Raj Singhvi

Field portable XRF analysis of environmental samples

One of the critical factors for successfully conducting contamination characterization, removal, and remedial operations at hazardous waste sites is rapid and appropriate response to analyze samples in a timely fashion. Turnaround time associated with off-site analysis is often too slow to support efficient utilization of the data. Field portable X-ray fluorescence (FPXRF) techniques provide viable and effective analytical approaches to meet on-site analysis needs for many types of environmental samples. Applications include the in situ analysis of metals in soils and sediments, thin films/particulates, and lead in paint.

Characteristics of polycyclic aromatic hydrocarbons in indoor and outdoor atmosphere in the North central part of India

Twenty-three polycyclic aromatic hydrocarbons (PAHs) were measured simultaneously in indoor and outdoor environment of ten homes at urban and roadside sites in the north central part of India during winter season (November 2006 to February 2007). The average concentration of total PAH (TPAH) was 1946.84 ng/m(3) in kitchen, 1666.78 ng/m(3) in living room and 1212.57 ng/m(3) in outdoors at urban site, whereas at roadside site it was 2824.87 ng/m(3), 2161.26 ng/m(3)(,) and 3294.28 ng/m(3) in kitchen, living room and outdoors respectively. The two, three and four ring PAHs were predominant in vapour phase, while the five, six ring PAHs were primarily associated with the particulate phase. The concentration trends of the PAHs in present study were naphthalene>2-methylnaphthalene>1-methylnaphthalene>biphenyl>acenaphthylene in indoor and outdoor environment of both the sites. The spatial trend of total PAHs concentrations in the house located at urban sites, was kitchen>living room>outdoors whereas at roadside site, the trend was outdoors>kitchen>living room. Correlation analysis has been used to identify the sources of PAHs. The correlation between CO(2) and ratio of living room/outdoors (L/O) and kitchen/outdoor (K/O) of total PAHs concentration for two sites was found to be significant.

Determination of Total Metallic Mercury in Compact Fluorescent Lamps (CFLs)

The United States Environmental Protection Agency/Environmental Response Team (US EPA/ERT), in conjunction with St. Johns College, Dr B R Ambedkar University, Agra, India, is conducting a study to determine mercury vapor emission rates resulting from broken compact fluorescent lamps (CFLs) in a residential setting. The overall objectives of the study are to obtain a mercury emission model and provide a homeowner with cleanup procedures and disposal options for broken CFLs. An important component in achieving these objectives is the determination of the total mercury content in CFLs for the selection of bulbs to be used in the emission study. Most of the currently available CFLs in the United States (U.S.) market are manufactured in China for U.S. companies. Several different types of CFLs were purchased from local stores and the cap and electronic parts were removed without breaking the bulb. The bulb was then placed into a 2-L polypropylene bottle containing glass stoppers or glass marbles in a mixture of nitric acid and bromine monochloride solution (BrCl). The mixture was shaken to break the lamp and allow the mercury to be completely absorbed by the BrCl. The digested samples were analyzed for mercury using standard cold vapor atomic absorption (CVAA) methods. This CFL preparation method provides excellent results for laboratory control samples (typically, 90%–110% recovery) and good repeatability for CFL bulb analyses. The sampling and analysis phases of this study are discussed in this paper.

Comparison of field and laboratory methods for monitoring metallic mercury vapor in indoor air

Real-time metallic mercury vapor levels of the indoor air were monitored at several mercury spill sites around the US in order to evaluate the effectiveness of site cleanup operations. Mercury readings taken in the field with a Jerome 431 Mercury Vapor Analyzer were compared with laboratory analysis using a modified National Institute for Occupational Safety and Health (NIOSH) 6009 method. Statistical evaluation showed that the data were highly comparable except at low concentrations, due to the large degree of uncertainty associated with measuring low levels of mercury with the Jerome analyzer. Regression analysis indicated that Jerome measurements of 10 microg/m(3) or greater are comparable for field analysis of mercury vapor in air.

Final Evaluation of US EPA Method 3546: Microwave Extraction, a Microwave-Assisted Process (MAPTM)∗ Method for the Extraction of Contaminants Under Closed-Vessel Conditions

Microwave-assisted extraction, a MAPTM technology, has been the subject of enhanced interest from the environmental sector in the last few years as a result of the need for methodologies that improve sample preparation without compromising the quality of the data while being environmentally sustainable. Liquid-phase microwave-assisted extraction offers such advantages: it is a very fast extraction technique, it consumes less solvent and energy, and it is cost effective. A preliminary validation study involving closed-vessel apparatus and contaminants such as PAHs, PCDDs/PCDFs, chlorinated pesticides, and PCBs was performed (Li et al., 1996). Excellent performance and precision were achieved for these analytes (Li et al., 1996). In order to fully evaluate the method for a wider range of analytes an interlaboratory study was performed. A round-robin study was performed with five laboratories carrying out the extraction portion. This study also involved thermally labile and potentially reactive RCRA target analytes such as phenols, phenoxyacid herbicides, and organophospho-rus pesticides. Three split samples were used by each laboratory using methodologies stipulated in a single standard operational procedure (SOP). The extractions from the five laboratories were sent to a single laboratory who performed all the analyses in order to minimize the variability of the results due to the determinative procedure. Clean up was performed using standard procedures and analyses were done according to the appropriate US EPA SW-846 methods. The broad range of applicability, the reduced sample preparation time, and the reduced amount of solvent used all contribute to achieving sustainable environmental protection goals. Furthermore, the reduced operational costs associated with the protocol — compared to conventional Soxhlet, for example — are significant and prove valuable in these times where the “greening” of the laboratory usually gives rise to higher operating costs. Further work involving open-vessel apparatus is under way.

Hg Vapor Emission from Broken Compact Fluorescent Lamps (CFLs) in an Acrylic Chamber

The United States Environmental Protection Agency/Environmental Response Team (US EPA/ERT), in collaboration with St. Johns College, Dr. B. R. Ambedkar University, Agra, India, is conducting a study to determine Hg vapor emission rates resulting from broken compact fluorescent lamps (CFLs) in a residential setting. The overall objectives of the study are to determine Hg vapor emission data and provide homeowners with cleanup procedures and disposal options for broken CFLs. Most of the currently available CFLs in the US market are manufactured in China for US companies. Several different types of CFLs were purchased from local stores and their Hg content was determined. Based on previous studies, such as the 2011 study by Singhvi and colleagues, five popular spiral CFLs were selected for emission studies in an acrylic chamber. This study found that Hg vapor emissions from CFLs may be significantly greater than those from beads of liquid Hg with weights comparable to the Hg content of the CFLs. The average 24-hour Hg loss into the atmosphere from CFLs broken on a plastic surface ranged from 0.6% to 22% of the bulb content, while that for CFLs broken on carpet ranged from 2.6% to 28%. Projections for a 12 foot × 9.33 foot × 8 foot (25.4 m3) room based on the chamber measurements in this study indicate that CFL breakage in some household settings may produce 24-hour Hg concentrations above the 2000 Agency for Toxic Substances and Disease Registry (ATSDR) minimum risk level (MRL) of 0.2 μg/m3, for typical air exchange rates. This study also indicates that Hg emission may not be proportional to exposed surface area based on experiments using liquid Hg with different surface areas.

Exposure levels and health risk assessment of ambient BTX at urban and rural environments of a terai region of northern India

Benzene, toluene and xylene (BTX) belong to an important group of aromatic volatile organic compounds (VOCs) that are usually emitted from various sources. BTX play a vital role in the tropospheric chemistry as well as pose health hazard to human beings. Thus, an investigation of ambient benzene, toluene and xylene (BTX) was conducted at urban and rural sites of Gorakhpur for a span of one year in order to ascertain the contamination levels. The sampling of BTX was performed by using a low-flow SKC Model 220 sampling pump equipped with activated coconut shell charcoal tubes with a flow rate of 250 ml/min for 20-24 h. The analysis was in accordance with NIOSH method 1501. The efficiency of pump was checked weekly using regulated rotameters with an accuracy of ±1%. The samples were extracted with CS2 with occasional agitation and analyzed by GC-FID. The total BTX concentration ranged from 3.4 μg m-3 to 45.4 μg m-3 with mean value 30.95 μg m-3 and median 24.8 μg m-3. The mean concentration of total BTX was maximum during winter (39.3 μg m-3), followed by summer (28.4 μg m-3) and monsoon season (25.1 μg m-3). The mean concentration of BTX at urban site (11.8 μg m-3) was higher than that at rural site (8.8 μg m-3). At both the sites, T/B and X/B ratios were highest in monsoon and lowest in winters. Toluene against benzene plot shows R2 value of 0.96 and 0.49 at urban and rural sites respectively. Higher R2 value at urban site clearly indicates similar sources of emission for benzene and toluene. At both the sites, the estimated integrated lifetime cancer risk (ILTCR) for benzene exceeded the threshold value of 1E-06 whereas the individual hazard quotients (HQ) for BTX did not exceed unity at any of the sites.