Journal of Environmental Sciences - Volume 18, issue 4

Authors: ZHAO, Qing-liang | LIU, Xue-yan | QI, Xu-dong | LIU, Zhi-gang

Article Type: Research Article

Abstract: Landfill leachate recirculation treatment process is a promising and economic way in northeast China due to the distinct season variation. In order to study the impact of recirculation on leachate production and its quality, two simulated sanitary landfill reactors, one with leachate recirculation and the other without, were placed outdoor in Harbin. The two-year experimental results indicated that leachate production was reduced by 86% with leachate recirculation and less or no facility for leachate treatment required. …Recirculation could improve the leachate quality dramatically with lower COD, SS, NH^4_+ -N and higher pH level. Recirculation also could enhance waste degradation and stabilization and improve the efficiency of landfill. This study confirmed that leachate recirculation was a very feasible way for on-site landfill leachate treatment in cold areas. Show more

Keywords: cold area, sanitary landfill, leachate, recirculation, solid waste

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 625-628, 2006

Authors: ZHANG, Jin | SUN, Yu-xin | HUANG, Zhi-feng | LIU, Xing-qin | MENG, Guang-yao

Article Type: Research Article

Abstract: The oily wastewater generated from pretreatment unit of electrocoating industry contains oils, phosphate, organic solvents, and surfactants. In order to improve the removal efficiencies of phosphate and oils, to mitigate the membrane fouling, coagulation for ceramic membrane microfiltration of oily wastewater was performed. The results of filtration tests show that the membrane fouling decreased and the permeate flux and quality increased with coagulation as pretreatment. At the coagulant Ca (OH)_2 …dosage of 900 mg/L, the removal efficiency of phosphate was increased from 46.4% without coagulation to 99.6%; the removal of COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was about 70% greater than that when Ca(OH)_2 was not used. The permeate obtained from coagulation and microfiltration can be reused as make-up water, and the recommended operation conditions for pilot and industrial application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5 m/s. The comparison results show that 0.2μm ZrO_2 microfilter with coagulation could be used to perform the filtration rather than conventional ultrafilter, with very substantial gain in flux and removal efficiency of phosphate. Show more

Keywords: ceramic membrane, crossflow microfiltration, coagulation, phosphate removal, fouling mitigation, phosphate-containing oily wastewater

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 629-633, 2006

Authors: WANG, Jian-ling | WANG, Bao-zhen | WANG, Lin | ZHANG, Jin-song | HUANG, Wen-zhang

Article Type: Research Article

Abstract: The concentration of suspended solids of effluent often varies in a wide range, therefore the dose of ultraviolet light (UV) in disinfection process needs to be adjusted to meet the disinfection criterion at a high frequency, and the desired disinfection effect is difficult to be ensured. The particles size and particle-associated fecal coliform (F.C.) contribution, and their influence on UV disinfection were investigated when ClO_2 and UV combined disinfection process was used. The …results showed that suspended solids content had a major impact on UV disinfection efficiency, especially the large particle size fraction. Particles (D>10μm) associated F.C. were difficult to be disinfected and were the main part of the tailings of F.C. inactivation curve. Pre-ClO_2 oxidation could reduce the number of particles in effluent, and make large particles decrease to small ones. Therefore, the influence of particles on UV disinfection could be reduced after pre-ClO_2 oxidation, and the resistance ability to particle loadings of combined process was enhanced. Moreover, the combined process has a lot of advantages, such as low toxicity, low operational/maintenance costs; it is also convenient to be established in the existing wastewater plant or the new planned one. Show more

Keywords: effluent disinfection, bio-toxicity, UV disinfection, ClO_2/UV combined disinfection

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 634-638, 2006

Authors: LI, Xin-gang | WANG, Tao | SUN, Jin-sheng | HUANG, Xin | KONG, Xiao-song

Article Type: Research Article

Abstract: Functional microorganisms to high concentration phenol containing Cr^{6+} and Pb^{2+} were cultured and biofilm was formed on polypropylene packings in bioelectro-reactor. It was found that the biodegradation capability of such biofilm to phenol changed with the applied voltage. Under the optimal electric field conditions (voltage of 3.0 V, electric field of strength 17.7 V/m and current density of 1.98 A/m^2 ), biodegradation efficiency of phenol aof concentration …of 1200 mg/L increased 33% compared to the instance without applying electric field. However, voltage had inverse effect on biodegradation, as microorganisms were killed under strong electric field. Voltage had little effect on heavy ions elimination. Higher absorption rate of Cr^{6+} and Pb^{2+} was observed when changing pH from acidic to neutral. The experiment results indicated that, after treatment, 10 L phenol of 2400 mg/L was biodegraded completely within 55 h and concentrations of Cr^{6+} and Pb^{2+} dropped to less than 1 mg/L within 12 h and 6 h, from initial values of 50 mg/L and 30 mg/L, respectively. Show more

Keywords: biofilm, biodegradation, phenol, heavy ions, electric field, reactor

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 639-643, 2006

Authors: WEI, Chao-hai | HU, Cheng-sheng | WU, Chao-fei | YAN, Bo

Article Type: Research Article

Abstract: The supercritical water gasification of phenolic wastewater without oxidant was performed to degrade pollutants and produce hydrogen-enriched gases. The simulated o-cresol wastewater was gasified at 440–650°C and 27.6 MPa in a continuous Inconel 625 reactor with the residence time of 0.42–1.25 min. The influence of the reaction temperature, residence time, pressure, catalyst, oxidant and the pollutant concentration on the gasification efficiency was investigated. Higher temperature and longer residence time enhanced the o-cresol …gasification. The TOC removal rate and hydrogen gasification rate were 90.6% and 194.6%, respectively, at the temperature of 650°C and the residence time of 0.83 min. The product gas was mainly composed of H_2 , CO_2 , CH_4 and CO, among which the total molar percentage of H_2 and CH_4 was higher than 50%. The gasification efficiency decreased with the pollutant concentration increasing. Both the catalyst and oxidant could accelerate the hydrocarbon gasification at a lower reaction temperature, in which the catalyst promoted H_2 production and the oxidant enhanced CO_2 generation. The intermediates of liquid effluents were analyzed and phenol was found to be the main composition. The results indicate that the supercritical gasification is a promising way for the treatment of hazardous organic wastewater. Show more

Keywords: supercritical water, gasification, o-cresol, hydrogen-enriched gas, wastewater treatment

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 644-649, 2006

Authors: LIU, Wen-jun | ZHANG, Yong-ji

Article Type: Research Article

Abstract: The effects of UV intensity and turbidity on selected microbial indicator inactivation were investigated. Results showed that UV disinfection was effective in killing all the selected microbial indicators, the resistance order of the microorganisms was as follows: MS-2 coliphage > Bacillus subtilis > E. coli > Staphylococcus aureus and Candida albicans. UV intensity had influence on the inactivation of all the microorganisms, high UV disinfection efficency was obtained with higher UV intensity. …Turbidity had impact on the bacteria inactivation rate, but there was no evidence that turbidity had any negative contribution to MS-2 coliphage. Under the same UV dosage, higher UV intensity could overcome the negative influence of turbidity on UV performance, enhanced microorganism inactivation effect in turbidity water. Show more

Keywords: UV disinfection, intensity, exposure time, microbial indicator

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 650-653, 2006

Authors: LI, Jun | ZHANG, Zhen-jia | LI, Zhi-rong | HUANG, Guang-yu | Abe, Naoki

Article Type: Research Article

Abstract: The distillery wastewater of Guangdong Jiujiang Distillery, which is characteristic of containing high organic matters and rich total nitrogen, was treated by a combination of methane fermentation and denitrification/nitrification processes. 80% of COD in the raw wastewater was removed by methane fermentation at the COD volumetric loading rate of 20 kg COD/(m^3 ·d) using the expanded granule sludge bed (EGSB) process. However, almost all the organic nitrogen in the raw wastewater …was converted into ammonia by ammonification there. Ammonia and volatile fatty acids (VFA) remaining in the anaerobically treated wastewater were simultaneously removed utilizing VFA as an electron donor by denitrification occurring in the other EGSB reactor and nitrification using PEG-immobilized nitrifying bacteria with recirculation process. An aerobic biological contact oxidization reactor was designed between denitrification/nitrification reactor for further COD removal. With the above treatment system, 18000–28000 mg/L of COD in raw wastewater was reduced to less than 100 mg/L. Also, ammonia in the effluent of the system was not detected and the system had a high removal rate for 900–1200 mg/L of TN in the raw wastewater, only leaving 400 mg/L of nitrate nitrogen. Show more

Keywords: ammonia, COD, VFA, methane fermentation, denitrification, nitrification, distillery wastewater, immobilized nitrifying bacteria

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 654-659, 2006

Authors: REN, Guang-meng | SUN, De-zhi | CHUNG, Jong Shik

Article Type: Research Article

Abstract: An investigation on the process of ozone combined with hydrogen peroxide and ultraviolet radiation has been carried out in order to establish the kinetics for photochemical oxidation of polyacrylamide (PAM) in aqueous solution. Effects of operating parameters, including initial PAM concentration, dosages of ozone and hydrogen peroxide, UV radiation and pH value on the photochemical oxidation of PAM, have been studied. There was an increase in photochemical oxidation rate of PAM with increasing of dosages of …O_3 , H_2 O_2 and ultraviolet radiation. Upon increasing of the initial PAM concentration, the photochemical oxidation rate of PAM decreased. Slight effect of pH value on the photochemical oxidation rate of PAM was observed in the experiments. The kinetics equation for the photochemical oxidation of PAM by the system has been established. Show more

Keywords: photochemical oxidation, polyacrylamide, kinetics, ozone/hydrogen peroxide/ultraviolet radiation

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 660-664, 2006

Authors: CUI, Li-hua | LIU, Wen | ZHU, Xi-zhen | MA, Mei | HUANG, Xi-hua | XIA, Yan-yang

Article Type: Research Article

Abstract: The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time (HRT) was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. …The average removal rates of COD (chemical oxygen demand) were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD_5 (5 d biochemical oxygen demand) removal rate in four seasons. The average removal rates of TP (total phosphorous) could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN (total nitrogen) was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality from the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells (hybrid systems) showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons. Show more

Keywords: constructed wetlands, hybrid system, horizontal-flow, vertical-flow, removal efficiency, septic tank effluent

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 665-669, 2006

Authors: LIU, Ya-nan | XUE, Gang | YU, Shui-li | ZHAO, Fang-bo

Article Type: Research Article

Abstract: Three sequencing batch reactors supplied with different carbon sources were investigated. The system supplied with glucose gained the best enhanced biological phosphorus removal although all of the three reactors were seeded from the same sludge. With the measurement of poly-β-hydroxyalkanoate (PHA) concentration, phosphorus content in sludge and extracellular exopolymers (EPS) with scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS), it was found that the biosorption effect of EPS played an …important role in phosphorus removal and that the amount of PHA at the end of anaerobic phase was not the only key factor to determine the following phosphorus removal efficiency. Show more

Keywords: biological phosphorus removal, extracellular exopolymers, biosorption

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 670-674, 2006

Authors: Tsai, Yih-jin | Kuo, Yu-chia | Chen, Tsu-chi | Chou, Feng-chih

Article Type: Research Article

Abstract: Air sparging is a remedial method for groundwater. The remedial region is similar to the air flow region in the saturated zone. If soil particles are transported during air sparging, the porosity distributions in the saturated zone change, which may alter the flow path of the air. To understand better the particle movement, this study performed a sandbox test to estimate the soil porosity change during air sparging. A clear fracture was formed and the phenomenon …of particle movement was observed when the air injection was started. The moved sand filled the porous around the fracture and the reparked sand filled the fracture, reducing the porosity around the fracture. The results obtained from the photographs of the sandbox, the current measurements and the direct sand sample measurements were close to each other and are credible. Therefore, air injection during air sparging causes sand particle movement of sand, altering the characteristic of the sand matrix and the air distribution. Show more

Keywords: air sparging, sandbox test, particle movement, current measurement

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 675-679, 2006

Authors: CHEN, Ding-jiang | LU, Jun | YUAN, Shao-feng | JIN, Shu-quan | SHEN, Ye-na

Article Type: Research Article

Abstract: Evaluation and analysis of water quality variations were performed with integrated consideration of water quality parameters, hydrological-meteorologic and anthropogenic factors in Cao-E River, Zhejiang Province of China. Cao-E River system has been polluted and the water quality of some reaches are inferior to Grade V according to National Surface Water Quality Standard of China (GB2002). However, mainly polluted indices of each tributary and mainstream are different. Total nitrogen (TN) and total phosphorus …(TP) in the water are the main polluted indices for mainstream that varies from 1.52 to 45.85 mg/L and 0.02 to 4.02 mg/L, respectively. TN is the main polluted indices for Sub-watershed I, II, IV and V (0.76 to 18.27 mg/L). BOD5 (0.36 to 289.5 mg/L), COD_{Mn} (0.47 to 78.86 mg/L), TN (0.74 to 31.09 mg/L) and TP (0 to 3.75 mg/L) are the main polluted indices for Sub-watershed III. There are tow pollution types along the river including nonpoint source pollution and point source pollution types. Remarkably temporal variations with a few spatial variations occur in nonpoint pollution type reaches (including mainstream, Sub-watershed I and II) that mainly drained by arable field and/or dispersive rural dwelling district, and the maximum pollutant concentration appears in flooding seasons. It implied that the runoff increases the pollutant concentration of the water in the nonpoint pollution type reaches. On the other hand, remarkably spatial variations occur in the point pollution type reaches (include Sub-watershed III, IV and V) and the maximum pollutant concentration appears in urban reaches. The runoff always decreases the pollutant concentration of the river water in the seriously polluted reaches that drained by industrial point sewage. But for the point pollution reaches resulted from centralized town domestic sewage pipeline and from frequent shipping and digging sands, rainfall always increased the concentration of pollutant (TN) in the river water too. Pollution controls were respectively suggested for these tow types according to different pollution causes. Show more

Keywords: spatial and temporal variations, water quality, point pollution, nonpoint pollution, Cao-E River

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 680-688, 2006

Authors: FANG, Shuan-gxi | ZHANG, Yi | MU, Yu-jing

Article Type: Research Article

Abstract: A four-dynamic-chamber system was constructed to measure NOx and NH_3 surface-exchange between a typical wheat field and the atmosphere in the Yangtze Delta, China. The average fluxes of NO, NO_2 and NH_3 were 79, −5.6 and −5.1 ngN/(m^2 ·s), and 91, −1.8 and 23 ngN/(m^2 ·s), respectively for the wheat field and the bare soil. The NO flux was positively correlated with soil temperature and the …fluxes of NO_2 and NH_3 were negatively correlated with their ambient concentrations during the investigated period. The compensation point of NO_2 between the wheat field and the atmosphere was 11.9 μg/m^3 . The emissions of NO-N and NH_3 -N from the urea applied to the wheat field were 2.3% and 0.2%, respectively, which indicated that the main pathway of N loss from the investigated winter wheat field was NO. Application of a mixture of urea and lignin increased the emissions of NO, but also greatly increased the yield of the winter wheat. Show more

Keywords: NOx, NH_3, flux, surface-exchange

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 689-700, 2006

Authors: SHEN, Zhen-xing | CAO, Jun-ji | LI, Xu-xiang | WANG, Ya-qiang | JIE, Dong-mei | ZHANG, Xiao-ye

Article Type: Research Article

Abstract: The objective of this study was to characterize the mass concentration and chemical composition of aerosol particles(PM_{2.5} ) collected at Tongliao(Inner Mongolia Autonomous Region, China), a site in Horqin Sand-land in northeast China. During spring 2005, the mass concentration for PM_{2.5} was (126 ± 71)μg/m^3 in average. Five dust storm events were monitored with higher concentration of (255 ± 77)μg/m^3 in average than the non …dusty days of (106 ± 44)μg/m^3 . Concentrations for 20 elements were obtained by the PIXE method. Mass concentrations of Al, Mg, Si, K, Ca, Ti, Mn, and V, which increased with the PM_{2.5} concentration, were higher than the pollution elements (S, Cl, Zn, Ar, Se, Br, and Pb). Enrichment factor relative to crust material was also calculated, which showed dust trace elements were mainly from earth upper crust and pollution elements were dominated the anthropogenic aerosols. The Si/Al, Ca/Al, and Fe/Al ratios in PM_{2.5} samples at Tongliao were 4.07, 0.94, and 0.82, respectively, which were remarkably different with those on other source regions, such as "Western desert source region", "North desert source region" and central Asia source. Air mass back-trajectory analysis identified three kinds of general pathways were associated with the aerosol particle transport to Tongliao, but have the similar elemental ratios, implying that elemental signatures for dust aerosol from Horqin Sand-land were different with other regions. Show more

Keywords: dust aerosol, mass concentration, elemental composition, transport pathway

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 701-707, 2006

Authors: CHEN, Ren-sheng | KANG, Er-si | JI, Xi-bin | YANG, Jian-ping | ZHANG, Zhi-hui | YANG, Yong

Article Type: Research Article

Abstract: Atmospheric CO_2 concentration (CC) near land surface and meteorological variables have been measured at four sites, named Yeniugou (alpine meadow and permafrost), Xishui (mountainous forest), Linze (oasis edge) and Ejina (lower desert), respectively, in Heihe River Basin, northwest China. The results showed that, the half hourly CC at night was larger than in daytime, and the daily averaged CC was the largest in winter. The averaged CC of 932 d at the Linze was …about 418 ppm, was about 366 ppm in the 762 d at the Ejina. In the same period from September 23 to November 9, 2004, the averaged CC was about 625, 334, 436 and 353 ppm, at Yeniugou, Xishui, Linze and Ejina, respectively. The linear relationship between daily averaged CC and air temperature T was negative, between CC and relative humidity (RH) was positive. The linear CC-atmospheric pressure (A P) relationship was negative at the Linze and Yeniugou, was positive at the Ejina. The relationship between CC and global radiation R was exponent, and soil temperature T_s was negative linear, and soil water content was complex. The correlation between CC and wind speed was not existent. Using meteorological variables together to simulate CC, could give good results. Show more

Keywords: CO_2 concentration, meteorological variables, Heihe River Basin

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 708-715, 2006

Authors: CHEN, Jing | WANG, Xue-jun | HU, Jun-dong | XU, Fu-liu | TAO, Shu

Article Type: Research Article

Abstract: In this paper, the influences of inionic surfactant Tween80 on polycyclic aromatic hydrocarbons (PAHs) sorption/desorption on artificially contaminated soil were studied, and γ model was applied to simulate the influences. Results showed that, with the use of Tween 80, the sorption behaviors of PAHs on soil altered significantly. Adsorbed Tween 80 increased the sorption amount of PAHs while the dissolved Tween80 increased the apparent solubility of PAHs. These two processes exert influences on the sorption …coefficient of PAHs in soil-water system, which can be depicted by apparent sorption coefficient. The partition coefficients (the soil/water partition coefficient of PAHs and surfactants obtained from sorption experiments) and statistical parameters used in the amended γ model were obtained in independent experiments. With these parameters, the γ model could provide a satisfactory independent prediction of PAHs release from soil to aqueous phase at two surfactant concentrations. Show more

Keywords: Tween80, PAHs, soil, sorption/desorption, γ model

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 716-720, 2006

Authors: ZHANG, Xu-hong | LIN, Ai-jun | CHEN, Bao-dong | WANG, You-shan | SMITH, Sally E | SMITH, F Andrew

Article Type: Research Article

Abstract: A glasshouse pot experiment was conducted to investigate effects of the arbuscular mycorrhizal fungus Glomus mosseae on the growth of Vicia faba and toxicity induced by heavy metals (HMs) (Cu, Zn, Pb and Cd) in a field soil contaminated by a mixture of these metals. There was also uninoculation treatment (NM) simultaneously. Mycorrhizal (GM) plants have significantly increased growth and tolerance to toxicity induced by heavy metals compared with NM plants. P uptake was significantly increased …in GM plants. Mycorrhizal symbiosis reduced the transportation of HMs from root to shoot by immobilizing HMs in the mycorrhizal, shown by increasing the ratios of HMs from root to shoot. Oxidative stress, which can induce DNA damage, is an important mechanism of heavy metal toxicity. GM treatment decreased oxidative stress by intricating antioxidative systems such as peroxidases and non-enzymic systems including soluble protein. The DNA damage induced by heavy metals was detected using comet assay, which showed DNA damage in the plants was decreased by the GM treatment. Show more

Keywords: arbuscular mycorrhizal fungi (AMF), metal contamination, metal toxicity, DNA damage

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 721-726, 2006

Authors: KE, Xin | LI, Pei-jun | ZHOU, Qi-xing | ZHANG, Yun | SUN, Tie-heng

Article Type: Research Article

Abstract: This study reports the feasibility of remediation of a heavy metal (HM) contaminated soil using tartaric acid, an environmentally-friendly extractant. Batch experiments were performed to test the factors influencing remediation of the HM contaminated soil. An empirical model was employed to describe the kinetics of HM dissolution/desorption and to predict equilibrium concentrations of HMs in soil leachate. The changes of HMs in different fractions before and after tartaric acid treatment were also investigated. …Tartaric acid solution containing HMs was regenerated by chestnut shells. Results show that utilization of tartaric acid was effective for removal of HMs from the contaminated soil, attaining 50%–60% of Cd, 40%–50% of Pb, 40%–50% of Cu and 20%–30% of Zn in the pH range of 3.5–4.0 within 24 h. Mass transfer coefficients for cadmium (Cd) and lead (Pb) were much higher than those for copper (Cu) and zinc (Zn). Sequential fractionations of treated and untreated soil samples showed that tartaric acid was effective in removing the exchangeable, carbonate fractions of Cd, Zn and Cu from the contaminated soil. The contents of Pb and Cu in Fe-Mn oxide fraciton were also significantly decreased by tartaric acid treatment. One hundred milliliters of tartaric acid solution containing HMs could be regenerated by 10 g chestnut shells in a batch reactor. Such a remediation procedure indicated that tartaric acid is a promising agent for remediation of HM contaminated soils. However, further research is needed before the method can be practically used for in situ remediation of contaminated sites Show more

Keywords: tartaric acid, soil remediation, heavy metals, soil contamination

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 727-733, 2006

Authors: WEI, Xiang-dong | ZOU, Hui-ling | CHU, Lee-min | LIAO, Bin | YE, Chang-min | LAN, Chong-yu

Article Type: Research Article

Abstract: Soil properties, microbial communities and enzyme activities were studied in soil amended with replicase (RP)-transgenic or non-transgenic papaya under field conditions. Compared with non-transgenic papaya, significant differences (P<0.05) were observed in total nitrogen in soils grown with transgenic papaya. There were also significant differences (P<0.05) in the total number of colony forming units (CFUs) of bacteria, actinomycetes and fungi between soils amended with RP-transgenic plants and non-transgenic plants. Compared with non-transgenic papaya, …the total CFUs of bacteria, actinomycetes and fungi in soil with transgenic papaya increased by 0.43–1.1, 0.21–0.80 and 0.46–0.73 times respectively. Significantly higher (P<0.05) CFUs of bacteria, actinomycetes and fungi resistant to kanamycin (Km) were obtained in soils with RP-transgenic papaya than those with non-transgenic papaya in all concentrations of Km. Higher resistance quotients for Km^r (kanam ycin resistant) bacteria, actinomycetes and fungi were found in soil planted with RP-transgenic papaya, and the resistance quotients for KTr bacteria, actinomycetes and fungi in soils with transgenic papaya increased 1.6–4.46, 0.63–2.5 and 0.75–2.30 times. RP-transgenic papaya and non-transgenic papaya produced significantly different enzyme activities in arylsulfatase (5.4–5.9x), polyphenol oxidase (0.7–1.4x), invertase (0.5–0.79x), cellulase (0.23–0.35x) and phosphodiesterase (0.16–0.2x). The former three soil enzymes appeared to be more sensitive to the transgenic papaya than the others, and could be useful parameters in assessing the effects of transgenic papaya. Transgenic papaya could alter soil chemical properties, enzyme activities and microbial communities. Show more

Keywords: transgenic papaya, soil microbes, enzyme activity, kanamycin resistance, resistance quotient

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 734-740, 2006

Authors: ZHOU, Qi-xing | ZHANG, Qian-ru | LIANG, Ji-dong

Article Type: Research Article

Abstract: Acetochlor and methamidophos are two important agrochemicals which are widely applied to agricultural production in northeast China. The investigation on the earthworm Eisenia fetida as an important type of soil animals exposed to single and binary-combined contamination of acetochlor and methamidophos was thus carried out. The single toxic effect test showed that the two agrochemicals had their toxicity to the earthworms living in phaiozem. Acetochlor had a stronger acute toxic effect on the earthworms than …methamidophos. The mortality of the earthworms exposed to individual acetochlor and methamidophos changed with an increase in the exposure time and the exposed concentrations. The LD_{50} value of acetochlor and methamidophos toxic to the earthworms was 115.6–275.3 and 29.5–228.6 mg/kg, respectively. The weight of the earthworms was a more sensitive index compared to the mortality in indicating toxic effects of acetochlor and methamidophos in phaiozem. When considering both the mortality and the body-weight change, the combined pollution of acetochlor and methamidophos in phaiozem resulted in their synergic toxic effects on the earthworms. Show more

Keywords: ecological safety, earthworm Eisenia fetida, acetochlor, methamidophos, combined pollution, soil ecotoxicology

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 741-745, 2006

Authors: XU, Xiang-hua | SHI, Ji-yan | CHEN, Ying-xu | XUE, Sheng-guo | WU, Bei | HUANG, Yu-ying

Article Type: Research Article

Abstract: Phytolacca acinosa Roxb. (P. acinosa) is a recently discovered manganese hyperaccumulator plant from southern China. It is a good candidate for phytoremediation of manganese(Mn) polluted soil for its high biomass and fast growth. Knowledge of the tissue localization and identification of heavy metals can provide essential information on metal toxicity and bioaccumulation mechanisms. Synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) microprobe was used in this study to investigate the cellular distributions of Mn …and other elements in root, stem, leaf, petiole and midrib ofP. acinosa. The highest Mn content was found in the vascular tissues of root, stem, petiole and midrib. Cortex in root played a key role in Mn absorption and Mn was limited in the vascular bundle during the process of transportation in stem. Moreover, Mn content in leaf epidermis was higher than that in mesophyll, which suggested that the sequestration of Mn in leaf epidermis might be one of the detoxification mechanisms of P. acinosa. The significance of other elemental (such as P, S, K, Ca, Fe, Zn and Cu) distribution patterns and the correlation with Mn were also discussed. Show more

Keywords: hyperaccumulator, Phytolacca acinosa Roxb., manganese, element distribution, SRXRF

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 746-751, 2006

Authors: FANG, Yun-ting | ZHU, Wei-xing | MO, Jiang-ming | ZHOU, Guo-yi | GUNDERSEN, Per

Article Type: Research Article

Abstract: Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions. Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine (Pinus massoniana) and pine-broadleaf mixed forests, both originated from the 1930's clear-cut and …pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching, and higher soil C/N ratios. Mineral soil extractable NH_4^+ -N and NO_3^- -N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH_4^+ -N in the mature forest. In contrast, inorganic N (both NH_4^+ -N and NO_3^- -N) in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%–70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region. Show more

Keywords: N deposition, N saturation, extractable inorganic N, soil solution inorganic N, subtropical China

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 752-759, 2006

Authors: FANG, Hua | YU, Yun-long | WANG, Xiao | SHAN, Min | WU, Xiao-mao | YU, Jing-quan

Article Type: Research Article

Abstract: The dissipation of chlorpyrifos in pakchoi-vegetated soil was investigated in the summer and autumn in a greenhouse and field, respectively. The dissipation of chlorpyrifos in pakchoi-grown soil was comparatively described by fitting the residue data to seven models (1st-order, 1.5th-order, 2nd-order, RF 1st-order, RF 1.5th-order, RF 2nd-order, and bi-exponential or two-compartment models). Statistical analysis was performed using the SPSS 11.5 statistical package. The bi-exponential model was selected as the optimal model according …to the coefficient of determination r^2 . The dissipation half-lives (DT_{50} ) of chlorpyrifos in pakchoi-vegetated soil at the recommended dose in the summer and autumn, calculated by the bi-exponential model, were 0.6 and 1.2 d in a greenhouse, 0.4 and 1.0 d in a field, respectively; the corresponding values at double dose were 1.2 and 2.1 d in a greenhouse, 0.5 and 1.3 d in a field, respectively. The kinetic data indicate the dissipation of chlorpyrifos in pakchoi-grown soil in a greenhouse is slower than that in a field, and dissipates slower in the autumn than in the summer. Show more

Keywords: chlorpyrifos, dissipation, greenhouse, kinetic model, soil

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 760-764, 2006

Authors: HAN, Yong-zhong | JIANG, Li-yu | CHEN, Jin-long | ZHANG, Quan-xing

Article Type: Research Article

Abstract: Thermal regeneration ofhypercrosslinked polymeric adsorbent (HPA) was performed at 67°C. Experiments were carried out using a multimode microwave oven operating at 2450 MHz and a thermostatic water bath so as to compare the effect of the different heating mechanisms on the regeneration efficiency of the HPA saturated with nitrophenols. The temperature rise action of the heterogeneous regeneration system under microwave irradiation was described. Additionally, a complete structure and chemical characterization of the …regenerated HPA was also carried out in order to study the influence of the subsequent regeneration cycles on the structure and the adsorption capacities of the adsorbents. Structure characterization of the regenerated HPA was accomplished by means of the analysis of FTIR spectra. Show more

Keywords: polymeric adsorbent, microwave irradiation, adsorption, structure

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 765-770, 2006

Authors: ZHAN, Man-jun | YANG, Xi | XIAN, Qi-ming | KONG, Ling-ren

Article Type: Research Article

Abstract: The aqueous photodegradation of bisphenol A (BPA) in the presence of Fe(III)-oxalate complexes (Fe(III)-Ox), which are common compositions of natural water, was investigated in this study. BPA underwent rapid indirect photolysis in Fe(III)-Ox solution under simulated solar irradiation, proceeding pseudo-first-order kinetics. The photolysis rate increased with decreasing pH or initial BPA level and increasing Fe(III)/oxalate concentration ratio. Hydroxyl radicals (·OH), which were generated from the photochemical processes of Fe(III)-Ox complexes and contributed …to the photooxidation of BPA, were determined by molecular probe and electron spin resonance (ESR) methods with the steady-state concentration of 2.56 × 10^{-14} mol/L. Superoxide anion radical (O_2^{&middot;-} ) was considered as the precursor of ·OH and qualitatively determined by adding nitro blue tetrazolium as well as ESR experiments. Based on the structural analysis of the intermediate photoproducts of BPA in Fe(III)-Ox complexes solution, the possible degradation pathways of BPA were proposed, involving ·OH addition, alkyl scission and alky oxidation. The results indicate that the photochemical reactivity of Fe(III) may affect the environmental fate of BPA in natural water significantly. Show more

Keywords: bisphenol A, Fe(III)-oxalate complexes, photooxidation, reactive oxygen species

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 771-776, 2006

Authors: DONG, Jun | LI, Fang-bai | LAN, Chong-yu | LIU, Cheng-shuai | LI, Xiao-min | LUAN, Tian-gang

Article Type: Research Article

Abstract: To understand the degradation of endocrine disrupting chemicals (EDCs) in natural environment with existence of iron oxides and carboxylic acids, the dependence ofbisphenol A (BPA) photodegradation on the initial concentration ofoxalate (C_{ox} ) in lepidocrocite (γ-FeOOH) aqueous suspension was investigated under both UV and visible lights in this study. Lepidocrocite powder was home-prepared by a hydrothermal process. It was found that BPA degradation was promoted greatly in the presence of oxalate …owing to the formation of lepidocrocite-oxalate complex. And there was an optimal C_{ox} , which was 2.0 and 2.4 mmol/L, under UV and visible lights, respectively. The first-order kinetic constant, k value increased 38 times from 0.17 × 10^{-2} min^{-1} in the absence of oxalate to 6.39 × 10^{-2} min^{-1} in the presence ofoxalate with an optimal C_{ox} (2.0 mmol/L) under UV irradiation, and almost 306 times from 0.02 × 10^{-2} min^{-1} in the absence ofoxalate to 6.11 × 10^{-2} min^{-1} in the presence of oxalate with an optimal C_{ox} (2.4 mmol/L) under visible irradiation. The BPA degradation rate increased and the first-order kinetic constants decreased with the increase in BPA initial concentration. The dependence of the variation of pH value, total-Fe and Fe^{2+} during the photoreaction on C_{ox} was also investigated. The pH value increased obviously with the reaction time. Total-Fe increased dramatically at the first 5 min and then decreased quickly under UV irradiation and slowly under visible irradiation. The initial concentration of oxalate is a main factor to affect BPA photodegradation in aqueous suspension under both UV and visible lights. Show more

Keywords: bisphenol A, lepidocrocite, oxalate, photodegradation

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 777-782, 2006

Authors: JIANG, Fang | ZHENG, Shou-rong | ZHENG, Zheng | XU, Zhao-yi | WANG, Yan-jin

Article Type: Research Article

Abstract: TiO_2 nanotube precursor was synthesized by the hydrothermal reaction of TiO_2 powders with NaOH solution and the properties of the nanotube materials were tuned using different post-treatments. Transmission electron microscopic (TEM) observation revealed that the nanotube could be obtained by either a direct rinse with acid solution or rinse with distilled water followed by acid solution. The results of X-ray diffraction (XRD) and inductively coupled plasma (ICP) analysis indicated that …the nanotube material was composed of H_2 Ti_2 O_5 ·H_2 . In addition, the photocaalytic activities of the resulting catalysts were found to be strongly dependent on the post-treatment. The results of the photocatalytic reaction showed that the degradation of Acid-red 3B dye fitted pseudo-zero-order kinetics and TiO_2 nanotube prepared under direct rinse with acid solution exhibited a higher catalytic efficiency compared to other catalysts. Show more

Keywords: TiO_2 nanotube, Acid-red 3B, photocatalysis, hydrothermal reaction

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 783-787, 2006

Authors: CHENG, Jin-ping | HU, Wei-xuan | LIU, Xiao-jie | ZHENG, Min | SHI, Wei | WANG, Wen-hua

Article Type: Research Article

Abstract: Wanshan mercury mine is the largest mercury deposit in Guizhou Province of China, but there were few reports on mercury toxic effect in the mining area. In order to study the neurotoxicity of food from Wanshan mercury mine area and probe into the effect of food from Wanshan mercury miner area on the changes of brain oxidative damage and expression of c-fos gene. The rats were exposed to mercury contaminated food for 20 d. The content of …malondialdehyde (MDA), superoxide dismutase (SOD), GSH-peroxidase (GSH-px) and Glutathione (GSH) in rat brain was measured, and the effect of mercury contaminated rice on the expression of c-fos mRNA in rat brain and the expression of c-FOS protein in cortex, hippocampus were observed using reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemical methods. The results showed the levels of GSH, MDA, SOD and of GSH-dependent enzymes in the rat brain changed between exposure groups and control group; The mercury polluted rice induced significantly the expression of c-fos mRNA; the c-FOS positive cells in hippocampus and cortex of exposure groups were significant different from control group (P<0.01). It could be concluded that oxidative stress signals could contribute to the induction of immediate early genes (IEGs); free radicals and their by-products might not only cause oxidative damage, but also influenced gene expression; IEGs c-fos participated in the toxicity process of brain injury by mercury polluted food. Show more

Keywords: Wanshan mercury mine, mercury polluted food, oxidative damage, c-fos

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 788-792, 2006

Authors: Lertsirisopon, Ruttapol | Soda, Satoshi | Sei, Kazunari | Ike, Michihiko | Fujita, Masanori

Article Type: Research Article

Abstract: Biodegradability of di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), di-ethylhexyl phthalate (DEHP), and di-isononyl phthalate (DINP) under an anaerobic condition was evaluated using three natural sediment microcosms obtained from ponds in Osaka, which had not been significantly polluted by the chemicals. The degradabilities of the four phthalic acid esters(PAEs)were analyzed by a first-order kinetic model with a lag phase and ranked as DBP>BBP>>DEHP>DINP. The PAEs with shorter alkyl-chains, DBP and BBP, were degraded …with quite short lag phases near to zero and short half-lives of a few days. The PAEs with longer alkyl-chains, DEHP and DINP, were degraded with lag phases of 5–30 d and the quite long half-lives of a couple of hundred days. Although no data was available on the anaerobic biodegradability of DINP before this study, it was clarified that DINP can be degraded with slow degradation rates. The fact that all the three intact sediments were capable of biodegradation of the PAEs suggests that potential of anaerobic biodegradation of PAEs is widespread in the aquatic environment. Show more

Keywords: phthalic acid esters, anaerobic biodegradation, sediment, first-order kinetics

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 793-796, 2006

Authors: Imran, Hashmi | Altaf, Khan M | Kim, Jong-Guk

Article Type: Research Article

Abstract: Popular descriptive multivariate statistical method currently employed is the principal component analyses (PCA) method. PCA is used to develop linear combinations that successively maximize the total variance of a sample where there is no known group structure. This study aimed at demonstrating the performance evaluation of pilot activated sludge treatment system by inoculating a strain of Pseudomonas capable of degrading malathion which was isolated by enrichment technique. An intensive analytical program was …followed for evaluating the efficiency of biosimulator by maintaining the dissolved oxygen (DO) concentration at 4.0 mg/L. Analyses by high performance liquid chromatographic technique revealed that 90% of malathion removal was achieved within 29 h of treatment whereas COD got reduced considerably during the treatment process and mean removal efficiency was found to be 78%. The mean pH values increased gradually during the treatment process ranging from 7.36–8.54. Similarly the mean ammonia-nitrogen (NH_3 -N) values were found to be fluctuating between 19.425–28.488 mg/L, mean nitrite-nitrogen (NO_3 -N) ranging between 1.301–2.940 mg/L and mean nitrate-nitrogen (NO_3 -N) ranging between 0.0071–0.0711 mg/L. The study revealed that inoculation of bacterial culture under laboratory conditions could be used in bioremediation of environmental pollution caused by xenobiotics. The PCA analyses showed that pH, COD, organic load and total malathion concentration were highly correlated and emerged as the variables controlling the first component, whereas dissolved oxygen, NO_3 -N and NH_3 -N govemed the second component. The third component repeated the trend exhibited by the first two components. Show more

Keywords: activated sludge system, malathion, principal component analyses (PCA), raw wastewater, removal efficiency

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 797-804, 2006

Authors: LÜ, Fan | HE, Pin-jing | SHAO, Li-ming

Article Type: Research Article

Abstract: pH and volatile fatty acids both might affect the further hydrolysis of particulate solid waste, which is the limiting-step of anaerobic digestion. To clarify the individual effects of pH and volatile fatty acids, batch experiments were conducted at fixed pH value (pH 5–9) with or without acetate (20 g/L). The hydrolysis efficiencies of carbohydrate and protein were evaluated by carbon and nitrogen content of solids, amylase activity and proteinase activity. The trend of carbohydrate hydrolysis with …pH was not affected by the addition of acetate, following the sequence of pH 7>pH 8>pH 9>pH 6>pH 5; but the inhibition of acetate (20 g/L) was obvious by 10%–60%. The evolution of residual nitrogen showed that the effect of pH on protein hydrolysis was minor, while the acetate was seriously inhibitory especially at alkali condition by 45%–100%. The relationship between the factors (pH and acetate) and the response variables was evaluated by partial least square modeling (PLS). The PLS analysis demonstrated that the hydrolysis of carbohydrate was both affected by pH and acetate, with pH the more important factor. Therefore, the inhibition by acetate on carbohydrate hydrolysis was mainly due to the corresponding decline of pH, but the presence of acetate species, while the acetate species was the absolutely important factor for the hydrolysis of protein. Show more

Keywords: inhibition, hydrolysis, pH, volatile fatty acids, partial least square

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 805-809, 2006

Authors: ZHANG, Ji-shi | SUN, Ke-wei | WU, Man-chang | ZHANG, Lei

Article Type: Research Article

Abstract: The influence of temperature on the performance of anaerobic reactors for treating the organic fraction of municipal solid waste (OFMSW) was studied. Batch digestion of OFMSW was carried out for 32 d at different temperature (25°C, 35°C, 45°C and 55°C) conditions for total solid concentrations (TS) 17% with the ratio of total organic carbon to nitrogen (C/N) being, 25:1 respectively, while keeping other parameters constant such as inoculum, start-up pH, reactor volume (2 L) and so …on. Temperature can influence the methanogenic bacteria activity, accordingly inhibiting the OFMSW biodegradation and stabilization efficiency. Anaerobic reactors excelled at TS reduction, total volatile solid reduction, chemical oxygen demand reduction, increasing cumulative biogas production, whose rate was at temperature (35°C and 55°C) conditions. Methane concentration in the biogas was above 65% in four reactors. In addition, the fluctuation of temperatures resulted in the biogas production variation. The data obtained indicated that temperature had a significant influence on anaerobic process. Show more

Keywords: municipal solid waste, anaerobic digestion, batch processing, temperature

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 810-815, 2006

Authors: ZHANG, Ming-kui | FANG, Li-ping

Article Type: Research Article

Abstract: The rapid growth and intensification of freshwater fishery can cause imbalances between phosphorus (P) input in feed and its output in produce. This aquaculture can result in enriching exogenous P in fishponds and, consequently, accelerates the process of eutrophication. To assess relations among input, accumulation, release of P and as a consequence degrading water quality in terms of chlorophyll-a (Chl-a) in freshwater fishponds, fourteen fishponds with feed supply, nine fishponds without feed supply, and five nonfish …ponds in Shaoxing Plain, southeast China were selected for comparing P accumulation in their waters and surface sediments. Surface sediment samples were collected from each pond to evaluate their total P, water soluble P, Olsen P, algal available P, and P fractions. Water samples were also collected from the ponds to measure concentrations of dissolved P and Chl-a. Total P in the sediments ranged from 0.88 to 1.73 g/kg in the fishponds with feed supply, that in the non-fish ponds ranged from 0.47 to 0.86 g/kg. Organic P, accounted for 23% to 60% of total P in the sediments, was an important P fraction and increased linearly with increasing organic matter. Long-term application of feeds resulted in increased P availability in the bottom sediments and degradation of water quality in the freshwater fishponds. Compared with non-fish ponds, sediments from the feed-supplied fishponds contained considerably higher Olsen P, algal available P, and water soluble P. Higher proportions of the labile P (NH_4 Cl-P) and potentially labile P (NaOH-IP) were also found in the sediments from the fishponds. High solubility of P in the sediments resulted in elevation of P and chlorophyl1-a concentration in the pond water. The dissolved P concentration in the pond water increased in the order of non-fish ponds (12 μg/L) < fishponds without feed supply (24 μg/L) < fishponds with feed supply (66 μg/L). Linear correlations between concentrations of total P, Olsen-P, algal available P, water-soluble P and P concentration in saturation extracts in the sediments and dissolved P in the pond water indicated that there was a buffering action of the sediment constituents on the dissolved P. Show more

Keywords: eutrophication, freshwater fishery, phosphorus fraction, water quality

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 816-821, 2006

Authors: LIU, Li-yan | JIANG, An-xi | REN, Nan-qi | JIANG, Gui-bin | LI, Yi-fan

Article Type: Research Article

Abstract: The use of technical HCH (1, 2, 3, 4, 5, 6-hexachlorocyclohexane), DDT (dichlorodiphenyltrichloroethane) and lindane in Heilongjiang River Basin (HRB) of China was studied. Between 1952 and 1984 the total usage in the HRB was 108900 t for technical HCH, and 4900 t for DDT, respectively, and the use of DDT due to dicofol application in the HRB was 220 t from 1984 to 2003. The usage of lindane in HRB was 109 t from 1991 to 2000. The results …show that the highest technical HCH use (41800 t) in HRB was on maize, accounting for 38.3% of the total usage on all crops, followed by the use on wheat (28000 t, 25.7%) and on soybean (26600 t, 24.4%). The highest DDT use (2300 t) was on soybean, accounting for 46.8% of the total usage on all crops, followed by the use on maize (1500 t, 31.3%) and on sorghum (600 t, 13.2%). The major use of lindane was mainly on wheat. Gridded usage inventories of these three OCPs (organochlorine pesticides), in HRB with a 1/6 ° latitude by 1/4 ° longitude resolution have been created by using different gridded cropland as surrogates. Some soil samples have also been collected in HRB. Data of usage and soil concentrations of Σ HCH in HRB match quite well to those in Shanghai region, and much higher soil concentration of Σ DDT in Shanghai region could be due to much heavier dicofol use in this region. Show more

Keywords: persistent organic pollutants (POPs), organochlorine pesticides (OCPs), DDT, HCH, lindane, inventories, Heilongjiang River Basin

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 822-826, 2006

Authors: ZENG, Yong | YANG, Zhi-feng | LIU, Jing-ling

Article Type: Research Article

Abstract: The weekly water quality monitor data of Liuhai lakes between April 2003 and November 2004 in Beijing City were used as an example to build an artificial neural networks (ANN) model and a multi-varieties regression model respectively for predicting the fresh water algae bloom. The different predicted abilities of the two methods in Liuhai lakes were compared. A principle analysis method was first used to select the input variables of the models to avoid the phenomenon …of collinearity in the data. The results showed that the input variables for the artificial neural networks were T, TP, transparency(SD), DO, chlorophyll-a (Chl-a),pH and the output variable was Chl-a. A three layer Levenberg-Marguardt feed forward learning algorithm in ANN was used to model the eutrophication process of Liuhai lakes. 20 nodes in hidden layer and 1 node of output for the ANN model had been optimized by trial and error method. A sensitivity analysis of the input variables was performed to evaluate their relative significance in determining the predicted values. The correlation coefficient between predicted value and observed value in all data and in test data were 0.717 and 0.816 respectively in the artificial neural networks. The stepwise regression method was used to simulate the linear relation between Chl-a and temperature, of which the correlation coefficient was 0.213. By comparing the results of the two models, it was found that neural network models were able to simulate non-linear behavior in the water eutrophication process of Liuhai lakes reasonably and could successfully estimate some extreme values from calibration and test data sets. Show more

Keywords: artificial neural networks, eutrophication, multi-varieties regression, forecast, Liuhai lakes, Beijing City

Citation: Journal of Environmental Sciences, vol. 18, no. 4, pp. 827-831, 2006