Journal of Environmental Sciences - Volume 17, issue 3

Authors: HU, Ji-ye | ZHANG, Wen-ji | LI, Jian-zhong

Article Type: Research Article

Abstract: The method of residue analysis of a new synthesized fungicide 2-allylphenol was studied by simulating the active compound structure in Gingko tree (Gingko biloba L.) and its dissipation rate and terminal residue levels in tomato under field condition. Residues of 2-allylphenol were extracted from tomato matrix with acetone, purified by liquid-liquid extraction and Florisil cartrieges, and then determined by HPLC with UV-detector. The minimum detectable amount of 2-allylphenol was 3 × 10^{-9} g, …the minimum detectable concentration of 2-allylphenol in the samples of tomato were 0.01 mg/kg. The ranges of average recoveries and coefficient variation of the method were 87.7%–90.2% and 1.25%–2.06%, respectively. The dissipation rate and terminal residue levels in tomato were determined with the method described above. The results showed that the half-life of 2-allylphenol in tomato was 6.37 d, and 2-allylphenol declined with 82.6% of the initial deposit remaining in tomato at harvest. The terminal residue levels in tomato were 0.15 mg/kg and 0.20 mg/kg following the recommended doses and time intervals. Show more

Keywords: fungicide, 2-allylphenol, residue analysis, dissipation

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 491-493, 2005

Authors: HUANG, Xiao-wu | CHENG, Wen | HU, Yong-you

Article Type: Research Article

Abstract: Screening of new microorganism being able to produce efficiently flocculants was carried out. A new model for screening efficient flocculant-producing strains was designed and tested. The results showed that this model for screening efficient flocculant-producing strains is very reliable and can greatly shorten the screening period. 13 flocculant-producing strains were isolated from activated sludge by conventional method. A strain, designated as HHE6, produced the bioflocculant with the turbidity removal 98% for kaolin …suspension. Six of 13 strains selected as the original strains were treated with NTG as mutagen, and five mutant strains (HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) with high flocculation efficiency was obtained by selection, which exhibited the flocculation rate for kaolin suspension above 90%. Strains HHE6, HHE-P7, and HHE-P24 were classified as Penicillium purpurogenum, HHE-P21 as Penicillium cyclopium, HHE-A26 as Aspergillus versicolor and HHE-A8 as Aspergillus fumigatus, and it is hitherto unreported for biofloccutant-producing strains of Penicillium. The growth of the six strains (HHE6, HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) had similar curves, i.e. firstly increasing rapidly, keeping relatively constant then and finally decreasing gradually with cultivation time. The production of bioflocculants by strains showed the similar pattern to strain growth. Show more

Keywords: bioflocculant, mutation breeding, bioflocculant-producing strains, Penicillium, Aspergillus

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 494-498, 2005

Authors: LI, Hao | MIAO, Jin-lai | CUI, Feng-xia | LIU, Xiao-guang | LI, Guang-you

Article Type: Research Article

Abstract: The effect of Ca^{2+} on the removal of Alexandrium sp. LC3 under HDTMAB stress was investigated. The results showed that the toxic effect of HDTMAB on Alexandrium sp. LC3 was significantly reduced in the presence of Ca^{2+} , especially under 4 mmol/L of Ca^{2+} . To understand the underlying mechanism, the SH group and MDA content of the cell membrane and membrane permeability were measured. It was found that the SH content …of cell member increased, the MDA content and membrane permeability decreased when Alexandrium sp. was treated with Ca^{2+} and HDTMAB complex, compared with using HDTMAB only. The data suggested that Ca^{2+} might promote HDTMAB stress resistance of Alexandrium sp. LC3 by reducing the permeability and increasing the stability of cell membrane. Show more

Keywords: Ca^{2+}, surfactant, Alexandrium sp. LC3, cell membrane permeability

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 499-502, 2005

Authors: YU, Yun-long | FANG, Hua | WANG, Xiao | YU, Jing-quan | FAN, De-fang

Article Type: Research Article

Abstract: The dissipation of chlorpyrifos on pakchoi inside and outside greenhouse was studied. The decline curve of chlorpyrifos on pakchoi could be described as first-order kinetic. The experimental data showed that both the hermetic environment of greenhouse and season affected dissipation rates of chlorpyrifos on pakchoi. Chlorpyrifos declined faster outside greenhouse than inside greenhouse. Chlorpyrifos residues at pre-harvest time were below the maximum residue limits (MRLs) fixed in China, whereas the values inside …greenhouse were higher than those outside greenhouse by almost 50%. The recommended pre-harvest time established under conditions of open field might not always fit to greenhouse production. Show more

Keywords: chlorpyrifos, residue, dissipation, pakchoi, greenhouse

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 503-505, 2005

Authors: LAN, Hui-xia | CHEN, Yuan-cai | CHEN, Zhong-hao | CHEN, Rong

Article Type: Research Article

Abstract: Cultivation of aerobic granular sludge for pentachlorophenol (PCP) degradation under microaerobic condition (DO concentration was controlled at 0.2–0.7 mg/L) was studied in this paper. Anaerobic granules were selected as inoculum. The changes of appearance were observed and the variations of SVI, VSS/TSS, PN/PS and the size of sludge were measured during cultivating. The capabilities for degradation of PCP, AOX and CODcr were also studied. Observations on mature granules were carried out by scanning electron …microscope, and the results indicated bacillus was dominant on the surface of granules while in the inner of granules both bacillus and coccus were the dominant microorganisms. K, Na, Fe, Ca, Mg, Ni, Co, Mn, Cu and Zn were detected in the granules by element analysis. Show more

Keywords: aerobic granular sludge, pentachlorophenol, microaerobic condition

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 506-510, 2005

Authors: OPARA, K.N. | FAGBEMI, B.O.

Article Type: Research Article

Abstract: To determine the factor influencing the abundance development and distribution of Simulium damnosum (S. I) immature stages in the lower Cross River Basin, Nigeria, the physico-chemical characteristics of water at breeding sites were analysed longitudinally over a 12 month period. Analysis of the water samples showed that water current correlated positively and significantly (p < 0.05), with dissolved oxygen (r = 0.95 vs 0.10); conductivity (r = 0.95 vs 0.81); hydrogen ion concentration (r = …0.03 vs 0.46); and biochemical oxygen demand (r = 0. 80 vs 0.64); from Agbokim Waterfalls and Afi River respectively. The result indicates that these parameters and Iow ionic concentration are the most essential requirement for the development of S. damnosum pre-imaginal stages. Amplitudes of annual variability as measured by co-efficient of variation varied between the parameters. From the trends in hydrological variables it was deduced that the integrated impact of precipitation, input of surface runoff and municipal effluents played an overriding role in determining the absolute levels and temporal pattern in the water quality attributes. Of the 3578 pre-imaginal stages of S. damnosum collected, 52.52% and 47.4% were collected from Agbokim Waterfall and Afl River respectively. There was a significant difference (p < 0.05) in the number of pre-imaginal stages collected from both sites. The highest number of pre-imaginal stages of S. damnosum collected were at the peak of rain (July-September) indicating that S. damnosum in the River Basin is a wet season breeder. The need for long term laboratory colonization of blackfly immature stages becomes imperative especially how these parameters could be exploited in control programme through the testing of larvicides without adverse ecological damage to the aquatic habitat. Show more

Keywords: blackflies, Simulium damnosum physico-chemical parameters, lower Cross River Basin, Nigeria

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 511-517, 2005

Authors: WANG, Li-gang | CHEN, Chang-he | Kolker, Kruse H.

Article Type: Research Article

Abstract: The adsorption capacity for vapor-phase elemental mercury (Hg^0 ) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At Iow mercury concentrations (< 200 μg/m^3 ), unburned carbon had higher adsorption capacity than commercial activated carbon. The adsorbality of unburned carbon was also found to be source dependent. Isotherms of FS carbon (separated from fly ash of …a power plant of Shishi in Fujian Province) were similar to those classified as type II. Isotherms of XJ carbon (separated from fly ash of a power plant of Jingcheng in Shanxi Province) were more like those classified as type III. Due to the relatively Iow production costs, these residual carbons would likely be considerably more costeffective for the full-scale removal of mercury from combustion flue gases than other technology. Show more

Keywords: mercury, adsorption, residual carbon, fly ash, activated carbon

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 518-520, 2005

Authors: LIU, Jing-shuang | YU, Jun-bao

Article Type: Research Article

Abstract: Element cycling in the dominant plant communities including Rh. aureum, Rh. redowskianum and Vaccinium uliginosum in the Alpine tundra zone of Changbai Mountains in northeast China was studied. The results indicate that the amount of elements from litter decomposition was less than that of the plant uptake from soil, but that from plant uptake was higher than that in soil with mineralization process released. On the other hand, in the open system including precipitation input and …soil leaching output, because of great number of elements from precipitation into the open system, the element cycling (except N, P) in the Alpine tundra ecosystem was in a dynamic balance. In this study, it was also found that different organ of plants had significant difference in accumulating elements. Ca, Mg, P and N were accumulated more obviously in leaves, while Fe was in roots. The degree of concentration of elements in different tissues of the same organ of the plants also was different, a higher concentration of Ca, Mg, P and N in mesophyll than in nerve but Fe was in a reversed order. The phenomenon indicates (1) a variety of biochemical functions of different elements, (2) the elements in mesophyll were with a shorter turnover period than those in nerve or fibre, but higher utilization rate for plant. Therefore, this study implies the significance of keeping element dynamic balance in the alpine tundra ecosystem of Changbai Mountains. Show more

Keywords: element cycling, ecosystem, dominant plant community, alpine tundra zone, Changbai Mountains

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 521-525, 2005

Authors: LI, Pei-jun | YIN, Pei-jie | ZHOU, Qi-xing | SHI, Xing-qun | XIONG, Xian-zhe

Article Type: Research Article

Abstract: The phytotoxicity of chlorobenzoic acids (CBAs) was studied and the biochemical endpoints' suitability and sensibility was evaluated. Two terrestrial plant species in the same family were exposed to different concentrations of CBAS and tested their germination according to the guideline of Organization for Economic Cooperation and Development (OECP, 1984). The results showed that CBA dose-inhibition rate of classical endpoint had the distinct linear relationship in the range of 10%–50% inhibition rate for …root elongation (p < 0.01), and the dose variances of CBAs had the greater influence on the inhibition rate of germination than on inhibition rate of root elongation. The CBA dose half effect concentration-inhibition rate of two antioxidant enzyme activity superoxide dismutase (SOD) and catalase (CAT) had the quadratic relationship, and CBA dose-inhibition rate of the peroxides (POD) activity had the linear relationship (p <0.05). Comparing the half effect concentration (EC_{50} ) of two kinds of endpoints, the POD activity was more sensitive than classical endpoint, however, SOD and CAT activity were not sensitive in the experiment. Show more

Keywords: inhibition rate, antioxidant enzyme, half effect concentration (EC_{50}), sensibility

Citation: Journal of Environmental Sciences, vol. 17, no. 3, pp. 526-528, 2005