水田甲烷排放研究进展

本文对水田甲烷排放通量的研究进展及有关的土壤和环境因素作了综述。指出用于减少水田甲烷排放的措施不应导致水稻的减产和引起其它温室气体排放的增加。应开展落干期间水田作为大气甲烷汇的作用的研究。     

转cry1Ab基因水稻中毒蛋白的表达、分泌及其在土壤中的残留

研究了转cry1Ab基因水稻(克螟稻)中Cry1Ab毒蛋白的表达、根系分泌及其在土壤中的残留规律.结果表明,分蘖始期至成熟期,克螟稻地上部和根部中的Cry1Ab毒蛋白的表达量(FW)分别为3.23～8.22 μg/g和0.68～0.89 μg/g.生育期间克螟稻根系分泌的Cry1Ab毒蛋白含量仅为1.66～48.02 ng/(株·d).试验证实,克螟稻根际土中的Cry1Ab毒蛋白残留含量低于检测限(<0.5ng/g 干燥土).生物测定还表明,克螟稻根际土及其提取液对棉铃虫初孵幼虫和3龄幼虫不产生致死性效应.相对于Cry1Ab毒蛋白的根系分泌转移,克螟稻秸秆还田对土壤环境的影响应引起重视.     

稻田土菌群驯化对稻秆两步发酵产甲烷效果的影响

为提高稻秆的降解率及其厌氧发酵甲烷产量,采用高氨氮畜禽废水作为氮源以驯化稻田土壤微生物,优化其降解稻秆的初始pH值,并评估水解产物液体发酵产甲烷性能.结果表明,混合组驯化的微生物产纤维素酶活性及对稻秆木质素的降解率高于其它组及先前文献报道,分别达到4.01 IU和51.96%,且后期水解液中总有机碳（Total organic carbon, TOC）及还原糖含量最高.随着初始pH值的提高,稻秆中纤维素、半纤维素和木质素的降解率显著增加,稻秆水解液中的挥发性脂肪酸（Volatile fatty acids, VFAs）和TOC含量均显著增加,并在第7 d达到最高值.将水解稻秆7 d的水解液进行厌氧发酵显示,在初始pH=9.0条件下累积甲烷产量达到最大,为37.60 mL·mL^-1水解液.本实验结果表明, 驯化的稻田土微生物在碱性条件下可以更有效地降解稻秆,提高水解液中TOC及VFAs含量,从而提高厌氧发酵的甲烷产量.     

Higher-efficiency for combined photovoltaic-thermoelectric solar power generation

Solar energy application in a large spectrum has the potential for high-efficiency energy conversion. Though, solar cells can only absorb photon energy of the solar spectrum near their band-gap energy, and the remaining energy will be converted into thermal energy. The use of the thermoelectric generator becomes a necessity for convert this thermal energy dissipated so as to increase efficiency conversion.

This paper analyses the feasibility of photovoltaic-thermoelectric hybrid system and reviews their performance in order to optimize harvested energy. Regarding the thermoelectric effect, a new method of the ambient energy harvesting is presented. This method combines thermoelectric generators and the effects of heat sensitive materials associated to photovoltaic cells in phase change for generating both energy day and night. Experimental measures have been conducted primarily in laboratory conditions for a greater understanding of hybridization phenomena under real conditions and to test the actual performance of devices made. Results show that the hybrid system can generate more power than the simple PV and TEG in environmental conditions. This hybrid technology will highlight the use of renewable energies in the service of the energy production.     

The impact of coal and non-coal consumption on China's energy performance improvement

China is the world's largest energy consumer, and coal accounts for a higher proportion of the country's total energy consumption, yet during its 12th five-year plan (2011–2015), the coal share among total energy consumption significantly decreased. Previous studies exploring energy performance typically used energy consumption as an input, but this lacks the analytical capacity for the structure of energy consumption. Thus, this study splits energy input into two different inputs, coal consumption and non-coal energy consumption, and based on their differences with other variables, uses the hybrid dynamic data envelopment analysis model to assess the energy performance of China's provincial industrial sector during the period 2011 to 2015. We then compare coal consumption's and non-coal consumption's rooms for improvement and conclude that provinces in eastern and central China should reduce the amount of coal consumption, thereby improving energy performance. Conversely, provinces in the western region should target a balance between energy utilization efficiency and coal consumption.     

水稻田的甲烷释放特性及其生物学机理

本文报导采用土柱法和田间原位法研究渍水稻田甲烷释放特性的结果。不同生育期的测定表明,早稻以分蘖盛期时释放量最大,以后逐渐减少,晚稻从分蘖始期起逐渐增加,至分蘖盛期、末期时达到最大,随后在孕穗期急剧减少,至生长后期又有所回升。以原位法测定表明,晚间和上午释放的甲烷量较多,中午几乎无甲烷释放,下午又有少量释放。不同施肥区稻田甲烷释放量明显不同,以施猪粪有机肥区为最高,次为施尿素无机氮区,不施肥区最低。但各施肥区水稻不同生育期的甲烷释放趋势完全一致,以分蘖期释放量最大,稻田释放的甲烷主要是稻植株释放的,可占总释放量的85％以上。行株间土壤释放的量不多。田间水释放极少,就植株而言,甲烷释放部位主要是在与土壤密切结合的未扰动的根基和根系部位,水面下茎秆白色部分和水上绿色部分几乎无释放。根系也主要是靠近根基的上半部分,根尖部位甲烷形成活性明显小得多。且研究表明,产甲烷细菌附存于根表而不进入根内组织。根际土壤中产甲烷细菌、厌氧性纤维素分解细菌和甲烷氧化细菌的数量以及总挥发有机酸含量都明显高于和行间土壤。     

绿磺隆对水稻的残留危害剂量

用田间模拟试验法，研究了土壤中绿磺隆不同添加量与水稻危害剂量的关系。结果表明：稻田绿磺隆添加量超过０．３７５ｇ（ＡＩ）／ｈｍ￣２时，就可能对水用产生危害，在此用量水平下，绿磺隆在耕层土壤中的平均残留浓度为０．１７μｇ／ｋｇ，按此推算，麦田按正常用量的２倍量（３０ｇ／ｈｍ￣２）施用，在种麦期间绿磺隆在麦田土壤中的半衰期超过３２．１ｄ．即会对水稻产生危害。     

水分调节材料对牛粪堆肥氨气挥发的影响

利用通风式堆肥发酵方式研究了牛粪堆制过程中氨气的挥发特征和锯末、稻壳、稻草等不同水分调节材料对氨气挥发的影响。结果表明,牛粪堆制过程中主要在前期,尤其是在最初的2周内释放氨气;堆肥期间挥发的氨态氮约为牛粪总含氮量的17%～50%。不同水分调节材料都可以在一定程度上抑制氨气的挥发,但锯末抑制氨气挥发效果最好,其次是稻壳,稻草抑制氨气挥发的效果较小。因此,为了减少氮素损失,应采取适当措施抑制氨挥发或回收挥发的氨气。     

绿黄隆在麦茬土壤中的残留及其对后茬水稻的影响

应用核素示踪技术，以１４Ｃ－绿黄隆进行麦茬土壤残留及其对后茬水稻影响的盆栽试验研究。结果表明，施于麦地的绿黄隆经过麦季（２０６ｄ）后有２５％～３０％残留于土壤；经过麦－稻两季（３２６ｄ）后仍有约１５％的绿黄隆残留在土壤中；麦茬土壤中残留的绿黄隆严重影响后茬水稻根系生长，进而影响植株的生长发育；水稻植株残留量和转移系数是根系＞＞茎叶＞稻谷，在各部位的分布是不均匀的。     

控制稻田甲烷排放的农业耕作条件的研究

在1990—1992年期间中国环境科学研究院观测了北京地区洼里乡的稻田中甲烷的排放情况。其间农田中施用了有机堆肥和几种化学肥料,以观察化学肥料和有机肥料对甲烷排放的影响。结果显示,在通常的农业耕作条件下本地区甲烷排放水平为17.6mg/m~2·h,并且在整个生长期中间有两个排放高峰,高峰期甲烷排放量占全年排放总量的65％以上,试验结果还显示有机肥料具有增加甲烷排放的作用;化学肥料,如硫胺、尿素等,在其有效作用期间,有抑制甲烷排放的作用,间歇灌溉是有效控制甲烷排放的方法之一。