Off‐Field Movement and Dissipation of Soil‐Incorporated Carbofuran from Three Commercial Rice Fields

Abstract

Residues of curbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate) were detected in agricultural drain water collected in the Sacramento Valley, a major rice (Oryza sativa L.) growing region of California. Runoff water from rice fields was suspected as the major source for these residues. In response to this problem we measured soil‐incorporated carbofuran; (i) discharged in runoff, (ii) dissipated from paddy soil and water, and (iii) recovered in paddy soil vs. paddy water over time. This work was conducted in three commercial rice fields in Colusa and Glenn Counties in California. A total of 1.72, 5.40 and 11.03% of carbofuran mass applied was discharged in runoff water from Fields 1, 2, and 3, respectively, during a 54‐ to 80‐d period after flooding. Downstream concentrations, up to 4.4 µg L−1, indicated the need for reduced carbofuran discharges to meet a 1991 regional standard of 0.4 µg L−1. Most of the carbofuran lost in runoff was discharged during the first 30‐d period after initial flooding in Field 2, and during the 31‐ to 60‐d period in Fields 1 and 3. Dissipation of carbofuran mass, measured separately in rice paddy soft and rice paddy water, was a log‐linear function of time in both media. An exception occurred in paddy soil of Field 3 where carbofuran mass did not decline significantly over a 70‐d sampling period. Soil half‐lives were 58 and 43 d after flooding for Fields 1 and 2, respectively. Water half‐lives for Fields 1, 2, and 3 were 22, 26, and 18 d, respectively. Most of the carbofuran mass applied to the fields remained in paddy soil and, on average, no more than 27% of the applied mass was found in paddy water on any single day during the study. Soil‐incorporation may reduce the amount of carbofuran released into paddy water, and subsequently moved off‐field in runoff.

Characterization of a novel carbofuran degradingPseudomonassp. with collateral biocontrol and plant growth promoting potential

“…The oral LD 50 value of carbofuran in mice and other animals has been reported to vary from 2 to 9 mg kg −1 body weight [2,3]. In the environment, such pesticides with high water solubility and lower adsorption coefficient [4] leach through the unsaturated soil zones and cause contamination of lakes, streams and groundwater [5]. Indeed, agricultural soil serves as an ultimate sink for agrochemicals, where soil microflora involved in bioremediation contribute in reducing pollution load.…”

Photodecomposition of the Carbamate Pesticide Carbofuran: Kinetics and the Influence of Dissolved Organic Matter

“…Specifically, the carbamate pesticide carbofuran has been found in surface water that serves as a drinking water source for Sacramento, CA (). Given the potential human and wildlife health risks associated with toxic pesticides in surface waters ( , ), it is important to determine the probability that a certain chemical will persist in the environment by examining the various reactions of the molecule. Transformations such as microbial, chemical, and photochemical degradation are recognized as the significant processes in determining the fate and transport of pesticides.…”

Degradation and Persistence of Carbofuran in Peanut and Soil in Field Trails as Determined by GC-MS

“…The mechanism may be related with the difference of the soil properties and climatic temperature in the two field sites. Among the factors affecting the degradation of carbofuran in soil-plant systems, the pH value, organic matter content, soil texture as well as the local temperature play an important role in degradation of carbofuran [15,19,20,21] , the higher pH value (7.73), lower organic matter (1.31%) and clay content (22.4) in soil for Jinan site than those in Langfang may result in faster degradation. Moreover, the higher annual average climatic temperature in Jinan (14.0°C) than that in Langfang (11.9°C) might have been one of influence factors for the result.…”