Soil acidification stimulates the emission of ethylene from temperate forest soils

Soil acidification via acid precipitation is recognized to have detrimental impacts on forest ecosystems, which is in part associated with the function of ethylene released from the soil. However, the impacts of acidification on the cycling of ethylene in forest soils have not been fully taken into consideration in global change studies. Forest topsoils (0--5 cm) under four temperate forest stands were sampled to study the effects of a pH change on the emissions of ethylene and carbon dioxide from the soils and concentrations of dissolved organic carbon (DOC) released into the soils. Increasing acidification or alkalinization of forest soils could increase concentrations of DOC released into the soils under anoxic and oxic conditions. The ethylene emission from these forest topsoils could significantly increase with a decreasing pH, when the soils were acidified experimentally to a pH<4.0, and it increased with an increasing concentration of DOC released into the soils, which was different from the carbon dioxide emission from the soils. Hence, the short-term stimulating responses of ethylene emission to a decreasing pH in such forest soils resulted from the increase in the DOC concentration due to acidification rather than carbon mineralization. The results would promote one to study the effects of soil acidification on the cycling of ethylene under different forest stands, particularly under degraded forest stands with heavy acid depositions.     

乙二醇对长毛对虾酸性磷酸酶活力与构象的影响

应用荧光光谱、紫外差示光谱及园二色性光谱等生物物理技术研究长毛对虾酸性磷酸酶经乙二醇微扰后的分子构象变化情况,结果表明乙二醇对酶分子构象有显著的影响。酶的内源荧光强度随乙二醇浓度增大而增强,Ｔｙｒ、Ｔｒｐ残基的微环境发生明显的变化;紫外差示光谱在２２０和２７５ｎｍ出现２个负峰,而２３６ｎｍ出现正峰,２２０和２３６ｎｍ的差吸收与酶分子主链去折叠有关,而２７５ｎｍ主要与Ｔｒｐ残在微环境变化有关;乙二醇     

Synergistic Effects of Nitrogen Amendments and Ethylene on Atmospheric Methane Uptake under a Temperate Old-growth Forest

An increase in atmospheric nitrogen (N) deposition can promote soil acidification, which may increase the release of ethylene (C2H4) under forest floors. Unfortunately, knowledge of whether increasing N deposition and C2H4 releases have synergistic effects on soil methane (CH4) uptake is limited and certainly deserves to be examined. We conducted some field measurements and laboratory experiments to examine this issue. The addition of (NH4)2SO4 or NH4Cl at a rate of 45 kg N ha-1 yr-1 reduced the soil CH4 uptake under a temperate old-growth forest in northeast China, and there were synergistic effects of N amendments in the presence of C2H4 concentrations equal to atmospheric CH4 concentration on the soil CH4 uptake, particularly in the NH4Cl-treated plots. Effective concentrations of added C2H4 on the soil CH4 uptake were smaller in NH+4 -treated plots than in KNO3-treated plots. The concentration of ca 0.3 μl C2H4 L-1 in the headspace gases reduced by 20% soil atmospheric CH4 uptake in the NH4Cl-treated plots, and this concentration was easily produced in temperate forest topsoils under short-term anoxic conditions. Together with short-term stimulating effects of N amendments and soil acidification on C2H4 production from forest soils, our observations suggest that knowledge of synergistic effects of NH+4 , rather than NO3- , amendments and C2H4 on the in situ soil CH4 uptake is critical for understanding the role of atmospheric N deposition and cycling of C2H4 under forest floors in reducing global atmospheric CH4 uptake by forests. Synergistic functions of NH4+ -N deposition and C2H4 release due to soil acidification in reducing atmospheric CH4 uptake by forests are discussed.     

负载镧的EGDE交联壳聚糖微球对氟离子的吸附平衡与吸附动力学

采用负载镧的乙二醇二缩水甘油醚(EGDE)交联壳聚糖微球对含氟水进行吸附处理.该吸附剂的适宜工作条件为:温度30～50℃,pH值7.0,吸附时间30 min.用吸附等温线描述了F-在吸附剂上的吸附平衡,并用动力学模型研究了其吸附动力学机制.结果表明:吸附剂对F-的吸附平衡符合Langmuir吸附等温线和Freundlich吸附等温线,饱和吸附容量为25.7mg·g-1;该吸附剂对F-的吸附既包含化学吸附又包含物理吸附过程,以单分子层的化学吸附为主;吸附动力学符合拟二级动力学方程,吸附过程受化学吸附机理的控制,颗粒内扩散和液膜形成的边界层是其限速步骤.     

Effects of tree species and soil depths on ethylene and methane consumption in tropical and temperate forest soils

To date our knowledge is limited with regard to the responses of ethylene and methane consumption by forest soils to tree species and soil types, and to the effect of presence of ethylene on atmospheric methane consumption. The soils at depths from tropical and temperate forests in China were used to study the responses of ethylene and methane consumption to tree species and soil types. The ethylene and methane consumption by soils beneath each forest floor was measured under the same oxic conditions, along with main properties of forest soils. The accumulation of ethylene was studied in the soil slurry （soil/water, 1/2.5）. In temperate soils under spruce and birch forests, maximal consumption rates of ethylene and methane were observed in the 2.5-5.0 cm and 5.0-7.5 cm soil layers, respectively （P〈0.05）. However, a maximal consumption of both occurred in the 0-2.5 cm soil layer under temperate Korean pine forest （P〈0.05）. Contrary to temperate forest soils, there was a significant lower consumption of ethylene and methane in tropical forest soils at less than 20 cm depths under a seasonal rainforest and secondary rubber forest （P〈0.05）. Hence, the potential of ethylene and methane consumption in the 0-20 cm soil profile was variable with tree species and soil types. According to ethylene formation in the soil slurry, there was greater accumulation of ethylene in the 0-2.5 cm soil under temperate forests than under tropical forests, and its accumulation under spruce and birch forests was more than under Korean pine forest （P〈0.05）. The presence of extrinsic ethylene can significantly inhibit the consumption of atmospheric methane by forest soils.     

Dial Remote Sensed Ethylene and Ozone-Ethylene Correlation in Presence of Urban NOx

{E}thylene, representative of volatile organic compounds and high photochemical ozone creation potential precursor, has been monitored with a single-ended CO₂-TEA laser-based DIAL system using a topographic target. A correlation between ozone concentration and ethylene evolutions in Madrid's urban atmosphere was demonstrated and supported with a basic photochemical smog model. The present work brings additional evidence to the many models which state that ethylene, being a hydrocarbon, has a role to play in the generation of tropospheric ozone.     

低温条件下乙二醇基钻井液体系的试验研究

钻井液在冰点以下能否保持正常的工作性能对低温地层的勘探工作具有十分重要的意义,选择乙二醇作为钻井液的防冻剂可以满足勘探钻进工作的要求。对乙二醇复合聚合物钻井液的耐低温能力、流变性、失水特性以及钻井液的防塌能力进行了试验研究,确定了乙二醇及钻井液中其它聚合物的加量,使其满足低温条件下勘探的要求。     

乙二醛交联氧化淀粉粘合剂的研制

将玉米淀粉用高猛酸钾氧化制得氧化淀粉,用乙二醛进行交联制得粘合剂。实验结果表明,制得的交联氧化淀粉粘合剂的耐水性和干燥速度比普通氧化淀粉粘合剂好。