Indoor Air Background Levels of Volatile Organic Compounds and Air-Phase Petroleum Hydrocarbons in Office Buildings and Schools

A background indoor air study has been completed which includes the collection of indoor air samples from office buildings and schools. The anonymous study was designed with input from the U.S. Environmental Protection Agency and the Massachusetts Department of Environmental Protection. The sampling was implemented in 2013, 2014, and 2015 and included the collection of 25 school building samples and 61 office building samples. The study generated 14,668 new indoor air background data points, with samples collected from buildings located in 26 cities in 18 states, including Arizona, California, Connecticut, Indiana, Kansas, Maine, Massachusetts, Minnesota, Montana, New Hampshire, New Jersey, New York, Nevada, North Carolina, Ohio, Texas, Utah, and Washington. Indoor air background concentrations of target compound volatile organic compounds (VOCs) ranged from less than the laboratory method reporting limit of 0.044 μg/m³ to concentrations up to 1190 μg/m³, with hydrocarbon ranges from less than the reporting method limit of 10 μg/m³ to concentrations up to 3000 μg/m³. Some VOCs were identified ubiquitously in indoor air background, and some were identified at concentrations which exceeded risk-based regulatory screening levels. These study results provide useful and updated information on indoor air background and air quality in offices and schools and can be used in future regulatory guidance update considerations, for further examination of relationships between these data and residential study data, in human health risk assessments and risk communication, and in planning future studies.     

DISCRIMINANT PRINCIPAL COMPONENTS ANALYSIS

When the number of variables exceeds the number of samples, one method of multivariate discriminationis to use principal components analysis to reduce the dimensionality and then to perform canonicalvariates analysis (PC-CVA). This paper proposes an alternative approach in which discriminant analysisis carried out by a weighted principal component analysis of the group means (DPCA). This method doesnot require prior data reduction and produces discriminant factors that are orthogonal in the original dataspace. The theory and performance of the two methods are compared. Although the individual factors ofDPCA are found to be less discriminating than PC-CVA, the overall discrimination, calculated bymultivariate analysis of variance, and the predictive value, estimated by the leaving-one-out error rate,are broadly comparable.     

Identification of clusters in tropical cyclone tracks of North Indian Ocean

Tropical cyclones are a key climate-related hazard in South Asia. Assessment of the risk of cyclone impacts requires a comprehensive characterization of historical cyclone climatology. This study analyzes the tracks of tropical cyclones in the North Indian Ocean. Based on their spatial characteristics, cyclone tracks appear to be grouped into five well-defined clusters. These clusters correspond to distinct regions of cyclonic activity and exhibit differences in characteristics such as genesis location, probability of landfall, duration, and maximum intensity. Some of the identified clusters appear particularly important with regard to impacts because events in these clusters have greater landfall probability and are more intense. The clustering approach is likely to provide useful insights for the characterization of cyclone risk.     

Impact of slate quarrying on soil properties in semi-arid Mahendragarh in India

Slate quarrying in Mahendragarh district of Haryana state has resulted in changes in soil properties. Most of the mining area is devoid of vegetation. The soil in and around the mining area (0–1 km) is alkaline (pH 11.2–11.7) but non-saline (electrical conductivity < 4). The alkaline nature of the soil was attributed to the high concentrations of hydroxyl (OH⁻), carbonate (CO₃²⁻) and bicarbonate (HCO₃ ⁻) present in minerals of mined materials. Biotite, limonite, kaolinite, gibbsite, muscovite, geothite, dolomite and so on were the chief minerals added to soil through mining. The physical properties of soil, i.e. porosity, water-holding capacity (WHC), bulk density and particle density represented poor soil health in mining area (34.4, 29.8%, 1.636, 2.496 g/cc, respectively) and they improved with distance away from it (46.4, 38.3%, 1.070, 2.180 g/cc, respectively, at a distance of 1 km). Porosity and WHC were found to be a function of increased organic matter away from the mining area. CO₃²⁻, HCO₃⁻, phosphate (PO₄³⁻), lead (Pb) and iron (Fe) were more in mining area and decreased with distance. On the other hand, sodium (Na⁺), potassium (K⁺), chloride (Cl⁻), sulphate (SO₄²⁻), organic carbon, total Kjeldahl’s nitrogen, cation exchange capacity, chromium (Cr) and cadmium (Cd) increased with distance from mining area. High concentration of heavy metals in mining area was a cause of concern (0.93 μg/g Cd, 22.35 μg/g Cr, 26.25 μg/g Pb, 1,383.75 μg/g Fe). The change in physico-chemical properties could be because of the addition of chemical constituents that are a part of major minerals present in mined material. The soil away from mining area represented comparatively better properties.     

Relative role of sea surface temperature and snow on Indian summer monsoon seasonal simulation using a GCM

Indian summer monsoon is a global scale phenomenon controlled by different land, ocean, and atmospheric parameters. Sea surface temperature (SST) and snow are two of the major parameters, which may alter the spatial and temporal patterns of circulation and rainfall during Indian summer monsoon. In the current paper, we study the monsoon variability using long integrations (20 years) of the Indian Institute of Technology Delhi (IITD) Spectral model at T80L18 resolution with observed and climatological SST and snow. Study shows response of IITD GCM in simulating the Indian summer monsoon rainfall and circulation relative to the snow and SST as boundary conditions. The model’s response to SST and snow is examined by conducting four types of experiments by varying observed and climatological values of snow and SST. This paper discusses the seasonal total rainfall for country as a whole and 850 and 200 hPa wind for the period of 20 years starting from 1985 to 2004. The model has been integrated in the ensemble mode with five different initial conditions from the last week of April and first week of May. The model is able to capture the climatological patterns of seasonal total rainfall and averaged wind at lower and upper levels. Observed snow in the presence of climatological SST as a boundary condition shows much impact on rainfall and circulation than observed SST in the presence of climatological snow. Model performance is good in simulating the normal and excess monsoon conditions; it shows poor skill in capturing deficit monsoon years.     

TESTING FOR REDUNDANCY IN PRODUCT QUALITY CONTROL TEST CRITERIA:AN APPLICATION TO AVIATION TURBINE FUEL

Given a set of test criteria that determine a quality specification,the question often arises whether anyof the tests are redundant because of intercorrelations.Simple selection of tests on the basis of partialcorrelations with the other tests is rejected on the basis that the random error in the data may be causingspurious correlations.One method is to use cross-validation to define the systematic principal components and examine thecorrelation structure in this reduced space.It is shown that the presence of principal componentsdominated by individual tests(‘variable specific’PCs),which are indicated by cross-validation as beingnon-systematic,must be taken into account.Having defined the dimensionality,a variable reductionmethod based on Procrustes rotation selects subsets of tests that preserve the structure of the samples inmultivariate space.This is an attractive proposition in the context of maintaining a quality controlspecification.It is also shown that the variable reduction technique can be used to aid the identificationof the true dimensionality of the data space.This approach is applied to a number of routine tests carriedout on aviation turbine fuel.     

Modeling of groundwater draft based on satellite-derived crop acreage estimation over an arid region of northwest India

Over-exploitation of groundwater for agricultural crops puts stress on the sustainability of natural resources in the arid region of Rajasthan state, India. Hydrogeological study of groundwater levels of the study area during the pre-monsoon (May to June), post-monsoon (October to November) and post-irrigation (February to March) seasons of 2004–2005 to 2011–2012 shows a steady decline of groundwater levels at the rate of 1.28–1.68 m/year, mainly due to excessive groundwater draft for irrigation. Due to the low density of the groundwater observation-well network in the study area, assessment of groundwater draft, and thus groundwater resource management, becomes a difficult task. To overcome the situation, a linear groundwater draft model (LGDM) has been developed based on the empirical relationship between satellite-derived crop acreage and the observed groundwater draft for the year 2003–2004. The model has been validated for a decade, during three year-long intervals (2005–2006, 2008–2009 and 2011–2012) using groundwater draft, estimated through a discharge factor method. Further, the estimated draft was validated through observed pumping data from random sampled villages (2011–2012). The results suggest that the developed LGDM model provides a good alternative to the estimation of groundwater draft based on satellite-based crop area in the absence of groundwater observation wells in arid regions of northwest India.     

Evolution of lower proterozoic epicontinental deposits: Stromatolite-bearing Aravalli rocks of Udaipur,Rajasthan, India

The Aravalli rocks (> 2060 Ma old) which crop out around Udaipur, Western India, comprise a thick sequence of metasediments with stromatolites and basal volcanics resting unconformably over a peneplained basement, known as the Banded Gneissic Complex (ca. 2585 Ma old). The rocks have undergone a very low grade of metamorphism, and display a complex structure resulting from two major and several minor episodes of folding.There are two distinctly different ‘facies sequences’ in the Aravalli rocks, indicating deep-sea and nearshore shelf environments. The stratigraphic sequence of the rocks deposited under the shelf environment starts with basic volcanics and tuffs (altered to greenschists) and quartizites with arkosic conglomerate. In the next sequence carbonates predominate in association with orthoquartzites, carbonaceous phyllites, phyllites, and stromatolitic rock-phosphate. The carbonate sequence passes upward into greywacke-phyllite-lithic arenite in the distal parts and conglomerate-arkose-orthoquartzite in proximal areas. The youngest sequence comprises orthoquartzite with silty arenite.The distribution of different facies, particularly that of dolomite with stromatolitic rock-phosphate, is controlled by sea-floor topography suggesting the presence of an epicontinental sea bounded by a landmass to the west and a series of islands and shoals.Sedimentation in the shelf and epicontinental sea was presumably triggered by development of fault-controlled troughs along craton margins. Terrigenous debris was deposited in newly-developed troughs with contemporaneous volcanicity along trough margins. With the erasing of the ephemeral relief in the provenance, carbonate deposition was initiated. The environment encouraged algal growth and formation of stromatolitic rock phosphate. Carbonaceous phyllites developed in areas of restricted circulation. Rapid influx of terrigenous detritus with renewed tectonism in the next phase resulted in the deposition of a turbidite sequence of greywacke-phyllite and lithic arenite in the deeper parts of the epicontinental sea, and conglomerate-arkose-orthoquartizite in the marginal areas. The final phase of sedimentation was presumably under fluvial conditions which marked the completion of epicontinental trough filling. The nature of the terrigenous clasts indicates a predominantly granitic source of sediments. Supply of sediment was mainly from the continent to the east and partly from a landmass to the west. The cycle of sedimentation noted in the epicontinental Aravalli sea is broadly similar to the model of tectonic stages suggested by Krynine (1942).