Sampling over time: developing a cost effective and precise exposure assessment program

Studies requiring ambient exposure assessments invariably ask: How often should measurements be taken? Answer to such questions is dictated by budgetary considerations as well as spatial and temporal variability in the data. For example, do we obtain measurements during all seasons, all months within seasons, weeks within months and days within weeks? On one hand, we can obtain a one-time snapshot sample and regard it as representing the "true" mean exposure. On the other hand, we may obtain a large number of measurements over time and then average these in order to represent this "true" mean exposure. The former estimate is the least expensive but may also be the least precise while the latter, may be very precise but prohibitively costly. In this paper, we demonstrate how a pilot study can be undertaken with a potentially promising and feasible sampling plan for the full-scale study. By applying the statistical methodology of variance component analysis (VCA) to the pilot study data and exploiting mathematical relationship between the variance of the overall mean exposure and posited variance components, we can develop a sampling design with decreased sampling costs and/or increased precision of the mean exposure. Our approach was applied to determine sampling design choices for an on-going study that aimed at assessing ambient particulate matter exposure. We conclude that a pilot study followed by the VCA analysis may often lead to sampling design choices that offer considerable cost savings and, at the same time, promise to provide relatively precise estimates of the mean exposure for the subsequent full-scale study.     

Autoclave and pulsed ultrasound cavitation based thermal activation of persulfate for regeneration of hydrogen titanate nanotubes as recyclable dye adsorbent

Environmental Science and Pollution Research - In the dye removal application, regeneration of hydrogen titanate nanotubes (HTN, H2Ti3O7) has been achieved via thermal activation of persulfate...     

Heat loss analysis: An approach toward the revival of parabolic dish type solar cooker

Present work investigates a noble approach toward the heat loss analysis of parabolic dish type solar cooker. Various experiments have been done on cooking pot to get the input parameter for calculation purposes. Cooking pot was kept at the focus of a parabolic dish type concentrator and repeated experiments have been done to measure solar radiation intensity (direct and Indirect) using a pyrometer, temperature at the focus of parabolic dish using a thermocouple and air velocity using hot wire anemometer to investigate the heat losses from the cooking pot. In the present article, a numerical approach has been performed to define the new parameter called performance index of the cooking pot which decides how the useful energy of working fluid inside the cooking pot approaches concentration ratio of the parabolic dish type solar cooker. The present analysis shows that the performance index varies from 15.45 to 17.66 and efficiency varies from 85.83% to 98.10% with the time of the day.     

Impact of vehicular exhaust on ambient air quality of Rohtak city, India

In the present study, ambient air quality of Rohtak city (Haryana) was monitored by High Volume Sampler. The selected parameters to judge the quality of air were Sulphur dioxide (SO2), Nitrogen dioxide NO), Ozone (O3) and Suspended particulate matters (SPM) which give a fair idea of pollution load carried by the air. The monitoring data were collected from six sites randomly selected in Rohtak city. Sulphur dioxide was found below the permissible limits of National Ambient Avo Quality Standards (NAAQS) at all the sites. Higher concentration of SO2 was observed during winter in comparison to summer and monsoon seasons. Nitrogen dioxide concentration was found to be above the prescribed standards of NAAOS at four sites in winter season. Ozone concentration was found below the prescribed standards (NAAOS), but its concentration was higher in summer season as compared to winter. Suspended particulate matter concentration was observed above the safety limits at all the sites in all three seasons.     

Impact of phosphorous on biochemical changes in Hordeum vulgare L. in mixed cropping with chickpea

Multiple cropping (i.e. intercropping or mixed cropping) plays an important role in agriculture because of the effective utilization of resources, significantly enhancing crop productivity compared with that of monocultured crops. The study was planed to assess the effect of various concentrations (00, 30, 60, 90 kg ha(-1)) of phosphorous on the biochemical composition of grains of Hordeum vulgare L. (NDB-1050) in mixed cropping system with Chickpea. Phosphorous is an essential ingredient for plants to convert atmospheric N (N2) into an ammonium (NH4) as a useable form. The available nitrogen content was found more in the year 2006 (131 kg ha(-1)) than year 2005 (105 kg ha(-1)). The results of available nitrogen content were showed that the mixed cropping system enhances N fixation process because phosphorous also influences nodule development through its basic functions in plants as an energy source. Reducing, non reducing and total sugar content of H. vulgare L. were influenced by changes in the phosphorous doses. Maximum protein (13.43%) was obtained at 60 kg P2O5 ha(-1) during the year 2006. Lysine, tryptophan and methionine content were found maximum in year 2006, respectively. Total mineral content of grains of plant (0.99 g 100g(-1)) was found maximum by the application of 60 kg P2O5 ha(-1). It is possible that there was an increase in the soil N made available by the leguminous chickpea species, and this could be another reason why there was an increase in Hordeum vulgare L. shoot mass per plant with intercropping with chickpea.     

Agricultural GHG emission and calorie intake nexus among different socioeconomic households of rural eastern India

A study was conducted to examine the interrelationships among socioeconomic factors, household consumption patterns, calorie intake and greenhouse gas emissions factors in rural eastern India based on household survey data. Findings indicated that higher monthly per capita incomes (12.1–80.1$) were associated with greater average calorie intakes (2021–2525 kcal d^?1). As estimated by the FEEDME model, in total 17.2% of the population was calorie malnourished with a regional disparity of 29.4–18.2% malnourishment. Greenhouse gas (GHG) emissions were calculated only on the basis of crop and livestock production and consumption. Rice accounted for the highest share of total GHG emissions, on average 82.6% on a production basis, which varied from 58.1% to 94.9% in regional basis. Rice contributed the greatest share (~?65% and 66.2%) in terms of both calories and GHG emissions (CO₂ eq y^?1), respectively, on a consumption basis. We conclude that extensive rice farming and increasing animal product consumption are dominant factors in the higher carbon footprint in this region and are likely to further increase with increase in per capita income. This study provides useful information to help for better crop planning and for fine-tuning food access policy, to reduce carbon footprint and calorie malnutrition.

     

Retrieval of Carbon monoxide profiles over Indian region using MOPITT data

Vertical profiles of carbon monoxide (CO) over the Indian region have scarcely been monitored. Satellite sensor, Measurement Of Pollution In The Troposphere (MOPITT) provides profiles of CO using a global retrieval scheme, which converts measured radiances to CO mixing ratios. In this study we have developed a regional retrieval scheme, valid over the Indian region, which employs Line-By-Line (LBL) calculations over a tropical model atmosphere to generate a Look-Up-Table (LUT) forward model function and uses a regional a priori dataset of CO along with seasonally variable emissivity to invert the MOPITT radiances to CO profiles. This baseline study provides an approach to optimizing retrievals for specific regional applications. A case study was carried out over a forest fire prone region in Northern India from February to April 2005 to validate the retrieval algorithm. The results are in agreement with the fire maps generated from MODerate resolution Imaging Spectro-radiometer (MODIS). The shape of the CO profiles over the region matches quite well with the vertical structure of CO during the INDOEX campaign, especially during the polluted month of April. Inter-comparisons with the MOPITT data product indicate some discrepancies in the lower troposphere, especially during the forest fire season. Future studies with in-situ measurements may be able to diagnose these disparities.