A simple, rapid, and reproducible method is described employing solid phase extraction(SPE) using dichloromethane followed by gas chromatography(GC) with flame ionization detection(FID) for determination of volatile ...A simple, rapid, and reproducible method is described employing solid phase extraction(SPE) using dichloromethane followed by gas chromatography(GC) with flame ionization detection(FID) for determination of volatile organic compound(VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene(BTEXC) in the sample collected from the surface or 15 cm depth of water. Two hundred ml of n hexane pretreated and filtered water samples were applied directly to a C 18 SPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0 104 to 0 372 μg/ml. The highest concentration of benzene was found as 0 372 μg/ml with a relative standard deviation(RSD) of 6 2%, and cumene was not detected. Factors influencing SPE e.g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C 18 adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water. Average recoveries exceeding 90% could be achieved for cumene at 4℃ with a 2 7% RSD.展开更多
Aerobic rice （Oryza sativa L.） cultivation is considered an alternative production system to combat increased water scarcity and arsenic （As） contamination in the food chain. Pot experiments were conducted at the ...Aerobic rice （Oryza sativa L.） cultivation is considered an alternative production system to combat increased water scarcity and arsenic （As） contamination in the food chain. Pot experiments were conducted at the Wheat Research Centre, Dinajpur, Bangladesh to examine the role of water management （WM）, As and phosphorus （P） on yield and yield attributes of boro （variety BRRI dhan 29） and aman （variety BRRI dhan 32） rice. A total of 18 treatment combinations of the three levels of As （0, 20 and 40 mg/kg） and P （0, 12.5 and 25.0 mg/kg） and two WM strategies （aerobic and anaerobic） were investigated. Yield attributes were significantly affected by increasing As levels. Grain yields of BRRI dhan 29 and BRRI dhan 32 were reduced from 63.0 to 7.7 and 35.0 to 16.5 g/pot with increasing As application, respectively, indicating a greater sensitivity of BRRI dhan 29 than BRRI dhan 32. Moreover, As toxicity was reduced with aerobic compared to anaerobic WM for all P levels. During early growth stages, phytotoxic symptoms appeared on BRRI dhan 29 and BRRI dhan 32 rice stems with increasing As levels without applying P under anaerobic WM. Under anaerobic and As-contaminated conditions, BRRI dhan 29 was highly susceptible to straighthead, which dramatically reduced grain yields. There were significant relationships between the number of effective tillers per pot and root dry weight, grain yield, and number of fertile and unfertile grains per pot for both BRRI dhan 29 and BRRI dhan 32 （P＆lt;0.001）. Our findings indicate that rice could be grown aerobically in As-contaminated areas with a reduced risk of As toxicity and yield loss.展开更多
文摘A simple, rapid, and reproducible method is described employing solid phase extraction(SPE) using dichloromethane followed by gas chromatography(GC) with flame ionization detection(FID) for determination of volatile organic compound(VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene(BTEXC) in the sample collected from the surface or 15 cm depth of water. Two hundred ml of n hexane pretreated and filtered water samples were applied directly to a C 18 SPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0 104 to 0 372 μg/ml. The highest concentration of benzene was found as 0 372 μg/ml with a relative standard deviation(RSD) of 6 2%, and cumene was not detected. Factors influencing SPE e.g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C 18 adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water. Average recoveries exceeding 90% could be achieved for cumene at 4℃ with a 2 7% RSD.
基金USAID funded subproject on Impact of Arsenic Contamination on Agricultural Sustainability and Food Quality(Main USAID Grant No.388-G-00-02-00070-00)
文摘Aerobic rice （Oryza sativa L.） cultivation is considered an alternative production system to combat increased water scarcity and arsenic （As） contamination in the food chain. Pot experiments were conducted at the Wheat Research Centre, Dinajpur, Bangladesh to examine the role of water management （WM）, As and phosphorus （P） on yield and yield attributes of boro （variety BRRI dhan 29） and aman （variety BRRI dhan 32） rice. A total of 18 treatment combinations of the three levels of As （0, 20 and 40 mg/kg） and P （0, 12.5 and 25.0 mg/kg） and two WM strategies （aerobic and anaerobic） were investigated. Yield attributes were significantly affected by increasing As levels. Grain yields of BRRI dhan 29 and BRRI dhan 32 were reduced from 63.0 to 7.7 and 35.0 to 16.5 g/pot with increasing As application, respectively, indicating a greater sensitivity of BRRI dhan 29 than BRRI dhan 32. Moreover, As toxicity was reduced with aerobic compared to anaerobic WM for all P levels. During early growth stages, phytotoxic symptoms appeared on BRRI dhan 29 and BRRI dhan 32 rice stems with increasing As levels without applying P under anaerobic WM. Under anaerobic and As-contaminated conditions, BRRI dhan 29 was highly susceptible to straighthead, which dramatically reduced grain yields. There were significant relationships between the number of effective tillers per pot and root dry weight, grain yield, and number of fertile and unfertile grains per pot for both BRRI dhan 29 and BRRI dhan 32 （P＆lt;0.001）. Our findings indicate that rice could be grown aerobically in As-contaminated areas with a reduced risk of As toxicity and yield loss.
