Fate of the 14 C-labeled herbicide prosulfocarb in a soil and in a sediment-water system

• Published in: Journal of environmental science and health. Part B, Pesticides, food contaminants, and agricultural wastes Pesticides, food contaminants, and agricultural wastes, 2017-02, Vol.52 (2), p.122-130
• Main Authors: Braun, Karsten E, Luks, Ann-Katrin, Schmidt, Burkhard
• Format: Article
• Language: English
• Subjects: Adsorption; Agriculture; Benzopyrans - chemistry; Carbamates - chemistry; Carbon Dioxide - chemistry; Carbon Radioisotopes - chemistry; China; Geologic Sediments - chemistry; Herbicides - chemistry; Humic Substances; Pesticide Residues - chemistry; Soil - chemistry; Soil Pollutants - chemistry; Sulfoxides - chemistry; Thiocarbamates - chemistry; Volatilization; Water - chemistry; Water Pollutants, Chemical - chemistry
• ISSN: 0360-1234; 1532-4109
• DOI: 10.1080/03601234.2016.1248140

The fate of C-labeled herbicide prosulfocarb was studied in an agricultural soil and in a sediment-water system, the sediment part of which was derived from Yangtze Three Gorges Reservoir, China. Time-course studies were performed for 28 d and 49 d, respectively. Main transformation routes of C-prosulfocarb were mineralization to CO and formation of nonextractable residues amounting to 12.13% and 10.43%, respectively, after 28 days (soil), and 9.40% and 11.98%, respectively, after 49 d (sediment-water system). Traces of prosulfocarbsulfoxide were detected by means of TLC, HPLC, and LC-MS; other transformation products were not found. Initial extraction of soil assays using 0.01 M CaCl solution showed that the bioavailability of the herbicide was considerably low; immediately after application (0.1 d of incubation), only 4.78% of applied radioactivity were detected in this aqueous fraction. DT values of C-prosulfocarb estimated from radio-TLC and -HPLC analyses were above 28 d in soil and ranged between 29 d and 49 d in the sediment-water system. Partitioning of C from water to sediment phase occurred with DT slightly above 2 d. With regard to the sediment-water system, adsorption occurred with log K = 1.38 (calculated from 2 day assays) and 2.35 (49 d assays). As similarly estimated from portions of C found in CaCl extracts of the 0.1 d assays, C-prosulfocarb's log K in soil was 2.96. With both experiments, similar portions of nonextractable radioactivity were associated with all soil organic matter fractions, i.e. nonhumics, fulvic acids, humic acids, and humin/minerals. Throughout all sample preparation, the experiments were severely impaired by losses of radioactivity especially with concentration of samples containing water in vacuo. All findings pointed to volatility of parent prosulfocarb in presence of water rather than volatility of transformation products. According to literature data, this behavior of prosulfocarb was not expected, though volatility was demonstrated under field conditions.