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11.
Huagang Huang Tingqiang Li D. K. Gupt Zhenli He Xiao-e Yang Bingnan Ni Mao Li 《环境科学学报(英文版)》2012,24(3):376-386
Improving the efficacy of phytoextraction is critical for its successful application in metal contaminated soils. Mineral nutrition affects plant growth and metal absorption and subsequently the accumulation of heavy metal through hyper-accumulator plants. This study assessed the effects of di-hydrogen phosphates (KH2PO4, Ca(H2PO4)2, NaH2PO4 and NH4H2PO4) application at three levels (22, 88 and 352 mg P/kg soil) on Sedum alfredii growth and metal uptake by three consecutive harvests on aged and Zn/Cd combined contaminated paddy soil. The addition of phosphates (P) significantly increased the amount of Zn taken up by S. alfredii due to increased shoot Zn concentration and dry matter yield (DMY) (P<0.05). The highest phytoextraction of Zn and Cd was observed in KH2PO4 and NH4H2PO4 treatment at 352 mg P/kg soil. The amount of Zn removed by phytoextraction increased in the order of 1st clipping<2nd clipping<3rd clipping, and for Cd extraction the order was 2nd clipping<1st clipping<3rd clipping. These results indicate that the application of P fertilizers coupled with multiple cuttings can enhance the removal of Zn and Cd from contaminated soils by S. alfredii, thus shortening the time needed for accomplishing remediation goals. 相似文献
12.
Enhanced and irreversible sorption of pesticide pyrimethanil
by soil amended with biochars 总被引:8,自引:0,他引:8
Biochar derived from partial combustion of vegetation is ubiquitous and potentially effective in sequestration of environmental contaminants.Biochars were prepared by burning of red gum(Eucalyptus spp.) woodchips at 450 and 850°C(labeled as BC450 and BC850).These two biochars were found to possess markedly different properties in terms of surface area and porosity.Short-term equilibration tests(24 hr) were conducted to assess the sorption-desorption behavior of pyrimethanil in the soil amended with various amounts of biochar of each type,with a special focus on the desorption behavior of the sorbed pesticide through four times successive desorption by dilution.Sorption coefficient and isotherm nonlinearity of the amended soils progressively increased with the content of biochar in the soil.Biochar BC850 with higher surface area and microporosity showed a stronger effect on the reversibility of sorption pesticide.The soils amended with 5% BC450 and 1% BC850 had nearly the same sorption capacity for pyrimethanil;however,their desorption processes were very different with 13.65% and 1.49% of the sorbed pesticide being released,respectively.This study suggested that biochar in soil could be an important factor for immobilization of a pesticide and thus affecting its environment fate in soil. 相似文献
13.
Efficiency of white lupin in the removal of mercury from contaminated soils: Soil and hydroponic experiments 总被引:1,自引:0,他引:1
Pilar Zornoz Roc′?o Mill′an M. Jos′e Sierr Almudena Seco Elvira Esteban 《环境科学学报(英文版)》2010,22(3):421-427
This study examined the ability of the white lupin to remove mercury (Hg) from a hydroponic system (Hg concentrations 0, 1.25, 2.5, 5 and 10 μmol/L) and from soil in pots and lysimeters (total Hg concentration (19.2 ± 1.9) mg/kg availability 0.07%, and (28.9 ± 0.4) mg/kg availability 0.09%, respectively), and investigated the accumulation and distribution of Hg in different parts of the plant. White lupin roots efficiently took up Hg, but its translocation to the harvestable parts of the plant was low. The Hg concentration in the seeds posed no risk to human health according to the recommendations of the World Health Organization, but the shoots should not be used as fodder for livestock, at least when unmixed with other fodder crops. The accumulation of Hg in the hydroponically-grown plants was linear over the concentration range tested. The amount of Hg retained in the roots, relative to the shoots, was almost constant irrespective of Hg dose (90%). In the soil experiments, Hg accumulation increased with exposure time and was the greater in the lysimeter than in the pot experiments. Although Hg removal was the greater in the hydroponic system, revealing the potential of the white lupin to extract Hg, bioaccumulation was the greatest in the lysimeter-grown plants; the latter system more likely reflects the true behaviour of white lupin in the field when Hg availability is a factor that limits Hg removal. The present results suggest that the white lupin could be used in long-term soil reclamation strategies that include the goal of profitable land use in Hg-polluted areas. 相似文献
14.
This article describes the integrated modeling approach for planning the size and the operation of constructed wetlands for
maximizing retention of nonpoint source pollutant loads and reservoir water-quality improvement at a catchment scale. The
experimental field-scale wetland systems (four sets, 0.88 ha each) have been in operation since 2002, where water depth was maintained
at 30–50 cm and hydraulic loading rate was at 6.3–18.8 cm/day. The wetland system was found to be adequate for treating polluted
stream water with stable removal e ciency even during the winter. The integrated modeling system (modified-BASINS) was applied to
the Seokmoon estuarine reservoir watershed and calibrated with monitoring data from constructed wetland, stream, and reservoir. The
calibrated integrated modeling system estimated that constructing wetlands on 0.5% (about 114 ha) of the watershed area at the mouth
of reservoir could reduce 11.61% and 13.49% of total external nitrogen and phosphorus loads, respectively. It also might improve the
nitrogen and phosphorus concentration of the reservoir by 9.69% and 16.48%, respectively. The study suggested that about 0.1%–1.0%
of the watershed area should be allocated for constructed wetland to meet specified water-quality standards for the estuarine reservoir
at the polder area where land use planning is relatively less complicated. 相似文献
15.
A controlled hydroponic experiment was undertaken to investigate Cd uptake in relation to the activity of Cd species in solution other than the free ion (Cd2+) by maintaining a constant Cd2+ activity under variable SO42− and Cl− concentrations exposed to maize (Zea mays var. Cameron) plants. The objectives of these experiments were: (1) to distinguish and quantify the different uptake rates of free and inorganic-complexed Cd from nutrient solution, and (2) to model the uptake of Cd by maize with a Biotic Ligand Model (BLM) in a system which facilitates the close examination of root characteristics. Results of the current experiments suggest that, in addition to the free ion, CdSO40 complexes are important factors in determining Cd uptake in nutrient solution by maize plants. Higher nominal SO42− concentrations in solution generally resulted in a greater Cd accumulation by maize plants than predicted by the Cd2+ activity. A better integration of the complete dataset for the 3 harvest times (6, 9 and 11 days after treatment) was achieved by including consideration of both the duration of Cd exposure and especially the root surface area to express Cd uptake. Similarly, the fit of the BLM was also improved when taking into account exposure time and expressing uptake in terms of root morphological parameters. 相似文献
16.
Releases of phosphate fertilizer industry in the surrounding environment:
Investigation on heavy metals and polonium-210 in soil 总被引:1,自引:1,他引:0
Distribution of Cu,Zn,Pb,Cr,Ni,Mn concentrations and the activity of polonium-210 in the surrounding area of a phosphate fertilizer industry located on the eastern coast of the Mediterranean Sea has been determined.Nineteen sampling sites were distributed around the industrial zone on a surface area of about 100,000 m2.Atomic absorption spectroscopy and Alpha spectroscopy were used to quantify the heavy elements and polonium-210,respectively.Investigation on a particle scale was conducted by TEM and SEM coupled to EDX and X-ray cartography to determine the nature of heavy elements carriers and their distribution.Heavy elements were mainly concentrated inside the particle size fraction 50 μm.Their levels decreased with distance increasing from the industry.According to the reference soil,enrichment factors were about 10,15,32 and 100 times for Zn,Pb,Cu,and Cr,respectively inside the particle size fraction 50 μm on the closest sites to the industry.The main contaminant sources were transport and storage of row materials and the free release of phosphogypsum waste.Heavy elements were entrapped inside agglomerates of sulfates,phosphates and iron oxihydroxides in a di used shape.Polonium-210 with an enrichment factor of about 56,showed the same behavior of the spatial distribution of the trace elements. 相似文献
17.
Constructed wetland (CW) is the preferred means of controlling water quality because of its natural treatment mechanisms and
function as a secondary or tertiary treatment unit. CW is increasingly applied in Korea for secondary e uent of livestock wastewater
treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil
layer and to reduce the phosphorus release from sediments of the free water surface CW for the treatment of secondary piggery
wastewater e uent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types
at near the inlet of the CW were non-apatite phosphorus (59%) and residual phosphorus (32%) suggesting that most of the particles of
the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term
maintenance requirements over the lifetime of CW. Continuous monitoring will be performed for a further assessment of the CW
system and design. 相似文献
18.
树脂负载Fe3+/Cu2+多相类芬顿降解染料橙黄 总被引:3,自引:1,他引:2
制备了新型多相类Fenton催化剂(Fe3+cu2+)/R(Fe3+和cu2+同时负载于离子交换树脂),以橙黄Ⅳ为研究对象,探讨了初始过氧化氢浓度、橙黄Ⅳ浓度、催化剂量、初始pH值及温度等因素对催化反应速率的影响,并对该催化剂重复使用性能进行测试.研究结果表明,该催化剂(Fe3++Cu2+)/R与Fe3+/R相比表现出更好的催化过氧化氢分解的活性,使橙黄Ⅳ的降解率提高10%;催化过氧化氢氧化橙黄Ⅳ的反应遵循假一级反应动力学,反应活化能为10.71 kJ·mol-1;催化剂表现出良好的重复使用性能,Fe3+和cu2+在树脂表面负载比较牢固,具有较好的稳定性和耐用性.同时,电子顺磁共振(EPR)测试结果表明,cu2+的掺杂能有效地促进OH·的产生;X射线光电子能谱(XPS)测试结果表明,反应过程中存在高价态铁物种.因此,在该体系反应过程中产生的活性物种是OH·和高价态铁同时共存. 相似文献
19.
Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful e ects
on human health and other organisms in the environment. Most of the studies dealing with toxic e ects of metals deal with single
metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting
the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the
bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in
binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also
the “critical” organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher
than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher
than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation
for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C.
mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats. 相似文献
20.
In this study, chlorine decay experiments were conducted for the raw water from Nakdong River that is treated by Chilseo Water
Treatment Plant (CWTP) situated in Haman, Korea as well as the e uents from sand and granular activated carbon (GAC) filters of
CWTP and fitted using a chlorine decay model. The model estimated the fast and slow reacting nitrogenous as well as organic/inorganic
compounds that were present in the water. It was found that the chlorine demand due to fast and slow reacting (FRA and SRA)
organic/inorganic substances was not reduced significantly by sand as well as GAC filters. However, the treated e uents from those
filters contained FRA and SRA that are less reactive and had small reaction rate constants. For the e uents from microfiltration,
ultrafiltration, and nanofiltration the chlorine demand because FRA and SRA were further reduced but the reaction rate constants were
larger compared to those of sand and GAC filter e uents. This has implications in the formation of disinfection by products (DBPs).
If DBPs are assumed to form due to the interactions between chlorine and SRA, then it is possible that the DBP formation potential in
the e uents from membrane filtrations could be higher than that in the e uents from granular media filters. 相似文献