Contamination of rice field water with sulfonylurea and phenoxy herbicides in the Muda Irrigation Scheme, Kedah, Malaysia

Abstract

The purpose of the present study was to investigate the potential risk of herbicide contamination (2,4-dichlorophenoxy (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA), metsulfuron, bensulfuron, and pyrazosulfuron) in the rice fields of the Muda Irrigation Scheme, Kedah, Malaysia. The study included two areas with different irrigation water sources namely non-recycled (N-RCL) and recycled (RCL) water. Periodic water sampling was carried out from the drainage canals during the planting period of the wet season 2006/2007 and dry season 2007. The HPLC-UV was used to detect herbicide residues in the water samples collected from the rice fields. The results showed that the concentration of sulfonylurea herbicides such as bensulfuron and metsulfuron in the rice field was 0.55 and 0.51 μg/L, respectively. The potential risk of contamination depended on the actual dosage of each herbicide applied by farmers to their rice fields. The potential risk of water pollution by the five herbicides studied in the area with RCL water tended to be more widespread compared to the area with N-RCL water due to surface water runoff with higher levels of weedicides to the surrounding areas. During the two seasons, 50-73% of the water samples collected from the area receiving RCL water contained the five herbicides studied at concentrations of more than 0.05 μg/L, and this percentage was higher than that from the areas receiving N-RCL water (45-69%). During the wet season, the overall total mean concentration of the eight herbicides found in the samples collected from the area with RCL water (6.27 μg/L) was significantly higher (P < 0.01) than that from the area receiving N-RCL water (2.39 μg/L). Meanwhile, during the dry season, there was no significant difference (P > 0.05) in the herbicide concentrations between the areas receiving RCL (6.16 μg/L) and N-RCL water (7.43 μg/L) water.

Triclopyr 3, 5, 6-Trichloro-2-Pyridinyl Clean-Up Procedure from Soil, Sediment and Water Samples using SPE-HPLC-VWD

“…The adsorbent eluents are usually organic solvents containing appropriate concentrations of buffer solution or aqueous solution for the reverse phase column. The adsorbent eluents for anion-exchange are usually ionic compounds (Ismail et al 2015d). In the experiment, Cromabond PS-H + /OH -was washed with 3 mL AcOH/water (5:95, v/v) for the removal of impurities.…”

Dissipation of Chlorpyrifos in a Malaysian Agricultural Soil: A Comparison between a Field Experiment and Simulation by the VARLEACH and PERSIST Models

“…Previous studies have demonstrated that FIGURE 1. GC-XSD Chromatograms of (a) Chlorpyrifos standard solution, 0.02 μg/mL, (b) Untreated sample of soil and (c) Spike soil sample containing 0.02 μg/g of chloropyrifos several factors, such as adsorption of the pesticide to soil particles, water solubility of the pesticide, volume of leachate, pH and soil texture, can influence the leaching of the pesticides through the soil (Ismail et al 2015d;Nicholls et al 1982). Other factors such as volatilization, runoff, leaching, chemical and biological degradation, absorption and photolysis could enhance the degradation rate especially under the Malaysian weather conditions.…”

Untitled

“…Temperature has a significant effect on adsorption by soils through its effect on solubility, and this adsorption has been shown for parathion by Behrendt et al (1990) as well as for atrazine (Dinehart et al 2009;Ismail et al 2015d). Druart et al (2011) explored the dissimilarity in the adsorption mechanisms of the protonated and ionized forms of pentachlorophenol (PCP) by standardizing their adsorption coefficients at three different temperatures (4°C, 25°C and 55°C).…”