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111.
Li LY Ohtsubo M Higashi T Yamaoka S Morishita T 《Waste management (New York, N.Y.)》2007,27(7):932-945
In Japan the volume of municipal solid waste is reduced by incineration, with fly ash and bottom ash disposed in controlled landfills. The leachability of anions and heavy metal cations, Zn, Cu and Pb, from MSW fly ash and bottom ash at different pHs was examined using batch- and column-leaching tests. The MSW ashes had a high capacity for neutralizing acids. Behaviour during leaching depended on the pH of the solution. For the volumes applied, the leachabilities of MSW fly ash were very similar at pHs from 3 to 6. Due to its amphoteric nature, Pb is leachable at pHs of approximately 10 or more, with leachate concentrations of about 3 and 3-10mg/L for the fly ash and bottom ash, respectively, much higher than for Zn and Cu. Pb concentrations for most leaching solutions were 1 and 3mg/L for the fly ash and bottom ash, respectively. Zn, and Cu leached at low concentrations for solutions of pH 3-6. Na and K ions leached at high concentrations of approximately 5000 mg/L in the first batch leaching test, decreasing to 10mg/L by the fourth leach. Ca and Mg ions leached more gradually than Na and K. Cl(-) and SO(4)(2+) ions were the major anions in the MSW ash. The high pH and cation leaching are expected to have negative impacts on the performance of clay liners. 相似文献
112.
Landfill leachate treatment using a rotating biological contactor and an upward-flow anaerobic sludge bed reactor 总被引:2,自引:0,他引:2
This paper describes the feasibility of an aerobic system (rotating biological contactor, RBC) and a biological anaerobic system (upward-flow anaerobic sludge bed reactor) at small scale for the treatment of a landfill leachate. In the first phase of the aerobic system study, a cyclic-batch RBC system was used to select perforated acetate discs among three different acetate disc configurations. These discs were chosen on the basis of high COD removal (65%) and biological stability. In the second phase, the RBC system (using four stages) was operated continuously at different hydraulic retention times (HRT), at different rotational speeds, and with varying organic concentrations of the influent leachate (2500-9000mgL(-1)). Forty percent of the total surface area of each perforated disc was submerged in the leachate. A COD removal of about 52% was obtained at an HRT of 24h and a rotational speed of 6rpm. For the anaerobic system, the reactor was evaluated with a volumetric organic load of 3273g-COD m(-3) day(-1) at an HRT of 54, 44, 39, 24 and 17h. At these conditions, the system reached COD removal efficiencies of 62%, 61%, 59%, 44% and 24%, respectively. 相似文献
113.
The technical viability of using inert construction and demolition (C&D) materials for the construction of seawall and breakwater foundations has been established by laboratory testing of the materials, numerical analysis of foundation stability, and a pilot field-scale engineering performance evaluation. However, quality control measures are still required so that only suitable materials are used for seawall and breakwater foundation construction. The development of different quality control measures for different site conditions is presented in this paper. The rationale, practicality, and implementation of these quality control measures are also discussed. 相似文献
114.
Boivin ME Greve GD García-Meza JV Massieux B Sprenger W Kraak MH Breure AM Rutgers M Admiraal W 《Environmental pollution (Barking, Essex : 1987)》2007,145(3):884-894
The aim of the present study was to investigate algal-bacterial interactions in a gradient of metal contaminated natural sediments. By means of multivariate techniques, we related the genetic structure (denaturing gradient gel electrophoresis, DGGE) and the physiological structure (community-level physiological profiling, CLPP) of the bacterial communities to the species composition of the algal communities and to the abiotic environmental variables, including metal contamination. The results revealed that genetic and physiological structure of the bacterial communities correlated with the species composition of the algal community, but hardly to the level of metal pollution. This must be interpreted as an indication for a strong and species-specific linkage of algal and bacterial species in floodplain sediments. Metals were, however, not proven to affect either the algal or the bacterial communities of the Dutch river floodplains. 相似文献
115.
Source apportionment of polycyclic aromatic hydrocarbons in surface soil in Tianjin, China 总被引:15,自引:0,他引:15
Zuo Q Duan YH Yang Y Wang XJ Tao S 《Environmental pollution (Barking, Essex : 1987)》2007,147(2):303-310
Principal component analysis and multiple linear regression were applied to apportion sources of polycyclic aromatic hydrocarbons (PAHs) in surface soils of Tianjin, China based on the measured PAH concentrations of 188 surface soil samples. Four principal components were identified representing coal combustion, petroleum, coke oven plus biomass burning, and chemical industry discharge, respectively. The contributions of major sources were quantified as 41% from coal, 20% from petroleum, and 39% from coking and biomass, which are compatible with PAH emissions estimated based on fuel consumption and emission factors. When the study area was divided into three zones with distinctive differences in soil PAH concentration and profile, different source features were unveiled. For the industrialized Tanggu-Hangu zone, the major contributors were cooking (43%), coal (37%) and vehicle exhaust (20%). In rural area, however, in addition to the three main sources, biomass burning was also important (13%). In urban-suburban zone, incineration accounted for one fourth of the total. 相似文献
116.
C. T. Achuthankutty Y. Shrivastava G. G. Mahambre S. C. Goswami M. Madhupratap 《Marine Biology》2000,137(1):19-22
Effect of salinity on the feeding rate and parthenogenetic reproduction of asexual females of the cladoceran Diaphanosoma celebensis Stingelin was studied. Short-term (10 h) grazing experiments were conducted using Isochrysis galbana as feed at 5, 17, 25 and 30 psu salinity. Gut pigment concentration showed a significantly higher rate of feeding at lower
salinities. Survival, growth, maturity attainment and neonate production of asexual females reared in the above four test
salinities indicated preference for lower salinities (5 and 17 psu). The mean size of adult females decreased from 909 to
593 μm, mean life span from 24 to 5 d, mean neonate production from 12 to 2 and mean size of neonates from 434 to 400 μm as
the salinity increased from 5 to 30 psu. Salinity variations also affected the size and age of primiparous females. Resting
egg formation and sexual reproduction did not occur at the tested salinities. The results indicate that D. celebensis is adapted to low saline, estuarine environments.
Received: 14 January 2000 / Accepted: 24 March 2000 相似文献
117.
The pathway for the flow of salt-marsh grass production into marsh food-webs is still not well defined. We compared the abilities
of three marsh macroinvertebrates [salt marsh periwinkles, Littoraria irrorata (Say) (=Littorina irrorata), salt-marsh coffee-bean snails, Melampus bidentatus (Say); and a talitrid amphipod, Uhlorchestia spartinophila Bounsfield and Heard] to access standing-dead leaves of smooth cordgrass (Spartina alterniflora Loisel). The invertebrates were incubated with naturally-decaying leaves, and the rates of removal of organic matter and
living fungal biomass (ergosterol) were measured. The impact of invertebrate activity upon fungal growth rates was measured
as rates of fungal-membrane synthesis (incorporation of radioacetate into ergosterol). The removal rates of organic leaf biomass
per mg individual biomass were highest for amphipods (700 μg mg−1 d−1) and lowest for periwinkles (90 μg mg−1 d−1), but the relatively large biomass of the snails made their removal rates per individual greater than those of amphipods.
Net removal of ergosterol by all three invertebrates was >50% for yellow-brown (early-decay) leaf blades. For fully-brown
(advanced-decay) blades, >50% removal of ergosterol was found only for periwinkles; exposure to coffee-bean snails and amphipods
resulted in a net ergosterol reduction of ≤20%. The lower net reduction of living fungal biomass by coffee-bean snails and
amphipods may have been due to fungal-growth stimulation (2.3-fold stimulation in coffee-bean snails and 1.5-fold stimulation
in amphipods). Grazing by periwinkles did not stimulate fungal growth, possibly because of its high intensity. Grazing by
these three salt-marsh shredders may affect marsh-grass shoot-decay in different ways. Periwinkles may abbreviate the period
of fungal production, and incorporate the decaying material relatively quickly into snail biomass and fecal-pellet rain to
the sediments. Coffee-bean snails and amphipods may enhance and prolong fungal production, along with the formation of fecal-pellet
rain. All three invertebrates fed preferentially on leaf blades rather than leaf sheaths, and feeding rates of gastropods
were higher during the night than during the day.
Received: 25 November 1998 / Accepted: 4 November 1999 相似文献
118.
In many salmonid species, males exhibit morphological dimorphism associated with alternative mating behaviors. ”Precocious
males” have a small body size with little or no development of sexual characters and adopt sneaking to gain access to females,
while ”migratory males” of large body size and well-developed secondary sexual characters fight. We quantified selection on
precocious male parr of masu salmon (Oncorhynchus masou) under simulated natural conditions to examine the contribution of morphology to sneaking success. In contrast to the prediction
that sneaking behavior favors small body size, we detected selection favoring relatively large body size for sneaking success.
This selection pressure was caused by the dominance hierarchy within parr and may have been facilitated by indifference of
dominant migratory males to parr. Unlike the secondary sexual characters exhibited by migratory male salmon, such as the hooked
snout and humped back, no morphological characters other than body size contributed to the reproductive success of masu salmon
parr. This non-contribution may have been responsible for the lack of development of sexual characters in precocious males.
Received: 15 November 1999 / Accepted: 20 May 2000 相似文献
119.
120.
T. Chen M. Liu Y. Takahashi J.D. Mullen G.C.W. Ames 《Journal of Environmental Planning and Management》2016,59(6):948-966
Three different sizes of hog farms were selected to analyze the carbon emissions reduction and the cost–benefit of three methane digester systems. The sizes of the digesters are 2,200, 2,200 and 800 m3, respectively. The sales of slaughter hogs from them are 50,000, 35,000 and 10,000 head, respectively. The carbon emissions reductions were 5,237, 4,017, and 1,334 tons, respectively. The results show that while the methane digester systems have a significant effect on carbon emissions reduction, it is difficult to operate the systems sustainably. If the carbon emissions reduction can be traded at high enough prices in the carbon offset markets, then the systems will be profitable and sustainable. Newly established China's domestic carbon offset market could provide this possibility, but more government support is needed. In addition, this study shows that scale economies make the digester adoption relatively more profitable for larger farms than smaller ones. 相似文献