日本开发成功脱氮新技术

最近日本石川岛播磨重工业公司开发成功废气脱氮新技术,可用于火力发电厂锅炉等设备废气的脱氮处理。这项技术是一种“干式氨接触还原法废气脱氮装置”。锅炉等设备排放出的废气进入该装置后,首先与外部通入的氨混合,然后进入脱氮反应器,与反应器内的催化层发生反应,最后将Nox分解为氮和水蒸汽,排放到大气     

富营养化水体中铵态氮对金鱼藻生长的影响

通过控制pH（7和9）范围以区分分子态氨(NH3)和离子态氨(NH+4)，研究了不同浓度铵态氮(NH+4 N)对金鱼藻生长的影响。研究结果表明：金鱼藻〖JP+1〗相对生长速率的变化范围为每天-010~003。在分子态氨浓度小于022 mg/L时，铵态氮对金鱼藻的毒性是由离子态氨和分子态氨共同作用。在分子态氨达到最大浓度439 mg/L时，〖JP〗金鱼藻的生长速率显著减少，直至死亡。随着铵态氮浓度的增加和胁迫时间的延长，金鱼藻体内碳氮比下降,叶绿素含量下降，光合作用减弱,相对生长速率下降。试验结果为合理利用金鱼藻来改善水质提供科学依据，同时也为研究分子态氨对沉水植物的胁迫作用提供参考。     

克氏原螯虾亚成体和幼体对不同氨浓度水环境的选择

以NH4Cl为主要成分配比成不同浓度的氨溶液，以Y型水迷宫为水环境的选择实验装置，从克氏原螯虾的行为学角度出发，探究其对不同浓度氨溶液的趋避选择性。实验共设置５个浓度梯度：4750、7125、9500、14250和19000 mg/L，其pH值为70，水温为20±05℃。以体长为501±043 cm的克氏原螯虾亚成体及体长为075±015 cm的幼体为实验对象，在Y型水迷宫中的两个选择区中分别放入污水和清水，供实验虾进行选择，记录选择清水和污水的次数及未作出选择的次数，对数据进行非参数检验的二项分布检验。结果表明亚成体在氨浓度4750、7125、9500及14250 mg/L时，没有明显选择性，在氨浓度19000 mg/L时，显著避开污水；幼虾在氨浓度4750 mg/L时，没有明显选择性，在氨浓度7125和9500 mg/L时，显著避开污水，当氨浓度达到14250 mg/L及以上时，出现中毒症状，丧失选择能力。该结果证明克氏原螯虾对高浓度的氨氮型污水不仅没有偏好，而且当浓度达到一定数值时会主动躲避，或躲避不及发生行为异常乃至死亡     

基于DNDC模型的双季稻体系氨挥发损失研究

为了探索长江流域双季稻体系氮肥施用对氨挥发损失的影响，评价Denitrification Decomposition (DNDC)模型对产量和氨挥发拟合的适应性，设计了早稻和晚稻不同氮肥用量田间试验，采用密闭室间歇通气法原位观测氨挥发排放通量，利用DNDC模型进行模拟分析，并运用模拟结果探讨了水稻产量和氨挥发损失与施氮量之间的关系。结果显示，模型能较好模拟双季稻体系水稻产量和氨挥发，早稻、晚稻和双季稻产量模拟值与观测值的相关系数分别为0.994、0.928、0.979，早稻、晚稻和整个双季稻生育期氨挥发模拟值与观测值的相关系数分别为0.994、0.998和0.997，均达到极显著水平。DNDC模型能较好预测因施肥引起的氨挥发排放峰，但在氨挥发通量和排放总量的定量上还需要进一步改进。敏感性指数分析表明，气温是影响作物产量的关键因素，氮肥用量和气温是影响氨挥发的主要因素。DNDC模型在模拟双季稻体系籽粒产量上具有较高的可信度，DNDC模拟和田间观测数据计算的最高产量施氮量分别是420和417 kg·hm^-2。稻田氨挥发损失量与施氮量之间满足二次函数和线性关系，二次函数能更好描述两者之间的关系。为使DNDC更准确的进行估算和应用，有必要获取更翔实的环境资料以减少输入数据的不确定性。     

孔隙水中营养元素的早期成岩模型

基于2002年4、7、11月及2003年2月长江口滨岸潮滩采集的4个点位的柱状沉积物样品，对典型剖面孔隙水中氨态氮和磷酸盐含量的分析测定表明，孔隙水中氨态氮的浓度范围为0．04～16．87mg／L，最高浓度基本都出现在春季；而总可溶磷的浓度为0．01～0．37mg／L，其中大部分的浓度随深度的增加而逐渐升高。通过对长江口滨岸潮滩典型剖面孔隙水中氨态氮和磷酸盐含量变化的综合分析，探讨了研究区域内沉积物的早期成岩作用，并建立早期成岩作用下沉积物孔隙水中氨态氮和磷酸盐的“扩散-平流-反应”模型。研究发现孔隙水中氨态氮地球化学过程主要受有机质分解和粘土矿物的吸附反应控制，而磷酸盐的转移反应主要受有机磷分解、磷酸盐吸附和沉淀的控制。二者反应均遵循一级动力学。     

灌溉和降雨条件下生态沟渠氮、磷输出特征研究

为了研究长沙县金井河流域农业源头生态沟渠氮和磷的输出特征，对灌溉和降雨条件下及不同季节生态沟渠水体氮、磷的变化特征进行监测研究。研究结果表明：灌溉和降雨期间，生态沟渠中总氮的输出最大值为270 mg/L，其输出的主要形态为氨态氮和硝态氮，总磷的最大值达032 mg/L。灌溉后，生态沟渠氮、磷的输出均呈单调递减变化，在灌溉初期均最高。降雨后，总氮、总磷沿程变化趋势均呈递减变化；生态沟渠对水体总氮、总磷去除率分别达64%、70%；各断面氮、磷的输出随着时间的增加呈先增加后降低的趋势，其中总氮、氨态氮含量在雨后第3 d达到最高，总磷含量在雨后第2 d达到最高。在不同季节中水体氮、磷的变化以冬季总氮、氨态氮和磷浓度最高     

嘉陵江（南充段）水体及其底泥中氨氧化微生物群落空间分布特征及其与环境因子关系

为探究人为干扰较多的城市河流中氨氧化微生物的空间变异特征以及影响因素，以嘉陵江（南充段）流域及其城市支流为研究对象，分别采集城市上、中和下游以及流经城区的河流的表层水及其相应底泥，进行理化性质分析和基于16S rRNA基因的Miseq测序分析。结果表明：（1）城市支流水体中的总磷、无机氮和溶解性有机碳显著高于嘉陵江干流。（2）荧光定量PCR分析amoA基因的丰度表明干流中氨氧化古菌（AOA）的丰度总体高于氨氧化细菌（AOB），在水体和底泥中AOA/AOB的比例分别为086~631和179~6985。仅在城市支流水体中AOB的数量高于AOA。（3）嘉陵江水体中主导AOB类群隶属于亚硝化单胞菌属Nitrosomonas cluster 6，而城区支流和靠近排污口的水体和底泥中Nitrosococcus oceani like AOB则为主导AOB类群。（4）水体NH4+-N浓度是影响AOB群落结构空间分布的主导环境因子（P < 005）。（5）该江段中主导AOA类群主要为泉古菌Candidatus Nitrosoarchaeum和Nitrososphaera，且C.Nitrososphaera在城市支流底泥中高度富集。结论综合表明嘉陵江干流和支流氨氧化微生物群落存在显著的空间分异，城市支流及生活污水的汇入是影响其群落特征的主要因素     

长三角地区生态补偿机制效果评估

生态补偿机制是十九大确立的重要制度选择和政策措施,然而实行生态补偿机制是否有效却缺乏理论支持和技术支撑。本文立足于长三角地区,利用IPAT系列模型作为构建模型变量的理论基础,应用合成控制法和断点回归相结合的方法检验了长三角地区生态补偿机制的实施效果以及效果的持续性。合成控制法从基于反事实的视角分析了长三角地区的生态补偿机制,用断点回归分析确认了生态补偿机制的实施引起的断点的存在,而断点回归的分析为生态补偿机制的实施提供了因果推断。为了使得分析结果更为稳健,本文进一步借助安慰剂检验以及Bootstrap安慰剂检验验证了结果的可靠性。模型结论表明,长三角地区的生态补偿机制的实施是有效的。相对于上海市,浙江和江苏两个地区的生态补偿机制实施效果更为明显。进一步做因果推断,结果显示,经济包括隐性经济的发展、工业占比的提高、能源使用的增加以及人口密度的提升会加剧环境污染,依靠研发水平降低环境污染水平的途径仍需进一步探索,而适度的环境管制可以降低环境污染。长三角地区生态补偿机制的成功实践为中国其他地方进一步推行生态补偿机制提供了重要的参考和借鉴价值。     

规模经营主体综合技术效率差异及影响因素——以江苏省水稻生产为例

推动以新型经营主体为依托的粮食规模经营是实现中国乡村振兴的重要路径。基于江苏省水稻规模经营主体调查数据,运用计量分析及DEA-Tobit模型,从主体差异、要素配置、管理营销等方面,实证检验规模经营综合技术效率的差异特征及影响因素。研究表明:现阶段水稻规模经营的综合技术效率处于中等水平,分解后的纯技术效率及规模效率有待提升。规模经营带来了水稻投入成本、总收益及劳动生产率的同步上升,区域差异明显。规模差异比属性差异对综合技术效率及其分解效率的影响更为显著。家庭农场、合作社与企业对综合生产效率的影响依次上升。开展与自身能力相匹配的适度规模经营较为适宜。提高产品价格更能促进各类主体综合技术效率的提升。要素配置及管理经营能力对综合技术效率及其分解效率产生了较为显著的正效应。提高劳动力生产经验及稳定土地流转更有利于综合技术效率的改善。完善价格市场、政府引导技术推广和加大土地连片整治对各种效率的提高也起到积极作用。大力培育各类规模经营主体有助于现代农业经营体系的建立。     

基于RS与GIS的大型滑坡解译——以重庆市武隆县为例

滑坡灾害是当今世界上造成巨大经济损失和人员伤亡的自然灾害之一.自1990年以来,"3S"技术逐渐成为了滑坡灾害信息提取和危险性评价与监测的重要手段.利用RS与GIS技术可以对卫星遥感图像数据、扫描图件和统计资料进行多种形式的数字处理和信息复合,在此基础上采用叠置分析法在同一空间参照系下,将同一地区的地理对象的图层进行叠合,可以产生空间区域的多重属性特征.以滑坡高发区的重庆市武隆县为研究区域,根据TM合成影像中大型滑坡主要的解译标志和实地验证确定了7个滑坡体体积＞1 000 000 m3的大型滑坡,采用叠置分析法成功地提取了这些滑坡及其发育环境的基本信息,为三峡库区大范围滑坡灾害的遥感调查、监测与防治、库区移民安置工作提供参考.     

Emission of ammonia from indoor concrete wall and assessment of human exposure

Addition of urea-based antifreeze admixtures during cement mixing can make it possible to produce concrete cement in construction of buildings in cold weather; this, however, has led to increasing indoor air pollution due to continuous transformation and emission from urea to gaseous ammonia in indoor concrete wall. It is believed that ammonia is harmful to human body and exposure to ammonia can cause some serious symptoms such as headaches, burns, and even permanent damage to the eyes and lungs. In order to understand the emission of ammonia from indoor concrete wall in civil building and assess the health risk of people living in these buildings, the experimental pieces of concrete wall were first prepared by concreting cement and urea-based antifreeze admixtures to simulate the indoor wall in civil building in this work. Then environmental chamber was adopted for studying the effect of temperature, relative humility and air exchange rate on emission of ammonia from experimental pieces of concrete wall. Also the field experiment was made at selected rooms in given civil buildings. Exposure and potential dose of adult and children exposed to indoor/outdoor ammonia in summer and in winter are calculated and evaluated by using Scenario Evaluation Approach. The results indicated that high air exchange rate leads to decreased ammonia concentration, and elevation of temperature causes increasing ammonia concentration and volatilizing rate in chamber. The complete emission of ammonia from the wall containing urea-based antifreeze admixtures needs more than 10 years in general. Ventilating or improving air exchange can play a significant role in reducing ammonia concentration in actual rooms in field experiments. Urea-based antifreeze admixtures in concrete wall can give rise to high exposure and potential dose, especially in summer. Generally, adults have a high potential dose than children, while children have personal average dose rate beyond adults in the same conditions.     

Exhaled NH3 and excreted Nh4+ in children in unpolluted or urban environments

Exhaled ammonia (NH3ex) was measured by chemiluminescence in a group of healthy children (n = 20) and in two groups of asthmatic children, one (Group 1) residing in a National Park in the mountains (n = 68) and other (Group 2) in an urban area (n = 52). We also determined urinary ammonia, nitrates, urea, sodium and potassium normalized to osmolarity. Unlike exhaled nitric oxide (NOex), NH3ex was not specific to asthma as the children in Group 2 and the controls exhaled more ammonia that did the children in Group 1 (14.3 +/- 10.2 and 14.8 +/- 10.3 vs. 5.6 +/- 4.7 ppb; P < .001, respectively). In the urban environment, all children, including the healthy controls, excreted more ammonia (P < .001) and potassium (P < .001) but less urea (P < .02) than did the children residing in the National Park. These manifestations of moderate metabolic acidosis would favor excretion of ammonia at the expense of urea. In the children residing in the National Park, positive correlations were observed between NH3ex and urinary ammonia, and nitrates, age and morphological parameters. The relationship with the morphological parameters is a reflection of the normal physiological formation of NH3ex. In the children residing in the urban area, the other endogenous source of NH3ex was attributed to a slight disturbance in acid-base balance. In conclusion, the measurement of NH3ex appeared of limited interest, although the higher urinary urea/NH4+ ratio in Group 1 (P < .0001), especially in the treated children, appeared to be linked to the lack of atmospheric pollutants in the National Park. Further experimentation is in progress to confirm these findings.     

Airborne reduced nitrogen: ammonia emissions from agriculture and other sources

Ammonia is a basic gas and one of the most abundant nitrogen-containing compounds in the atmosphere. When emitted, ammonia reacts with oxides of nitrogen and sulfur to form particles, typically in the fine particle size range. Roughly half of the PM(2.5) mass in eastern United States is ammonium sulfate, according to the US EPA. Results from recent studies of PM(2.5) show that these fine particles are typically deposited deep in the lungs and may lead to increased morbidity and/or mortality. Also, these particles are in the size range that will degrade visibility. Ammonia emission inventories are usually constructed by multiplying an activity level by an experimentally determined emission factor for each source category. Typical sources of ammonia include livestock, fertilizer, soils, forest fires and slash burning, industry, vehicles, the oceans, humans, pets, wild animals, and waste disposal and recycling activities. Livestock is the largest source category in the United States, with waste from livestock responsible for about 3x10(9) kg of ammonia in 1995. Volatilization of ammonia from livestock waste is dependent on many parameters, and thus emission factors are difficult to predict. Despite a seasonal variation in these values, the emission factors for general livestock categories are usually annually averaged in current inventories. Activity levels for livestock are from the USDA Census of Agriculture, which does not give information about animal raising practices such as housing types and grazing times, waste handling systems, and approximate animal slurry spreading times or methods. Ammonia emissions in the United States in 1995 from sources other than livestock are much lower; for example, annual emissions are roughly 8x10(8) kg from fertilizer, 7x10(7) kg from industry, 5x10(7) kg from vehicles and 1x10(8) kg from humans. There is considerable uncertainty in the emissions from soil and vegetation, although this category may also be significant. Recommendations for future directions in ammonia research include designing experiments to improve emission factors and their resolution in all significant source categories, developing mass balance models, and refining of the livestock activity level data by eliciting judgment from experts in this field.     

丹江口库区典型小流域水体氮素分布特征研究

丹江口水库水质总体良好,但总氮浓度超标问题突出。为明确不同类型小流域氮素的分布和输出特征,优化制定库区控氮措施,选择库周典型小流域,开展水体氮素浓度系统观测和分析。结果显示:(1)余家湾(养殖型)总氮浓度平均为21.23 mg/L,五龙池(村落型)总氮浓度平均为4.00 mg/L,高于钱家沟(自然型)和张沟(农田型);五龙池(村落型)硝态氮浓度最高,平均为2.37 mg/L,张沟最低,平均为1.06 mg/L;余家湾(养殖型)氨氮浓度远高于钱家沟(自然型)、五龙池(村落型)和张沟(农田型)。(2)钱家沟(自然型)氨氮浓度沿程下降趋势显著(p0.05);张沟(农田型)硝态氮(p0.01)和总氮浓度(p0.01)沿程上升趋势显著,坑塘湿地等微地形结构可能是影响小流域氮素的沿程变化的主要因素。(3)钱家沟(自然型)和五龙池(村落型)氮素冬季(12～2月)浓度较高,夏秋季(6～11月)浓度较低,春季(3～5月)波动最大;张沟(农田型)氮素高值出现在6月;余家湾(养殖型)氮素浓度高值出现在8月。(4)余家湾(养殖型)氮素以氨氮为主,五龙池(村落型)、张沟(农田型)和钱家沟(自然型)以硝态氮为主。基于上述结论,后续丹江口库区氮素控制应系统梳理不同类型小流域的分布和数量,重点关注养殖型小流域的氨氮污染和村落型小流域的硝态氮污染。     

Information needs related to extension service and community outreach

Air quality affects everyone. Some people are affected by air quality impacts, regulations, and technological developments in several ways. Stakeholders include the medical community, ecologists, government regulators, industries, technology providers, academic professionals, concerned citizens, the news media, and elected officials. Each of these groups may perceive problems and opportunities differently, but all need access to information as it is developed. The diversity and complexity of air quality problems contribute to the challenges faced by extension and outreach professionals who must communicate with stakeholders having diverse backgrounds. Gases, particulates, biological aerosols, pathogens, and odors all require expensive and relatively complex technology to measure and control. Economic constraints affect the ability of regulators and others to measure air quality, and industry and others to control it. To address these challenges, while communicating air quality research results and concepts to stakeholders, three areas of information needs are evident. (1) A basic understanding of the fundamental concepts regarding air pollutants and their measurement and control is needed by all stakeholders; the Extension Specialist, to be effective, must help people move some distance up the learning curve. (2) Each problem or set of problems must be reasonably well defined since comprehensive solution of all problems simultaneously may not be feasible; for instance, the solution of an odor problem associated with animal production may not address atmospheric effects due to ammonia emissions. (3) The integrity of the communication process must be preserved by avoiding prejudice and protectionism; although stakeholders may seek to modify information to enhance their interests, extension and outreach professionals must be willing to present unwelcome information or admit to a lack of information. A solid grounding in fundamental concepts, careful and fair problem definition, and a resolute commitment to integrity and credibility will enable effective communication of air quality information to and among diverse stakeholders.     

Comparison of VOC and ammonia emissions from individual PVC materials, adhesives and from complete structures

Emission rates of volatile organic compounds (VOCs) and ammonia measured from six PVC materials and four adhesives in the laboratory were compared to the emission rates measured on site from complete structures. Significantly higher specific emission rates (SERs) were generally measured from the complete structures than from individual materials. There were large differences between different PVC materials in their permeability for VOCs originating from the underlying structure. Glycol ethers and esters from adhesives used in the installation contributed to the emissions from the PVC covered structure. Emissions of 2-ethylhexanol and TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) were common. High ammonia SERs were measured from single adhesives but their contribution to the emissions from the complete structure did not appear as obvious as for VOCs. The results indicate that three factors affected the VOC emissions from the PVC flooring on a structure: 1) the permeability of the PVC product for VOCs, 2) the VOC emission from the adhesive used, and 3) the VOC emission from the backside of the PVC product.