Journal of Environmental Sciences - Volume 17, issue 2

Authors: PEI, Mei-xiang | LIN, He | SHANGGUAN, Wen-feng | HUANG, Zhen

Article Type: Research Article

Abstract: The simultaneous removal of NOx and particulate matter (PM) from diesel exhaust is investigated over a mixed metal oxide catalyst of La_{0.9} K_{0.1} CoO_3 loaded on γ-Al_2 O_3 spherules with the assistant of plasma. It was found that NOx was reduced by PM in oxygen rich atmosphere, the CO_2 and N_2 were produced in the same temperature window without considering the …N_2 formed by plasma decomposition. As a result, the temperature for the PM combustion decreases and the reduction efficiency of NOx to N_2 increases during the plasma process, which indicated that the activity of the catalyst can be improved by plasma. The NOx is decomposed by plasma at both low temperature and high temperature. Therefore, the whole efficiency of NOx conversion is enhanced. Show more

Keywords: simultaneous removal, plasma assisted catalysis, NOx, PM, diesel

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 220-223, 2005

Authors: CHEN, Li-ding | PENG, Hong-jia | FU, Bo-jie | QIU, Jun | ZHANG, Shu-rong

Article Type: Research Article

Abstract: Surface waters can be contaminated by human activities in two ways: (1) by point sources, such as sewage treatment discharge and storm-water runoff; and (2) by non-point sources, such as runoff from urban and agricultural areas. With point-source pollution effectively controlled, non-point source pollution has become the most important environmental concern in the world. The formation of non-point source pollution is related to both the sources such as soil nutrient, the amount of fertilizer and pesticide …applied, the amount of refuse, and the spatial complex combination of land uses within a heterogeneous landscape. Land-use change, dominated by human activities, has a significant impact on water resources and quality. In this study, fifteen surface water monitoring points in the Yuqiao Reservoir Basin, Zunhua, Hebei Province, northern China, were chosen to study the seasonal variation of nitrogen concentration in the surface water. Water samples were collected in low-flow period (June), high-flow period (July) and mean-flow period (October) from 1999 to 2000. The results indicated that the seasonal variation of nitrogen concentration in the surface water among the fifteen monitoring points in the rainfall-rich year is more complex than that in the rainfall-deficit year. It was found that the land use, the characteristics of the surface river system, rainfall, and human activities play an important role in the seasonal variation of N-concentration in surface water. Show more

Keywords: non-point source pollution, nitrogen concentration, seasonal variation, land use, Yuqiao Reservoir Basin, China

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 224-231, 2005

Authors: ZOU, Chun-jing | HAN, Shi-jie | QI, Shu-yan | XU, Wen-duo | LI, Dao-tang

Article Type: Research Article

Abstract: Picea mongolica W. D. Xu. is an endemic species in China. The spruce forest is only found in semi-arid habitat in Inner Mongolia Autonomous Region of China. Based on the simulative defoliation experiment, it was proved that Picea mongolica seedlings had the compensatory and overcompensatory effects under the certain defoliation rate. The results of variance analysis on growth indexes showed that in PM I (natural regeneration seedlings under Picea mongolica forest), the differences of H_1 …(height in June 23) and H_2 (height in September 3) were extremely significant, and the difference of D(diameter at the breast height) were not significant. In PM II (artificial regeneration seedlings under Betula platyphylla Suk. forest), the difference of H_1 was significant, the difference of H_2 was not significant, and the difference of D was extremely significant. The regression equations were established and the compensatory and overcompensatory points were obtained. In PM I, the compensatory points of H_1 , H_2 , and D were 0.7628, 0.7436, 0.5725, and the overcompensatory points were 0.6056, 0.5802 and 0.2909 respectively. In PM II, the compensatory points of H_1 , H_2 , and D are 0.5012, 0.3421, 0.2488, and the overcompensatory points are 0.4137, 0.2633 and 0.0747 respectively. These results suggested that the induction of compensatory growth mechanisms in spruce seedlings required a threshold level of defoliation, and the insects in Picea mongolica forest could be controlled in a certain degree. Show more

Keywords: Picea mongolica W. D. Xu, compensate, overcompensate, growth, defoliation rate

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 232-236, 2005

Authors: WEN, Yue-zhong | ZHOU, Shan-shan | FANG, Zhao-hua | LIU, Wei-ping

Article Type: Research Article

Abstract: The effect of β-cyclodextrins (β-CDs) on the enzymatical hydrolysis of chiral dichlorprop methyl ester (DCPPM) was studied.Four kinds of β-cyclodextrins (β-cyclodextrin, Partly methylated-CD (PM-β-CD), hydroxypropyl-cyclodextrin (HP-β-CD) and carboxymethyl-cyclodextrin (CM-β-CD) ) were used. Compared with 100% DCPPM in the absence of β-cyclodextrins, the activity of lipase decreased with the increase of β-cyclodextrin and PM-β-cyclodextrin. However, CM-β-cyclodextrin stimulated the lipase activity. The …inhibition effect of β-cyclodextrin and PM-β-cyclodextrin on the hydrolysis of DCPPM is affected by many factors other than degree of the methylation blocking the active site of lipase. UV-Vis and Fourier transform infrared (FTIR) spectroscopy studies of the complexation of aqueous DCPPM with β-CDs provide fresh insight into the molecular structure of the complex and explain the effects of β-CDs on enzymatical hydrolysis of chiral DCPPM. Data showed that inclusion complexes had formed by complexation of the CM-β-CD with DCPPM and the solubility of DCPPM was increased in water, which leaded to the increased lipase activity. Show more

Keywords: β-cyclodextrins, enzyme, hydrolysis, chiral, dichlorprop

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 237-240, 2005

Authors: SUN, Xiang-wu | WENG, Huan-xin | QIN, Ya-chao

Article Type: Research Article

Abstract: The release process and influencing factors of bioactive iodine of kelp are systemically studied by leaching experiment. The results showed that the bioactive iodine of kelp can be released rapidly and the principal form of iodine in lixivium is I^- . There is a dynamic process between the release and absorption of iodine. With the increase of leaching water, the gross amounts of released iodine rise. There also exists a transforming process among I^- …, IO_3^- and organic iodine in lixivium. Show more

Keywords: kelp iodine, absorption, release, lixivium

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 241-244, 2005

Authors: LIU, Rui-xiang | GAO, Xi-yan | YANG, De-sheng | XU, Xiao-guang

Article Type: Research Article

Abstract: The exhaust gas recirculation (EGR), coupled with a high-collection efficiency particulate trap to simultaneously control smoke and NOx emissions from diesel engines were studied. This ceramic trap developed previously provided the soot cleaning efficiency of 99%, the regeneration efficiency reaches 80% and the ratio of success reaches 97%, which make EGR used in diesel possible. At the presence of EGR, opening of the regeneration control valve of the trap was over again optimized to compensate for …the decrease of the oxygen concentration in the exhaust gas resulted from EGR. The results indicated the cleaning efficiency and regeneration performance of the trap were maintained at the same level except that the back pressure increased faster. A new EGR system was developed, which is based on a wide range oxygen(UEGO) sensor. Experiments were carried out under steady state conditions while maintaining the engine speed at 1600 r/min, setting the engine loads at 0%, 25%, 50%, 75% and 100% respectively. Throughout each test the EGR rate was kept at nine different settings and data were taken with the gas analyzer and UEGO sensor. Then, the EGR rate and engine load maps, which showed the tendencies of NOx, CO and HC emissions from diesel engine, were made using the measured data. Using the maps, the author set up the EGR regulation, the relationship between the optimal amounts of EGR flow and the equivalence ratio, σ, where σ = 14.5/AFR. Show more

Keywords: particulate trap, EGR, NOx, soot, UEGO

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 245-248, 2005

Authors: ZHANG, Bo | HE, Zheng-guang | ZHANG, Li-li | XU, Jian-bo | SHI, Hong-zhuan | CAI, Wei-min

Article Type: Research Article

Abstract: The performance of the single-stage anaerobic digestion of kitchen wastes was investigated in an anaerobic sequencing batch reactor (ASBR) with gas-phased absorb of CO_2 . The ASBR was operated at four chemical oxygen demand (COD) loading rates, 2.8, 5.1, 6.2 and 8.4 g/(L·d) respectively. The COD loading rate was increased with the TS concentration and HRT changing. At maximum COD loading rate of 8.4 g (L·d), The COD, total solid (TS) removal rate and methane …gas yield were 69%, 68% and 2.5 L(L·d) respectively. The operation of the reactor with gas-phased absorb of CO_2 was stable in spite of the low pH (2.6–3.9) and high concentration of TS (142 g/L) of input mixture. The output volatile fatty acid (VFA) concentration was between 2.7–4.7 g/L and had no inhibition on the methanogenic microorganism. The reactor without gas-phased absorb of CO_2 became acidified when the total COD alkaline will be required to keep pH in the appropriate range for the methanogenic microorganism based on theoretical calculation. Gasphased absorb of CO_2 effectively reduced the alkaline consumption, hence avoided excessive cation into the reactor. Show more

Keywords: kitchen wastes, methanogenesis, gas-phased, CO_2

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 249-255, 2005

Authors: JI, Xiu-ling | YANG, Liu | SHEN, Zhe-min | CHENG, Jin-ping | JIN, Gui-wen | QU, Li-ya | WANG, Wen-hua

Article Type: Research Article

Abstract: The neurotransmitter level changes of ducks exposed 8-month in a mercury-polluted site (Wanshan, China) and a reference site (Shanghai, China) were examined. Chemical analyses showed both higher mercury and selenium concentrations in the organ of Wanshan ducks. An increased content of acetylcholine (ACh) in brain and blood and a decreased activity of acetylcholinesterase (AChE) in blood were observed. Moreover, there was an increasing trend for nitric oxide synthase (NOS) activity and nitric oxide (NO) …production in duck brain, but a reduction of NOS activity in duck serum. The possible explanations were due to the interactive effect of selenium accumulation and the sublethal exposure level of mercury in Wanshan area. The present study showed that AChE and NOS were sensitive to mercury contamination of real circumstance, suggesting that these two indexes have the potential to be biomarkers in assessment of health effects by mercury contamination. Show more

Keywords: mercury, neurotransmitter, long-term exposure, Wanshan area

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 256-258, 2005

Authors: YU, Bing-jun | LAM, Hon-ming | SHAO, Gui-hua | LIU, You-ling

Article Type: Research Article

Abstract: The effects of NaCl stress on the H^+ -ATPase, H^+ -PPase activity and lipid composition of plasma membrane (PM) and tonoplast (TP) vesicles isolated from roots and leaves of two soybean cultivars (Glycine max L.) differing in salt tolerance (Wenfeng7, salt-tolerant; Union, salt-sensitive) were investigated. When Wenfeng7 was treated with 0.3% (W/V) NaCl for 3 d, the H^+ -ATPase activities in PM and TP from roots and leaves exhibited a reduction and an …enhancement, respectively. The H^+ -PPase activity in TP from roots also increased. Similar effects were not observed in roots of Union. In addition, the increases of phospholipid content and ratios ofphospholipid to galactolipid in PM and TP from roots and leaves of Wenfeng7 may also change membrane permeability and hence affect salt tolerance. Show more

Keywords: salinity, Glycine max L., plasma membrane, tonoplast, H^+-ATPase, H-P^+Pase, membrane lipid composition

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 259-262, 2005

Authors: ZENG, Wei-hua | CHENG, Sheng-tong

Article Type: Research Article

Abstract: Environmental risk (ER) fact ore come from ER source and they are controlled by the primary control mechanism (PCM) of environmental risk, due to the self failures or the effects of external environment risk trigger mechanism, the PCM could not work regularly any more, then, the ER factore will release environmental space, and an ER field is formed up. The forming of ER field does not mean that any environmental pollution accident (EPA) will break out; …only the ER receptore are exposed in the ER field and damaged seriously, the potential ER really turns into an actual EPA. Researching on the general laws of evolving from environmental risk to EPA, this paper bring forwards a relevant concept model of risk forecasting and evaluating of EPA. This model provides some scientific methods for risk evaluation, prevention and emergency response of EPA. This model not only enriches and develops the theory system of environment safety and emergency response, but also acts as an instruction for public safety, enterprise's safety management and emergency response of the accident. Show more

Keywords: environmental risk (ER), environmental pollution accident (EPA), ER evaluation, ER field, EPA damage field

Citation: Journal of Environmental Sciences, vol. 17, no. 2, pp. 263-267, 2005