Applied Mechanics and Materials Vols. 316-317

Abstract: In Zhengxiangbaiqi, the Sanmianjing Formation of Middle Permian exposes most completely. The Lithology is mainly clastic rocks, in the lower part of the section, there are 60m gray middle-thick-bedded limestone. Based on detailed measurement of the Elitu Pasture Ⅱ, indoor research, identifications with microscope, paleontology and sequence stratigraphy studies, explored sedimtentary facies and sedimentary paleoenvironment of the Sanmianjing formation. The lower part and the upper part of Sanmianjing formation might be deposited in a shore setting with a high energy, and the middle part might be formed in an epicontinental sea with a relative low-energy. Fossils and sedimentary facies further enrich the biological face of the section, and prove new informations for contrasting between different stratigraphic and plaeoenvironment. This study proved principal geological data for further research on palaeogeography, oil and gas exploration.

Abstract: The fast-growing and high-yielding timber plantation base construction engineering initiated in 2002, and it’s the sixth largest forest project in China. Did the project have influence to the grain production in the past ten years And how much the influence is Based on this problem, the study selects Hebei province as the research area, which is around Beijing-Tianjin, and the geographical position is particularly important. It analyzes Hebei’s fast-growing trees planting area, grain sown area and yield from land using angle. Research shows that fast-growing trees planting’s time and space difference is very wide in Hebei and each city, but its influence is very small for the grain sown area, and has no effect on total grain yield. Because Fast-growing trees can improve ecological environment and bring huge economic benefits, it can continue to be planted in Hebei’s suitable area in the future. The fast-growing trees planting should occupy less cultivated land as far as possible, and reduce the influence to grain production.

Abstract: Although heptachlor epoxide (HE) is the major metabolite of organochlorine pesticide heptachlor in soil, there is very limited information on the biodegradation of HE by microorganisms, and no systematic study on the metabolic products and pathways for HE transformation by fungi has been conducted. In this study, the metabolism of HE was performed with Cordyceps brongniartii ATCC66779, which is capable of degrading polychlorinated dibenzo-p-dioxin. This fungus removed about 27% and 21% of HE in PDB and BSM medium, respectively, after 20 days of incubation. Three hydroxylated products including heptachlor diol, 1,2-dihydroxydihydrochlordene and trihydroxychlordene were detected as metabolites of HE using GC/MS analysis, suggesting that HE was metabolized to hydrophilic products via hydrolysis, dechlorination and hydroxylation.

Abstract: The soil organic carbon density and storage of Maiji Area of Tianshui was estmiated, using the data of 6060 soil profile from the second soil survey of China and formulating fertilization for soil conditions in 2008. Integrating the soil map, land use status map and district map of Maiji Area of Tianshui, the index of the characteristic of soil organic distribution in different soil and soil layers were analyzed. Results showed: the soil of Maiji area have low average density, when soil secondary census, depths of 5cm,20cm,1m average density of organic carbon are 0.92kg•m-2,3.31kg•m-2,7.79kg•m-2 respectively, average density of organic carbon at depth of 20cm is 2.43 kg•m-2 in 2008 years, As a standard of Yu Dongsheng’s (2005) estimation of average density of 9.60 kg•m-2 in the depth of 1m all over the China, Maiji area 1m deep soil organic carbon density is lower 1.91kg•m-2 than the average density of whole country; The calculation of the secondary survey, reserves of organic carbon in surface soil (0-5cm) is about 4.83×106t, reserves of organic carbon in fall (0-20cm) is about 12.46×106t, reserves of soil organic carbon in 1m depth is about 45.17×106t, reserves of soil organic carbon in fall (0-20cm) is about 18.55×106t in 2008 years. In a word, the soil organic carbon storage was relatively indigent in Maiji Area of Tianshui.

Abstract: Heavy metal was the biggest obstacles of sludge harmless and resources utilization. Studies have been conducted to investigate the effect of salinity on heavy metal from excess sludge. The static experiments were carried out to observe the release of Cu and Pb at four levels of salinity (20‰, 25‰, 30‰, 35‰). The results showed that Cu and Pb presented a similar trend over time: The concentration gradually increased over time in the early period, when reaching the highest value it begun to decrease, until relatively stabilized. Cu and Pb were more favorable to release in higher salinity levels, especially 35‰. The maximum concentration of Cu and Pb was 0.121ug.L-1 and 1.056 ug.L-1, respectively. And Pb was easier to release than Cu.

Abstract: In this paper the effects of compound sulfur-fixing agents and compound additives on the sulfur-fixing efficiency were discussed. Thermogravimetric Analysis was used to study the influence of sulfur-fixing agent and additives on the combustion performance. Besides, X-ray fluorescence was applied to research sulfur-fixing mechanism. The results show that, the best sulfur-fixing efficiency was 78.95%, when the ratio of Ca/S was 2.0, experimental temperature was 1000°C, burning time was 20min, the compound sulfur-fixing agents were 80% carbide slag and 20% wastes, the compound additives were 2% iron additives, 6% aluminum additives, 4% sodium additives, 5% silicon additives. The effects of the four additives on the sulfur-fixing efficiency were Al＞Fe＞Si＞Na.

Abstract: To reveal relationship between water content of plant tissue and soil moisture in the hinterland of Taklimakan desert in China's southern Xinjiang, Haloxylon ammodendron and Nitraria sibirica were selected, and the water potential and content in the tissues of two plants under drought stress were determined. The results were shown that: (1) water potential in the morning and the water content in the tissues of Haloxylon ammodendron and Nitraria sibirica decreased with the decline of soil moisture content. (2) When the soil water stress appeared, the water potential values of Haloxylon ammodendron and Nitraria sibirica were -4.47 MPa and -5.88 MPa, respectively. (3) The lower limits of soil moisture contents that were suitable for the growth of Haloxylon ammodendron and Nitraria sibirica were 2.50% and 3.00%, respectively.

Abstract: Dissolved organic matter (DOM) may do harms to human beings. After disinfected by chlorine (amine), DOM can form disinfection by-products (DBPs) which can be mutagenic, teratogenic and carcinogenic. Characterization and source of trihalomethane precursors in the secondary effluent by sequencing batch reactors were investigated. CHCl3 was the primary DBPs. The results showed that the precursors of CHCl3 were mainly strongly hydrophobic DOM, while CHCl2Br and CHClBr2 were mainly formed from hydrophilic DOM. The effects of different powder media (activated carbon, zeolite) on removal of DOM were compared. The results showed that the dosing of powder media can promote the removal of DOM and the DBPs precursors.

Abstract: Perfluorooctanoic acid (PFOA), one of persistent organic pollutants (POPs), has prompted much concern in the last fifty years. Its accumulation in the natural environment is increased, and its threats to ecosystems have been discovered. Because of the highly stable, PFOA was hardly decomposed and defluorination. In previous study, a photo-reduction method is developed for the decomposition of PFOA in Milli-Q water with potassium iodide (KI) as a mediator. But this system wasn’t discussed in natural environment. In this study, several common inorganic ions in the surface water were been choice as the object. By analyzing the matrix effects of different kinds of anions and cations to the photo-reductive defluorination of PFOA, it shows that the presence of anions in the system will heavily inhibit the degradation process, while the impact of cations to the degradation is related to the concentration. And, both anions and cations can inhibit the defluorination process, but anions have much greater impact than the cations to the defluorination rate.

Abstract: Perfluorinated chemicals (PFCs) are anthropogenic contaminants which have prompted much concern regarding their environment persistence and bioaccumulation. The main sources of PFCs are from wastewater of fluorine chemical. Decomposition and defluorination of PFCs in wastewater by photo-induced hydrated electrons was well and firstly investigated in this paper. In this work the proposed method was tested to deal with PFCs containing wastewaters from a Teflon-manufacturing plant in Jiangsu Province, China. 95.5% of perfluorooctanoic acid (PFOA) was decomposed after 12 hours treatment and defluorination rate of PFCs could reach about 60%. PFCs were transformed into harmless fluoride, acetic acid and formic acid. It was suggested this system can efficiently decompose PFCs from fluorine chemical plant. In brief, this study demonstrates that the photo-reduction is a high efficient, energy-saving method which produced less-toxic products for PFCs removal, compared with activated carbon absorption and combustion.