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991.
Co-transport of dissolved organic matter and heavy metals in soils induced
by excessive phosphorus applications 总被引:2,自引:0,他引:2
To evaluate the e ects of long-term applications of phosphorus fertilizers on mobility of dissolved organic matter (DOM) and heavy
metals in agricultural soils, a sandy soil and a loamy soil were spiked with ammonium phosphate at application rates of 0, 25, 50,
100, 250, and 500 mg P per kilogram of soil. A series of 15-cm long soil columns were constructed by packing incubated soils of
varying concentrations of P. The soil columns were consecutively leached by simulated rainfalls for six cycles. The contents of water
extractable organic carbon in both sandy and loamy soils increased significantly with increasing rates of P applications. Relatively
high rates of P applications could induce a marked increase in DOM concentrations in the leachates, the e ects were larger with the
sandy soil rather than with the loamy soil. Applications of P changed the partitioning of trace metals in the soil solids and the soil
solutions. The increased P application rates also seemed to elevate the leaching of Cu, Cd, and Zn from soils. The concentrations of
Cu, Cd, and Zn in the leachates were positively correlated with DOM, probably due to the formation of metal-DOM complexes. In
contrast, Pb concentrations in the leachates were negatively correlated with DOM, and decreased with increasing rates of P applications.
The boosted leaching of DOM induced by high rates of P applications was probably due to the added phosphate ions competing for
adsorption sites in the soil solids with the indigenous DOM. 相似文献
992.
Liangliang Wei Kun Wang Qingliang Zhao Junqiu Jiang Chunmei Xie Wei Qiu 《环境科学学报(英文版)》2010,22(5):641-647
In order to characterize the organic properties of waste activated sludge in a wastewater treatment plant,organic matter within sludge was extracted with NH 3 ·H 2 O preferentially,and subsequently fractionated into five fractions using XAD-8/XAD-4 resins.Up to a 63.8%-71.1% of organic matter within the sludge could be efficiently extracted by NH 3 ·H 2 O.Fractionation results showed that hydrophobic acid and hydrophilic fraction were two main components among the sludge organic matter (accounting for 32.2% and 48.0% of the bulk organic matter,respectively),whereas transphilic acid,hydrophobic neutral and transphilic neutral were quite low (accounting for 9.2%,5.8% and 4.8%,respectively).Despite that the extractant of NH 3 ·H 2 O showed a relatively higher extraction efficiency of the aromatic components,the relatively low aromaticity of the organic fractions implied that those non-aromatic components could also be effectively extracted,especially for neutral and hydrophilic fractions.In addition,acidic fractions contained more aromatic humic-like components,whereas the neutral fractions had a greater content of aromatic proteins and soluble microbial byproduct-like components.Extraction of sludge organics with NH 3 ·H 2 O and subsequential fractionation using XAD resins could be a novel method for further characterization of sludge organics. 相似文献
993.
Samples obtained from an industrialized valley in the East Alpine region were collected daily for a half year and analyzed using X-ray fluorescence to examine the elements Si,Al,Fe,Ca,Mg,Na,K,Zn,P,S and Cl.Some factors affecting the changes of these elements were considered,including time,elemental correlations,weekday,weekend and seasonal changes.Diagnostic analysis provided an insight into a decoupling behavior that occursin siliceous and carbonates minerals.A decrease in Si and Al and an increase in carbonates,Na,K,Zn and P were observed during the cold season.However,a consistently high correlation of Si and Al was observed in all seasons.It was established that such high levels originated from street surface abrasion.The increase in variability and absolute levels of carbonates during the cold season was demonstrated by adding carbonates to the street surface as gritting material to increase the grip on snowy surfaces.A marked increase in Na and Cl was observed in winter which may have been caused by thaw salt that is widely used in winter in Austria.This was associated with a significant increase in K,Zn,and P in the cold season that was the result of domestic space heating with wood.PM10 levels in December were 12 μg/m3 and were higher than levels detected in July.It was established that such high levels originated from mineral oxides,wood smoke,and inorganic ionic material(s). 相似文献
994.
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
995.
The elemental composition and bacteria attached in particles were investigated during granular activated carbon (GAC) filtration.The experimental results showed that trapped influent particles could form new,larger particles on GAC surface.The sloughing of individuals off GAC surface caused an increase in effluent particles in the size range from 5 to 25 μm.The selectivity for element removal in GAC filters caused an increasing proportion of metallic elements in the effluent particles.The distribution of molar ratio indicated a complicated composition for large particles,involving organic and inorganic substances.The organic proportion accounted for 40% of total carbon attached to the particles.Compared with dissolved carbon,there was potential for the formation of trihalomethanes by organic carbon attached to particles,especially for those with size larger than 10 μm.The pure carbon energy spectrum was found only in the GAC effluent and the size distribution of carbon fines was mainly above 10 μm.The larger carbon fines provided more space for bacterial colonization and stronger protection for attached bacteria against disinfection.The residual attached bacteria after chorine disinfection was increased to 10 2-10 3 CFU/mL within 24 hours at 25°C. 相似文献
996.
Heavy metal (Pb,Zn) uptake and chemical changes in rhizosphere soils of four wetland plants with different radial oxygen loss 总被引:4,自引:0,他引:4
Lead and Zn uptake and chemical changes in rhizosphere soils of four emergent-rooted wetland plants; Aneilema bracteatum,
Cyperus alternifolius, Ludwigia hyssopifolia and Veronica serpyllifolia were investigated by two experiments: (1) rhizobag filled with
“clean” or metal-contaminated soil for analysis of Pb and Zn in plants and rhizosphere soils; and (2) applied deoxygenated solution for
analyzing their rates of radial oxygen loss (ROL). The results showed that the wetland plants with di erent ROL rates had significant
e ects on the mobility and chemical forms of Pb and Zn in rhizosphere under flooded conditions. These e ects were varied with
di erent metal elements and metal concentrations in the soils. Lead mobility in rhizosphere of the four plants both in the “clean”
and contaminated soils was decreased, while Zn mobility was increased in the rhizosphere of the “clean” soil, but decreased in the
contaminated soil. Among the four plants, V. serpyllifolia, with the highest ROL, formed the highest degree of Fe plaque on the root
surface, immobilized more Zn in Fe plaque, and has the highest e ects on the changes of Zn form (EXC-Zn) in rhizosphere under both
“clean” and contaminated soil conditions. These results suggested that ROL of wetland plants could play an important role in Fe plaque
formation and mobility and chemical changes of metals in rhizosphere soil under flood conditions. 相似文献
997.
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
998.
Evaluation of mercury speciation and removal through air pollution control
devices of a 190 MW boiler 总被引:1,自引:0,他引:1
Chengli Wu Yan Cao Zhongbing Dong Chinmin Cheng Hanxu Li Weiping Pan 《环境科学学报(英文版)》2010,22(2):277-282
Air pollution control devices (APCDs) are installed at coal-fired power plants for air pollutant regulation. Selective catalytic reduction
(SCR) and wet flue gas desulfurization (FGD) systems have the co-benefits of air pollutant and mercury removal. Configuration
and operational conditions of APCDs and mercury speciation a ect mercury removal e ciently at coal-fired utilities. The Ontario
Hydro Method (OHM) recommended by the U.S. Environmental Protection Agency (EPA) was used to determine mercury speciation
simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit. Chlorine in coal had been suggested as a factor
a ecting the mercury speciation in flue gas; and low-chlorine coal was purported to produce less oxidized mercury (Hg2+) and more
elemental mercury (Hg0) at the SCR inlet compared to higher chlorine coal. SCR could oxidize elemental mercury into oxidized
mercury when SCR was in service, and oxidation e ciency reached 71.0%. Therefore, oxidized mercury removal e ciency was
enhanced through a wet FGD system. In the non-ozone season, about 89.5%–96.8% of oxidized mercury was controlled, but only
54.9%–68.8% of the total mercury was captured through wet FGD. Oxidized mercury removal e ciency was 95.9%–98.0%, and there
was a big di erence in the total mercury removal e ciencies from 78.0% to 90.2% in the ozone season. Mercury mass balance was
evaluated to validate reliability of OHM testing data, and the ratio of mercury input in the coal to mercury output at the stack was from
0.84 to 1.08. 相似文献
999.
A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid(2,4-D) was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR,nitrogen adsorption and static adsorption experiments.The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol(2,4-DCP) mixture or using an aqueous 2... 相似文献
1000.
基于水热因子波动的呼伦贝尔草原产草量模型 总被引:1,自引:0,他引:1
基于多年气象资料(温度和降水量)和产草量监测数据,采用相关分析、主成分分析和回归分析等方法,构建呼伦贝尔草原产草量与气象因子统计学模型,并对二者之间的关系进行了分析.结果表明:利用水热波动因子建立的多项式回归模型具有较好的拟合效果,所建立的呼伦贝尔草原产草量预测模型为y=100.209+1.6410x-0.00559x2.F值显著性检验表明,其复相关系数R2=0.4713,F=8.0239(P=0.0033),在α=0.01水平上显著.利用1989─2009年呼伦贝尔草原产草量数据进行模型精度检验,模型预测精度在85%以上.该预测模型具有选用参数易得、易于代入遥感数据中进行栅格计算、精度高于基于植被指数预测模型等特点. 相似文献