Landscape risk analysis for pesticides applied to rice paddies

Abstract

The use of geographical information system (GIS) datasets in combination with mathematical modeling has been proven a powerful tool for modeling refinement at higher tier assessment in all crop situations. This study constitutes the first attempt to predict pesticide exposure in surface-water and groundwater systems of a rice watershed using a combination of GIS and modeling. A rice-cultivated watershed in the region of Lombardy, province of Pavia, Italy was selected. The community of Tromello is bypassed by the river Terdoppio, which along with drainage canals and streams creates a rice watershed of 467 ha, comprising 201 paddies. The watershed was conceptualized using a combination of the rice water quality (RICEWQ 1.6.4v) and river water quality (RIVWQ 2.02) models. Spatial GIS data (land use, soil properties and hydrology), on-site scouting and personal interviews with the farmers were used for modeling parameterization. Application of RICEWQ in each of the paddies provided groundwater predicted environmental concentrations for the herbicides propanil and molinate. Groundwater predicted concentrations did not exceed 0.1 µg/L in any of the propanil-treated paddies, unlike molinate, whose predicted concentrations exceeded 0.1 µg/L in 7 of the 31 molinate-treated paddies. Pesticide mass and water releases from paddies were used as inputs for canals, streams and the river, and the fate of propanil and molinate was simulated with RIVWQ. Comparison of the predicted concentrations of molinate and propanil for the year 1999 at the most downstream point of the simulated segment of the river Terdoppio, with measured values obtained from approximately the same point of the river showed a relatively good agreement. These results indicate that the combination of GIS with validated models can be a useful option for higher tier exposure assessment and modeling refinement in rice-paddy areas.

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

“…The Sakura River watershed located in Ibaraki Prefecture, Japan has a total catchment area of about 335 km 2 . The mainstream of the watershed is the Sakura River, which flows into Lake Kasumigaura.…”

“…The Sakura River watershed located in Ibaraki Prefecture, Japan has a total catchment area of about 335 km 2 . 22,29 The mainstream of the watershed is the Sakura River, which flows into Lake Kasumigaura. The topography of the watershed is classified as mountainous in the north, and flat in the west and southeast of the watershed, with average elevation ranging from 9 to 852 m ( Fig.…”

“…For block‐scale applications, the PCPF‐B can be used . At the watershed scale, simulation of the fate and transport of rice pesticide can be performed by (i) the River Water Quality (RIVWQ) integrated with RICEWQ (RICEWQ‐RIVWQ), (ii) the PADDY‐Large, (iii) the Soil and Water Assessment Tool (SWAT) combined with PCPF‐1 (PCPF‐1@SWAT), and (iv) the Dynamic in‐River Agrochemical Fate and Transport (DRAFT) coupled with PCPF‐1 for paddy block scale (PCPF‐B) and the land use based tank (PCPF‐B/DRAFT) models . The potential environmental risks posed by rice pesticide in a watershed can be evaluated using the last four models.…”

“…21 At the watershed scale, simulation of the fate and transport of rice pesticide can be performed by (i) the River Water Quality (RIVWQ) integrated with RICEWQ (RICEWQ-RIVWQ), (ii) the PADDY-Large, (iii) the Soil and Water Assessment Tool (SWAT) combined with PCPF-1 (PCPF-1@SWAT), and (iv) the Dynamic in-River Agrochemical Fate and Transport (DRAFT) coupled with PCPF-1 for paddy block scale (PCPF-B) and the land use based tank (PCPF-B/DRAFT) models. [22][23][24][25] The potential environmental risks posed by rice pesticide in a watershed can be evaluated using the last four models. However, both the RICEWQ-RIVWQ and PADDY-Large algorithms focus on simulating paddy hydrology and ignore other types of land use, which may significantly contribute to the watershed hydrology and thus affect the accuracy of the predicted pesticide concentrations in the watershed.…”

Opinion of the Scientific Panel on Plant protection products and their residues (PPR) related to the revision of Annexes II and III to Council Directive 91/414/EEC concerning the placing of plant protection products on the market - Fate and Behaviour in t

“…Since 2000, a series of models have been published to generate exposure estimates in aquatic and soil environments for pesticides that are used in rice cultivation at step 2 (Karpouzas et al, 2006a) and for refinement of assessment at step 3 (Karpouzas et al, 2006b). The results of studies performed in the past with different pesticides in rice can be used to check the validity and consistency of this approach, as recommended by SCP (2003).…”