Validation of a small-scale portable rainfall simulator on the simultaneous transport of sediments and pesticides in agriculture soils.

Background: Soil erosion and sedimentation accelerate land degradation, especially in East Asia. Surface runoff is a major pathway for pesticide transport into surface and groundwater, threatening aquatic ecosystems. This study investigated the runoff rate, sediment yield, pesticide transport, and pesticide concentrations across soil layers using a small-scale portable rainfall simulator (0.

Modelling pesticide concentrations in Japanese paddy fields using the RICEWQ model.

Increasing concerns about plant protection products in surface waters have highlighted the importance of pesticide monitoring and modelling, both nowadays integral components of the pesticide registration process. The Rice Water Quality (RICEWQ) model predicts the fate and transport of pesticides under various paddy environmental conditions. The model has been used widely for regulatory purpose in the U.

Assessment of agricultural pesticide inert ingredient transport following modeling approach: Case study of two formulation agents in Sacramento River watershed.

This research provides the first assessment of the environmental fate and transport of agricultural pesticide formulation agents following a dynamic modeling approach. Two formulation agents of toxicological concern, Naphthalene and Solvent Naphtha (Petroleum), Heavy Aromatic, were simulated from their usage in commercially-applied pesticides. The Soil and Water Assessment Tool (SWAT) was applied to simulate these formulation agents during 2011-2014 in the agriculturally intensive Sacramento River watershed.

Predicting rice pesticide fate and transport following foliage application by an updated PCPF-1 model.

The Pesticide Concentration in Paddy Field (PCPF-1) model has been successfully used to predict the fate and transport of granular pesticides applied to the paddy fields. However, it is not applicable for pesticides in foliar formulation while previous studies have reported that foliar application may increase the risks of rice pesticide contamination to the aquatic environment due to pesticide wash-off from rice foliage. In this study, we developed and added a foliar application module into the PCPF-1 model to improve its versatility regarding pesticide application methods.

Modeling of runoff water and runoff pesticide concentrations in upland bare soil using improved SPEC model.

The SPEC model (Predicted Environmental Concentrations in agricultural Soils) was developed and improved for the simulation of pesticide runoff. The model was applied to the Sakaecho upland bare soil field (Tokyo, Japan) to predict runoff water, sediment concentration in runoff water, pesticide concentrations in runoff water, and runoff sediment (clothianidin and imidacloprid) under artificial rainfall conditions. The results showed that the simulated time to first runoff agreed very well with the observed data.

Soil erosion and transport of Imidacloprid and Clothianidin in the upland field under simulated rainfall condition.

Surface runoff has been recognized as an important medium of pesticides transport to surface water and groundwater causing critical risk to the aquatic ecosystem. Although total pesticide transport in surface runoff in most cases reported being below 1% of applied mass, much larger losses may occur in extreme cases. In this study, surface runoff potential of Imidacloprid and Clothianidin was investigated in an upland field with 5% slope under two simulated rainfall experiments of 70 mm/h intensity.

Improvement and application of the PCPF-1@SWAT2012 model for predicting pesticide transport: a case study of the Sakura River watershed.

Background: The Soil and Water Assessment Tool combined with Pesticide Concentration in Paddy Field (PCPF-1@SWAT) model was previously developed to simulate the fate and transport of rice pesticides in watersheds. However, the current model is deficient in characterizing the rice paddy area and is incompatible with the ArcSWAT2012 program. In this study, we modified the original PCPF-1@SWAT model to develop a new PCPF-1@SWAT2012 model to address the deficiency in the rice paddy area and utilizing the ArcSWAT2012 program.

PCPF-M model for simulating the fate and transport of pesticides and their metabolites in rice paddy field.

Background: The PCPF-1 model was improved for forecasting the fate and transport of metabolites in addition to parent compounds in rice paddies. In the new PCPF-M model, metabolites are generated from the dissipation of pesticide applied in rice paddies through hydrolysis, photolysis and biological degradations. The methodology to parameterize the model was illustrated using two scenarios for which uncertainty and sensitivity analyses were also conducted.

Biomass burning in Indo-China peninsula and its impacts on regional air quality and global climate change-a review.

Although, many biomass burning (BB) emissions products (particulate matter and trace gases) are believed to be trans-boundary pollutants that originates from India and China (the two most populous countries in Asia), the information about BB emission and related contents is limited for Indo-China Peninsula (ICP) region. This motivated us to review this region pertaining to BB emission. The main objective of the review is to document the current status of BB emission in ICP region.

Development and validation of the SPEC model for simulating the fate and transport of pesticide applied to Japanese upland agricultural soil.

A pesticide fate and transport model, SPEC, was developed for assessing Soil-PEC (Predicted Environmental Concentrations in agricultural soils) for pesticide residues in upland field environments. The SPEC model was validated for predicting the water content and concentrations of atrazine and metolachlor in 5-cm deep soil. Uncertainty and sensitivity analyses were used to evaluate the robustness of the model's predictions.

Potential impacts of seasonal variation on atrazine and metolachlor persistence in andisol soil.

To estimate the potential effect of seasonal variation on the fate of herbicides in andisol soil, atrazine and metolachlor residues were investigated through the summer and winter seasons during 2013 and 2014 under field condition. The computed half-lives of atrazine and metolachlor in soil changed significantly through the two seasons of the trial. The half-lives were shorter in summer season with 16.

Simulating the fate and transport of nursery-box-applied pesticide in rice paddy fields.

Background: The Pesticide Concentration in a Paddy Field model (PCPF-1) was modified by adding a root zone compartment to simulate nursery-box-applied (NB-applied) pesticide. The PCPF-NB model was validated for predicting the concentrations of NB-applied fipronil and imidacloprid in rice paddy fields using two treatment methods: before transplanting (BT) and at sowing (AS). Uncertainty and sensitivity analyses were used to evaluate the robustness of the concentrations predicted by the model.

Export of radioactive cesium from agricultural fields under simulated rainfall in Fukushima.

In this study, we investigated the impact of rainfall on runoff, soil erosion and consequently on the discharge of radioactive cesium in agricultural fields in Fukushima prefecture using a rainfall simulator. Simulated heavy rainfalls (50 mm h(-1)) generated significant runoff and soil erosion. The average concentration of radioactive cesium (the sum of (134)Cs and (137)Cs) in the runoff sediments was ∼3500 Bq kg(-1) dry soil, more than double the concentrations measured in the field soils which should be considered in studies using the (137)Cs loss to estimate long-term soil erosion.

Effect of rice husk gasification residue application on herbicide behavior in micro paddy lysimeter.

Effects of rice husk gasification residues (RHGR) application on the fate of herbicides, butachlor and pyrazosulfuron-ethyl, in paddy water were investigated using micro paddy lysimeters (MPLs). The dissipation of both herbicides in paddy water was faster in the RHGR treated MPL than in the control MPL. The average concentrations of butachlor and pyrazosulfuron-ethyl in paddy water in the lysimeter treated with RHGR during 21 days were significantly reduced by 51% and 48%, respectively, as compared to those in the lysimeter without RHGR application.

Behavior of butachlor and pyrazosulfuron-ethyl in paddy water using micro paddy lysimeters under different temperature conditions in spring and summer.

The behavior of butachlor and pyrazosulfuron-ethyl in paddy water was investigated using micro paddy lysimeters with prescribed hydrological conditions under ambient temperature in spring and summer for simulating two rice crop seasons. Although they were not significantly different, the dissipation of both herbicides in paddy water in the summer experiment was faster than in the spring experiment. The half-lives (DT(50)) in paddy water for spring and summer experiments were 3.

Wash off of imidacloprid and fipronil from turf and concrete surfaces using simulated rainfall.

The surface runoff of imidacloprid granular product (GR) from turf surfaces, and imidacloprid emulsifiable concentrate (EC), fipronil suspension concentrate (SC) products and fipronil byproducts from concrete surfaces was investigated during 1h rainfall simulations at 50 mm/h or 25 mm/h with product incubation times of 1.5 h, 1 d, 7 d, and 14 d. About 57.

Simulating concentration of bensulphuron-methyl in a drainage canal of a paddy block using a rice pesticide model.

A pesticide fate and transport model (PCPF-B) was developed to predict the runoff of pesticides from paddy plots to a drainage canal in a paddy block based on the plot scale model (PCPF-1). The block-scale model now comprises three modules: (1) a module for pesticide application, (2) a module for pesticide behaviour in paddy fields, and (3) a module for pesticide concentration in the drainage canal. The PCPF-B model was first evaluated using published data in a single plot and then was applied to predict the concentration of bensulphuron-methyl in one paddy block in the Sakura river basin, Ibaraki, Japan, where a detailed field survey was conducted.

Photodegradation of imidacloprid and fipronil in rice-paddy water.

Photodegradation of insecticides, imidacloprid and fipronil, in rice-paddy water under the ambient temperature was investigated. The initial concentrations were set at 58.8 and 3.

Exposure risk assessment and evaluation of the best management practice for controlling pesticide runoff from paddy fields. Part 2: model simulation for the herbicide pretilachlor.

Background: Monitoring studies revealed high concentrations of pesticides in the drainage canal of paddy fields. It is important to have a way to predict these concentrations in different management scenarios as an assessment tool. A simulation model for predicting the pesticide concentration in a paddy block (PCPF-B) was evaluated and then used to assess the effect of water management practices for controlling pesticide runoff from paddy fields.

Simulating the dissipation of two herbicides using micro paddy lysimeters.

A set of packed micro paddy lysimeters, placed in a greenhouse, was used to simulate the dissipation of two herbicides, simetryn and thiobencarb, in a controlled environment. Data from a field monitoring study in 2003, including the soil condition and water balances, were used in the simulation. The herbicides were applied and monitored over a period of 21 d.

Behavior of simetryn and thiobencarb in the plough zone of rice fields.

The behavior of simetryn and thiobencarb in flooded rice soil was investigated in a 2-year study. The concentrations of simetryn and thiobencarb were in the hundreds of μg kg−1 in the top soil layer (0–5 cm) and became significantly lower in tens of μg kg−1 in the deeper soil layers (5–10 and 10–15 cm). The half-lives of the two herbicides were also shorter (36 and 17 days for simetryn and thiobencarb, respectively) in the top soil layer, as they were most affected by environmental conditions, compared with corresponding values of 82 and 69 days in the 5–10 cm soil layer.

Behavior of sprayed tricyclazole in rice paddy lysimeters.

The behavior of sprayed tricyclazole in rice paddy lysimeters was studied. Tricyclazole residues were measured from rice leaves and paddy water after tricyclazole spraying in paddy lysimeters. The rate of photolysis and hydrolysis of tricyclazole on the surface of rice leaves was also determined in a laboratory experiment.

Simulated rainfall removal of tricyclazole sprayed on rice foliage.

Two rainfall simulations of 30 mm h(-1), with 48-h interval between two simulations, were performed on rice lysimeters at 24, 48, and 72 h after being sprayed with tricyclazole. In the first simulated rainfall, wash-off concentration of tricyclazole was significant irrespective of the interval between the spray time and the rainfall simulation. And from 20.

Exposure risk assessment and evaluation of the best management practice for controlling pesticide runoff from paddy fields. Part 1: Paddy watershed monitoring.

Rice pesticide concentrations in surface water along with hydrological balance and water management conditions were investigated in a paddy watershed of about 100 ha at the Sakura river basin in Tsukuba, Japan, for 3 years from April 2002. Monitoring on different hydrological scales ranging from a paddy plot up to a watershed determined the importance of water management associated with rainfall events and the cyclic irrigation for reducing pesticide discharge into aquatic environments. Surface drainage significantly increased as a response to rainfall events greater than about 1.

Pesticide exposure assessment in rice paddies in Europe: a comparative study of existing mathematical models.

A comparative test was undertaken in order to identify the potential of existing mathematical models, including the rice water quality (RICEWQ) 1.6.4v model, the pesticide concentration in paddy field (PCPF-1) model and the surface water and groundwater (SWAGW) model, for calculating pesticide dissipation and exposure in rice paddies in Europe.