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1.
Among the many larvicides tested for the control of s.l. larvae, the vector of human onchocerciasis in West Africa, pyraclofos proved to be 100% effective at 100 μg × L−1 for 10 min in river, with a carry of 20 km at 100 m3 × sec−1. Tests were then performed both in laboratory and field conditions to evaluate its toxicity on the non-target aquatic fauna. In experimental short-term gutter tests, the detachment of the total benthic insects was 35% at 100 μg × L−1 for 10 min against 17% for temephos at the same dose and 59% for chlorphoxim at 50μg × L−1 for 10 min. , and were the most affected organisms. The treatment of a river resulted in a considerable detachment of the same taxonomic groups, plus Orthocladiinae. On the other hand, investigations conducted in tanks showed that the 24-hr LC50 for is 150 μg × L−1 and that for 170 μg × L−1, values which are not very different from the operational dose of the larvicide (100 μg × L−1 for 10 min.). Nevertheless, in a river, no fish mortality was recorded. Based on fish LC50 and drift of benthic insects, pyraclofos at 100 μg × L−1 was judged to be less toxic to aquatic fauna in the short term than permethrin and carbosulfan.  相似文献   

2.
Hayla E. Evans 《Chemosphere》1988,17(12):2325-2338
The binding of three polychlorinated biphenyl (PCB) congeners to natural levels of dissolved organic carbon (DOC) was measured in 12 lakes and streams using Sep-Pak C18 columns. The association coefficients calculated on the basis of DOC (i.e. KDOC mL/g C), varied by over an order of magnitude among the different freshwaters and ranged between 2.05 × 102 and 8.86 × 103 mL/g C for PCB 52 and 1.03 × 104 and 1.70 × 105 mL/g C for PCB 153. In general, there were no significant correlations (p > 0.05) between the KDOC values and various chemical parameters in the study lakes and streams.

A relationship was derived between the fraction of bound PCB and the octanol-water partition coefficient. While this relationship explained almost 50% of the variation in the observed data, it is apparent that other factors influence KDOC values and that in natural freshwaters, only a small fraction of the DOC is involved in the binding of PCBs and other hydrophobic pollutants.  相似文献   


3.
Maaret Kulovaara 《Chemosphere》1993,27(12):2333-2340
DDT and benzo[a]pyrene (BaP) were added both separately and as a mixture to filtered (0.22 μm) humic surface water samples. Following a contact time of 1 d, the fraction bound to dissolved organic matter and the freely dissolved part were separated by using reversed-phase octadecyl silica cartridges. The enriched solutes were analysed by gas chromatography-mass spectrometry in the selective ion monitoring (GC-MS/SIM) mode. Partition coefficients to dissolved organic matter, calculated on the basis of the recovery data, varied between 2.0 × 104 and 6.6 × 104 mL/g for BaP depending on the experimental conditions, whereas the corresponding values for DDT (0.6 × 104 mL/g) showed no significant variation.  相似文献   

4.
Neamtu M  Siminiceanu I  Kettrup A 《Chemosphere》2000,40(12):1407-1410
The photodegradation of five representative nitromusk compounds in water has been performed in a stirred batch photoreactor with a UV low-pressure immersed mercury lamp, at constant temperature and different doses of hydrogen peroxide. The rate constants have been calculated on the basis of experimental data and a postulated first-order kinetic model. The rate constants, at 298 K and a dose of 1.1746 μmol l−1 H2O2 ranges from 0.3567 × 10−3 s−1 for musk tibetene, to 1.785 × 10−3 s−1 for musk ambrette.  相似文献   

5.
Doong RA  Chang SM 《Chemosphere》2000,40(12):1427-1433
An investigation involving the supplement of different concentrations of substrates and microorganisms was carried out under anaerobic condition to assess the feasibility of bioremediation of carbon tetrachloride (CCl4) with the amendment of low concentrations of auxiliary substrate and microorganisms. The concentrations of substrate and microorganisms ranged from 10 to 100 mg/l and from 3.7 × 104 to 3.7 × 106 cell/ml, respectively. The biotransformation rate of CCl4 increased progressively with the increase in the concentrations of the substrate and microorganisms. In the low biomass-amended system (3.7 × 104cells/ml), 28–71% and 57–96% of CCl4 removals were exhibited when 10–100 mg/l of acetate or glucose was supplemented, respectively, whereas nearly complete degradation of CCl4 was observed in the heavily inoculated systems (3.7 × 106 cells/ml). An addition of electron donor in the low microbial activity batches enhanced greater efficiency in dechlorination than in the high microbial activity batches. The second-order rate constants ranged from 0.0059 to 0.0092 l/mg/day in high biomass input system, while a two- to four-fold increase in rate constant was obtained in the low microbial activity system. This study indicates that biomass was the more important environmental parameter than substrate affecting the fate of CCl4. The addition of auxiliary substrates was effective only in low biomass-amended batches (0.56 mg-VSS/l) and diminished inversely with the increase of microbial concentration.  相似文献   

6.
Kang YS  Yamamuro M  Masunaga S  Nakanishi J 《Chemosphere》2002,46(9-10):1373-1382
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/DFs) were detected in waterfowl such as common cormorants, tufted ducks, and their prey, namely fish and bivalves from Lake Shinji, Japan. The concentration of total PCDDs/DFs-TEQ was found to be higher in the muscle tissues of common cormorants than in those of tufted ducks. The results of hierarchical cluster analysis implied that the residue distribution pattern of PCDD/DF homologues was considerably different between these two species. Furthermore, biomagnification factors (BMFs) were estimated from bivalves as prey to tufted duck muscles as target organs. Despite the highest concentrations of 1,3,6,8- and 1,3,7,9-TeCDD in tufted ducks and their prey, however, the BMFs of these isomers were calculated to be lower than those of the toxic 2,3,7,8-substituted PCDDs/DFs. On the other hand, log BMF of toxic 2,3,7,8-substituted PCDDs/DFs were significantly higher for lower chlorinated isomers than those of the higher chlorinated isomers. The biota-sediment accumulation factors (BSAFs) of PCDDs/DFs were also estimated using shijimi clam and fish samples against sediment from Lake Shinji. The average BSAFs were estimated and ranged from 4.0×10−3 to 2.2×10−1 and 2.0×10−4 to 2.0×10−1 for bivalve and fish samples, respectively. Based on calculated BMFs and BSAFs, the total PCDD/DF-TEQ levels in the tufted duck were estimated to have been lowest (2.0 pg TEQ/g dry weight basis) in 1947 and highest (9.8 pg TEQ/g) in 1971.  相似文献   

7.
Uchida S  Tagami K  Rühm W  Wirth E 《Chemosphere》1999,39(15):2757-2766
Technetium-99 was determined in samples from the 30-km zone around the Chernobyl reactor. Concentrations of 99Tc in soil samples taken from three forest sites ranged from 1.1 to 14.1 Bq kg−1 dry weight for the organic soil layers, and from 0.13 to 0.83 Bq kg−1 dry weight for the mineral soil layers. In particular, for the organic layers, the measured 99Tc concentrations were one or two orders of magnitude higher than those due to global fallout 99Tc. The 99Tc depositions (Bq m−2), based on the sum of the depositions measured in organic and mineral layers, ranged from 130 Bq m−2 within the 10-km zone to about 20 Bq m−2 close to the border of the 30-km zone. Taking the corresponding measured 137Cs depositions into account, it was found that the activity ratio of 99TW/137Cs ranged from 6 × 10−5 to 1.2 × 10−4. It was estimated that about 970 GBq of 99Tc had been released by the Chernobyl accident. This figure corresponded to 2%–3% of the total 99Tc inventory in the core.  相似文献   

8.
Delphin JE  Chapot JY 《Chemosphere》2006,64(11):1862-1869
A field experiment was conducted on a Calcaric Cambisol soil to study the consequences of the penetration depth and properties of pesticides on the risk of subsequent leaching. Three pesticides with different mobility characteristics and bromide were injected at 30 cm (where soil organic matter (OM) was 2%) and 80 cm (soil OM 0.5%) on irrigated plots without a crop. The migration of injected solutes was assessed for two years by sampling the soil solution using six porous cups installed at 50 and 150 cm depth and by relating solute contents to drainage water flux estimated by the STICS model (Simulateur mulTIdisciplinaire pour les Cultures Standard). Pesticides injected at 30 cm were strongly retained so that no metolachlor or diuron was detected at 50 and 150 cm. The ratio of atrazine peak concentration in the soil solution to concentration in the injected solution (C/C0) was 1 × 10−3 and 0.2 × 10−3, respectively, at 50 and 150 cm. When injected at 80 cm, (C/C0) of atrazine, metolachlor and diuron were 10 × 10−3, 1 × 10−3 and 0.3 × 10−3 at 150 cm, respectively; 1/(C/C0) was correlated with Koc values reported from databases. The ratio of drainage volume to the amount of water at field capacity in the soil layer between the injection point at 30 cm and the water sampling level (V/V0) at 50 and 150 cm was 0.6 and 0.9, respectively, for bromide and 1.6 and 1.0 for atrazine. V/V0 of the injected solutes at 80 cm was for bromide, atrazine, metolachlor and diuron 0.6, 0.9, 1.2 and 1.7, respectively; pesticide V/V0 was correlated with Koc. The retardation factor was a good indicator of migration risk, but tended to overestimate retardation of molecules with high Koc. Atrazine desorption represented an additional leaching risk as a source of prolonged low contamination. The large variability in soil solution of bromide and pesticide concentrations in the horizontal plane was attributed to flow paths and clods in the tilled soil layer. This heterogeneity was assumed to channel water fluxes into restricted areas and thereby increase the risk of groundwater contamination. The methodology used in the field proves to provide consistent results.  相似文献   

9.
Determination of triazines herbicides (atrazine and simazine) by high performance liquid chromatography (HPLC) in samples of trophic chain were worked out. Determination limits of 0.5 μg g−1 for atrazine, 0.8 μg g−1 for simazine with pesticides recovery of 70–77% in trophic chain samples were obtained. The content of simazine in soils was in range 1.72–57.89 μg g−1, in grass 5–88 μg g−1, in milk 2.32–15.29 μg g−1, in cereals 10.98–387 μg g−1, in eggs 30.14–59.48 μg g−1, for fruits: 2.45–6.19 μg g−1. The content of atrazine in soils was in range 0.69–19.59 μg g−1, in grass 7.85–23.85 μg g−1, in cereals 1.88–43.08 μg g−1. Cadmium, lead and zinc were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in the same samples as atrazine and simazine. Determination limits for cadmium 5 × 10−3 μg g−1, for lead 1 × 10−2 μg g−1, and for zinc 0.2 × 10−3 μg g−1, were obtained. The content of cadmium in soil was in range 0.13–5.89 μg g−1, in grass 114–627.72 × 10−3 μg g−1, in milk 8.88–61.88 × 10−3 μg g−1, in cereals 0.20–0.31 μg g−1, in eggs 0.11–0.15 μg g−1, in fruits 0.23–0.59 μg g−1. The content of lead in soils was in range 0.57–151.50 μg g−1, in grass 0.16–136.57 μg g−1, in milk 1.16–3.74 μg g−1, in cereals 1.05–5.47 μg g−1, in eggs 5.79–55.87 μg g−1, in fruits 21.00–87.36 μg g−1. Zinc content in soil was in range 9.15–424.5 μg g−1, in grass 35.20–55.87 μg g−1, in milk 20.00–34.38 μg g−1, in cereals 14.94–28.78 μg g−1, in eggs 15.67–32.01 μg g−1, in fruits 14.94–18.88 μg g−1.

Described below extraction and mineralization methods for particular trophic chains allowed to determine of atrazine, simazine, cadmium, lead and zinc with good repeatability and precision. Emphasis was focused on liquid–liquid extraction and solid-phase extraction of atrazine and simazine from analysed materials, as well as, on monitoring the content of herbicides and metals in soil and along trophic chain. Higher concentration of pesticides in samples from west region of Poland in comparison to that of east region is likely related to common applying them in Western Europe in relation to East Europe. The content of metals strongly depends on samples origin (industry area, vicinity of motorways).  相似文献   


10.
Tagami K  Uchida S 《Chemosphere》2006,65(11):2358-2365
Concentrations of halogens (Cl, Br and I) in 30 Japanese rivers were measured by ion chromatography and inductively coupled plasma mass spectrometry to understand their behavior in the terrestrial environment. Concentrations of Cl, Br and I in each river, obtained at 10 sampling points from the upper stream to the river mouth, tended to increase near the river mouth. The ranges of geometric means of Cl, Br and I in each river were 1.0–19.4 mg l−1, 2.5–67.9 μg l−1, and 0.18–8.34 μg l−1, respectively. To compare halogen behavior, the concentration ratios, Br/Cl and I/Cl, were calculated. The Br/Cl range was (2.3–7.8) × 10−3 (geometric mean: 3.74 × 10−3), and it was nearly constant except for the Yoneshiro river. It was estimated that 60–80% of total Br in the middle to lower parts of this river was the excess Br. The Br chemical form in all the rivers is generally considered to be Br. The I/Cl ratios had different trends in rivers flowing into the Japan Sea and Pacific Ocean, possibly due to the different geological features in the river catchments.  相似文献   

11.
Eapen S  Singh S  Thorat V  Kaushik CP  Raj K  D'Souza SF 《Chemosphere》2006,65(11):2071-2073
Potential of plants to remove radionuclides/toxic elements from soils and solutions can be successfully applied for removal of important radionuclides such as strontium-90 (90Sr) and cesium-137 (137Cs). When uptake of 137Cs and 90Sr by Calotropis gigantea plants incubated in distilled water spiked with the radionuclides either alone or in combination was studied, it was found to have a high efficiency for the removal of 90Sr, with 90% being removed from solutions (5 × 103 kBq l−1) within 24 h of incubation. However, in case of 137Cs, about 44% could be removed from solutions (5 × 103 kBq l−1) at the end of 168 h of incubation. Accumulation of 90Sr and 137Cs was higher in roots compared to shoots. The plants could remediate both 90Sr and 137Cs when they were added together to the solution. When two months old plants were incubated in low level nuclear waste, 99% of activity disappeared at the end of 15 days. The present study suggests that C. gigantea could be used as a potential candidate plant for phytoremediation of 90Sr and 137Cs.  相似文献   

12.
New data on the vapour pressures and aqueous solubility of 1,8-dichlorooctane and 1,8-dibromooctane are reported as a function of temperature between 20 °C and 80 °C and 1 °C and 40 °C, respectively. For the vapour pressures, a static method was used during the measurements which have an estimated uncertainty between 3% and 5%. The aqueous solubilities were determined using a dynamic saturation column method and the values are accurate to within ±10%. 1,8-Dichlorooctane is more volatile than 1,8-dibromooctane in the temperature range covered (psat varies from 3 to 250 Pa and from 0.53 to 62 Pa, respectively) and is also approximately three times more soluble in water (mole fraction solubilities at 25 °C of 5.95 × 10−7 and 1.92 × 10−7, respectively). A combination of the two sets of data allowed the calculation of the Henry’s law constants and the air water partition coefficients. A simple group contribution concept was used to rationalize the data obtained.  相似文献   

13.
Vitali M  Ensabella F  Stella D  Guidotti M 《Chemosphere》2004,57(11):1637-1647
A sampling campaign for the determination of concentrations of nonylphenol isomers (NPs) in freshwaters and sediments of the hydrologic system of the Rieti district (central Italy) was conducted from 2002 to 2003. Eighteen sampling points, selected on the basis of the different human activities in the vicinity, were monitored; six series of water samples (from June 2002 to February 2003) and one of sediment samples (summer 2002) were analyzed by GC/MS.

There was a direct relationship between concentrations of NPs and the presence of urban or industrial activities near the sampling point. However, concentrations of NPs in water were in the range of <0.1–1.4 μg l−1, and their presence limited to short distances from the sources of contamination. Accumulation factors in sediment samples ranged from 102 to 5 × 103.  相似文献   


14.
The carcinogenicity of 2,3,7,8-TCDD at multiple organ sites in animals has been well established by several cancer bioassays. Results of two of the most notable of these, the Kociba et al. (1978) rat feeding study and the National Toxicology Program (1980) gavage study in rats and mice showed hepatocellular carcinomas in two strains of female rats and male and female mice. Other tumor sites included carcinomas of the lung, tongue, hard palate and nasal turbinates, thyroid, and subcutaneous tissue. The evidence for carcinogenicity of 2,3,7,8-TCDD in animals is regarded as “sufficient” using the classification system of the International Agency for Research on Cancer (IARC).

Two Swedish epidemiologic case-control studies (Hardell and Sandstrom, 1979; Eriksson et al. 1979, 1981) reported a significant five- to sevenfold excess risk of soft-tissue sarcomas (STS) from occupational exposure to chlorinated phenoxyacetic acid herbicides and/or chlorophenols. Additionally, several small cohort studies collectively exhibited an unusual cluster of STS, significantly increased over combined expected incidence. Problems with these studies do not appear to be sufficient to discount this excess risk. The human evidence alone for the carcinogenicity of 2,3,7,8-TCDD is “inadequate” using the IARC classification. However, for 2,3,7,8-TCDD in combination with chlorinated phenoxyacetic acid herbicides and/or chlorophenols, the human evidence is considered to be “limited.” The overall evidence for carcinogenicity considering both animal and human studies would place 2,3,7,8-TCDD alone in the IARC category 2B, meaning that the substance is probably carcinogenic in humans. The overall weight of evidence for 2,3,7,8-TCDD in combination with chlorinated phenoxyacetic acid herbicides and/or chlorophenols is regarded as IARC category 2A, also meaning that they are probably carcinogenic for humans.

Using current EPA methodology for quantitatively estimating cancer risks, several animal data sets have been analyzed. Comparing the results, the upper-limit incremental unit risk estimate is 1.6 × 10−2 for a lifetime exposure of 1 ng/kg/day. This estimate is derived from a lifetime feeding study (Kociba et al., 1978) in which 2,3,7,8-TCDD induced tumors of the liver, lungs, hard palate, and nasal turbinates in female rats. Incremental unit cancer risks are also extrapolated for lifetime 2,3,7,8-TCDD exposures in water and air. Based on continuous lifetime exposure to 1 ng/L 2,3,7,8-TCDD in drinking water, the upper-limit estimate of extra cancer risk per individual is 4.5 × 10−3. For lifetime exposure to 1 pg 2,3,7,8-TCDD/m3 in the ambient air, the upper-limit individual risk is 3.3 × 10−5.  相似文献   


15.
Synchronous-scan fluorescence spectra of Chlorella vulgaris solution   总被引:1,自引:0,他引:1  
Liu X  Tao S  Deng N 《Chemosphere》2005,60(11):1550-1554
The characterization of the Chlorella vulgaris solution was carried out using synchronous-scan spectroscopy. The range of concentration of algae and Fe(III) in aqueous solutions were 5 × 108–8 × 109 cells l−1 and 10–60 μM, respectively. Effective characterization method used was synchronous-scan fluorescence spectroscopy. The wavelength difference (Δλ) of 90 nm was maintained between excitation and emission wavelengths; 90 nm was found to be the best Δλ for effective characterization of Chlorella vulgaris solution with or without quencher species (e.g., Fe(III), humic acid (HA)) for the first time. The peak was observed at about EX 236.6 nm/EM 326.6 nm for synchronous-scan fluorescence spectra. The fluorescence quenching of algae in system of algae–Fe(III)–HA was studied using synchronous-scan spectroscopy for the first time. Fe(III) was clearly the effective quencher. The relationship between I0/I (quenching efficiency) and c (concentration of Fe(III) added) was a linear correlation for the algae solution with Fe(III). Also, Aldrich humic acid was found to be an effective quencher. pH effect on synchronous-scan fluorescence intensity of algal solution with Fe(III) and/or HA was evident.  相似文献   

16.
Kraal P  Jansen B  Nierop KG  Verstraten JM 《Chemosphere》2006,65(11):2193-2198
The speciation of titrated copper in a dissolved tannic acid (TA) solution with an initial concentration of 4 mmol organic carbon (OC)/l was investigated in a nine-step titration experiment (Cu/OC molar ratio = 0.0030–0.0567). We differentiated between soluble and insoluble Cu species by 0.45 μm filtration. Measurements with a copper ion selective electrode (ISE) and diffusive gradients in thin films (DGT) were conducted to quantify unbound Cu(II) cations (‘free’ Cu) and labile soluble Cu complexes. For the DGT measurements, we used an APA hydrogel and a Chelex 100 chelating resin (Na form). Insoluble organic Cu complexes (>0.45 μm) was the dominant Cu species for Cu/OC = 0.0030–0.0567 with a maximum fraction of 0.96 of total Cu. At Cu/OC > 0.0100, Cu-catalysed degradation of aggregate structures resulted in a strong increase of free Cu and (labile) soluble Cu complexes with a maximum fraction of 0.28 and 0.32 of total Cu, respectively. Labile (i.e. DGT-detectable) soluble Cu complexes had a relatively high averaged diffusion coefficient (D) in the APA hydrogel (3.50 × 10−6– 5.58 × 10−6 cm2 s−1).  相似文献   

17.
Liu Y  Yang F  Chen J  Gao L  Chen G 《Chemosphere》2003,50(10):1275-1279
Reductive dechlorination rate constants for five chlorobenzenes in the presence of Pd/Fe as catalyst were determined experimentally. Linear free energy relationships (LFER) for the dechlorination rate constants of five chlorobenzenes and three chlorophenols were developed by partial least squares (PLS) regression based on quantum chemical parameters computed by PM3 Hamiltonian. The optimal LFER model obtained is
logk=−1.63+1.46×10−3ΔHf−7.69×10−1ELUMO
where k stands for the dechlorination rate constants, ΔHf is the standard heat of formation, and ELUMO is the energy of the lowest unoccupied molecular orbital. The Q2cum value of the model is 0.879, indicating good robustness and predictive power of the model.  相似文献   

18.
Sterling RO  Helble JJ 《Chemosphere》2003,51(10):1111-1119
In coal combustion systems, the partitioning of arsenic between the vapor and solid phases is determined by the interaction of arsenic vapors with fly ash compounds under post-combustion conditions. This partitioning is affected by gas–solid reactions between the calcium components of the ash particles and arsenic vapors. In this study, bench scale experiments were conducted with calcium compounds typical of coal-derived fly ash to determine product formation, the extent of reaction and reaction rates when contacted by arsenic oxide vapors. Experiments conducted with arsenic trioxide (As4O6(g)) vapors in contact with calcium oxide, di-calcium silicate and mono-calcium silicate over the temperature range 600–1000 °C indicated that these solids were capable of reacting with arsenic vapor species in both air and nitrogen. Calcium arsenate was the observed reaction product in all the samples analyzed. Maximum capture of arsenic occurred at 1000 °C with calcium oxide being the most effective of the three solids over the range of temperatures studied. Using a shrinking core model for a first order reaction and the results from intrinsic kinetic experiments conducted in air, the reaction rate constants were found to be 1.4×10−3exp(−2776/T) m/s for calcium oxide particles, 7.2×10−3exp(−3367/T) m/s for di-calcium silicate particles and 5.5×10−3exp(−3607/T) m/s for mono-calcium silicate particles. These results therefore suggest that any calcium present in fly ash can react with arsenic vapor and capture the metal in water-insoluble forms of the less hazardous As(V) oxidation state.  相似文献   

19.
K. Kawamoto  K. Urano 《Chemosphere》1989,18(9-10):1987-1996
Octanol-water partition coefficients and air-water partition coefficients of 10 principal organochlorine pesticides were obtained as basic data for predicting their fate in environment. The octanol-water partition coefficients were in the wide range from 10 to 106 and approximately correlated with the solubilities in water. The air-water partition coefficients were also in the wide range from 10−7 to 10−2, and the values for chloropicrin, dichlorvos, DCIP and quintozene were relatively high.  相似文献   

20.
The interaction of Cu with dissolved organic matter (DOM, extracted from an organic forest floor) was investigated and the resulting data was evaluated in terms of their uncertainty. The speciation of Cu over ‘free’ Cu (as analysed by diffusive gradients in thin films (DGT)), dissolved Cu–DOM complexes and precipitated Cu–DOM was determined as a function of pH (3.5, 4.0 and 4.5) and Cu/C ratio. The dissolved organically bound fraction was highest at pH 4.5, but this fraction decreased with increasing Cu/C ratio, which was observed for all pH levels. In the range of Cu/C=7×10−5–2.3×10−2 (mol/mol) the precipitated fraction was very small. The speciation of both Al and Fe was not affected by increasing Cu concentrations. From a continuous distribution model using the Scatchard approach, we calculated the optimal fit and corresponding upper and lower 95% uncertainty bounds of the overall stability constants (Ko) with the shuffled complex evolution Metropolis (SCEM) algorithm. Although the optimal equation fitted the data very well, the uncertainty of the, according to literature, most reliable approach to establish stability constants, was still large. Accordingly, the usually reported intrinsic stability constants exhibited large uncertainty ranging from logKi=6.0–7.1 (optimal 6.7) for pH 3.5, logKi=6.5–7.1 (optimal 6.8) for pH 4.0, and logKi=6.4–7.2 (optimal 6.8) for pH 4.5 and showed only little effect of pH.  相似文献   

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