Journal of Environmental Sciences - Volume 18, issue 2

Authors: Batayneh, Awni T. | Qassas, Hani A.

Article Type: Research Article

Abstract: The demand for water resources in the area south of the Dead Sea due to continued development, especially at the Arab Potash Company (APC) for production and domestic purposes necessitates that water quality in the area be monitored and evaluated based on the local geology and hydrogeology. The objective of this paper is to monitor seasonal fluctuations of groundwater and to determine how fluctuation in the water levels will affect the groundwater quality. Groundwater levels were …found to be influenced by rainfall and pumping of water from the wells for domestic and industrial use. Twenty water samples were collected from different wells and analyzed for major chemical constituents both in pre- and post-seasons to determine the quality variation. Chemical constituents are significantly increased after post-season recharge. According to the overall assessment of the area, water quality was found to be useful for drinking, irrigation and industry. Show more

Keywords: water level fluctuations, seasonal variations, quality, Dead Sea coastal aquifers, Jordan

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 263-269, 2006

Authors: HAO, Qing-ju | WANG, Yue-si | SONG, Chang-chun | HUANG, Yao

Article Type: Research Article

Abstract: Wetlands at the interface of the terrestrial and aquatic ecosystems are intensive sites for mineralization of organic matter, but the contribution of winter season fluxes of CH_4 , CO_2 and N_2 O from wetland ecosystems to annual budgets is poorly known. By using the static opaque chamber and GC techniques, fluxes of CH_4 , CO_2 and N_2 O at two freshwater marshes in the Sanjiang Plain were measured …during the winter seasons of 2002/2003 and 2003/2004 with contrasting snow conditions and flooding regimes. The results showed that there were significant interannual and spatial differences in CH_4 , CO_2 and N_2 O fluxes. The Carex lasiocarpa marsh emitted more CH_4 and CO_2 while absorbed less N_2 O than the Deyeuxia angustifolia marsh during the winter seasons. Over the winter season, emissions of CH_4 , CO_2 and N_2 O ranged from 0.42 to 2.41 gC/m^2 , from 24.13 to 50.16 gC/m^2 , and from −25.20 to −148.96 mgN/m^2 , respectively. The contributions of winter season CH_4 and CO_2 emission to the annual budgets were 2.32%–4.62% and 22.17%–27.97%, respectively. Marshes uptake N_2 O during the freezing period, while release N_2 O during the thawing period. The winter uptake equaled to 13.70%–86.69% of the growing-season loss. We conclude that gas exchange between soil/snow and the atmosphere in the winter season contributed greatly to the annual budgets and cannot be ignored in a cool temperate freshwater marsh in Northeast China. Show more

Keywords: freshwater marsh, winter flux, greenhouse gas emission, Sanjiang Plain

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 270-275, 2006

Authors: GUO, Yu-fang | YE, Dai-qi | CHEN, Ke-fu

Article Type: Research Article

Abstract: A superimposed wire-plate dielectric barrier discharge reactor was used to remove toluene in this study. The effects of oxygen content, gas flow rate, gas initial concentration and with/without catalyst on toluene decomposition were investigated. It was found that an optimal toluene removal was achieved when the oxygen content was about 5%. Under this condition, the highest toluene removal efficiency of 80.8% was achieved when the gas concentration was 80 mg/m^3 . The toluene removal efficiency …decreased with the increase of the gas flow rate and the initial concentration of toluene. In addition, the ozone concentration decreased with the increase of the initial concentration of toluene. It suggested that combining DBD (dielectric barrier discharge) with Co_3 O_4 /Al_2 O_3 /foam nickel catalyst in-situ could improve the toluene removal efficiency and suppress ozone formation. Products analysis showed that the main products were CO and CO_2 when oxygen was more than 5%. Show more

Keywords: dielectric barrier discharge (DBD), plasma, oxygen content, catalyst, toluene, product analysis

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 276-280, 2006

Authors: ZHAO, Yi | XU, Pei-yao | FU, Dong | HUANG, Jian-jun | YU, Huan-huan

Article Type: Research Article

Abstract: Simultaneous removal of SO_2 and NO from flue gas by the highly active absorbent prepared from fly ash, lime and a few oxidizing manganese compound additive was studied using a flue gas circulating fluidized bed (CFB) under different experimental conditions. The effects influencing the removal effiencies were discussed. The optimal flue gas temperature, flue gas humidity, gas velocity of CFB and Ca/(S+N) molar ratio with this process were approximately 110°C, 6%, 1.8 m/s and …1.05, respectively. Removal efficiencies of 92.3% for SO_2 and 60.88% for NO were obtained under the optimal experimental conditions. While the spent absorbent appeared in the form of dry powder, the mechanism of removal for SO_2 and NO based on the highly active absorbent was investigated by a scanning electron microscope (SEM), a X-ray energy spectrometer and the chemical analysis methods. The valuable references can be provided for industrial application by the process. The foreground of application will be vast in China and in the world. Show more

Keywords: simultaneous desulfurization and denitrification, CFB, removal efficiency, mechanism

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 281-286, 2006

Authors: LIU, Wen-ju | Kim, Kyoung-woong | ZHU, Yong-guan | LEE, Sang-woo | CHANG, Pei-chun | Kwak, Ji-hyun

Article Type: Research Article

Abstract: This research includes two investigations. The first one is a market basket survey of the levels of arsenic (As) and trace elements in bracken fern (Pteridium aquilinum) originated from three countries: South Korea, China and North Korea. The results showed that the mean As concentrations in stems of samples were significantly higher than those in leaves. As concentrations in all samples did not exceed food safety limits for vegetables. Generally, concentrations of Fe, Mn, Cu and …Zn in leaves were higher than those in stems. The second investigation is a survey on the levels of As and other heavy metals in vegetation in the vicinity of Myoungbong mine tailings. The results demonstrated that As, Pb and Cu concentrations and bioaccumulation factors (BCF) in seedlings of the fern (Asplenium achilleifolium) were the highest, whereas Marsh horsetail (Equisetum palustre) accumulated the highest levels of Zn. Concentrations of As, Pb, Zn and Cu in vegetable-cress (Lepidium sativum) and the edible herb-aromatic madder (Elasholtzia splendens) were higher than food safety limits. Therefore, a risk assessment of As and other heavy metals in vegetables and herbs on local human health should be conducted in the future. Show more

Keywords: arsenic, heavy metals, ferns, bioaccumulation factors

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 287-291, 2006

Authors: FENG, Xiong-han | ZU, Yan-qun | TAN, Wen-feng | LIU, Fan

Article Type: Research Article

Abstract: Oxidation of As(III) by three types of manganese oxides and the effects of pH, ion strength and tartaric acid on the oxidation were investigated by means of chemical analysis, equilibrium redox, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Three synthesized Mn oxide minerals, birnessite, cryptomelane, and hausmarnite, which widely occur in soil and sediments, could actively oxidize As(III) to As(V). However, their ability in As(III)-oxidation varied greatly depending on their structure, …composition and surface properties. Tunnel structured cryptomelane exhibited the highest ability of As(III) oxidation, followed by the layer structured birnessite and the lower oxide hausmannite. The maximum amount of As(V) produced by the oxidation was in the order (mmol/kg) ofcryptomelane (824.2) > birnessite (480.4) > hausmannite (117.9). As pH increased from the very low value (pH 2.5), the amount of As(III) oxidized by the tested Mn oxides was firstly decreased, then negatively peaked in pH 3.0–6.5, and eventually increased remarkably. Oxidation of As(III) by the Mn oxides had a buffering effects on the pH variation in the solution. It is proposed that the oxidative reaction processes between As(III) and birnessite (or cryptomelane) are as follows: (1) at lower pH condition: (MnO_2 )_x + H_3 AsO_3 + 0.5H^+ =0.5H_2 AsO_4^- +0.5HAsO_4^{2-} +Mn^{2+} +(MnO_2 )_{x-1} + H_2 O; (2) at higher pH condition: (MnO_2 )_x + H_3 AsO_3 – 0.5H_2 AsO_4 +0.5HAsO_4^{2-} +1.5H^+ + (MnO_2 )_{x-1} ·MnO. With increase of ion strength, the As(III) oxidized by bimessite and cryptomelane decreased and was negatively correlated with ion strength. However, ion strength had little influence on As(III) oxidation by the hausmannite. The presence of tartaric acid promoted oxidation of As(III) by birnessite. As for cryptomelane and hausmannite, the same effect was observed when the concentration of tartaric acid was below 4 mmol/L, otherwise the oxidized As(III) decreased. These findings are of great significance in improving our understanding of As geochemical cycling and controlling As contamination. Show more

Keywords: oxidation of As(III), As(V), Mn oxides, pH, ion strength, tartaric acid

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 292-298, 2006

Authors: FAN, Xiao-hui | SONG, Yong-sheng | LIN, De-xi | YANG, Lin-zhang | LUO, Jia-fa

Article Type: Research Article

Abstract: Ammonia volatilization loss and ^{15} N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH_4^+ -N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%–38.7% of urea applied at different stages, the greatest loss took place when urea was applied at …the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. ^{15} N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%–54.4%, and the ammonia volatilization loss was 25.4%–33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency. Show more

Keywords: ammonia volatilization, urea, ^{15}N balance, rice, influence factors, Taihu region

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 299-303, 2006

Authors: SUN, Bing-yao | TAN, Jian-zhong | WAN, Zhi-gang | GU, Fu-gen | ZHU, Ming-de

Article Type: Research Article

Abstract: To investigate the potential role of allelopathy in plant interference and in the successful invasion of alien species Solidago canadensis, aqueous and ethanolic extracts from rhizomes, stems and leaves of S. canadensis were prepared and used as treatment solutions to assess their effects on seed germination and seedling growth in four target species, mulberry (Morus alba); morning glory (Pharbitis nil), wheat (Triticum aestivum) and rape (Brassica campestris). Reduction and/or growth in germination and …growth of the target plant species in the presence of both aqueous and ethanolic extracts at different concentrations indicated that the responses were species-specific and concentration-dependent. Generally, ethanolic extracts (especially from leaves) imposed stronger effects on both seed germination and seedling growth. Extracts with lower concentration at 0.001 g/ml dw could stimulate the seedling growth of rape and morning glory, whereas extracts at any given concentrations have inhibitory effects on wheat and mulberry. It is suggested that the aqueous and ethanolic extracts of all the three parts of S. canadensis have significant allelopathic effects. Although both inhibition and stimulation occurred in the germination and growth of the target species, extracts with higher concentrations definitely inhibit seed germination and seedling growth of all target plants. We suggest that allelopathy plays a more important role than other mechanisms do in the out-competition of S. canadensis over other plants, and make it invasive in new habitats. Show more

Keywords: Canada goldenrod (Solidago canadensis L.), allelopathy, extracts, seed germination, seedling growth

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 304-309, 2006

Authors: SONG, Xue-ying | SONG, Yu-fang | SUN, Tie-heng | ZHOU, Qi-xing | ZHANG, Wei | ZHANG, Lei

Article Type: Research Article

Abstract: Five dominant bacteria strains (Acetobacter sp., Alcaligenes sp., Micrococcus sp., Arthrobacter sp. and Bacillus sp.) and five fungi strains (Cephalosporium sp. I, Cephalosporium sp. II, Aspergillus sp. I, Aspergillus sp. II and Fusarium sp.) isolated from petroleum-contaminated soil were used to assess the potential capability of mineral oil and PAH enhanced degradation separately and jointly using the batch liquid medium cultivation with diesel oil spiked at 1000 mg/L. The experiment was performed on a reciprocal shaker …in the darkness at 25°C to 30°C for 100 d. The dynamic variation in the activity of microbial inoculators in each treatment and the degradation of the target pollutants during the period of experiment were monitored. Results showed a more rapid biodegradation of mineral oil and PAHs at the beginning of the experiment (about 20 d) by dominant bacteria, fungi and their mixture than that of the indigenous microorganisms, however, thereafter an opposite trend was exhibited that the removal ratio by indigenous microorganisms was superior to any other dominant treatments and the tendency lasted till the end of the experiment, indicating the limited competitive capability of dominant microorganisms to degrade the contaminants, and the natural selection of indigenous microorganisms for use in the removal of the contaminants. At the end of the experiment, the removal ratio of mineral oil ranged from 56.8% to 79.2% and PAHs ranged from 96.8% to 99.1% in each treatment by microbial inoculators. Show more

Keywords: dominant microorganism, indigenous microorganism, mineral oil, PAHs, biodegradation

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 310-317, 2006

Authors: MASKAOUI, Khalid | HU, Zhong | ZHOU, Jun-liang | HAN, Ya-li

Article Type: Research Article

Abstract: An intensive investigation was conducted to study the distribution of polycyclic aromatic hydrocarbons (PAHs), to show firstly the level of pollution in the agricultural areas and analyses specifically the status of soil polluted by these persistent pollutants in some locations of Xiamen region. Soil samples collected from Jiulong agricultural catchment have been analysed for 16 PAH compounds, using gas chromatography flame ionization detection in order to determine the level of selected PAH components and to …identify the factors that may control their distribution and persistence in the area. The main PAHs found in soil samples were the low molecular weight. The total PAHs detected in soil samples ranged from 0.50 to 0.95μg/g soil. The highest values of PAHs were significantly detected in the orange tree leaves, which range from 236.1 to 249.3μg/g soil showing recent atmospheric inputs of these volatile pollutants. The distribution of PAHs in vegetable were monitored and indicating that the concentration were high and ranged from 8.24 to 58.87μg/g. Other sediment samples were also collected and analysed from urban sewage (5.26μg/g dw), aquacultura (0.52μg/g dw) and industrial areas (from 0.62 to 2.09μg/g dw), during this investigation. The contamination of Jiulong river estuary and Xiamen Western Sea by PAHs has been then widely justified by wastewater discharges and soil runoffs from these areas. The results, therefore, provide important information on the current contamination status caused by the atmospheric transport and point to the need for urgent actions to stop the release of these hydrocarbons to the environment. The necessity of implementing systematic monitoring of PAHs is also emphasized. Show more

Keywords: PAHs, soil, Jiulong River Estuary, Xiamen Western Sea

Citation: Journal of Environmental Sciences, vol. 18, no. 2, pp. 318-322, 2006