Residual behavior and risk assessment of flubendiamide on tomato at different agro-climatic conditions in India

Supervised field trials were conducted at four different agro-climatic zones in India to evaluate the dissipation pattern and risk assessment of flubendiamide on tomato. Flubendiamide 480 SC was sprayed on tomato at 48 and 96 g active ingredient (a.i.) ha^?1. Samples of tomato fruits were drawn at 0, 1, 3, 5, 7, 10, 15, and 20 days after treatment. Quantification of residues was done on a high-performance liquid chromatography (HPLC) device with a photo diode array detector. The limit of quantification (LOQ) of this method was found to be 0.01 mg kg^?1 while limit of detection (LOD) being 0.003 mg kg^?1. Residues of flubendiamide were found below the determination limit of 0.01 mg kg^?1 in 20 days at both the dosages in all the locations. The half-life of flubendiamide at an application rate of 48 g a.i.?ha^?1 varied from 0.33 to 3.28 days and at 48-g a.i. ranged from 1.21 to 3.00 days. On the basis of data generated under the All India Network Project on Pesticide Residues, a preharvest interval (PHI) of 1 day has been recommended, and the flubendiamide 480 SC has been registered for its use on tomato by the Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India. The maximum residue limit (MRL) of flubendiamide on tomato has been fixed by the Ministry of Health and Family Welfare, Government of India under Food Safety Standard Authority of India, as 0.07 μg g^?1 after its risk assessment.     

Genotoxicity of titanium dioxide (TiO2) nanoparticles at two trophic levels: plant and human lymphocytes

The environmental fate and behaviour of titanium dioxide (TiO(2)) nanoparticles is a rapidly expanding area of research. There is a paucity of information regarding toxic effect of TiO(2) nanoparticles in plants and to certain extent in humans. The present study focuses on the effect of exposure of TiO(2) nanoparticles in two trophic levels, plant and human lymphocytes. The genotoxicity of TiO(2) nanoparticles was evaluated using classical genotoxic endpoints, comet assay and DNA laddering technique. DNA damaging potential of TiO(2) nanoparticles in Allium cepa and Nicotiana tabacum as representative of plant system could be confirmed in the comet assay and DNA laddering experiments. In Allium micronuclei and chromosomal aberrations correlated with the reduction in root growth. We detected increased level of malondialdehyde (MDA) concentration at 4mM (0.9 μM) treatment dose of TiO(2) nanoparticles in Allium cepa. This indicated that lipid peroxidation could be involved as one of the mechanism leading to DNA damage. A comparative study of the cytotoxic and genotoxic potential of TiO(2) nanoparticles and bulk TiO(2) particles in human lymphocytes also reveal interesting results. While TiO(2) nanoparticles were found to be genotoxic at a low dose of 0.25 mM followed by a decrease in extent of DNA damage at higher concentrations; bulk TiO(2) particles reveal a more or less dose dependent effect, genotoxic only at dose 1.25 mM and above. The study thus confirms the genotoxic potential of TiO(2) nanoparticles in both plant and human lymphocytes.     

Examining Environmental Kuznets Curve for river effluents in India

This study aims to determine the trade-off between river pollution and the growth of the economy in the context of India using the concept of Environmental Kuznets Curve (EKC). According to EKC theory, environmental pressure tends to rise faster than income growth in the early stages of economic development and then declines in the later stages with further economic growth. The present study has used the cross-sectional time series data for river pollutants of Biochemical Oxygen Demand (BOD) and Dissolved Hydrogen Ions (PH) across various states of India for the period 1990–1991 to 2005–2006. This study shows why the conventional EKC model is not sufficient to ascertain the declining path of pollution as the economy grows in the second stage. The paper uses the modified EKC theory where the EKC curve is proposed to have 2 turning points. Our results indicated ‘tilted-S shaped’ relationship which contradicts EKC in the early stages. Most of the regions that were studied have crossed the first turning point but are still to cross the second turning point, which means that there will be an ascent in the pollution level in the future. This calls for more stringent environment policies complementing the desired growth path.     

Organochlorine pesticide residues in sediments of a tropical mangrove estuary,India: implications for monitoring

The paper examines the concentrations of isomers of hexachlorocyclohexane (HCHs), dichlorodiphenyl trichloroethane and its metabolites (DDTs), alpha-endosulfan and endosulfan sulfate in surface sediment samples collected from the mouth of Hugli estuary in the vicinity of Sundarban mangrove environment, eastern part of India. An overall pattern of accumulation of these pesticides was in the order of: SigmaHCH>endosulfan sulfate>SigmaDDT>alpha-endosulfan. The concentration of these compounds was quite low. An elevated level of SigmaHCH, SigmaDDT and endosulfan sulfate were marked during premonsoon months, a period characterized by high salinity and pH values. Among the isomers and metabolites of HCH and DDT, beta-HCH, pp'-DDT and pp'-DDE were found to be dominant. The sources of contamination are closely related to human activities, such as domestic and industrial discharges, agricultural chemical applications and soil erosion due to deforestation. The study is compared to other estuarine environment in India and abroad. The present data will serve as a baseline against which future anthropogenic effects may be assessed.     

Performance study and kinetic modeling of hybrid bioreactor for treatment of bi-substrate mixture of phenol-m-cresol in wastewater: Process optimization with response surface methodology

Performance of a hybrid reactor comprising of trickling filter(TF) and aeration tank(AT) unit was studied for biological treatment of wastewater containing mixture of phenol and m-cresol,using mixed microbial culture.The reactor was operated with hydraulic loading rates(HLR) and phenolics loading rates(PLR) between 0.222-1.078m3/(m2·day) and 0.900-3.456kg/(m3·day),respectively.The efficiency of substrate removal varied between 71%-100% for the range of HLR and PLR studied.The fixed film unit showed better substrate removal efficiency than the aeration tank and was more resistant to substrate inhibition.The kinetic parameters related to both units of the reactor were evaluated and their variation with HLR and PLR were monitored.It revealed the presence of substrate inhibition at high PLR both in TF and AT unit.The biofilm model established the substrate concentration profile within the film by solving differential equation of substrate mass transfer using boundary problem solver tool ’bvp4c’ of MATLAB 7.1 software.Response surface methodology was used to design and optimize the biodegradation process using Design Expert 8 software,where phenol and m-cresol concentrations,residence time were chosen as input variables and percentage of removal was the response.The design of experiment showed that a quadratic model could be fitted best for the present experimental study.Significant interaction of the residence time with the substrate concentrations was observed.The optimized condition for operating the reactor as predicted by the model was 230mg/L of phenol,190mg/L of m-cresol with residence time of 24.82 hr to achieve 99.92% substrate removal.     

Pesticide effects on microbial population and soil enzyme activities during vermicomposting of agricultural waste

The effects of different pesticides (propiconazole, profenofos, pretilachlor) on vermicomposting were evaluated for the adverse effects on soil enzyme activities (dehydrogenase, phosphatase, urease) and total microbial counts (TMC). There were remarkable increase in enzyme activities and TMC in presence of earthworm compared to control (earthworm absent). In comparison to control, the activities of phosphatase, dehydrogenase and urease in presence of vermicompost increased upto 30, 128 and 31.3% respectively; whereas increase of TMC was 71.9%. But, in presence of each of the pesticide, said activities decreased. Maximum inhibition of soil phosphatase activity (46.6%) was observed in presence of propiconazole (100 mg kg(-1)) after 120 days. Profenofos affected the soil dehydrogenase activity in the tune of 47% at 1000 mg kg(-1) concentration after 80 days and thereafter, the extent of toxicity decreased little. Soil urease activity was affected markedly in presence of profenofos and was 62% at 1000 mg kg(-1) level after 80 days. TMC also declined in presence of profenofos and pretilachlor. Increase in TMC was about 71.9% compared to control and the inhibition was more or less 60% when profenofos (1000 mg kg(-1)) was present even after 120 days of treatment.     

Comparative assessment of pesticide residues in grain, soil, and water from IPM and non-IPM trials of basmati rice

The integrated pest management (IPM) modules of pesticide schedule on Basmati rice were validated at field experiments conducted in Northern India for consecutive 3 years (2005–2008). The pesticide residues were found below the detectable limit (<0.01–0.001 mg/kg) in soil and irrigation water samples of Kaithal region. In Dehra Dun region of Uttrakhand, the residues of carbendazim in rice grains and soil were detected below <0.01 mg/kg level. In second year experiments (2006–2007), only four non-IPM soil samples indicated the presence of chlorpyrifos and endosulfan in the range of ND <0.001 to 0.07 mg/kg, out of 45 samples analyzed. Carbendazim applied as seed treatment at Dehradun and Kaithal field trials was found below detectable limit in both IPM and non-IPM rice grains (<0.01 mg/kg) and irrigation water (0.01 μl/ml). Chlorpyrifos was detected in five water samples from Kaithal and one from Pant Nagar in the range of 0.003–0.006 μl/L, α- and β-isomer of endosulfan in the range of 0.005–0.03, and 0.005–0.02 μl/ml, respectively, in one sample from Pant Nagar and two from Kaithal, out of a total of 22 samples. In the region of Uttrakhand and Uttar Pradesh during 2007–2008, four non-IPM samples of soil indicated trace levels of endosulfan, out of 16 samples analyzed. The residues were detected below detection limit for carbendazim (<0.01 mg/kg) in soil samples of Dehradun IPM fields and for endosulfan and carbendazim (0.001–0.01 μl/L) in water samples each from IPM and non-IPM fields of Uttar Pradesh. The results of 3-year trials of IPM module indicated basmati rice as safe and economical with pesticide residue-free rice grains.     

Assessment of water quality using multivariate statistical techniques in the coastal region of Visakhapatnam,India

The present study was intended to develop a Water Quality Index (WQI) for the coastal water of Visakhapatnam, India from multiple measured water quality parameters using different multivariate statistical techniques. Cluster analysis was used to classify the data set into three major groups based on similar water quality characteristics. Discriminant analysis was used to generate a discriminant function for developing a WQI. Discriminant analysis gave the best result for analyzing the seasonal variation of water quality. It helped in data reduction and found the most discriminant parameters responsible for seasonal variation of water quality. Coastal water was classified into good, average, and poor quality considering WQI and the nutrient load. The predictive capacity of WQI was proved with random samples taken from coastal areas. High concentration of ammonia in surface water during winter was attributed to nitrogen fixation by the phytoplankton bloom which resulted due to East India Coastal Current. This study brings out the fact that water quality in the coastal region not only depends on the discharge from different pollution sources but also on the presence of different current patterns. It also illustrates the usefulness of WQI for analyzing the complex nutrient data for assessing the coastal water and identifying different pollution sources, considering reasons for seasonal variation of water quality.     

Toxicity,uptake, and accumulation of nano and bulk cerium oxide particles in <Emphasis Type="Italic">Artemia salina</Emphasis>

Although the toxicological impact of metal oxide nanoparticles has been studied for the last few decades on aquatic organisms, the exact mechanism of action is still unclear. The fate, behavior, and biological activity of nanoparticles are dependent on physicochemical factors like size, shape, surface area, and stability in the medium. This study deals with the effect of nano and bulk CeO₂ particles on marine microcrustacean, Artemia salina. The primary size was found to be 15 ± 3.5 and 582 ± 50 nm for nano and bulk CeO₂ (TEM), respectively. The colloidal stability and sedimentation assays showed rapid aggregation of bulk particles in seawater. Both the sizes of CeO₂ particles inhibited the hatching rate of brine shrimp cyst. Nano CeO₂ was found to be more toxic to A. salina (48 h LC₅₀ 38.0 mg/L) when compared to bulk CeO₂ (48 h LC₅₀ 92.2 mg/L). Nano CeO₂-treated A. salina showed higher oxidative stress (ROS) than those treated with the bulk form. The reduction in the antioxidant activity indicated an increase in oxidative stress in the cells. Higher acetylcholinesterase activity (AChE) was observed upon exposure to nano and bulk CeO₂ particles. The uptake and accumulation of CeO₂ particles were increased with respect to the concentration and particle size. Thus, the above results revealed that nano CeO₂ was more lethal to A. salina as compared to bulk particles.