Bioefficacy,dissipation kinetics and safety evaluation of selected insecticides in Allium cepa L

This paper reports the bioefficacy of selected insecticides against thrips and their pre-harvest intervals (PHI) in onion pertaining to their recommended application rates and maximum residue limits. Profenophos, methomyl and imidacloprid showed comparatively higher bioefficacy against thrips. GC-MS and LC-MS/MS-based residue analysis methods in onion bulbs and composite matrix of bulbs+leaves were thoroughly validated. The residue data for bulb+leaves was assessed with reference to the EU-MRLs applicable for spring onion. Dimethoate was the most stable chemical with PHI of 52.5 days, followed by monocrotophos (24 days) and carbofuran (20.5 days). The PHIs of profenophos, chlorpyrifos, methomyl and cypermethrin were similar and within the range of 10–13 days. Imidacloprid and λ-cyhalothrin had similar PHI of 4.5 days. Spinosad was the fastest-degrading chemical with PHI of 2 days. The combined bioefficacy and residue dynamics information will support label-claim of these insecticides for the management of thrips in onion, help in scheduling their applications in pest management program as per relative PHIs and minimize the residue accumulations at harvest. The dietary exposure was less than the maximum permissible intake for most of the insecticides on all sampling days except for dimethoate and monocrotophos.     

Uptake of Cd, Cu, Ni and Zn by the Water Hyacinth, Eichhornia Crassipes (Mart.) Solms from Pulverised Fuel Ash (PFA) Leachates and Slurries

The main solid waste product from coal-fired power stations is pulverised fuel ash (PFA), which can be enriched in toxic elements. Disposal of PFA by dry (in landfills) or wet (by slurrying) disposal methods can release these elements into the environment. Thereafter, the contaminants can be taken up by biota such as Eichhornia crassipes, a common aquatic plant, which has the ability to accumulate elements from water. This study investigates the uptake of Cd, Cu, Ni and Zn by E. crassipes grown in leachates and slurries prepared from two different PFA samples. PFA samples were obtained from Indraprastha Power Station (IPP Stn.) in New Delhi, India and the Ratcliffe-on-Soar Power Station in the UK. E. crassipes grown in PFA leachates and slurries at 1:5 and 1:50 solid:liquid (PFA:deionised water) ratios show that the plant has a very high accumulation capacity for Cd, Cu, Ni and Zn from both leachates and slurries and the uptake of these metals is stronger in the roots than in the tops of the plant. Metal accumulation, as shown by the accumulation factor (AF) values, is higher from both leachates and slurries for plants grown in the 1:50 (PFA:DIW) ratios than in the 1:5 ratios, initial metal concentrations being higher in the 1:5 ratios than in the 1:50 ratios. Lower metal accumulation in the plants grown in slurries than in leachates is related to the high turbidity of growth medium in slurries resulting in ash particles adhering to the root surfaces thus reducing the surface area of metal absorption. Eichhornia plants are able to reduce the pH of all leachates, especially the highly alkaline Ratcliffe leachates to near neutral conditions. Accumulation of Cd and Zn by the plant is higher from the lower pH IPP leachates than the Ratcliffe leachates, indicating that these metals are more soluble and bioavailable in the acidic medium. However, accumulation of Cu and Ni is independent of the pH of the leachates, indicating that other factors, such as metal species, presence of complexing agents in the growth solutions, and effects of competing metal ions may be contributory factors towards the metal uptake and accumulation by the plant.     

Remotely-Sensed Active Fire Data for Protected Area Management: Eight-Year Patterns in the Manas National Park, India

The Terai-Duar savanna and grasslands, which once extended along most of the Himalayan foothills, now only remain in a number of protected areas. Within these localities, grassland burning is a major issue, but data on frequency and distribution of fires are limited. Here, we analysed the incidence of active fires, which only occur during the dry season (Nov.–Mar.), within a significant area of Terai grasslands: the Manas National Park (MNP), India. We obtained locations of 781 fires during the 2000–2008 dry seasons, from the Fire Information for Resource Management System (FIRMS) that delivers global MODIS hotspot/fire locations using remote sensing and GIS technologies. Annual number of fires rose significantly from around 20 at the start of the study period to over 90 after 2002, with most (85%) detected between December and January. Over half of the fires occurred in tall grasslands, but fire density was highest in wetland and riverine vegetation, dry at the time. Most burning took place near rivers, roads and the park boundary, suggesting anthropogenic origins. A kernel density map of all recorded fires indicated three heavily burnt areas in the MNP, all within the tall grasslands. Our study demonstrates, despite some technical caveats linked to fire detection technology, which is improving, that remote fire data can be a practical tool in understanding fire concentration and burning temporal patterns in highly vulnerable habitats, useful in guiding management.     

Persistence and risk assessment of spiromesifen on tomato in India: a multilocational study

Supervised field trials were conducted at four different agro-climatic locations of India to evaluate the dissipation pattern and risk assessment of spiromesifen on tomato. Spiromesifen 240 SC was sprayed on tomato at 150 and 300 g a.i.?ha^?1. Samples of tomato fruits were drawn at 0, 1, 3, 5, 7, 10 and 15 days after treatment and soil at 15 days after treatment. Quantification of residues was done on gas chromatograph–mass spectrophotometer in selective ion monitoring mode in the mass range of 271–274 (m/z). The limit of quantification of the method was found to be 0.05 mg kg^?1, while the limit of determination was 0.015 mg kg^?1. Residues were found below the LOQ of 0.05 mg kg^?1 in 10 days at both the doses of application at all the locations. Spiromesifen dissipated with a half-life of 0.93–1.38 days at the recommended rate of application and 1.04–1.34 days at the double the rate of application. Residues of spiromesifen in soil were detectable level (<0.05 mg kg^?1) after 15 days of treatment. A preharvest interval (PHI) of 1 day has been recommended on tomato on the basis of data generated under All India Network Project on Pesticide Residues. Spiromesifen 240 SC has been registered for its use on tomato by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of spiromesifen on tomato has been fixed by Food Safety Standard Authority of India, Ministry of Health and Family Welfare, Government of India as 0.3 μg/g after its risk assessment.     

Hydrochemical analysis to evaluate the seawater ingress in a small coral island of India

The sustainable development of the limited groundwater resources in the tropical island requires a thorough understanding of detail hydrogeological regime including the hydrochemical behavior of groundwater. Detail analysis of chemical data of groundwater helps in assessing the different groundwater zone affected by formation as well as sea water. Groundwater and saline water interaction is better understood using groundwater major ion chemistry over an island aquifer. Multivariate methods to analyze the geochemical data are used to understand geochemical evolution of groundwater. The methods are successfully used to group the data to evaluate influence of various environs in the study area. Various classification methods such as piper, correlation method, and salinity hazard measurements are also employed to critical study of geochemical characteristics of groundwater to identify vulnerable parts of the aquifer. These approaches have been used to successfully evaluate the aquifer zones of a tiny island off the west coast of India. The most part of island is found to be safe for drinking, however some parts of island are identified that are affected by sea water ingress and dissolution of formation minerals. The analysis has successfully leaded to identification of that part of aquifer on the island which needs immediate attention for restoration and avoids further deterioration.     

Heavy metal assessment using geochemical and statistical tools in the surface sediments of Vembanad Lake, Southwest Coast of India

The geochemical distribution and enrichment of ten heavy metals in the surface sediments of Vembanad Lake, southwest coast of India was evaluated. Sediment samples from 47 stations in the Lake were collected during dry and wet seasons in 2008 and examined for heavy metal content (Al, Fe, Mn, Cr, Zn, Ni, Pb, Cu, Co, Cd), organic carbon, and sediment texture. Statistically significant spatial variation was observed among all sediment variables, but negligible significant seasonal variation was observed. Correlation analysis showed that the metal content of sediments was mainly regulated by organic carbon, Fe oxy-hydroxides, and grain size. Principal component analysis was used to reduce the 14 sediment variables into three factors that reveal distinct origins or accumulation mechanisms controlling the chemical composition in the study area. Pollution intensity of the Vembanad Lake was measured using the enrichment factor and the pollution load index. Severe and moderately severe enrichment of Cd and Zn in the north estuary with minor enrichment of Pb and Cr were observed, which reflects the intensity of the anthropogenic inputs related to industrial discharge into this system. The results of pollution load index reveal that the sediment was heavily polluted in northern arm and moderately polluted in the extreme end and port region of the southern arm of the lake. A comparison with sediment quality guideline quotient was also made, indicating that there may be some ecotoxicological risk to benthic organisms in these sediments.     

Heavy metal uptake and its effect on macronutrients, chlorophyll, protein, and peroxidase activity of Paspalum distichum grown on sludge-dosed soils

This study assessed the heavy metal (Cr, Mn, Ni, Cu, Zn, and Pb) uptake and its effect on biochemical parameters in Paspalum distichum, a wetland plant. Sludge collected from Bhalswa waste dump, New Delhi, was used as heavy metal source and dosed in different proportions viz. 20%, 40%, 60%, and 80% to the garden soil. The plants accumulated metals mostly in belowground organs. The metal accumulation followed the order: Cr>Mn>Cu>Zn>Ni>Pb. The range of heavy metal concentration in tissue of belowground organs after 180 days of growth was 1,778.65–4,288.01 ppm Cr, 828.11–1,360 ppm Mn, 236.52–330.07 ppm Ni, 155.79–282.35 ppm Cu, 27.05–91.16 ppm Zn, and 27.09–50.87 ppm Pb. The biochemical parameters viz. chlorophyll and protein contents and peroxidase (POD) activity exhibited no considerable adverse effect indicating the plants’ tolerance towards heavy metals. The high POD activity and synthesis of new protein bands at high sludge-dosed plants were also in support of this fact.     

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.     

Association between road traffic noise and prevalence of coronary heart disease

There is an established evidence that exposure to high levels of road traffic noise is associated with elevated risk of coronary heart disease (CHD). The results however have been heterogeneous and mostly inconclusive. The present investigation aimed to examine this association in adult subjects, with a secondary aim of identifying potentially vulnerable sub-populations. Similar studies have never been reported from Indian population. For exposure assessment, the time-weighted road traffic noise indicator, L _den, was used as a continuous and categorical predictor. A cross-sectional study was designed, and sociodemographic and lifestyle- and health-related characteristics were recorded for 909 (533 females and 376 males) subjects aged 18–80 years. The respondents living in areas with L _den?<?60 dB(A) were designated as the reference group. Odds for self-reported CHD in relation to traffic noise exposure were estimated by univariate and multifactorial logistic regression with adjustments for potential confounders and effect modifiers. The adjusted odds ratio (OR) for self-reported CHD was 1.72 (95 % CI 1.36–2.19) per 5 dB(A) increase of L _den (range 55–80 dB(A)). A gender-related risk difference was observed among male (OR 1.47 (1.07–2.02)) and female (OR 1.83 (1.27–2.65)) respondents. A stronger effect for subjects in the age group 55–64 years old was found, with age, residence period, body mass index, and self-reported stress being significant confounders. This study suggests epidemiological evidence that exposure to road traffic noise of L _den?>?65 dB(A) may be associated with occurrence of CHD in adult subjects. A trend was observed indicating increasing risk with higher exposure levels. The study results are also suggestive of higher risk of outcome among those with other chronic ailments (diabetes, pulmonary, or renal issues) and residing in the same location in excess of 15 years. Orientation of bedroom windows was identified as a significant effect modifier.