Hydrogeochemical processes controlling the high fluoride concentration in groundwater: a case study at the Boden block area,Orissa, India

The present investigation reports the assessment of hydrochemical/geochemical processes controlling the concentration of fluoride in groundwater of a village in India (Boden block, Orissa). Boden block is one of the severely affected fluoride-contaminated areas in the state of Orissa (India). The sampling and subsequent analysis of water samples of the study area was carried out following standard prescribed methods. The results of the analysis indicate that 36.60% groundwater F⁻ concentration exceeds the limit prescribed by the World Health Organization for drinking water. The rock interaction with groundwater containing high concentration of HCO₃⁻ and Na⁺ at a higher pH value of the medium could be one of the important reasons for the release of F⁻ from the aquatic matrix into groundwater. Geochemical classification of groundwater based on Chadha rectangular diagram shows that most of the groundwater samples having fluoride concentration more than 1.5 mg L⁻¹ belongs to the Na-K-HCO₃ type. The saturation index values evaluated for the groundwater of the study area indicated that it is oversaturated with respect to calcite, whereas the same is undersaturated with respect to fluorite content. The deficiency of calcium ion concentration in the groundwater from calcite precipitation favors fluorite dissolution leading to excess of fluoride concentration. The risk index was calculated as a function of fluoride level in drinking water and morbidity of fluorosis categorizes high risk for villages of Amera and Karlakote panchayat of Boden block.     

The impact assessment of Diwali fireworks emissions on the air quality of a tropical urban site, Hyderabad, India, during three consecutive years

Diwali is one of the largest festivals for Hindu religion which falls in the period October–November every year. During the festival days, extensive burning of firecrackers takes place, especially in the evening hours, constituting a significant source of aerosols, black carbon (BC), organics, and trace gases. The widespread use of sparklers was found to be associated with short-term air quality degradation events. The present study focuses on the influence of Diwali fireworks emissions on surface ozone (O₃), nitrogen oxides (NO _x ), and BC aerosol concentration over the tropical urban region of Hyderabad, India during three consecutive years (2009–2011). The trace gases are analyzed for pre-Diwali, Diwali, and post-Diwali days in order to reveal the festivity’s contribution to the ambient air quality over the city. A twofold to threefold increase is observed in O₃, NO _x , and BC concentrations during the festival period compared to control days for 2009–2011, which is mainly attributed to firecrackers burning. The high correlation coefficient (~0.74) between NO _x and SO₂ concentrations and higher SO₂/NO _x (S/N) index suggested air quality degradation due to firecrackers burning. Furthermore, the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation-derived aerosol subtyping map also confirmed the presence of smoke aerosols emitted from firecrackers burning over the region. Nevertheless, the concentration level of pollutants exhibited substantial decline over the region during the years 2010 and 2011 compared to 2009 ascribed to various awareness campaigns and increased cost of firecrackers.     

Study on concentration of ambient NH 3 and interactions with some other ambient trace gases

We present diurnal variation of ambient ammonia (NH₃) in relation with other trace gases (O₃, CO, NO, NO₂, and SO₂) and meteorological parameters at an urban site of Delhi during winter period. For the first time, ambient ammonia (NH₃) was monitored very precisely and continuously using ammonia analyzer, which operates on chemiluminescence method. NH₃ estimation efficiency of the chemiluminescence method (>90%) is much higher than the conventional chemical trapping method (reproducibility 4.5%). Ambient NH₃ concentration reaches its maxima (46.17 ppb) at night and minimum during midday. Result reveals that the ambient ammonia (NH₃) concentration is positively correlated with ambient NO (r ²?=?0.79) and NO₂ (r ²?=?0.91) mixing ratio and negatively correlated with ambient temperature (r ²?=???0.32). Wind direction and wind speed indicates that the nearby (~500 m NW) agricultural fields may be major source of ambient NH₃ at the observational site.     

Assessment of flubendiamide residues in pigeon pea in different agro-climatic zones of India

Supervised field trials were conducted at the research farms of four agricultural universities located at different agro-climatic zones of India to find out the harvest time residues of flubendiamide and its des-iodo metabolite on pigeon pea (Cajanus cajan) during the year 2006-2007. Two spray applications of flubendiamide 20 WDG at 50 g (T(1)) and 100 g (T(2)) a.i./ha were given to the crop at 15-days interval. The foliage samples at different time intervals were drawn at only one location, however, the harvest time samples of pigeon pea grain, shell, and straw were drawn at all the four locations. The residues were estimated by HPLC coupled with UV-VIS variable detector. No residues of flubendiamide and its des-iodo metabolite were found at harvest of the crop at or above the LOQ level of 0.05 μg/g. On the basis of the data generated, a pre-harvest interval (PHI) of 28 days has been recommended and the flubendiamide 20 WDG has been registered for use on pigeon pea by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India and the MRL has been fixed by Ministry of Health and Family Welfare, Government of India under Prevention of Food and Adulteration as 0.05 μg/g on pigeon pea grains.     

Evaluation of groundwater quality in and around Peenya industrial area of Bangalore, South India using GIS techniques

Groundwater resource forms a significant component of the urban water supply. Declining groundwater levels in Bangalore Urban District is generally due to continuous overexploitation during the last two decades or more. There is a tremendous increase in demand in the city for good quality groundwater resource. The present study monitors the groundwater quality using geographic information system (GIS) techniques for a part of Bangalore metropolis. Thematic maps for the study area are prepared by visual interpretation of SOI toposheets on 1:50,000 scale using MapInfo software. Physicochemical analysis data of the groundwater samples collected at predetermined locations form the attribute database for the study, based on which spatial distribution maps of major water quality parameters are prepared using MapInfo GIS software. Water quality index was then calculated by considering the following water quality parameters--pH, total dissolved solids, total hardness, calcium hardness, magnesium hardness, alkalinity, chloride, nitrate and sulphate to find the suitability of water for drinking purpose. The water quality index for these samples ranged from 49 to 502. The high value of water quality index reveals that most of the study area is highly contaminated due to excessive concentration of one or more water quality parameters and that the groundwater needs pretreatment before consumption.     

Chemical characteristics of aerosols and trace gas distribution over North and Central India

A field campaign on aerosol chemical properties and trace gases measurements was carried out along the Delhi-Hyderabad-Delhi road corridor (spanning about 3,200 km) in India, during February 1-29, 2004. Aerosol particles were collected on quartz and cellulose filters using high volume (PM(10)) sampler at various locations along the route (i.e., urban, semi-urban, rural, and forest areas) and have been characterized for major cations (Na(+), Ca(2+), Mg(2+), K(+), and NH (4) (+)), anions (Cl(-), NO (3)(-), and SO (4)(2-)), and heavy metals (Cu, Cd, Fe, Zn, Mn, and Pb). Simultaneously, we measured NO(2) and SO(2) gases. These species show large spatial and temporal variations. The ambient PM(10) concentration has been observed to be the highest (55 ± 4 μg m(-3)) near semi-urban areas followed by forest areas (48 ± 2 μg m(-3)) and in rural areas (44 ± 22 μg m(-3)). The concentrations of NO( x ) (NO(2)+NO) and SO(2) ranged from 16 to 69 μg m(-3) and 4 to 11 μg m(-3), respectively. Among anions, NO(3)(-) and SO(4) (2-) are the major constituents of PM(10). The urban and semi-urban sites showed enhanced concentrations of Fe, Zn, Mn, Cd, and Pb. This study provide information about atmospheric concentrations of various species in the northern to central India, which may be important for policy makers to better understand the air quality of the region.     

Persistence and vertical distribution of termiticide fipronil in modified ground board test

Fipronil termiticide belongs to phenyl-pyrazole class of chemical compounds. It has broad-spectrum activity particularly against house hold pests such as cockroaches, mosquitoes, locusts, ticks, and fleas at both larval and adult stages. At high dosage it can be used to control subterranean termites in building foundations. To evaluate long term efficacy against termites the persistence and vertical distribution of fipronil was studied under natural weather conditions of Dehradun, India. Fipronil was applied at four concentrations i.e. 0.05, 0.1, 0.25 and 0.5% a.i ha⁻¹ by drenching 17 × 17 in.² plot prepared as per modified ground board test. Soil samples were collected after 22, 38 and 56 months of treatment up to the depth of 75 cm. The soil core was cut into five distinct sections i.e. 0–15, 15–30, 30–45, 45–60 and 60–75 cm depth. The residues were extracted by shaking 20 g soil sample with acetone. The acetone extract was concentrated and cleaned-up over florisil column. Fipronil residues were estimated on GLC at 220, 260, and 300°C oven, injector and detector temperature respectively. Fipronil was found to persist beyond 56 months after application. Two metabolites viz. desulfinyl and sulfide-fipronil were detected in sampling after 22 months of application that also dissipated with time. Fipronil residues were found up to 60 cm depth. The residues in deeper layers dissipate slowly with time and after 56 months of treatment residues were detected only up to 30 cm depth.     

Identification and analysis of polyaromatic hydrocarbons (PAHs)—biodegrading bacterial strains from refinery soil of India

Polyaromatic hydrocarbons (PAHs) utilizing bacteria were isolated from soils of seven sites of Mathura refinery, India. Twenty-six bacterial strains with different morphotypes were isolated. These strains were acclimatized to utilize a mixture of four polycyclic aromatic hydrocarbons, i.e., anthracene, fluorene, phenanthrene, and pyrene, each at 50 mg/L concentration as sole carbon source. Out of total isolates, 15 potent isolates were subjected to 16S rDNA sequencing and identified as a member of diverse genera, i.e., Bacillus, Acinetobacter, Stenotrophomonas, Alcaligenes, Lysinibacillus, Brevibacterium, Serratia, and Streptomyces. Consortium of four promising isolates (Acinetobacter, Brevibacterium, Serratia, and Streptomyces) were also investigated for bioremediation of PAH mixture. This consortium was proved to be efficient PAH degrader resulting in 40–70 % degradation of PAH within 7 days. Results of this study indicated that these genera may play an active role in bioremediation of PAHs.     

Seasonal variations and source profile of <Emphasis Type="Italic">n</Emphasis>-alkanes in particulate matter (PM<Subscript>10</Subscript>) at a heavy traffic site,Delhi

Delhi is one of the most polluted cities in the world. The generation of aerosols in the lower atmosphere of the city is mainly due to a large amount of natural dust advection and sizable anthropogenic activities. The compositions of organic compounds in aerosols are highly variable in this region and need to be investigated thoroughly. Twenty-four-hour sampling to assess concentrations of n-alkanes (ng/m³) in PM₁₀ was carried out during January 2015 to June 2015 at Indira Gandhi Delhi Technical University for Women (IGDTUW) Campus, Delhi, India. The total average concentration of n-alkanes, 243.7 ± 5.5 ng/m³, along with the diagnostic tools has been calculated. The values of CPI₁, CPI₂, and CPI₃ for the whole range of n-alkanes series, petrogenic n-alkanes, and biogenic n-alkanes were 1.00, 1.02, and 1.04, respectively, and C _max were at C₂₅ and C₂₇. Diagnostic indices and curves indicated that the dominant inputs of n-alkanes are from petrogenic emissions, with lower contribution from biogenic emissions. Significant seasonal variations were observed in average concentrations of n-alkanes, which is comparatively higher in winter (187.4 ± 4.3 ng/m³) than during the summer season (56.3 ± 1.1 ng/m³).