Radio Detection of the Sun

The radio emission of the Sun has been measured using a radio interferometer including two Yagi antennas operated at 610 MHz. We report the observation of interferences and comment on the results

Prediction of the fate of oxytetracycline and oxolinic acid in a fish pond using simulation model: A preliminary study

The fate of two popular antibiotics, oxytetracycline and oxolinic acid, in a fish pond were simulated using a computational model. The VDC model, which is designed based on a model for predicting pesticide fate and transport in paddy fields, was modified to take into account the differences between the pond and the paddies as well as those between the fish and the rice plant behaviors. The pond conditions were set following the typical practice in South East Asia aquaculture. The two antibiotics were administered to the animal in the pond through medicated feed during a period of 5 days as in actual practice. Concentrations of oxytetracycline in pond water were higher than those of oxolinic acid at the beginning of the simulation. Dissipation rate of oxytetracycline is also higher as it is more readily available for degradation in the water. For the long term, oxolinic acid was present at higher concentration than oxytetracycline in pond water as well as pond sediment. The simulated results were expected to be conservative and can be useful for the lower tier assessment of exposure risk of veterinary medicine in aquaculture industry but more data are needed for the complete validation of the model

Behavior of nursery-box-applied imidacloprid in micro paddy lysimeter

A micro paddy lysimeter (MPL) was employed to monitor the behavior of nursery-box-applied imidacloprid granules in the rice paddy environment using two treatment methods, i.e. before transplanting (BT) and at sowing (AS). Tested application rates were three-fold the recommended rate. Under a water management scenario in an actual field, the behavior of nursery-box-applied imidacloprid granules in paddy water and paddy soil in MPL was comparable with field monitoring data in the literature. Imidacloprid concentration in water peaked at 189±36 μg/L and 13.1±1.4 μg/L at 1 day after transplanting (DAT), and the halflives (DT) were 2.5 days, and 4.7 days for BT and AS treatments, respectively. In the soil profile, the maximum concentration of imidacloprid at 21 DAT was 65.6±0.4 μg/kg and 39.7±4.9 μg/kg in the 0-2.5 cm layer in the inter-row zone for BT and AS treatments, respectively. Imidacloprid was found in the 12.5-15.0 cm layer at 3.2±0.7 μg/kg for BT treatment and 13.7±3.8 μg/kg for AS treatment, in the inter-row zone. In AS treatment, imidacloprid mainly stayed in the root zone (0-5 cm surface soil layer), and its concentration was 895±4 μg/kg at 21 DAT. MPL presented as a convenient and alternative tool to monitor the behavior of nursery-box-applied pesticide in the rice paddy environment

Prediction of the fate of oxytetracycline and oxolinic acid in a fish pond using simulation model - a preliminary study

The fate of two popular antibiotics, oxytetracycline and oxolinic acid, in a fish pond were simulated using a computational model. The VDC model, which is designed based on a model for predicting pesticide fate and transport in paddy fields, was modified to take into account the differences between the pond and the paddies as well as those between the fish and the rice plant behaviors. The pond conditions were set following the typical practice in South East Asia aquaculture. The two antibiotics were administered to the animal in the pond through medicated feed during a period of 5 days as in actual practice. Concentrations of oxytetracycline in pond water were higher than those of oxolinic acid at the beginning of the simulation. Dissipation rate of oxytetracycline is also higher as it is more readily available for degradation in the water. For the long term, oxolinic acid was present at higher concentration than oxytetracycline in pond water as well as pond sediment. The simulated results were expected to be conservative and can be useful for the lower tier assessment of exposure risk of veterinary medicine in aquaculture industry but more data are needed for the complete validation of the model

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. The water balances under two water management scenarios, intermittent irrigation management (AI) and continuous irrigation management (CI), were simulated. In the AI scenario, the pattern of herbicide dissipation in the surface water of the field were simulated, following the first-order kinetics. In the CI scenario, similarity was observed in most lysimeter and field concentrations, but there were differences in some data points. Dissipation curves of both herbicides in the surface water of the two simulated scenarios were not significantly different (P > 0.05) from the field data except for intercept of the thiobencarb curve in the CI scenario. The distribution of simetryn and thiobencarb in the soil profile after simulation were also similar to the field data. The highest concentrations of both herbicides were found on the topsoil layer at 0-2.5 cm depth. Only a small amount of herbicides moved down to the deeper soil layers. Micro paddy lysimeters are thus a good alternative for the dissipation study of pesticides in the paddy environment

Changes in lycopene and beta carotene contents in aril and oil of gac fruit during storage

Gac fruits were physically measured and stored under ambient conditions for up to 2 weeks to observe changes in carotenoid contents (lycopene and beta carotene) in its aril. Initial concentrations in the aril of lycopene were from 2.378 mg/g fresh weight (FW) to 3.728 mg/g FW and those of beta carotene were from 0.257 to 0.379 mg/g FW. Carotenoid concentrations in the aril remained stable after 1 week but sharply declined after 2 weeks of storage. Gac oil, pressed from gac aril, has similar concentrations of lycopene and beta carotene (2.436 and 2.592 mg/g, respectively). Oil was treated with 0.02% of butylated hydroxytoluene, or with a stream of nitrogen or untreated then stored in the dark for up to 15 or 19 weeks under different temperatures (5 °C, ambient, 45 and 60 °C). Lycopene and beta carotene in control gac oil degraded following the first-order kinetic model. The degradation rate of lycopene and beta carotene in the treated oil samples were lower than that in the control oil but the first-order kinetic was not always followed. However, both lycopene and beta carotene degraded quickly in gac oil with the first-order kinetic under high temperature conditions (45 and 60 °C) regardless of the treatments used

Temporal trend of pesticide concentrations in the Chikugo River (Japan) with changes in environmental regulation and field infrastructure

Contamination of pesticides, which are applied to rice paddy fields, in river water has been a major problem in Japan for decades. A prolonged water holding period after pesticide application in paddy fields is expected to reduce the concentration of rice pesticides in river water. Therefore, a long monitoring campaign was conducted from 2004 to 2010 to measure the concentrations of pesticides in water samples collected from several points along the Chikugo River (Japan) including tributaries and the main stream to see if there was any reduction in the level of pesticide contamination after the extension of the water holding period (from 3–4 days to 7 days) was introduced in 2007 by the new water management regulation. No significant difference (p > 0.05) was found in pesticide concentrations between the periods before and after 2007 in all monitoring points, except in one tributary where the pesticide concentrations after 2007 were even higher than that of the previous period. A detailed study in one of the tributaries also revealed that the renovated infrastructure did not reduce the pesticide concentrations in the drainage canals. Neither the introduction of the new regulation nor the improved infrastructure had any significant effect on reducing the contamination of pesticides in water of the Chikugo River. It is probably because most farmers did not properly implement the new requirement of holding paddy water within the field for 7 days after the application of pesticides. Only tightening the regulation would not be sufficient and more actions should be taken to enforce/provide extension support for the new water management regulation in order to reduce the level of residual pesticides in river water in Japan

PHÂN LẬP CÁC CHỦNG VI KHUẨN HIẾU KHÍ CÓ KHẢ NĂNG PHÂN HỦY CHLORPYRIFOS TRONG ĐẤT TRỒNG RAU MÀU Ở TỈNH LÂM ĐỒNG

This study aims to isolate aerobic bacteria strains for decomposing chlorpyrifos in soil in Lam Dong.  The number of microorganisms for decomposing chlorpyrifos can be increased by incubating the soil samples in MSM medium supplemented with chlorpyrifos (20 mg/L) as the only carbon source. Three aerobic bacteria strains were isolated after the separating each bacterial strain and investigating the decomposition ability chlorpyrifos processing, which were further named as T1, W3 and B2, respectively.  In particular, T1, W3 and B2 strains removed 50.4%, 59.3% and 62.2% of chlorpyrifos after 14 days of culture in MSM medium in supplementation with 20 mg/L chlorpyrifos, respectively. Acinetobacter calcoaceticus, Bacillus megaterium and Sphingomonas pseudosanguinis were identified by 16S rRNA gene sequencing. The three strains of bacteria exhibit ability to degrade chlorpyrifos when added to the soil environment. These results suggested that the isolated bacteria strains can be applied to treat contaminated soil with pesticides and irritate the plant growing.Nghiên cứu này được thực hiện với mục đích phân lập được các chủng vi khuẩn hiếu khí có khả năng phân hủy dư lượng thuốc bảo vệ thực vật chlorpyrifos tồn dư trong đất tại Lâm Đồng. Tiến hành làm giàu dòng vi khuẩn hiếu khí bản địa tại Lâm Đồng có khả năng phân hủy chlorpyrifos bằng cách ủ dịch chiết các mẫu đất trong môi trường MSM bổ sung chlorpyrifos đạt nồng độ 20 mg/L làm nguồn cacbon duy nhất. Tách riêng từng dòng vi khuẩn và khảo sát khả năng phân hủy chlorpyrifos đã chọn ra được 3 dòng vi khuẩn hiếu khí kí hiệu là T1, W3 và B2. Kết quả thí nghiệm cho thấy cả 3 dòng này đều có khả năng phân hủy chlorpyrifos, lần lượt là 50,4%, 59,3% và 62,2% hàm lượng chlorpyrifos sau 14 ngày nuôi cấy trong môi trường MSM bổ sung 20 mg/L chlorpyrifos. Ba dòng vi khuẩn được định danh lần lượt là Acinetobacter calcoaceticus, Bacillus megaterium và Sphingomonas pseudosanguinis bằng phương pháp giải trình tự gen 16S rRNA. Cả ba dòng vi khuẩn này đều thể hiện khả năng phân hủy chlorpyrifos tốt khi bổ sung vào môi trường đất, từ đó cho thấy chúng có tiềm năng ứng dụng cao để sản xuất tạo ra các chế phẩm vi sinh giúp xử lý đất ô nhiễm