Evaluation of pesticide impact rating index (PIRI) model as a pesticide risk indicator

Systematic methods for assessment of potential risk of pesticides to the environment can be consideredas valuable tools in decision-making and policy formulation. Pesticide Impact Rating Index (PIRI) isa user-friendly simple risk indicator and it can be used to rank pesticides in terms of their mobility. Thepredictions given by using PIRI for the pollution potential of pesticides on shallow ground waterbodies of Kalpitiya area in Sri Lanka was compared with the field experiments. Cultivated areas ofKalpitiya peninsula were selected for field trials.Oxytluorfen for onions, Chlorpyrifos, Diazinon, Dimethoate, Carbofuran, Carbaryl, Mcthornyl,Irnidacloprid, Fenthion and Captan for chili were applied in replicates at recommended applicationrates for particular crops. Each area was irrigated at the rate of 20 mm/day. The soil considered wasthe sandy soil with the organic matter of 1.6±0.2%. Residue levels of applied pesticides were measuredusing Gas Chromatographic and High Performance Liquid Chromatographi methods in irrigation wellsin 100 m diameter area at 3 m depth for 3 months in one week intervals from the time of pesticideapplication. The detected pesticides were confirmed using Gas Chromatographic MassSpectrophotometric method.Out of applied pesticides, Dirnethoate, Carbofuran, and Chlorpyrifos leached 3 m water table in 24±4days, 25±3 days and 3 5±6 days respectively after application of each pesticide. The field monitoringresults were 74% compatible with the predictions from PIRI. This indicates that PIRI can be used asa simple risk indicator model for the prediction of pesticide risk to water bodies.

Developing an economic, environmental and agronomic case for the increased use of organic amendments in South Asia

Aggressive fertilizer subsidies throughout South Asia have led to a rapid increase in the use of synthetic nitrogen fertilizers such as urea at the farm level. While this has been successful in increasing yields, significant yield gaps remain between potential and actual farm yields, while unbalanced or over application of fertilizers potentially damages soil and environmental health. This project examined organic amendment (OA) application in India and Sri Lanka on productivity, soil properties and greenhouse gas emissions. In India, poultry, farm-yard manure and vermi-compost were applied to a paddy rice crop, and the potential benefits followed through to a post-rice chickpea crop. In Sri Lanka, we tested the optimal combination of synthetic nitrogen fertilizer rates when using municipal-waste compost in a multi-year maize-soybean rotation. Results at both trial sites saw an increase in crop yields under OA application; in particular chickpea yields from farm-yard manure and after repeated application of municipal-waste compost. However, all OA treatments increased emissions of the greenhouse gases nitrous oxide and methane due to additional nitrogen or carbon availability. Furthermore, the low nutrient content and relatively high cost of the OA’s, particularly the composts, made them uneconomical as nutrient sources compared to conventional fertilizers

Interfacial-Redox-Induced Tuning of Superconductivity in YBa2Cu3O7-δ.

Solid-state ionic approaches for modifying ion distributions in getter/oxide heterostructures offer exciting potentials to control material properties. Here, we report a simple, scalable approach allowing for manipulation of the superconducting transition in optimally doped YBa2Cu3O7-δ (YBCO) films via a chemically driven ionic migration mechanism. Using a thin Gd capping layer of up to 20 nm deposited onto 100 nm thick epitaxial YBCO films, oxygen is found to leach from deep within the YBCO. Progressive reduction of the superconducting transition is observed, with complete suppression possible for a sufficiently thick Gd layer. These effects arise from the combined impact of redox-driven electron doping and modification of the YBCO microstructure due to oxygen migration and depletion. This work demonstrates an effective step toward total ionic tuning of superconductivity in oxides, an interface-induced effect that goes well into the quasi-bulk regime, opening-up possibilities for electric field manipulation

Structural, elastic and thermal properties of cementite (Fe3_3C) calculated using Modified Embedded Atom Method

Structural, elastic and thermal properties of cementite (Fe$_3$C) were studied using a Modified Embedded Atom Method (MEAM) potential for iron-carbon (Fe-C) alloys. Previously developed Fe and C single element potentials were used to develop an Fe-C alloy MEAM potential, using a statistically-based optimization scheme to reproduce structural and elastic properties of cementite, the interstitial energies of C in bcc Fe as well as heat of formation of Fe-C alloys in L$_{12}$ and B$_1$ structures. The stability of cementite was investigated by molecular dynamics simulations at high temperatures. The nine single crystal elastic constants for cementite were obtained by computing total energies for strained cells. Polycrystalline elastic moduli for cementite were calculated from the single crystal elastic constants of cementite. The formation energies of (001), (010), and (100) surfaces of cementite were also calculated. The melting temperature and the variation of specific heat and volume with respect to temperature were investigated by performing a two-phase (solid/liquid) molecular dynamics simulation of cementite. The predictions of the potential are in good agreement with first-principles calculations and experiments.Comment: 12 pages, 9 figure

RISK ASSESSMENT OF PESTICIDE CONTAMINATION POTENTIALS IN EMBILlPITlYA AREA

Embilipitiya is a highly agricultural area, which has consumed a remarkable amount ofagrochemicals in last two decades. Hence pesticide movement level studies are necessaryto prevent the contamination of soil and water by these pesticides.Pesticides Impact Ranking Index (pIRI) is a simple computation model, which can beused for ranking pesticides according to their leaching ability and toxicity levels. Itrequires soil and climatic parameters. chemical and application information of pesticides,etc. The risk levels are indicated as very low, low, medium, high, very high andextremely high according to their leaching and toxicity conditionsThe modeling using PIRI was carried out to rank the most widely used three pesticides,3,4 DPA, Carbfuran and MCPA, for 14 different soil series present in Embilipitiya area.The risk level frequencies were calculated for each pesticide. For 8 soil series high riskleaching potential was obtained. Carbofuran and Walawa series has extremely highleaching potential than others. In comparison, MCPA has a medium risk potential for 10soil series. 3,4 DPA has a very low leaching potential for all soils.Toxicity levels obtained for most of the soil series are low except for Thimbolketiya andWalawa soil series. They have high and medium toxicity levels respectively forcarbofuran. Hence the risk level of carbofuran is very high, MCPA is medium and 3,4DPA is low in different soils present in Embilipitiya area and therefore the usage ofCarbofuran needs to be controlled. In pesticide usage and selection, extra care andawareness procedures are necessary to prevent ground water contamination in future

Weak charge form factor and radius of 208Pb through parity violation in electron scattering

We use distorted wave electron scattering calculations to extract the weak charge form factor F_W(q), the weak charge radius R_W, and the point neutron radius R_n, of 208Pb from the PREX parity violating asymmetry measurement. The form factor is the Fourier transform of the weak charge density at the average momentum transfer q=0.475 fm$^{-1}$. We find F_W(q) =0.204 \pm 0.028 (exp) \pm 0.001 (model). We use the Helm model to infer the weak radius from F_W(q). We find R_W= 5.826 \pm 0.181 (exp) \pm 0.027 (model) fm. Here the exp error includes PREX statistical and systematic errors, while the model error describes the uncertainty in R_W from uncertainties in the surface thickness \sigma of the weak charge density. The weak radius is larger than the charge radius, implying a "weak charge skin" where the surface region is relatively enriched in weak charges compared to (electromagnetic) charges. We extract the point neutron radius R_n=5.751 \pm 0.175 (exp) \pm 0.026 (model) \pm 0.005 (strange) fm$, from R_W. Here there is only a very small error (strange) from possible strange quark contributions. We find R_n to be slightly smaller than R_W because of the nucleon's size. Finally, we find a neutron skin thickness of R_n-R_p=0.302\pm 0.175 (exp) \pm 0.026 (model) \pm 0.005 (strange) fm, where R_p is the point proton radius.Comment: 5 pages, 1 figure, published in Phys Rev. C. Only one change in this version: we have added one author, also to metadat