Showing papers by "Raktim Pal published in 2007"

Experimental choices for the determination of carbonyl compounds in air.

Abstract: The analysis of carbonyls in ambient air has received a great deal of scientific attention with the advancement of analytical techniques and increased demand for the build-up of its data base. In this review article, we have attempted to provide some insight into the relative performance of different instrumental approaches available for the analysis of ambient carbonyls with a major emphasis on high performance liquid chromatographic and gas chromatographic methods. Reported in several international standard procedures, derivatization of carbonyls with 2,4-dinitrophenylhydrazine (2,4-DNPH) with either an impinger or cartridges is the most commonly used method of HPLC detection. In this respect, a number of alternative hydrazine reagents have also been discussed for use with HPLC. In contrast, GC methods based on the combined application of adsorptive enrichment on solid sorbents and thermal desorption are examined with regard to their suitability for carbonyl analysis in air. Particular emphasis has been directed towards the advantages and drawbacks of these different instrumental techniques for ambient carbonyls. Based on this comparative approach, we discuss the suitability for each method for carbonyl analysis.

Effect of novaluron on microbial biomass, respiration, and fluorescein diacetate-hydrolyzing activity in tropical soils

Abstract: The aim of this study was to assess the potential harmful effects of novaluron on soil microbiological parameters in clay loam alluvial soil (Typic udifluvent) and coastal saline soil (Typic endoaquept) under controlled laboratory tests. The applications of novaluron were made at or above the recommended rates, which includes field rate (FR), two times (2FR), and ten times (10FR) the FR. The laboratory incubation study was carried out at 60% of maximum water holding capacity of soils and at 30°C. Novaluron application rate even up to 10FR resulted in a short-lived and transitory toxic effect on soil microbial biomass C and fluorescein diacetate-hydrolyzing activity. Microbial metabolic quotient changed but for a short period. It can be concluded that novaluron had a transient and negligible harmful effect on the soil microbiological parameters studied at higher rates than those usually used in the field.

Relationship between acidity and microbiological properties in some tea soils

Abstract: The present study was conducted to investigate the effects of different forms of soil acidities on microbial biomass C, ergosterol content, microbial metabolic quotient, microbial respiration quotient, and fluorescein diacetate-hydrolyzing activity of some tea-growing soils of India. Total potential and exchangeable acidity and extractable and exchangeable aluminum were higher in Tripura followed by Jalpaiguri and Kharagpur soil. Different forms of acidity were significantly and positively correlated with each other. All the microbiological properties investigated were significantly and positively correlated with soil organic C content. The ratio of organic C with microbial parameters was significantly and negatively correlated with different forms of acidity. Principal component analysis indicated that the microbial activities were not directly affected by the extractable aluminum and total potential acidity. Although the tea soils had higher microbial biomass and activities because of higher organic matter content than other soils, the ratios of microbial parameters/organic carbon indicated that inhibition of microbial growth and activities had occurred because of acidity stress.