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941.
Estimation of waste generation from floods 总被引:1,自引:0,他引:1
A framework of correlation for estimating the amount of waste generation from floods is developed. Flood waste data were collected from four recent typhoons in Taiwan. Parameters affecting the flood waste are analyzed. Population density, flooded area and amount of total rainfall are chosen as the correlating parameters for the model development, and regression diagnostics are performed to check the validity of the collected data. The simple linear model is shown to be incapable of correlating the flood waste data. An exponential model is proposed and shown to give acceptable correlation with the flood waste data spanning five orders of magnitude. The model can be useful in the planning of waste cleanup after floods. 相似文献
942.
Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China 总被引:37,自引:0,他引:37
We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products. 相似文献
943.
Polycyclic musks [cashmeran (DPMI), celestolide (ADBI), phantolide (AHMI), traseolide (ATII), tonalide (AHTN) and galaxolide (HHCB)] in the air, wastewater, sludge samples of a typical cosmetic plant were analyzed. DPMI, ADBI, HHCB and AHTN were found in all samples, and ATII was not found in any sample. HHCB and AHTN were the major components in all samples. The polycyclic musk concentrations were very high in the air of the cosmetic plant, and polycyclic musks were mostly contained in the gas phase at the percentage of 86.35-97.70%. Average polycyclic musk concentrations in effluent were high, and ranged from 0.62 to 32.06 microgl-1. The removal efficiency during the active sludge wastewater treatment was also high, resulting from the adsorption of those compounds into the sludge. So the polycyclic musk concentrations were very high in the primary sludge and second sludge, and ranged from 1.78 to 92.45 mgkg-1 (dry), and from 2.87 to 65.67 mgkg-1 (dry), respectively. Results suggested that the sludge needed to be further treated to make polycyclic musks less influence to the environment. 相似文献
944.
The sorption and desorption behavior of benzidine in eight solvent-sediment systems were studied using a batch method. The solvents tested included deionized water (DI), calcium chloride solution (CaCl2), sodium hydroxide solution (NaOH), acetonitrile (ACN), a mixture of acetonitrile and ammonium acetate solution (ACN-NH4OAc), methanol (MeOH), ammonium acetate solution (NH4OAc) and hydrochloric acid solution (HCl). Three sets of sorption isotherm experiments were conducted separately in these eight solvents with seven days, three weeks, and two months of contact times, respectively. The results demonstrated nonlinear benzidine sorption phenomena in all eight solvents with higher sorption affinities for sediment sites in the aqueous solvents than in the organic solvents. The results from the desorption experiments revealed that the benzidine desorption efficiencies in the solvents decreased in an order, which was approximately the reverse order of its sorption affinity. Results also suggested that hydrophobic partitioning and covalent binding processes dominated in the desorption experiments, while cation exchange process had little effect on desorption of benzidine. A three-stage model was subsequently applied to simulate the desorption data in the selected solvents of ACN, ACN-NH4OAc and NaOH, respectively. The rapidly desorbing initial fractions were about 0.13-0.20, 0.15-0.26, and 0.18-0.25 for ACN, ACN-NH4OAc and NaOH, respectively. Finally, the sorbed concentrations of benzidine in slowly and very slowly desorbing domains in the selected solvents were correlated with the maximum sorption capacities obtained from the Langmuir sorption isotherm model. The maximum sorption capacities of benzidine were found to be comparable to the amount of benzidine residing in the slowly and very slowly desorbing domains. 相似文献
945.
Due to the growing concern of highly contaminated landfill leachate problems in Taiwan, an innovative advanced catalytic oxidation (FeGAC/H(2)O(2)) process was developed and employed in this research to treat the landfill leachate from central Taiwan. Experimental results indicated that the FeGAC/H(2)O(2) process could effectively remove organic compounds from landfill leachate. The presence of iron oxide coated granular activated carbon (FeGAC) greatly improved the oxidative ability of H(2)O(2) for the removal of humic acids, fulvic acids and non-humic substance from leachate. For instance, at pH 6, the removal efficiencies of FeGAC/H(2)O(2) and H(2)O(2) processes were 70% and 8%, respectively. FeGAC/H(2)O(2) combined both advantages of FeGAC and H(2)O(2) where FeGAC had good organics adsorption ability and could effectively catalyse the hydrogen peroxide oxidation reaction for organics removal. 相似文献
946.
Evaluation of nitrification inhibitor 3,4-dimethyl pyrazole phosphate on nitrogen leaching in undisturbed soil columns 总被引:3,自引:0,他引:3
The application of nitrogen fertilizers leads to various ecological problems such as nitrate leaching. The use of nitrification inhibitors (NI) as nitrate leaching retardants is a proposal that has been suggested for inclusion in regulations in many countries. In this study, the efficacy of the new NI, 3,4-dimethyl pyrazole phosphate (DMPP), was tested under simulated high-risk leaching situations in two types of undisturbed soil columns. The results showed that the accumulative leaching losses of soil nitrate under treatment of urea with 1.0% DMPP, from columns of silt loam soil and heavy clay soil, were 66.8% and 69.5% lower than those soil columns tested with regular urea application within the 60 days observation, respectively. However, the losses of ammonium leaching were reversely increased 9.7% and 6.7% under the former treatment than the latter one. Application of regular urea with 1.0% DMPP addition can reduce about 59.3%-63.1% of total losses of inorganic nitrogen via leaching. The application of DMPP to urea had stimulated the inhibition effects of DMPP on the ammonium nitrification process in the soil up to 60 days. It is proposed that the DMPP could be used as an effective NI to control inorganic N leaching losses, minimizing the risk of nitrate pollution in shallow groundwater. 相似文献
947.
A fluidized zero valent iron (ZVI) reactor pressurized by CO(2) gas for controlling pH was employed for nitrate reduction. The proposed CO(2) pressurized system potentially has advantages of using less CO(2) gas and reaching equilibrium pH faster than CO(2)-bubbled system. However, due to weak acid nature of carbonic acid, system pH gradually increased with increasing oxidation of ZVI and reduction of nitrate. As pH increased with progress of reaction, nitrate removal rate decreased continuously. The results indicate that nitrate removal efficiency increases with increasing initial ZVI dosage but reaches plateau at ZVI doses of higher than 8.25gl(-1), and initial nitrate concentration up to 100mg l(-1) as N has minimal impact on the removal efficiency. Unlike the fluidized system with pH control by strong acid reported in our pervious study, near 100% of nitrogen recovery was observed in the current process, indicating that nitrate reduction by ZVI with different pH controlled mechanisms will have different reaction routes. 相似文献
948.
Dechlorination of octachlorodibenzo-p-dioxin (OCDD) was carried out in ethanol-water (v/v=1:1) solution of NaOH in the presence of Pd/C catalysts with the use of H(2). The substrate was dechlorinated with Pd/C under mild conditions (atmospheric pressure and <100 degrees C) to give a chlorine-free product, dibenzo-p-dioxin (DD), in high yields. After reaction of 3h at 50 degrees C, 95.9% OCDD was degraded to low dechlorinated congeners and the yield of DD was 77.4%. We have also studied the dechlorination selectivity of chlorine atoms on the different substituted positions and postulated the dechlorination pathway of OCDD. For OCDD, the 2-position has higher reactivity than 1-position, but the difference is very small. From the distribution statistics of the intermediates during the reaction, we postulate that the steric effect plays an important role during the reaction and affect the dechlorination pathway of OCDD. 相似文献
949.
Influence of the DMPP (3,4-dimethyl pyrazole phosphate) on nitrogen transformation and leaching in multi-layer soil columns 总被引:2,自引:0,他引:2
The application of nitrogen fertilizers leads to various ecological problems such as nitrate leaching. The use of nitrification inhibitors as nitrate leaching retardants is a proposal that has been suggested for inclusion in regulations in many countries. In this study, using a multi-layer soil column device, the influence of new nitrification inhibitor DMPP (3,4-dimethyl pyrazole phosphate) was studied for understanding the nitrogen vertical transformation and lowering the nitrate leaching at different soil profile depths. The results indicated that, within 60 d of experiment, the regular urea added 1.0% DMPP can effectively inhibit the ammonium oxidation in the soil, and improve the ammonium concentration in soil solution over the 20cm depths of soil profile, while decline the concentrations of nitrate and nitrite. No obvious difference was found on ammonium concentrations in soil solution collected from deep profile under 20cm depths between regular urea and the urea added 1.0% DMPP. There was also no significant difference for the nitrate, ammonium and nitrite concentrations in the soil solution under 40cm depths of soil profile with the increasing nitrogen application level, among the treatments of urea added 1.0% DMPP within 60 d. It is proposed that DMPP could be used as an effective nitrification inhibitor in some region to control ammonium oxidation and decline the ion-nitrogen leaching, minimizing the shallow groundwater pollution risk and being beneficial for the ecological environment. 相似文献
950.
Mechanism of decolorization and degradation of CI Direct Red 23 by ozonation combined with sonolysis
The decolorization and degradation of CI Direct Red 23, which is suspected to be carcinogenic, were investigated using ozonation combined with sonolysis. The results showed that the combination of ozonation and sonolysis was a highly effective way to remove color from waste water. The operational parameters, namely concentration of the dye, pH, ozone dose and ultrasonic density, were investigated during the process. The decolorization of the dye followed pseudo-first-order kinetics. Increasing the initial concentration of Direct Red 23 led to a decreasing rate constant. The optimum pH for the reaction was 8.0, and both lower and higher pH decreased the removal rate. The effect of the ozone dose on the dye decolorization was much greater than that of the sonolysis density. Intermediates such as naphthalene-2-sulfonic acid, 1-naphthol, urea and acetamide were detected by gas chromatography coupled with mass spectrometry in the absence of pH buffer, while nitrate and sulfate ions and formic, acetic and oxalic acids were detected by ion chromatography. A tentative degradation pathway was proposed without any further quantitative analyses. During the degradation, all nitrogen atoms and phenyl groups of Direct Red 23 were degraded into urea, nitrate ion, nitrogen and formic, acetic and oxalic acids, etc. 相似文献