Time scales in atmospheric chemistry: coupled perturbations to N2O, NOy, and O3

Nitrous oxide (N2O) is one of the top three greenhouse gases whose emissions may be brought under control through the Framework Convention on Climate Change. Current understanding of its global budget, including the balance of natural and anthropogenic sources, is largely based on the atmospheric losses calculated with chemical models. A representative one-dimensional model used here describes the photochemical coupling between N2O and stratospheric ozone (O3), which can easily be decomposed into its natural modes. The primary, longest lived mode describes most of the atmospheric perturbation due to anthropogenic N2O sources, and this pattern may be observable. The photolytic link between O3 and N2O is identified as the mechanism causing this mode to decay 10 to 15 percent more rapidly than the N2O mean atmospheric lifetime, affecting the inference of anthropogenic sources.     

Ice core records of atmospheric N2O covering the last 106,000 years

Paleoatmospheric records of trace-gas concentrations recovered from ice cores provide important sources of information on many biogeochemical cycles involving carbon, nitrogen, and oxygen. Here, we present a 106,000-year record of atmospheric nitrous oxide (N2O) along with corresponding isotopic records spanning the last 30,000 years, which together suggest minimal changes in the ratio of marine to terrestrial N2O production. During the last glacial termination, both marine and oceanic N2O emissions increased by 40 +/- 8%. We speculate that our records do not support those hypotheses that invoke enhanced export production to explain low carbon dioxide values during glacial periods.     

马铃薯施用Mg·N·P_2O_5·K_2O肥优化数学模型研究

采用二次回归正交旋转组合设计方法研究Mg、N、P2O5、K2O施用量与马铃薯生产成本、纯收入及产投比的关系,建立了马铃薯生产成本、纯收入及产投比与Mg、N、P2O5、K2O施用量间的优化数学模型。在对模型进行深入分析的基础上,作了计算机模拟试验,提出了2套马铃薯高产、高效栽培的施肥模型:纯收入高于9 000元/hm2,产投比高于2.21时的施肥量为Mg肥(MgSO2)15.697 5～18.742 5kg/hm2,N肥(纯N)35.100 0～45.137 5 kg/hm2,磷肥(P2O5)97.47～155.52 kg/hm2,K肥(K2O)125.685～149.445 kg/hm2。纯收入高于10 000元/hm2,产投比高于3.0施肥量为Mg肥(MgSO2)16.485～27.765 kg/hm2,N肥(纯N)9.552 5～44.697 5 kg/hm2,磷肥(P2O5)63.585～129.915kg/hm2,K肥(K2O)为102.802 5～173.947 5 kg/hm2。     

巢湖流域河流沉积物N2O释放对水体溶存N2O贡献研究

2010年11月在巢湖支流丰乐河与杭埠河采用现场培养和实测方法研究了沉积物N2O释放对水体（水柱）溶存N2O的影响,并采用NO-3削减法估算了沉积物的反硝化速率。研究结果表明,丰乐河与杭埠河N2O平均溶存浓度分别为0.26±0.10（SD）μg N-N2O·L-1和0.18±0.04（SD）μg N-N2O·L-1,饱和度分别为186%和151%,表明两条河流为大气N2O的潜在释放源。丰乐河与杭埠河沉积物-水界面N2O平均释放通量分别为0.39±0.44、0.15±0.16 μg N-N2O·m-2·h-1,由此可分别贡献水体中约89% 和45%的溶存N2O。对河流沉积物的反硝化速率估算结果表明,丰乐河与杭埠河沉积物反硝化速率分别为0.12±0.07、0.10±0.05 mg N·m-2·h-1,与已有的沉积物反硝化速率报道相比较低。     

Antarctic Ozone Depletion Chemistry: Reactions of N2O5 with H2O and HCl on Ice Surfaces

The reactions of dinitrogen pentoxide (N(2)O(5)) with H(2)O and hydrochloric acid (HCl) were studied on ice surfaces in a Knudsen cell flow reactor. The N(2)O(5) reacted on ice at 185 K to form condensed-phase nitric acid (HNO(3)). This reaction may provide a sink for odd nitrogen (NO(x)) during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. A lower limit to the sticking coefficient, gamma, for N(2)O(5) on ice is 1 x 10(-3). Moreover, N(2)O(5) reacted on HCl-ice surfaces at 185 K, with gamma greater than 3 x 10(-3). This reaction, which produced gaseous nitryl chloride (ClNO(2)) and condensed-phase HNO(3), proceeded until all of the HCl within the ice was depleted. The ClNO(2), which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide (NO(2)), may be important in the partitioning of NO(x) between gaseous and condensed phases in the Antarctic winter.     

南疆滴灌高产杂交棉花干物质和氮磷钾积累模拟分析

研究南疆覆膜滴灌条件下高产杂交棉干物质和氮磷钾养分的积累规律.结果表明皮棉3 000 kg/hm2高产条件下,棉花总干物质和生殖器官干物质积累速率最快时间在出苗后的107～108和117～118 d;棉株吸收N、P2O5、K2O的快增期分别在出苗后66～153、55～126和62～126 d.高产杂交棉地上部总干物质和生殖器官干物质积累量分别为102.51和62.27 g/株,吸收积累氮磷钾养分的总量换算为N、P2O5、K2O分别为515.3、126.4和591.9 kg/hm2,每生产100 kg皮棉需吸收氮磷钾比例N∶P2O5∶K2O=1∶0.25∶1.15.     

根际反硝化作用与N2O释放

对根际反硝化作用及N2O的释放进行了综述。反硝化过程与N2O的产生及释放有密切的关系。反硝化作用产生的N2O量不仅取决于反硝化速率，而且也取决于那些影响反硝化产物N2O／N2比值的参数。在植物根际这一特殊土壤区域中，反硝化作用受NO3^-,C及O2的综合影响，豆科作物根瘤是一个特殊的根际系统，根瘤菌的反硝化作用及N2O释放应引起更大的关注。植物根际不仅对反硝化作用产生影响，而且对N2O释放也起了重要的通道作用，特别是对渍水土壤有重要的意义。文章最后指出了一些尚需深入研究的问题。     

大豆植株及大豆植株-土壤系统N2O释放规律及其与光合作用的关系

为区分植物在土壤-植物系统N2O排放中的贡献,用封闭式箱法对田间栽培的大豆植株及土壤、大豆植株-土壤系统的N2O排放进行了测定,同时对影响N2O的排放的因素进行了分析。观测结果表明:田间栽培的大豆的N2O排放通量昼间变化模式是10∶30有一个排放高峰,153∶0有一个排放低谷,甚至表现为可吸收大气中的N2O;在生育期内,大豆植株有两个释放高峰,分别位于6月下旬和8月中旬。从6月下旬至8月末,大豆对土壤-植物系统N2O排放的贡献率约为25%～57%。大豆植株、大豆植株-土壤系统N2O排放通量与温度有一定的相关性,相关系数r2分别为0.4954和0.5357,大豆N2O的排放通量同光合速率有一定的相关性(r2=0.5944)。     

Acyl N to O shift in poly-DL-serine

It has been demonstrated that concentrated sulfuric acid causes the polypeptide, poly-DL-serine (MW approximately 5000), to rearrange to the polyester, to the extent of 70 percent of the original number of amide bonds. The remaining hydroxyls of the serine residues become sulfonated.     

氮磷钾与水稻纹枯病发生综合效应研究

采用３因素５水平最优回归设计测定氮磷钾肥对水稻纹枯病发生程度的综合影响效应,结果表明：氮磷钾对水稻纹枯病发生有显著影响,低中水平时,氮肥促进病害发生发展,磷钾肥抑制病情扩展,而高水平时作用效应则与低中水平相反,在目前施服水平下,一般年份都应防治本病１￣２次。     

氮磷钾肥对茎瘤芥产量和硝酸盐的影响

采用田间试验和化验分析的方法,研究了不同氮、磷、钾施用水平下,茎瘤芥各器官产量和硝酸盐含量变化特征.结果表明,瘤茎产量与氮、磷、钾施用量均呈极显著二次回归关系;瘤茎硝酸盐含量与施氮量呈极显著正相关,施磷量(P2O5)在55.8 kg/hm2、施钾量(K2O)在133.5 kg/hm2范围内,增施磷、钾肥可提高瘤茎产量而降低硝酸盐含量.茎瘤芥无公害生产上,应控制氮、磷用量,适当增施钾肥.     

烟台市农田N·P2O5和K2O供需平衡及环境影响研究

通过估算农作物的N、 P₂O₅、K₂O需要量,农作物秸秆的N、 P₂O₅、K₂O还田量,人、畜、禽粪尿的N、 P₂O₅、K₂O还田量和化肥的N、 P₂O₅、K₂O施用量,研究烟台市农田N、 P₂O₅、K₂O供需平衡。结果农作物对N、 P₂O₅、K₂O的需要量分别是146 977.71、60 273.35和130 907.02 t;有机肥的N、 P₂O₅、K₂O还田量分别是89 154.77、45 966.96和97 214.73 t;化肥的N、 P₂O₅、K₂O施用量...     

大豆N2O释放与光照度和光合作用的关系

采用分隔式封闭箱法，测定盆栽大豆植株氧化亚氮（N2O）通量以及光照度、光合速率和气孔导度的日变化。同时，观测田间大豆—土壤系统在主要生长阶段N2O释放的变化。在温室里，大豆植株N2O释放在上午10：00时出现一个高峰；中午时N2O释放量较低，此时光照度和光合速率都保持在较高的水平上；在14：00时，N2O释放量达到低谷,光照度达到最大，但光合速率却处于很低的水平；在15：00时，植株N2O的释放达到第二个高峰，但光照度和光合速率却处于快速下降期。结果表明：植物N2O的释放不仅与光合作用的光反应有关，而且也与暗反应有关。上午10：00以后植株N2O释放通量与气孔导度变化没有一致的关系。在大豆生长季，大豆—土壤系统N2O释放通量有两个高峰，第一个峰出现在6月中下旬，第二个高峰出现在9月下旬。     

华北平原不同作物－潮土系统中N2O 排放量的测定

在中国科学院封丘农业生态试验站应用原状土柱培养法测定了华北平原主要农作物－潮土系统中N     

不同N,P,K肥施用比例对苹果产量影响的研究

本文以苹果为试材,采用不同的N,P,K肥配比试验,介绍了不同肥料配比对苹果产量影响研究的方法和模式,建立了产量与肥料配比之间的关系方程: Y=AN~(b1)P~(b2)K~(b3)。对方程求导确定出其它条件不变的情况下N,P,K肥对产量形成的作用。同时建立了实施计算和比较分析的BASIC程序,并附实例进行分析。     

氮磷钾肥对马铃薯营养状况及块茎产量的影响

试验分别在甘肃省景泰县、内蒙古自治区达拉特旗和河北省沽源县3个马铃薯生产基地进行,在基地常规N、P2O5、K2O肥施用量分别为300、345、375kg/hm2的基础上,研究改变磷、钾、氮肥用量对马铃薯营养状况、块茎产量以及土壤养分的影响。试验结果表明,氮、磷、钾肥用量分别从N300、P2O5345、K2O375kg/hm2降低到180、180、225kg/hm2,对植株干物质累积量没有显著影响,3个基地都呈相同的趋势;3个基地不同处理的块茎产量也没有显著性差异。因此,在试验条件下,氮、磷、钾肥用量和比例为180-180-225的施肥处理,其经济效益较高。施肥对土壤养分含量有较大的影响,特别是磷肥,当施用磷肥后,土壤速效磷含量显著提高,而且主要存在于表层土壤(0￣20cm),这说明缺磷土壤通过施用磷肥,可提高土壤有效磷水平。     

烤烟套种甘薯对烟草氮磷钾营养的影响

通过田间小区试验,研究了烤烟与甘薯套种对烟草氮磷钾素营养的影响.结果表明:烤烟套种甘薯与烤烟单作相比,甘薯吸收了土壤中过多残留的营养元素,土壤营养元素更趋于平衡;增加了土壤耕层中植株的根系,其周围营养元素有效性得以提高,相对含量增加,烟株与环境友好发展,烟株养分得以改善;对烤烟的茎粗、叶厚、株高、叶长、叶宽、有效叶片数等生物学性状未产生不良影响.     

Interception of excited vibrational quantum states by O2 in atmospheric association reactions

Bimolecular reactions in Earth's atmosphere are generally assumed to proceed between reactants whose internal quantum states are fully thermally relaxed. Here, we highlight a dramatic role for vibrationally excited bimolecular reactants in the oxidation of acetylene. The reaction proceeds by preliminary adduct formation between the alkyne and OH radical, with subsequent O(2) addition. Using a detailed theoretical model, we show that the product-branching ratio is determined by the excited vibrational quantum-state distribution of the adduct at the moment it reacts with O(2). Experimentally, we found that under the simulated atmospheric conditions O(2) intercepts ~25% of the excited adducts before their vibrational quantum states have fully relaxed. Analogous interception of excited-state radicals by O(2) is likely common to a range of atmospheric reactions that proceed through peroxy complexes.     

Advances in Nitrogen Denitrification and N2O Emission in Agro-ecosystem

Nitrification and denitrification are two key links of nitrogen flow cycle in soil.N2O and N2,generated from biochemical process of nitrogen,can cause not only the nitrogen losses and reduction of nitrogen use efficiency,but also the boosted concentration of greenhouse gases,severely endangering the environment.Accordingly,nitrification-denitrification has been more and more concerned from whether an agricultural view,or an environmental one.Referring to the related literatures published at home and abroad in recent years,we overviewed the denitrification-caused N loss and N2O emission in various agro-ecosystems,and based on which we put forward countermeasures to reduce the denitrification-caused N loss and N2O emission and its research prospects in the future.