The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform

Glenda Garcia-santos - One of the best experts on this subject based on the ideXlab platform.

  • Review: Use of tracers to assess pesticide drift exposure in soil and human
    Exposure and Risk Assessment of Pesticide Use in Agriculture, 2021
    Co-Authors: Glenda Garcia-santos
    Abstract:

    Abstract The objective of this review is to fill the gap of knowledge on the use of tracers to assess fate of pesticide with particular focus on particle dispersion from drift airborne, soil deposits, and human exposure. For this a review of the use of tracers to study exposure of human and soil is presented and a case study in the Andean region serves here as the example of the use of Knapsack Sprayers in a mountainous area in Boyaca (Colombia).

  • Spatial interpolation methods to predict airborne pesticide drift deposits on soils using Knapsack Sprayers
    Chemosphere, 2020
    Co-Authors: Glenda Garcia-santos, Michael Scheiber, Jürgen Pilz
    Abstract:

    Spatial predictions of drift deposits on soil surface were conducted using eight different spatial interpolation methods i.e. classical approaches like the Thiessen method and kriging, and some advanced methods like spatial vine copulas, Karhunen-Loève expansion and INLA. In order to investigate the impact of the number of locations on the prediction, all spatial predictions were conducted using a set of 39 and 47 locations respectively. The analysis revealed that taking more locations into account increases the accuracy of the prediction and the extreme behavior of the data is better modeled. Leave-one-out cross-validation was used to assess the accuracy of the prediction. The Thiessen method has the highest prediction errors among all tested methods. Linear interpolation methods were able to better reproduce the extreme behavior at the first meters from the sprayed border and exhibited lower prediction errors as the number of data points increased. Especially the spatial copula method exhibited an obvious increase in prediction accuracy. The Karhunen-Loève expansion provided similar results as universal kriging and IDW, although showing a stronger change in the prediction as the number of locations increased. INLA predicted the pesticide dispersion to be smooth over the whole study area. Using Delaunay triangulation of the study area, the total pesticide concentration was estimated to be between 2.06% and 2.97% of the total Uranine applied. This work is a first attempt to completely understand and model the uncertainties of the mass balance, therefore providing a basis for future studies.

  • The weight method: a new screening method for estimating pesticide deposition from Knapsack Sprayers in developing countries.
    Chemosphere, 2010
    Co-Authors: Glenda Garcia-santos, Dominik Scheiben, Claudia R. Binder
    Abstract:

    Investigations of occupational and environmental risk caused by the use of agrochemicals have received considerable interest over the last decades. And yet, in developing countries, the lack of staff and analytical equipment as well the costs of chemical analyses make it difficult, if not impossible, to monitor pesticide contamination and residues in humans, air, water, and soils. A new and simple method is presented here for estimation of pesticide deposition in humans and soil after application. The estimate is derived on the basis of water mass balance measured in a given number of high absorbent papers under low evaporative conditions and unsaturated atmosphere. The method is presented as a suitable, rapid, low cost screening tool, complementary to toxicological tests, to assess occupational and environmental exposure caused by Knapsack Sprayers, where there is a lack of analytical instruments. This new method, called the "weight method", was tested to obtain drift deposition on the neighbouring field and the clothes of the applicator after spraying water with a Knapsack sprayer in one of the largest areas of potato production in Colombia. The results were confirmed by experimental data using a tracer and the same set up used for the weight method. The weight method was able to explain 86% of the airborne drift and deposition variance.

Stefan Peterson - One of the best experts on this subject based on the ideXlab platform.

  • Improved salt iodation methods for small-scale salt producers in low-resource settings in Tanzania
    BMC public health, 2009
    Co-Authors: Vincent Didas Assey, Thorkild Tylleskär, Philip B. Momburi, Michael Maganga, Nicholaus Mlingi, Marie Reilly, Ted Greiner, Stefan Peterson
    Abstract:

    Universal salt iodation will prevent iodine deficiency disorders (IDD). Globally, salt-iodation technologies mostly target large and medium-scale salt-producers. Since most producers in low-income countries are small-scale, we examined and improved the performance of hand and Knapsack-Sprayers used locally in Tanzania. We studied three salt facilities on the Bagamoyo coast, investigating procedures for preparing potassium-iodate solution, salt spraying and mixing. Different concentrations of solution were prepared and tested using different iodation methods, with the aim of attaining correct and homogeneous iodine levels under real-life conditions. Levels achieved by manual mixing were compared to those achieved by machine mixing. The overall median iodation level in samples of salt iodated using previously existing methods was 10.6 ppm (range 1.1 – 110.0 ppm), with much higher levels in the top than the bottom layers of the salt bags, p < 0.0001. Experimentation using Knapsack-Sprayers and manual mixing led to the reliable achievement of levels (60.9 ppm ± 7.4) that fell within the recommended range of 40 – 80 ppm. The improved methods yielded homogenous iodine concentrations in all layers of salt-bags (p = 0.58) with 96% of the samples (n = 45) falling within 40 – 80 ppm compared to only 9% (n = 45) before the experiment and training (p < 0.0001). For Knapsack-spraying, a machine mixer improved the iodine levels and homogeneity slightly compared to manual mixing (p = 0.05). Supervised, standardized salt iodation procedures adapted to local circumstances can yield homogeneous iodine levels within the required range, overcoming a major obstacle to universal salt iodation.

Jürgen Pilz - One of the best experts on this subject based on the ideXlab platform.

  • spatial interpolation methods to predict airborne pesticide drift deposits on soils using Knapsack Sprayers
    Chemosphere, 2020
    Co-Authors: Glenda Garciasantos, Michael Scheiber, Jürgen Pilz
    Abstract:

    Abstract Spatial predictions of drift deposits on soil surface were conducted using eight different spatial interpolation methods i.e. classical approaches like the Thiessen method and kriging, and some advanced methods like spatial vine copulas, Karhunen-Loeve expansion and INLA. In order to investigate the impact of the number of locations on the prediction, all spatial predictions were conducted using a set of 39 and 47 locations respectively. The analysis revealed that taking more locations into account increases the accuracy of the prediction and the extreme behavior of the data is better modeled. Leave-one-out cross-validation was used to assess the accuracy of the prediction. The Thiessen method has the highest prediction errors among all tested methods. Linear interpolation methods were able to better reproduce the extreme behavior at the first meters from the sprayed border and exhibited lower prediction errors as the number of data points increased. Especially the spatial copula method exhibited an obvious increase in prediction accuracy. The Karhunen-Loeve expansion provided similar results as universal kriging and IDW, although showing a stronger change in the prediction as the number of locations increased. INLA predicted the pesticide dispersion to be smooth over the whole study area. Using Delaunay triangulation of the study area, the total pesticide concentration was estimated to be between 2.06% and 2.97% of the total Uranine applied. This work is a first attempt to completely understand and model the uncertainties of the mass balance, therefore providing a basis for future studies.

  • Spatial interpolation methods to predict airborne pesticide drift deposits on soils using Knapsack Sprayers
    Chemosphere, 2020
    Co-Authors: Glenda Garcia-santos, Michael Scheiber, Jürgen Pilz
    Abstract:

    Spatial predictions of drift deposits on soil surface were conducted using eight different spatial interpolation methods i.e. classical approaches like the Thiessen method and kriging, and some advanced methods like spatial vine copulas, Karhunen-Loève expansion and INLA. In order to investigate the impact of the number of locations on the prediction, all spatial predictions were conducted using a set of 39 and 47 locations respectively. The analysis revealed that taking more locations into account increases the accuracy of the prediction and the extreme behavior of the data is better modeled. Leave-one-out cross-validation was used to assess the accuracy of the prediction. The Thiessen method has the highest prediction errors among all tested methods. Linear interpolation methods were able to better reproduce the extreme behavior at the first meters from the sprayed border and exhibited lower prediction errors as the number of data points increased. Especially the spatial copula method exhibited an obvious increase in prediction accuracy. The Karhunen-Loève expansion provided similar results as universal kriging and IDW, although showing a stronger change in the prediction as the number of locations increased. INLA predicted the pesticide dispersion to be smooth over the whole study area. Using Delaunay triangulation of the study area, the total pesticide concentration was estimated to be between 2.06% and 2.97% of the total Uranine applied. This work is a first attempt to completely understand and model the uncertainties of the mass balance, therefore providing a basis for future studies.

Vincent Didas Assey - One of the best experts on this subject based on the ideXlab platform.

  • Improved salt iodation methods for small-scale salt producers in low-resource settings in Tanzania
    BMC public health, 2009
    Co-Authors: Vincent Didas Assey, Thorkild Tylleskär, Philip B. Momburi, Michael Maganga, Nicholaus Mlingi, Marie Reilly, Ted Greiner, Stefan Peterson
    Abstract:

    Universal salt iodation will prevent iodine deficiency disorders (IDD). Globally, salt-iodation technologies mostly target large and medium-scale salt-producers. Since most producers in low-income countries are small-scale, we examined and improved the performance of hand and Knapsack-Sprayers used locally in Tanzania. We studied three salt facilities on the Bagamoyo coast, investigating procedures for preparing potassium-iodate solution, salt spraying and mixing. Different concentrations of solution were prepared and tested using different iodation methods, with the aim of attaining correct and homogeneous iodine levels under real-life conditions. Levels achieved by manual mixing were compared to those achieved by machine mixing. The overall median iodation level in samples of salt iodated using previously existing methods was 10.6 ppm (range 1.1 – 110.0 ppm), with much higher levels in the top than the bottom layers of the salt bags, p < 0.0001. Experimentation using Knapsack-Sprayers and manual mixing led to the reliable achievement of levels (60.9 ppm ± 7.4) that fell within the recommended range of 40 – 80 ppm. The improved methods yielded homogenous iodine concentrations in all layers of salt-bags (p = 0.58) with 96% of the samples (n = 45) falling within 40 – 80 ppm compared to only 9% (n = 45) before the experiment and training (p < 0.0001). For Knapsack-spraying, a machine mixer improved the iodine levels and homogeneity slightly compared to manual mixing (p = 0.05). Supervised, standardized salt iodation procedures adapted to local circumstances can yield homogeneous iodine levels within the required range, overcoming a major obstacle to universal salt iodation.

Glenda Garciasantos - One of the best experts on this subject based on the ideXlab platform.

  • spatial interpolation methods to predict airborne pesticide drift deposits on soils using Knapsack Sprayers
    Chemosphere, 2020
    Co-Authors: Glenda Garciasantos, Michael Scheiber, Jürgen Pilz
    Abstract:

    Abstract Spatial predictions of drift deposits on soil surface were conducted using eight different spatial interpolation methods i.e. classical approaches like the Thiessen method and kriging, and some advanced methods like spatial vine copulas, Karhunen-Loeve expansion and INLA. In order to investigate the impact of the number of locations on the prediction, all spatial predictions were conducted using a set of 39 and 47 locations respectively. The analysis revealed that taking more locations into account increases the accuracy of the prediction and the extreme behavior of the data is better modeled. Leave-one-out cross-validation was used to assess the accuracy of the prediction. The Thiessen method has the highest prediction errors among all tested methods. Linear interpolation methods were able to better reproduce the extreme behavior at the first meters from the sprayed border and exhibited lower prediction errors as the number of data points increased. Especially the spatial copula method exhibited an obvious increase in prediction accuracy. The Karhunen-Loeve expansion provided similar results as universal kriging and IDW, although showing a stronger change in the prediction as the number of locations increased. INLA predicted the pesticide dispersion to be smooth over the whole study area. Using Delaunay triangulation of the study area, the total pesticide concentration was estimated to be between 2.06% and 2.97% of the total Uranine applied. This work is a first attempt to completely understand and model the uncertainties of the mass balance, therefore providing a basis for future studies.

  • drift from the use of hand held Knapsack pesticide Sprayers in boyaca colombian andes
    Journal of Agricultural and Food Chemistry, 2016
    Co-Authors: Glenda Garciasantos, Giuseppe Feola, David Nuyttens, Jaime Diaz
    Abstract:

    Offsite pesticide losses in tropical mountainous regions have been little studied. One example is measuring pesticide drift soil deposition, which can support pesticide risk assessment for surface water, soil, bystanders, and off-target plants and fauna. This is considered a serious gap, given the evidence of pesticide-related poisoning in those regions. Empirical data of drift deposition of a pesticide surrogate, Uranine tracer, within one of the highest potato-producing regions in Colombia, characterized by small plots and mountain orography, is presented. High drift values encountered in this study reflect the actual spray conditions using hand-held Knapsack Sprayers. Comparison between measured and predicted drift values using three existing empirical equations showed important underestimation. However, after their optimization based on measured drift information, the equations showed a strong predictive power for this study area and the study conditions. The most suitable curve to assess mean relativ...