Impact of global warming on agricultural product markets: stochastic world food model analysis

Climatic change through global warming and drought is a major issue for agricultural production. Most researchers who discuss the effects of such changes on agriculture report estimated yield changes based on crop process models. However, studies focusing on the impact of climatic change on agricultural product markets are very rare. This paper examines the relationship between climatic change and world food markets, i.e., the supply and demand of crops, by using a stochastic version of a world food model, the International Food and Agricultural Policy Simulation Model. The results suggest that variations in the production of maize and soybeans in some major producing countries will be large, and variations in the producer prices of all crops will increase. Countries that suffer higher price risk because of high sensitivity to temperature fluctuations may need to consider changes in cropping patterns.     

Dietary uptake kinetics of polychlorinated biphenyls from sediment-contaminated sandworms in a marine benthic fish (Pseudopleuronectes yokohamae)

To evaluate the dietary uptake of polychlorinated biphenyls (PCBs) from live food, we investigated the dietary uptake and depuration kinetics of PCBs in a marine benthic fish (marbled sole, Pseudopleuronectes yokohamae) by using as food live sandworms (Perinereis nuntia) that were laboratory-exposed to field-collected PCB-contaminated sediment. Marbled sole were fed the PCB-contaminated sandworms for 28 d and then uncontaminated sandworms for 56 d. The assimilation efficiencies (AEs) of 84 PCB congeners via the gastrointestinal tract (GIT) to the muscle of the fish ranged from 0.21 to 0.78; whole-body AEs would be lower than those of muscle because of the lower PCB concentrations, on a lipid basis. The AEs determined in this study were lower than those in other studies that used PCB-spiked commercial pelletized food. The lower AEs found in this study might be attributable to differences in the food administered (live sandworms vs. commercial pellet food), possibly because of low digestibility of sandworm lipids by marbled sole. In addition, the AEs in this study tended to increase with increasing log octanol-water partition coefficients (K_OW) up to about seven, although AEs in the other studies using commercial pelletized food did not increase with increasing log K_OW. This result suggests the co-transport of highly hydrophobic PCB congeners along with lipids and fatty acids from the digested sandworms into the GIT epithelium cells. The growth-corrected half-lives of 26 PCB congeners in the muscle of fish ranged from 20 to 107 d.     

Performance evaluation of intermediate cover soil barrier for removal of heavy metals in landfill leachate

This pilot-scale study evaluated the use of intermediate cover soil barriers for removing heavy metals in leachate generated from test cells for co-disposed fly ash from municipal solid waste incinerators, ash melting plants, and shredder residue. Cover soil barriers were mixtures of Andisol (volcanic ash soil), waste iron powder, (grinder dust waste from iron foundries), and slag fragments. The cover soil barriers were installed in the test cells' bottom layer. Sorption/desorption is an important process in cover soil bottom barrier for removal of heavy metals in landfill leachate. Salt concentrations such as those of Na, K, and Ca in leachate were extremely high (often greater than 30 gL(-1)) because of high salt content in fly ash from ash melting plants. Concentrations of all heavy metals (nickel, manganese, copper, zinc, lead, and cadmium) in test cell leachates with a cover soil barrier were lower than those of the test cell without a cover soil barrier and were mostly below the discharge limit, probably because of dilution caused by the amount of leachate and heavy metal removal by the cover soil barrier. The cover soil barriers' heavy metal removal efficiency was calculated. About 50% of copper, nickel, and manganese were removed. About 20% of the zinc and boron were removed, but lead and cadmium were removed only slightly. Based on results of calculation of the Langelier saturation index and analyses of core samples, the reactivity of the cover soil barrier apparently decreases because of calcium carbonate precipitation on the cover soil barriers' surfaces.     

Influence of temperature on product distribution and biochar properties by municipal sludge pyrolysis

Biochar has the potential to amend degraded soil and improve crop yield. An experiment involving municipal sludge pyrolysis was carried out in a horizontal quartz reactor over the temperature range of 300–700 °C. The aim of this work was to investigate the influence of pyrolysis temperature on product distribution and biochar properties required for agronomic applications. Results of the experiment showed that yield and energy conversion efficiency of biochar decreased as pyrolysis temperatures rose, while bio-oil and syngas increased gradually. Biochar aromaticity barely changed, while polarity gradually decreased and specific surface area increased with a rise in pyrolysis temperature. Nutritive elements showed different enriching characteristics in the sludge pyrolysis process: nitrogen failed to enrich in biochars, whereas both phosphorus and potassium were enriched. Heavy metals showed good stability in the pyrolysis process except chromium; the contents of all metals used in the biochar conformed to Chinese control standards for agronomic application.     

Estimation and field measurement of methane emission from waste landfills in Hanoi, Vietnam

A methodology for estimating the methane emissions from waste landfills in Hanoi, Vietnam, as part of a case study on Asian cities, was derived based on a survey of documents and statistics related to waste management, interviews with persons in charge, and field investigations at landfill sites. The waste management system in Hanoi was analyzed to evaluate the methane emissions from waste landfill sites. The quantity of waste deposited into the landfill was evaluated from an investigation of the waste stream. The composition of municipal waste was surveyed in several districts in the Hanoi city area, and the quantities of degradable organic waste that had been deposited into landfill for the past 15 years were estimated. Field surveys on methane emissions from landfills of different ages (0.5, 2, and 8 years) were conducted and their methane emissions were estimated to be 120, 22.5, and 4.38 ml/min/m², respectively. The first-order reaction rate of methane generation was obtained as 0.51/year. Methane emissions from waste landfills were calculated by a first-order decay model using this emission factor and the amount of landfilled degradable waste. The estimates of methane emissions using the model accorded well with the estimates of the field survey. These results revealed that methane emissions from waste landfills estimated by regional-specific and precise information on the waste stream are essential for accurately determining the behavior of methane emissions from waste landfills in the past, present, and future.     

Dynamic response of the scenic beauty value of different forests to various thinning intensities in central eastern China

Forest management has a significant influence on the preferences of people for forest landscapes. This study sought to evaluate the dynamic effects of thinning intensities on the landscape value of forests over time. Five typical stands in Wuxiangsi National Forest Park in Nanjing, China, were subjected to a thinning experiment designed with four intensities: unthinned, light thinning, moderate thinning, and heavy thinning. People’s preferences for landscape photographs taken in plots under various thinning intensities were assessed through scenic beauty estimation (SBE) at 2 and 5 years after thinning. The differences in scenic beauty value between different thinning intensities were then analyzed with a paired samples t test for the two periods. The results indicated that the landscape value of all of the thinned plots significantly exceeded that of the unthinned plots 2 years after thinning (p?相似文献   

High temperature air-blown woody biomass gasification model for the estimation of an entrained down-flow gasifier

A high temperature air-blown gasification model for woody biomass is developed based on an air-blown gasification experiment. A high temperature air-blown gasification experiment on woody biomass in an entrained down-flow gasifier is carried out, and then the simple gasification model is developed based on the experimental results. In the experiment, air-blown gasification is conducted to demonstrate the behavior of this process. Pulverized wood is used as the gasification fuel, which is injected directly into the entrained down-flow gasifier by the pulverized wood banner. The pulverized wood is sieved through 60 mesh and supplied at rates of 19 and 27kg/h. The oxygen-carbon molar ratio (O/C) is employed as the operational condition instead of the air ratio. The maximum temperature achievable is over 1400K when the O/C is from 1.26 to 1.84. The results show that the gas composition is followed by the CO-shift reaction equilibrium. Therefore, the air-blown gasification model is developed based on the CO-shift reaction equilibrium. The simple gasification model agrees well with the experimental results. From calculations in large-scale units, the cold gas is able to achieve 80% efficiency in the air-blown gasification, when the woody biomass feedrate is over 1000kg/h and input air temperature is 700K.     

Occurrence of tributyltin (TBT)-resistant bacteria is not related to TBT pollution in Mekong River and coastal sediment: with a hypothesis of selective pressure from suspended solid

Tributyltin (TBT) is organotin compound that is toxic to aquatic life ranging from bacteria to mammals. This study examined the concentration of TBT in sediment from and near the Mekong River and the distribution of TBT-resistant bacteria. TBT concentrations ranged from <2.4 to 2.4 ng/g (dry wt) in river sediment and <2.4-15 ng g(-1) (dry wt) in harbor sediment. Viable count of total bacteria ranged from 2.0 x 10(4) to 1.4 x 10(7)cfu/g, and counts of TBT-resistant bacteria ranged <1.0 x 10(2) to 2.5 x 10(4)cfu/g. The estimated occurrence rate of TBT-resistant bacteria ranged from <0.01 to 34% and was highest in upstream sites in Cambodia. The occurrences of TBT in the sediment and of TBT-resistant bacteria were unrelated, and chemicals other than TBT might induce TBT resistance. TBT-resistant bacteria were more abundant in the dry season than in the rainy season. Differences in the selection process of TBT-resistant bacteria between dry and rainy seasons were examined using an advection-diffusion model of a suspended solid (SS) that conveys chemicals. The estimated dilution-diffusion time over a distance of 120 km downstream from a release site was 20 days during dry season and 5 days during rainy season, suggesting that bacteria at the sediment surface could be exposed to SS for longer periods during dry season.     

Source-specific sewage pollution detection in urban river waters using pharmaceuticals and personal care products as molecular indicators

Environmental Science and Pollution Research - Source-specific elucidation of domestic sewage pollution caused by various effluent sources in an urban river water, as conducted for this study,...     

Statistical tools for analysing the data obtained from repeated dose toxicity studies with rodents: a comparison of the statistical tools used in Japan with that of used in other countries

In the present study, an attempt was made to compare the statistical tools used for analysing the data of repeated dose toxicity studies with rodents conducted in 45 countries, with that of Japan. The study revealed that there was no congruence among the countries in the use of statistical tools for analysing the data obtained from the above studies. For example, to analyse the data obtained from repeated dose toxicity studies with rodents, Scheffé's multiple range and Dunnett type (joint type Dunnett) tests are commonly used in Japan, but in other countries use of these statistical tools is not so common. However, statistical techniques used for testing the above data for homogeneity of variance and inter-group comparisons do not differ much between Japan and other countries. In Japan, the data are generally not tested for normality and the same is true with the most of the countries investigated. In the present investigation, out of 127 studies examined, data of only 6 studies were analysed for both homogeneity of variance and normal distribution. For examining homogeneity of variance, we propose Levene's test, since the commonly used Bartlett's test may show heterogeneity in variance in all the groups, if a slight heterogeneity in variance is seen any one of the groups. We suggest the data may be examined for both homogeneity of variance and normal distribution. For the data of the groups that do not show heterogeneity of variance, to find the significant difference among the groups, we recommend Dunnett's test, and for those show heterogeneity of variance, we recommend Steel's test.