[Moderate grazing increases the abundance of soil methane-oxidizing bacteria and CH4 uptake rate in a typical steppe of Inner Mongolia, China.] / é€‚åº¦æ”¾ç‰§å¢žåŠ å† è’™å¤å ¸åž‹è‰åŽŸç”²çƒ·æ°§åŒ–èŒä¸°åº¦å’Œç”²çƒ·å¸æ”¶.

Microbial oxidation is the only biological sink of atmospheric methane (CH4). It is essential to understand the variation of CH4 fluxes among different grassland use types for developing low-emission management system. Here, we measured the CH4 flux and the soil methane-oxidizing bacteria abundance in a typical steppe under grazing, mowing and fencing management in central Inner Mongolia, with the aims to determine the effects of these grassland use types on CH4 flux, and to test the hypothesis that pmoA functional gene abundance regulates CH4 fluxes. The measurements were conducted on the experimental grassland that had experienced four grassland use treatments over five years. The treatments were whole growing season grazing from May to September (T1), spring and summer grazing (twice in May and July)(T2), autumn mowing (T3) and enclosure (T0). We measured CH4 flux using static chamber method, and quantified the abundance of pmoA functional genes using molecular techniques. Moreover, we measured plant biomass and soil physicochemical properties. The results showed that moderate grazing significantly enhanced CH4 uptake rate and the methane-oxidizing bacteria abundance (i.e., the pmoA gene copy number per gram of dry soil). The pmoA gene copy number ranged from 6.9×104 to 3.9×105 per gram of dry soil in growing season. The CH4 uptake rate was (68.21±3.01) µg·m-2·h-1 under T1, which was 22.1%, 37.5% and 30.9% higher than that under T2, T3 or T0 , respectively. The CH4 uptake rate was positively correlated with abundance of CH4 oxidizing bacteria and soil sand content, but negatively correlated with soil silt content, soil moisture, NH4+-N and NO3--N content, and plant biomass. These results suggested that the steppe ecosystem is a CH4 sink under all land-use types in central Inner Mongolia, and that moderate grazing would enhance methane-oxidizing bacteria abundance and CH4 uptake by improving soil sand content, reducing soil mineral nitrogen content and plant production in the typical steppe ecosystem. These results were of significance for the development of low-emission grassland management system.

[Determination of aconitine, hypaconitine and mesaconitine in Shenfu injection].

To establish a method for the content determination of indexes for measuring aconitic compounds contained in Shenfu injection, in order to provide basis for the evaluation of the curative effect of monkshood in Shenfu injection. The sample were purified and enriched with HF-LPME. ACQUITY UPLC BEH C18 column (2.1 mm x 50 mm, 1.7 microm) was adopted and eluted with a gradient program, with acetonitrile-10 mmol x L(-1) NH4HCO3 (pH 10) as the mobile phases. The flow rate was 0.45 mL x min(-1). The content was determined with ESI and MRM. The results showed that aconitine, hypaconitine and mesaconitine showed a good linear relationship, with r > 0.999, within the range of 0.1-100 ng x L(-1). The recoveries were detected to be 100.1%, 97.4%, 97.5%, with RSD being 1.2%, 1.1%, 1.5%, respectively. This method was used to prove the safety of Shenfu injection, and provide scientific basis for correct evaluation of curative effect of monkshood, as well as a reliable, simple and practical means for quality control of monkshood-containing Chinese materia medica preparations.

Research and control of well water pollution in high esophageal cancer areas.

AIM: In order to detect risk factors for esophageal cancer, a national research program was carried out during the Eighth Five-Year Plan (from 1991 to 1995). METHODS: Cixian County and Chichen County in Hebei Province were selected as the index and the control for the study fields with higher or lower incidence of esophagus cancer in China, respectively. In these areas, we investigated the pollution of three nitrogenous compounds in well water for drinking and the use of nitrogen fertilizer in farming. RESULTS: In well water, nitrate nitrogen, nitrite nitrogen and ammonia nitrogen were 8.77 mg/L, 0.014 mg/L and 0.009 mg/L in Cixian County in 1993, respectively. They were significantly higher than their levels (3.84 mg/L, 0.004 mg/L and 0.004 mg/L) in Chichen County (P<0.01, t=6.281, t=3.784, t=3.775). There was a trend that the nitrogenous compounds in well water increased from 1993 to 1996. The amount of nitrogen fertilizer used in farming was 787.6 kg per hectare land in Cixian County in 1991, significantly higher than 186 kg per hectare in Chichen County (t=9.603, P<0.001). CONCLUSION: These investigations indicate that the pollution of nitrogenous compounds in well water for drinking is closely related to the use of nitrogen fertilizer in farming, and there is a significantly positive correlation between the level of three nitrogenous compounds in well water and the mortality of esophageal cancer (correlation coefficient =0.5992). We suggest that improvement of well system for drinking water quality should be an effective measure for esophageal cancer prevention and control in rural areas.