喷灌和沟灌方式对农田土壤NH3挥发的影响

研究了2016和2017年传统灌溉（沟灌）和节水灌溉（喷灌）方式氨（NH₃）挥发的季节年际动态变化特征及其影响因素.采用通气法进行原位监测,分析了土壤温度、体积含水量、铵态氮（NH₄⁺-N）、硝态氮（NO₃^--N）以及气温降水等因素对NH₃挥发的影响.结果表明,NH₃挥发速率的峰值出现在施用氮肥后1~2周,喷灌有效降低NH₃挥发峰值,喷灌和沟灌的NH₃挥发速率峰值在2016年分别为2.67kg/（hm²·d）和11.11kg/（hm²·d）,2017年分别为2.42kg/（hm²·d）和11.73kg/（hm²·d）;马铃薯生长季NH₃挥发存在明显的季节变化,挥发高峰主要发生在7~8月,追肥期高于基肥期.2016~2017年农田土壤NH₃累积挥发量均表现为喷灌<沟灌,与沟灌相比,喷灌分别减少58.15%和43.55%.NH₃挥发速率与土壤温度呈显著正相关（P<0.05）,与体积含水量、NH₄⁺-N、NO₃^--N浓度呈极显著正相关（P<0.01）.     

1979-2014年中国地面风速的长期变化趋势

基于中国国家级地面气象站均一化风速月值数据集,采用线性回归等方法分析了1979-2014年中国2268个台站地面风速演变的时空特征。结果表明：中国地面风速总体呈显著下降趋势,年平均风速变化速率为-0.142 m/s/10 a;四个季节中春季平均风速下降趋势（-0.18 m/s/10 a）明显大于其他三个季节,其次依次为冬季（-0.135 m/s/10 a）、夏季（-0.13 m/s/10 a）及秋季（-0.129 m/s/10 a）;研究选取的台站中约82%的台站风速呈现下降趋势;划分的七个区域中,高原区和东北区风速下降趋势最明显,华北区下降趋势最小,但都通过了0.05显著性检验;中国地面风速在1980s下降趋势最显著（-0.235 m/s/10 a）,1990s下降趋势减缓（-0.112 m/s/10 a）,2000-2014年下降趋势最小,为-0.099 m/s/10 a;研究期间地面风速与地面气温呈显著负相关,表明近期中国气温变暖可能导致风速减弱。     

抑制剂对淹水土壤反硝化和氨挥发的影响

通过室内培养试验,设置3个硝化抑制剂双氰胺（DCD）（氮肥用量的2.5%（DCD1）、5.0%（DCD2）、7.5%（DCD3））,3个脲酶抑制剂氢醌（HQ）（氮肥用量的0.1%（HQ1）、0.3%（HQ2）、0.5%（HQ3））和3个硝化抑制剂DCD+脲酶抑制剂HQ联合施用（氮肥用量的2.5%+0.1%（HH1）、5.0%+0.3%（HH2）、7.5%+0.5%（HH3））试验处理,探讨抑制剂联合施用对淹水土壤反硝化和氨挥发过程及其环境因子的影响,并借助通径分析探讨环境因子对反硝化和氨挥发过程的影响程度,探求抑制剂、氮素转化过程及其环境因子之间定量影响关系.结果表明,单独施用硝化抑制剂DCD能显著减少反硝化速率,但是增加氨挥发损失.单独施用脲酶抑制剂HQ能不同程度减少氨挥发损失,但对反硝化作用效果不稳定.而联合施用DCD和HQ,尤其是HH2（5.0%的DCD+0.3%的HQ）联合施用可有效地同时抑制反硝化和氨挥发损失,相比CK,其反硝化和氨挥发速率分别减少31.3%和12.5%.通径分析发现,硝化抑制剂DCD和脲酶抑制HQ主要影响土体NO₃^--N和NH₄⁺-N浓度、上覆水体NH₄⁺-N和DON浓度,从而影响反硝化和氨挥发速率.     

Effect of Trichoderma viride biofertilizer on ammonia volatilization from an alkaline soil in Northern China

Ammonia(NH3) volatilization is one of the primary pathways of nitrogen(N) loss from soils after chemical fertilizer is applied, especially from the alkaline soils in Northern China, which results in lower efficiency for chemical fertilizers. Therefore, we conducted an incubation experiment using an alkaline soil from Tianjin(p H 8.37–8.43) to evaluate the suppression effect of Trichoderma viride(T. viride) biofertilizer on NH3 volatilization, and compared the differences in microbial community structure among all samples. The results showed that viable T. viride biofertilizer(T) decreased NH_3 volatilization by 42.21% compared with conventional fertilizer((CK), urea), while nonviable T. viride biofertilizer(TS) decreased NH_3 volatilization by 32.42%. NH_3 volatilization was significantly higher in CK and sweet potato starch wastewater(SPSW) treatments during the peak period. T. viride biofertilizer also improved the transfer of ammonium from soil to sweet sorghum. Plant dry weights increased 91.23% and 61.08% for T and TS, respectively, compared to CK. Moreover, T. viride biofertilizer enhanced nitrification by increasing the abundance of ammonium-oxidizing archaea(AOA) and ammonium-oxidizing bacteria(AOB). The results of high-throughput sequencing indicated that the microbial community structure and composition were significantly changed by the application of T. viride biofertilizer. This study demonstrated the immense potential of T. viride biofertilizer in reducing NH_3 volatilization from alkaline soil and simultaneously improving the utilization of fertilizer N by sweet sorghum.     

氮肥与DCD配施对棚室黄瓜土壤NH3挥发损失及N2O排放的影响

以传统水氮管理为对照,进行了优化水氮管理条件下氮肥与DCD配施对大棚黄瓜土壤氨挥发损失及氧化亚氮排放的影响研究.试验结果表明,与传统水氮管理相比,优化水氮管理减少了氮肥用量及灌水量,但黄瓜产量并没有降低.各水氮处理的NH3挥发速率峰值出现在施肥灌水后的第3d,添加DCD的各优化水氮处理与传统水氮处理相比,土壤氨挥发累积量分别减少55.97%、43.68%、66.47%,4次追肥后W2N2+DCD、W2N3+DCD和W2N4+DCD的氨挥发速率峰值与累积量变化范围较小.不同水氮处理的N2O排放通量的峰值均出现在施肥灌水后的第4d,各追肥时期W2N2+DCD、W2N3+DCD和W2N4+DCD处理,土壤N2O排放通量峰值与N2O累计排放量均显著低于传统水氮处理W1N1,并且3个处理之间不存在显著差异,充分表明优化水氮管理中将氮肥与DCD配施对减少N2O排放起到了显著作用.     

Influence of season,ventilation strategy,and slurry removal on methane emissions from pig houses

About 60% of the global methane emission is related to anthropogenic activities such as agriculture, fossil fuel use, and waste disposal. A significant part of agricultural methane emissions originates from pig husbandry, with indoor stored pig slurry as the main source. In general, the release of methane from indoor slurry storage can be influenced by availability of oxygen and volatile solids, pH value, substrate temperature, retention time, and presence of inhibiting compounds. Investigations on methane release from a pig house with indoor slurry storage were carried out from October 1999 until February 2001 and from February 2003 until July 2004, respectively. The season, in which the fattening period was accomplished, had a significant influence on the level of the methane emission rate, with increased emissions during summer. However, a clear influence of the indoor temperature – and therefore of the ventilation strategy – on the level of the methane emission rate was only found for mean daily temperatures above 25 °C. Methane emissions were reduced significantly due to complete slurry removal between the fattening periods and subsequent cleaning of the slurry pits.     

优化施氮对河套灌区氧化亚氮排放和氨挥发的影响

以河套灌区盐化潮土为研究对象,采用静态暗箱-气相色谱法和通气法研究了4个施肥处理(不施肥(CK)、传统施肥(CON)、优化处理1(OPT1,减氮53.3%)、优化处理2(OPT2,减氮53.3%+硝化抑制剂))对河套灌区玉米农田氧化亚氮(N_2O-N)排放、氨挥发(NH_3-N)损失和玉米产量的影响.结果表明:氮肥减量显著降低了土壤N_2O-N排放和NH_3-N挥发;相比于CON处理,OPT1处理的N_2O-N排放量和NH_3-N挥发量分别降低了45.2%和68.8%(p0.05),但N_2O-N损失氮素比率增加了9.7%(p0.05).施用硝化抑制剂可显著降低土壤N_2O-N排放,与OPT1处理相比,OPT2处理可降低34.6%(p0.05)的N_2O-N排放和41.5%(p0.05)的N_2O-N损失氮素比率,但NH_3-N挥发增加了47.5%(p0.05).OPT1处理显著降低了玉米产量,降幅达22.1%(p0.05),而OPT2处理相对于OPT1处理增产32.9%(p0.05),与传统施肥处理无差异.因此,综合N_2O-N排放、NH_3-N挥发及玉米产量可知,OPT2是较为合理的施肥措施,值得在河套灌区推广.     

Methane,nitrous oxide and ammonia emissions during storage and after application of dairy cattle slurry and influence of slurry treatment

Slurries are a significant source of CH₄, NH₃ and N₂O emissions to the atmosphere. The research project aimed at quantifying CH₄, NH₃ and N₂O emissions from liquid manure stores and after manure application under field conditions. The influence of the manure treatment options “no treatment”, “slurry separation”, “anaerobic digestion”, “slurry aeration” and “straw cover” on the emission level was investigated. Approximately 10 m³ of differently treated slurry were stored in pilot scale slurry tanks. Emissions were followed for c. 80 days. After the storage period, slurries were applied to permanent grassland. Greenhouse gas emissions from slurry were mainly caused by methane emissions during storage and by nitrous oxide emissions after field application of manures. Mitigation of GHG emissions can be achieved by a reduction in slurry dry matter and easily degradable organic matter content. Ammonia emissions mainly occurred after field application. Untreated slurry emitted 226.8 g NH₃ m⁻³ and 92.4 kg CO₂ eq. m⁻³ (storage and field application). Slurry separation (liquid fraction and composting of the solid fraction) resulted in NH₃ losses of 402.9 g m⁻³ and GHG losses of 58.5 kg CO₂ eq. m⁻³. Anaerobic digestion was a very effective means to reduce GHG emissions. 37.9 kg CO₂ eq. m⁻³ were lost. NH₃ emissions were similar to those from untreated slurry. Covering the slurry store with a layer of chopped straw instead of a wooden cover increased NH₃ emissions to 320.4 g m⁻³ and GHG emissions to 119.7 kg CO₂ eq. m⁻³. Slurry aeration nearly doubled NH₃ emissions compared to untreated slurry. GHG emissions were reduced to 53.3 kg CO₂ eq. m⁻³.     

生物沥浸法去除猪粪中重金属和提高其脱水性能研究

采用复合嗜酸性硫杆菌,通过摇瓶试验研究了不同Fe2+添加量下生物沥浸对含固率为3%的猪粪中重金属的去除和脱水性能的影响.同时,考察了不间处理的pH、氧化还原电位(ORP)、Fe2+、Fe3+、总Fe、Cu、Zn、比阻和毛细吸水时间(CST)的变化.结果表明,采用生物沥浸技术能有效地去除猪粪中的重金属,随着Fe2+添加量...     

Measurements of wind speed and plume rise with a rapid-scanning Lidar

A series of 30-min means of plume rise and dispersion parameters were measured at Fawley power station on Southampton Water between May and December 1989 using a rapid-scanning Lidar. Where possible, plume parameters were determined at three distances, typically 250, 750 and 1500 m, from the stack. Simultaneous measurements of temperature profiles were made using model aircraft and of wind speed and direction using a cup anemometer and wind vane at a height of 44 m on a transmission tower. By matching time series of plume heights at different distances, absolute measurements of wind speed at plume height could be made. These measurements gave a more reliable estimate of plume rise than did surface wind speeds. It was found that, for travel distances out to 1.5 km, the Briggs formula gave a robust prediction of plume heights with C₁ = 1.38±0.07 (95% confidence limits). At Fawley, the standard error in the predicted plume height at 500 m was then 21.0 m, or 19% of the 30-min mean plume rise. For plume-level winds of less than 20 m s⁻¹, analysis of the dependence of plume height on distance, wind speed and power-station load gave a virtual source height of 195.2±10.3 m (95% confidence limits). This is identical with the physical stack height of 198.1 m.     

Effectiveness of a fixed-depth sensor deployed from a buoy to estimate water-column cyanobacterial biomass depends on wind speed

Water quality sondes have the advantage of containing multiple sensors,extended deployment times,high temporal resolution,and telecommunication with stakeholder accessible data portals.However,sondes that are part of buoy deployments often suffer from typically being fixed at one depth.Because water treatment plants are interested in water quality at a depth of the water intake and other stakeholders (ex.boaters and swimmers) are interested in the surface,we examined whether a fixed depth of app...     

黄土及其他添加物对猪粪贮存过程氨气和温室气体排放的影响

畜禽粪肥在贮存阶段养分损失严重,是CO_2、CH_4、NH_3和N_2O等大气污染物的重要排放来源.本文采用室内培养方法,研究了添加黄土、秸秆、生物炭和膨润土对猪粪贮存过程中氨气及温室气体排放的影响.结果表明,添加10%用量的生物炭和膨润土处理的CO_2累积排放量与不添加任何添加物的猪粪对照相比分别降低了15.4%和20.9%,N_2O累积排放量分别降低了19.8%和37.6%.添加膨润土处理的NH_3损失量显著增加,但添加生物炭和膨润土处理的综合温室效应与猪粪对照相比均显著降低.添加10%秸秆处理的CH_4和NH_3累积排放量分别较猪粪对照降低了56.8%和95.8%,但其综合温室效应与对照相比差异不显著.模拟黄土垫圈过程添加黄土处理的氨气及温室气体累积排放量均显著降低,综合温室效应显著低于其他处理(p0.05).可见,黄土垫圈是保蓄粪肥碳、氮养分的有效措施,猪粪贮存阶段添加少量生物炭、膨润土对于减少粪肥综合温室效应具有积极作用.     

机动车排放污染的速度-加速度耦合影响分析

利用OBS-2200车载测试系统,分别在高峰期、平峰期和低峰期的天津市典型路段进行了车载测试,并获得了碳氢化合物(HC)、一氧化碳(CO)和氮氧化物(NOx)等车辆排放的污染物的逐秒数据.结果显示在这3个时段内,车辆的加速度大都集中在-1.5~1.5m/s2,速度大都集中在0~70km/h,并且HC、CO和NOx的最高排放率为0.0673、0.706和0.0178g/s,都集中在高速(速度(v)>30km/h, 加速度(a)>0.5m/s2)工况范围内.通过拟合发现,HC、CO和NOx的排放率与比功率(Vehicle Specific Power,简称VSP)之间的拟合决定系数分别为0.71、0.86和0.85,相关性较高,说明VSP可以作为评价车辆排放率的一个重要参考性指标.     

Ammonia volatilization losses and balance from urea applied to rice on a paddy soil

Ammonia volatilization loss and 15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4+-N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%-38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. 15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency.     

温度和氨氮浓度对水体N2O释放的影响

氧化亚氮的释放已经成为了一个全球性的环境问题,水体中N₂O的释放量会随着氮含量的增加而增加.本文通过微宇宙系统的构建,分析氮的转化过程和氮转化基因的变化,并结合结构方程模型分析了温度、氨氮含量对水体N₂O释放的贡献.研究结果发现氨氧化古菌和反硝化细菌丰度均与N₂O释放呈正相关,表明水体中的硝化和反硝化作用都会造成N₂O的释放.氨氮浓度的升高并不直接促进N₂O的释放,而温度和通过硝化作用产生的硝态氮对N₂O的释放有促进作用.此外,硝化速率通过促进亚硝态氮和反硝化菌的丰度而间接地促进N₂O的释放.     

The governance of private residential land in cities and spatial effects on tree cover

Trees in cities supply ecosystem services, including cooling, storm water quality management, habitat, visual screening and softening of built form. There is an expanding interdisciplinary field encompassing biodiversity, ecosystem services, and stewardship networks in cities. However most of this work focuses on public greenspace. While much work has been done to demonstrate that trees on private land are an important complement to the public urban forest, and to understand the social drivers of such, less is known about the governance of private greenspace in cities. Private land contributes to a significant component of a city’s tree cover, particularly in cities characterised by low-density residential suburbs. It is important to understand the mechanisms that govern private tree cover, given the pace and scale of urbanisation globally. We combined policy and spatial analysis to examine the influence of larger and denser forms of residential development on suburban tree cover and the scope of contemporary governance measures. We interrogated tree cover patterns in the rapidly densifying and consolidating city of Brisbane, Australia, to show that private residential tree cover is explained by dwelling density, housing age, terrain slope, high school education, and household income. Results show significantly (30%) less tree cover in low-density residential suburbs developed since the early 1990s. We develop five governance principles for reversing the decline of urban trees on private residential property that may be transferable to other rapidly developing cities in around the world.     

Characteristics of volatile compounds removal in biogas slurry of pig manure by ozone oxidation and organic solvents extraction

Biogas slurry is not suitable for liquid fertilizer due to its high amounts of volatile materials being of complicated composition and peculiar smell. In order to remove volatiles from biogas slurry efficiently, the dynamic headspace and gas chromatography-mass spectrometry were used to clear the composition of volatiles. Nitrogen stripping and superfluous ozone were also used to remove volatiles from biogas slurry. The results showed that there were 21 kinds of volatile compounds in the biogas slurry, including sulfur compounds, organic amines, benzene, halogen generation of hydrocarbons and alkanes, some of which had strong peculiar smell. The volatile compounds in biogas slurry can be removed with the rate of 53.0% by nitrogen stripping and with rate of 81.7% by the oxidization and stripping of the superfluous ozone. On this basis, the removal rate of the volatile compounds reached 99.2% by chloroform and n-hexane extraction, and almost all of odor was eliminated. The contents of some dissolved organic compounds decreased obviously and however main plant nutrients had no significant change in the biogas slurry after being treated.     

Ammonia volatilization losses and 15N balance from urea applied to rice on a paddy soil

Ammonia volatilization loss and ^15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4^＋-N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%-38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. ^15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency.     

海面风矢量对不同极化状态海表面亮温的遥感影响研究

本文从海面风矢量与不同极化状态下海表面亮温参数的关系入手,利用2014年5月1日西北太平洋区域Windsat卫星L2风场数据和SMOS（Soil Moisture and Ocean Salinity）卫星L1C数据,定量分析了风速和风向对亮温的影响。研究结果表明:海表面亮温的变化,风速大于风向的影响;V极化状态下垂直亮温对风速、风向的敏感性最强,Stokes2亮温参数对风速的敏感性最低,20°风向变化对Stokes1亮温参数敏感性最低;海面亮温在3级风速内和0°~150°风向区间受风场影响变化较小,亮温波动显著区域主要集中在6级风速以上和300°~360°风向区间。     

Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products(DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine(NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes.The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon(PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than67% ammonia and 70%–100% N-nitrosamine precursors were removed by Mordenite zeolite(except 3-(dimethylaminomethyl)indole(DMAI) and 4-dimethylaminoantipyrine(DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors(dimethylamine(DMA), ethylmethylamine(EMA), diethylamine(DEA), dipropylamine(DPA), trimethylamine(TMA), DMAP, and DMAI) during the alum coagulation process.