching device whose efficiency is governed by the volume of water flowing past. This hypothesis is supported by the identity of many species found both in the gut and on the tube. We also suggest that the tube-irrigating activities permit the animal to test the medium for the presence of chemical stimuli emanating from food caught by the tube; supra-threshold concentrations of these stimuli elicit the feeding response.  相似文献   
109.
Food and Environmental Virology - The availability of drinking water is one of the main determinants of quality of life, disease prevention and the promotion of health. Viruses are important agents...  相似文献   
110.
The aim of this study was to investigate hepatitis A virus (HAV), hepatitis E (HEV), and rotavirus (RV) in fresh and processed meat traded on the border of Brazil with Argentina and Uruguay. In total, 159 samples of raw and processed foods of animal origin were collected in Paso de los Libres, Argentina (n?=?53 raw meat, n?=?24 processed meat) and Rivera, Uruguay (n?=?55 raw meat, n?=?18 processed meat), or were seized by the Brazilian International Agricultural Surveillance System—VIGIAGRO (Brazil–Argentina border) (n?=?8 raw meat, n?=?1 bush meat). All samples were tested for the presence of HAV, HEV, and RV genomes. HAV genes were detected in 18.23% of samples and RV genes in 23.89%. No HEV-positive samples were detected. HAV was also detected in two of the VIGIAGRO samples. Processed meats from Argentina and Uruguay had a higher rate of HAV and RV than raw meat (P?>?0.05). The median HAV in the Argentinian and Uruguayan samples was 6.9?×?104 and 3.5?×?103 copies/g, respectively. The presence of RV viral genes in raw meats from Argentina was significant, and this was not observed in processed meats. The presence of HAV and RV genes in a significant portion of products from Argentina and Uruguay is a potential source of human infection. This also indicates precarious conditions of acquisition, processing, and manipulation, which could be improved by improved regulation of food across borders.  相似文献   
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