Journal of Environmental Sciences - Volume 16, issue 1

Authors: XIE, Xiao-mei | LIU, Wei-ping | ABID, Subhani

Article Type: Research Article

Abstract: Rapid degradation of bensulfuron-methyl upon repeated application in paddy soils was studied. The results showed that the DT_{50} of bensulfuron-methyl was reduced from 16 d to 9 d in soil with one-year bensulfuron-methyl application. Rapid bensulfuron-methyl degradation was happened to previously untreated soil by addition 5% rapid bensuifuron-methyl adapted soil and was inhibited following pre-treatment with broad-spectrum antibiotic chloramphenicol. In bensulfuron-methyl adapted soil mineralisation of ^{14} C labeled bensulfuronmethyl …to ^{14} CO_2 occurred at a faster rate than with previously untreated soil. It was concluded that rapid bensulfuron-methyl degradation upon repeated application is probably linked to the adaptation of soil bacteria which can utilize bensulfuron-methyl as a source of carbon and energy. Show more

Keywords: bensulfuron-methyl, rapid degradation, paddy soil

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 49-52, 2004

Authors: LIU, Jun | HUANG, Zheng-hong | WANG, Zhan-sheng | KANG, Fei-yu

Article Type: Research Article

Abstract: The breakthrough adsorption behaviors of gas phase trichloroethylene in a packed bed of activated carbon fibers (ACF) were investigated. The specific surface area of the ACF was 600 m^2 /g, 1400 m^2 /g and 1600 m^2 /g, respectively, and the concentration of trichioroethylene ranged from 270 mg/m^3 to 2700 mg/m^3 . Results showed that the capacity of adsorption increased with increasing specific surface area, the relationship …between the logarithms of 10% breakthrough time and concentration was approximately linear over the experimental range, the breakthrough time decreased with increasing temperature and humidity. The breakthrough curves at different inlet concentration or different temperature can be predicted by several simple theoretical models with good agreements. Show more

Keywords: trichloroethylene, activated carbon fiber, adsorption, breakthrough curve

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 53-55, 2004

Authors: HUANG, Zhi | ZHOU, Wen | YU, Ya-juan | ZHANG, Ai-qian | HAN, Shuo-kui | WANG, Lian-sheng

Article Type: Research Article

Abstract: Enrichment of volatile organic compounds (VOC) and semi-volatility organic compounds (SVOC) in surface microlayer (SM) of three drinking water sources were studied. The enrichment factor (EFs) were 0.67 to 13.37 and 0.16 to 136, respectively. The results showed some VOC and most SVOC could enrich in SM. Some EFs of SVOC was quite high. Suspension and temperature could affect EFs of SVOC, slim wind and water movement do not destroy enrichment of organic in SM.

Keywords: surface microlayer, enrichment, GC-MS, SPE

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 56-60, 2004

Authors: LEONG, SHING TET | LAORTANAKUL, PREECHA

Article Type: Research Article

Abstract: Four environmental and biological monitoring sites were strategically established to evaluate benzene and lead exposure assessment at various traffic zones of Bangkok Metropolitan Region (BMR). Biological measurement of 48 non air-conditioned, male bus drivers was carried to study the relationship between individual exposure levels and exposure biomarkers. The study group was further subdivided into four age groups (16–25, 26–35, 36–45 and 46–55 years old) to monitor the age-related exposure effects. A total …of 12unexposed persons were deliberately chosen as the control group. Measurement of unmetobolized benzene in blood and analysis of urinary tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of benzene exposure. Measurement of lead in blood and urine is also recommended for the biological monitoring of lead exposure. During the monitoring period, benzene and lead levels at Yaowarat Road was C_6 H_6 : 42.46 ± 3.88 μg/m^3 , Pb: 0.29 ± 0.03 μg/m^3 and decreased to C_6 H_6 : 33.5 ± 1.35 μg/m^3 , Pb: O.13 ± 0.01 μg/m^3 at Phahonyothin Road. Significant difference was established between the nonsmoking exposed group and nonsmoking control group for blood benzene concentrations (P < 0.001, two-tailed, Mann-Whiteney U test). Strong correlations were also found between trans-trans-Muconic acid concentrations in post shift samples and atmospheric benzene concentrations. Similarly, good correlation between all of biomarkers and lead level in air is established from automobile emissions. The analysis revealed that among the occupational population in the urban sites, the driver groups were found to have the highest risk of benzene and lead exposures derived from automobile emission. Show more

Keywords: benzene and lead measurement, biomarkers, exposure assessment, human biomonitoring

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 61-66, 2004

Authors: HE, Sheng-bing | WANG, Bao-zhen | WANG, Lin | JIANG, Yi-feng

Article Type: Research Article

Abstract: Two runs of experiments were carried out to obtain an understanding of phosphorus release and uptake under the anaerobic condition and then the aerobic condition respectively. Under anaerobic condition, it was found that the extent of phosphorus release appeared to increase with the increase of the initial organic loading rate when the initial organic loading rate was up to 0.1 gSCOD/gMLSS. When the initial organic loading rate was higher than 0.1 gSCOD/gMLSS, the amount of phosphorus …release per unit mass of MLSS reached nearly a same stationary value, and it seemed this is not affected by organic loading rate when there is external available substrate remained. In addition, the effect of NOx-N on the phosphorus release and uptake was also investigated, it was proved that the denitrifiers has an advantage over polyphosphate accumulating bacteria in competition for organic substrate under anoxic condition. Therefore, the existence of NOx-N is disadvantageous to the phosphorus release. Based upon the above investigations, the process configuration of membrane bioreactor (MBR) in combination with anaerobic phase was proposed to enhance the removal of phosphorus in treating domestic wastewater. During the experimental period of four months, average removals of 92.50%, 84.25%, 100%, 94.09% and 85.33% were achieved for COD, TP, SS, NH_3 -N and TN respectively. Show more

Keywords: wastewater treatment, MBR, anaerobic, phosphorus removal

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 67-72, 2004

Authors: YE, Qing-fu | WU, Jian-min | SUN, Jin-he

Article Type: Research Article

Abstract: A new method for extracting the bound residue (BR) derived from ^{14} C-labeled chlorsulfuron in soils was developed, and the technique of combining LC-MS with isotope tracing method was subsequently applied to identify the composition of the ^{14} C-BR in a loamy Fluvent derived from marine deposit. The results showed that the ^{14} C-[2-amino-4-methoxyl-6-methyl-1,3,5]-triazine, ^{14{ C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine and ^{14} C-chlorsulfuron parent compound constituted the main …composition of the ^{14} C-BR derived from ^{14} C-labeled chlorsulfuron in the soil. The radioactive ratio of three compounds accounted for 39.8%, 35.4% and 17.9% of total recovered radioactivity, respectively. However, a small amount (3.6% of total recovered radioactivity) of the complex of ^{14} C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine might have existed in the ^{14} C-BR in association with an unknown soil substrate. 2-chlorobenzenesulfonamide was also detected to be one of the components of the BR. The results could well explain the mechanism of phytotoxicity caused by the BR derived from chlorsulfuron in soil. In addition, the mechanism of BR formation in soil was also discussed in details. Show more

Keywords: bound residue, chlorsulfuron, composition, identification, soil

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 73-78, 2004

Authors: DONG, De-ming | HUA, Xiu-yi | LI, Yu | JI, Liang | ZHANG, Jing-jing

Article Type: Research Article

Abstract: Pb adsorption capacities of Fe oxide, Mn oxide and organic materials in natural surface coatings (biofilms and associated minerals) collected in three lakes, two ponds and a river in Jilin Province, China and Cayuga Lake in US were studied. A novel extraction technique was employed to remove one or more component(s) from the surface coatings. Pb adsorption to surface coatings before and after extraction was performed to determine the adsorptive properties of the extracted component(s). The …statistical analysis of observed Pb adsorption was carried out using nonlinear least squares fitting (NLSF) to estimate the Pb adsorption capacity of each component of surface coatings. For each body of water, the estimated Pb adsorption capacity of Mn oxide (mol Pb/mol Mn) was significantly higher than that of Fe oxide (mol Pb/mol Fe). The value of estimated adsorption capacities of organic materials with the unit mol Pb per kg COD was similar to or less than that of Fe oxides with the unit mol Pb per mol Fe. Comparison of components of surface coatings in different waters showed that the estimated Pb adsorption capacities of components in surface coatings developed in different natural waters were different,especially for Mn oxides. Show more

Keywords: surface coatings, iron oxide, manganese oxide, organic material

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 79-85, 2004

Authors: LIU, Chun-jiang | Ilvesniemi, Hannu | Kutsch, Werner | MA, Xiang-qing | Westman, Carl J. | Kauppi, Pekka

Article Type: Research Article

Abstract: The CO_2 in the atmosphere is in contact with water vapor and rain droplets forming CO_2 ˙ H_2 O, HCO^{-}_3 and CO^{2-}_3 . Global precipitation is about 505 × 10^{15} kg/a. Based on theoretical calculation for unpolluted air and measurement observations, we estimated that 100-270 × 10^{12} gC/a are scavenged from the air by global precipitation. This roughly equals carbon …emissions from volcanic sources or 2-6 per cent of current CO_2 emissions. An inventory-based estimate on carbon removal in northwestern Europe supports the above calculation on global scale. With increasing CO_2 concentration in the air, precipitation scavenging may increase. Show more

Keywords: atmospheric CO_2, dissolution, dissociation, precipitation scavenging, rainwater

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 86-89, 2004

Authors: TIAN, Wen-hua | WEN, Xiang-hua | QIAN, Yi

Article Type: Research Article

Abstract: A pilot scale zeolite medium biological aerated filter (ZBAF) was designed and used to treat municipal wastewater. It showed that ZBAF could simultaneously remove chemical oxygen demand (COD), ammonia-N and turbidity to satisfied degree at a hydraulic retention time (HRT) of 0.95 h. Their average removal efficiencies were 73.9%, 88.4% and 96.2% with the corresponding average effluent concentrations of 43.4 mg/L, 3.5 mg/L and 3.7 NTU, respectively. These effluent items met with the water quality standard …of the treated water reused for cooling water. The COD removal volumetric loading rate increased proportionally with its applied volumetric loading rate with its maximum of 7.1 kg/(m^3 ˙ d). Ammonia-N removal loading rate also increased proportionally with its applied loading rate at HRT of longer than 0.95 h and the feasible maximum removal loading rate was 0.9 kg/(m^3 ˙ d). The COD loading rate did not affect the ammonia-N removal efficiency significantly when it was lower than 5.5 kg/(m^3 ˙ d). ZBAF has good application prospect for its low cost and high removal efficency in the futrue. Show more

Keywords: ammonia-N removal, biological aerated filter, hydraulic retention time, natural zeolite, volumetric loading rate

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 90-93, 2004

Authors: El-Shershaby, A. | Sroor, A. | Ahmed, F. | Abdel-Haleem, A.S. | Abdel, Z.

Article Type: Research Article

Abstract: The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis (NAA) technique. The samples and standard were irradiated with reactor for 4 h (in the Second Research Egyptian Reactor (Et-RR-2)) with thermal neutron flux 5.9 × 10^{13} n/(cm^2 ˙ s). The gamma-ray spectra obtained were measured for several times by means of the hyper pure germanium detection …system (HPGe). Also a solid state nuclear track detector (SSNTD) CR-39, was used to measure the emanation rate of radon for these samples. The radium concentrations were found to vary from 0.39-3.59 ppm and the emanation rates were found to vary from (0.728-5.688) × 10^{-4} kg/(m^2 ˙ s). The elemental analysis of the ceramic tiles and ceramic composites have a great importance in assigning the physical properties and in turn the quality of the material. Show more

Keywords: ceramic, neutron activation analysis (NAA), radon emanation, solid state nuclear track detector (SSNTD)

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 94-99, 2004

Authors: YANG, Jian-xin | WANG, Ru-song | FU, Hao | LIU, Jing-ru

Article Type: Research Article

Abstract: The life cycle assessment of the mobile phone housing in Motorola (China) Electronics Ltd. was carried out, in which materials flows and environmental emissions based on a basic production scheme were analyzed and assessed. In the manufacturing stage, such primary processes as polycarbonate molding and surface painting are included, whereas different surface finishing technologies like normal painting, electroplate, IMD and VDM etc. were assessed. The results showed that housing decoration plays a significant role …within the housing life cycle. The most significant environmental impact from housing production is the photochemical ozone formation potential.Environmental impacts of different decoration techniques varied widely, for example, the electroplating technique is more environmentally friendly than VDM. VDM consumes much more energy and raw material. In addition, the results of two altemative scenarios of dematerialization showed that material flow analysis and assessment is very important and valuable in selecting an environmentally friendly process. Show more

Keywords: life cycle assessment (LCA), housing production, dematerialization ,

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 100-103, 2004

Authors: CHEN, Fu-tai | PENG, Feng-xian | WU, Xiao-qing | LUAN, Zhao-kun

Article Type: Research Article

Abstract: ES-DAF, a novel DAF with Iow cost, high reliability and easy controllability, was studied. Without a costly air saturator, ESDAF consists of an ejector and a static mixer between the pressure side and suction side of the recycle rotary pump. The bubble size distribution in this novel unit was studied in detail by using a newly developed CCD imagination through a microscope. Compared with MDAF under the same saturation pressure, ES-DAF can produce smaller bubble size …and higher bubble volume concentration, especially in lower pressure. In addition, the bubble size decreases with the increase of reflux ratio or decrease of superficial air-water ratio. These results suggested that smaller bubbles will be formed when the initial number of nucleation sites increases by enhancing the turbulence intensity in the saturation system. Show more

Keywords: dissolved air flotation (DAF), bubble size distribution, air saturation system, CCD imagination

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 104-107, 2004

Authors: LIN, Qi | CHEN, Ying-xu | Plagentz, V. | Schäfer, D. | Dahmke, A.

Article Type: Research Article

Abstract: Activities at a former Chemistry Triangle in Bitterfeld, Germany, resulted in contamination of groundwater with a mixture of trichloroethylene (TCE) and monochlorobenzene (MCB). The objective of this study was to develop a barrier system, which includes an ORC (oxygen release compounds) and GAC (granular activated carbon) layer for adsorption of MCB and bioregeneration of GAC, a Fe^0 layer for chemical reductive dechlorination of TCE and other chlorinated hydrocarbon in situ. A laboratory-scale column …experiment was conducted to evaluate the feasibility of this proposed system. This experiment was performed using a series of continuous flow Teflon columns including an ORC column, a GAC column, and a Fe^0 column. Simulated MCB and TCE contaminated groundwater was pumped upflow into this system at a flow rate of 1.1 ml/min. Results showed that 17%–50% of TCE and 28%-50% of MCB were dissipated in ORC column. Chloride ion, however, was not released, which suggest the dechlorination do not happen in ORC column. In GAC column, the adsorption of contaminants on activated carbon and their induced degradation by adapted microorganisms attached to the carbon surface were observed. Due to competitive exchange processes, TCE can be desorbed by MCB in GAC column and further degraded in iron column. The completely dechlorination rate of TCE was 0.16-0.18 cm^{-1} , 1–4 magnitudes more than the formation rate of three dichloroethene isomers. Cis-DCE is the main chlorinated product, which can be cumulated in the system, not only depending on the formation rate and its decaying rate, but also the initial concentration of TCE. Show more

Keywords: groundwater remediation, permeable reactive barriers, trichloroethylene, monochlorobenzene

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 108-112, 2004

Authors: WANG, Zeng-zhang | NIU, Zhi-qing | PELKONEN, MARKKU

Article Type: Research Article

Abstract: The management of sludge-settling properties in Nordic conditions is of importance during the low temperature (spring) season because of the peak settler load. A survey was made in 10 Finnish waste water treatment plants (WWTP's) and the total extended filament length and DSVI in half of the plants exceeded the limits, which indicates sludge bulking (15 km/g SS and 150 ml/g respectively). The dominant organism was Microthrix parvicella, the abundance of which was 59.22% of total …extended filament length on average.Chemicals were tested to control the filaments, and it was found that special attention has to be paid to maintaining the nitrification at low temperature. A dosage of (H_2 O_2 -based) oxidants controlled the growth of Microthrix parvicella effectively and rapidly, whereas with the use of aluminium hydroxidechioride a 2 to 5-week period was needed to decrease the filament length. Show more

Keywords: low temperature, activated sludge, bulking, Microthrix parvicella, chemical control, nitrification

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 113-116, 2004

Authors: ZENG, Xiu-qiong | LIU, Wei-ping

Article Type: Research Article

Abstract: Mixed hydroxy-Al-Fe pillared montmorillonites with large basal spacing were successfully prepared through cation-exchanging of Na^+ – montmorillonite with mixed hydroxy-Al and hydroxy-Fe pillaring solutions made from hydrolysis of corresponding metal salts, followed by calcination to convert hydroxy-Al and hydroxy-Fe into intercalated polycations. According to XRD analysis, the basal spacing d(001) of pillared products dramatically enlarged from 12.7 å in the Na-montmorillonite to 81 å in the hydroxy-Fe-montmorillonite and 77.5 å …in mixed hydroxy-Al-Fe-montmorillonite. The N_2 BET surface areas of the pillared montmorillonites also greatly increased to more than 200 mm^2 /g as compared to about 27 m^2 /g for the Na-montmorillonite. IR analysis of hydroxy-Fe, and mixed hydroxy-Al-Fe pillared montmorillonites revealed a new absorption vibration at 1384 cm^{-1} wavelength. XRF elemental analysis data also showed a high content of Fe_2 O_3 in the hydroxy-Fe pillared montmorillonite. Show more

Keywords: hydroxy-Al, hydroxy-Fe, montmorillonite, preparation, characterization

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 117-119, 2004

Authors: GUO, Huai-cheng | ZHANG, Zhen-xing | YU, Yong

Article Type: Research Article

Abstract: Miyun Reservoir is the most important water source to Beijing City. Land-use of the basin plays a great role in the protection of water resources. Hence a sustainable land-use planning is required to optimize land-use structure and protect water resources in the basin. Based on the complete land-use system analysis in Miyun, a grey multi-objective programming to basin land-use (GMOPBLU) model was developed and applied to land-use planning. Two alternatives were produced and analyzed by means …of interactive adjustment and scenario analysis. The results showed the GMOPBLU model is a valuable approach for basin land-use planning. Show more

Keywords: system analysis, Miyun, optimization, model,

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 120-125, 2004

Authors: ZENG, Guang-ming | LIN, Yu-peng | QIN, Xiao-sheng | HUANG, Guo-he | LI, Jian-bing | JIANG, Ru

Article Type: Research Article

Abstract: A newly developed model for the optimum municipal wastewater treatment plant (MWTP) design is presented. Through introducing the interval variables, the model attempts to consider the effects of uncertainties caused by the fluctuation of the wastewater quality and quantity during the design of MWTP. The model solution procedure is illustrated in detail, and a numerical example is given to verify the feasibility and advantage of the model. Furthermore, the possibility of the model application is briefly …outlined. Show more

Keywords: uncertainty, municipal wastewater treatment plant, optimum design, model

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 126-131, 2004

Authors: Alam, Md. Zahangir | Fakhru'l-Razi, A. | Molla, Abul H.

Article Type: Research Article

Abstract: This study was undertaken to screen the filamentous fungi isolated from its relevant habitats (wastewater, sewage sludge and sludge cake) for the bioconversion of domestic wastewater sludge. A total of 35 fungal strains were tested against wastewater sludge (total suspended solids, TSS 1%–5% w/w) to evaluate its potentiality for enhancing the biodegradability and dewaterability using liquid state bioconversion (LSB) process. The strains were divided into five groups i.e. Penicillium, Aspergillus, Trichoderma, Basidiomycete and …Miscellaneous, respectively. The strains WWZP1003, SCahmA103, SCahmT105 and PC-9 among their respective groups of Penicillium,Aspergillus, Trichoderma and Basidiomycete played potential roles in terms of separation (formation of pellets/flocs/filaments), biodegradation (removal of COD) and filtration (filterability) of treated domestic wastewater sludge. The Miscellaneous group was not considered due to its unsatisfactory results as compared to the other groups. The pH value was also influenced by the microbial treatment during fermentation process. The filterability of treated sludge was improved by fungal treatment, and lowest filtration time was recorded for the strain WWZP1003 and SCahmA103 of Penicillium and Aspergillus groups respectively compared with other strains. Show more

Keywords: filamentous fungi, screening, wastewater sludge, pellets, filtration, liquid state bioconversion

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 132-137, 2004

Authors: GE, Jian | HOKAO, Kazunori

Article Type: Research Article

Abstract: Questionnaire surveys and subjective evaluations on residential environment were performed in order to grasp the main factors of residential environment of small local cities. The suitable evaluation index system was established, and the regional residential environment characteristics and personal residential preference types were analyzed, so that their influence on residential environment evaluation could be grasped. The results can be applied to the residential environment planning, construction and monitoring of local cities.

Keywords: residential environment evaluation, local city, regional characteristics, personal residential preference

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 138-144, 2004

Authors: LI, Jie | LI, Guo-feng | WU, Yan | WANG, Ning-hui | HUANG, Qiu-nan

Article Type: Research Article

Abstract: Positive DC corona discharge is formed with needle-plate electrode configuration, in which the water vapor is ejected though the needle points. The purpose is to increase the numbers of the water-based radicals, ionize the water molecule and improve the desulfuration efficiency of pulsed corona reactor. The water ions were determined by four stages molecular beam mass spectrometer and diagnose the water-based radicals by emission spectrograph. A conclusion on formation of ions and radicals with DC corona …discharges can be drawn. Show more

Keywords: DC corona, activator, desulfuration

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 145-148, 2004

Authors: KUANG, Shao-ping

Article Type: Research Article

Abstract: Preliminary study is carried out on the endocrine-disrupting organic chemicals of polychlorinated biphenyls (PCBs: PCB-28, 60,104, 153, 190) in hard roes of loaches (Misgurnus anguillicaudatas) in Weishanhu Lake, China. Results showed that the hard roes of loaches collected from the areas near the influx (such as Pengkou T-PCB = O.243 μg/g) or efflux (such as Hanzhuang T-PCB = 0.221 μg/g)are characterized by higher PCB contents, about 4 times that from the central lake (T-PCB = …0.066 μg/g), suggesting great difference between their pollutions. The PCB distributions indicated that PCB congeners with more chlorine are more easily accumulated in roes of loaches. The microscopic characteristics reveal that the PCB contents at present cannot lead the roes of loaches to be abnormal.However, the roes with higher PCBs in Pengkou and Hanzhuang are obviously bigger than those with lower PCBs (T-PCBs ⩽ 0.176 μg/g)in other localities. It is suggested that PCBs have a stronger estrogenic activity on the roes of loaches, and the phenomenon is likely premonitory for the abnormal development of the hard roes. Show more

Keywords: polychlorinated biphenyls (PCBs), environmental hormone, hard roes, loaches, Weishanhu Lake

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 149-152, 2004

Authors: ZHANG, Jian | HUANG, Xia | SHAO, Chang-fei | LIU, Chao-xiang | SHI, Han-chang | HU, Hong-ying | Liu, Zhi-qiang

Article Type: Research Article

Abstract: Influence of packing media on nitrogen removal in a subsurface infiltration system was studied. System A was filled with loamy soil and system B was filled with mixed soil of 75% red clay with 25% cinder. Both systems were fed with sewage at the same hydraulic loading of 2 cm/d at continuous operation mode. The same excellent removal performances of COD and T-P could be achieved in both infiltration systems with removal rates about 85% and 98%, …respectively. In system A, NH^+_4 -N removal rate was as high as 96.5% and TN removal rate was relatively much lower as 55.7%. And in system B, NH^+_4 -N removal rate was as Iow as 75.4% and T-N removal rate was relatively much higher as 75.5%. The difference was attributed to different soil oxidation- reduction condition that was greatly influenced by soil texture in subsurface infiltration system. Loamy soil led to oxidative condition that was favorable to nitrification and disadvantageous to denitrification. The results were just adverse to the system filled with clay. Intermittent operation was adopted to improve nitrogen removal in system B. N-H^+_4 -N removal rate could be increased to about 95% and T-N removal rate could be increased to about 90% at intermittent operation mode in system B. Analysis of nitrogen removal mechanisms indicated that nitrification-denitrification was the primary nitrogen removal path in subsurface infiltration system and crop uptake was another important nitrogen removal way. It was the key to improve the total N removal performance that a suitable packing soil was available to present favorable oxidation-reduction condition for simultaneous nitrification and denitrification. Show more

Keywords: subsurface infiltration system, nitrogen removal, oxidation-reduction potential, soil texture

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 153-156, 2004

Authors: YANG, Zhi-feng | XU, Lin-yu

Article Type: Research Article

Abstract: High concentrations of air pollutants such as total suspended particulates (TSP) and sulfur dioxide (SO_2 ) have serious impacts on nearby populations. In this paper, a survey of rural Tianjin residents' willingness-to-pay for health improvement was reported on, and the MBDC (multiple bounded discrete choice) model was adopted to study the respondents' willingness-to-pay to prevent respiratory illnesses. The results showed that the willingness-to-pay for health improvement was affected by respondents' health …condition, work situation and environmental awareness, but not by personal habits, such as smoking. If person's willingness-to-pay to avoid respiratory diseases can be considered equal to the cost to personal health caused by air pollution, the total cost will reach 538 × 10^6 RMB Yuan (RMB, equal to 65 million USD) per year. Show more

Keywords: health loss, MBDC, willingness-to-pay, TVIE, Tianjin City

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 157-160, 2004

Authors: XU, Fu-liu | LAM, K.C. | Dawson, R.W. | TAO, Shu | CHEN, Y.D.

Article Type: Research Article

Abstract: The long-term temporal and spatial dynamics of marine coastal water quality in Tolo Harbor, Hong Kong were explored. The Harbor is divided into three zones represented as Harbor, Buffer, and Channel Subzones. The time range for the study covers the period from the 1970s to the 1990s. The selected indicators for the comprehensive assessment of water quality consist of physical, chemical and biological aspects, including suspended solids (SS), Secchi disk depth (SD), 5-day biochemical oxygen demand …(BOD_5 ), total nitrogen (TN), total phosphorus (TP), faecal coliform, chlorophyll-a (Chl-a), and the number of red tide occurrences. The results indicated the presence of obvious temporal and spatial trends with regard to changes in water quality. Spatially, water quality in the Channel Subzone is the best, while that in the Harbor Subzone is the worst. On a temporal basis, the average trend from bad to good was 1980s > 1990s > 1970s as indicated by most of the selected water quality indicators. Water quality during the late 1980s reached its worst level with the lowest SD, the highest BOD_5 , TN, TP, Chl-a concentrations, and the number of red tide occurrences. These long-term temporal-spatial water quality trends were also found in other studies of the Tolo Harbor. The large quantity of pollutants produced as a result of increasing population, industrial and commercial actives, and urbanization and industrialization trends in both Shatin and Tai Po seem to be primarily responsible for the changes in marine coastal water quality. Show more

Keywords: temporal-spatial dynamics, water quality, indicators, pollution load, Tolo Harbor

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 161-166, 2004

Authors: CUI, Yu-jing | Luc, Hens | ZHU, Yong-guan | ZHAO, Jing-zhu

Article Type: Research Article

Abstract: Ecological footprint has been given much attention and widely praised as an effective heuristic and pedagogic device for presenting current total human resource use in a way that communicates easily to almost everyone since 1996 when Wackernagel and Rees proposed it as a sustainable development indicator. Ecological footprint has been improving on its calculation and still can be a benchmark to measure sustainable development although there are still ongoing debates about specific methods for calculating the …ecological footprint. This paper calculates the ecological footprint of Shandong Province, China with the methodology developed by Wackemagel and analyzes the current situation of sustainable development in Shandong. Show more

Keywords: ecological footprint, carrying capacity, sustainable development, Shandong

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 167-172, 2004

Authors: LI, Shao-shan | WANG, Yan | BJÖRN, Lars Olof

Article Type: Research Article

Abstract: DNA damage in the form of cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts (6-4PPs) induced by UV-B radiation in Arabidopsis thaliana at different temperatures was investigated using ELISA with specific monoclonal antibodies. CPDs and 6-4PPs increased during 3 h UV-B exposure, but further exposure led to decreases. Contrary to the commonly accepted view that DNA damage induced by UV-B radiation is temperature-independent because of its photochemical nature, we found UV-B-induction of CPDs and 6-4PPs in Arabidopsis …to be slower at a Iow than at a high temperature. Photorepair of CPDs at 24°C was much faster than that at 0°C and 12°C, with 50% CPDs removal during 1 h exposure to white light. Photorepair of 6-4PPs at 12°C was very slow as compared with that at 24°C, and almost no removal of 6-4 PPs was detected after 4 h exposure to white light at 0°C. There was evidence to suggest that temperaturedependent DNA damage and photorepair could have important ecological implications. Show more

Keywords: Arabidopsis thaliana, cyclobutane pyrimidine dimers (CPDs), DNA repair, (6-4) photoproducts (6-4PPs), temperature, UV-B radiation

Citation: Journal of Environmental Sciences, vol. 16, no. 1, pp. 173-176, 2004