A new method for spectrophotometric determination of benzene in air

A new spectrophotometric method for the determination of benzene in air is described. The method is based upon the nitration of benzene to m-dinitrobenzene and subsequent reduction to m-phenylenediamine. m-Phenylenediamine is determined by diazotization-coupling reaction. α-Naphthol is used as a coupling reagent. Beer's law is obeyed in the range of 10–80 μg of m-dinitribenzene per 25 mL sample. The dye shows a wavelength of maximum absorption at 530 nm. The dye is stable for ～ 30 h. Toluene, the major interferent, can be separated. Beer's law, sensitivity, reproducibility, and other reaction conditions such as time, temperature, and acidity were studied. Formation of stable dye is the main advantage of the method over the butanone method for benzene, in which the colored complex is stable for only 5 min. It is possible to determine traces of benzene (0.05–0.30 μg/mL) by extracting the azo dye in 10 mL iso-amyl alcohol; this also increases the stability of the dye up to 42 h.     

A pore water study of plutonium in a seasonally anoxic lake

Data are presented here on the distribution of ^239,240Pu in the pore waters of two cores taken from a seasonally anoxic lake. The pore water ^239,240Pu profile exhibits a subsurface activity maximum of 230 ± 30 μBqkg^?1 in the 3–6 cm interval in June, as compared to an activity of 5 ± 3 μBqkg^?1 in the overlying water. The pore water ^239,240Pu profile in June follows the solid phase distribution pattern of ^239,240Pu and also the pore water distributions of Fe and Mn. Under more reducing conditions in August, pore water ^239,240Pu activities drop off to undetectable levels at all depths. This rapid change in the pore water ^239,240Pu activity reflects the dynamic nature of Pu diagenesis in these sediments. Potential diffusional fluxes of ^239,240Pu into the lake's hypolimnion in June are calculated to be on the order of 2·5 μBq cm^?2y^?1. This flux would not be significant in altering the solid phase ^239,240Pu inventory (2·8 × 10⁴μBqcm^?2).     

Natural gamma-ray spectra of Terra rossa soil and phosphate ore

Gamma-ray spectra of terra rossa soil and natural-phosphate ore have been measured in order to determine Th, U, K and ¹³⁷Cs contents. It has been found that the phosphate ore contains an order of magnitude lower potassium content than average (n.10^?3g/g), an average content of thorium (n.10^?6g/g), and a two orders of magnitude higher concentration of uranium (n.10^?4g/g) than the averages found in the Earth's crust. Terra rossa contains two to three times higher concentrations of Th and U, average concentrations of K, and up to 0.2 Bq/g of ¹³⁷Cs. Both materials, in our opinion, are suitable for large-sample-calibration purposes and are applicable for radioecological studies of soils.     

Heavy metals uptake by Euglena proxima isolated from tannery effluents and its potential use in wastewater treatment

The flagellate, Euglena proxima, isolated from industrial wastewater showed tolerance against Cr⁶⁺ (20 μg/ml) and Pb²⁺ (30 μg/ml). The metal ions slowed down the growth of the organism after 4–5 days of exposure. The reduction in cell population was 68% for Cr⁶⁺ and 59% for Pb²⁺ after 8 days of metal stress. The order of resistance to heavy metals, in terms of reduction in the cellular population, was Pb²⁺ > Cr⁶⁺. Chromium and lead processing capabilities of Euglena proxima were worked out for its potential use as biore-mediator of wastewater. The reduction in the amount of Cr⁶⁺ after 7, 14 and 21 days of flagellate culturing containing 5 μg Cr⁶⁺/ml of culture medium was 76, 80 and 88%, respectively. Euglena proxima could also remove 78% Pb²⁺ after 7 days, 82% after 14 days and 90% after 21 days from the culture medium. The acid digestion of Euglena proxima showed 84% of Cr⁶⁺ and 88% of Pb²⁺ ions accumulated in the organism. The heavy metal uptake ability of Euglena proxima can be exploited for metal detoxification and environmental clean-up operations.     

The optimization of wastewater treatment via combined techniques: Part II: Combined biological—Dissolved air flotation

Optimum operating conditions for sewage treatment via combined biological-physico chemical treatment has been studied. The biological unit was a trickling filter. The non-settled biological effluent was subjected to coagulation followed by rapid solid-liquid separation via dissolved air flotation. The impact of organic load on the over-all efficiency of the system has been investigated using three different organic loads namely, 9.48, 20.0, and 27.85 g BOD₅m^?2d^?1. The coagulants used were ferric chloride and alum. Calcium oxide was used as a coagulant aid with ferric chloride. Factors affecting the efficiency of dissolved air flotation process such as detention time, air solids ratio, and position of coagulant's addition have been investigated. The results obtained showed that the use of biological, extended physico-chemical technique leads to the removal of organic as well as inorganic contaminants. Moreover, sludge with high solids content can be obtained.     

14C and 210Pb in NE atlantic sediments: Evidence of biological reworking in the context of radioactive waste disposal

Scavenging by the seabed and by sedimentary particles in the deep ocean may have a significant effect on the removal of artificial radionuclides released to the water column as a result of radioactive waste disposal operations. Biological activity in the upper layers of the sediment column will enhance the rate of removal for those particle-reactive radionuclides with a short half-life relative to the turnover time of the upper mixed layer. For longer-lived radionuclides the rate of sediment accumulation will determine the ultimate rate of removal.The rate of sediment accumulation and extent of biological mixing of deep-sea sediment from three areas of the NE Atlantic Ocean have been investigated using ¹⁴C and ²¹⁰Pb data. Treatment of the radiocarbon with a simple box model provided estimates of sedimentation rate (ω), mixed layer depth (L), mixed layer age (T_ML) and the age of material arriving at the surface (T₀), which were broadly similar to previously published values from other ocean basins. Box cores from the Iberia Abyssal Plain, Madeira Abyssal Plain and from the NEA low-level radioactive waste dumpsite yielded sedimentation rates in the range 0.8 to 2.2 cm ky^?1 over the upper 16–25 cm. Continuous particle mixing appears to be taking place to a depth of 4 to 6 cm below the present sediment-water interface. Closely spaced vertical sampling of core 161-2 for ²¹⁰Pb allowed a biodiffusion coefficient (D_B) to be calculated (4 × 10^?9cm²s^?1), treating bioturbations as a diffusive term and sedimentations as an advective term in a simple mathematical model. In general, values of D_B in deep ocean sediments fall within the range 1–10 × 10^?9cm²s^?1, two orders of magnitude lower than nearshore values. From a review of published data it is concluded that biological mixing takes place extensively in the deep ocean; it appears to be fairly constant on a basin-wide scale and amenable to incorporation in mathematical models of radionuclide behaviour in the water column.     

Ambient air pollution and children's lung function in China

ObjectiveTo describe the correlations between ambient air pollutants (TSP, SO₂, NO_x) and the level of children's lung function (FVC, FEV₁, MMEF) in China.MethodsWe collected the research articles on ambient air pollution and children's lung function published from 1985 to 2006 and selected 11 articles finally according to the following criteria: (1) Children between the age of 7 and 15 as objects; (2) Local air quality monitoring results were reported; (3) Strict quality control was taken when testing children's lung function; (4) The results were expressed by the average of measured value. Then we analyzed the correlation relationship between the level of ambient air pollutants and children's lung function and compared the effects of ambient air pollutants on children's lung function of boy and girl.ResultsThe selected articles included the results of 7 cities in China. Among them, the results of 6 cities' studies revealed that the levels of children's lung function were significantly lower in the areas with heavy ambient air pollution than those in the areas with light ambient air pollution. According to the articles, the average levels of TSP were at the range of 0.084 mg/m³–0.835 mg/m³, SO₂ were 0.013 mg/m³–0.929 mg/m³, NO_x were 0.044 mg/m³–0.229 mg/m³. Correlation analysis showed significant negative correlation between the levels of TSP and SO₂ and children's FVC and FEV₁, as well as the levels of NO_x and children's MMEF. The correlation coefficient was ? 0.797 (t = ? 4.384, P = 0.001) between TSP and FVC, ? 0.693 (t = ? 4.190, P < 0.001) between Ln (SO₂) and FVC, ? 0.886 (t = ? 5.392, P = 0.001) and ? 0.685 (t = ? 4.101, P = 0.001) between FEV₁ and TSP and Ln (SO₂), and ? 0.973 (t = ? 5.993, P = 0.027) between NO_xNO_x and MMEF, respectively. The results also suggested that the decreases of lung function for girl with the increasing of ambient air pollution were significantly greater for boy.ConclusionThe levels of ambient air TSP and SO₂ correlated with the damage of the big airway function of children, while NO_xNO_x affected the small airway function chiefly. Furthermore, lung function of girl was more susceptible to ambient air pollutants than boy.     

Greenhouse gases emissions from a closed old landfill cultivated with biomass crops

Closed landfills need after-closure rehabilitation. The chosen option should ensure greenhouse gases release, from the landfill, is not promoted once settled. The objective of this study was to estimate and confront, during different seasons, CH₄, CO₂ and N₂O emissions under three vegetation covers in a closed landfill in Buenos Aires, Argentina. CH₄ (methane), CO₂ (carbon dioxide) and N₂O (nitrous oxide) emissions from landfill’s technosol under spontaneous vegetation (control), Pennisetum purpureum and Miscanthus giganteus (biomass crops), were quantified with non-steady-state non-flow-through chambers, in July 2014 and from February to July 2015. A linear regression analysis was performed to relate the variables “flux of a gas” and “concentration of that gas” from the 3 treatments and 6 dates, separating the 5 sampling times. A high correlation between concentrations and fluxes of CO₂ and N₂O was found, but no correlation was established for CH₄. Mean emissions (2014–2015) varied from: ?2.3 to 639.41 mgCH₄ m^?2 day^?1, 3884 to 46,365 mgCO₂ m^?2 day^?1 and 0.40 to 14.59 mgN₂O m^?2 day^?1. Vegetation covers had no significant effect on CH₄ and N₂O concentration in time, but they had on CO₂ concentration. Season of the year had a significant effect on concentration of the three gases. This is the first study on CH₄, CO₂ and N₂O emissions from a landfill closed 27 years ago covered with biomass crops.     

Effects of short-term ozone exposure on net photosynthesis,dark respiration,and transpiration of three eastern white pine clones

Net photosynthesis, dark respiration, and transpiration rates were determined during ozone (O₃) exposure for three clones of eastern white pine (Pinus strobus L.) differing in sensitivity to O₃. Fumigations for 4 h with 0.10, 0.20, and 0.30 μL/L O₃ inhibited net photosynthesis of all three clones. Light transpiration was inhibited in both the sensitive and the tolerant clones and was not affected in the intermediate clone. Recovery of net photosynthesis and light transpiration occurred 1 h after the termination of ozonation, with the degree of recovery depending upon clonal sensitivity to O₃ and the O₃ concentration used. Dark respiration increased in the O₃-sensitive clone only, and dark transpiration was unaffected in all three clones after 4-h exposure to 0.30 μL/L O₃. Ozone-induced inhibition of net photosynthesis and stimulation of dark respiration are discussed in relation to clonal sensitivity to O₃.     

Actual evapotranspiration and canopy resistance measurement of the savannah in the Kouilou basin (Congo-Brazzaville)

The aim of this work is to study the actual evapotranspiration and surface resistance of the savannah using the Bowen-ratio method for two contrasted periods, dry and rainy season. The reliability of this method has been assessed by comparison with the Monteith equation and the soil-water balance method in a 90% Loudetia arundinacea dominated savannah (Pointe Noire, Congo). Our results relate to the period from 18 September to 11 October 1998 (24 days): (a) from 18 to 29 September (“dry season”), the soil-water content was less than 70% of the soil-water content at field capacity (63–70% of R _FC; large soil-water stress; T/E _P from 0.2 to 0.4); (b) from 30 September to 11 October (“rainy season”) soil-water content close to 90–92% of RFC; no soil-water stress; T/E _P from 0.73 to 0.77). The mean daily surface resistance reulting from the Bowen-ratio method was 317 s m^?1, 355 s m^?1 during the “dry season” and 279 s m^?1 during the “rainy season”. The total actual evapotranspiration (E _a) resulting from the Bowen-ratio method, Penman-Monteith equation and soil-water balance method were, respectively of 58.6–57.8 and 56.2 mm, with the mean daily E_a of 2.4–2.4 and 2.3 mm day^?1 (2.4–1.5 and 2.2 mm day^?1 in “dry season” and of 2.5–3.4 and 2.5 mm day^?1 in “rainy season”). The Bowen-ratio method was used for the assessment of the actual evapotranspiration from the temperature and specific humidity differences, net radiation and the soil heat flux measurement: its advantages are a rapidity of installation, a temporal resolution of measurement in less than one hour and a good integration of the heterogeneousness of the savannah’s latent flux of vaporization. This method is adapted to eco-physiological studies in tropical conditions with reduced teams.     

Citric and Oxalic Acids Effect on Pb and Zn Uptake by Maize and Winter Wheat

Abstract

A pot experiment was conducted to investigate the influence of citric and oxalic acids effect on Pb and Zn uptake by corn and winter wheat. The experiment was employed with citric acid (CA) applied at 3 rates (0, 1.5 and 3.0 mmol kg^?1 soil), oxalic acid (OA) at 3 rates (0, 1.5 and 3.0mmol kg^?1 soil) and citric acid combined with oxalic acid (1.5 mmol citric acid combined with 1.5 mmol oxalic acid kg^?1). Two types of soil were chose in the experiment. One was collected from the agricultural soil near a battery-recycling factory in Anhui province, China (site A) and the other was collected from a Pb-Zn mine residues in Hunan province, China (site B). The results showed that soil pH varied with the different treatment of citric and oxalic acids. However, there were no differences in all the treatments. 3.0mmol CA kg^?1 soil addition significantly increased the concentrations of the CaCl₂-extractable Pb and Zn and other treatments have no significantly increased. The highest shoot concentrations of Pb and Zn in both species occurred in application of 3.0 mmol CA/kg^?1 soil and shoot concentrations of Pb and Zn in both species were significantly higher than the controls in this treatment. Shoot yields declined with application of citric and oxalic acids, indicating that the plants were sensitive to the toxicity of the metals or the amendments. The highest Pb uptake values by maize and wheat werell2.3 and 77.2 μg pot1 in soil of site A, and occurred with the control and 3.0 mmol CA/kg^?1 soil respectively.     

The distribution and inventory of fallout plutonium in sediments of the Ligurian Sea near La Spezia,Italy

Pu concentrations in surface sediments of the Ligurian Sea are about ten times higher than in adjacent river sediments and are highly correlated with sediment porosities. The integrated inventory of ^239,240Pu in a sediment core is calculated to be 3·5 mCi km^?2, nearly twice the average input from fallout at these latitudes, apparently because Pu is removed from seawater by particle scavenging.The sedimentation rate is calculated from the depth of the ^239,240Pu maximum to be 0·52 ± 0·06 cmy^?1.     

Effect of cigarette smoking on residential NO2 levels

Two studies evaluating the levels and sources of nitrogen dioxide in approximately 90 employee homes in the Richmond area with continuous sampling during the weeks of August 5, 1980, and February 9, 1981, were performed using samplers in the living room, bedroom, kitchen, and outdoors. Additional data were collected concerning appliance usage, heating/cooling plant, ventilation and cigarette smoking. Results were analyzed using BMDP routines. The largest contributor to NO₂ concentration was found to be gas-fired kitchen appliances. The mean kitchen level for homes with gas appliances during the winter study was 188 μg/m³. Excluding participants with gas kitchens, incremental influence due to cigarette smoking was detected. The 7-day, 3-room average level of NO₂ in the homes of nonsmokers and smokers without gas-fired appliances was 12 and 15 μg/m³, respectively, in the summer. The corresponding winter values were 19 and 22 μg/m³. Furthermore, the individual levels of NO₂ in the homes of smokers were generally below both the adjacent outdoor level and the National Ambient Air Quality Standard limit for annual exposure.     

Non-agglutinating cholera-like Vibrios in sewage,surface water and sea water

Routine bacteriological analysis of sewage work effluents and surface waters has not revealed evidence of Vibrio cholerae or Vibrio El Tor, whereas, non-agglutinating cholera vibrios of Heiberg's groups I and II [so-called non-agglutinating strains (NAG)] have been detected quite frequently. This frequency of NAG presence is approximately equivalent to the presence of Salmonella. Depending on local conditions, quantitative studies of equal amounts of sewage resulted in a ratio of about 1 NAG/10²Salmonella/10⁷E. coli.When it became known that NAG vibrios were capable of producing a clinical appearance in man that resembled cholera by its symptoms and severeness, NAG vibrios raised epidemiological interest. Unlike Salmonella, the nutrient requirements of NAG vibrios are moderate. The decisive factors for their persistence in the environmental are attributed to a certain chloride content in the water and an elevated pH value. Both factors are preferably present in sea water. Over a period of 3 yr, samples of water from the Baltic Sea (Lübecker Bucht) were regularly examined for the presence of NAG vibrios. During this period, there have been a number of positive findings in a sample of 100 ml water while identical samples were always Salmonella-negative.     

Contrasting impacts of climate change across seasons: effects on flatfish cohorts

The Senegal sole, Solea senegalensis, is a species of flatfish that has several distinct cohorts of 0-group juveniles which use estuarine nurseries in summer and winter. The early cohort is more abundant and grows faster than the late cohort that stays in the nurseries during winter; however, climate warming may have an impact on the dynamics of this species’ juveniles. This study aimed to compare mortality, metabolic response and growth of S. senegalensis juveniles at different temperatures, reflecting present-day temperature (winter—12 °C; summer—24 °C) and future temperature (plus 3 °C) conditions, in estuarine nurseries in the southern European population. Mortality was low at 12 °C, being only 10 %, increasing to 30 % at 15 °C, 40 % at 24 °C and at 27 °C it hit 70 %. Metabolic rate increased steadily with increasing temperatures, yet it increased steeply from 24 to 27 °C. Thermal sensitivity was high for the temperature interval between 24 and 27 °C. Growth was very slow at 12 °C, at a rate of 0.03 mm day^?1, increasing to 0.22 mm day^?1 at 15 °C, and to 0.60 mm day^?1, at 24 °C. However, at 27 °C growth rapidly declined to 0.12 mm day^?1. Warming will be beneficial for the late cohort, resulting in a major increase in growth. However, the early cohort will not benefit from warming, due to high mortality and arrested growth, which clearly indicates that this species is under severe thermal stress at 27 °C. Thus, here we show, for the first time, that climate change may induce contrasting seasonal impacts on fish bio-ecology and physiology, namely in species with several cohorts over the course of the year. Phenotypic and/or genotypic plasticity may limit the impacts of climate change.     

Effect of sample conditioning and chamber loading on rate of formaldehyde release from wood products in a desiccator test

Several variables may influence the observed rate of formaldehyde (CH₂O) offgassing from wood products in a small static test chamber. We studied the effect of sample conditioning at ≈100% relative humidity and chamber loading (sample size) on CH₂O release rate from particle board (PB) and plywood (PW). Samples of PB and PW were placed in glass desiccators with reservoirs of water at a loading of 21 m²/m³ (sample surface area per chamber volume). The rate of CH₂O offgassing from the PB did not change over several weeks under these conditions (0.24 μg/cm²/day), but the overall release rate from the PW decreased after 8 days. In another experiment, the loading of the desiccator had a major effect on the rate of CH₂O offgassing from PB over a loading range of 1 to 42 m²/m³. The same phenomenon was observed with different loadings of PW. The inverse of the observed release rate varied linearly with the chamber loading of PB or PW. At a loading which may be encountered in a house (0.25 m²/m³), the release rate coefficient for PB calculated from the above inverse relation was 22-fold higher than that measured at a more conventional test load of 21 m²/m³. These results indicate that great care should be exercised when using desiccator tests for assessing and comparing the potential strength of materials as sources of CH₂O in the indoor environment.     

Odor-annoyance estimates from roadtraffic combustion exhausts: Calibration with master scaling using pyridine as a reference

The present field study addressed the need for a procedure that provides a defined unit of measurement of perceived annoyance from environmental odors, calibrating the estimates for individual scaling behavior and context effects. In including 25 subjects, the purpose was to demonstrate the applicability of the master-scale procedure with magnitude estimation to perform such a calibration of odor-annoyance estimates for target stimuli such as road-traffic combustion exhausts (13 000 vehicles/d; averaging 47 μg/m³ over the day/night with peaks exceeding 100 μg/m³ of nitrogen dioxide; NO₂). For comparison, calibrated estimates were also obtained for a backyard expected to be considerably less polluted (comparable with 18 μg/m³ of NO₂) and for blank stimuli presented indoors. The data transformation for the calibration procedure with which annoyance is expressed in either master-scale units or pyridine equivalents requires estimates of a reference stimulus for which seven concentrations of pyridine were used. The results provide an illustration of master scaling of odor annoyance, and imply that use of a modulus (standard stimulus with a predefined annoyance magnitude), in contrast to master scaling, is not sufficient for calibration for individual scaling behavior and context effects.     

Ecophysiology of Steppe Mouse Subspecies <Emphasis Type="Italic">Mus spicilegius spicilegus</Emphasis>, Peteni, 1883 (Rodentia,Mammalia) at the South Boundary of its Distribution

Diet, food preferences and main ecophysiological characteristics such like energy requirements and thermoregulation characteristics of Mus spicilegus spicilegus (Petenyi, 1882) were studied. The most preferred foods for the mice were seeds of weed species that composed more than 85% of their diet. The results of food selection experiments shows that the total daily consumption by mice is 2.77 ± 0.76 g/animal/day or 5.5 kJ/g/day or 84.9 kJ/animal/day. From the total daily energy consumption 16.4% go back to nature in the form of feces and urine and the rest 83.6% animals utilized for assimilation. The results of the temperature preferences for Mus s. spicilegus shows preferred temperature zone from around 26 to 36°C where mice spent about 72% of the experimental time. The lowest value of oxygen consumption for resting metabolism rate (RMR) was registered at 30°C–3.20 ± 0.71 cm³ O₂/g/h. It is possible to consider that the thermoneutral zone is around these temperature values. The obtained results give reason to conclude that from an ecophysiologycal point of view the climate in the south boundary of distribution provides optimal conditions for species development. The main cause for population decreasing probably is the loss of open habitats including natural steppe grasslands.     

Suspended particulate matter in dwellings — the impact of tobacco smoking

The indoor concentration of suspended particulate matter (SPM) was measured in forty-four retrofitted and tight dwellings, which had electric cooking and were central heated and where the basic ventilation rate in median amounted 0.23 air changes per hour as measured with a tracer dilution method. The indoor concentration of SPM was in median 230 μg/m³ with a strong correlation to the tobacco consumption (r_s=0.716), but with no correlation to the frequency of airing or the basic ventilation rate. Tobacco smoking seems to be the main indoor source of SPM in contemporary dwellings. The importance of these findings is underlined by epidemiologic studies on passive smoking and health. Air quality standards for the ambient air are based on certain risk groups such as infants, children, persons with chronic obstructive lung disorders, and indoor air standards should be based on the same concepts of health protection.     

Solar-driven technology for freshwater production from atmospheric air by using the composite desiccant material “CaCl<Subscript>2</Subscript>/floral foam”

In this communication, experiments have been performed to check the capability of the newly formed composite desiccant material (CaCl₂/floral) for the extraction of freshwater from atmospheric air. Three numbers of solar glass desiccant box type system (SGDBS) with a captured area of 0.36 m² each, have been used. The design parameters for the water production are height of glass from desiccant bed at 0.22 m, inclination in angle as 30°, the effective thickness of glass as 3 mm and number of glazing as single. The maximum yield by the new composite desiccant material is 0.35 ml/cm³/day. The efficiency of the system SGDBS with 37 % concentration of CaCl₂ is 76.44 %.