The stable isotope signature of methane emitted from plant material under UV irradiation

Recent experiments have shown that dry and fresh leaves, other plant matter, as well as several structural plant components, emit methane upon irradiation with UV light. Here we present the source isotope signatures of the methane emitted from a range of dry natural plant leaves and structural compounds. UV-induced methane from organic matter is strongly depleted in both ¹³C and D compared to the bulk biomass. The isotopic content of plant methoxyl groups, which have been identified as important precursors of aerobic methane formation in plants, falls roughly halfway between the bulk and CH₄ isotopic composition. C3 and C4/CAM plants show the well-established isotope difference in bulk ¹³C content. Our results show that they also emit CH₄ with different δ¹³C value. Furthermore, δ¹³C of methoxyl groups in the plant material, and ester methoxyl groups only, show a similar difference between C3 and C4/CAM plants. The correlation between the δ¹³C of emitted CH₄ and methoxyl groups implies that methoxyl groups are not the only source substrate of CH₄.Interestingly, δD values of the emitted CH₄ are also found to be different for C3 and C4 plants, although there is no significant difference in the bulk material. Bulk δD analyses may be compromised by a large reservoir of exchangeable hydrogen, but no significant δD difference is found either for the methoxyl groups, which do not contain exchangeable hydrogen. The δD difference in CH₄ between C3 and C4 plants indicates that at least two different reservoirs are involved in CH₄ emission. One of them is the OCH₃ group, the other one must be significantly depleted, and contribute more to the emissions of C3 plants compared to C4 plants. In qualitative agreement with this hypothesis, CH₄ emission rates are higher for C3 plants than for C4 plants.     

增补UV-B辐射下南亚热带森林建群树种叶片对UV-B辐射的防护

研究了我国南亚热带森林5种建群树种UV-B辐射诱导的UV-B吸收物质(在280～320 nm波长下测定)的积累及抗UV-B辐射的可能性保护机制.增补UV-B辐射下,马尾松(Pinus massoniana)针叶的甲醇可溶性提取物和细胞壁的碱提取酚类的含量明显高于正常水平的光辐射下.红椎(Castanopsis hystrix)和厚壳桂(Cryptocarya chinensis)叶片的这些化学物质也升高,意味着增补UV-B辐射刺激UV-B辐射吸收物质的生成,形成抗UV-B辐射的功能性保护结构.然而,自然光下已含有大量细胞壁碱提取酚类的荷木(Schima superba)和藜蒴(Castanopsis fissa),这些化合物在增补UV-B辐射下则见下降,很有可能表皮层细胞壁碱提取酚类被转移到含有较低甲醇可溶性色素的液胞可溶性化合物里,这一现象意示着可能涉及叶肉组织光合机构的保护策略.增补UV-B下,马尾松针叶的叶绿素a和b含量不受影响,而其他4种阔叶树叶片则下降10.7% 到16.8%不等.胡萝卜素对增补UV-B辐射的响应变化不一,红椎和荷木的胡萝卜素水平下降,而马尾松、厚壳桂和藜蒴的胡萝卜素则上升,后者也许与功能性增加激发能耗散有关.结果显示,自然条件下不同树种展示出不同的驯化策略以形成抗UV-B辐射增加的防护机制.表4参29     

山东潍坊紫外线辐射特征及影响因素

近10多年来,随着人类居住环境的恶化,紫外线给人类造成了巨大的伤害。利用潍坊市气象台2004~2006年逐日紫外线观测资料,分析了太阳紫外线辐射到达地面的强度指数和等级,同时分析了这些量的年、月、日变化特征,研究了影响紫外线辐射的主要的几种因子。影响紫外线辐射强度的主要因素是臭氧、地表反射率、大气气溶胶和云,这些影响因素的变化对太阳紫外线到达地面的辐射起着举足轻重的作用。     

内蒙古包头放射性废物库安全运行25年

文章简要论述了内蒙古包头放射性废物库现状、扩建工程及环境整治工程概况,通过对库区、库外辐射环境质量监测,放射性处于一般环境水平,废物库运行20多年来,未对周围环境造成污染,通过整治工程的建设,达到了预期治理要求,废物库运行是安全的。     

铁屑吸附-微波辐照-内电解协同处理结晶紫染料废水

以结晶紫为模型化合物,提出了一种新的“铁屑吸附—微波辐照—内电解”协同处理染料废水的方法。试验结果表明,吸附在铁屑表面的染料通过微波催化裂解和内电解协同作用迅速降解,染料溶液的脱色率和COD去除率分别达到99％和95％以上。废铁屑经8次使用后仍有良好的处理效果。研究了各种相关因素对染料废水脱色的影响。     

Coupling effects of the explosion shock wave and heat radiation on the dynamic response of a fixed-roof tank

The occurrence of leakage in large tank farms or oil deposits can lead to fire or explosion accidents. Coupling effects of fire and explosion loadings can cause considerably more damage to adjacent tanks or buildings than either loading individually does. In this study, the combined loadings of the explosion shock wave and heat radiation from a pool fire on a neighboring empty fixed-roof tank were numerically investigated. The effects of the explosion shock wave intensity and relative height of the explosion center [the ratio of the height of the explosion center to the height of the tank (h_r)] were analyzed. The results indicate that tanks damaged by explosion shock waves have decreased fire resistance and critical buckling temperature. Moreover, the thermal buckling deformation of the predamaged tank largely depends on the explosion shock wave. With an increase in the explosion shock wave intensity or a decrease in h_r, the explosion shock wave has greater influence on the fire resistance of the tank, and the critical buckling temperature decreases. This paper can provide an understanding of the dynamics of a tank under explosion shock wave loading, and of the critical failure criterion and failure modes of a target tank under the coupled loading of the explosion shock wave and an adjacent pool fire.     

紫外线B对海洋生态系统的影响

近年来随着臭氧损失现象日益严重，到达地球表面的紫外线B辐射不断加强，海洋生态系统受到了前所未有的威胁。UV-B的增强改变了生物体赖以生存的水体环境，影响了浮游植物对营养盐的吸收同化，抑制了浮游植物的光合作用，从而减少了海洋对CO2的吸收能力，其结果直接增加了温室效应。同时UV-B也直接影响生态系统食物链的各个营养级，伤害海洋病毒、细菌和浮游植物，降低浮游动物和仔稚鱼的成活率，进而影响到整个海洋生态系统的结构和功能。     

有机磷农药降解菌的紫外诱变育种

有机磷农药降解菌地衣芽孢杆菌（ Ｂａｃｉｌｌｕｓｌｉｃｈｅｎｉｆｏｒｍｉｓ） 经紫外线诱变后,筛选出突变菌株Ｐ１２ ．在θ＝３０℃,溶解氧ρ（Ｏ２） ＝２ ．５ ｍｇ Ｌ－１ 的培养条件下,３ ｄ 内对甲胺磷的降解率为８０ ．１％ ,比出发菌株提高了将近１０％的降解率．农药斜面连续传代１０ 次,降解活力保持稳定．     

Comparison of the daily global solar radiation from different data sources in Northwest China climate

The solar radiation data are of high importance to the solar energy systems. Conventional methods to obtain the solar radiation data are from weather stations, solar radiation models, commercial software databases, and field measurements. In the present study, a new daily global solar radiation model is proposed, by combining the quadratic function of sunshine fraction and sine function of the day of the year. The solar radiation model calculated data are then compared with China Meteorological Data Sharing System (CMDSS) data, TRNSYS data, and field-measured data in Northwest China climate. It is found that the newly proposed solar radiation model has better performance than the other nine solar radiation models in the literature. The solar radiation model calculated data fit well with the CMDSS annually average data. The TRNSYS data are a bit larger than the CMDSS annually average data in summer half year and a little smaller than those in winter half year. The solar radiation model and the CMDSS annually average data have the best correlation, whereas the TRNSYS data and the field-measured data have the worst correlation. The solar radiation model calculated data have the best correlation with the other three data sources.     

核电燃料元件厂环境辐射监测与评价

本文对 1994～ 1998年核电燃料元件生产所排放的放射性流出物及环境辐射进行了监测分析。结果表明 ,在正常生产运行情况下 ,放射性流出物对周围公众造成的年最大个人有效剂量当量是 7 2 6× 10 -2 mSv ,远低于公众剂量限值。评价半径为80km范围内的集体有效剂量当量为 4 70× 10 -2 人·Sv/a。