Organochlorine and organophosphorous pesticide residues in ground water and surface waters of Kanpur, Uttar Pradesh, India

A survey undertaken in Kanpur, northern India, has shown the presence of high concentrations of both organochlorine and organophosphorous pesticides in the surface and ground water samples. Liquid-liquid extraction followed by GC-ECD was used for the determination of these compounds. Among the various pesticides analyzed, high concentrations of gamma-HCH (0.259 microg/l) and malathion (2.618 microg/l) were detected in the surface water samples collected from the River Ganges in Kanpur. In the ground water samples collected from the various hand pumps located in agricultural and industrial areas, apart from gamma-HCH and malathion, dieldrin was also detected. The maximum concentration values of gamma-HCH, malathion and dieldrin were 0.900, 29.835 and 16.227 microg/l, respectively. Especially, the concentration of malathion was found to be much higher than the EC water quality standards in the ground water samples from industrial area posing a high risk to the common people. Pesticides like DDE, DDT, aldrin, ethion, methyl parathion and endosulfan were not detected in both the surface and ground water samples.     

Modeling watershed-scale effectiveness of agricultural best management practices to reduce phosphorus loading

Planners advocate best management practices (BMPs) to reduce loss of sediment and nutrients in agricultural areas. However, the scientific community lacks tools that use readily available data to investigate the relationships between BMPs and their spatial locations and water quality. In rural, humid regions where runoff is associated with saturation-excess processes from variable source areas (VSAs), BMPs are potentially most effective when they are located in areas that produce the majority of the runoff. Thus, two critical elements necessary to predict the water quality impact of BMPs include correct identification of VSAs and accurate predictions of nutrient reduction due to particular BMPs. The objective of this research was to determine the effectiveness of BMPs using the Variable Source Loading Function (VSLF) model, which captures the spatial and temporal evolutions of VSAs in the landscape. Data from a long-term monitoring campaign on a 164-ha farm in the New York City source watersheds in the Catskills Mountains of New York state were used to evaluate the effectiveness of a range of BMPs. The data spanned an 11-year period over which a suite of BMPs, including a nutrient management plan, riparian buffers, filter strips and fencing, was installed to reduce phosphorus (P) loading. Despite its simplicity, VSLF predicted the spatial distribution of runoff producing areas well. Dissolved P reductions were simulated well by using calibrated reduction factors for various BMPs in the VSLF model. Total P losses decreased only after cattle crossings were installed in the creek. The results demonstrated that BMPs, when sited with respect to VSAs, reduce P loss from agricultural watersheds, providing useful information for targeted water quality management.     

Chemical tracers as indicator of human fecal coliforms at storm water outfalls

Indicators to distinguish between fecal coliforms of human and animal origin were investigated in water from storm sewer outfalls to a coastal lake during wet and dry weather. The ratio of fecal coliform relative to fecal streptococci count was used as the microbiological indicator. Concentrations of human-activities originated caffeine, anionic surfactant, fluoride, and fluorescence whitening agent (FWA) were used as chemical indicators. The ratio of fecal coliform to fecal streptococci ranged from 0.2 to 3.0, during wet weather making it difficult to interpret the origin of fecal pollution. However, concentrations of caffeine, anionic surfactant, fluoride, and FWA in storm water outflow during wet weather were much higher than those in the lake water during dry weather, indicating the presence of human waste at storm water outfall. Strong correlation between fecal coliform counts and chemical parameter values further indicated the human contribution to the fecal coliform count. In addition, a strong correlation among the chemical parameters suggested that only one of them is needed as chemical tracer to detect the presence of human input.     

Contamination of nitrate and fluoride in ground water along the Ganges Alluvial Plain of Kanpur district, Uttar Pradesh, India

Nitrate-N and Fluoride concentrations were analyzed in shallow and unconfined ground water aquifers of Kanpur district along the Ganges Alluvial Plain of Northern India. Kanpur district was divided into three zones namely, Bithore, Kanpur City and Beyond Jajmau and sampling was carried out three seasons (summer, monsoon and winter). The data set consisted of the results of water samples from around 99 India Mark II hand Pumps, which were analyzed for summer monsoon and winter seasons. In Bithore zone, 19% of the samples exceeded the BIS (Bureau of India Standards) limit 10.2 mg/l as nitrate-N and as high as 166 mg/l as nitrate-N was observed. 10% and 7% samples in Kanpur city and beyond Jajmau zone respectively, exceeded the BIS limit. The Frequency distribution histogram of nitrate-N revealed a skewed (non-normal) distribution. Both point and non-point sources contribute to the ground water contamination. Especially in Bithore zone, the point sources could be attributed to the animal wastes derived from cows and buffaloes and non point sources could be due to the extensive agricultural activity prevalent in that area. Fluoride concentration in most samples was within the BIS maximum permissible level of 1.5 mg/l. No significant seasonal variation in water quality parameters was observed.     

Geochemistry and mobilization of arsenic in Shuklaganj area of Kanpur–Unnao district, Uttar Pradesh, India

The level of arsenic (As) contamination and the geochemical composition of groundwater in Shuklaganj area located on the banks of the Ganges Delta of Kanpur-Unnao district were elucidated. Samples (n?=?59) were collected from both India Mark II hand pumps (depth, 30-33 m) and domestic hand pump tube wells (10-12 m) located within 5 km from the banks of Ganges. Samples were analyzed for various parameters, including total inorganic As, sulfate, nitrate, alkalinity, ammonia, and iron. Hydrochemistry of the groundwater aquifer was studied through the trilinear plots between monovalent and divalent cations and anions. In Indian mark II hand pumps, arsenic concentration ranged from below detection limit to 448 μg/L. Most of the samples contained both As(III) and As(V). The pH of the samples ranged from 7.1 to 8.2. Except for a few, most of the samples were reducing in nature as evident by their negative oxidation reduction potentials. A positive correlation for arsenic with iron, ammonia, and dissolved organic carbon shows the probability of biodegradation of organic matter and reductive dissolution of Fe oxyhydroxide processes to leach As in aquifers. For confirmation of the suggested arsenic mobilization mechanism, the presence and absence of sulfate-reducing bacteria and iron-reducing bacteria were also tested.     

Effect of mycosynthesized silver nanoparticles from filtrate of Trichoderma harzianum against larvae and pupa of dengue vector Aedes aegypti L

Mosquitoes transmit dreadful diseases, causing millions of deaths every year. Therefore, screening for larvicidal and pupicidal activity of microbial extracts attributes could lead to development of new and improved mosquito control methods that are economical and safe for nontarget organisms and are ecofriendly. Synthetic chemical insecticides occupy predominant position in control strategies. These hazardous chemicals exert unwarranted toxicity and lethal effects on nontarget organisms, develop physiological resistance in target, and cause adverse environmental effect. For vector control, fungal-mediated natural products have been a priority in this area at present. In the current study, effective larvicidal and pupicidal effect of mycosynthesized silver nanoparticles (Ag NPs) using an entomopathogenic fungi Trichoderma harzianum against developmental stages of the dengue vector Aedes aegypti was investigated. An attractive possibility of green nanotechnology is to use microorganisms in the synthesis of nanosilver especially Ag NPs. The mycosynthesized Ag NPs were characterized to find their unique properties through UV-visible spectrophotometer, X-ray diffraction analysis, Fourier transform infrared, and surface characteristics by scanning electron microscopy. To analyze the bioefficacy, different test concentrations for extracellular filtrate (0.2, 0.4, 0.6, 0.8, and 1.0 %) and Ag NPs (0.05, 0.10, 0.15, 0.20, and 0.25 %) were prepared to a final volume of 200 mL using deionized water; 20 larvae of each instars (I–IV) and pupa were exposed to each test concentration separately which included a set of control (distilled water) group with five replicates. Characterization of the synthesized Ag NPs were about 10–20 nm without aggregation. Susceptibility of larval instars to synthesized Ag NPs was higher than the extracellular filtrate of T. harzianum alone after 24-h exposure, where the highest mortality was recorded as 92 and 96 % for first and second instars and 100 % for third, fourth instars, and pupa. Lethal concentration 50 values of 0.079, 0.084, 0.087, 0.068, and 0.026 % were recorded for I–IV instars and pupa, respectively, when exposed to Ag NPs at 0.25 % concentration. Toxicity was exhibited against first (1.076 %), second (0.912 %), third (0.770 %), fourth (0.914 %) instars larvae, and pupa (0.387 %) with extracellular filtrate at a concentration of 1 % that was three- to fourfold higher compared to Ag NPs; no mortality was observed in the control. The present study is the first report on effective larvicidal and pupicidal activity of Ag NPs synthesized from an entomopathogenic fungi T. harzianum extracellular filtrate and could be an ideal ecofriendly, single-step, and inexpensive approach for the control of A. aegypti.     

Role of extracellular compounds in Cd-sequestration relative to Cd uptake by bacterium Sinorhizobium meliloti

The role of bacterially derived compounds in Cd(II) complexation and uptake by bacterium Sinorhizobium meliloti wild type (WT) and genetically modified ExoY-mutant, deficient in exopolysaccharide production, was explored combining chemical speciation measurements and assays with living bacteria. Obtained results demonstrated that WT- and ExoY-strains excreted siderophores in comparable amounts, while WT-strain produced much higher amount of exopolysaccharides and less exoproteins. An evaluation of Cd(II) distribution in bacterial suspensions under short term exposure conditions, showed that most of the Cd is bound to bacterial surface envelope, including Cd bound to the cell wall and to the attached extracellular polymeric substances. However, the amount of Cd bound to the dissolved extracellular compounds increases at high Cd(II) concentrations. The implications of these findings to more general understanding of the Cd(II) fate and cycling in the environment is discussed.     

Novel chitosan/PVA/zerovalent iron biopolymeric nanofibers with enhanced arsenic removal applications

Enhanced removal application of both forms of inorganic arsenic from arsenic-contaminated aquifers at near-neutral pH was studied using a novel electrospun chitosan/PVA/zerovalent iron (CPZ) nanofibrous mat. CPZ was carefully examined using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), atomic fluorescence spectroscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). Application of the adsorbent towards the removal of total inorganic arsenic in batch mode has also been studied. A suitable mechanism for the adsorption has also been discussed. CPZ nanofibers mat was found capable to remove 200.0?±?10.0 mg g^?1 of As(V) and 142.9?±?7.2 mg g^?1 of As(III) from aqueous solution of pH 7.0 at ambient condition. Addition of ethylenediaminetetraacetic acid (EDTA) enabled the stability of iron in zerovalent state (ZVI). Enhanced capacity of the fibrous mat could be attributed to the high surface area of the fibers, presence of ZVI, and presence of functional groups such as amino, carboxyl, and hydroxyl groups of the chitosan and EDTA. Both Langmuir and Freundlich adsorption isotherms were applicable to describe the removal process. The possible mechanism of adsorption has been explained in terms of electrostatic attraction between the protonated amino groups of chitosan/arsenate ions and oxidation of arsenite to arsenate by Fentons generated from ZVI and subsequent complexation of the arsenate with the oxidized iron. These CPZ nanofibrous mats has been prepared with environmentally benign naturally occurring biodegradable biopolymer chitosan, which offers unique advantage in the removal of arsenic from contaminated groundwater.     

Zerovalent iron encapsulated chitosan nanospheres - a novel adsorbent for the removal of total inorganic arsenic from aqueous systems

Evaluation of Chitosan zerovalent Iron Nanoparticle (CIN) towards arsenic removal is presented. Addition of chitosan enhances the stability of Fe(0) nano particle. Prepared adsorbent was characterized by FT-IR, SEM EDX, BET and XRD. It was found that, with an initial dose rate of 0.5 g L⁻¹, concentrations of As (III) and As (V) were reduced from 2 mg L⁻¹ to <5 μg L⁻¹ in less than 180 min and the adsorbent was found to be applicable in wide range of pH. Langmuir monolayer adsorption capacity was found to be 94 ± 1.5 mg g⁻¹ and 119 ± 2.6 mg g⁻¹ at pH 7 for As (III) and As (V) respectively. Major anions including sulfate, phosphate and silicate did not cause significant interference in the adsorption behavior of both arsenite and arsenate. The adsorbent was successfully recycled five times and applied to the removal of total inorganic arsenic from real life groundwater samples.