果尔对水稻土中厌氧细菌的影响

探讨了各种浓度的果尔对水稻土中厌氧细菌群的影响,实验表明,低于或等于田间正常施药量的果尔,在１周内对各类氧细菌的生长具有刺激作用,随着施药后时间的延长,刺激作用逐渐消失;高于田间正常施药量的果尔,在１周内对各类厌氧细菌的生长具有明显的抑制作用,随着施药后时间的延长,果尔的降解产物能促进各类厌氧细菌的生长。     

Time aggregation of nitrogen leaching in relation to critical threshold values

Leaching of nitrate contributes to the deterioration of groundwater and can consequently have a negative influence on the quality of our drinking water. Critical threshold values for nitrogen leaching are established to preserve groundwater quality. A critical threshold value for nitrate leaching of 50 mg 1⁻¹ (11.3 mg N 1⁻¹), similar to the drinking water standard, serves as a threshold value for European countries. However, the temporal aggregation scale on which this threshold value should be considered is unknown. A well tested simulation model was used to evaluate the exceedance of the threshold value at different time aggregation levels, ranging from one day till 30 yr. For three different soil structure types within one soil type and a selected fertilisation regime, the aggregated nitrogen leaching over 30 yr was 11.4, 19.2 and 10.6 mg 1⁻¹. Considering an aggregation level of one day, the critical threshold value of 11.3 mg N 1⁻¹ was exceeded 2973, 5801 and 2556 times, respectively, for the three structure types during 30 yr. By considering other time aggregation levels, a clear relation resulted between time aggregation level and the number of time elements during which the critical level was exceeded. Results strongly indicate that a critical threshold value for leaching should include an associated time-aggregation level.     

Investigation of photodegradation and hydrolysis of selected substituted urea and organophosphate pesticides in water

Introduction  

Photodegradation and hydrolysis of two substituted urea herbicides, monolinuron [3-(4-chlorophenyl)-1-methoxy-1-methylurea] and linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea], and one organophosphorous insecticide, phoxim [2-(diethoxyphosphinothioyloxyimino)-2-phenylacetonitrile], were studied using buffered sterilized distilled water (pH 4, 7 and 9).     

Usefulness of the Finnish classification of indoor climate,construction and finishing materials: comparison of indoor climate between two new blocks of flats in Finland

Two seven-storied blocks of flats were investigated: one was built in the conventional way (control building) and the other by following the instructions of the Finnish Classification of Indoor Climate, Construction and Finishing Materials (case building). Indoor air parameters were measured in one apartment on each floor of both buildings before occupants moved in and after a 5-month occupancy. The ventilation system was kept at a high capacity in the case building for one week after its completion before occupants moved in the building. In the case building, the most demanding class S1 target levels for the room temperature, RH, CO₂, formaldehyde, and the total suspended particles were already achieved before the occupants moved in the building and the target levels for CO, TVOC and ammonia were reached 5 months later. Only the S1 target level for odor intensity was failed to achieve. In general, the levels of indoor air impurities in the case building were initially lower and they remained on a lower level during the occupancy than those in the control building mainly because of the use of low-emitting materials and a higher ventilation rate. In the case building, the 1-week ventilation period reduced the TVOC levels approximately by 50%. This study proved that good indoor air quality can be achieved by careful design, choice of proper materials and equipment, and on high-quality construction.     

Analytical Performance of Four Portable Gas Chromatographs Under Field Conditions

A field evaluation of the performance of four portable gas chromatographs was conducted at two field sites, one in the Pacific Northwest (chlorinated solvent contamination) and one in the Desert Southwest (primarily jet fuel contamination). The purpose of the study was to compare the performance of four portable GCs under the same conditions. The gas chromatographs had either electron-capture detectors or photoionization detectors. The study evaluated instrument linearity, instrument detection limits, retention time stabilities, response factor stability, and chromatographic performance. Standards and samples contained 1, 1, 2, 2-tetrachloroethane, trichloroethene, tetrachloroethane, 1, 1, 1-trichloroethane, benzene, toluene, and ethylbenzene. In order to ensure data comparability, the same model wide-bore column and computing integrator were used with each instrument, where possible. Significant differences in the performance of the four models were detected under the specific conditions used for this study. The results indicate the need to fully characterize the performance of portable instruments before field use so that appropriate quality control measures can be planned and implemented based on the performance of a specific analytical system.     

Evaluation of watering to control dust in high winds

A field study was conducted to determine the effectiveness of watering in controlling PM10 emissions under high wind conditions. The focus of the study was the pickup of soil by a belly scraper at a landfill. Four low-volume PM10 samplers were positioned downwind of the storage pile (at two distances, 80 and 110 m, and two elevations, 1 and 3 m) and one was located upwind at 3 m elevation. Integrating nephelometers, which measure the particulate light scattering coefficient, bsp, were also set up at locations 80 and 110 m downwind of the storage pile. Wind speed and direction were measured on-site. Samples were collected for two periods, one with and one without water being applied. Watering was effective at reducing PM10 emissions at wind speeds up to the maximum 18 m sec-1 observed at the landfill soil pickup operation. Measurement of bsp provided an indication of PM10 concentrations with better time resolution than samplers, but not with sufficient resolution, under the instrumental conditions used, to correlate with wind gusts.     

Anti-kindling effect of Ginkgo biloba leaf extract and L-carnitine in the pentylenetetrazol model of epilepsy

Environmental Science and Pollution Research - Epilepsy is one of the most common serious brain disorders, affecting about 1% of the population all over the world. Ginkgo biloba extract (GbE) and...     

SCR反应器内各关键部件对系统压力损失特性影响的研究

选择性催化还原(selective catalytic reduction,SCR)脱硝反应器的关键部件对系统压力损失特性的影响非常明显.针对某电厂1×300 MW锅炉机组的SCR脱硝反应器,采用数值模拟和实验研究的方法研究了各关键部件对系统压力损失特性影响.通过研究确定了SCR反应器的最优设计方案,即关键部件1设计为...     

Occurrence of PCDD/Fs in urban air before and after the ban of leaded gasoline

The source of PCDDs and PCDFs in automotive exhaust is not yet fully explained. The chlorinated hydrocarbons used in the formulation of lead-alkyl additives were suspected as a possible major source. Based on this, the decreasing use of leaded gasoline followed by its final ban (occurred on 1/1/2002, in Italy) should have resulted in a decreasing presence of PCDD/Fs in urban air and possibly some differences in their profile. To investigate these aspects, we monitored PCDD/Fs for one year starting in September 2001, at a medium-traffic road site in Rome, with weekly frequency. Results were then compared with those obtained in a previous study performed before the ban (from February 2000 to January 2001) at the same site. As compared with the previous study, the yearly-averaged overall PCDD/F concentration, as toxic equivalent of 2,3,7,8-TCDD, decreased from 60 to 50 fg m(-3) I-TEQ; it remained unchanged, however, if one sample with a particularly high PCDD/F content was excluded from each data set. The monthly trend confirmed the one found in the former study. On an annual basis, the two mean congener profiles were almost identical. The concentration levels and the constancy of profiles, as calculated for the two periods, do not support the hypothesis of a major role of leaded gasoline, substantially different from unleaded one, in contributing to PCDD/F air pollution.     

Cemetery waste as a substream of municipal waste: research and structure of the selective waste collection in Poland

Environmental Science and Pollution Research - Cemetery waste (CW) constitutes one of the streams of municipal waste (MW). Based on the available data, it can be said that it accounts for about 1%...     

Biochemical characterization of a multiple heavy metal, pesticides and phenol resistant Pseudomonas fluorescens strain

Pseudomonas fluorescens SM1 isolate was found to be resistant to some major water pollutants namely Cd2+, Cr6+, Cu2+, Ni2+, Pb2+, BHC, 2,4-D, mancozeb and phenols up to a concentration four times to the normal levels occurring in the highly pollulated regions. Curing experiment brought about the loss of one or more resistance markers indicating the plasmid born resistance. Plasmid profile of SM1 strain showed the presence of one DNA band of 43.6 kb. This Plasmid was isolated from SM1 strain and introduced into Escherichia coli DH5 alpha with a transformation frequency of 6.7 x 10(-4)transformants/recipient cell. The test SM1 strain was also capable of biotransforming Cr(VI) to Cr(III) which is less toxic compounds. Present studies further indicated that the test SM1 strain was not only resistant to 2,4-D, phenols and catechol but also capable of bioremediating these toxicants quite efficiently. Moreover, studies with inhibitors like sodium azide, 2,4-DNP and chloramphenicol suggested that the major mechanism for the bioremediation of the heavy metals other than Cr6+ would be the biosorption process.     

Phytoscreening and phytoextraction of heavy metals at Danish polluted sites using willow and poplar trees

The main purpose of this study was to determine typical concentrations of heavy metals (HM) in wood from willows and poplars, in order to test the feasibility of phytoscreening and phytoextraction of HM. Samples were taken from one strongly, one moderately, and one slightly polluted site and from three reference sites. Wood from both tree species had similar background concentrations at 0.5 mg kg^?1 for cadmium (Cd), 1.6 mg kg^?1 for copper (Cu), 0.3 mg kg^?1 for nickel (Ni), and 25 mg kg^?1 for zinc (Zn). Concentrations of chromium (Cr) and lead (Pb) were below or close to detection limit. Concentrations in wood from the highly polluted site were significantly elevated, compared to references, in particular for willow. The conclusion from these results is that tree coring could be used successfully to identify strongly heavy metal-polluted soil for Cd, Cu, Ni, Zn, and that willow trees were superior to poplars, except when screening for Ni. Phytoextraction of HMs was quantified from measured concentration in wood at the most polluted site. Extraction efficiencies were best for willows and Cd, but below 0.5 % over 10 years, and below 1?‰ in 10 years for all other HMs.     

The influence of chlordecone and oestrogen on the secretion of proteinaceous molecules of the mouse uterus

Ovariectomised mice were treated with sesame seed oil, oestradiol, or one of three different levels of the insecticide chlordecone (1, 1a, 3, 3a, 4, 5, 5a, 6-decachloro-octahydro-1, 3, 4-metheno-2H-cyclobuta[cd] pentalen-2-one). After 9 days of treatment, the uteri were injected with (35)S-methionine and radiolabelled proteins were flushed from uteri 4 h later. Reproductive tract weights and the total amount of radioactivity in uterine flushings were measured. Reproductive tract weights increased significantly only in animals treated with the highest dose of chlordecone tested and oestradiol-treated animals. Trichloroacetic acid (TCA) precipitated radioactivity was increased by all doses of insecticide chlordecone tested but increases were significant only at one level. The greatest stimulation of (35)S-methionine incorporation occurred in ovariectomised animals treated with oestradiol. Radioactive proteins were analysed by fluorography of two-dimensional gels. The fluorograms showed that the proteinaceous uterine secretions, as influenced by chlordecone, were greatly reduced in number as compared with those secreted under the influence of oestradiol. Chlordecone appears to cause the secretion of proteinaceous material from the uteri of mice in a qualitatively different manner than does oestradiol.     

Dissipation of s-triazines and thiocarbamates from soil as related to soil moisture content

Half-lives (t1/2) of two soil incorporated s-triazines (atrazine and prometon) and two thiocarbamate (EPTC and triallate) herbicides were determined in relation to soil moisture content in two California soils. Treated soils were incubated at three moisture levels in aerated glass vials at 25 +/- 1 degree C and were analyzed at 0, 7, 16, 28, 56 and 112 day intervals. Loss of herbicides in all treatments followed first-order kinetics. The t1/2-values of all herbicides decreased with increasing soil moisture and followed an empirical equation, t1/2 = aM(-b) (where t1/2 is half-life; M the moisture content; and a and b are constants). Soil moisture had a greater effect on carbamates than on s-triazines . Prometon exhibited the longest half-life in both soils, whereas EPTC was least persistent in one soil and atrazine in another. The t1/2-values for atrazine, prometon, EPTC, and triallate with medium moisture levels and 10 microg/g concentration were 34.6, 43.2, 25.4 and 38.1 days in sandy loam and 26.5, 44.4, 44.1 and 25.9 days in loamy sand, respectively. Disappearance of 50% of the applied concentrations of most of the herbicide-soil combinations (except EPTC and triallate in one soil) took longer for lower initial concentrations (1 microg/g) than for higher concentrations (10 microg/g).     

Antimony mobility in Japanese agricultural soils and the factors affecting antimony sorption behavior

The mobility of antimony (Sb) in Japanese agricultural soils was studied by radiotracer experiments using 124Sb tracer. The soil-solution distribution coefficients (Kd) of Sb were measured for 110 soil samples. These Kds ranged from 1 to 2065 L kg(-1); the geometric mean was 62 L kg(-1) excluding one extremely high value, 2065 L kg(-1). Experimental measurement of Kd showed a decrease with both increasing pH and increasing phosphate concentration. The latter suggested that one aspect of the Sb sorption phenomena in Japanese soil was influenced by specific adsorption of anions such as phosphate. However, other aspects could not be explained by this specific adsorption mechanism, because only 20-40% of soil-sorbed Sb could be extracted by phosphate solution.     

Single-Stage Dewatering of FGD Waste

The Escalante Unit No. 1 flue gas desulfurization (FGD) waste slurry dewatering system represents the first domestic utility to deviate from the typical industry two-stage dewatering system design. Evaluations conducted during the design phase compared three dewatering options: 1) thickener in series with vacuum filters, 2) thickener in series with centrifuges, and 3) centrifuges with no thickener. The evaluation showed that centrifuges with no thickener (one stage) could significantly reduce capital costs. Coupled with capital costs, this option also decreases operation and maintenance costs, reduces the complexity of the system, saves a considerable amount of space, and centralizes the FGD and dewatering systems within one building. This paper describes the evaluation that took place during the design phase of the project comparing the three dewatering options. Operational data for the first year of operation are presented, and operating and maintenance costs are discussed and compared with conventional two-stage dewatering systems.     

Development and application of methodology for determining 1,2‐dibromo‐3‐chloropropane (DBCP) in ambient air

Abstract

Ametpreviously described by Mann et al.¹ for the determination of hexachlorobenzene in air was modified to detect DBCP in air at the level of 0.02 ppb (by volume). The method utilizes Chromosorb 101 as a trapping medium with subsequent analysis of the eluted DBCP by electron capture ‐ gas chromatography. The procedure was tested using air flows of 1 1/min to 5 1/min for sampling periods of 30 min to 3 hr. Recoveries of greater than 90% were obtained for DBCP levels ranging from 0.07 ppb to 20 ppm. More than 90% of the DBCP stored on Chromosorb 101 at ambient temperature for one month was recovered. A one‐half acre field plot was sprayed with DBCP using the drench method. Air samples were taken from the breathing zone of the applicator during the mixingspraying and clean‐up procedures. Air samples were also taken periodically around the perimeter of the plot for up to 7 days after spraying.     

Polybrominated diphenyl ethers and HBCD in bird eggs of South Africa

In this paper, the first data on brominated flame retardants (BFRs), in particular polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) in eggs of bird species from South Africa are described (N=43). Concentrations of PBDEs were detected in all the studied species and in all the geographic areas. Highest concentrations of PBDEs were measured in bird eggs from the Vaal River, which is situated downstream of the most industrialized area in South Africa. Sum-PBDE concentrations were highest in eggs of one African sacred ibis (396 ng g(-1) lipid weight (lw)), possibly due to foraging on dumping sites. Lowest mean level of sum-PBDEs (2.3 ng g(-1) lw) was measured in cattle egrets (N=11) from Barberspan Sanctuary, a Ramsar site. The PBDE congener pattern showed large differences, reflecting different trophic levels, migratory behavior, distance to the source, and, exposure to different PBDE mixtures, among others. HBCD was detected only in four species, and highest levels were measured in one egg of African sacred ibis (71 ng g(-1) lw). In most species, levels of PBDEs were one to several orders of magnitude lower than levels of DDTs and PCBs. PBDEs correlated strongly with DDTs, PCBs and some other organochlorines (OCs), indicating the same source. The widespread occurrence of PBDEs in the South African avian species showed a strong need for further investigations of PBDEs in the Southern African environment.     

Measurement of atmospheric deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans in the Lagoon of Venice, Italy

Data on atmospheric fall-out of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were provided by collecting bulk deposition in four stations inside the Lagoon of Venice. A total of 44 monthly samples was collected during the period July 1998-July 1999 in one site near an industrial area (Porto Marghera), one site in the city of Venice, and two sites in the southern- and northernmost ends of the Lagoon. Fluxes of PCDD/Fs were between 0.1 and 470 pg m(-2) d(-1), corresponding to 0-9.2 pg of 2,3,7,8-TCDD equivalents (TEQ) m(-2) d(-1), with a gradient increasing from remote to urban/industrial stations. Thus, annual deposition of PCDD/Fs to the Lagoon (total area=550 km2), calculated with various methods, turned out to be approximately 12 g, corresponding to approximately 400 mg TEQ. Significant differences were found among the stations, with a clear fingerprinting signature (PCDF/PCDD>1) of the deposition collected near Porto Marghera, and a reversed pattern (PCDF/PCDD<1) in the rest of the Lagoon, which pattern was similar to the sediments collected in the same locations. Lastly, the amount of bulk sigmaTEQ of all stations was compared with the guide values for dioxins in depositions proposed by De Fré et al. [Organohalogen Compounds 45 (2000) 324].     

Management of hazardous fly-ash energy waste in the adsorptive removal of diclofenac by the use of synthetic zeolitic materials

Zeolite-carbon composites (Na-P1(C), Na-X(C)) and pure zeolites (Na-P1, Na-X) were synthesized from hazardous high-carbon fly ash waste (HC FA) via hydrothermal reaction with sodium hydroxide (NaOH). These solids were applied in the removal of diclofenac (DCF) from aqueous solution, with and without poly(acrylic acid) (PAA). The experiments included adsorption–desorption measurements, as well as electrokinetic and stability analyses. The obtained results showed that HC FA and Na-P1(C) had the greatest adsorption capacity towards DCF, i.e., 26.51 and 21.19 mg/g, respectively. PAA caused considerable decrease in the DCF adsorption due to the competition of both adsorbates of anionic character for active sites. For example, the adsorbed amount of DCF on Na-P1 without PAA was 14.11 mg/g, whereas the one measured with PAA was 5.08 mg/g. Most of prepared solids were effectively regenerated by the use of NaOH. Desorption degree reached even 73.65% in the single systems (with one adsorbate) and 97.24% in the mixed ones (with two adsorbates). Zeolitic materials formed suspensions of rather low stability, which underwent further deterioration in the organic molecules presence. All the results obtained in this study indicated that HC FA can be successfully managed in the removal of organic substances.