Degradation and adsorption of tralkoxydim in Chinese soils and water-sediment environments.

Tralkoxydim is a cyclohexanedione herbicide primarily used for gramineous weed control in China. In this paper, we present results of a tralkoxydim laboratory environmental fate study characterizing its degradation, adsorption, and mobility behavior in three different soils and two water-sediment systems (river and lake) in China. Degradation half-life of tralkoxydim in soil under aerobic conditions was 5.1, 7.7, and 7.9 days in Jiangxi red soil, Taihu paddy soil, and Northeast China black soil, respectively. Under anaerobic and flooding conditions, half-life values were 6.2, 15.1, and 19.8 days for the same three soils, respectively. Soil pH was the major factor effecting tralkoxydim degradation. In the aerobic water-sediment experiments, tralkoxydim degraded faster in the river system (total system half-life 43.3 days) than the lake system (total system half-life 99.0 days). Correspondingly, its anaerobic degradation half-life values were 46.2 and 53.3 days for the river and lake systems, respectively. Tralkoxydim adsorption in the three soils was found to follow the empirical Freundlich isotherm. The adsorption coefficient (K d ) was 8.60, 1.00, and 1.57 for Jiangxi red soil, Taihu paddy soil, and Northeast China black soil, respectively. Soil pH was the major factor effecting tralkoxydim adsorption. Adsorption free energy change was less than 40 kJ mol-1 in all three soils, indicating a physical mechanism in the process. Thin-layer chromatography (TLC) tests showed that relative to the solvent transport to 11.5 cm, the travel distance of tralkoxydim was 8-10 cm in the three soils, corresponding Rf values at 0.05, 0.35, and 0.75 for Jiangxi red soil, Taihu paddy soil, and Northeast China black soil, respectively. Results of this work suggest that under alkaline conditions, tralkoxydim adsorption becomes smaller; thus, assessments on its mobility and potential groundwater impact should focus on these soil types.

Desorption and mobilization of three strobilurin fungicides in three types of soil.

Phenamacril (JS399-19 with independent intellectual property developed by China), azoxystrobin, and kresoxim-methyl are strobilurin fungicide. Due to their broad spectrum and good control of most of known fungi, strobilurin fungicide has been widely used in agriculture management. Thus, it is important to evaluate their environmental behaviors particularly in soils and underground water. In this study, the sorption/desorption and mobility of strobilurin fungicides in three Chinese soils (Jiangxi red soil, Taihu paddy soil, and Northeast China black soil) were conducted using comprehensively analytic approaches including batch experiment and soil thin-layer chromatography. The strobilurin fungicides were hard to be adsorbed in Jiangxi red soil but had medium adsorption capability in Tanhu paddy soil and Northeast China black soil, while the desorption of three strobilurin fungicides ranked in the order of Jiangxi red soil > Taihu paddy soil > Northeast China black soil. Soil properties including soil organic matter (SOM), pH, and cationic exchange capacity (CEC) affected the adsorption/desorption of the fungicides. Azoxystrobin and kresoxim-methyl had weak mobility in the soils. JS399-19 was moderately mobile in Jiangxi red soil but was not easily moved in Taihu paddy soil and Northeast China black soil. Due to their weak mobility in soils, these strobilurin fungicides tended to remain in the soil phase but not to shift downward to underground water. As azoxystrobin and JS399-19 had a long retention period in soil, there may become persistent residues in the soil environment.

[Residue dynamics of flubendiamide in paddy field].

Residue dynamics and terminal residue of flubendiamide 19.8% suspension concentrate (SC) in rice and field environment were measured by ultra performance liquid chromatography (UPLC). As flubendiamide and its metabolite were applied at a range of concentrations from 0.05 to 1.0 mg.kg-1, average recoveries of them in soil, water, rice straw, rice grain and rice hull samples ranged from 78.2% to 104.8%, with variation coefficients of 1.1% -4.4%. One-year and three-area results showed that the half-life of gradation for flubendiamide was 9. 8 to 17.3 d in water, 10. 8 to 22.4 d in soil, and 7.6 to 17.3 d in rice plants, respectively. Residues of metabolite NNI-des-iodo in water were detected, but not in soil or rice plants. When flubendiamide was applied at the recommended dose, its residue in rice grain on the 10th day after application was lower than 0.5 mg.kg-1, the maximum residue limit allowed by US for agricultural chemical residues in rice.

The third heart sound after exercise in athletes: an exploratory study.

The purpose of our study was to investigate the frequency of the third heart sound (S3) of athletes after exercise, and to determine whether the frequency and amplitude of S3 were related to cardiac function. The phonocardiogram exercise test (PCGET) was used in this study, and healthy volunteers consisting of 84 athletes (age 21.0±1.7 years; 62 males and 22 females) and 45 non-athletes (age 24.1±2.0 years; 33 males and 12 females) were enrolled. All subjects were healthy except one with a cardiac murmur without known cause. Immediately after exercise, S3 occurred in 21 athletes (25.0%) and 10 non-athletes (22.2%) during PCGET. There were very significant differences between pre-exercise and post-exercise in the frequency of S3 (P<0.01), and no significant difference between athletes and nonathletes (P>0.05). The prevalence of S3/S2≥1 was significantly (P<0.05) higher for the athlete group (47.1%) as compared to the non-athlete group (10%). Those results indicated that the emergence of S3 was an indicator of heart burden, and S3 after exercise in the athlete group was physiological. Our study showed that the amplitude of S3 had a very sensitive response to cardiac function reduction and S3/S2≥1 could eventually be used to assess cardiac fatigue states.

[Research on a new method and index for evaluating cardiac function of the athletes].

OBJECTIVE: To explore the new indexes and new methods for the noninvasive measuring and evaluating cardiac function detection of the athletes. METHODS: Heart sound signals were sampled randomly from 81 students in physical education department (experiment group) and 41 students in general departments (control group) after completing designed workload during step-climbing exercise, the contrast study on heart rate, D/S ratio as well as the S1/S2 ratio of students from physical education and general department has been conducted. RESULTS: In the resting state, the physical education department students' heart rate and D/S ratio was 66 +/- 8.7 and 2.04 +/- 0.33 respectively; general department students' heart rate and D/S ratio was 71 +/- 8.0 and 1.82 +/- 0.27 respectively. In the whole exercise, the physical education department students S1/S2 ratio was 7.34 +/- 4.04; general department students S1/S2 ratio was 5.22 +/- 2.38. CONCLUSION: Students from physical education department have higher level of cardiac reserve than that of students from general department. The method can evaluate cardiac reserve for athletes and general persons, and provide a new quantity evaluation index for selecting athletes and evaluating cardiac function of general persons.

[Effect of dissolved organic matter on phenanthrene sorption-desorption in soil system].

Batch experiments were conducted to investigate effect of dissolved organic matter (DOM) on the adsorption and desorption behavior of Phenanthrene (Phe) in a soil-water system. It was found that three natural DOM derived from pig manure (PM), sewage sludge (SS), green manure (GM) and a kind of surfactant Tween-80 can reduced sorption of Phenanthrene significantly onto the tested soil. Within the selected concentration of the Phenanthrene and DOM in this study, the sorption quantity has a negative-linear correlativity with the concentration of DOM (r(PM) = - 0.988 8, r(SS) = - 0.982 6, r(Tween-80 = - 0.974 3, r(GM) = - 0.990 5). The inhibition of Phenanthrene sorption caused by DOM of PM origin was more significant than that of SS origin and GM origin for the same soil. Phenanthrene sorption isotherm could be described well by the Freundlich equation. It implied that DOM can affect the environmental behaviors of Phenanthrene in soil.