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.     

Pesticides residues in vegetables in and around Delhi

This article presents the development of a multiresidue method forthe estimation of 30 insecticides, 15 organochlorineinsecticides and 6 organophosphorus insecticides, 9 syntheticpyrethriods and 2 herbicides and their quantificationin vegetables. The monitoring study indicates that though allthe vegetable samples were contaminated with pesticides, only31% of the samples contained pesticides above the prescribedtolerance limit.     

A simple chemical method for the synthesis of Cu2+ engrafted MgAl2O4 nanoparticles: Efficient fluoride adsorbents, photocatalyst and latent fingerprint detection

An adaptable, energy efficient chemical process is employed to synthesize Cu~(2+)engrafted MgAl_2O_4 nanoparticles(Mg_(1-x)Cu_xAl_2O_4, x = 0, 0.1, 0.3, 0.5 abbreviated as MCA0, MCA1, MCA3,and MCA5 respectively), using chelating ligand and the calcination temperature was determined by the thermogravimetric analysis of the precursor mass.They acted as good fluoride adsorbent in the presence of co-ions, different pH(2–11) via chemisorption revealed from Fourier-transform infrared spectroscopy(FTIR) and photodegraded Methylene Blue(MB).The satisfactory results were for MCA1(specific surface area 25.05 m~2/g) with 97%fluoride removal at pH 7.0 for the 10 mg/L initial fluoride concentration for 1.5 g/L adsorbent dose with 45 min contact time obeying the Langmuir isotherm model with negative thermodynamic parameters and 4 mmol of MCA3 with 98.51% photodegradation for 10~(-5) mol/L MB solution obeying pseudo-second-order and pseudo-first-order kinetics respectively.The proposed photodegradation mechanism of MB was established by the FTIR and high-performance liquid chromatography(HPLC) analysis.The nanoparticles are cubic, estimated through X-ray diffraction(XRD) and transmission electron microscopy(TEM) analysis.The band gap energies, grain size, and the effective working pH were estimated by diffuse reflectance spectra(DRS), scanning electron microscope(SEM), and zero-point potential analysis respectively.A soil candle with MCA1 also fabricated for the household purpose and tested with some fluorinated field samples.The MCA3 was able to enhance the latent fingerprint on smooth surfaces.     

Air quality analysis and indexing of Kolkata city with respect to vertical floor heights and seasonal variation

Air pollution is one of the most important global environmental issues. Urban air quality is generally becoming vulnerable especially in the developing countries due to various developmental activities. Several national and international studies prove that air pollution is harmful to human health and its long term exposure contributes to even mortality. Current study has been designed to determine the vertical floor wise air quality status of the city of Kolkata and the seasonal variation of the pollutants during two consecutive years. Particulate matter (PM₁₀ and suspended particulate matter), oxides of nitrogen, sulfur dioxide and carbon monoxide were analyzed for a total number of 135 air quality samples throughout the study area and period. Pollutants were found positively correlated with each other and with the floor heights. According to the air quality indexing, all the places were found affected from moderate to severe air pollution irrespective of the vertical floor heights, seasons and places. Although, no such seasonal trend has been emerged from the study but the number of samples beyond standard is found highest during the winter season followed by pre-monsoon.     

Decreased pH does not alter metamorphosis but compromises juvenile calcification of the tube worm Hydroides elegans

Using CO₂ perturbation experiments, we examined the pre- and post-settlement growth responses of a dominant biofouling tubeworm (Hydroides elegans) to a range of pH. In three different experiments, embryos were reared to, or past, metamorphosis in seawater equilibrated to CO₂ values of about 480 (control), 980, 1,480, and 2,300 μatm resulting in pH values of around 8.1 (control), 7.9, 7.7, and 7.5, respectively. These three decreased pH conditions did not affect either embryo or larval development, but both larval calcification at the time of metamorphosis and early juvenile growth were adversely affected. During the 24-h settlement assay experiment, half of the metamorphosed larvae were unable to calcify tubes at pH 7.9 while almost no tubes were calcified at pH 7.7. Decreased ability to calcify at decreased pH may indicate that these calcifying tubeworms may be one of the highly threatened species in the future ocean.     

Effect of the herbicides oxadiazon and oxyfluorfen on phosphates solubilizing microorganisms and their persistence in rice fields

A field experiment has been conducted with two herbicides viz. oxadiazon [5-terbutyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-one] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenyl)-4-(trifluoromethyl) benzene] at rates of 0.4 and 0.12 kg a.i. ha(-1), respectively, to investigate their effect on the growth and activities of phosphate solubilizing microorganisms in relation to availability of phosphorus as well as persistence of the herbicides in the rhizosphere soil of wetland rice (Oryza sativa L. variety IR-36). Application of herbicides stimulated the population and activities of phosphate solubilizing microorganisms and also the availability of phosphorus in the rhizosphere soil. Oxyfluorfen provided greater microbial stimulation than oxadiazon. Dissipation of oxyfluorfen and oxadiazon followed first order reaction kinetics with half-life (T(1/2)) of 8.8 and 12 days, respectively. Sixty days after application 0.5% and 3% of the applied oxadiazon and oxyfluorfen residues persisted, respectively, in the rhizosphere soil of rice.     

Water quality of the River Ganga (The Ganges) and some of its physico-chemical properties

Summary The water qualities of the River Ganga (The Ganges) over a short stretch from Swarupganj to Barrackpore (in West Bengal) have been determined and are compared with the values reported by the National Environmental Engineering Research Institute of India for the periods 1972–74 and 1979–80. The water quality is generally bad, but not at such alarming levels as previously determined by other agencies. Biochemical and chemical oxygen demand (BOD and COD) levels are high but within tolerable limits. Dissolved oxygen (DO) levels are are fairly high, indicating a reasonable self-purifying capability for the River Ganga. However, nutrient loads containing N and P have increased enormously in recent years.     

Studies on degradation of 14C-chlorpyrifos in the marine environment.

Degradation of 14C-chlorpyrifos was studied in a marine ecosystem for 60 days and in marine sediment under moist and flooded conditions using a continuous flow system allowing a total 14C-mass balance for a period of 40 days. In the marine ecosystem, 14C-chlorpyrifos underwent rapid degradation and very little (1-2%) 14C-residues of the applied activity were detected after two months in sediments. Clams were major component of the ecosystem and played a significant role in degradation of the insecticide. In the continuous flow system chlorpyrifos did not undergo substantial mineralization. Volatilization accounted for 0.8-1% loss during first ten days of application. The amounts of extractable 14C-activity were higher in flooded sediments than in moist sediment. More bound residues were formed under moist conditions. TCP (3,5,6-trichloro-2-pyridinol) was the major degradation product formed under both moist and flooded conditions, its formation being higher in the latter conditions. These studies underline the role of clams in degradation of chlorpyrifos and lack of microbial degradation. In absence of clams, chlorpyrifos underwent abiotic degradation in marine sediment with formation of bound residues.