Nguyen Thi Kim Oanh

Analysis of meteorology and emission in haze episode prevalence over mountain-bounded region for early warning

This study investigated the main causes of haze episodes in the northwestern Thailand to provide early warning and prediction. In an absence of emission input data required for chemical transport modeling to predict the haze, the climatological approach in combination with statistical analysis was used. An automatic meteorological classification scheme was developed using regional meteorological station data of 8years (2001-2008) which classified the prevailing synoptic patterns over Northern Thailand into 4 patterns. Pattern 2, occurring with high frequency in March, was found to associate with the highest levels of 24h PM(10) in Chiangmai, the largest city in Northern Thailand. Typical features of this pattern were the dominance of thermal lows over India, Western China and Northern Thailand with hot, dry and stagnant air in Northern Thailand. March 2007, the month with the most severe haze episode in Chiangmai, was found to have a high frequency of occurrence of pattern 2 coupled with the highest emission intensities from biomass open burning. Backward trajectories showed that, on haze episode days, air masses passed over the region of dense biomass fire hotspots before arriving at Chiangmai. A stepwise regression model was developed to predict 24h PM(10) for days of meteorology pattern 2 using February-April data of 2007-2009 and tested with 2004-2010 data. The model performed satisfactorily for the model development dataset (R(2)=87%) and test dataset (R(2)=81%), which appeared to be superior over a simple persistence regression of 24h PM(10) (R(2)=76%). Our developed model had an accuracy over 90% for the categorical forecast of PM(10)>120μg/m(3). The episode warning procedure would identify synoptic pattern 2 and predict 24h PM(10) in Chiangmai 24h in advance. This approach would be applicable for air pollution episode management in other areas with complex terrain where similar conditions exist.

An intergrated waste survey and environmental effects of COGIDO, a bleached pulp and paper mill in Vietnam, on the receiving waterbody

Abstract An integrated investigation on wastewater characterization and the environmental effects from the COGIDO pulp and paper mill in Bien Hoa Industrial Estate, Vietnam, a chlorine bleached soda integrated pulp and paper mill operating without a chemical recovery system, on the receiving water body was conducted during the rainy and dry seasons in 1993 and 1995. The pollution load from the mill was very high in terms of BOD, COD and SS (COD m : 58.7 t/d; BOD: 33.3 t/d and SS: 25.1 t/d). The effluent toxicity was determined using four toxicity tests: the green micro-alga, Selenastrum capricornutum , Microtox (marine bacteria: Photobacterium phosphoreum ), the duckweed, Lemna aequinoctialis , and fish (silver barb: Puntius gonionotus , and Tilapia: Tilapia nilotica ). Selenastrum capricornutum was the most sensitive among the tested organisms. The mill toxicity emission rate (TER) was as high as 338 610 (Selenastrum test). The bleaching-pulp and semi-chemical pulp plants which contributed the largest pollution load to the total COGIDO effluent, therefore, were targeted for abatement measures. Physico-chemical parameters as well as qualitative and quantitative aquatic organism composition for the river water were established. The BOD 5 and COD values exceeded the potable surface water standard by a factor of 2 to 4. The species diversity and abundance of the phytoplankton, zooplankton and zoobenthos were found to be lower (20–40%) than that of unpolluted rivers in Vietnam, whereas pollution-indicator species increased up to four times during the dry season 1995.

Toxicity to microtox, micro-algae and duckweed of effluents from the Bai Bang Paper Company (BAPACO), a Vietnamese bleached kraft pulp and paper mill

Toxicity of the combined effluent as well as effluents from different production units of BAPACO, a Vietnamese bleached kraft integrated pulp and paper mill, was studied using three ecotoxicological tests: Microtox, the micro-alga, Selenastrum capricornutum, and the duckweed, Lemna aequinoctialis. Physico-chemical characteristics of the effluents were also analyzed. Due to unstable operating conditions of the mill, a number of samples taken at different monitoring periods from each effluent were tested, in order to get statistically reliable ranges and averages of toxicity characteristics. For the mill combined effluent, it was found that the micro-algae were the most sensitive followed by Microtox bacteria, while duckweed was not sensitive. Microtox tests showed that the bleaching filtrate from the chlorination stage (C-stage) was the most toxic among all effluents in the mill. The combined effluent from the bleaching plant contributed the largest TEF (Toxicity Emission Factor) to the toxicity balance of the whole BAPACO combined effluent. A less-than-additive mode of toxicity was obtained. In spite of high pollution loads, e.g. BOD, COD, SS, to the Red River, the toxicity of the effluent was considered to be low. However, during periods of low river water sublethal toxic effects on the biota may be expected.

Photochemical smog modeling for assessment of potential impacts of different management strategies on air quality of the Bangkok Metropolitan Region, Thailand.

Abstract A photochemical smog model system, the Variable-Grid Urban Airshed Model/Systems Applications International Mesoscale Model (UAM-V/SAIMM), was used to investigate photochemical pollution in the Bangkok Metropolitan Region (BMR). The model system was first applied to simulate a historical photochemical smog episode of two days (January 13-14, 1997) using the 1997 anthropogenic emission database available at the Pollution Control Department and an estimated biogenic emission. The output 1-hr ozone (O3) for BMR, however, did not meet the U.S. Environmental Protection Agency suggested performance criteria. The simulated minimum and maximum O3 values in the domain were much higher than the observations. Multiple model runs with different precursor emission reduction scenarios showed that the best model performance with the simulated 1-hr O3 meeting all the criteria was obtained when the volatile organic compound (VOC) and oxides of nitrogen (NOx) emission from mobile source reduced by 50% and carbon monoxide by 20% from the original database. Various combinations of anthropogenic and biogenic emissions in Bangkok and surrounding provinces were simulated to assess the contribution of different sources to O3 pollution in the city. O3 formation in Bangkok was found to be more VOC-sensitive than NOx-sensitive. To attain the Thailand ambient air quality standard for 1-hr O3 of 100 ppb, VOC emission in BMR should be reduced by 50-60%. Management strategies considered in the scenario study consist of Stage I, Stage II vapor control, replacement of two-stroke by four-stroke motorcycles, 100% compressed natural gas bus, 100% natural gas-fired power plants, and replacement of methyltertiarybutylether by ethanol as an additive for gasoline.

Levels of Pesticides and Polychlorinated Biphenyls in Selected Homes in the Bangkok Metropolitan Region, Thailand

Past uses of hazardous chemicals in Thailand for agricultural and household purposes have resulted in their ubiquity in the environment. This study aims to characterize the levels of 41 target chemicals, including 25 organochlorine pesticides (OCP), of which 17 are persistent organic pollutant (POP) pesticides, 7 pyrethroids, and 9 polychlorinated biphenyls (PCBs) in 8 homes in the Bangkok Metropolitan Region (BMR). The study is the first of these types for Thailand, and was conducted during the dry season of 2006–2007. Samples were collected at three areas of the BMR, including urban, suburban, and rural for indoor and outdoor (I/O) air, as well as from deposits on floor surfaces. Airborne samples were taken over 24 h for both the gaseous and particulate matter phases and analyzed separately by GC‐ECD following the U.S. EPA TO‐10A method. Overall 35 out of 41 compounds were detected in the samples. The compounds were mostly detected and at higher levels in the gas phase, except for a few less volatile compounds, such as pyrethroids or DDT. Indoor air concentrations are higher than the outdoor levels for most chemicals; hence, the I/O ratios are mostly above 1.0, especially for rural homes. Among the OCPs, heptachlor was found at the highest concentrations for urban homes (5.2 ± 3.1 ng/m3 indoor and 2.6 ± 0.4 ng/m3 outdoor). PCB profiles were dominated by the lighter congeners, with the highest levels found for PCB31 (10.4 indoors in urban homes (ng/m3)). Suspended matters were found to be high indoors in the rural homes, which may be linked to high‐strength of indoor sources.

Lead distribution and its potential risk to the environment: Lesson learned from environmental monitoring of abandon mine

There are many abandon and existing mines (tin, lead and zinc) in the mountainous areas of Thailand. Toxic elements including heavy metals such as lead (Pb), cadmium (Cd) and arsenic (As) have been released and transported from the mining sites to the adjacent landscape. In Thong Pha Phum District, Kanchanaburi Province, Thailand Pb contamination in the vicinity of the mine has occurred which could lead to potential health problems in downstream communities. To better understand current status of Pb contamination and accumulation in the surrounding environment and potential health impact, surface sediment, soil and plant samples were collected seasonally from representative monitoring sites along the aquatic track or flow regime. Potential health risk was determined using hazard quotient (HQ) as an index for local inhabitants who consume rice. Environmental monitoring illustrated that Pb concentrations in the surface sediment was as high as 869.4 mg kg−1 dry weight and varied differently among stations sampled. Lead content in agricultural soil ranged between 137.8 to 613.5 mg kg−1 dry weight and was inversely proportion to the distance from the point source. Moreover Pb was transported from the point source to down hill areas. At the highly polluted monitoring stations (S1, S2, and S3), concentrations of Pb exceeded the maximum allowable concentration for Pb in agricultural soil (300 mg kg−1) by 1.7–2 times. The Pb in soil was primarily associated with Fe/Mn oxides bound fraction (46–56%) followed by the organic bound fraction (25–30%). Lead uptake by plant varied and was species dependent. However root and tuber crops like cassava (19.92 mg Pb kg−1 dry weight) and curcumin (3.25 mg Pb kg−1 dry weight) could have removed Pb from the soil which suggest growing root crops in Pb contaminated soils should be avoided. However Cd, a co-contaminant at one of monitored stations (S4) yielded rice grain with Cd exceeding the maximum allowable concentration suggesting some potential health risk (HQ = 5.34) if people consume rice grown at this station. Overall result shows a low risk associated with Pb release into the environment.

Evaluation of the Mesoscale Meteorological Model (MM5)-Community Multi-Scale Air Quality Model (CMAQ) Performance in Hindcast and Forecast of Ground-Level Ozone

Abstract This paper presents the first attempt to apply the Mesoscale Meteorological Model (MM5)-Community Multi-Scale Air Quality Model (CMAQ) model system to simulate ground-level ozone (O3) over the continental Southeast Asia (CSEA) region for both hindcast and forecast purposes. Hindcast simulation was done over the CSEA domain for two historical O3 episodes, January 26– 29, 2004 (January episode, northeast monsoon) and March 24–26, 2004 (March episode, southwest monsoon). Experimental forecast was done for next-day hourly O3 during January 2006 over the central part of Thailand (CENTHAI). Available data from 20 ambient monitoring stations in Thailand and 3 stations in Ho Chi Minh City, Vietnam, were used for the episode analysis and for the model performance evaluation. The year 2000 anthropogenic emission inventory prepared by the Center for Global and Regional Environmental Research at the University of Iowa was projected to the simulation year on the basis of the regional average economic growth rate. Hourly emission in urban areas was prepared using ambient carbon monoxide concentration as a surrogate for the emission intensity. Biogenic emissions were estimated based on data from the Global Emissions Inventory Activity. Hindcast simulations (CSEA) were performed with 0.5° ×0.5° resolution, whereas forecast simulations (CENTHAI) were done with 0.1° ×0.1° hourly emission input data. MM5-CMAQ model system performance during the selected episodes satisfactorily met U.S. Environmental Protection Agency criteria for O3 for most simulated days. The experiment forecast for next-day hourly O3 in January 2006 yielded promising results. Modeled plumes of ozone in both hindcast and forecast cases agreed with the main wind fields and extended over considerable downwind distances from large urban areas.

Integrated management strategies for brick kiln emission reduction in Vietnam: a case study

The brick manufacturing industry in Vietnam is developing rapidly to meet rising demand from construction activities. Production is mainly small‐scale and without emission control measures, and hence can bring about severe health and environmental impacts including effects on agricultural crops. In this paper, we analyse the current production situation of a brick‐making commune in Vietnam and the effects on air quality. A combination of the ‘command and control’ (such as enforcement of control devices or fuel quality standards) and ‘market‐based instruments’ (such as emission fees) would stimulate the industry to adopt cleaner production measures that would benefit both economy and the environment.

A comparative study of effluent toxicity for three chlorine-bleached pulp and paper mills in Southeast Asia

Copyright (c) 1996 Elsevier Science B.V. All rights reserved. A study on toxicity discharges from three pulp and paper mills, two in Vietnam and one in Thailand, was conducted using the Microtox method, a rapid toxicity test with the marine bioluminescent bacterium, Photobacterium phosphoreum, as the test organism. Based on the EC 50 values after 5 and 15 min of exposure, i.e. 5 min EC 50 and 15 min EC 50 , respectively, the hypochlorite bleaching stage (H-Hr effluent in the Thai mill was most toxic (EC 50 were about 0.1% of the undiluted effluentr but still comparable with corresponding data obtained for COGIDO (0.4−0.5%r. In BAPACO, toxicity of the effluent from the hypochlorite stages (H1 and H2r was much lower with the EC 50 in the range of 38−83%. The chlorination (Cr stage effluent in COGIDO with the 15 min EC 50 of 18% was less toxic while the 15 min EC 50 of this stage effluent was almost the same for both BAPACO and the Thai mill. The EC 50 of the alkali-extraction (Er stage effluent were almost in the same range in all three mills. The combined effluent from the bleaching process was the most toxic in the Thai mill (EC 50 =0.4%r, second toxic in COGIDO (8−10%r and the least toxic in BAPACO (14−24%r. TEF (toxicity emission factorsr values of this effluent show the same ranking: highest for the Thai mill (15000r followed by COGIDO with much lower TEF (1200r and the least was BAPACO (800r. A less-than-additive, i.e. antagonistic, mode of toxicity was found for the combined effluent from bleaching plants and for various other combined effluents in the three mills. The bleaching plant is the largest toxicity source in terms of TEF in BAPACO, but not in COGIDO where the discharge of black liquor is the largest contribution of toxicity. For this reason, the total toxicity discharged from COGIDO with TEF>6000 was much higher than BAPACO with TEF of 750. For the Thai mill, the TEF of the pond system effluent alone was already much higher than TEF of the other two mills. Good house-keeping and process control improvement may greatly reduce acute toxicity from the mills. Copyright

Emission of dioxins/furans and other U-POPs from test burns of non-POP pesticides in a hazardous waste incinerator

This paper presents the results of test burns for obsolete pesticides (OPs) of the permethrin group in a high temperature incinerator (HTI) in Southeast Asia. Three test burn runs were conducted, a baseline run when no OP was fed to the incinerator, and two test runs with different mixtures of OP compounds (formula 1 and 2, refer to Table 1 for detail) containing chlorine in the feeding wastes. The unintentional formed persistent organic pollutants (U-POPs) including 17 dioxins/furans, 12 dioxin-like PCBs and 12 chlorobenzenes (CBs) were monitored in all input materials and all discharges (flue gas, scrubbing liquid and solid residues). The results show relatively high levels of the U-POPs in the flue gas emission with total dioxins/furans of 4.4, 3.4, and 8.4 ng I-TEQ/m(3) in the baseline, test run 1 and test run 2, respectively, which are above international acceptable emission levels. The PCB levels in flue gas were, respectively, 0.01, 0.3 and 0.4 ng I-TEQ/m(3). The baseline thus had similar U-POPs levels with the OP test runs. In stack emission, approximately 90% of the U-POPs and 100% of CBs were present in gas phase. The emission factors, mass of pollutants per metric ton (tonne) of input waste, of U-POPs associated with fly ash (from bag house) were the highest, followed by flue gas and bottom ash while those associated with scrubbing liquid were relatively low. Among the waste input material only the black toner power contained U-POPs, but at low levels. The profiles of the dioxins/furans and PCBs in the toner waste were significantly different from that in the discharges. Despite the overall good destruction and removal efficiency of permethrin (better than 90%) the high emission of U-POPs and CBs from the test burn is of another more serious concern. To our best knowledge the findings of this study are the first of this kind for the Southeast Asia. The findings emphasize that if not properly conducted a standard destruction technology of a non-POP chemical can lead to a release of a range of more dangerous U-POPs into the environment.