首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
C.M. Tu 《Chemosphere》1982,11(10):1027-1033
The relative toxicity of 23 pesticides, including 21 fungicides and two pyrethroid insecticides, on Rhizobiumjaponicum, four soybean pathogens, Fusariumoxysporum, Phytophthoramegasperma, Phytophthoraparasitica and Pythiumultimum, and germination of soybean seeds was compared with a highly toxic broad spectrum germicide, HgCl2 under laboratory conditions.  相似文献   

2.
For the determination of the quantum yields of 1,2,3,4,7-pentachlorodibenzo-p-dioxin (1) and 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (2), ten Pyrex glass photochemical cells were constructed and their correction factors determined. Quantum yields at 313 nm for 1 and 2 in aqueous acetonitrile (4:6 v/v) were (9.781 ± 2.376) 10?5 and (1.096 ± 0.020) × 10?4, respectively. These quantum yields and the measured absorption spectra were used to estimate the environmental phototransformation first-order rate constants and photochemical half-lives of 1 and 2 in water under conditions of variable sunlight intensity during various seasons from solar intensity data available in the literature. In summer, typical half-lives for the phototransformation of 1 and 2, respectively, near the surface of water bodies at 40° north latitude would be 364 ± 88 and 151 ± 3 h; whilst such values in winter would be 1257 ± 309 and 518 ± 10 h.  相似文献   

3.
Photolysis (254 nm, 72h) of 1-nitro-2-phenylnaphthalene 1 in methanol gave 2-phenyl-1,4-naphthoquinone-4-monoxime 2, 2,2′-diphenyl-4,4′-binaphth-1,1′-diol 3 and 2,2′-diphenyl-4,4′-binaphth-1,1′-dione 4. Straightforward reactions available to the environment account for the formation of the products: (a) isomerisation of the nitro compound into a nitrite ester followed by either (a) migration of the nitroso group and isomerisation into the oxime 2 or (b) oxidative coupling and solvolysis into the binaphthol 3 and followed by oxidation into the binaphthone 4.  相似文献   

4.
P. Miramand  M. Unsal 《Chemosphere》1978,7(10):827-832
Acute toxicity of vanadium to some marine benthic and phytoplanktonic speciesThe acute toxicity of vanadium as sodium metavanadate to three benthic (Carcinusmaenas, Mytilusgalloprovincialis, and Nereisdiversicolor) and three phytoplankton species (Dunaliellamarina, Prorocentrummicans and Asterionellajaponica) were studied. In general the phytoplankton were found to be more sensitive than the benthic organisms used in our experiments. Considering the results from LC50 (9 days) experiments, the organisms, can be classified in the following decreasing order of sensitivity: D. marina (0.5 ppm), A. japonica (2 ppm), P. micans (3 ppm), N. diversicolor (10 ppm), C. maenas (35 ppm), M. galloprovincialis (65 ppm).  相似文献   

5.
We have studied the acute toxicity of fluoride ion to Gasterosteus aculeatus, Pimephales promelas, and juvenile Salmo gairdneri. LC50 values varied with species and (due to precipitation) initial water hardness. Exposure to elevated fluoride levels in water resulted in increased blood fluoride levels in Salmo gairdneri.  相似文献   

6.
A mixture of ten metals (As, Cd, Cr, Cu, Fe, Pb, Hg, Ni, Se and Zn) at the Great Lakes Water Quality Objective levels was found to reduce the primary productivity of four cultured freshwater algae (Scenedesmus, Chlorella, Anabaena and Navicula) as well as natural phytoplankton from Lake Ontario water. The metal mixture also caused a reduction in the reproduction and transport of an amino acid analogue (α-aminoisobutyric acid) by Ankistrodesmus. The depuration and exchange of the amino acid analogue were not affected by the metal mixture. The nitrogenase activity of Anabaena was, however, reduced in the presence of the metal mixture.  相似文献   

7.
The growth of Anabaenainaequalis was significantly inhibited by Cd2+ concentrations greater than 0.02 ppm (μg/ml) and completely inhibited at 0.06 ppm (Day 12). Cadmium had no significant effect upon the lag phase of growth or the culture doubling time, but caused the retardation phase to arrive sooner. One ppm Cd2+ significantly inhibited the rates of both photosynthesis and acetylene reduction, by A. inaequalis, with complete inhibition at 4 and 20 ppm respectively. Cell sensitivity increased directly with exposure time. Cadmium caused some cell lysis of A. inaequalis and induced an increase in filament length, heterocyst frequency, and a loss of cellular contents from filament apical cells. The cellular abnormalities observed and the fact that toxicity increased with longer exposure times, suggested that metal toxicity resulted from effects of Cd2+ taken up by cells rather than Cd2+ at the cell surface.  相似文献   

8.
Daniel Barug 《Chemosphere》1981,10(10):1145-1154
The degradation of the biocide bis (tributyltin) oxide by pur cultures of microorganisms has been studied. Attempts to isolate microorganisms able to utilize bis (tributyltin) oxide as sole carbon source, were unsuccessful. Of many bacterial species investigated Pseudomonas aeruginosa and Alcaligenes faecalis degraded sublethal amounts of bis (tributyltin) oxide during aerobic growth in the presence of suitable carbon sources. P. aeruginosa converted bis (tributyltin) oxide into monobutyltin and small amounts of dibutyltin derivatives. Similar results were obtained with growing mycelium of Coniophora puteana, Trametes versicolor and Chaetomium globosum. Microbial conversion of monobutyltin trichloride was not observed. Dibutyltin dichloride was converted into monobutyltin derivatives under certain sterile conditions.  相似文献   

9.
Population of microorganisms able to degrade 2,4-D (2,4-dichlorophenoxyacetate) were estimated in 4 non-rhizosphere and 5 rhizosphere soils in Natal by a most probable number (MPN) method using 2,4-D-bromocresol purple media to show 2,4-D degradation with the formation of HC1. Confirmation of herbicide degradation in acid 2,4-D tubes was required by subculturing into fresh 2,4-D-and control indicator media. The MPN estimates of 2,4-D-degrading organisms per g of corresponding rhizosphere/control soils were 6100/212 with African clover (Trifolium africanum L.) soils, and 46400178, 1560001480 and 407006170 with sugarcane (Saccharum officinarum L.) soils. The high, stimulated populations of 2,4-D-degrading microorganisms in the sugarcane rhizospheres suggest the possibility of rapid degradaton in the rhizosphere as an additional mechanism for the protection of certain plants against soil-applied herbicides.  相似文献   

10.
Experiments were conducted to determine the factors responsible for the loss (adsorption, chemical hydrolysis, microbial degradation, etc.) of dichlorvos (2,2-dichlorovingl 0,0-dimethyl phosphate) in soil perfusion systems of Houston Black clay. The rate of disappearance from the perfusate (hence the rate of dichlorvos degradation in soil) was related directly to the presence of Bacilluscereus in the perfusion system, the pH of the system, and the extent of dichlorvos adsorption. Gas liquid chromatographic analyses of the perfusates showed that dichlorvos disappearance was rapid when B. cereus was added to a previously sterilized soil perfusion system (50% in 3.9 days). Under sterile conditions, 50% of the added dichlorvos was recovered after 10 days. When B. cereus was added to a mineral salts medium containing dichlorvos as sole ccrbon source, 49% of the initial dichlorvos concentration was degraded in 4 days. The organism was not capable of utilizing dichlorvos as a sole phosphorus source. Chemical hydrolysis of dichlorvos in aqueous, buffered, soil-free systems showed that hydrolysis did not occur in very acid systems (<pH 3.3), but increased with increasing pH values (26% in 4 days at pH 6.9), and was rapid at pH 9.3 (> 99% in 2 days). The extent of dichlorvos adsorption was determined by comparing the initial loss of dichlorvos in a sterile, soil-free extract solution with the initial loss in a sterile soil perfusion system. The rapid initial disappearance of dichlorvos in the presence of sterilized soil was attributed to soil adsorption of the pesticide. After 10 days both systems contained equal concentrations (50%) of dichlorvos. Non-biological mechanisms accounted for 70% of the total degradation of dichlorvos, while bacterial degradation accounted for 30% in the soil perfusion systems.  相似文献   

11.
The effect of cadmium and of zinc on the rate of uptake of a pentose sugar xylose and an aminoacid tryptophan by the intestine of a teleost fish, Heteropneustesfossilis was studied under two experimental conditions. In the first, four concentrations of cadmium or zinc (1.0 mM, 0.1 mM, 0.01 mM and 0.001 mM) mixed with the nutrient solution were filled in the intestinal sacs, and the rate of absorption was recorded after 1 h at 23°C. In the second experiment fish were exposed by bath to a sublethal concentration of cadmium (0.26 mg/1) or zinc (4 mg/1) for 15 and 30 days and the rate of absorption of the two nutrients was measured. The activity of intestinal Na+, K+ activated adenosine triphosphatase was also assayed. The two heavy metals at all the four concentrations decreased the rate of intestinal transport of nutrients. Increase in the concentration of each of the heavy metals decreased the uptake of nutrients, but the decreases were not linear. The rate of intestinal absorption of the two nutrients was also reduced by exposure of fish to the heavy metals invivo. The activity of Na+, K+ ATPase decreased invitro with all four concentrations of cadmium and zinc and was diminished in fish exposed for 15 and 30 days. Of the two heavy metals, cadmium was more effective in reducing the rate of transport of xylose and tryptophan.  相似文献   

12.
A Wolf  K Bunzl  F Dietl  W.F Schmidt 《Chemosphere》1977,6(5):207-213
Distribution coefficients for the sorption of Pb2+, Cu2+, Cd2+ and Zn2+ by peat were determined as a function of the Ca2+-content of peat as well as of the Ca2+-concentration in the solution. The amount of heavy metal ions taken up was measured for Cu2+, Cd2+ and Zn2+ by atomic absorption spectrometry and for Pb2+ by using Pb-212 as a radioactive tracer.The results show that the distribution coefficients of the heavy metal ions increase, if one increases the initial ratio of the Ca2+H+-ions in the peat phase. The distribution coefficients for the heavy metal ions decrease, however, if - at constant initial Ca2+-content of the peat - the Ca2+-concentration of the solution is increased.  相似文献   

13.
14.
Euphorbia lathyris L., was treated for 24 h. with 0.1, 1 and 10 ppm chlortoluron. The induction kinetic of the fluorescence on the whole leaf was registered during the following 15 days. A recovery of E. lathyris seedlings and an accumulation of chlortoluron in leaves was observed. The fluorescence levels obtained on the leaves emerged after the treatments were similar to the one observed on the control plants. This explains the detoxification mechanism as an accumulation of chlortoluron in the leaves present during the treatment.  相似文献   

15.
The kinetics of oxidation of methylhydrazine (MMH) and 1,1-dimethylhydrazine (UDMH) by dissolved oxygen in water has been measured at various acidities as a function of catalyst (cupric ion) concentration. In dilute solutions the oxidation occurs through a cupric ion catalyzed process as well as by an uncatalyzed step. The extent of formation of nitrosodimethylamine (NDMA) depends upon the initial UDMH concentration. In dilute solutions NDMA is not formed, but in more concentrated solutions, NDMA formation increases with increasing UDMH content, reaches a maximum at 60–80% UDMH (by volume) and then decreases. The NDMA yield appears to approximately parallel the viscosity of the medium, and it is speculated that the factors which control viscosity may also be responsible for governing NDMA formation.  相似文献   

16.
A single intraperitoneal administration of tin (II) tartrate to albino rats (2 mg Sn++100 g body wt) depressed the levels of hepatic glutathione reductase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase, succinic dehydrogenase, reduced glutathione (GSH) and total sulfhydryl contents and led to an elevated level of tin. Serum aminotransferase levels were however, not affected but an increase in serum bilirubin and calcium levels was noticed.Invitro studies showed that tin tartrate upto a concentration of 2 uM did not affect the activity of liver enzymes tested, when the enzyme preparations were incubated with metallic salts during the time of assay. The critical concentration of tin for these parameters was at 5 uM.  相似文献   

17.
Killifish (Fundulussimilis) were exposed in the laboratory to pentachlorophenol (PCP) at concentrations of 57 to 610 μg PCP/L. Bioaccumulation reached a plateau value of about 53 by 168 hrs and remained at this level for at least 72 hrs. One-half the plateau value was reached in about 25 hrs. Following exposure, fish placed in PCP-free aquaria lost PCP rather slowly (t12 ~ 4.7 days). The depuration data were suggestive of a pool of PCP which was lost more rapidly (t12 ~ 4.2 hrs). The results of this study are compared to similar studies in other species. The bioaccumulation factors measured in this study agree relatively well with those in other marine species, but are lower than reported for fresh water species. Possible reasons for this difference are discussed.  相似文献   

18.
H. Barlas  D. Kotzias  H. Parlar 《Chemosphere》1985,14(9):1231-1238
Photochemical reactions of nitrogendioxide and indane 1 were investigated in homogeneous phase with wavelengths above 290 nm. Nitro- and hydroxyindanes were isolated as the principal transformation products. The resulting photoproducts 2 - 9 could be identified by spectroscopical methods such as 1H-NMR, UV, IR and MS.  相似文献   

19.
A new way of detecting trace elements in water is developed by using charged Particle Induced X-ray Emission (PIXE) analysis of cell walls of Chara corallina, a fresh water alga.  相似文献   

20.
Biofiltration is cost-effective for the treatment of gases containing low concentrations of volatile organic compounds (<3gm−3). However, conventional biofilters, based on compost and bacterial activity, face problems with the elimination of hydrophobic compounds. Besides that, biofilter operational stability is often hampered by acidification and drying out of the filter bed. To overcome these problems, biofilters with fungi on inert packing material have been developed. Fungi are more resistant to acid and dry conditions than bacteria, and it is hypothesised that the aerial mycelia of fungi, which are in direct contact with the gas, can take up hydrophobic compounds faster than flat aqueous bacterial biofilm surfaces. Alpha-pinene was chosen as a model compound. It is an odorous compound emitted by the wood processing industry. In 2l biofilter columns four different packing materials were tested: perlite, expanded clay granules, polyurethane foam cubes and compost. The filters were inoculated with forest soil and ventilated with gas containing alpha-pinene. Start up took 1–2 months and removal efficiencies of more than 90% were observed, but mostly ranged from 50% to 90% due to overloading. In the filters containing perlite, clay, polyurethane and compost volumetric removal capacities of, respectively, 24, 33, 38 and 24g alpha-pinenem−3 filter bedh−1 were attained and the gas pressure drops in the 60cm high filter beds measured at a superficial gas velocity of 35mh−1 were 70, 550, 180 and 250Pa. The results indicate that it is possible to develop biofilters based on the action of fungi with higher elimination capacities for alpha-pinene as reported in literature for bacterial biofilters. The use of polyurethane foam cubes is preferred because of the low gas pressure drop in combination with a high volumetric elimination capacity.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号