Semi-arid Region Of India Research Articles

Zinc, boron and sulphur deficiencies are holding back the potential of rainfed crops in semi-arid India: Experiences from participatory watershed management

Little attention has been paid to the diagnosis of deficiencies of micronutrients such as zinc (Zn) and boron (B) and secondary nutrient such as sulphur (S) in rainfed systems. We evaluated Zn, B and S status of 1617 farmers’ fields in 14 districts of the semi-arid tropical India. Results showed that most of the soil samples were low to medium in organic carbon contents. Results also revealed that Zn deficiency ranged from 2 to 100%, B deficiency ranged form 0 to 100%, and S deficiency ranged from 40 to 100% in farmers’ fields across the districts. On-farm trials were conducted to study the response of rainfed crops to Zn, B and S application, and the residual effects of B and S, genotypic variations in chickpea cultivars in response to these nutrients and the economics of Zn, B and S use. Results from on-farm trials conducted during 2002-2006 showed significant yield responses of finger millet, maize, sunflower, soybean, groundnut and chickpea to application of Zn, B and S. There was significant residual effect of B and S applied to rainy season soybean on post-rainy season chickpea. Among genotypes of chickpea, KAK-2 was more responsive than other cultivars. Application of Zn, B and S also significantly increased the uptake of Zn, B and S in the crop biomass. Results also showed that application of Zn, B and S along with N+P was economical and critical for higher and sustained productivity of rainfed crops in semi-arid regions of India.

Gender Mainstreaming in Climate Change Response: A Perspective for Inclusive Response

This paper is an attempt to draw the linkages between gender and climate change from adaptive perspectives to address the phenomenon. It brings in the impacts and a strategic action to challenge and implement measures based on studies carried out in the semi-arid regions of India, where distress and devastating conditions of livelihood options are the only alternatives for women in the rural communities.

Chemometric analysis to infer hydro-geochemical processes in a semi-arid region of India

Groundwater exploitation in Punjab has increased in last few decades due to rapid increase in industrialization, population, crop production, and erratic monsoon. In the present study, groundwater samples from 29 locations were collected and analyzed for almost all major anions, cations, and heavy metals. The analyzed parameters formed the attribute database for statistical analysis. The study approach included multivariate statistical analysis of hydro-chemical data to identify hydro-geochemical processes occurring in the study area and its relation to groundwater quality. The principal component analysis produced seven significant factors that explained nearly 77 % of the cumulative variance. Factor 1 explained nearly 22.05 % of dataset with variables loading indicating mineralization of geological component of soil. Trilinear plot and other graphical methods were also used to identify chemical facies of groundwater and geochemical processes occurring in study area. The water type in the study area is of Na/K–Mg–HCO3 type. It was found that the general hydro-geochemistry of groundwater in the study area dominated is by the processes such as carbonate/silicate weathering, ion-exchange, and dissolution. Thus, statistical methods can prove to be an effective tool understanding hydro-geochemistry of a region along with conventional graphical methods.

Alleviation of Multinutrient Deficiency for Productivity Enhancement of Rain-Fed Soybean and Finger Millet in the Semi-arid Region of India

Soil nutrient contents were determined in 802 surface soil samples (0–15 cm deep) collected from farmers' fields that support extensive cultivation of soybean (Glycine max L.) and finger millet (Eleusine coracana G.), spread across three districts, in the semi-arid regions of Karnataka, India. Following soil analysis, on-farm crop trials were conducted during 2005–2007 to study the crop response to the soil application of nitrogen (N), phosphorus (P), sulfur (S), boron (B), and zinc (Zn) fertilizers. Analyses of soil samples revealed that 4–83% fields were deficient in N, 34–65% in P, 83–93% in extractable S, 53–96% in B, and 34–88% of farmers' fields were deficient in Zn. On-farm trials conducted during the three rainy seasons (2005, 2006, and 2007) significantly (P ≤ 0.05) enhanced crop productivity indices such as yields of grain, stover, and total biomass in soybean and finger millet crops. Integrated management of deficient nutrients in finger millet and soybean crops significantly enhanced the grain and straw uptake of N, P, K, S, and Zn.

Seasonal Variation and Sources of Polycyclic Aromatic Hydrocarbons (PAHs) in Indoor and Outdoor Air in a Semi Arid Tract of Northern India

PAHs concentration in particulate and gas phase was investigated in indoor and outdoor air of urban residential and roadside homes in a semiarid region of India. Samples were collected during winter and summer season (Nov 2006–Jun 2007). In particulate phase at roadside homes the annual mean concentration of PAHs in indoor was 5.53 to 952.28 ng/m 3

Analysis of molecular genetic diversity in a representative collection of foxtail millet [Setaria italica (L.) P. Beauv.] from different agro-ecological regions of India

Foxtail millet [Setaria italica (L.) P. Beauv.], an important crop of East Asia is known for its drought tolerance and was once an indispensible crop of vast rainfed areas in semi-arid regions in India. In India it is cultivated in Andhra Pradesh, Karnataka, Maharashtra, Tamil Nadu, Rajasthan, Madhya Pradesh, Uttar Pradesh and north eastern states. The grain finds use in several local recipes such as roti (bread), jaula, singal, sirol. Foxtail millet grain contains 12.3% protein, 4.7% fat, 60.6% carbohydrates, and 3.2% ash. The present study was conducted to analyse the genetic diversity among foxtail accessions from different states of India and a few exotic accessions using RAPD and ISSR techniques and identify diverse accessions for use in variety improvement programmes. A set of 125 foxtail millet accessions selected from 11 different agro-ecological regions of India were analyzed using random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) marker techniques. A total of 146 (115 RAPD and 31 ISSR) scoreable markers were generated with 16 RAPD and four ISSR primers. The dendrogram generated using Nei's genetic distances and principal component analyses revealed presence of two clusters and two subclusters in group I. The accessions from Andhra Pradesh, Karnataka, Maharashtra and Uttarakhand were more diverse since they were distributed in both the clusters. There was no clear geographical differentiation observable. The bootstrap support for the major groups identified was strong (above 80%) indicating good statistical support. The average value of Nei and Li's genetic distance was lowest (0.081) for accessions from West Bengal while the collections from Karnataka showed highest dissimilarity (average genetic distance = 0.239). The average genetic distance for all 125 accessions together was 0.177 indicating presence of only moderate genetic diversity in the collections. The analysis of molecular variance indicated that only 2.76% variation was explained by variations among the groups and 11.55% among populations within groups. However the percentage of variation observed within populations was high (85.68). The value of Fst was observed to be very low (0.028) indicating low differentiation of the accessions analysed. The population genetic analysis carried out indicates that highest number of alleles per locus (1.745 ± 0.438) was observed for Andhra Pradesh with 35 accessions. When four eco-geographic regions were considered, the southern region comprising AP, Karnataka and TN showed the highest number of alleles per locus (1.787 ± 0.411). The value of Gst was lowest for south (0.123) and highest for central west (0.455). This indicated that all the landraces from south share common alleles. The gene flow between the accessions from different regions was also observed to be high with the highest migration (3.557) recorded for south.

Occurrence of Arbuscular Mycorrhizal Fungi in Rhizosphere of Jatropha curcas L. in Arid and Semi Arid Regions of India

A study was conducted to identify common arbuscular mycorrhizal (AM) fungi present in rhizosphere of Jatropha curcas L., an important bio-diesel crop, from different arid and semi arid regions of India viz., Jodhpur (Rajasthan), Hissar (Haryana), Jhansi and Lalitpur (Uttar Pradesh) and Hyderabad (Andhra Pradesh). A total of 20 AM species were recorded, which consisted of two species of Acaulospora and 18 species of Glomus. The highest frequency of occurrence was recorded for Glomus intraradix (100%), followed by Acaulospora scrobiculata (83%), G. etunicatum (50%) and Glomus 1 (50%). Maximum species richness was recorded at Jodhpur, followed by Jhansi, Hissar, Hyderabad and Lalitpur. The results seem to suggest that species richness was more in arid regions as compared to semi arid areas.

Nonparametric Statistical Downscaling of Temperature, Precipitation, and Evaporation in a Semiarid Region in India

The climate impact studies in hydrology often rely on climate change information at fine spatial resolution. Because general circulation models (GCMs) operate on a coarse scale, the output from a GCM has to be downscaled to obtain the information relevant to hydrologic studies. In this paper, downscaling models are developed using the state-of-the-art nonparametric method K-Nearest Neighbor (K-NN) approach, with an emphasis on optimal choice in selection of nearest neighbors for obtaining simultaneous projections of mean monthly maximum and minimum temperatures (Tmax⁡ and Tmin⁡) as well as monthly precipitation and pan evaporation to lake-basin scale in a semiarid region that is considered to be a climatically sensitive region in India. The performance of the K-NN approach was evaluated based on several statistical performance indicators. A comparison of K-NN has been made with a linear multiple regression (LMR)-based downscaling model. Also, the prevailing view in the literature regarding optimal choice of selection of nearest neighbors is checked with different perturbations. A simple multiplicative shift was used for correcting predictand values. The K-NN-based models are found to be superior to LMR-based models, and, subsequently, the K-NN-based model is applied to obtain future climate projections of the predictands. An increasing trend is observed for Tmax⁡ and Tmin⁡ for A1B, A2, and B1 scenarios, and the precipitation is projected to increase in the future for A2 and A1B scenarios, whereas no trend has been observed for pan evaporation in future.

Uncertainties in downscaled relative humidity for a semi-arid region in India

Monthly scenarios of relative humidity (RH) were obtained for the Malaprabha river basin in India using a statistical downscaling technique. Large-scale atmospheric variables (air temperature and specific humidity at 925 mb, surface air temperature and latent heat flux) were chosen as predictors. The predictor variables are extracted from the (1) National Centers for Environmental Prediction reanalysis dataset for the period 1978–2000, and (2) simulations of the third generation Canadian Coupled Global Climate Model for the period 1978–2100. The objective of this study was to investigate the uncertainties in regional scenarios developed for RH due to the choice of emission scenarios (A1B, A2, B1 and COMMIT) and the predictors selected. Multi-linear regression with stepwise screening is the downscaling technique used in this study. To study the uncertainty in the regional scenarios of RH, due to the selected predictors, eight sets of predictors were chosen and a downscaling model was developed for each set. Performance of the downscaling models in the baseline period (1978–2000) was studied using three measures (1) Nash– Sutcliffe error estimate (Ef), (2) mean absolute error (MAE), and (3) product moment correlation (P ). Results show that the performances vary between 0.59 and 0.68, 0.42 and 0.50 and 0.77 and 0.82 for Ef, MAE and P. Cumulative distribution functions were prepared from the regional scenarios of RH developed for combinations of predictors and emission scenarios. Results show a variation of 1 to 6% RH in the scenarios developed for combination of predictor sets for baseline period. For a future period (2001–2100), a variation of 6 to 15% RH was observed for the combination of emission scenarios and predictors. The variation was highest for A2 scenario and least for COMMIT and B1 scenario.

Assessing Soil Quality in a Semiarid Tropical Watershed Using a Geographic Information System

Subsistence agriculture under rainfed conditions and declining or stagnant yields on irrigated farmland has raised concerns about resource management and long-term sustainability in the subtropical, semiarid region of India. Soil quality assessment has been recognized as an important step toward understanding the effects of land management practices within an agricultural watershed. This study addressed the spatial variability of soil properties and their quality at the watershed level using geostatistical methods. Soil samples from the 0- to 20-cm depth were collected from 118 locations on a 100- by 100-m grid across an 88-ha watershed at Sakaliseripalli village in the Nalgonda District in Andhra Pradesh State, India. Geostatistical analysis showed that most of the soil parameters were moderately spatially dependent. An assessment framework, including a minimum data set, linear scoring technique, and additive indices, was used to evaluate the soil quality index (SQI). Principal component analysis identified cation exchange capacity, exchangeable Na percentage, DTPA-extractable Zn, available P, available water, and dehydrogenase activity as the most important indicators for evaluating soil quality. A kriged map of SQI was prepared for the watershed. The SQI was higher in irrigated systems (3.01) than under rainfed conditions (2.53), and it was 2.61 and 2.53 in fallow and permanent fallow fields, respectively. In this study, potential soil loss calculated using the Universal Soil Loss Equation and crop yield were identified as the quantifiable management goals; the results indicated that good soils having higher soil quality indices were also productive and less erosion prone.

Anthropogenic aerosol fraction over Afro-Asian regions inferred using Kalpana-I and MISR data

Mineral dust constitutes the single largest contributor of natural aerosols over continents. The first step towards separating natural aerosol radiative impact from its anthropogenic counterparts over continents is to gather information on dust aerosols. The infrared (IR) radiance (10.5–12.5 μm) acquired from the Kalpana-I satellite (∼8-km resolution) was used to retrieve regional characteristics of dust aerosols over the Afro-Asian region during the winter of 2004, coinciding with a national aerosol campaign. Here, we used aerosol-induced IR radiance depression as an index of dust load. The regional distribution of dust over various arid and semi-arid regions of India and adjacent continents has been estimated, and these data in conjunction with regional maps of column aerosol optical depth (AOD) are used to infer anthropogenic aerosol fraction. Surprisingly, even over desert locations in India and Saudi Arabia, the anthropogenic fraction was relatively high (∼0.3 to 0.4) and the regionally averaged anthropogenic fraction over India was 0.62 ± 0.06.

Microsatellite Analysis of Genetic Population Structure of Zebu Cattle (Bos indicus) Breeds from North-Western Region of India

The present study aims to understand the existing genetic diversity and structure of six native cattle breeds (Rathi, Tharparkar, Nagori, Mewati, Gir, and Kankrej) adapted to the north-western arid and semi-arid region of India based on microsatellite loci. Various diversity estimates, mean number of alleles (12.84); effective number of alleles (5.02); gene diversity (0.769), and observed heterozygosity (0.667) reflected the existence of substantial within-breed diversity in all the investigated cattle breeds. Mean estimates of F-statistics: FIT = 0.144 ± 0.023, FIS = 0.071 ± 0.021, and FST = 0.078 ± 0.014 were significantly different from zero (P < 0.05). The interbreed relationships indicated moderate level of breed differentiation between the six cattle breeds with least differentiation between Kankrej-Mewati pair. The phylogeny structuring further supported close grouping of Kankrej and Mewati breeds. Correspondence analysis plotted Rathi, Tharparkar, and Gir individuals into three separate areas of multivariate space; whereas, Kankrej, Mewati, and Nagori cattle showed low breed specific clustering. This reflected the existence of discrete genetic structure for Tharparkar, Rathi, and Gir, the prominent dairy breeds of the region; whereas, admixture was observed for Kankrej, Mewati, and Nagori individuals.

Assessment of Groundwater Potential in a Semi-Arid Region of India Using Remote Sensing, GIS and MCDM Techniques

Remote sensing (RS) and geographic information system (GIS) are promising tools for efficient planning and management of vital groundwater resources, especially in data-scarce developing nations. In this study, a standard methodology is proposed to delineate groundwater potential zones using integrated RS, GIS and multi-criteria decision making (MCDM) techniques. The developed methodology is demonstrated by a case study in Udaipur district of Rajasthan, western India. Initially, ten thematic layers, viz., topographic elevation, land slope, geomorphology, geology, soil, pre- and post-monsoon groundwater depths, annual net recharge, annual rainfall, and proximity to surface water bodies were considered in this study. These thematic layers were scrutinized by principal component analysis technique to select influential layers for groundwater prospecting. Selected seven thematic layers and their features were assigned suitable weights on the Saaty’s scale according to their relative importance in groundwater occurrence. The assigned weights of the thematic layers and their features were then normalized by using AHP (analytic hierarchy process) MCDM technique and eigenvector method. Finally, the selected thematic maps were integrated by weighted linear combination method in a GIS environment to generate a groundwater potential map. Thus, four groundwater potential zones were identified and demarcated in the study area, viz., ‘good’, ‘moderate’, ‘poor’ and ‘very poor’ based on groundwater potential index values. The area falling in the ‘good’ zone is about 2,113 km2 (17% of the total study area), which encompasses major portions of Sarada, Salumber, Girwa, Dhariawad, and Mavli blocks of the study area. The northeast and southwest portions along with some scattered patches fall in the ‘moderate’ zone, which encompasses an area of 3,710 km2 (about 29%). The ‘poor’ zone is dominant in the study area which covers an area of 4,599 km2 (36% of the total area). The western portion and parts of eastern and southeast portions of the study area are characterized as having ‘very poor’ groundwater potential, and this zone covers an area of 2,273 km2 (18%). Moreover, in the ‘good’ zone, the mean annually exploitable groundwater reserve is estimated at 0.026 million cubic metres per km2 (MCM/km2), whereas it is 0.024 MCM/km2 in the ‘moderate’ zone, 0.018 MCM/km2 in the ‘poor’ zone, and 0.013 MCM/km2 in the ‘very poor’ zone. The groundwater potential map was finally verified using the well yield data of 39 pumping wells, and the result was found satisfactory.

Application of Watershed-Based Tank System Model for Rainwater Harvesting and Irrigation in India

The SOFTANK model optimally designs the watershed-based tank system by simulating field, tank, and groundwater balances. We applied this model to a small watershed consisting of six tanks (small reservoirs) in the semiarid region of India. We evaluated the existing tank system in this watershed and compared it to a one-tank system. Results showed that one tank at the outlet of the watershed would have been more beneficial [with benefit-cost (BC) ratio of 1.80] than the existing six-tank system (with BC ratio of 1.71). Finally, we performed the analysis for obtaining the optimal tank system for the watershed, and we found that the tanks for irrigation purposes are not economical for the small watershed. The groundwater source was enough for irrigation, so any additional investment in the tanks would be uneconomical. The results demonstrate the importance of the watershed-based tank system approach to design.

Integrated Agriculture Production Systems for Meeting Household Food, Fodder and Fuel Security

Agriculture including crop production and animal husbandry provides for the food, fodder, and fuel needs in rural regions of many countries such as India. Using the knowledge pertinent to complex mixed cropping-livestock systems at the village level, the goal of this study is to develop a rational method for crop selection, such that the capacity for production of food, fodder and biomass fuel can be examined under various cropping patterns. An agricultural survey is carried out in November 2007 for three villages located in the dryland agro-ecozone of Karnataka State, India. Various demands, including human food energy and protein requirements, and constraints, including land area, are modeled for optimal cropping pattern. A clear recommendation of the study is that a substantial shift in village-wide area planted to cereal crops, in all cases over 50%, is necessary to satisfy human and livestock demands. Additionally, there are visible and growing population pressures on the resources in the dryland, semi-arid regions of India, and these strategies will need to be supplemented by improved agronomic practices directed toward increased productivity.

Small holder’s carbon forestry project in Haryana India: issues and challenges

The small scale forestry carbon project in Haryana, India has been registered as a Clean Development Project (CDM) activity and is the first such projects from India. Developed under the Kyoto Protocol of United Nations Framework Convention on Climate Change (UNFCCC), the projects aims at restoring heavily degraded sandune affected private lands and contribute to climate change mitigation. The project is expected to sequester 234,584 tons of carbon dioxide (tCO 2 ) in 20 years project cycle with an average annual sequestration of 11,729 (tCO 2 ) per year. The project is expected to have a total carbon stock of 385,253.1 ton Carbon (tC) in the project life span of 20 years as against 7,920.6 (tC) in the baseline scenario. The carbon credits earned from the project is supposed to provide additional incentives to the smallholders who have formed a cooperative society for this purpose. This paper addresses the issues and challenges in developing the project activity and also discusses the lessons learned in the process. The project is supposed to help in poverty alleviation and has become a success story for rehabilitating degraded lands in semi arid regions of India through plantation forestry.

Decision support for on-farm water management and long-term agricultural sustainability in a semi-arid region of India

Summary The long-term success of irrigated agriculture for sustainable crop production in India depends largely on the careful management of land and water resources. Currently, some serious environmental problems of waterlogging and soil salinization are burgeoning in parts of Haryana State of India; half a million hectare area of the State is already waterlogged. Poor irrigation and drainage management and inadequate exploitation of saline ground water are the main factors responsible for this phenomenon. In order to prevent further degradation and to maintain the food production for the growing population, judicious use of natural resources is a must. A wide range of solutions could be considered to address the problems. But the effectiveness of all the solutions and their combinations cannot be verified with on-farm experiments. Simulation models by way of their predictive capability are often the only viable means of providing input to management decisions. These models can help to forecast the likely impacts of a particular alternative management strategy. In the present study a physical based one-dimensional simulation model SWASALT was employed to evaluate on-farm irrigation water management options. After successful calibration and validation with field experimentation data, several scenario building exercises have been conducted under different crop, soil and rainfall conditions. The water and salt balance component obtained for each simulation run were used to derive water management response indicators. The simulation study revealed that in most conditions, saline water of up to 7.5 dS/m can be used safely on long term basis for crop production. The simulation study further revealed that alternative use of canal and saline water had an edge over mix use. Several alternatives have been suggested for sustainable agricultural production in the region. The strategies suggested, if followed, would lend sustainability to the agricultural production besides substantial increase in production and water resources conservation, by impeding the environmental hazard of waterlogging and soil salinization.

Single primer amplification reaction (SPAR) reveals intra-specific natural variation in Prosopis cineraria (L.) Druce

Prosopis cineraria, an important multipurpose tree and vital component of the otherwise fragile ecosystem of arid and semiarid regions of India. It is highly drought tolerant and sprouts profusely during the extreme dry summer months when most other trees are leafless. P. cineraria is known to exhibit comparable genetic variations at intra-specific and inter-population levels reflected through morphological and cytogenetical diversity in regions, where this plant grows naturally. In the present study, single primer amplification reaction (SPAR) methods have been used for determination of diversity at DNA level in 30 accessions of P. cineraria collected from different districts of Rajasthan. The analyses include the use of six minisatellite core sequence primers for direct amplification of minisatellite DNA (DAMD), eight inter simple sequence repeats (ISSR) and 20 arbitrary primed decamer sequences for random amplification (RAPD) reactions. Upon analysis of the data generated, all the three SPAR methods, either independently and/or in combination, revealed wide range of genetic variation among accessions. Comparison of matrix of individual SPAR method using MxComp component of NTSYS-pc 2.02 K software proving that analysis of natural genetic variation using combination of SPAR methods particularly ISSR and DAMD, rather than an isolated approach, is very effective. Such an approach also yields better information and reflection of the relatedness and affinities at intra-species and inter-population levels. Therefore, it is opined that in order to reveal the intrinsic intra-specific variation, SPAR approaches involving more than one DNA marker may reveal more authentic genetic variation in tropical tree species like P. cineraria.

Phytochemical and physiological changes in Ashwagandha (Withania somnifera Dunal) under soil moisture stress

Ashwagandha, commonly known as the Indian Ginseng (Withania somnifera) is an ingredient in many herbal preparations used for healing various ailments. It is cultivated in semi-arid regions of India as rain-fed crop. The response of this crop (cv. JA-134) to progressive soil moisture deficit on growth, physiology and content of phytochemicals was studied. At the end of treatment period, soil water potential (Ψw) decreased to -10.93, -1.15 MPa at 30 cm depth, predawn leaf water potentials were reduced to -0.62 and -0.51 MPa in the severe and moderate stress. Leaf area was reduced by 27.4% and 34.4% in moderate and severe water stress treatment compared to control. Chlorophyll content was reduced by 60% in the severe water stress. Changes in the steroidal alkaloids and lactones that are the major medicinal active principles derived from root extracts of this plant species was also analyzed. A reduction of 52.6% in net photosynthesis was noticed under severe stress. At the end of the treatment period, moderate and severe stress treatments had 0.751 and 0.714 mg g-1 12-deoxywithastramonolide (12-DWS) content in the roots respectively. The content of 12-DWS and withanolide were at 77% and 93% of the control in the moderate and severe stress, respectively, while yield of these compounds were at 65% and 78% of control in mild and severe stress. Thus, preferential partitioning of biomass in roots leads to higher root yield in moderate stress. Higher root yield partially offset the loss of bioactive compounds under soil moisture stress.

Chemical characterization of water-soluble aerosols in different residential environments of semi aridregion of India

This paper deals with the atmospheric concentrations of PM5 and PM2.5 particulate matter and its water soluble constituents along with the size distribution of ions and spatial variation at three different residential environments in a semiarid region in India. Samples were collected from the indoors and outdoors of urban, rural and roadside sites of Agra during October 2007–March 2008. The mean concentrations of PM2.5 indoors and outdoors were 178 µgm−3 and 195 µgm−3 while the mean concentrations of PM5 indoors and outdoors were 231.8 µgm−3 and 265.2 µgm−3 respectively. Out of the total aerosol mass, water soluble constituents contributed an average of 80% (33% anions, 50% cations) in PM5 and 70% (29% anions, 43% cations) in PM2.5. The indoor–outdoor ratio of water soluble components suggested additional aerosol indoor sources at rural and roadside sites. Indoor–outdoor correlations were also determined which show poor relationships among concentrations of aerosol ions at all three sites. Univariate Pearson correlation coefficients among water soluble aerosols were determined to evaluate the relationship between aerosol ions in indoor and outdoor air.